Colonization With Methicillin-resistant Staphylococcus aureus and Risk for Infection Among Asymptomatic Athletes: A Systematic Review and Metaanalysis

Staphylococcus aureus: No ticket for the Paris 2024 Olympic Games!

Athletes are vulnerable to Staphylococcus aureus infections due to skin-to-skin contact and skin abrasions during training and competitions involving sharied sport equipment or toiletries, which promote the spread of the bacteria between athletes and within sport teams. This results not only in higher prevalence of S.aureus carriage among athletes compared to the general population, but also in outbreaks of infections, particularly skin infections, within sports teams. To limit the spread of S. aureus among athletes, a decolonization protocol can be applied when clustered cases of S. aureus infections occur, especially if Panton-Valentine leukocidin-producing strains are implicated. Finally, to avoid exposing athletes to S.aureus transmission/colonization, it is recommended to establish strict and clearly formulated individual and collective hygiene rules and to regularly disinfect shared sports equipment.

Eradication of community-onset Methicillin-resistant Staphylococcus aureus carriage: a narrative review

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization increases infection risk in both patients and healthy individuals. Decolonization therapy has been proven to reduce S. aureus infections, but data on the effectiveness of individual decolonization strategies in community-onset MRSA carriage are scarce.

OBJECTIVES

The aim of this narrative review was to summarize the evidence on strategies for the elimination of MRSA colonization in community-onset MRSA carriers.

SOURCES

PubMed database was searched for studies on MRSA eradication, from inception to July 2023.

CONTENT

Topical therapy is proven to be effective in nasal-only carriage and in temporary load reduction. Mupirocin nasal ointment in combination with chlorhexidine body wash is highly effective in nasal-only MRSA carriers in the community as well. In patients with extra-nasal colonization, addition of orally administered antibiotics likely increases success rates compared with topical therapy alone. Studies on systemic treatment of extra-nasal MRSA decolonization are subject to a high heterogeneity of antimicrobial agents, treatment duration, and control groups. The majority of evidence supports the use of a combination of topical therapy with rifampin and another antimicrobial agent. Decolonization treatment with probiotics is a promising novel non-antibiotic strategy. However, achieving long-term decolonization is more likely in countries with low MRSA prevalence, given the risk of recolonization in a context of high MRSA prevalence.

IMPLICATIONS

The decision to pursue community-onset MRSA eradication treatment in the individual patient should be based on the combination of the treatment objective (short-term bacterial load reduction in health care settings vs. long-term eradication in community settings), and the likelihood of successful decolonization. The latter is influenced by both individual risk factors for treatment failure, and the risk of recolonization. The addition of a combination of systemic antibiotics is rational for extra-nasal long-term decolonization. To determine the most effective systemic antimicrobial agents in MRSA decolonization, more research is needed.

Tricuspid Valve Endocarditis Due to Methicillin-Resistant Staphylococcus aureus in a Previously Healthy Young Patient without a Drug Abuse History: A Case Report and a Review of the Literature

Right-sided infective endocarditis due to methicillin-resistant Staphylococcus aureus (MRSA) is strongly associated with intravenous drug abuse, congenital heart disease, or previous medical treatment and is rare in healthy patients without a history of drug abuse. Here, we present a case of an 18-year-old male with no drug abuse history and no medical burden who was diagnosed with MRSA tricuspid valve endocarditis. Due to initial symptoms which indicated community-acquired pneumonia and radiological finding of interstitial lesions, empiric therapy with ceftriaxone and azithromycin was started. After the detection of Gram-positive cocci in clusters in several blood culture sets, endocarditis was suspected, and flucloxacillin was added to the initial therapy. As soon as methicillin resistance was detected, the treatment was switched to vancomycin. Transesophageal echocardiography established the diagnosis of right-sided infective endocarditis. A toxicological analysis of hair was carried out, and no presence of narcotic drugs was found. After six weeks of therapy, the patient was fully recovered. Exceptionally, tricuspid valve endocarditis can be diagnosed in previously healthy people who are not drug addicts. As the clinical presentation commonly resembles a respiratory infection, a misdiagnosis is possible. Although MRSA rarely causes community-acquired infections in Europe, clinicians should be aware of this possibility.

