Longitudinal, strain-specific Staphylococcus aureus introduction and transmission events in households of children with community-associated meticillin-resistant S aureus skin and soft tissue infection: a prospective cohort study.

BACKGROUND: Devising effective, targeted approaches to prevent recurrent meticillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infection requires an understanding of factors driving MRSA acquisition. We comprehensively defined household longitudinal, strain-level S aureus transmission dynamics in households of children with community-associated MRSA skin and soft tissue infection. METHODS: From 2012-15, otherwise healthy paediatric patients with culture-confirmed, community-onset MRSA infections were recruited for the Household Observation of MRSA in the Environment (HOME) prospective cohort study from hospitals and community practices in metropolitan St Louis (MO, USA). Children with health-care-related risk factors were excluded, as determined by evidence of recent hospital admission, an invasive medical device, or residence in a long-term care facility. Household contacts (individuals sleeping in the home ≥four nights per week) and indoor dogs and cats were also enrolled. A baseline visit took place at the index patient's primary home, followed by four quarterly visits over 12 months. At each visit, interviews were done and serial cultures were collected, to detect S aureus from three anatomic sites of household members, two anatomic sites on dogs and cats, and 21 environmental surfaces. Molecular typing was done by repetitive-sequence PCR to define distinct S aureus strains within each household. Longitudinal, multivariable generalised mixed-effects logistic regression models identified factors associated with S aureus acquisition. FINDINGS: Across household members, pets, and environmental surfaces, 1267 strain acquisition events were observed. Acquisitions were driven equally by 510 introductions of novel strains into households and 602 transmissions within households, each associated with distinct factors. Frequent handwashing decreased the likelihood of novel strain introduction into the household (odds ratio [OR] 0·86, credible interval [CrI] 0·74-1·01). Transmission recipients were less likely to own their homes (OR 0·77, CrI 0·63-0·94) and were more likely to share bedrooms with strain-colonised individuals (OR 1·33, CrI 1·12-1·58), live in homes with higher environmental S aureus contamination burden (OR 3·97, CrI 1·96-8·20), and report interval skin and soft tissue infection (OR 1·32, CrI 1·07-1·64). Transmission sources were more likely to share bath towels (OR 1·25, CrI 1·01-1·57). Pets were often transmission recipients, but rarely the sole transmission source. INTERPRETATION: The household environment plays a key role in transmission, a factor associated with skin and soft tissue infection. Future interventions should inclusively target household members and the environment, focusing on straightforward changes in hand hygiene and household sharing behaviours. FUNDING: National Institutes of Health, Agency for Healthcare Research and Quality, Children's Discovery Institute, Burroughs Wellcome Foundation, Defense Advanced Research Projects Agency.

Methicillin-Resistant Staphylococcus aureus: The Effects Are More Than Skin Deep.

OBJECTIVES: To assess the psychosocial effects of a methicillin-resistant Staphylococcus aureus (MRSA) diagnosis on the households of children with MRSA skin and soft tissue infection (SSTI). STUDY DESIGN: We constructed and administered an interview to the primary caregiver within the home of a child with a history of MRSA SSTI. RESULTS: Seventy-six households were enrolled. Survey responses were analyzed and grouped into 4 themes: health behavior changes, disclosure, social interactions, and knowledge/awareness. The most common theme was disclosure; 91% of participants reported sharing their child's MRSA diagnosis with someone outside of the household. Forty-two percent of respondents reported a change in the manner in which household contacts interacted as a result of the index patient's MRSA diagnosis, including isolating the index patient from other children in the household. Many households reported adopting enhanced personal hygiene behaviors and environmental cleaning routines. Thirty-eight percent of participating households reported altering how they interact with people outside of their home, largely to avoid spreading MRSA to vulnerable individuals. In addition, many participants perceived that others regarded them with caution, especially at daycare, whereas other affected households were excluded from family gatherings. CONCLUSION: Primary caregivers of children with MRSA SSTI reported changing their health behaviors, altering their interactions with people outside of their home, and feeling isolated by others in response to their child's MRSA diagnosis. The findings of our study highlight a need for community interventions and education to prevent the negative psychosocial repercussions associated with MRSA.

[Relationship between crowding and community acquired skin and soft tissues infections]. / Relación entre hacinamiento e infecciones comunitarias de piel y partes blandas.

