Methicillin-resistant Staphylococcus aureus (MRSA) in the Athlete

Unilateral lymphadenitis caused by community-associated methicillin-resistant Staphylococcus aureus ST834 strain

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a global concern, primarily as a cause of skin and soft tissue infections, particularly in young people. Here, we describe a case of unilateral multiple lymphadenitis caused by the CA-MRSA sequence type (ST) 834 strain. A previously healthy 15-year-old girl was referred to our hospital with fever and swollen lymph nodes in the right axillary, cubital, and groin regions. Imaging examinations revealed enlargement of the lymph nodes in these areas but no swelling in any other lymph nodes. The patient had self-destructive lymph nodes in her groin. MRSA was detected in all swollen lymph node samples. Antimicrobial susceptibility tests showed that MRSA was susceptible to clindamycin and levofloxacin, leading to the suspicion of CA-MRSA. Genetic analysis revealed that all strains were ST834 and carried the staphylococcal cassette chromosome mec IV and the toxic shock syndrome toxin-1 gene but not the Panton-Valentine leukocidin gene. The patient was treated with linezolid followed by oral clindamycin. This was a rare case of unilateral multiple lymphadenitis caused by ST834 CA-MRSA. Although ST834 strains are rarely reported, lymphadenitis has been frequently reported and is considered more likely to cause lymphadenitis than other CA-MRSA strains.

Time Out of Play Due to Illness in Major and Minor League Baseball

OBJECTIVE

To generate a summative report on the most commonly diagnosed illnesses in Major League Baseball (MLB) and Minor League Baseball (MiLB) athletes with specific attention to their impact based on time out of play.

DESIGN

Retrospective analysis.

SETTING

Injury and illness data from the MLB Health and Injury Tracking System.

PARTICIPANTS

All MLB and MiLB athletes active between 2011 and 2016.

ASSESSMENT OF RISK FACTORS

Illnesses were defined as atraumatic medical diagnoses that occurred during the MLB or MiLB season and resulted in at least 1 day out of play.

MAIN OUTCOME MEASURES

Incidence of illness diagnoses and resulting time out play.

RESULTS

Eight thousand eight hundred thirty-four illnesses were reported, representing 14.7% of all diagnoses resulting in time out of play. Total days missed (DM) due to illness were 39 614, with a mean of 4.6 (SD 9.9 days) and median 2 DM per diagnosis. The annual incidence of illness per season was 20.3 per 100 athletes. The most common diagnosis was nonspecific viral illness (15.3%), followed by gastroenteritis (13.6%), other gastrointestinal illness (8.3%), influenza (7.0%), and upper respiratory infection (6.2%). Appendicitis (15.2%) and Epstein-Barr virus/cytomegalovirus (9.1%) were the most common season-ending diagnoses.

CONCLUSIONS

Illnesses represent a significant cause of time out of play in MLB and MiLB. Prevention efforts should focus on limiting the spread of communicable viral, respiratory, and gastrointestinal disease among players, as the majority of diagnoses fell into these categories. This work may be used to guide future research into illness treatment and prevention in professional baseball.

Methicillin-Resistant Staphylococcus aureus: Risk for General Infection and Endocarditis Among Athletes

The first studies on Staphylococcus aureus (SA) infections in athletes were conducted in the 1980s, and examined athletes that perform in close physical contact, with particular attention to damaged or infected skin. Recent studies have used molecular epidemiology to shed light on the transmission of SA in professional athletes. These studies have shown that contact between athletes is prolonged and constant, and that these factors influence the appearance of infections caused by SA. These results support the need to use sanitary measures designed to prevent the appearance of SA infections. The factors triggering the establishment of SA within professional sports groups are the nasal colonization of SA, contact between athletes and sweating. Hence, there is a need to use the most modern molecular typing methods to evaluate the appearance of cutaneous SA disease. This review aims to summarize both the current SA infections known in athletes and the diagnostic methods employed for recognition, pointing to possible preventive strategies and the factors that can act as a springboard for the appearance of SA and subsequent transmission between athletes.

Infectious Diseases Associated With Organized Sports and Outbreak Control

Participation in organized sports has a variety of health benefits but also has the potential to expose the athlete to a variety of infectious diseases, some of which may produce outbreaks. Major risk factors for infection include skin-to-skin contact with athletes who have active skin infections, environmental exposures and physical trauma, and sharing of equipment and contact with contaminated fomites. Close contact that is intrinsic to team sports and psychosocial factors associated with adolescence are additional risks. Minimizing risk requires leadership by the organized sports community (including the athlete's primary care provider) and depends on outlining key hygiene behaviors, recognition, diagnosis, and treatment of common sports-related infections, and the implementation of preventive interventions.