Characteristics of Virulent ST5-SCCmec II Methicillin-Resistant Staphylococcus aureus Prevalent in a Surgery Ward

Objective

To investigate the transmission pathway of a MRSA prevalence in a pancreatic surgery ward in a Chinese teaching hospital.

Methods

Molecular epidemiology investigations were carried out combined PFGE, MLST, SCCmec typing and whole-genome sequencing for 20 successive MRSA isolates (2 isolates from the ward environment). Resistance and virulence genes were detected using specific PCR. Bacterial identification and AST were performed using the Vitek 2 Compact System. Clinical data of enrolled cases were retrieved from electronic case records.

Results

From January 2020 to May 2020, successive isolated 20 MRSA strains were clarified to 2 PFGE patterns (A = 19, B = 1) in the ward. Both isolates from environment and patients belonged to sequence type ST5-SCCmec II-spa type t311. MRSA-related resistance genes mecA, blaZ, ermA, ant(4')-Ia and norA were found in each clone. All 20 isolates carried tst, hlg, hla, eta, eap, fnbA and seo virulence genes, other virulence genes such as sea, sec, seb, seg, sei, sem, sen, ebpS and fnbB were also found in partial stains. All patients had fever symptom, 27.8% were accompanied by diarrhea, 88.9% had undergone surgery or invasive procedures within 30 days. Finally, 94.4% of these patients recovered.

Conclusion

This study confirmed a prevalence of ST5-MRSA-II-t311 clone in a surgery ward, indicated MRSA is a risk factor for post-surgery nosocomial infection and hand hygiene and environmental surveillance should not be ignored.

The Identification and Treatment of Common Skin Infections

Skin conditions are a common problem addressed by medical providers. Up to 25% of individuals in the United States will seek attention for these conditions each year. The same problem occurs in the athletic training room, where athletes with infectious skin conditions can be seen. Most conditions are simple and can be treated without concern for spread to susceptible athletes. However, others can be quite serious and spread rapidly through a team and opponents during competition. Knowledge of the different types of skin infections is necessary to help treat these athletes and prevent spread to others. With proper diagnosis and treatment, certified athletic trainers can keep the athlete off the field of play for a minimum period and prevent transmission.

Current and emerging drug treatment strategies to tackle invasive community-associated methicillin-resistant Staphylococcus aureus (MRSA) infection: what are the challenges?

INTRODUCTION

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections represent a leading cause of purulent skin and soft tissue infections in some geographical regions. Traditionally, 'old antibiotics' such as trimethoprim-sulfamethoxazole, tetracyclines, clindamycin, chloramphenicol,vancomycin, and teicoplanin have been used to treat these infections, but these were often associated with low efficacy and excessive side effects and toxicity, especially nephrotoxicity. Along with the development of new compounds, the last decade has seen substantial improvements in the management of CA-MRSA infections.

AREAS COVERED

In this review, the authors discuss the current and emerging drug treatment strategies to tackle invasive CA-MRSA infections. Articles reported in this review were selected from through literature searches using the PubMed database.

EXPERT OPINION

The availability of new drugs showing a potent in vitro activity against CA-MRSA represents a unique opportunity to face the threat of resistance while potentially reducing toxicity. All these compounds represent promising options to enhance our antibiotic armamentarium. However, data regarding the use of these new drugs in real-life studies are limited and their best placement in therapy and in terms of optimization of medical resources and balance of cost-effectiveness requires further investigation.

The association between antibiotics and community-associated Staphylococcus aureus colonization in the United States population: Analysis of the National Health and Nutrition Examination Survey (NHANES)

