Genomic Characterization of USA300 Methicillin-Resistant Staphylococcus aureus (MRSA) to Evaluate Intraclass Transmission and Recurrence of Skin and Soft Tissue Infection (SSTI) Among High-Risk Military Trainees

BACKGROUND

Military trainees are at increased risk for methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infection (SSTI). Whole genome sequencing (WGS) can refine our understanding of MRSA transmission and microevolution in congregate settings.

METHODS

We conducted a prospective case-control study of SSTI among US Army infantry trainees at Fort Benning, Georgia, from July 2012 to December 2014. We identified clusters of USA300 MRSA SSTI within select training classes and performed WGS on clinical isolates. We then linked genomic, phylogenetic, epidemiologic, and clinical data in order to evaluate intra- and interclass disease transmission. Furthermore, among cases of recurrent MRSA SSTI, we evaluated the intrahost relatedness of infecting strains.

RESULTS

Nine training classes with ≥5 cases of USA300 MRSA SSTI were selected. Eighty USA300 MRSA clinical isolates from 74 trainees, 6 (8.1%) of whom had recurrent infection, were subjected to WGS. We identified 2719 single nucleotide variants (SNVs). The overall median (range) SNV difference between isolates was 173 (1-339). Intraclass median SNV differences ranged from 23 to 245. Two phylogenetic clusters were suggestive of interclass MRSA transmission. One of these clusters stemmed from 2 classes that were separated by a 13-month period but housed in the same barracks. Among trainees with recurrent MRSA SSTI, the intrahost median SNV difference was 7.5 (1-48).

CONCLUSIONS

Application of WGS revealed intra- and interclass transmission of MRSA among military trainees. An interclass cluster between 2 noncontemporaneous classes suggests a long-term reservoir for MRSA in this setting.

Strategies for Prevention of Methicillin Resistant Staphylococcus aureus (MRSA) Infections and Decolonization

Methicillin resistant Staphylococcus aureus (MRSA) invasive infections can be severe in the pediatric population with high morbidity and mortality. MRSA colonization can predispose to recurrent skin and soft tissue infections and invasive MRSA disease and is a frequent challenge faced by clinicians. This article reviews the importance of MRSA as a pathogen, MRSA colonization and various MRSA decolonization strategies.

[Cluster outbreak of MRSA in the community; recognition and approach]

BACKGROUND

Community-acquired infection with methicillin-resistant Staphylococcus aureus (CA-MRSA) mainly affects healthy young people, without health-care related risk factors for MRSA. Patients often present with skin and soft-tissue infections.

CASE DESCRIPTION

An 18-year-old woman presented at the casualty department with recurrent purulent skin infections. She proved to be MRSA-positive. Within 6 months, 2 people around her also developed an MRSA infection. Culture showed CA-MRSA, with an identical strain (spa type: t008). Additional screening within her immediate circle identified 4 carriers, 2 of whom had corresponding skin infections.

CONCLUSION

Cluster outbreaks of CA-MRSA require a coordinated approach from both the treating physician and the public health services. The choice of additional investigation among the circle of contacts was the determining factor in breaking the cycle of transmission and reinfection within this cluster.

A data-driven mathematical model of CA-MRSA transmission among age groups: evaluating the effect of control interventions

Community associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has become a major cause of skin and soft tissue infections (SSTIs) in the US. We developed an age-structured compartmental model to study the spread of CA-MRSA at the population level and assess the effect of control intervention strategies. We used Monte-Carlo Markov Chain (MCMC) techniques to parameterize our model using monthly time series data on SSTIs incidence in children (≤ 19 years) during January 2004 -December 2006 in Maricopa County, Arizona. Our model-based forecast for the period January 2007-December 2008 also provided a good fit to data. We also carried out an uncertainty and sensitivity analysis on the control reproduction number, Rc which we estimated at 1.3 (95% CI [1.2,1.4]) based on the model fit to data. Using our calibrated model, we evaluated the effect of typical intervention strategies namely reducing the contact rate of infected individuals owing to awareness of infection and decolonization strategies targeting symptomatic infected individuals on both [Formula: see text] and the long-term disease dynamics. We also evaluated the impact of hypothetical decolonization strategies targeting asymptomatic colonized individuals. We found that strategies focused on infected individuals were not capable of achieving disease control when implemented alone or in combination. In contrast, our results suggest that decolonization strategies targeting the pediatric population colonized with CA-MRSA have the potential of achieving disease elimination.

