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July 5, 2010

One-Year Surveillance of Methicillin-Resistant Staphylococcus aureus Nasal Colonization and Skin and Soft Tissue Infections in Collegiate Athletes

Author Affiliations

Author Affiliations: Division of Pediatric Infectious Diseases, Department of Pediatrics (Drs Creech and Edwards, Mss Saye, Johnson, and Jimenez, and Mr McKenna), Division of Infectious Diseases, Department of Medicine, and Department of Preventive Medicine (Dr Talbot), and Division of Sports Medicine, Department of Orthopaedics (Mr Bossung and Dr Gregory), Vanderbilt University Medical Center, and Vanderbilt Children's Hospital (Drs Creech and Edwards, Mss Saye, Johnson, and Jimenez, and Mr McKenna), Nashville, Tennessee.


Copyright 2010 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2010

Arch Pediatr Adolesc Med. 2010;164(7):615-620. doi:10.1001/archpediatrics.2010.93

Objective  To determine the frequency and clinical importance of methicillin-resistant Staphylococcus aureus (MRSA) colonization in student athletes.

Design  Prospective observational cohort study.

Setting  A major university in the southeastern United States.

Participants  Student athletes participating in the men's football and women's lacrosse programs (N = 126).

Main Exposure  Monthly assessment of S aureus nasal colonization.

Main Outcome Measures  Trends in S aureus colonization over time and the occurrence of skin and soft tissue infections.

Results  Methicillin-resistant S aureus nasal colonization varied significantly through the athletic season (4%-23%), peaking during times of highest athletic activity. This increase in colonization was not associated with the development of an outbreak of skin and soft tissue infections, and no single MRSA clone emerged as a dominant isolate.

Conclusions  During the athletic season, there is a considerable burden of MRSA colonization in student athletes; however, colonization alone appears to be insufficient to trigger an outbreak of staphylococcal infections. A combination of distinct molecular characteristics in the organism and specific host factors may govern the development of staphylococcal disease.

Each year, infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are responsible for nearly 20 000 deaths in the United States alone.1 At the root of the problem is that S aureus is a ubiquitous microorganism, colonizing the anterior nares of nearly one-third of the entire human population at any given time.2,3 However, S aureus does not remain merely a commensal; rather, it is the leading cause of skin, soft tissue, and bone infections and has a spectrum of illness ranging from boils and cellulitis to infective endocarditis, necrotizing pneumonia, sepsis, and death.4 The challenge of S aureus (and therefore MRSA) is generated by 2 distinctive properties, an assortment of potent virulence factors responsible for each of these disease phenotypes and the ability to rapidly develop antimicrobial resistance, providing the organism with the tools to prosper as a commensal, thrive as a pathogen, and elude nearly all antistaphylococcal agents.57 These characteristics make S aureus one of the most important bacterial pathogens in the United States.

Since the widespread emergence of community-associated MRSA (CA-MRSA), numerous reports have suggested that sports team participants, particularly those involved in contact sports, may be at increased risk for infections with CA-MRSA.812 In a recent survey of the National Athletic Trainers Association, more than half of all athletic trainers (53%) reported treating MRSA infections in their athletes, the vast majority of which (92%) were skin and soft tissue infections.13 In 2003, the Centers for Disease Control and Prevention highlighted the problem of MRSA in wrestlers, fencers, and football players.14 While each of these reports provided important information regarding the characteristics of infected athletes, they did not provide longitudinal data characterizing the frequency of nasal colonization, the rate of CA-MRSA disease in those who were colonized, or the differences between those who remain asymptomatically colonized and those who develop disease.

To provide such a longitudinal assessment, we systematically sampled collegiate athletes for S aureus nasal colonization (including MRSA) and prospectively assessed them for the development of skin and soft tissue infections. We present the molecular features of the MRSA isolates recovered from the participants and the risk factors associated with colonization and disease.


Student athletes participating in the Vanderbilt University men's football and women's lacrosse teams were invited to participate in the study. While the entire varsity athletic program at Vanderbilt comprises nearly 400 individuals aged 18 to 24 years, the football and lacrosse teams number 125 students and compete in Division I of the National Collegiate Athletic Association's Southeastern Conference (football) and the American Lacrosse Conference (women's lacrosse). Subjects were eligible to participate in the study on entrance to training camps, occurring in both the spring (March) and fall (August), and they were asked to remain in the study for the academic year, until completion of undergraduate education or cessation of involvement in the varsity athletic program. The Vanderbilt University Medical Center institutional review board and university counsel approved the study.

