medical journal

 

Characterization of Methicillin-Resistant Staphylococcus Methicillin-Resistant  Staphylococcus aureus Strains aureus  Strains Recovered from a Phase IV Clinical Trial for Linezolid versus Vancomycin for Treatment of Nosocomial Pneumonia Rodrigo E. Mendes,a Lalitagauri M. Deshpande,a Davida S. Smyth,b Bo Shopsin,b David J. Farrell,a and Ronald N. Jonesa,c a

b

JMI Laboratories, North Liberty, Iowa, USA ; Department of Medicine, NYU School of Medicine, New York, New York, USA ; and Tufts University School of Medicine, Boston, Massachusetts, USAc

A total of 434 methicillin-resistant Staphylococcus methicillin-resistant Staphylococcus aureus (MRSA) aureus (MRSA) baseline isolates were collected from subjects enrolled in a prospective, double-blind randomized trial comparing linezolid versus vancomycin for the treatment of nosocomial pneumonia. Isolates were susceptibility tested by broth microdilution, examined for inducible clindamycin resistance by D-test, and screened for heterogeneous resistance to vancomycin (hVISA) by the Etest macromethod. All strains were subjected to PantonValentine leukocidin (PVL) screening, and SCCmec  SCCmec , pulsed-field gel electrophoresis (PFGE), and spa and spa typing.  typing. Selected strains  were evaluated by multilocus sequence typing (MLST). Clonal complexes (CCs) were assigned based on the spa the spa and/or  and/or MLST results. Most strains were CC5 (56.0%), which originated origin ated from North America (United States) (CC5-MRSA-SCCmec  (CC5-MRSA-SCCmec  II/IV;   II/IV; 70.0%), Asia (CC5-MRSA-II; 14.0%) and Latin America (CC5-MRSA-I/II; 12.3%). The second- and third-most-prevalent clones  were CC8-MRSA-IV (23.3%) and CC239-MRSA-III (11.3%), respectively. Furthermore, the CC5-MRSA-I/II CC5-MRSA-I/II clone predominated in Asia (50.7% within this region) and Latin America (66.7%), followed by CC239-MRSA-III (32.8% and 28.9%, respectively). The European strains were CC8-MRSA-IV (34.5%), CC22-MRSA-IV (18.2%), or CC5-MRSA-I/II/IV (16.4%), while the U.S. MRSA isolates were CC5-MRSA-II/IV (64.4%) or CC8-MRSA-IV (28.8%). Among the U.S. CC8-MRSA-II/IV strains, 73.7% (56/76 [21.2% of all U.S. MRSA strains]) clustered within USA300. One strain from the United States (USA800) was intermediate to vancomycin (MIC, 4 g/ml). All remaining strains were susceptible to linezolid, daptomycin, vancomycin, and teicoplanin. hVISA strains (14.5%) were predominantly CC5-MRSA-II, from South Korea, and belonged to a single PFGE type. Overall, each region had two predominant clones. The USA300 rate corroborates previous reports describing increased prevalence of USA300 strains causing invasive infections. The prevalence of hVISA was elevated in Asia, and these strains were associated with CC5.

Srial infections worldwide, and the incidence of health care-

taphylococcus aureus remains aureus remains a leading cause of human bacte-

associated and comm associated community unity-acq -acquired uired (CA) infec infections tions caused by  this organism has increased steadily (7 (7). This species ranks as the main pathogen responsible for nosocomial bloodstream infections (BSI), hospital-acquired bacterial pneumonia (HABP) and ventilator-acquired bacterial pneumonia (VABP), and skin and skin structure infections (SSSI) (20 ( 20,,   25 25)). Many infections are caused by methicillin-resista methicillin-resistant nt S.  S. aureus (MRSA) aureus (MRSA) isolates, and recent studies have demonstrated an increased MRSA incidence over the last decade (31 (31,, 34  34,, 43  43,, 51  51)). These facts, along with complicat pli cating ing ris risk k fac factor tors, s, com comorb orbidi idity, ty, and mor mortal tality(betw ity(between een 40 and 60%), result in extended hospitalizations, escalated health care costs, and the requirement of potent, broad-spectrum agents often used in combination regimens (7 (7). The population structure of MRSA strains is constantly evolving. These epidemiologic alterations reflect in changes in the incidence and characteristics of MRSA infections in the hospital and communit comm unityy setti settings. ngs. In the United States, the USA30 USA300 0 clone emerged as important cause of CA-MRSA infections, predominantly SSSI (29 (29)). Recently, this clone has also been implicated as a cause of health care-associated (HA-MRSA) and invasive infections (22 (22,, 39  39,, 45  45). ). However, recent studies have demonstrated an overall increase of noninvasive, community-onset, MRSA infections,, whil tions whilee the incidence of HA-MR HA-MRSA SA and invasive infections infections declined (8 (8, 21  21,, 31  31,, 51  51)). Similar changes in the MRSA epidemiology among European hospitals have been reported in numerous studies as well (6 (6,  9  9,,  14  14,,  16  16)). Moreover, CA-MRSA has recently 

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emerged across Europe (2 (2,  19  19,,  24  24,,  26  26)), and the incidence of HAMRSA MRS A BSIhas dec decrea reasedor sedor rem remain ained ed sta stablein blein sev severa erall cou countr ntriesin iesin Europe (24 (24)). From Fro m Oct Octobe oberr 200 2004 4 thr throug ough h Jan Januar uaryy 201 2010, 0, a pha phase se IV ran random dom-ized, double-blind, actively controlled study was performed to assess the efficacy and safety of linezolid compared with doseoptimizedvancomyc opti mizedvancomycin in for the treat treatment ment of cultu culture-pr re-proven oven MRSA nosocomial pneumonia (NP) in hospitalized adults (53 (53)). In this study,, a signi study significantl ficantlyy bette betterr clini clinical cal cure rate was obser observed ved with linezolid (58%) than with vancomycin (47%). Favorable results weree als wer also o obt obtain ained ed for lin linezo ezolid(58%) lid(58%) in ter terms ms of mic microb robiol iologi ogical cal cure rates compared with vancomycin (47%). During this trial, a large collection of geographically diverse MRSA isolates was obtained. This study sought to further characterize this worldwide MRSA population and evaluate possible changing trends of genotypes, molecular characteristics, and antimicrobial susceptibility  profiles of strains responsible for NP between 2004 and 2010.