Comparative Prevalence of Immune Evasion Complex Genes Associated with β-Hemolysin Converting Bacteriophages in MRSA ST5 Isolates from Swine, Swine Facilities, Humans with Swine Contact, and Humans with No Swine Contact

Livestock associated methicillin-resistant Staphylococcus aureus (LA-MRSA) draws concern from the public health community because in some countries these organisms may represent the largest reservoir of MRSA outside hospital settings. Recent studies indicate LA-MRSA strains from swine are more genetically diverse than the first reported sequence type ST398. In the US, a diverse population of LA-MRSA is found including organisms of the ST398, ST9, and ST5 lineages. Occurrence of ST5 MRSA in swine is of particular concern since ST5 is among the most prevalent lineages causing clinical infections in humans. The prominence of ST5 in clinical disease is believed to result from acquisition of bacteriophages containing virulence or host-adapted genes including the immune-evasion cluster (IEC) genes carried by β-hemolysin converting bacteriophages, whose absence in LA-MRSA ST398 is thought to contribute to reduced rates of human infection and transmission associated with this lineage. The goal of this study was to investigate the prevalence of IEC genes associated with β-hemolysin converting bacteriophages in MRSA ST5 isolates obtained from agricultural sources, including swine, swine facilities, and humans with short- or long-term swine exposure. To gain a broader perspective, the prevalence of these genes in LA-MRSA ST5 strains was compared to the prevalence in clinical MRSA ST5 strains from humans with no known exposure to swine. IEC genes were not present in any of the tested MRSA ST5 strains from agricultural sources and the β-hemolysin gene was intact in these strains, indicating the bacteriophage’s absence. In contrast, the prevalence of the β-hemolysin converting bacteriophage in MRSA ST5 strains from humans with no exposure to swine was 90.4%. The absence of β-hemolysin converting bacteriophage in LA-MRSA ST5 isolates is consistent with previous reports evaluating ST398 strains and provides genetic evidence indicating LA-MRSA ST5 isolates may harbor a reduced capacity to cause severe disease in immunocompetent humans.

Staphylococcus aureus and community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in and around therapeutic whirlpools in college athletic training rooms

CONTEXT

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has become a leading cause of skin and soft tissue infection in the nonhospitalized community. Care of the athletes in athletic training rooms is specifically designed with equipment tailored to the health care needs of the athletes, yet recent studies indicate that CA-MRSA is still prevalent in athletic facilities and that cleaning methods may not be optimal.

OBJECTIVE

To investigate the prevalence of Staphylococcus aureus and CA-MRSA in and around whirlpools in the athletic training room.

DESIGN

Cross-sectional study.

SETTING

National Collegiate Athletic Association Division I university.

PATIENTS OR OTHER PARTICIPANTS

Student-athletes (n = 109) consisting of 46 men (42%) and 63 women (58%) representing 6 sports.

MAIN OUTCOME MEASURE(S)

Presence of MRSA and Staphylococcus aureus in and around the whirlpool structures relative to sport and number of athletes using the whirlpools.

RESULTS

We identified Staphylococcus aureus in 22% (n = 52/240) of the samples and MRSA in 0.8% (n = 2/240). A statistically significant difference existed between the number of athletes using the whirlpool and the presence of Staphylococcus aureus in and around the whirlpools (F(2,238) = 2.445, P = .007). However, Staphylococcus aureus was identified regardless of whether multiple athletes used a whirlpool or no athletes used a whirlpool. We did not identify a relationship between the number of athletes who used a whirlpool and Staphylococcus aureus or MRSA density (P = .134).

CONCLUSIONS

Staphylococcus aureus and MRSA were identified in and around the whirlpools. Transmission of the bacteria can be reduced by following the cleaning and disinfecting protocols recommended by the Centers for Disease Control and Prevention. Athletic trainers should use disinfectants registered by the Environmental Protection Agency to sanitize all whirlpools between uses.