After informed consent was obtained, a questionnaire was administered to the athletes to assess potential risk factors for nasal colonization. The questionnaire included items regarding position on the team, history of skin or soft tissue infections, history of staphylococcal infections, recent antibiotic use, recent hospitalization or surgery, history of chronic skin disorders, and exposure to individuals with confirmed MRSA disease. Nasal swabs were collected each month by study personnel by moistening Culturette swabs (BD, Franklin Lakes, New Jersey) with sterile media, rotating the swab in the anterior nares, placing the swabs in liquid Amies medium (BD Culturette Plus), and promptly delivering them to the laboratory.

In addition to nasal screening visits, all subjects were repeatedly instructed to alert their athletic trainer or sports medicine physician if signs or symptoms of skin or soft tissue infections developed. These symptoms included redness of the skin, development of a pustule or other fluid collection, and poorly healing, tender, or unusually erythematous abrasions. When these symptoms were reported, study personnel were contacted and all skin and soft tissue infections, as diagnosed by team physicians and study personnel, were cultured, where possible, and antibiotics were prescribed at the discretion of the team physicians. Nasal decolonization strategies were not performed.

Once in the laboratory, swab samples were placed in tryptic soy broth with 6.5% sodium chloride. After incubation at 37°C for 18 hours, an aliquot was plated onto paired mannitol salt agar plates, with and without 4 μg/mL of oxacillin (Hardy Diagnostics, Santa Maria, California), and incubated at 37°C for 48 hours. After an additional 18 hours at room temperature, plates were inspected for yellow colonies indicative of mannitol fermentation, characteristic of S aureus. After subculturing onto blood agar plates, rapid latex agglutination testing for clumping factor and protein A was performed on all isolates (Staphaurex Plus; Remel, Lenexa, Kansas) and positive isolates were stored at −80°C for further characterization.

Any colonies growing in the presence of oxacillin were considered to be putative MRSA isolates and underwent confirmation of the presence of the mecA gene by polymerase chain reaction.5 Isolates confirmed to be MRSA underwent staphylococcal cassette chromosome mec (SCCmec) typing using the multiplex strategy of Oliveira and de Lencastre15; however, for those strains unable to be characterized by the multiplex strategy, ccr and mec complex typing were performed as previously described.16 Genomic DNA was used as a template for polymerase chain reaction detection of the nuclease gene (specific to S aureus), the staphylococcal-specific cytolytic toxin Panton-Valentine leukocidin (PVL), and the arginine catabolic element, using previously validated primers.1719 Repetitive-element, sequence-based polymerase chain reaction (DiversiLab System; Biomerieux, Durham, North Carolina) was used to determine genetic relatedness between strains and classification of genotype (eg, USA100, USA300).2022

Using a conservative baseline MRSA colonization rate of 6%, and estimating that the frequency of MRSA colonization would increase 3-fold during the course of the season, 114 subjects were needed (from football and lacrosse teams combined) to adequately detect a difference between colonization rates (α = .05; β = 0.8; Pearson χ2 method). Pearson χ2 method was used to measure differences in colonization rates between the off-season (limited sports-related activities), preseason (intense practice sessions but no competitive activities), regular season (the time of highest activity), and postseason (returning to limited sports-related activities). Multivariate analysis for potential risk factors for MRSA colonization at any time was performed by logistic regression. All analyses were performed using Stata 10.0 (StataCorp, College Station, Texas).


To determine the frequency of S aureus colonization over time, nasal swabs were collected from 100 subjects, representing 98% of the entire football team, over 8 sampling periods. At any one time, S aureus nasal colonization rates ranged from 12% to 30%, with the lowest colonization rates observed in the summer off-season and the highest observed during the football season (Figure 1). Overall, MRSA nasal colonization was detected in as few as 4% of participants, during the summer off-season, and as many as 19% at the end of the regular football season. The MRSA colonization rates during the regular football season were significantly higher than in spring training (16.5% vs 8.4%; P = .003), the off-season (16.5% vs 4.4%; P = .004), or postseason (16.5% vs 7.7%; P = .04).