Received 31 July 2012  Returned for modification  28 August 2012 Accepted 4 September 2012 Published ahead of print 12 September 2012

Address correspondence to Rodrigo E. Mendes, [email protected]. Supplemental material for this article may be found at http://jcm.asm.org/  at  http://jcm.asm.org/ . Copyright © 2012, American Society for Microbiology. All Rights Reserved. doi:10.1128/JCM.02024-12

p. 3694 –3 –3702

November 2012 Volume 50 Number 11

 

MRSA Strains from a Linezolid Pneumonia Trial

MATERIALS AND METHODS

Bacterial strains.   A total of 434 microbiologically evaluable baseline MRSA isolates were collected (from October 2004 through January 2010) from hospitalized subjects with clinically documented NP proven to be caused by MRSA. Subjects were required to have a baseline tracheal aspirate, bronchoalveolar lavage (BAL) fluid, or high-quality sputum specimen (defined as having less than 10 squamous epithelial cells and greater or equal to 25 leukocytes per high-power field) positive for MRSA (53 ( 53)). Baseline isolates included in this study originated from patients enrolled in the clinical trial according to preestablished inclusion criteria. Therefore, MRSA isolates included included in this study were not conse consecuti cutively vely collected and did not follow a prevalence mode design (53 (53)). Specimens were processed and cultured for bacterial pathogens according to the standard procedure at each medical center laboratory site. Individual investigators forwarded MRSA isolates to the Covance Central Laboratory Service (Indianapolis, IN) for confirmation of identification and susceptibility testing. MRSA isolates were subsequently sent to JMI Laboratories (North Libert Lib erty,IA) y,IA) forfurt forfurtherstudi herstudies.Onlyone es.Onlyone stra strainper inper pat patien ientt wasincl wasinclude uded d in this analysis. The strains included in this study were predominantly collected from enrolled subjects in the United States (264 [60.8%]), followed by smaller numbers numb ers of subje subjects cts from the following following coun countries: tries: South Korea (44 [10.1%]), Brazil (18 [4.1%]), Belgium (18 [4.1%]) Taiwan (15 [3.5%]), Russia (13 [3.0%]), Mexico (10 [2.3%]), Portugal (8 [1.8%]), Chile (8 [1.8%]), France (8 [1.8%]), Malaysia (6 [1.4%]), Puerto Rico (5 [1.2%]), South Africa (3 [0.7%]), Colombia (3 [0.7%]), Spain (2 [0.5%]), and Germany (2 [0.5%]), with 1 (0.2%) strain each from Singapore, Greece, Poland, the United Kingdom, Argentina, Hong Kong, and Turkey. Epidemiologic typing. Panton-Valentine typing. Panton-Valentine leukocidin (PVL) (lukF-PV  (lukF-PV  and lukS-PV  and  lukS-PV ) screening was performed by using a multiplex real-time PCR (RT-PCR) approach as previously described (30 ( 30)). SCCmec  SCCmec  types   types (I through VI) were characterized using a multiplex PCR strategy (32 (32)). Strains showing inconclusive SCCmec  SCCmec  typing   typing results were subjected to a secondary strategy proposed by Oliveira et al. (35 ( 35)). Typing of the  ag  agr  r  operon (groups I through IV) was assessed using multiplex RT-PCR as previously described by Strommenger et al. (49 (49). ). Bacter Bac terialchrom ialchromoso osomalDNA malDNA was dig digest ested ed wit with h Sma SmaII andsubje andsubjecte cted d to pulsed-field gel electrophoresis (PFGE). PFGE types were assigned according to the origin of the isolates (United States, Europe [including Russiaa and Turke Russi Turkey], y], Latin Amer America,the ica,the Asia Asian-Pac n-Pacific ific [APA [APAC] C] regio region, n, and South Africa), followed by a capital letter (PFGE type) and a number (PFGE (PFG E subty subtype). pe).Gel Gel patt pattern ern anal analysis ysiswas was perf performe ormed d usin usingg the GelC GelCompa omparr II software (Applied Math, Kortrijk, Belgium), and the patterns obtained were compared those of the major U.S. andialinternational which were provid pro vided ed bytothe Netwo Ne twork rk on Antim Ant imic icrob robia l Res Resist istan ance ce inclones, S. aureus (NARSA; www.narsa.net)). Percent similarities were identified on a dendrogram dewww.narsa.net rived by the unweighted-pair group method using arithmetic averages and based base d on Dic Dicee coef coefficie ficients.Band nts.Band posi positiontoleran tiontolerance ce andoptimiz andoptimizatio ation n wereset at 1.3 and 0.5% 0.5%,, respe respectiv ctively ely.. Isola Isolates tes show showing ing sim similar ilarity ity coef coeffici ficient ent at 80% were considered genetically related (same PFGE type), while those with a similari simi larity ty coef coeffici ficient ent at 95%were ass assig igned ned the sam samee PF PFGE GE sub subty type pe (29 29)). All strains were subjected to spa to spa typing  typing (46 (46)). Clonal complexes (CCs) were assigned based on the  spa  typing results using the multilocus sequence typing (MLST) mapping database (http://spa.ridom.de/mlst (http://spa.ridom.de/mlst)) or peer-reviewed reports. Strains with new  spa  spa  typing denominations and previously previ ously unknown MLST assoc associatio iations, ns, but clus clusterin teringg withi within n PFGE types containing strains with similar patterns of  spa repeat  spa repeat sequences and known CC resul results, ts, were assign assigned ed the same CCs. MLST was performed performed (36 36)) for a given strain showing a spa a  spa type  type with an unknown MLST association and a unique PFGE pattern. See the supplemental material for additional related to the strains and molecular testing results (including information heterogeneous vancomycin-intermediate vancomycin-intermediate S.  S. aureus [hVISA], aureus  [hVISA], SCCmec  SCC mec , PVL, agr  PVL,  agr ,  spa  spa [Ridom  [Ridom and Kreiswirth nomenclatures]), MLST, and CCs generated during this study.

Novemb Nov ember er 2012 2012 Vol Volume ume 50 Num Number ber 11 11

Antimicrobial susceptibility profile. Isolates profile. Isolates were tested for susceptibility by broth microdilution in cation-adjusted Mueller-Hinton mediumaccordingg to the Clin diumaccordin Clinical ical and Labor Laboratory atory Stand Standards ards Instit Institute ute (CLSI) recommendationss (12 recommendation 12)). Quality assurance was performed by concurrent testing of CLSI-recommended (M100-S22) strains: Enterococcus strains:  Enterococcus faecalis ATCC 29212 and S. and  S. aureus ATCC aureus  ATCC 29213. Interpretation of MIC results was in accordance with published CLSI criteria (13 (13)). Inducible clindamycin resistance was detected using the D-test disk  diffusionmethod diff usionmethod acco accordingto rdingto CLSI (13 13)). Br Brie iefly fly,, a 2-g clin clindamy damycin cin disk  wass pl wa plac aced15 ed15 mmfro mmfrom m theedg theedgee ofa 15 15--g eryth erythromy romycin cin disk. Foll Following owing incubatio incuba tion, n, iso isolat lates es tha thatt sho showedflatte wedflattenin ningg of theclind theclindamy amycinzone cinzone on the edge adjacent to the erythromycin disk were considered D-test positive. Screening for heterogeneous vancomycin-interm vancomycin-intermediate ediate S. aureu aureuss (hVISA) was performed using the Etest (bioMérieux, ( bioMérieux, Marcy l’Etoile, France) macromethod as previously described (30 (30)). RESULTS