Use of copper alloy for preventing transmission of methicillin-resistant Staphylococcus aureus contamination in the dermatology ward

Metallic copper has been shown significantly to reduce methicillin-resistant Staphylococcus aureus (MRSA) contamination of the ambient surroundings of the beds of MRSA-carrying patients in dermatology wards. The aim of this study was to determine whether a bed sheet made of copper-coated film will reduce the spread of MRSA contamination in the environment of a heavily-colonized patient. The bacterial count was highest on the bed sheet. MRSA cell counts on the surface of the non-film-coated control sheet were high (6,600-11,000 colony forming units (cfu)), but those on the copper film were considerably lower (20-130 cfu). Use of metallic copper on the bed sheets of patients who are likely to be a source of MRSA contamination may help to prevent the spread of MRSA contamination in hospital wards.

Induction of the staphylococcal proteolytic cascade by antimicrobial fatty acids in community acquired methicillin resistant Staphylococcus aureus

Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA), and the USA300 strain of CA-MRSA in particular, are known for their rapid community transmission, and propensity to cause aggressive skin and soft tissue infections. To assess factors that contribute to these hallmark traits of CA-MRSA, we evaluated how growth of USA300 and production of secreted virulence factors was influenced on exposure to physiologic levels of unsaturated free fatty acids that would be encountered on the skin or anterior nares, which represent the first sites of contact with healthy human hosts. There was a sharp threshold between sub-inhibitory and inhibitory concentrations, such that 100 µM sapienic acid (C16∶1) and linoleic acid (C18∶1) were sufficient to prevent growth after 24 h incubation, while 25 µM allowed unrestricted growth, and 50 µM caused an approximate 10–12 h lag, followed by unimpeded exponential growth. Conversely, saturated palmitic or stearic acids did not affect growth at 100 µM. Although growth was not affected by 25 µM sapienic or linoleic acid, these and other unsaturated C16 and C18 fatty acids, but not their saturated counterparts, promoted robust production of secreted proteases comprising the Staphylococcal proteolytic cascade. This trait was also manifested to varying degrees in other CA-MRSA, and in genetically diverse methicillin susceptible S. aureus strains. Therefore, induction of the Staphylococcal proteolytic cascade by unsaturated fatty acids is another feature that should now be evaluated as a potential contributing factor in the aggressive nature of skin and soft tissue infections caused by USA300, and as a general virulence mechanism of S. aureus.

Risk factors for community-associated Staphylococcus aureus skin infection in children of Maui

The prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection, and Staphylococcus aureus (S. aureus) infection overall, has dramatically increased in the past 10 years. Children and Native Hawaiians and Pacific Islanders (NHPI) are disproportionately affected by CA-MRSA infection. The purpose of this case-control study was to identify risk factors for CA-S. aureus skin infections in children of Maui, Hawai'i, as a foundation for reducing the transmission of these infections. Survey data were obtained from patients in pediatric clinician offices over an 8-month period. NHPI participants were well-represented as 58% of cases and 54% of controls. Chi-square analysis and logistic regression were used to identify risk factors. Significant risk factors predictive of infection among all participants were (a) skin abrasions or wounds, (b) household contact, and (c) overweight or obesity. Risk factors predictive of infection among NHPI were (a) skin abrasions or wounds, (b) antibiotic use within 6 months, (c) overweight or obesity, and (d) a history of eczema or other skin disorder. The role of overweight or obesity in S. aureus skin infections among NHPI has not been identified in previous research and indicates a focus for additional education. Further research is needed to better understand the role of eczema, antibiotic use, overweight and obesity, and socio-cultural factors in these infections.

Staphylococcus aureus colonization among household contacts of patients with skin infections: risk factors, strain discordance, and complex ecology

BACKGROUND

The USA300 methicillin resistant Staphylococcus aureus (MRSA) genetic background has rapidly emerged as the predominant cause of community-associated S. aureus infections in the U.S. However, epidemiologic characteristics of S. aureus household transmission are poorly understood.

METHODS

We performed a cross-sectional study of adults and children with S. aureus skin infections and their household contacts in Los Angeles and Chicago. Subjects were surveyed for S. aureus colonization of the nares, oropharynx, and inguinal region and risk factors for S. aureus disease. All isolates underwent genetic typing.

RESULTS

We enrolled 1162 persons (350 index patients and 812 household members). The most common infection isolate characteristic was ST8/SCCmec IV, PVL+ MRSA (USA300) (53%). S. aureus colonized 40% (137/350) of index patients and 50% (405/812) of household contacts. A nares-only survey would have missed 48% of S. aureus and 51% of MRSA colonized persons. Sixty-five percent of households had >1 S. aureus genetic background identified and 26% of MRSA isolates in household contacts were discordant with the index patients' infecting MRSA strain type. Factors independently associated (P < .05) with the index strain type colonizing household contacts were recent skin infection, recent cephalexin use, and USA300 genetic background.

CONCLUSIONS

In our study population, USA300 MRSA appeared more transmissible among household members compared with other S. aureus genetic backgrounds. Strain distribution was complex; >1 S. aureus genetic background was present in many households. S. aureus decolonization strategies may need to address extra-nasal colonization and the consequences of eradicating S. aureus genetic backgrounds infrequently associated with infection.