The association of the spread of community infections with poverty and overcrowding is well known. In our hospital, located in José C. Paz, we assist sporadic cases of post-cesarean infections caused by community acquired methicillin-resistant Staphylococcus aureus (CaMRSA). In a prospective study of families treated at our hospital, we investigated the relationship between a history of skin and soft tissue infections (SSTI) and extreme overcrowding defined as households with unsatisfied basic needs type 3 (NBI 3). A total of 264 households were included in the study; 109 (41.3%) had a history of SSTI and 59 (22.3%) were NBI 3. A total of 61.0% of the NBI 3 households and 35.6% of the non-NBI 3 households reported SSTI (p = 0.00047). Using Google Maps, we georeferenced households and identified them on a NBI map adapted from the 2010 demographic census. In neighborhoods with NBI > 9.7%, 51.2% of the households had a history of SSTI. When NBI was < 9.7%, the percentage fell to 31.1% (p = 0.0019). These results are suggestive of an association of SSTI acquired in the community with overcrowding and poverty. The presence of CaMRSA in community SSTIs should be suspected. Vancomycin or clindamycin prophylaxis could be considered when cesarean deliveries are performed in women from areas with high NBI or with a history of SSTI.

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.

Fingernail Carriage of Methicillin-Resistant Staphylococcus aureus and Possible Correlation with Soft Tissue Infections in Children.

OBJECTIVES: Community-associated methicillin-resistant Staphylococcus aureus (MRSA) is a growing problem in the pediatric population, causing many soft tissue infections. This study was designed to examine fingernail carriage of MRSA in children and their caregivers as a possible link to community-associated MRSA soft tissue infections in children. METHODS: We documented the prevalence of MRSA under the fingernails of children and the caregivers of pediatric patients with soft tissue infections and compared the prevalence with MRSA under the fingernails of children and the caregivers of children with no history of soft tissue infections. Children with soft tissue infections and their caregivers (50 subjects) had three fingernails of each hand swabbed and plated and these were compared with a control group of children and their caregivers (150 subjects) who had no history of MRSA or soft tissue infection. RESULTS: Caregivers and children in the study group were more likely than caregivers and the children in the control group to have MRSA under their fingernails (P < 0.05). Soft tissue infections in the study group were found most commonly in the diapering area (66%). CONCLUSIONS: MRSA carriage was evident under the fingernails of children and caregivers. Caregivers and their children who have soft tissue infections are more likely to have MRSA growth under fingernails than caregivers or their children who have no history of MRSA or soft tissue infections. Our study suggests that caregivers could be contributing to soft tissue infections in their children.

Infectious disease, injection practices, and risky sexual behavior among anabolic steroid users.

Anabolic-androgenic steroids (AAS) and other performance-enhancing drugs (PEDs) are commonly misused to increase muscle size and strength, as well as improve physical appearance. Many AAS and certain PEDs are administered via injection and therefore pose a risk for transmission of infectious diseases such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), and skin and soft tissue infections (SSTIs). Further, AAS users may be more likely to take part in high-risk sexual behaviors than non-AAS users. This review explores the prevalence of infectious diseases as well as risky injection practices and sexual behaviors of AAS users in the current literature. A comprehensive MEDLINE search (1984-17 April 2015) for English language reports was performed on AAS users. Ten studies analyzed the prevalence of HIV infection, 6 studies analyzed HBV infection, and 6 studies analyzed HCV infection; 20 studies analyzed injection practices and 7 studies analyzed high-risk sexual behaviors of AAS users. HIV, HBV, HCV, and SSTIs have been associated with AAS users. In particular, HIV infection seems much higher among homosexual male AAS users. AAS users also take part in high-risk injection practices but to a much lower extent than intravenous drug users. AAS users are also more likely to engage in high-risk sexual behaviors than the general population. Clinicians and health-policy leaders may utilize these findings to implement strategies to decrease the spread of infectious diseases.

Emergence of trimethoprim resistance gene dfrG in Staphylococcus aureus causing human infection and colonization in sub-Saharan Africa and its import to Europe.