Staphylococcus aureus nasal colonization is a seriously opportunistic infection. However, there is a lack of research of relationship between antibiotics and S aureus colonization in the general population. Through a cross-sectional investigation, this study intends to establish the parameters related to S aureus nasal colonization, specifically the function antibiotics play in colonization. The key information from 2001 to 2004 was abstracted from National Health and Nutrition Examination Survey (NHANES), including information on general demographics, health care status, antibiotic prescription, diabetes, alcohol consumption, and tobacco smoke exposure. The participants colonized with methicillin-susceptible S aureus (MSSA), or methicillin-resistant S aureus (MRSA) were defined as the case group, and the control group was subjects without positive S aureus colonization. Univariate and multivariate logistic regression models were used to identify the variables associated with MSSA and MRSA colonization. The records of 18,607 individuals were included, involving 13,205 cases without S aureus colonization, 5195 cases with MSSA, and 207 cases with MRSA. In the multivariate logistic regression analysis, the risk of MSSA colonization was significantly reduced with fluoroquinolone use (75% risk reduction, P = .02), sulfonamide use (98% risk reduction, P < .01), tetracycline use (81% risk reduction, P < .01) and antibiotic combination therapy (risk reduction 76%, P < .01). Female, race and total household size were strongly associated with MSSA carriage. On the other hand, regarding MRSA colonization, fluoroquinolone use, long-term care, and former smoker were positively associated with MRSA colonization, while high income was negatively associated with MRSA colonization. More proper use of broad-spectrum antibiotics contributes to reducing MSSA colonization. Former smokers should also practice better personal hygiene to limit the possibility of MRSA colonization.

Nasal microbiota evolution within the congregate setting imposed by military training

The human microbiome is comprised of a complex and diverse community of organisms that is subject to dynamic changes over time. As such, cross-sectional studies of the microbiome provide a multitude of information for a specific body site at a particular time, but they fail to account for temporal changes in microbial constituents resulting from various factors. To address this shortcoming, longitudinal research studies of the human microbiome investigate the influence of various factors on the microbiome of individuals within a group or community setting. These studies are vital to address the effects of host and/or environmental factors on microbiome composition as well as the potential contribution of microbiome members during the course of an infection. The relationship between microbial constituents and disease development has been previously explored for skin and soft tissue infections (SSTIs) within congregate military trainees. Accordingly, approximately 25% of the population carries Staphylococcus aureus within their nasal cavity, and these colonized individuals are known to be at increased risk for SSTIs. To examine the evolution of the nasal microbiota of U.S. Army Infantry trainees, individuals were sampled longitudinally from their arrival at Fort Benning, Georgia, until completion of their training 90 days later. These samples were then processed to determine S. aureus colonization status and to profile the nasal microbiota using 16S rRNA gene-based methods. Microbiota stability differed dramatically among the individual trainees; some subjects exhibited great stability, some subjects showed gradual temporal changes and some subjects displayed a dramatic shift in nasal microbiota composition. Further analysis utilizing the available trainee metadata suggests that the major drivers of nasal microbiota stability may be S. aureus colonization status and geographic origin of the trainees. Nasal microbiota evolution within the congregate setting imposed by military training is a complex process that appears to be affected by numerous factors. This finding may indicate that future campaigns to prevent S. aureus colonization and future SSTIs among high-risk military trainees may require a ‘personalized’ approach.

Locally delivered adjuvant biofilm-penetrating antibiotics rescue impaired endochondral fracture healing caused by MRSA infection

Infection is a devastating complication following an open fracture. We investigated whether local rifampin-loaded hydrogel can combat infection and improve healing in a murine model of methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. A transverse fracture was made at the tibia midshaft of C57BL/6J mice aged 10-12 weeks and stabilized with an intramedullary pin. A total of 1 × 106 colony-forming units (CFU) of MRSA was inoculated. A collagen-based hydrogel containing low-dose (60 μg) and high-dose (300 μg) rifampin was applied before closure. Postoperative treatment response was assessed through bacterial CFU counts from tissue and hardware, tibial radiographs and microcomputed tomography (μCT), immunohistochemistry, and histological analyses. All untreated MRSA-infected fractures progressed to nonunion by 28 days with profuse MRSA colonization. Infected fractures demonstrated decreased soft callus formation on safranin O stain compared to controls. Areas of dense interleukin-1β stain were associated with poor callus formation. High-dose rifampin hydrogels reduced the average MRSA load in tissue (p < 0.0001) and implants (p = 0.041). Low-dose rifampin hydrogels reduced tissue bacterial load by 50% (p = 0.021). Among sterile models, 88% achieved union compared to 0% of those infected. Mean radiographic union scale in tibia scores improved from 6 to 8.7 with high-dose rifampin hydrogel (p = 0.024) and to 10 with combination local/systemic rifampin therapy (p < 0.0001). μCT demonstrated reactive bone formation in MRSA infection. Histology demonstrated restored fracture healing with bacterial elimination. Rifampin-loaded hydrogels suppressed osteomyelitis, prevented implant colonization, and improved healing. Systemic rifampin was more effective at eliminating infection and improving fracture healing. Further investigation into rifampin-loaded hydrogels is required to correlate these findings with clinical efficacy.