Methicillin-resistant Staphylococcus aureus skin infections from an elephant calf--San Diego, California, 2008

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a major cause of human skin and soft tissue infections in the United States. MRSA colonization and infection also have been observed in turtles, bats, seals, sheep, rabbits, rodents, cats, dogs, pigs, birds, horses, and cattle, and MRSA infections with an epidemiologic link to animal contact have been reported in veterinary personnel, pet owners, and farm animal workers. On January 29, 2008, the County of San Diego Health and Human Services Agency was notified of skin pustules on an African elephant (Loxodonta africana) calf and three of its caretakers at a zoo in San Diego County. After each of these infections (including the calf's infection) was laboratory confirmed as MRSA, an outbreak investigation and response was initiated by the zoo and the agency. This report summarizes the results of that investigation, which identified two additional confirmed MRSA infections, 15 suspected MRSA infections, and three MRSA-colonized persons (all among calf caretakers), and concluded that infection of the elephant calf likely came from a colonized caretaker. This is the first reported case of MRSA in an elephant and of suspected MRSA transmission from an animal to human caretakers at a zoo. Recommendations for preventing MRSA transmission in zoo settings include 1) training employees about their risks for infection and the recommended work practices to reduce them; 2) performing proper hand hygiene before and after animal contact; 3) using personal protective equipment (PPE) when working with ill or infected animals, especially during wound treatment; and 4) cleaning and disinfecting contaminated equipment and surfaces.

[Incidence of methicillin-resistant Staphylococcus aureus in community-onset paediatric skin infections: a retrospective study 2000-2005]

BACKGROUND

A dramatic increase in the incidence of methicillin-resistant Staphylococcus aureus (MRSA) in community-onset skin infections has been reported over the last 10 years in the USA. The emergence of MRSA has been recently described in France. The aims of this study were to assess the incidence of MRSA in community-onset skin infections and to analyse the characteristics of MRSA skin infections in a French paediatric population.

PATIENTS AND METHODS

This is a retrospective study covering the period January 2000 to December 2005. Patients aged under 15 years with S. aureus isolated from skin and a clinical diagnosis of skin infection were included.

RESULTS

One hundred and thirty-four children were included with a median age of 3.4 years. There were no significant differences in MRSA prevalence between the different years of the study. The overall prevalence of MRSA was 8.2% (n=11/134). None of the isolated strains presented an antimicrobial susceptibility profile suggestive of the ST80-type community-acquired MRSA described in France. Three MRSA strains were isolated from serious superantigen-mediated skin infections. The antimicrobial susceptibility and genetic profile (tst-positive agr2 MSRA) for one strain of S. aureus militated strongly in favour of an MRSA ST5 clone skin infection.

CONCLUSION

In this study we found no evidence of epidemic spread of MRSA in community-onset childhood skin infections between 2000-2005. Nevertheless, we report three cases of serious MRSA-induced superantigen-associated skin infection. This argues in favour of the presence of virulent community MRSA clones in France.

Epidemiology of European community-associated methicillin-resistant Staphylococcus aureus clonal complex 80 type IV strains isolated in Denmark from 1993 to 2004

In Europe, community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have been caused predominantly by isolates belonging to the "European CA-MRSA" clone (sequence type 80, staphylococcal cassette chromosome mec type IV). In this study, the epidemiology of European CA-MRSA was investigated on a nationwide scale, covering the period from 1993 to 2004. Denmark has been a low-prevalence country regarding MRSA since the mid-1970s but has experienced an increase in the number of new MRSA cases in recent years. Our results show that European CA-MRSA contributed to this increase. The isolates primarily caused skin and soft tissue infections (SSTIs) in patients outside hospitals, and transmission between household members was the predominant mode of spread. Although some of the isolates were found in hospitalized patients, nosocomial transmission seemed likely in only one instance, pointing to endogenous infections as an important factor. Compared to the CA-MRSA clone most common in the United States (USA300), the European CA-MRSA clone seems less well adapted to persist in hospital environments. Patients with a recent history of travel or family relation to the Mediterranean or Middle East were highly overrepresented. The epidemiological data indicated that the European CA-MRSA isolates were introduced into Denmark on multiple occasions, paralleled by an increasing level of genetic diversity of the isolates found during the study period. European CA-MRSA has previously been described as a rather uniform clone. However, we found pronounced, diverse pulsed-field gel electrophoresis subtypes, staphylococcal protein A gene (spa) types, and susceptibility patterns.

Methicillin-resistant Staphylococcus aureus infections among healthy full-term newborns

OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged in the community, causing disease among healthy people lacking traditional risk factors for MRSA infection. This article describes an outbreak of MRSA among healthy full-term newborns.