OBJECTIVES: Co-trimoxazole (trimethoprim/sulfamethoxazole) is clinically valuable in treating skin and soft tissue infections (SSTIs) caused by community-associated methicillin-resistant Staphylococcus aureus (MRSA). The genetic basis of emerging trimethoprim/sulfamethoxazole resistance in S. aureus from Africa is unknown. Such knowledge is essential to anticipate its further spread. We investigated the molecular epidemiology of trimethoprim resistance in S. aureus collected in and imported from Africa. METHODS: Five hundred and ninety-eight human S. aureus isolates collected at five locations across sub-Saharan Africa [Gabon, Namibia, Nigeria (two) and Tanzania] and 47 isolates from travellers treated at six clinics in Europe because of SSTIs on return from Africa were tested for susceptibility to trimethoprim, sulfamethoxazole and trimethoprim/sulfamethoxazole, screened for genes mediating trimethoprim resistance in staphylococci [dfrA (dfrS1), dfrB, dfrG and dfrK] and assigned to spa genotypes and clonal complexes. RESULTS: In 313 clinical and 285 colonizing S. aureus from Africa, 54% of isolates were resistant to trimethoprim, 21% to sulfamethoxazole and 19% to trimethoprim/sulfamethoxazole. We found that 94% of trimethoprim resistance was mediated by the dfrG gene. Of the 47 S. aureus isolates from travellers with SSTIs, 27 (57%) were trimethoprim resistant and carried dfrG. Markers of trimethoprim resistance other than dfrG were rare. The presence of dfrG genes in S. aureus was neither geographically nor clonally restricted. CONCLUSIONS: dfrG, previously perceived to be an uncommon cause of trimethoprim resistance in human S. aureus, is widespread in Africa and abundant in imported S. aureus from ill returning travellers. These findings may foreshadow the loss of trimethoprim/sulfamethoxazole for the empirical treatment of SSTIs caused by community-associated MRSA.

Synchronous recurrence of group B streptococcal late-onset sepsis in twins.

Group B Streptococcus (GBS) remains the leading cause of neonatal sepsis and meningitis in industrialized countries. Whereas the use of intrapartum antibiotic prophylaxis has led to a significant decline in early-onset sepsis, the incidence of late-onset sepsis has remained unchanged. Whether late-onset sepsis usually originates from established mucocutaneous GBS colonization of the infant or whether it results from an acute exogenous GBS infection remains controversial. Here we report on twins who both twice developed GBS sepsis in a strikingly parallel fashion, with both instances originating from a single hypervirulent GBS clone. Factored together, the presentation as cervical soft tissue infection in both cases, the synchronicity of the episodes, and the detection of GBS DNA in breast milk all strongly suggest an enteral mode of transmission with a short incubation period.

Heterogeneity of clinical and environmental isolates of Mycobacterium fortuitum using repetitive element sequence-based PCR: municipal water an unlikely source of community-acquired infections.

M. fortuitum is a rapidly growing mycobacterium associated with community-acquired and nosocomial wound, soft tissue, and pulmonary infections. It has been postulated that water has been the source of infection especially in the hospital setting. The aim of this study was to determine if municipal water may be the source of community-acquired or nosocomial infections in the Brisbane area. Between 2007 and 2009, 20 strains of M. fortuitum were recovered from municipal water and 53 patients' isolates were submitted to the reference laboratory. A wide variation in strain types was identified using repetitive element sequence-based PCR, with 13 clusters of ⩾2 indistinguishable isolates, and 28 patterns consisting of individual isolates. The clusters could be grouped into seven similar groups (>95% similarity). Municipal water and clinical isolates collected during the same time period and from the same geographical area consisted of different strain types, making municipal water an unlikely source of sporadic human infection.

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.

Major West Indies MRSA clones in human beings: do they travel with their hosts?

BACKGROUND: Descriptions of the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) have seldom been produced in the Caribbean, which is a major tourism destination. MATERIALS AND METHODS: Using DNA microarrays and spa typing, we characterized 85 MRSA isolates from human skin and soft-tissue infections from five different islands. RESULTS: In the French West Indies (n = 72), the most frequently isolated clones were the same clones that are specifically isolated from mainland France [Lyon (n = 35) and Geraldine (n = 11) clones], whereas the clones that were most frequently isolated from the other islands (n = 13) corresponded with clones that have a worldwide endemic spread [Vienna/Hungarian/Brazilian (n = 5), Panton Valentine leukocidin-positive USA300 (n = 4), New York/Japan (n = 2), and pediatric (n = 1) clones]. CONCLUSION: The distribution of the major MRSA clones in the French (Guadeloupe and Martinique) and non-French West Indies (Jamaica, Trinidad, and Tobago) is different, and the clones most closely resemble those found in the home countries of the travelers who visit the islands most frequently. The distribution might be affected by tourist migration, which is specific to each island.