Epidemiologic typing. MRSA typing.  MRSA strains will be referred to herein according to the CC and SCCmecA SCCmecA  typing results. Therefore, CC5-MR CC5 -MRSASA-II II ind indica icates tes tha thatt a par partic ticula ularr str strain ain or gro group up of str strain ainss are associated with CC5 and carried SCCmec  SCC mec  type   type II. The most frequent clone identified in this study was CC5-MRSA-I/II/IV (56.0% [243/434]), [243/434]), follo followed wed by CC8-M CC8-MRSA-I RSA-IV V (23.3% [101/ 434]) and CC239-MRSA-III (11.3% [49/434]), while another 10 CCs detected were each represented by  3.5% of the total strains included (Table (Table 1) 1). MRSA strains associated with CC5 (56.0%) originated mostly from the Unit originated United ed State Statess (CC5-M (CC5-MRSA-I RSA-II/IV I/IV;; 70.0% [170/243]), Asia (CC5-MRSA-II; 14.0% [34/243]), and Latin America (CC5-MRSA-I/II; 12.3% [30/243]). CC8 MRSA strain str ainss wer weree mos mostt com common monly ly obs observ erved ed in theUnite theUnited d Sta States(75.2% tes(75.2% [76/10 [76 /101]) 1]) andEurop andEuropee (18. (18.8% 8% [19 [19/10 /101]) 1]) (Tab Table le 1), whi while le thethird thethird-most-observ mostobserved ed MRSA MRSAlinea lineage ge (CC239(CC239-MRSAMRSA-III) III)was was more commonly noted in Asia (44.9% [22/49]) and Latin America (26.5% [13/49]), where these strains represented the second-most-common clone (Table (Table 1) 1). The majority (64.4% [170/264]) of clinical trial strains collected from the United States were CC5-MRSA-II/IV, agr  CC5-MRSA-II/IV,  agr  type   type 2 and PVL negative (Table (Table 2) 2). Among these strains, 159 and 11 carried SCCmec  SCCmec  types  types II and IV, respectively. While most CC5MRSA-II strains (69.2% [110/159]) clustered within a PFGE type (USA-B) with profiles similar to or indistinguishable from that of  the USA100 strain, the other CC5-MRSA-II isolates were distributed ute d amo among ng 14 clu cluste sters rs (PF (PFGE GE typ types) es).. All 11 CC5CC5-MRS MRSA-I A-IV V strains clustered within USA-N, which showed PFGE patterns similar to or indistinguishable from that of NRS387, a representativeof tat iveof USA USA800.The 800.The sec second ond maj major or clu cluste sterr det detect ected ed in the Uni United ted States Sta tes was CC8 CC8-MR -MRSASA-IV IV (28 (28.8% .8% [76 [76/26 /264]) 4]),, amo among ng whi which ch 73. 73.7% 7% (56/76 (56 /76 [21. [21.2% 2% of allU.S. str strain ains]) s]) (Tab Table le 2) wer weree PVL pos positi itive ve and cluste clu stered red wit within hin USA USA-A -A (US (USA30 A300 0 pat patter tern) n) (Tab Table le 2). CC CC88MRSA-I MRS A-IV, V, whi which ch was PVL neg negati ative, ve, fro from m the Uni United ted Sta States tes grouped into nine PFGE types (six  spa  spa  types), including isolates with PFGE patterns similar to USA500 (USA-Q) (Table ( Table 2) 2). Figure 1 displays 1 displays the percentages of CC8-MRSA-IV (USA300) compar com pared ed to CC5 CC5-MR -MRSASA-II II str strain ainss (agr  agr ty type pe 2, US USA1 A100 00 an and d as asso so-ciated ancestors) recovered during each year of the study period. Only one and three strai strains ns included in the study were coll collected ected during 2004 and 2010, respectively (data not shown). Thus, these 2-year periods were excluded from this analysis. A total of 64.0% (32/50)) of the USA100 strains (32/50 strains were recovered recovered from subje subjects cts included in 2005 versus 10.0% (5/50) of USA300 strains. However, 45.1% 45. 1% (23 (23/51 /51)) of USA USA100 100 str strain ainss wer weree obs observ erved ed in 2009agains 2009againstt an

 

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TABLE 1 Clonal 1 Clonal distribution of MRSA isolates (unique strains) recovered from subjects enrolled in a phase IV pneumonia clinical trial for linezolid No. (%) of strains Clonal complex 

United States

Europea

Latin Americab

Asiac 

Total

CC5 CC5-MRSA-I CC5-MRSA-II CC5-MRSA-IV

170 (64.4) 0 (0.0) 159 (60.2) 11 (4.2)

9 (16.4) 3 (5.5) 4 (7.3) 2 (3.6)

30 (66.7) 13 (28.9) 17 (37.8) 0 (0.0)

34 (50.7) 0 (0.0) 34 (50.7) 0 (0.0)

243 (56.0) 16 (3.7) 214 (49.3) 13 (3.0)

CC8-MRSA-IV

76 (28.8)

19 (34.5)

1 (2.2)

5 (7.5)

101 (23.3)

CC239-MRSA-III CC45-MRSA-II/III/IV CC22-MRSA-IV CC30-MRSA-II CC59-MRSA-IV CC398-MRSA-III/IV CC1-MRSA-IV CC9-MRSA-II CC72-MRSA-IV CC80-MRSA-IV CC96-MRSA-III CC97-MRSA-IV

4 (1.5)e  7 (2.7) 0 (0.0) 4 (1.5) 1 (0.4) 0 (0.0) 1 (0.4) 0 (0.0) 1 (0.4) 0 (0.0) 0 (0.0) 0 (0.0)

7 (12.7) f   6 (10.9) 10 (18.2) 1 (1.8) 0 (0.0) 1 (1.8) f   0 (0.0) 0 (0.0) 0 (0.0) 1 (1.8) 1 (1.8) 0 (0.0)

13 (28.9) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.2)

22 (32. g 8) 1 (1.5) 0 (0.0) 0 (0.0) 3 (4.5) 1 (1.5) g  0 (0.0) 1 (1.5) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)

49 (11.3)d  14 (3.2) 10 (2.3) 5 (1.2) 4 (0.9) 2 (0.5) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2)

Total

264 (60.8)

55 (12.7)

45 (10.4)

67 (15.4)

434 (100.0)

a

Includes isolates from Belgium, France, Germany, Greece, Poland, Portugal, Russia, Spain, Turkey, and the United Kingdom. Includes isolates from Argentina, Brazil, Chile, Colombia, Mexico, and Puerto Rico. c  Includes isolates from Hong Kong, South Korea, Malaysia, Singapore, and Taiwan. d  Includes three CC239-MRSA-III strains from South Africa. e  MRSA strains carrying SCCmec  SCCmec  type  type II.  f   MRSA strain carrying a SCCmec  SCCmec  type  type IV.  g  MRSA strains carrying SCCmec  SCCmec  type  type III. b

increasing 33.3% (17/51) of USA300 MRSA isolates (P  ( P   0.0049; odds ratio [OR]  0.21 [range, 0.06 to 0.73]). A greate greaterr genet genetic ic diversity diversity was observed among strains from European countries, including Russia and Turkey. Isolates were mostly mos tly CC8CC8-MRS MRSA-I A-IV V (34 (34.5% .5% [19/ [19/55]) 55]) or CC2 CC22-M 2-MRSA RSA-IV -IV (18.2%[10/55 (18 .2%[10/55]) ]) (Tab Tables1 les1 and 2). CC8-M CC8-MRSA-I RSA-IV V strai strains ns clust clustered ered within three PFGE types (EUR-D, -E, and -F), among which EUR-D (from Belgium, France, and Russia) and -E (all from Belgium) were also similar to the EMRSA-6 and USA500 patterns, respectiv respe ctively ely (Ta Tabl blee 2). All CC22 CC22-MR -MRSASA-IV IV str strain ainss clu cluste stered red within EUR-B, also known as EMRSA-15, and originated from Portug Por tugal al (70. (70.0% 0% [7/ [7/10]) 10]),, Bel Belgiu gium m (10. (10.0% 0% [1/ [1/10]) 10]),, Ger German many  y  (10.0% [1/10]), and the United Kingdom (10.0% [1/10]). MRSA isolat iso lates es fro from m Eur Europeassoc opeassociat iated ed wit with h CC5 pos posses sessedSCC sedSCCmec  mec types types I, II, or IV. CC5CC5-MRS MRSA-I A-I iso isolat lates es gro groupe uped d wit within hin EUR EUR-I -I and ori origginated from Poland and Spain (Table ( Table 2) 2). Four CC5-MRSA-II strain str ainss fro from m Bel Belgiu gium m sho showed wed a uni uniquePFGE quePFGE pat patter tern n (EU (EUR-G R-G;; spa type 437), which matched that of NRS382 (USA100), while one CC5-MRSA-IV strain each from Belgium (EUR-H;   spa spa type  type 2) and Franc Francee (EUR(EUR-M; M; spa typ typee 1480 1480)) was det detect ected ed (Tab Table le 2). Oth Other er less prevalent lineages noted in Europe are as follows: CC398MRSA-IV MRSAIV (one strai strain n from Belgium), Belgium), CC239-M CC239-MRSA-I RSA-III II (one strain each from France and Turkey and four isolates from Russia), CC80-MRSA-IV (one strain from Greece), CC96-MRSA-III (one strain from Russia), CC45-MRSA-IV (five strains from Belgium and one from Germany), and CC30-MRSA-II (one strain from Portugal) (Table (Table 1). 1). The most prevalent clone found in Latin America was CC5MRSA-I MRS A-I/II /II (66 (66.7% .7% [30/ [30/45]) 45]),, fol follow lowed ed by CC23 CC239-M 9-MRSA RSA-II -IIII (28.9% [13/45]) (Table (Table 1) 1). CC5-MR CC5-MRSA-I SA-I isolates were repre repre--