DESIGN

Cases were identified and corresponding medical information collected. Telephone interviews were conducted with mothers of cases and surveillance cultures from mothers and newborns were performed. MRSA isolates were genotyped.

SETTING

Hospital in Chicago, Illinois, USA.

PARTICIPANTS

Newborns, their mothers and hospital healthcare workers.

INTERVENTION

Nursery infection control practices were enhanced. The MRSA-colonised healthcare workers received intranasal mupirocin.

MAIN OUTCOME

Within 4-23 days of birth, 11 newborns were identified with pustules, vesicles or blisters located on the head, groin, perineum, ears, legs, chin and trunk. All received antimicrobials and recovered without incident.

RESULTS

None of 432 peripartum women, one of 399 newborns, and two of 135 healthcare workers were nasal MRSA carriers. Available isolates from six patients, two healthcare workers, and one from an MRSA-colonised newborn were similar by pulsed-field gel electrophoresis. Other than contact with the hospital, no common exposures of MRSA transmission were identified.

CONCLUSIONS

MRSA strains that initially emerged in the community are now causing disease in healthcare settings. Providers should be aware that MRSA can cause skin infections among healthy newborns. Adherence to standard infection control practices is important to prevent transmission of MRSA in nurseries.

Cluster of Staphylococcus aureus and dengue co-infection in Singapore

INTRODUCTION

Singapore saw a resurgence of dengue infections in 2005. Concurrent bacterial co-infections in dengue is rare.

CLINICAL PICTURE

We report a cluster of serious methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia or severe soft tissue infection in 5 epidemiologically linked construction workers presenting with dengue and non-resolving fever.

TREATMENT

Surgical intervention was indicated in 4 of the 5 patients despite appropriate antistaphylococcal therapy.

OUTCOME

All but 1 patient were eventually discharged. Clonality and Panton-Valentine leucocidin genes were not demonstrated. Epidemiological investigations suggested that occupational contact dermatitis could have predisposed the patients to this opportunistic co-infection.

CONCLUSION

Clinicians need to be vigilant to unusual manifestations of dengue which may signal a concomitant aetiology.

Community-Associated Methicillin-Resistant Staphylococcus aureus Skin and Soft Tissue Infections at a Public Hospital

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have emerged among patients without health care-associated risk factors. Understanding the epidemiology of CA-MRSA is critical for developing control measures.

METHODS

At a 464-bed public hospital in Chicago and its more than 100 associated clinics, surveillance of soft tissue, abscess fluid, joint fluid, and bone cultures for S aureus was performed. We estimated rates of infection and geographic and other risks for CA-MRSA through laboratory-based surveillance and a case-control study.

RESULTS

The incidence of CA-MRSA skin and soft tissue infections increased from 24.0 cases per 100,000 people in 2000 to 164.2 cases per 100,000 people in 2005 (relative risk, 6.84 [2005 vs 2000]). Risk factors were incarceration (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.00-3.67), African American race/ethnicity (OR, 1.91; 95% CI, 1.28-2.87), and residence at a group of geographically proximate public housing complexes (OR, 2.50; 95% CI, 1.25-4.98); older age was inversely related (OR, 0.89; 95% CI, 0.82-0.96 [for each decade increase]). Of 73 strains tested, 79% were pulsed-field gel electrophoresis type USA300.

CONCLUSIONS

Clonal CA-MRSA infection has emerged among Chicago's urban poor. It has occurred in addition to, not in place of, methicillin-susceptible S aureus infection. Epidemiological analysis suggests that control measures could focus initially on core groups that have contributed disproportionately to risk, although CA-MRSA becomes endemic as it disseminates within communities.

Community MRSA

Additional to epidemic methicillin resistant Staphylococcus aureus (haMRSA) which had been disseminated in and between hospitals, MRSA emerged in the community independent upon the nosocomial setting (caMRSA). caMRSA possess the capacity to form Panton-Valentine-Leukocidin (PVL) as a special virulence factor. In general PVL-positive S. aureus isolates are associated with necrotizing skin and soft tissue infections as well as with necrotizing pneumonia. caMRSA are less "broad" resistant against different groups of antibiotics as haMRSA and require special attention when performing antimicrobial susceptibility testing. Prevention of further dissemination of caMRSA requires appropriate diagnosis, therapy and sanitation of the carrier state. Hygienic measures have not only to be taken in ambulant treatment but also in households of affected patients.