A risk as an infection route: Nasal colonization of methicillin-resistant Staphylococcus aureus USA300 clone among contact sport athletes in Japan

Panton-Valentine leukocidin (PVL)-positive USA300 clone is a highly pathogenic and global epidemic community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clone. Athletes are particularly vulnerable to CA-MRSA infection because of the frequency of skin trauma, close-contact situations, and sharing of equipment that is customary in the athletic setting. We experienced a case of Japanese collegiate football player with septic pulmonary emboli secondary to infectious iliofemoral deep venous thrombosis caused by the USA300 clone. Here, we screened the nasal carriage of USA300 clone colonization among asymptomatic teammate of the patient to elucidate the infection route. Among 69 nasal samples, CA-MRSA strains were found in 5.8% (four samples). Molecular epidemiological analyses showed that three of the CA-MRSA strains were USA300 clone. Furthermore, pulsed-field gel electrophoresis revealed that all nasal USA300 clones showed 100% identity with the USA300 clone isolated from their teammate with critical infection. Our findings indicate that nasal colonization of the PVL-positive CA-MRSA, especially USA300 clone, pose a threat among contact sport athletes in Japan likewise other countries. An immediate infection control strategy for contact sport athletes is necessary to prevent outbreaks of PVL-positive CA-MRSA infections.

The Fate of Methicillin-Resistant Staphylococcus aureus in a Synthetic Turf System

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for one-third of infectious outbreaks reported among competitive athletes at high school and collegiate levels of competition, while the frequency of infections among National Football League players is nearly 400-fold higher than in the general population. The increased prevalence of MRSA infections among such athletes necessitates the study of football-specific environments as MRSA reservoirs.

HYPOTHESIS

The recovery and viability of MRSA will differ between turf infill and turf fibers.

STUDY DESIGN

Descriptive laboratory study.

LEVEL OF EVIDENCE

Level 4.

METHODS

Each of 6 infill types and 3 turf fiber types were inoculated with MRSA, sacrificed over time, and enumerated after bacteria extraction and dilution plating to determine the incubation time at which 50% of inoculated MRSA are recoverable and viable (here termed A₅₀). The role of infill toxicity on MRSA survival was assessed using a dialysis assay.

RESULTS

On average, MRSA was available for up to 96 hours on infill (average A₅₀: 13 hours) and 24 hours on turf fibers (A₅₀: 4 hours) (P < 0.001). The A₅₀ for each infill type was also variable among infill groups (P < 0.001), averaging 2 hours (ethylene propylene diene monomer [EPDM] rubber), 7 hours (cork-based material), 9 hours (polymer-coated materials), 12 hours (crumb rubber), 13 hours (thermoplastic elastomer [TPE] rubber), and 27 hours (sands). MRSA remained available on slit-film and nylon fiber types for 12 hours postdeposition and for 24 hours on monofilament fibers. Toxicity assays showed that over 90% of MRSA cells remained viable after 6 hours of exposure to cork infill and sands, while 79%, 71%, 68%, and 17% of MRSA remained viable after exposure to polymer-coated materials, crumb rubber, TPE rubber, and EPDM rubber, respectively. Our data also indicated that organic and sand infills exhibited minimal toxicity to MRSA, while high relative toxicity drives limited MRSA availability in EPDM rubber infill.

CONCLUSION

MRSA recovery and viability varied among infill types but not among differing turf blades.

CLINICAL RELEVANCE

The results of this study can inform appropriate athlete and field management practices.