Salvage of contaminated osteochondral allografts: the effects of chlorhexidine on human articular chondrocyte viability

BACKGROUND

Because chondrocyte viability is imperative for successful osteochondral allograft transplantation, sterilization techniques must provide antimicrobial effects with minimal cartilage toxicity. Chlorhexidine gluconate (CHG) is an effective disinfectant; however, its use with human articular cartilage requires further investigation.

PURPOSE

To determine the maximal chlorhexidine concentration that does not affect chondrocyte viability in allografts and to determine whether this concentration effectively sterilizes contaminated osteoarticular grafts.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteochondral plugs were subjected to pulse lavage with 1-L solutions of 0.002%, 0.01%, 0.05%, and 0.25% CHG and cultured for 0, 1, 2, and 7 days in media of 10% fetal bovine serum and antibiotics. Chondrocyte viability was determined via LIVE/DEAD Viability Assay. Plugs were contaminated with Staphylococcus aureus and randomized to 4 treatment groups. One group was not contaminated; the 3 others were contaminated and received no treatment, saline pulse lavage, or saline pulse lavage with 0.002% CHG. Serial dilutions were plated and colony-forming units assessed.

RESULTS

The control group and the 0.002% CHG group showed similar cell viability, ranging from 67% ± 4% to 81% ± 22% (mean ± SD) at all time points. In the 0.01% CHG group, cell viability was reduced in comparison with control by 2-fold at day 2 and remained until day 7 (P < .01). The 0.05% and 0.25% CHG groups showed a 2-fold reduction in cell viability at day 1 (P < .01). At day 7, cell viability was reduced to 15% ± 18% (4-fold decrease) for the 0.05% CHG group and 10% ± 19% (6-fold decrease) for the 0.25% CHG group (P < .01). Contaminated grafts treated with 0.002% CHG demonstrated no colony-forming units.

CONCLUSION

Pulse lavage with 0.002% CHG does not cause significant cell death within 7 days after exposure, while CHG at concentrations >0.002% significantly decreases chondrocyte viability within 1 to 2 days after exposure and should therefore not be used for disinfection of osteochondral allograft. Pulse lavage does not affect chondrocyte viability but cannot be used in isolation to sterilize contaminated fragments. Overall, 0.002% CHG was shown to effectively decontaminate osteoarticular fragments.

CLINICAL RELEVANCE

This study offers a scientific protocol for sterilizing osteochondral fragments that does not adversely affect cartilage viability.

Methicillin-resistant staphylococci: implications for our food supply?

Food-borne intoxication, caused by heat-stable enterotoxins produced by Staphylococcus aureus, causes over 240,000 cases of food-borne illness in the United States annually. Other staphylococci commonly associated with animals may also produce these enterotoxins. Foods may be contaminated by infected food handlers during slaughter and processing of livestock or by cross-contamination during food preparation. S. aureus also causes a variety of mild to severe skin and soft tissue infections in humans and other animals. Antibiotic resistance is common in staphylococci. Hospital-associated (HA) S. aureus are resistant to numerous antibiotics, with methicillin-resistant S. aureus (MRSA) presenting significant challenges in health care facilities for over 40 years. During the mid-1990s new human MRSA strains developed outside of hospitals and were termed community-associated (CA). A few years later, MRSA was isolated from horses and methicillin resistance was detected in Staphylococcus intermedius/pseudintermedius from dogs and cats. In 2003, a livestock-associated (LA) MRSA strain was first detected in swine. These methicillin-resistant staphylococci pose additional food safety and occupational health concerns. MRSA has been detected in a small percentage of retail meat and raw milk samples indicating a potential risk for food-borne transmission of MRSA. Persons working with animals or handling meat products may be at increased risk for antibiotic-resistant infections. This review discusses the scope of the problem of methicillin-resistant staphylococci and some strategies for control of these bacteria and prevention of illness.

Certified athletic trainers' knowledge of methicillin-resistant Staphylococcus aureus and common disinfectants

CONTEXT

Methicillin-resistant Staphylococcus aureus (MRSA) infections are increasingly common in athletic settings. The MRSA knowledge and infection-control practices of certified athletic trainers (ATs) and the cleanliness of the athletic training room are important factors in preventing MRSA infections.

OBJECTIVE

To assess knowledge of MRSA and the use of common disinfectants among ATs and to explore their infection-control practices.

DESIGN

Cross-sectional study.

SETTING

High school and collegiate athletic training rooms.

PATIENTS OR OTHER PARTICIPANTS

A total of 163 ATs from National Collegiate Athletic Association Divisions I, II, and III and high schools, representing all 10 National Athletic Trainers' Association districts.