Figure 1.
Image not available

Staphylococcal colonization (by month) in a men's collegiate football team. Monthly cultures are divided into spring training (March/April), the off-season (June/July), the regular football season (August-October), and the postseason (December). Monthly results are expressed graphically while aggregate colonization rates are expressed below each season. Double hash marks represent months in which nasal swabs were not performed. The frequency of methicillin-resistant Staphylococcus aureus (MRSA) colonization during the football season was significantly higher than in spring training (16.5% vs 8.4%; P = .003), the off-season (16.5% vs 4.4%; P = .004), and the postseason (16.5% vs 7.7%; P = .04).

To define risk factors associated with staphylococcal nasal carriage, data from each subject's baseline questionnaire and monthly updates were linked to his carriage pattern over time. A majority of subjects (54%) had at least 1 positive nasal culture for S aureus during the study period; 37% had at least 1 positive culture for MRSA. There were no differences in the rates of S aureus nasal colonization, either methicillin-susceptible S aureus or MRSA, by race (P = .97), college year (P = .61), football position (P = .97), history of antibiotic use within 6 months (P = .85), or hospitalization within 12 months (P = .06) (Table). Multivariate logistic regression, including tests for interaction, revealed no significant differences based on these characteristics. Seventy-nine players (79%) had 2 or fewer positive cultures for S aureus (of 8 sample periods), while 10% of players had 5 or more positive cultures. There were no differences in the number of positive cultures based on race, college year, football position, history of antibiotic use, or history of hospitalization.

Image not available
Demographic Characteristics of Men's Football Team

To determine if the colonization characteristics observed in the football cohort were generalizeable to other student athletes, we enrolled 26 women from the women's lacrosse team, representing 100% of the group. Nasal swabs were obtained during both the winter and spring lacrosse seasons, but the team members did not remain on campus during the summer; therefore, colonization was assessed over only 6 sample periods. S aureus nasal colonization rates ranged from 28% to 39% of subjects at any one time, with the lowest frequency of colonization observed during the winter postseason and the highest, during the fall season (Figure 2). The MRSA nasal colonization rates ranged from 11% to 23% of subjects, with 2 relative peaks, 1 during the spring season and 1 during the fall season. Despite the relative increase in colonization rates during these 2 sample periods, overall differences in nasal colonization across all points and between peak and nadir did not achieve statistical significance (23.1% [fall season] vs 11.5% [preseason]; P = .36). In addition, there were no differences in the number of positive methicillin-susceptible S aureus or MRSA cultures based on race, college year, position, history of antibiotic use, or history of hospitalization.

Figure 2.
Image not available

Staphylococcal colonization (by month) in a women's collegiate lacrosse team. Monthly cultures are divided into the preseason (January), spring season (February-April), fall season (September/October), and postseason (November). Monthly results are expressed graphically while aggregate colonization rates are expressed below each season. Double hash marks represent months in which nasal swabs were not obtained. The frequency of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization was highest in the fall season (23.1%) and lowest in the preseason (11.5%), though differences between seasons were not statistically significant (23.1% vs 11.5%; P = .36).


To identify whether staphylococcal colonization portends a higher risk for infection, we assessed all skin and soft tissue infections that were consistent with staphylococcal disease. Five individuals experienced infections, 4 from the football cohort and 1 from the lacrosse cohort. Two of these subjects (1 from the football team, 1 from the lacrosse team) had pustular lesions that spontaneously drained prior to culturing. Surface swab cultures of the lesions did not reveal a pathogen (1 of these subjects had MRSA nasal colonization at the sample time prior to the infection). Two football players had carbuncles drained within days of each other and both grew Proteus mirabilis. Neither of the subjects had evidence of staphylococcal nasal colonization immediately before or after the infection occurrence. The last of these 5 individuals with skin infections developed recurrent MRSA furunculosis during football spring training. Nasal cultures were negative for MRSA before and after furuncles developed; however, during the football season, he developed asymptomatic MRSA nasal colonization.