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sented by the LAT-C (84.6% [11/13]), LAT-D (7.7% [1/13]), and LAT-E (7.7% [1/13]) PFGE types, among which LAT-C showed profiles that matched that from a representative of the Cordobes/ Chilean clone (Tables (Tables 1 and 1  and  2  2)). LAT-C strains originated from Chile Chi le (72 (72.7% .7% [8/ [8/11] 11])) and Col Colomb ombia ia (27. (27.3% 3% [3/ [3/11]) 11]).. Tho Those se str strain ainss associated assoc iated with CC5-MR CC5-MRSA-II SA-II clus clustered tered withi within n LAT-A (47.0% (47.0%[8/ [8/ 17]), LAT-B (35.3% [6/17]), LAT-L (5.9% [1/17]), and LAT-N (11.8% [2/17]). All LAT-A strains were collected from Mexico, while whi le LAT LAT-B -B MRS MRSA A iso isolat lates es wer weree fro from m Pue Puerto rto Ric Rico o (50 (50.0% .0% [3/ [3/6]) 6]),, Brazil(33.3% Bra zil(33.3% [2/ [2/6]) 6]),, or Mex Mexico ico (16. (16.7% 7% [1/ [1/6]) 6]).. All CC23 CC239-M 9-MRSA RSA-III strains (28.9% [13/45]) observed from Latin America originated from a single country (Brazil). Other minor clones were CC97-MRSA-IV (2.2% [1/45]) and CC8-MRSA-IV (2.2% [1/ 45]). The latter strain originated from Puerto Rico and demonstrated molecular and PFGE profiles (LAT-F) similar to those of  the USA300 clone (Table (Table 2) 2). Overall, strains from the APAC region were CC5-MRSA-II (50.7% [34/67]) or CC239-MRSA-III (32.8% [22/67]), PVL negative, ativ e, and agr  agr ty type pess 2 an and d 1, re resp spec ecti tive vely ly (Tab Tables les 1 and 2). Fi Fiveand veand three isolates were CC8-M CC8-MRSA-I RSA-IV V and CC59-M CC59-MRSA-I RSA-IV, V, which were from South Korea (ASI-D) and Taiwan (ASI-K and -L), respectively (Table (Table 3) 3). One strain from Taiwan was CC398-MRSAIII, agr  III,  agr  type  type 1, and PVL negative, while a single strain collected from Hong Kong was CC45-MRSA-III, agr  CC45-MRSA-III, agr  type  type 1, and PVL negative (Table (Table 2) 2). Regarding PFGE patterns, the majority of APAC MRSA MRS A str strain ainss clu cluste stered red wit within hin ASI ASI-A -A (26 (26/67 /67 [38. [38.8%] 8%])) or -I (15 (15/67 /67 [22.4% [22 .4%]). ]). Iso Isolat lates es sho showin wingg the ASI ASI-A -A PFG PFGE E typ typee wer weree CC5MRSA-II, spa ty type pe 2 or re rela late ted d ty type pes, s, an and d agr  agr ty type pe 2, al also so kn know own n as the New Yor York/J k/Japa apan n clo clone, ne, whe wherea reass tho those se bel belongi onging ng to ASI ASI-I -I wer weree CC239-MRSA-III, spa ty type3, pe3, an and d agr  agr type type 1 (Hunga (Hungarian/ rian/Brazi Brazilian lian

Journal of Clinical Microbiology

 

MRSA Strains from a Linezolid Pneumonia Trial

TABLE 2 Epidemiologic 2 Epidemiologic data of baseline MRSA isolates (unique strains) recovered during a phase IV pneumonia clinical trial for linezolid No. (%)

SCCmec  type

PVLa

1 (100.0) 22 (50.0) 3 (6.8) 2 (4.5) 5 (11.4) 1 (2.3)

III II II II IV II

           

     

1 8 ((2 1.83.)2) 1 (2.3) 1 (2.3) 1 (16.7) 5 (83.3) 1 (100.0) 4 (26.7) 4 (26.7) 1 (6.7) 1 (6.7) 2 (13.3) 1 (6.7) 1 (13.3) 1 (13.3)

IIIIII II II II III III II III III III IV IV III III

                             

5 (27.8)

IV

1 (5.5) 1 (5.5) 5 (27.8) 4 (22.2) 1 (5.5) 1 (5.5) 6 (75.0) 1 (12.5) 1 (12.5) 1 (50.0) 1 (50.0) 1 (100.0) 1 (100.0) 7 (87.5) 1 (12.5) 3 (23.1) 4 (30.8)

IV IV IV II IV IV IV III IV IV IV IV I IV II IV IV

5 (38.5) 1 (7.7) 2 (100.0) 1 (100.0) 1 (100.0)

III III I III IV

South Africa (3)

3 (100.0)

Nort No rth h Am Amer eric icaa (U (Uni nite ted d St Stat ates es;; 26 264) 4)

56 (2 (21. 1.2) 2) 110 (41.7) 17 (6.4) 1 (0.4) 5 (1.9) 10 (3.8) 4 (1.5) 1 (0.4) 2 (0.8) 1 (0.4) 1 (0.4)

Region or country (no. tested) APAC (67) Hong Kong (1) South Korea (44)

Malaysia (6) Singapore (1) Taiwan (15)

Europe (55) Belgium (18)

France (8)

Germany (2) Greece (1) Poland (1) Portugal (8) Russia (13)

Spain (2) Turkey (1) United Kingdom (1)

agr  type

PFGE

           

1 2 2 2 1 2

              

                            

 



                       

spa  type(s) spa

CC no.