Molecular epidemiology and household transmission of community-associated methicillin-resistant Staphylococcus aureus in Hong Kong

This study evaluated the clinical and epidemiologic features of individuals with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Hong Kong from January 2004 through December 2005. Twenty-four episodes of skin and soft tissue infections and 1 episode of meningitis due to CA-MRSA were identified. CA-MRSA infections or carriage was found in 6 (13%) of 46 household contacts. A total of 29 isolates were analyzed by the Staphylococcus cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. In addition, polymerase chain reaction detection of the genes encoding Panton-Valentine leukocidin was also carried out. It was observed that 24 had SCCmec IV/IVA and 5 had SCCmec V, and 23 were pvl positive. PFGE analysis clustered all except 1 isolate into 3 pulsed-field types (PFTs), HKU100 through HKU300. The HKU100 isolates had genotype ST30-IV identical to the Southwest Pacific clone. The HKU200 isolates belonged to ST59-V and were multiresistant, including an ermB-mediated macrolide resistance trait, which is characteristic of the predominant CA-MRSA clone in Taiwan. The HKU300 isolates had unique features (ST8, Panton-Valentine leukocidin negative, and SCCmec IVA) typical of CA-MRSA in Japan. In conclusion, CA-MRSA has a propensity to spread within families. Our findings showed that CA-MRSA strains in Hong Kong have diverse genetic backgrounds.

Epidemiology of community-acquired methicillin-resistant Staphylococcus aureus skin infections among healthcare workers in an outpatient clinic

We describe an investigation of soft-tissue infections caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strains in 2 healthcare workers employed in an outpatient clinic for patients with human immunodeficiency virus infection. Cultures of environmental samples from multiple surfaces in the clinic grew toxin-producing CA-MRSA strains, suggesting fomites may play a role in the transmission of these strains of MRSA.

Staphylococcus aureus epidemic in a neonatal nursery: a strategy of infection control

The risk of nosocomial infection due to Staphylococcus aureus in fullterm newborns is higher under hospital conditions where there are overcrowded nurseries and inadequate infection control techniques. We report on an outbreak of skin infection in a Maternity Nursery (May 21, 2000) and the measures undertaken to bring the epidemic under control. These measures included: separating neonates already present in the nursery on August 23, 2000 from ones newly arriving by creating two different cohorts, one of neonates born before this date and one of neonates born later; restricting healthcare workers caring for S. aureus- infected infants from working with non-infected infants; disallowing carrier healthcare workers from caring for patients; introducing contact and droplet precautions (including the routine use of gowns, gloves, and mask); ensuring appropriate disinfection of potential sources of contamination. A representative number of isolates were typed by genomic DNA restriction length polymorphism analysis by means of pulsed-field gel electrophoresis (PFGE). Among the 227 cases of skin lesions, microbiological laboratory analyses confirmed that 175 were staphylococcal infections. The outbreak showed a gradual reduction in magnitude when the overcrowding of the Nursery was reduced by separating the newborns into the two different Nurseries (two cohorts). The genotyping of the strains by PFGE confirmed the nurse-to-newborn transmission of S. aureus. The measures adopted for controlling the S. aureus outbreak can, in retrospect, be assessed to have been very effective.

An outbreak of methicillin-resistant Staphylococcus aureus skin infections resulting from horse to human transmission in a veterinary hospital

There are increasing reports of methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization in horses and evidence that MRSA can be transmitted between horses and humans. The objective of this study was to investigate reports of skin infection in personnel working with a foal with community-associated MRSA colonization and subsequent infection. Clinical diagnostic specimens were collected from individuals reporting skin lesions following contact with the affected foal. Nasal and groin screening swabs were collected from other veterinary personnel that attended a voluntary screening clinic. MRSA skin infections were identified in three neonatal intensive care unit personnel. Nasal colonization was subsequently identified in 10/103 (9.7%) other veterinary hospital personnel. Isolates were indistinguishable by pulsed field gel electrophoresis, classified as Canadian epidemic MRSA-5, possessed SCCmecIV, were negative for the Panton-Valentine leukocidin and were multidrug resistant. Transmission to veterinary personnel despite short-term contact with standard protective barriers highlights the potential importance of MRSA as an emerging zoonotic pathogen, and indicates that further evaluation of interspecies transmission of MRSA and means to prevent zoonotic infection are required.

Can pre-operative skin marking transfer methicillin-resistant Staphylococcus aureus between patients?

National guidelines state that in patients undergoing operations the site of the procedure should be marked. In clinical practice the same marker is used repeatedly. We are not aware of any investigation regarding the theoretical risk of transferring organisms such as methicillin-resistant Staphyloccocus aureus (MRSA) between patients by a skin marker.

In an experimental setting, Penflex and Viomedex skin markers were tested 30 times each after contaminating them with a standard inoculum of MRSA. The survival of the organism on the tip of the markers was assessed by culture on MRSA-indicator nutrient agar plates at 0, 5, 15 and 60 minutes, 24 and 48 hours and at 1, 2, and 3 weeks after contamination.

There was a significant difference between the markers, with the Penflex showing no survival of MRSA after 15 minutes whereas the Viomedex product continued to produce MRSA cultures for up to three weeks.