To study the discrepancy between high colonization rates and the infrequent incidence of skin and soft tissue infections, we characterized the molecular feature of the nasal and infecting MRSA strains. Each of the 73 MRSA colonizing isolates possessed the mecA gene, characteristic of MRSA, and the S aureus–specific nuc gene. None of the carriage isolates possessed genes encoding PVL or the arginine catabolic element. Further analysis of 53 viable strains revealed that 43 (81.1%) possessed a type IV SCCmec, 8 possessed a type II SCCmec (15.1%), 1 possessed a type III cassette (1.8%), and 1 possessed a type V cassette (1.8%). There was considerable heterogeneity between strains, with the most common genetic lineages being USA200 (20.8%), USA900 (18.9%), USA300 (9.4%), USA400 (9.4%), USA600 (9.4%), and USA800 (9.4%). The single MRSA isolate recovered from an active infection was characterized as a PVL+, SCCmec type IV, USA300 CA-MRSA.


In this study of healthy collegiate athletes, we demonstrate that MRSA nasal colonization rates increased significantly during the course of the athletic season. This increase was not due to the emergence of a single MRSA strain; rather, there was significant heterogeneity among nasal MRSA isolates. Despite the frequency of MRSA colonization in these student athletes, MRSA infections were uncommon, suggesting that colonization alone may be insufficient to initiate a staphylococcal outbreak.

Of particular interest is that the frequency of MRSA nasal colonization during the off-season and preseason was very similar to the frequency of MRSA carriage in other groups that we have reported in our region.5 Yet, in both the football and lacrosse teams, colonization significantly increased during the regular season, implying that factors unique to this time—whether exposure related (encountering other teams with their own MRSA colonization rates, shared equipment, or uniforms) or host related (more frequent abrasions)—play an important role in the dynamics of staphylococcal colonization. It seems unlikely that this observation is due to calendar seasonality alone since the lacrosse team experienced 2 MRSA carriage peaks, during both their fall and spring seasons.

To our knowledge, this is the first longitudinal study to assess nasal MRSA colonization in competitive sports teams in a nonoutbreak scenario. Kazakova et al,11 investigating a CA-MRSA outbreak in a professional football team, detected methicillin-susceptible S aureus colonization in 42% of players and staff; however, MRSA colonization could not be detected. But, the institution of effective infection control, improved hygiene measures, and the use of antimicrobial agents prior to sampling could have confounded their assessment. More recently, Romano et al8 reported 3 years' experience with CA-MRSA skin and soft tissue infections in a collegiate football team. During a year in which skin and soft tissue infections were occurring frequently, nasal cultures were performed 1 month into the regular football season. Methicillin-resistant S aureus nasal carriage was detected in 6.6% of the team, a higher rate than was observed at the beginning of the next year's season (2.9%), suggesting an effect from either timing in the season or the nature of the outbreak itself. Molecular characterization of the isolates was not performed in their study; thus, it is unclear whether nasal and skin and soft tissue infection strains were similar.

We propose that the disparity between high colonization rates and the low incidence of CA-MRSA skin and soft tissue infection in our cohort is due primarily to the relatively low frequency of PVL+, SCCmec type IV strains of USA300 CA-MRSA among carriage isolates. While the precise role of PVL in the pathogenesis of CA-MRSA infections remains unclear,23,24 strains that possess PVL are strongly associated with a variety of clinical phenotypes, such as osteomyelitis, necrotizing pneumonia, and furunculosis.18,25 Previous reports suggest that PVL is nearly ubiquitous in SCCmec type IV strains of MRSA26; however, more recent studies suggest that a much larger pool of SCCmec type IV, PVL strains exist, particularly in asymptomatic carriage.27 Wang et al,27 studying colonization in patients with end-stage renal disease, found that only 38.5% of SCCmec type IV strains were positive for PVL, a finding consistent with previous studies.5 Regardless of the role of PVL in pathogenesis, strains that possess this cytolytic toxin may possess other characteristics, such as the arginine catabolic element or phenol-soluble modulins that enable them to more effectively cause disease than PVL strains.

A potential caveat to our study is that the monthly frequency of nasal swabs does not allow us to determine which subjects are persistent carriers, intermittent carriers, or noncarriers,2 a characterization typically made by weekly cultures over a 12-week period. Persistent staphylococcal carriers might be a source for continued transmission of S aureus in groups such as athletic teams; therefore, future studies should consider whether more frequent cultures (eg, weekly) provide a more precise assessment of colonization dynamics. In addition, we only assessed colonization in the anterior nares rather than sampling the axilla, perineum, or oropharynx; as a result, we may have underestimated the true frequency of colonization in our cohort. For example, Nilsson and Ripa28 described preferential throat carriage of MRSA in a cohort of health care workers and hospitalized patients. Of 125 patients screened for both throat and nasal carriage in their study, 80 of 125 (64%) were identified by nasal cultures alone; however, an additional 24 subjects were identified (104 of 125 [83%]) with throat cultures alone. Whether the dynamics of oropharyngeal colonization over time are similar to that in the anterior nares remains unknown.