MAIN OUTCOME MEASURE(S)

Frequencies, analyses of variance, and χ(2) tests were used to assess current practices and opinions and relationships between factors.

RESULTS

Methicillin-resistant Staphylococcus aureus was perceived as a national problem by 92% of respondents; 57% perceived MRSA as a problem in their practice setting. Most respondents had treated general infections (88%), staphylococcal infections (75%), and MRSA infections (57%). Male sex was associated with treating all 3 types of infections (χ(2) test, P < .05). Noncurriculum education was associated with a lack of recognition of environmental issues as risk factors and with the use of isopropyl alcohol for disinfection (χ(2) test, P < .05). For example, 10% of respondents did not recognize that contaminated whirlpools can be a source of MRSA infection. Respondents also incorrectly identified effective cleaning solutions. Thirty percent of respondents cleaned their hands frequently or sometimes before treating each athlete and 35% cleaned their hands sometimes, occasionally, or never after seeing each athlete.

CONCLUSIONS

The majority of ATs were informed about MRSA and made correct disinfection choices. However, improvements are still needed, and not all ATs were using proper disinfection practices.

Increased prevalence of methicillin-resistant Staphylococcus aureus nasal colonization in household contacts of children with community acquired disease

Background

To measure Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization prevalence in household contacts of children with current community associated (CA)-MRSA infections (study group) in comparison with a group of household contacts of children without suspected Staphylococcus aureus infection (a control group).

Methods

This is a cross sectional study. Cultures of the anterior nares were taken. Relatedness of isolated strains was tested using pulse field gel electrophoresis (PFGE).

Results

The prevalence of MRSA colonization in the study group was significantly higher than in the control group (18/77 (23%) vs 3/77 (3.9%); p ≤ 0.001). The prevalence of SA colonization was 28/77 (36%) in the study group and 16/77 (21%) in the control group (p = 0.032). The prevalence of SA nasal colonization among patients was 6/24 (25%); one with methicillin-susceptible S. aureus (MSSA) and 5 with MRSA. In the study (patient) group, 14/24 (58%) families had at least one household member who was colonized with MRSA compared to 2/29 (6.9%) in the control group (p = 0.001). Of 69 total isolates tested by PFGE, 40 (58%) were related to USA300. Panton-Valetine leukocidin (PVL) genes were detected in 30/52 (58%) tested isolates. Among the families with ≥1 contact colonized with MRSA, similar PFGE profiles were found between the index patient and a contact in 10/14 families.

Conclusions

Prevalence of asymptomatic nasal carriage of MRSA is higher among household contacts of patients with CA-MRSA disease than control group. Decolonizing such carriers may help prevent recurrent CA-MRSA infections.

Community-acquired methicillin-resistant Staphylococcus aureus: community transmission, pathogenesis, and drug resistance

Methicillin-resistant Staphylococcus aureus (MRSA) is able to persist not only in hospitals (with a high level of antimicrobial agent use) but also in the community (with a low level of antimicrobial agent use). The former is called hospital-acquired MRSA (HA-MRSA) and the latter community-acquired MRSA (CA-MRSA). It is believed MRSA clones are generated from S. aureus through insertion of the staphylococcal cassette chromosome mec (SCCmec), and outbreaks occur as they spread. Several worldwide and regional clones have been identified, and their epidemiological, clinical, and genetic characteristics have been described. CA-MRSA is likely able to survive in the community because of suitable SCCmec types (type IV or V), a clone-specific colonization/infection nature, toxin profiles (including Pantone-Valentine leucocidin, PVL), and narrow drug resistance patterns. CA-MRSA infections are generally seen in healthy children or young athletes, with unexpected cases of diseases, and also in elderly inpatients, occasionally surprising clinicians used to HA-MRSA infections. CA-MRSA spreads within families and close-contact groups or even through public transport, demonstrating transmission cores. Re-infection (including multifocal infection) frequently occurs, if the cores are not sought out and properly eradicated. Recently, attention has been given to CA-MRSA (USA300), which originated in the US, and is growing as HA-MRSA and also as a worldwide clone. CA-MRSA infection in influenza season has increasingly been noted as well. MRSA is also found in farm and companion animals, and has occasionally transferred to humans. As such, the epidemiological, clinical, and genetic behavior of CA-MRSA, a growing threat, is focused on in this study.