ASI-J ASI-Ab ASI-B ASI-C ASI-D ASI-E

433 232, 23 2, 10 1095 95,, 14 1478 78,, 14 1479 79 2 2, 1095 451, 554 2

45 5 5 5 8 5

1 1 2 2 1 1 1 2 1 1 1 1 1 1 1

A ASSII--G I ASI-M ASI-N ASI-F ASI-I ASI-I ASI-A ASI-G ASI-H ASI-I ASI-K ASI-L NTc  NT

3 3 2 1095 1152 3 3 2, 14 3 3 3 143, 778 776 539 3

2 23 39 9 5 5 8 239 239 5 239 239 239 59 59 398 239

 

1

EUR-Ad 

756, 1484

45

                

                                 

1 1 1 2 2 1 1 1 2 1 1 3 2 1 3 1 1

EUR-Be  EUR-D f   EUR-E g  EUR-Gb EUR-H NT EUR-D EUR-K EUR-M EUR-B EUR-L EUR-J EUR-I EUR-B EUR-C EUR-D EUR-F

382 1 1, 4, 366 437 2 1485 1 351 35 1480 382 15 70 70 388 38 382, 816, 1473 16 1 1

22 8 8 5 5 398 8 239 5 22 45 80 5 22 30 8 8

   

    

         

1 3 2 1 1

EUR-K EUR-N EUR-I EUR-K EUR-B

351 35 999 1481, 1488 351 35 382

239 96 5 239 22

III

 



 

1

SA-A

3

239

IV II II II II II II IV II IV IV

                   

         

 



                     

1 2 2 2 2 2 2 1 2 1 1

USA-Ah USA-Bb USA-C USA-D USA-E USA-F USA-G USA-H USA-I USA-J USA-K

1, 59 59,, 245 45,, 36 363, 3, 14 1487 87 See footnote i footnote i   2, 11, 24, 50, 230 2 2, 24, 29, 302 2, 24, 58 2, 11, 302 1 2, 1475 1 363

8 5 5 5 5 5 5 8 5 8 8

               

 

(Continued on following page)

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TABLE 2 (Continued) 2 (Continued) Region or country (no. tested)

Latin America (45) Argentina (1) Brazil (18)

Chile (8) Colombia (3) Mexico (10)

Puerto Rico (5)

a

No. (%)

SCCmec  type

PVLa

3 (1.1) 1 (0.4) 11 (4.2) 1 (0.4) 1 (0.4) 10 (3.8) 1 (0.4)

II II IV II IV IV IV

             

      

4 1 ((1 0..5 4)) 1 (0.4) 2 (0.8) 1 (0.4) 7 (2.7) 4 (1.5) 1 (0.4) 1 (0.4) 1 (0.4) 1 (0.4) 1 (0.4) 1 (0.4) 2 (0.8)

IIIVI II IV II II II IV II II II IV IV IV

                           

1 (100.0) 2 (11.0)

I II

   

1 (5.5) 5 (27.8) 3 (16.7) 2 (11.1) 2 (11.1) 1 (5.5) 1 (5.5) 1 (5.5) 8 (100.0) 3 (100.0) 8 (80.0) 1 (10.0) 1 (10.0) 3 (60.0) 1 (20.0) 1 (20.0)

I III III III III III IV II I I II II II II IV II

                               

agr  type

PFGE

             

2 2 2 2 3 1 1

             

                          

                 

 

spa  type(s) spa

CC no.

USA-L USA-M USA-N j  USA-O USA-P USA-Q g  USA-R

2 303 2, 23 23,, 24 24,, 29 29,, 20 203, 3, 69 693 3 24 175 1, 7 139

5 5 5 5 1 8 8

1 1 2 1 2 1 / NT 1/ 3 1 2 2 2 1 1 1

U USSA A--ST USA-U USA-V USA-W USA-Xd   USA-Yk USA-Z USA-AA USA-AB USA-AC USA-AEl  USA-AFm USA-AG

3 1 12 1 1070 10, 15, 62, 1472 16, 33 1 337 11 11 206 1482 68, 1486

2 839 5 8 5 45 30 8 5 5 5 59 72 8

   

2 2

LAT-D LAT-B

58 2

5 5

                               

2 1 1 1 1 1 1 2 2 2 2 2 2 2 1 2

LAT-E LAT-G LAT-H LAT-I LAT-J LAT-K LAT-M LAT-N LAT-Cn LAT-C LAT-A LAT-B LAT-N LAT-B LAT-Fh LAT-L

2 3 3 3 3 3 92 2 442 442 58, 1474 58 29 2 1 2

5 239 239 239 239 239 97 5 5 5 5 5 5 5 8 5

PVL, Panton-Valentine leukocidin. , present; , absent.

b

PFGE type indistinguishable from or similar to that of USA100. NT, nontypeable. d  PFGE type indistinguishable from or similar to that of USA600. e  PFGE type indistinguishable from or similar to that of EMRSA-15.  f   PFGE type indistinguishable from or similar to that of EMRSA-6.  g  PFGE type indistinguishable from or similar to that of USA500. h PFGE type indistinguishable from or similar to that of USA300. i Strains represented by  spa types  spa  types 2, 23, 24, 25, 29, 47, 50, 58, 65, 203, 230, 268, 300, 336, 442, 487, 841, 1206, 1476, 1477, and 1483.  j  PFGE type indistinguishable from or similar to that of USA800. k PFGE type indistinguishable from or similar to that of USA200. l  PFGE type indistinguishable from or similar to that of USA1000. m PFGE type indistinguishable from or similar to that of USA700. n PFGE type indistinguishable from or similar to that of Cordobes/Chilean. c 

clone) ((Table Table 2) 2). Among ASI-A strains, the vast majority (22/26 [84.6% [84 .6%]) ]) ori origin ginate ated d fro from m fou fourr hos hospit pitals als in Sou South th Kor Korea, ea, whi while le the remaining four strains were from two hospitals in Taiwan (4/26 [15.4%]). In contrast, strains clustering within ASI-I (10 subtypes) were from South Korea (8/15 [53.3%]), Malaysia (5/15 [33.3%]), Singapore (1/15 [6.7%]), and Taiwan (1/15 [6.7%]) (Table 2) 2).

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Antimicrobial susceptibility profiles. Table profiles. Table 3 displays 3 displays the activities and susceptibility profiles of selected agents tested against MRSA strains according to lineage. Overall, linezolid (MIC50, 2 g/ml), vancomycin (MIC50, 1 g/ml), teicoplanin (MIC50, 0.5 g/ml), ), and dapto daptomyci mycin n (MIC50,0.5 g/m g/ml) l) sho showedstabl wedstablee MIC50 g/ml results when evaluated against each major CC. Exceptions were observed when teicoplanin was tested against the CC239 and

Journal of Clinical Microbiology

 

MRSA Strains from a Linezolid Pneumonia Trial

FIG1   Propo Proportionof rtionof uniqueCC8-MRSA uniqueCC8-MRSA-IV -IV (PVL(PVL-positi positive; ve; USA300 USA300)) and CC5-M CC5-MRSA-I RSA-III strai strains ns recov recovered ered fromsubjects enrol enrolled led in the UnitedStates durin duringg the study period. CC8-MRSA-IV strains were agr  were  agr  type  type 1 and PVL positive and clustered within the PFGE USA-A group (USA300). CC5-MRSA-II strains were agr  were  agr  type 2 and PVL negative.