In summary, in this cohort of collegiate athletes, there were surprisingly high MRSA nasal colonization rates that reached their peak during highest athletic activity within the season. However, these high rates of MRSA nasal colonization alone were insufficient to trigger an outbreak of skin and soft tissue infections in this cohort. The potential exists for other unknown factors, including the molecular characteristics of carriage strains, to govern the development of a disease outbreak. Additional longitudinal studies of staphylococcal colonization and disease are critically needed to determine the most effective means of primary prevention of this potentially devastating pathogen.

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Article Information

Correspondence: C. Buddy Creech, MD, MPH, Pediatric Infectious Diseases, Vanderbilt University School of Medicine, Children's Hospital at Vanderbilt, 1161 21st Ave S, CCC-5311 MCN, Nashville, TN 37232-2573 (

Accepted for Publication: December 10, 2009.

Author Contributions:Study concept and design: Creech, Talbot, Gregory, and Edwards. Acquisition of data: Creech, Saye, McKenna, Johnson, Jimenez, and Bossung. Analysis and interpretation of data: Creech, Saye, McKenna, Jimenez, and Talbot. Drafting of the manuscript: Creech and Bossung. Critical revision of the manuscript for important intellectual content: Creech, Saye, McKenna, Johnson, Jimenez, Talbot, Gregory, and Edwards. Statistical analysis: Creech. Obtained funding: Creech. Administrative, technical, and material support: Creech, Saye, Johnson, Jimenez, Bossung, and Gregory. Study supervision: Talbot and Edwards.

Financial Disclosure: Dr Creech has received research grant support from Pfizer, Merck, and Cubist Pharmaceuticals and has served on advisory boards for Pfizer and Novartis Vaccines.

Funding/Support: This work was funded through National Institutes of Health grants K12 RR017697 (Dr Creech) and K23 AI074830 (Dr Creech).