Spread of Staphylococcus aureus clinical isolates carrying Panton-Valentine leukocidin genes during a 3-year period in Greece

Three collections of Staphylococcus aureus isolates (n = 1,058) were investigated to assess the spread of Panton-Valentine leukocidin (PVL)-producing strains in Greece and their association with skin and soft-tissue infections (SSTIs). The isolates were collected during 2001-2003 from inpatients and outpatients with invasive infections in two distinct geographical areas. Clonal types were identified according to their ClaI-mecA::ClaI-Tn554::pulsed-field gel electrophoresis patterns, and the presence of the lukS-PV and lukF-PV genes was assessed by PCR. In total, 287 (27%) S. aureus isolates carried the PVL genes: 45% of methicillin-resistant S. aureus (MRSA) and 12% of methicillin-sensitive S. aureus (MSSA). All the PVL-positive MRSA isolates belonged to a single clone that was disseminated in the community and hospitals. The PVL-positive MSSA isolates were polyclonal, with 14 of 65 isolates being associated with hospital-acquired infections. The community-acquired isolates were from SSTIs, while the hospital-acquired isolates were associated with surgical wound infections, especially those involving prosthetic devices. Thus, a unique clone of PVL-positive MRSA has spread in both the community and the hospital setting in Greece, and has replaced older clonal types.

Clonal Spread of Staphylococcus aureus with Reduced Susceptibility to Oxacillin in a Dermatological Hospital Unit

In November 2000, we became aware of isolates of Staphylococcus aureus with borderline resistance to oxacillin (BORSA) from patients in the Department of Dermatology, Aarhus University Hospital. The objective was to describe the isolates phenotypically and genotypically and to assess possible transmission routes in order to intervene and prevent further spread. Clonality of the isolates was confirmed by pulsed field gel electrophoresis. Several breaches in infection control procedures were revealed suggesting both direct and indirect transmission between patients. Defective skin barriers, high carrier rates of S. aureus in dermatological patients and high consumption rates of dicloxacillin in the department might facilitate transmission. Following improvement of the general infection control measures, and after reassessment of the antibiotic policy in the department, the outbreak has disappeared.

A clone of methicillin-resistant Staphylococcus aureus among professional football players

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging cause of infections outside of health care settings. We investigated an outbreak of abscesses due to MRSA among members of a professional football team and examined the transmission and microbiologic characteristics of the outbreak strain.

METHODS

We conducted a retrospective cohort study and nasal-swab survey of 84 St. Louis Rams football players and staff members. S. aureus recovered from wound, nasal, and environmental cultures was analyzed by means of pulsed-field gel electrophoresis (PFGE) and typing for resistance and toxin genes. MRSA from the team was compared with other community isolates and hospital isolates.

RESULTS

During the 2003 football season, eight MRSA infections occurred among 5 of the 58 Rams players (9 percent); all of the infections developed at turf-abrasion sites. MRSA infection was significantly associated with the lineman or linebacker position and a higher body-mass index. No MRSA was found in nasal or environmental samples; however, methicillin-susceptible S. aureus was recovered from whirlpools and taping gel and from 35 of the 84 nasal swabs from players and staff members (42 percent). MRSA from a competing football team and from other community clusters and sporadic cases had PFGE patterns that were indistinguishable from those of the Rams' MRSA; all carried the gene for Panton-Valentine leukocidin and the gene complex for staphylococcal-cassette-chromosome mec type IVa resistance (clone USA300-0114).

CONCLUSIONS

We describe a highly conserved, community-associated MRSA clone that caused abscesses among professional football players and that was indistinguishable from isolates from various other regions of the United States.

Transmission of multiple antimicrobial-resistant Staphylococcus intermedius between dogs affected by deep pyoderma and their owners

The occurrence of antimicrobial-resistant Staphylococcus intermedius strains was investigated in 13 dogs affected by deep pyoderma, their owners and 13 individuals without daily contact with dogs (control group). A total of 90 canine and 33 human S. intermedius isolates were typed by pulsed field gel electrophoresis (PFGE) to determine their possible identity. The occurrence of S. intermedius in dog-owners was significantly higher compared with the control group (Fisher's exact test, P=0.03), with S. intermedius being detected in seven dog-owners and in one individual not exposed to dogs. The results of the PFGE analysis showed that six out of 13 (46%) owners carried strains identical to those isolated from their dogs. Strains detected in both dogs and humans were resistant up to five different antimicrobial classes, including penicillins, fusidic acid, macrolides/lincosamides, tetracycline and chloramphenicol. Based on the results of this study, owners of dogs affected by deep pyoderma often carry multiple antimicrobial-resistant strains of S. intermedius occurring in their dogs. Independent of the direction and modalities of transmission, this finding raises questions concerning the possible transfer of resistance genes from canine S. intermedius to human pathogenic staphylococci.