CC22 2 str strain ains, s, whi which ch sho showed wed MIC50 val values ues 2-f 2-foldhigher(MIC oldhigher(MIC50, 1 CC2 g/ml) and 2-fold lower (MIC50, 0.25 g/ml) than those of the otherCC isola isolates, tes, respe respectiv ctively. ely. In addit addition, ion, CC22 strai strains ns exhib exhibited ited daptomycin MIC values (MIC 50/90, 0.25/0.5 g/ml) 2-fold lower than tha n tho those se of oth other er tes testedCC tedCC str strain ainss (MI (MIC C50/90, 0.5 0.5/1 /1 g/ml g/ml). ). One

MRSA strain from the United States exhibited a nonsusceptible phenot phe notypeto ypeto van vancom comyci ycin n (MI (MIC, C, 4 g/ml g/ml;; inter intermedia mediate) te) and clustered within USA-N (USA800). Tetracycline (MIC50, 0.25 g/ml [92. 92.9% 9% sus suscep ceptib tible] le])) was act activewhen ivewhen tes tested ted aga agains instt CC8,CC45, and CC22 strains, while 98.0% of CC239 MRSA isolates were

TABLE 3 Antimicrobial 3 Antimicrobial activity and susceptibility results of selected drugs tested against baseline MRSA clinical isolates (unique strains) by clonal complex recovered during a phase IV pneumonia clinical trial for linezolid MIC50/MIC90, g/ml (% susceptible) by a: CC

USA clone

Antimicrobial agent

CC5 (n (n  243)

CC8 (n  101)

CC239 (n  49 49))

CC45 CC 45 (n  14)

CC22 (n  10)

USA300 (n  56)

USA100 (n  110)

Linezolid Vancomycin Teicoplanin Daptomycin Erythromycin Clindamycin Gatifloxacin Tetracycline Q/Di TMP/SMX  j 

2/4 (100.0) 1/1 (99.6) 0.5/2 (100.0) 0.5/1 (100.0) 64/64 (1 (1.2 .2)) 64/64 (4.5)b 8/16 (4.9) 0.5/64 (87.3) 0.5/ 0. 5/1 1 (9 (99. 9.6) 6) 0.12 0. 12/0 /0.2 .25 5 (9 (98. 8.0) 0)

2/2 (100.0) 1/1 (100.0) 0.5/1 (100.0) 0.5/1 (100.0) 64/64 (8.9)   0.25/64 (61.4)c  2/16 (28.7) 0.25/1 (93.1) 0.25 0. 25/0 /0.5 .5 (9 (99. 9.0) 0) 0.06 0. 06/0 /0.5 .5 (9 (90. 0.1) 1)

2/2 (100.0) 1/1 (100.0) 1/2 (100.0) 0.5/1 (100.0) 64/64 (0 (0.0 .0)) 64/64 (0.0)d  4/16 (0.0) 32/64 (2 (2.0 .0)) 0.5/ 0. 5/0. 0.5 5 (1 (100 00.0 .0)) 16//32 (18 16 (18.4) .4)

2/4 (100.0) 1/2 (100.0) 0.5/2 (100.0) 0.5/1 (100.0) 0.5/ 0. 5/64 (57.1)   0.12/64 (57.1)e  4/8 (7.1) 0.25 0. 25/1 /1 (9 (92. 2.9) 9) 0.25 0. 25/0 /0.5 .5 (1 (100 00.0 .0)) 0.12/0 0.1 2/0.5 .5 (92 (92.9) .9)

2/2 (100.0) 1/1 (100.0) 0.25/0.5 (100.0) 0.25/0.5 (100.0) 64/64 (4 (40. 0.0) 0) 0.12/64 (40.0) f   8/16 (0.0) 0.25 0. 25/0 /0.2 .25 5 (1 (100 00.0 .0)) 0.25 0. 25/0 /0.2 .25 5 (1 (100 00.0 .0)) 0.06/0 0.0 6/0.06 .06 (10 (100.0 0.0))

2/2 (100.0) 1/1 (100.0) 0.5/1 (100.0) 1/1 (100.0) 64//64 (1.8)   64 0.25/64 (85.7) g  2/8 (32.1) 0.25 0. 25/0 /0.5 .5 (9 (98. 8.2) 2) 0.5/ 0. 5/0. 0.5 5 (1 (100 00.0 .0)) 0.06/0 0.0 6/0.12 .12 (10 (100.0 0.0))

2/4 (100.0) 1/1 (100.0) 0.5/1 (100.0) 0.5/1 (100.0) 64/64 (0.0) 64/64 (0.0)h 8/16 (2.7) 0.5/ 0. 5/1 1 (9 (98. 8.2) 2) 0.5/ 0. 5/0. 0.5 5 (1 (100 00.0 .0)) 0.12/0 0.1 2/0.25 .25 (95 (95.5) .5)

   

a

MICs were interpreted according to the M100-S22 document ( document (13 13)). Nonsusceptible strains are represented by 73.0% and 22.5% of constitutive and inducible resistance phenotypes, respectively. c  Nonsusceptible strains are represented by 32.6% and 6.0% of constitutive and inducible resistance phenotypes, respectively. d  Nonsusceptible strains are represented by 81.6% and 18.4% of constitutive and inducible resistance phenotypes, respectively. e  Nonsusceptible strains are represented by 42.9% of constitutive resistance phenotypes.  f   Nonsusceptible strains are represented by 20.0% and 40.0% of constitutive and inducible resistance phenotypes, respectively. b

 g  Nonsusceptible strains are represented by 10.7% and 3.6% of constitutive and inducible resistance phenotypes, respectively. h

Nonsusceptible strains are represented by 66.4% and 33.6% of constitutive and inducible resistance phenotypes, respectively. Q/D, quinupristin-dalfo quinupristin-dalfopristin. pristin.  j  TMP/SMX, trimethoprim-sulfa trimethoprim-sulfamethoxazole. methoxazole. i

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tetra tetracycl cycline ine resis resistant. tant. Trim Trimethop ethoprim-s rim-sulfa ulfametho methoxazole xazole (TMP/ SMX) showed potent activity (MIC50/90, 0.06 to 0.12/0.06 to 0.5 g/ g/ml ml [90. 90.1% 1% sus suscep ceptib tible] le])) agai against nst all maj major or CC gro groups ups,, exc except ept for CC23 CC239 9 str strain ainss (MI (MIC C50/90, 16 16//32 g/ml [18.4% susce susceptibl ptible]). e]). USA300 strains were susceptible to most antimicrobial agents tested (98.2% susceptible), except for erythromycin (1.8% susceptible) and gatifloxacin (32.1% susceptible), which were inactive. Clindamycin demonstrated a potent MIC 50 result (0.25 g/ ml) when tested against MRSA belonging to the USA300 lineage.

MRSA-II (New York/Japan), ST5-MRSA-IV (pediatric), ST22MRSA-I MRS A-IV V (UK (UK-EM -EMRSA RSA-15 -15)) and ST8 ST8-MR -MRSASA-IV IV (US (USA300 A300,, USA500, and UK-EMRSA-2 and -6) (18 (18,, 33  33,, 36  36,, 41  41)). In the United States, ST5-MRSA-II (USA100) has been the most common nosocomial MRSA clone, which has been implicated for approximately 60 to 68% of hospital-onset or hospitalacquired infections (HA-MRSA) (10 (10,,  27  27)). The rate (60.2% [159/ 264]) of CC5-MRSA-II (USA100) strains observed in this study  corrob cor robora orates tes tho those se pre previo viousl uslyy rep report orted ed and con confirm firmed ed USA USA100 100 as