First Report of Fatal Infection Caused by Community-acquired Methicillin-resistant Staphylococcus aureus USA300 Clone in a Collegiate Athlete

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is prevalent around the world and is a causative agent of skin and soft tissue infections in healthy individuals. Particularly, Panton-Valentine leukocidin (PVL)-positive CA-MRSA strains occasionally cause life-threatening infections, such as septic pulmonary emboli (SPE) and infectious endocarditis. However, severe infections caused by PVL-positive CA-MRSA strains have rarely been reported in Japan. For the first time, this study reports the case of a 20-year-old Japanese college athlete with life-threatening PVL-positive CA-MRSA USA300 clone infection, including sepsis, SPE, and skin and soft tissue infections with iliofemoral deep venous thrombosis.

Methicillin-resistant Staphylococcus aureus: an overview of basic and clinical research

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most successful modern pathogens. The same organism that lives as a commensal and is transmitted in both health-care and community settings is also a leading cause of bacteraemia, endocarditis, skin and soft tissue infections, bone and joint infections and hospital-acquired infections. Genetically diverse, the epidemiology of MRSA is primarily characterized by the serial emergence of epidemic strains. Although its incidence has recently declined in some regions, MRSA still poses a formidable clinical threat, with persistently high morbidity and mortality. Successful treatment remains challenging and requires the evaluation of both novel antimicrobials and adjunctive aspects of care, such as infectious disease consultation, echocardiography and source control. In this Review, we provide an overview of basic and clinical MRSA research and summarize the expansive body of literature on the epidemiology, transmission, genetic diversity, evolution, surveillance and treatment of MRSA.

Infection Risk Reduction Program on Pathogens in High School and Collegiate Athletic Training Rooms

Background:

Athletic training rooms have a high prevalence of bacteria, including multidrug-resistant organisms, increasing the risk for both local and systematic infections in athletes. There are limited data outlining formal protocols or standardized programs to reduce bacterial and viral burden in training rooms as a means of decreasing infection rate at the collegiate and high school levels.

Hypothesis:

Adaptation of a hygiene protocol would lead to a reduction in bacterial and viral pathogen counts in athletic training rooms.

Study Design:

Cohort study.

Level of Evidence:

Level 3.

Methods:

Two high school and 2 collegiate athletic training rooms were studied over the course of the 2017-2018 academic year. A 3-phase protocol, including introduction of disinfectant products followed by student-athlete and athletic trainer education, was implemented at the 4 schools. Multiple surfaces in the athletic training rooms were swabbed at 4 time points throughout the investigation. Bacterial and viral burden from swabs were analyzed for overall bacterial aerobic plate count (APC), bacterial adenosine triphosphate activity, influenza viral load, and multidrug-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE).

Results:

Overall bacterial load, as measured by APC, was reduced by 94.7% (95% CI, 72.6-99.0; P = 0.003) over the course of the investigation after protocol implementation. MRSA and VRE were found on 24% of surfaces prior to intervention and were reduced to 0% by the end of the study. Influenza was initially detected on 25% of surfaces, with no detection after intervention. No cases of athletic training room–acquired infections were reported during the study period.

Conclusion:

A uniform infection control protocol was effective in reducing bacterial and viral burden, including multidrug-resistant organisms, when implemented in the athletic training rooms of 2 high schools and 2 colleges.

Clinical Relevance:

A standardized infection control protocol can be utilized in athletic training rooms to reduce bacterial and viral burden.

Prevalence of Staphylococcus aureus carriage and pattern of antibiotic resistance, including methicillin resistance, among contact sport athletes in Italy

Background and purpose: Athletes participating in contact or collision sports have a great chance of acquiring Staphylococcus aureus infections. The risk factors for colonization and infections include frequent antibiotic use, close contact situations, skin trauma, sharing of sports equipment, and poor hygiene. Therefore, our specific goals were to determine (1) prevalence of S. aureus among different types of contact sport athletes which were barely studied in the European region, (2) antimicrobial resistance of S. aureus isolates, and (3) association of carriage with particular risk factors of spor t practices.

Patients and methods: A cross-sectional study was conducted among contact or collision sport athletes in Italy. A questionnaire was used to gather information about sociodemographic characteristics, specific sport activities, and participants’ health conditions. Swabs were collected from the nares, oropharynx, and fingers and tested for S. aureus isolation and antimicrobial susceptibility.