[Genomic typing techniques in a case of skin infection epidemic by Staphylococcus aureus in a newborn unit]

In the present study it has been attempted to characterize the source, the reservoir and the modality of transmission of a skin infection epidemic by Staphylococcus aureus in a Newborn Unit. Every S. aureus isolate from clinician and environmental samples has been submitted to phenotypic typing, by means of antibiotic resistance patterns. The genotype has been analyzed using genomic DNA profile of restriction with Sma I and Pulsed Field Gel Electrophoresis (PFGE). In bacterial infections the epidemiologist nexus can think demonstrated when the stocks isolate from various cases belong to the same one clone. In the Newborn Unit the same one clone of S. aureus has been found on 2 health care workers, on 13 staff bearers characterized, and skin of 5 ill newborn infants. Therefore it has been able to go back to the probable source of infection and to take the right measures.

Methicillin-resistant Staphylococcus aureus infections in correctional facilities---Georgia, California, and Texas, 2001-2003

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are common in hospitals and nursing homes. Because MRSA is resistant to all commonly prescribed beta-lactam antibiotics (e.g., penicillins and cephalosporins), these infections require treatment with alternative antimicrobial drugs. In addition, because antimicrobial drugs usually must be selected before identifying MRSA as the cause of infection, treatment presents a challenge for clinicians. MRSA has emerged recently as a more frequent cause of skin and soft tissue infections in the community, particularly in correctional facilities such as prisons, jails, and detention centers. This report summarizes recent investigations of MRSA transmission among inmates of correctional facilities in Georgia, California, and Texas. Inadequate personal hygiene, barriers to medical care, and other factors contributed to transmission. Information from these investigations has been used in the development of recently released Federal Bureau of Prisons guidance for control of MRSA, which recommends improvements in inmate hygiene, infection control, and targeted antimicrobial treatment.

Implication of a healthcare worker with chronic skin disease in the transmission of an epidemic strain of methicillin-resistant Staphylococcus aureus in a pediatric intensive care unit

This outbreak of colonization of neonates in a 10-bed pediatric intensive care unit illustrates the probable role of a healthcare worker (HCW) in the transmission of methicillin-resistant Staphylococcus aureus, despite good hygienic practices. It raises the issue of preventive exclusion of HCWs affected by chronic skin disease from high-risk units.

Antibiotic-resistant skin infections spreading among gay men, also in prisons

An outbreak of staphylococcus skin infection, causing large boils that are difficult to treat because these bacteria are resistant to many antibiotics, has spread recently among gay men in some cities, and also in certain prisons. In the past this infection occurred mainly in hospitals.

Staphylococcus aureus: colonizing features and influence of an antibacterial treatment in adults with atopic dermatitis

BACKGROUND

The skin of up to 100% of patients with atopic dermatitis (AD) is colonized with Staphylococcus aureus. Of all S. aureus strains isolated from lesional skin, up to 65% have been shown to produce exotoxins with superantigenic properties. Patients colonized with S. aureus have been treated with antibiotics in several open and double-blind placebo-controlled studies, with conflicting results. These studies did not consider the anterior nares as a reservoir of S. aureus, or the possibility of transmission between patients and their contacts. Moreover, adult patients have not so far been investigated.

OBJECTIVES

To investigate the colonizing features of S. aureus in adults with AD and in their contacts, and the effect of an antimicrobial treatment of the patients and their partners.

METHODS

Swabs were taken from the skin and anterior nares of 66 adults with AD. S. aureus strains were screened for the production of exotoxins in 32 patients. Ten patients (two with toxigenic strains, eight with non-toxigenic strains) were treated orally with cefalexin, chlorhexidine ointment was applied to the skin, and the anterior nares were treated with mupirocin ointment. A bath containing potassium permanganate was taken daily. In addition, their partners were treated topically.

RESULTS

Sixty-two of 66 patients (94%) were carriers of S. aureus, and mostly harboured the bacteria on both skin and anterior nares. Ten of 32 (31%) patients were colonized with toxigenic strains. The Severity Scoring in AD (SCORAD) score decreased in nine of 10 patients who received antimicrobial treatment (P < 0.001), and this effect was more pronounced in patients with a baseline SCORAD > 50.

CONCLUSIONS

S. aureus may play an important role as an aggravating factor in adults with AD, as antimicrobial treatment leads to a significant improvement of AD in patients who are colonized with the bacterium.

Adverse events associated with methicillin-resistant Staphylococcus aureus in a nursing home

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) generates concern in nursing homes. Restrictive isolation precautions may be applied for indefinite periods. Adverse events driving these concerns include transmission and infection.

METHODS

The 721-bed Wisconsin Veterans Home in King performs approximately 645 cultures annually. The site, severity, and number of MRSA infections were determined for 69 months. Pulsed-field gel electrophoresis was performed on all initial isolates, followed by a statistical cluster analysis looking for evidence of transmission.