However, Howeve r, 10. 10.7 7 and 3.6 3.6% % of iso isolat lates es exh exhibi ibited ted,, res respec pectiv tively ely,, con consti sti-tutive and inducible resistance phenotypes for clindamycin, resulting sult ing in a subop suboptima timall overa overall ll susce susceptib ptibilit ilityy resul resultt (85.7% susce suscepptible)and tib le)and an ele elevat vated ed MIC90 res result( ult( 64 g/m g/ml). l). CC5 iso isolat lates es and their regional U.S. subset (USA100) showed a similar susceptibility profile, except for tetracycline. When tested against all CC5 strains, strai ns, tetra tetracycl cycline ine demon demonstrat strated ed MIC90 resul results ts (MIC50/90, 0.5 0.5/64 /64 g/ml) higher than those of the USA100 subset (MIC50/90, 0.5/1 g/ml), which translated into slightly different susceptibility profiles (87.3 versus 98.2%, respectively). Among tetracycline-resistant CC5 strains, 27 of 31 (87.1%) originated from four hospitals in South Korea, and 19 of 27 (70.4%) belonged to a unique PFGE type (ASI-A; data not shown). Other tetracycline-resistant CC5 isolates were from the United States (three strains) or Belgium (one strain). Overall, 14.5% (63/434) isolates were characterized as hVISA,

an important cause of HA-MRSA infections. However, studies reported that USA300 strains are now responsible for 15.7 to 20.0% of the invasive HA-MRSA infections in the United States (10 10,, 22 22,, 27 27)). An ove overal ralll USA USA300 300 pre preval valenc encee rat ratee (21. (21.2%) 2%) sim simila ilarr to those reported previously was observed in this study. In addition, the pro propor portio tion n of USA USA300 300 str strain ainss app appear earss to hav havee inc increa reased sed slightly throughout the study period (Fig. (Fig. 1) 1). Overall, rates of  USA300 were 10.0 to 22.4% during 2005 to 2008, while CC5MRSA-II represented 58.7 to 67.2% of strains included. In 2009, USA300 and CC5-MRSA-II strains comprised 33.3 and 45.1% of  all isolates, respectively. These results support previous data indicating that the proportion of infection cases caused by USA300 has increased and that it may be slowly replacing the traditional HA-MRS HAMRSA A str strain ainss (31 31,, 39 39)). Ho Howe weve ver,thispie r,thispieceof ceof da data ta ne need edss tobe analyzed carefully, since the inclusion of the isolates in this pneumonia trial did not follow prevalence mode design criteria. Grundmann et al. (19 (19))  recently reported the detection of genetic net ic div divers ersity ity amo among ng MRS MRSA A str strain ainss cau causin singg inv invasi asive ve inf infect ection ionss in Europe, with CC5 (30.3%) being the most prevalent lineage, followed low ed by CC22 (16.9%), (16.9%), CC8 (15. (15.3%) 3%),, and CC239 (5. (5.0%) 0%).. Change Cha ngess wit within hin the MRS MRSA A pop popula ulatio tion n hav havee bee been n wel welll doc docuumented in European countries, such as Germany (2 (2), Ireland and Spain (38 (38,,  47  47)), and Portugal (1 (1,  4  4)). Additional reports have described alterations in the MRSA epidemiology among other European countries (6 (6, 9  9,, 14  14,, 16  16)). The results reported here corroborate those reported by Grundmann et al. (19 ( 19), ), who showed a greate gre aterr gen geneti eticc div divers ersity ity and sim simila ilarr dis distri tribut bution ion of MRS MRSA A CCs.In addition, the results described here and elsewhere indicate that previousl prev iouslyy preva prevalent lent clone clones, s, such as ST247ST247-MRSAMRSA-II (Iber (Iberian; ian; CC8), ST228ST228-MRSAMRSA-II (Sout (Southern hern Germ Germany; any; CC5), ST239ST239-MRSAMRSAIII (CC239; Brazi Brazilian/ lian/Hungar Hungarian), ian), and ST45-M ST45-MRSA-I RSA-IV V (CC45;

according to the employed method. The countries with the highest hVISA rates (countries with   10 strains) were as follows: South Sou th Kor Korea ea (61 (61.4% .4% [27 [27/44 /44]), ]), Bra Brazil zil (40 (40.4% .4% [8/ [8/18] 18]), ), Rus Russia sia (23.1% [3/13]), Mexico (20.0% [2/10]), Taiwan (13.3% [2/15]), and the United States (5.3% [14/264]) (data not shown). The occurrences of hVISA strains were higher within CC30-MRSA-II strains (40.0% [2/5]), followed by CC239-MRSA-III (22.4%; [11/ 49]), CC45-M CC45-MRSA-I RSA-II/III I/III (21.4% [3/14] [3/14]), ), CC5-MR CC5-MRSA-I/ SA-I/II/IV II/IV (16.5% [40/243]), and CC8-MRSA-IV (6.9% [7/101]) strains. Among CC5 hVISA strains, the majority were collected from South Korea (65.0% [26/40]) and belon belonged ged mostly (76.9% [20/ 26]) to a unique PFGE type (ASI-A). Two CC30 hVISA isolates were recovered from the United States and Portugal (one each), while CC45 hVISA strains originated from three U.S. hospitals and clustered within USA600 (USA-X). hVISA strains associated with CC239-MRSA-III were collected from scattered countries, such as Brazil (six strains), Russia (three strains), Malaysia (one strain), and Turkey (one strain). Differences in the susceptibility  profiles between hVISA and non-hVISA strains were not observed.

Berlin, Germany), have decreased occurrences or have no longer been detected (15 (15). ). In contrast, Alp et al. (3 ( 3)  described the persistence of ST239MRSA-III among eight university hospitals in Turkey over a 10 year period. Previous reports have also described a significant dominance (80.0%) of ST239-MRSA-III within Russian hospiDISCUSSION (5,  52  52,,  54  54). ). Interestingly, this study detected a higher prevaThe majority (56.0%) of the microbiologically evaluable baseline tals (5 MRSA isolates responsible for NP and included in this study be- lence (53.8%) of CC8-MRSA-IV causing NP in Russia, while longed longe d to CC5-M CC5-MRSA-I RSA-I/II/ /II/IV. IV. Howev However, er, when whenanalyz analyzing ing the prev- ST239-MRSA-III represented 38.5% of strains from this region. alence ale nce of MRS MRSA A lin lineag eages es acc accord ording ing to the geo geogra graphi phicc reg region ions, s, two We are unaware of any previous report describing this clonal almajor clones predominated in each area. In the APAC and Latin teration in the HA-MRSA strain population in Russia, except for America regions, isolates associated with CC5-MRSA-I/II pre- an earlier publication reporting that 80.0% of the MRSA strains vailed, followed by CC239-MRSA-III. Isolates responsible for NP causing skin and skin-structure infections during a phase IV clin( 30), ), although a among U.S. hospitals were mostly associated with CC5-MRSA- ical trial in this country were CC8-MRSA-IV (30 II/IV and CC8-MRSA-IV, while in Europe, a greater clonal diver- higher CC8-MRSA-IV rate might be expected among strains resity was observed and CC8-MRSA-IV predominated, followed by  sponsible for skin infections. Still in Europe, one strain belonging (spa type  type 1485/ST398) was colsimilar occurrences of CC22-MRSA-IV and CC5-MRSA-I/II/IV. to a livestock-associated clone (spa lected from Belgium and one CC80-MRSA-IV strain (spa spa type  type 70; Overall, these lineages are comprised of the so-called pandemic clones, clone s, such as ST239ST239-MRSAMRSA-III III (Brazi (Brazilian/ lian/Hungar Hungarian), ian), ST5- PVL positive) was noted in Greece. The latter has been implicated