Results:S. aureus was carried by 42% of 238 enrolled athletes. Colonization was associated with number of weekly training days, sharing of sports equipment, not taking a shower immediately after training, and a previous history of pharyngitis or sinusitis and skin manifestations. Isolates were resistant to clindamycin (24.8%) and erythromycin (15.8%). Of all athletes, 1.3% carried methicillin-resistant S. aureus (MRSA); MRSA were 3% of all S. aureus isolates. No strains were resistant to sulfamethoxazole/trimethoprim.

Conclusion: Our results have shown a high prevalence of S. aureus carriage and a relevant resistance to antimicrobials used for the treatment of S. aureus infections. Prevention efforts aimed at reducing S. aureus colonization, and thus potentially reducing infections, should be improved.

Community-associated Methicillin-Resistant Staphylococcus aureus Infection Rates and Management among Student-Athletes

PURPOSE

Although community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have reduced among inpatient populations, the incidence in athletics continues to range greatly dependent on the sport. Over the 2015 to 2016 and 2016 to 2017 school years, we assessed the annual CA-MRSA incidence, sport risk, referral practices, and management protocols or interventions among high school and intercollegiate athletics.

METHODS

This study targeted high school and intercollegiate athletic programs across the United States. For the 2015 to 2016 study, 269 athletic trainers completed a one-time questionnaire. In the 2016 to 2017 study, 217 athletic trainers reported data bimonthly during the academic year. Each questionnaire targeted demographic information, physician-confirmed CA-MRSA infection occurrence, and management of CA-MRSA infections and bacterial skin lesions.

RESULTS

The CA-MRSA infection incidence was 26.8 per 10,000 athletes (95% confidence interval [CI], 24-30) in 2015-2016 and 20.3 per 10,000 athletes (95% CI, 18-23) in 2016-2017. The CA-MRSA infection incidence was high in wrestling and football compared to the general student-athlete population. During the 2015 to 2016 study, the wrestling incidence rate was 248.3 per 10,000 (95% CI, 204-302); the football incidence rate was 71.0 per 10,000 (95% CI, 60-85). In the 2016 to 2017 study, the wrestling incidence rate was 100.0 per 10,000 (95% CI, 66-151); the football incidence rate was 81.8 per 10,000 (95% CI, 68-99). At least 23% of respondents denoted at least one physician-confirmed CA-MRSA infection within their populations (2015-2016, 39%, n = 105; 2016-2017, 23.5%, n = 51). In the 2015 to 2016 survey, respondents indicated that athlete education and environmental decontamination were the most used management steps (51.8%, n = 582).

CONCLUSIONS

Despite increased awareness of CA-MRSA, more educational efforts focusing on best practices and education are needed, especially with athletes and the medical community involved in their care.

A Distinct Geographic Variant of sasX in Methicillin-Resistant Staphylococcus aureus ST239 and ST368 Lineage from South India

Staphylococcal surface protein sasX is a colonization mediating virulence factor in ST239 methicillin-resistant Staphylococcus aureus (MRSA) strains, which potentially contribute to its successful establishment. We aimed to study the presence and dissemination of sasX in clinical MRSA isolates and among MRSA carriers. A total of 450 nonduplicate clinical MRSA isolates recovered from blood cultures between 2013 and 2017 were included in this study. In addition, 93 nasal swabs were collected from patients receiving hemodialysis, after obtaining consent and screening for MRSA colonization. sasX polymerase chain reaction and sequencing were carried out for all isolates. Multilocus sequence typing was performed for all sasX-positive isolates. Of the tested clinical MRSA isolates, 11% (n = 48) were positive for sasX gene. Among hemodialysis patients, 26% (n = 24) were characterized as MRSA carriers. However, all MRSA strains isolated from nasal swab were negative for sasX gene. Overall, we observed 10% (11% in clinical MRSA isolates and 0% in MRSA carriers) of sasX-positive MRSA in this study. ST239 and ST368 were the predominant sasX carrying MRSA lineages. The majority of sasX carrying MRSA strains were characterized as Staphylococcus epidermidis surface protein I (sesI; 71%), a sasX homolog native to S. epidermidis. This study highlights the dissemination of sasX/sesI to ST368 (CC8), ST3324 (CC8), ST772 (CC1), and ST22 (CC22). The presence of S. epidermidis-specific invasive factor sesI in clinical MRSA strains provides evidence for horizontal transfer between these closely related species.