RESULTS

Sixty-seven MRSA infections were identified (1.6 per 100 residents per year); many were polymicrobial, and it was difficult to determine the proportionate role of MRSA in morbidity or mortality. There was an episode of rapidly fatal MRSA septicemia in which empiric antibiotic therapy was ineffective. Twenty-one genetic strains were encountered. Statistical analysis identified 13 clusters of genetically identical strains clustered in time and space (P<.05).

CONCLUSIONS

Infections with MRSA were identified at relatively low rates; however, the etiology of many serious nursing home infections is not determined, especially pneumonia. Statistical analysis revealed clustering and evidence of transmission. Nursing home practitioners should consider MRSA when applying empiric treatment to serious infections. We recommend a program including (1) judicious use of antibiotics, including topical agents, to reduce selection of resistant organisms; (2) obtaining and tracking cultures of infectious secretions to diagnose MRSA infections and focus antibiotic therapy; (3) universal standard secretion precautions because any resident could be a carrier; and (4) a detailed assessment and care plan for the carrier that maximizes containment of secretions and independence in activities. However, basic hygiene cannot be maintained in communal areas by some residents without restriction of activities of daily living.

The significance of nasal carriage of Staphylococcus aureus as risk factor for human skin infections

The present study was designed to investigate the significance and the relationship between nasal carriage of Staphylococcus aureus and staphylococcal skin infections. Thirty-one S. aureus strains, isolated from 12 patients with chronic and recurrent skin infections, one patient with septicemia and one patient with otitis externa were studied. The staphylococcal strains were isolated from the site of infection and from the anterior nares of each patient. The identity of both strains of each pair could be demonstrated by determination of phenotypic properties and by genotyping of the isolates. The phenotypic properties included hemolytic activities, antibiotic resistance data, and the production of enterotoxins. The identity was additionally confirmed by phage-typing, by determination of the size and the number of repeats of the X region of spa gene, by determination of gene polymorphisms of coa gene and by macrorestriction analysis of the chromosomal DNA of the isolates by pulsed-field gel electrophoresis. The present results showed an identity of the S. aureus obtained from anterior nares and from skin infection of each patient indicating the importance of nasal carriage of these bacteria for development of human skin infection.

S. aureus isolation from the lesions, the hands, and the anterior nares of patients with atopic dermatitis

Staphylococcus aureus colonization is common in atopic dermatitis (AD) and can exacerbate the disease. Additionally, some evidence shows that patients with AD may act as reservoirs for S. aureus transmission to others. This study compared S. aureus colonization in AD patients and their caregivers with control patients and their caregivers. Quantitative cultures were obtained from the lesions, clinically normal skin, hands, and anterior nares of 100 patients with AD, 100 controls with other cutaneous disorders, and 200 caregivers. AD patients had a significantly greater carriage of S. aureus from lesional and clinically normal skin as well as the hand. Significant increases in carriage of S. aureus were found in the anterior nares and hands of caregivers of AD patients compared with control caregivers. Topical corticosteroid use did not affect recovery of S. aureus. There was a significant correlation between recovery of S. aureus from lesional skin and recovery from the anterior nares (p = .002) and hands (p < .0001). These findings suggest that the anterior nares and the hands may be important reservoirs and vectors for transmission of S. aureus to lesional skin and to close contacts of these patients.

[Spread and control of methicillin resistant Staphylococcus aureus in a department of dermatology]

Patients with skin diseases caused a spread of methicillin-resistant Staphylococcus aureus (MRSA) to 17 patients in our Department of Dermatology, because of their heavily scaly skin. Patients with severe dermatosis are regularly treated with dicloxacillin. The resistance of bacteria strain concerned suggests a selection because of the use of dicloxacillin in the Department. The strain is sensitive to gentamicin, which differentiates it from strains imported from abroad. Increased hygienic precautions, isolation of infected patients, staff and management efforts and a close contact with the microbiologists prevented MRSA from spreading to other hospital wards.

A double outbreak of exfoliative toxin-producing strains of Staphylococcus aureus in a maternity unit

This report describes a double outbreak of staphylococcal scalded skin syndrome (SSSS) in which two distinct tetracycline-resistant strains of Staphylococcus aureus producing different exfoliative toxins were involved. In the first phase the daytime staff of the delivery unit and eczematous skin conditions in midwives were implicated as the probable source. In the second phase a source within a post-natal ward was suggested with local cross-infection. In the final phase both sources were epidemiologically linked to cases of SSSS. Because early discharge was the policy of the unit many cases presented in the community rather than in the hospital. Confirmation of epidemiological findings was provided by additional laboratory studies. Two distinct strains of S. aureus could be defined, differing in phage-typing patterns, the exfoliative toxin produced, plasmid profile, cadmium resistance and bacteriocin production. Strict care in hand washing with a chlorhexidine-containing detergent was an important control measure.