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as an important CA-MRSA clone in Europe, but it has also been responsible for documented HA-MRSA infections (26 ( 26)). CC5-MRSA-I,CC5-MRSA-I CC5-MR SA-I,CC5-MRSA-II, I, and CC239-M CC239-MRSA-I RSA-III II predo predomminatedamong ina tedamong Lat Latin in Ame Americ rican an cou countr ntriesand iesand rep repres resent ented ed 95. 95.6% 6% of  all strains. CC239-MRSA-III was the predominant clone found in this region, but recent investigations demonstrated that CC239MRSA-III has been partially replaced by the Cordobes/Chilean (CC5-M (CC 5-MRSA RSA-I) -I) and New Yor York/J k/Japa apan n (CC (CC5-M 5-MRSA RSA-II -II)) clo clones nes (30 30,, 42)). How 42 Howeve ever, r, CC23 CC239-M 9-MRSA RSA-II -IIII and CC5 CC5-MR -MRSASA-II wer weree det detect ected ed

United States. In addition, higher fluoroquinolone (67.9%) and clindamycin (14.3%) resistance rates (inducible and constitutive) were observed among USA300 strains. Moreover, a shift in the MRSA population was observed in Russia, with CC8-MRSA-IV replacing repl acing CC239-MRSA-III CC239-MRSA-III,, and a high prevalence prevalence of hVISA strains was observed in the APAC region, especially South Korea.

equally in the South America, while CC5-MRSA-II was most frequently observed in Mexico. Moreover, the latter has been the predominant clone in Mexico after 2002, when this lineage displaced ST30-MRSA-IV (30 (30)). More recently, the CC8-MRSA-IV (USA300) clone has also emerged in several South American countries (30 (30,,   40 40,,   42 42)). One USA300 strain (PVL-positive) collected from Puerto Rico was observed here. Among Amo ng tho those se MRS MRSA A str strain ainss ori origin ginati ating ng fro from m theAPAC reg region ion,, the CC5-MR CC5-MRSA-II SA-II and CC239-M CC239-MRSA-I RSA-III II clone cloness repre represente sented d 83.5% of all strains included. Previous investigations have demonstra ons trated ted the pre predom domina inance nce of the these se cl clone oness in Chi China na (28 28)), Mal Malayaysia (17 (17)), and other Asian countries (23 (23)). Surprisingly, a great proportio por tion n of hVI hVISA SA str strain ainss det detect ected ed by the met method hod emp employ loyed ed originated from South Korea (27/63 [42.9%]), and 61.4% of the MRSA strains from this country were considered hVISA. In addition, the vast majority (26/27 [96.3%]) of these hVISA strains

IA) for technical support and manuscript assistance: S. Benning, M. Castanheira, A. Costello, S. Farrell, and P. R. Rhomberg. We also thank Herminia de Lencastre and Keiichi Hiramatsu for providing S. providing S. aureus strains aureus strains HDE288 and WIS, respectively, used in this study as positive controls (SCCmec  (SCC mec  types  types V and VI) during the SCCmec  SCCmec  typing  typing procedures. This study was sponsored by the Pfizer, Inc., Specialty Care Business Unit, Coll Collegev egeville ille,, PA. JMI Labor Laboratorie atories, s, Inc. (R.E. (R.E.M., M., L.M.D L.M.D., ., D.J.F D.J.F., ., and R.N.J.) R.N.J .) rece received ived research research and educational educational grants in 2009 to 2011 from Achaogen, Aires, American Proficiency Institute (API), Anacor, Astellas, AstraZeneca, Bayer, bioMérieux, Cempra, Cerexa, Cosmo Technologies, Contrafec Contr afect, t, Cubi Cubist, st, Daii Daiichi, chi, Dipex Dipexium,Enanta, ium,Enanta, Furie Furiex, x, Glaxo GlaxoSmith SmithKline Kline,, Johnson & Johnson (Ortho McNeil), LegoChem Biosciences Inc., Meiji Seika Kaisha, Merck, Nabriva, Novartis, Paratek, Pfizer (Wyeth), PPD Therapeut Thera peutics, ics, Prem Premier ier Resea Research rch Group Group,, Remp Rempex, ex, Rib-XPharmace Rib-XPharmaceutica uticals, ls, Seachaid, Seac haid, Shion Shionogi, ogi, Shion Shionogi ogi USA, the Medi Medicine ciness Co., Thera Theravance vance,, ThermoFisher, TREK Diagnostics, Vertex Pharmaceuticals, and some other corporations.

were CC5-MRSA-II. An elevated hVISA rate (37.7%) has been previously reported by Park et al. (37 (37)) among isolates responsible for bacteremia bacteremia in a hospi hospital tal in South Korea, and sever several al studies also reported that a greater number of hVISA strains were associated with CC5-MRSA-II (11 (11,, 37  37,, 44  44,, 48  48). ). The clinical significance of hVISA remains controversial (37 ( 37,,  44  44)), but the overall rate of  hVISA hVI SA str strain ainss (14. (14.5%) 5%) obs observ erved ed in thi thiss stu study dy app appear earss ele elevat vated ed and mostly driven by a high rate noted in South Korea due to the dissemination of genetically related strains (PFGE, ASI-A). However,the hVISAhVISA-posit positive ive resul results ts obtai obtained ned here were not confir confirmed med by a second Etest macromethod testing result or population anal ysis profile-area under the curve (PAP-AUC). (PA P-AUC). Some key phenotypic characteristics were observed according to the MRSA clonal lineage. Most notably, CC239-MRSA-III strains were resistant to erythromycin, clindamycin, gatifloxacin, tetracycline, and TMP/ SMX, which has been a characteristic profile observed among isolates belonging to this clone (4 (4). Altho Although ugh USA300 strai strains ns were previously described as susceptible to fluoroquinolones and clindamycin (29 (29)), fluoroquinolone (gatifloxacin) resistance has become commonplace among these strains (29 (29,,   30 30,,   50 50)) and was confirmed confir med here (67.9% (67.9%resis resistance tance). ). In contr contrast, ast, clin clindamyc damycin in resis resis-tance remains uncommon among USA300 strains (27 (27,, 30  30)). However, this study (14.3% resistance) and results from previous reports por ts sug sugges gestt tha thatt cli clinda ndamyc mycin in res resist istanc ancee maybe eme emergi rging ng amo among ng USA300 strains (27 (27,, 50  50). ). It is important to mention that some countries, such as Hong Kong, Singapore, Germany, Greece, Poland, Spain, Turkey, the United Kingdom, South Africa, Argentina, and Colombia, contributed limited numbers of strains ( 5 isolates) to this clinical trialstudy, which whichmay may comp compromis romisee some epid epidemiol emiologica ogicall concl concluusions and/or comparison with other investigations. However, this study provides some insights regarding the MRSA population responsible for NP in most evaluated regions. In summary, the data docume doc umente nted d a cle clear ar dom domina inance nce of the CC5 lin lineag eagee and con confirm firmed ed an increased prevalence of USA300 strains causing NP in the

SomeCubist, JMI Laboratories employees are advisors and/or consultants for Astellas, Pfizer, Cempra, Cerexa-Forest, J&J, and Theravance. D.S.S. and B.S. have no potential conflicts of interest to declare.

Novemb Nov ember er 2012 2012 Vol Volume ume 50 Num Number ber 11 11

ACKNOWLEDGMENTS

We thankthe foll followingstaff owingstaff memb members ers at JMI Labor Laboratori atories es (NorthLiberty,

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