Conjugative Transfer of a Novel Staphylococcal Plasmid Encoding the Biocide Resistance Gene, qacA

Staphylococcus aureus is the leading cause of skin and soft tissue infections (SSTI). Some S. aureus strains harbor plasmids that carry genes that affect resistance to biocides. Among these genes, qacA encodes the QacA Multidrug Efflux Pump that imparts decreased susceptibility to chlorhexidine, a biocide used ubiquitously in healthcare facilities. Furthermore, chlorhexidine has been considered as a S. aureus decolonization strategy in community settings. We previously conducted a chlorhexidine-based SSTI prevention trial among Ft. Benning Army trainees. Analysis of a clinical isolate (C02) from that trial identified a novel qacA-positive plasmid, pC02. Prior characterization of qacA-containing plasmids is limited and conjugative transfer of those plasmids has not been demonstrated. Given the implications of increased biocide resistance, herein we characterized pC02. In silico analysis identified genes typically associated with conjugative plasmids. Moreover, pC02 was efficiently transferred to numerous S. aureus strains and to Staphylococcus epidermidis. We screened additional qacA-positive S. aureus clinical isolates and pC02 was present in 27% of those strains; other unique qacA-harboring plasmids were also identified. Ten strains were subjected to whole genome sequencing. Sequence analysis combined with plasmid screening studies suggest that qacA-containing strains are transmitted among military personnel at Ft. Benning and that strains carrying qacA are associated with SSTIs within this population. The identification of a novel mechanism of qacA conjugative transfer among Staphylococcal strains suggests a possible future increase in the prevalence of antiseptic tolerant bacterial strains, and an increase in the rate of infections in settings where these agents are commonly used.

Infectious Disease in Contact Sports

CONTEXT:

Infections are common in contact sports. This review aims to describe the epidemiology, presenting signs and symptoms, treatment guidelines, and regulations for several common infections seen in contact sport athletes. The conditions discussed include bacterial skin infections, herpes simplex virus, molluscum contagiosum, common warts, tinea, scabies, head lice, conjunctivitis, human immunodeficiency virus, hepatitis C virus, and vaccine-preventable illnesses.

EVIDENCE ACQUISITION:

Searches were performed across PubMed and MEDLINE research databases. In addition, general internet search engine results and reviews of reference lists of relevant papers were used to identify additional sources of evidence.

STUDY DESIGN:

Clinical review.

LEVEL OF EVIDENCE:

Level 4.

RESULTS:

The most common infections seen in contact sport athletes include bacterial skin infections, herpes simplex virus, molluscum contagiosum, common warts, tinea, scabies, head lice, conjunctivitis, and vaccine-preventable illnesses. Other infections, including human immunodeficiency virus and hepatitis C, are uncommon but potentially life threatening.

CONCLUSION:

Infections are common in contact sport athletes. The provider who cares for these athletes should be aware of the most common infections and their appropriate management. Early diagnosis and appropriate clinical management are important for treating the infected athlete, minimizing risk of transmission, minimizing time lost from competition, and preventing large outbreaks.

Polyhexamethylene Biguanide and Nadifloxacin Self-Assembled Nanoparticles: Antimicrobial Effects against Intracellular Methicillin-Resistant Staphylococcus aureus

The treatment of skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge, partly due to localization of the bacteria inside the host’s cells, where antimicrobial penetration and efficacy is limited. We formulated the cationic polymer polyhexamethylene biguanide (PHMB) with the topical antibiotic nadifloxacin and tested the activities against intracellular MRSA in infected keratinocytes. The PHMB/nadifloxacin nanoparticles displayed a size of 291.3 ± 89.6 nm, polydispersity index of 0.35 ± 0.04, zeta potential of +20.2 ± 4.8 mV, and drug encapsulation efficiency of 58.25 ± 3.4%. The nanoparticles killed intracellular MRSA, and relative to free polymer or drugs used separately or together, the nanoparticles displayed reduced toxicity and improved host cell recovery. Together, these findings show that PHMB/nadifloxacin nanoparticles are effective against intracellular bacteria and could be further developed for the treatment of skin and soft tissue infections.