Klevens  RMMorrison  MANadle  J  et al. Active Bacterial Core surveillance (ABCs) MRSA Investigators, Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA 2007;298 (15) 1763- 1771
Kluytmans  Jvan Belkum  AVerbrugh  H Nasal carriage of Staphylococcus aureus: epidemiology, underlying mechanisms, and associated risks. Clin Microbiol Rev 1997;10 (3) 505- 520
Nouwen  JLOtt  AKluytmans-Vandenbergh  MF  et al.  Predicting the Staphylococcus aureus nasal carrier state: derivation and validation of a “culture rule”. Clin Infect Dis 2004;39 (6) 806- 811
Mandell  GLDouglas  RGBennett  JEDolin  R Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 6th ed. Philadelphia, PA Elsevier Churchill Livingstone2005;
Creech  CB  IIKernodle  DSAlsentzer  AWilson  CEdwards  KM Increasing rates of nasal carriage of methicillin-resistant Staphylococcus aureus in healthy children. Pediatr Infect Dis J 2005;24 (7) 617- 621
Kaplan  SLHulten  KGGonzalez  BE  et al.  Three-year surveillance of community-acquired Staphylococcus aureus infections in children. Clin Infect Dis 2005;40 (12) 1785- 1791
Chambers  HF Community-associated MRSA—resistance and virulence converge. N Engl J Med 2005;352 (14) 1485- 1487
Romano  RLu  DHoltom  P Outbreak of community-acquired methicillin-resistant Staphylococcus aureus skin infections among a collegiate football team. J Athl Train 2006;41 (2) 141- 145
Cohen  PR Cutaneous community-acquired methicillin-resistant Staphylococcus aureus infection in participants of athletic activities. South Med J 2005;98 (6) 596- 602
Nguyen  DMMascola  LBrancoft  E Recurring methicillin-resistant Staphylococcus aureus infections in a football team. Emerg Infect Dis 2005;11 (4) 526- 532
Kazakova  SVHageman  JCMatava  M  et al.  A clone of methicillin-resistant Staphylococcus aureus among professional football players. N Engl J Med 2005;352 (5) 468- 475
Begier  EMFrenette  KBarrett  NL  et al. Connecticut Bioterrorism Field Epidemiology Response Team, A high-morbidity outbreak of methicillin-resistant Staphylococcus aureus among players on a college football team, facilitated by cosmetic body shaving and turf burns. Clin Infect Dis 2004;39 (10) 1446- 1453
Brinsley-Rainisch  KGoding  ASinkowitz-Cochran  RPearson  MHageman  Jthe National Athletic Trainers' Association, MRSA infections in athletics: perceptions and practices of certified athletic trainers.  Poster presented at the Society for Healthcare Epidemiology of America 17th Annual Meeting April 15, 2007 Baltimore, Maryland
Centers for Disease Control and Prevention (CDC), Methicillin-resistant Staphylococcus aureus infections among competitive sports participants—Colorado, Indiana, Pennsylvania, and Los Angeles County, 2000-2003. MMWR Morb Mortal Wkly Rep 2003;52 (33) 793- 795
Oliveira  DCde Lencastre  H Multiplex PCR strategy for rapid identification of structural types and variants of the mec element in methicillin-resistant Staphylococcus aureusAntimicrob Agents Chemother 2002;46 (7) 2155- 2161
Kondo  YIto  TMa  XX  et al.  Combination of multiplex PCRs for staphylococcal cassette chromosome mec type assignment: rapid identification system for MEC, CCR, and major differences in junkyard regions. Antimicrob Agents Chemother 2007;51 (1) 264- 274
Chesneau  OAllignet  Jel Solh  N Thermonuclease gene as a target nucleotide sequence for specific recognition of Staphylococcus aureusMol Cell Probes 1993;7 (4) 301- 310
Lina  GPiemont  YGodail-Gamot  F  et al.  Involvement of Panton-Valentine leukocidin-producing Staphylococcus aureus in primary skin infections and pneumonia. Clin Infect Dis 1999;29 (5) 1128- 1132
Diep  BAGill  SRChang  RF  et al.  Complete genome sequence of USA300, an epidemic clone of community-acquired methicillin-resistant Staphylococcus aureusLancet 2006;367 (9512) 731- 739
Shutt  CKPounder  JIPage  SRSchaecher  BJWoods  GL Clinical evaluation of the DiversiLab microbial typing system using repetitive-sequence-based PCR for characterization of Staphylococcus aureus strains. J Clin Microbiol 2005;43 (3) 1187- 1192
Tenover  FCMcDougal  LKGoering  RV  et al.  Characterization of a strain of community-associated methicillin-resistant Staphylococcus aureus widely disseminated in the United States. J Clin Microbiol 2006;44 (1) 108- 118
McDougal  LKSteward  CDKillgore  GEChaitram  JMMcAllister  SKTenover  FC Pulsed-field gel electrophoresis typing of oxacillin-resistant Staphylococcus aureus isolates from the United States: establishing a national database. J Clin Microbiol 2003;41 (11) 5113- 5120
Voyich  JMOtto  MMathema  B  et al.  Is Panton-Valentine leukocidin the major virulence determinant in community-associated methicillin-resistant Staphylococcus aureus disease? J Infect Dis 2006;194 (12) 1761- 1770
Labandeira-Rey  MCouzon  FBoisset  S  et al.  Staphylococcus aureus Panton-Valentine leukocidin causes necrotizing pneumonia. Science 2007;315 (5815) 1130- 1133
Bocchini  CEHulten  KGMason  EO  JrGonzalez  BEHammerman  WAKaplan  SL Panton-Valentine leukocidin genes are associated with enhanced inflammatory response and local disease in acute hematogenous Staphylococcus aureus osteomyelitis in children. Pediatrics 2006;117 (2) 433- 440
Vandenesch  FNaimi  TEnright  MC  et al.  Community-acquired methicillin-resistant Staphylococcus aureus carrying Panton-Valentine leukocidin genes: worldwide emergence. Emerg Infect Dis 2003;9 (8) 978- 984
Wang  CYWu  VCChen  YMSu  CTWu  KDHsueh  PR Nasal carriage of methicillin-resistant Staphylococcus aureus among patients with end-stage renal disease. Infect Control Hosp Epidemiol 2009;30 (1) 93- 94
Nilsson  PRipa  T Staphylococcus aureus throat colonization is more frequent than colonization in the anterior nares. J Clin Microbiol 2006;44 (9) 3334- 3339