Livestock associated MRSA (LA-MRSA) and its relevance for humans in Germany.

Livestock-associated Staphylococcus aureus (LA-MRSA) are mainly associated with the clonal complex (CC) 398. Although having its main reservoir as MRSA in livestock such as pigs, poultry or cattle LA-MRSA CC398 has no pronounced host specificity and can colonize or infect other animals such as horses and dogs and also humans. In German conventional farming systems nasal colonization of the animals and of humans occupationally exposed to them (up to 86%) are frequent. Further human-to-human dissemination in households occurs more rarely in general (∼4% of humans living on farms but without occupational exposition). Nasal colonization with LA-MRSA of humans at hospital admission is found in 0.08-0.2% for Germany in general. However, this proportion is higher in areas with a high density of livestock production such as in northwestern North Rhine-Westphalia or Lower Saxony. LA-MRSA CC398 is not less pathogenic for humans than S. aureus in general. Hence, LA-MRSA accounts for ∼15% of all MRSA isolates from deep-seated skin and soft-tissue infections in the community and for about 0.8-2% of all MRSA isolated from clinical specimens obtained in hospital settings. When introduced into the hospital it can cause postoperative wound infections and even septicemia. Differently from hospital-associated MRSA clones, LA-MRSA CC398 has obviously limited capacity to spread in the nosocomial setting so far (proportion of ∼1.8% among MRSA from nosocomial infections, the proportion among MRSA from blood cultures is ∼1%).

Staphylococcus aureus colonization in children with community-associated Staphylococcus aureus skin infections and their household contacts.

OBJECTIVES: To measure prevalence of Staphylococcus aureus colonization in household contacts of children with acute S aureus skin and soft tissue infections (SSTI), determine risk factors for S aureus colonization in household contacts, and assess anatomic sites of S aureus colonization in patients and household contacts. DESIGN: Cross-sectional study. SETTING: St Louis Children's Hospital Emergency Department and ambulatory wound center and 9 community pediatric practices affiliated with a practice-based research network. PARTICIPANTS: Patients with community-associated S aureus SSTI and S aureus colonization (in the nose, axilla, and/or inguinal folds) and their household contacts. OUTCOME MEASURES: Colonization of household contacts of pediatric patients with S aureus colonization and SSTI. RESULTS: Of 183 index patients, 112 (61%) were colonized with methicillin-resistant S aureus (MRSA); 54 (30%), with methicillin-sensitive S aureus (MSSA); and 17 (9%), with both MRSA and MSSA. Of 609 household contacts, 323 (53%) were colonized with S aureus: 115 (19%) with MRSA, 195 (32%) with MSSA, and 13 (2%) with both. Parents were more likely than other household contacts to be colonized with MRSA (odds ratio, 1.72; 95% CI, 1.12 to 2.63). Methicillin-resistant S aureus colonized the inguinal folds more frequently than MSSA (odds ratio, 1.67; 95% CI, 1.16 to 2.41), and MSSA colonized the nose more frequently than MRSA (odds ratio, 1.75; 95% CI, 1.19 to 2.56). CONCLUSIONS: Household contacts of children with S aureus SSTI had a high rate of MRSA colonization compared with the general population. The inguinal fold is a prominent site of MRSA colonization, which may be an important consideration for active surveillance programs in hospitals.

Staphylococcal colonization of caretakers of children who have community-acquired skin and soft tissue infections.

PURPOSE: Colonization with Staphylococcus aureus is considered a risk factor for the rising incidence of pediatric community-acquired skin and soft tissue infections (CA-SSTIs), and intrafamily spread is thought to be the source of colonization. METHODS: A prospective study was conducted to determine skin and nasal staphylococcal colonization rates among the caretakers of CA-SSTI patients and those of nonabscess controls. A questionnaire regarding risk factors was administered to all participants. Fisher's Exact test and the chi(2) test were used for statistical analysis. RESULTS: Forty-six patients and their caretakers were enrolled in both the study and control groups. Of the caretakers in the study group, 19.6% (n = 9) had staphylococcal colonization of nares; and 2.2% (n = 1), skin. In the control group, 17.4% (n = 8) had nasal colonization; and none had skin colonization. Of the children in the study group, 58.7% (n = 27) had a family history of CA-SSTI compared with only 17.4% (n = 8) of controls (P = .0001). Of CA-SSTI patients, 45.7% (n = 21) had prior abscesses compared with 6.5% (n = 3) of controls (P = .0001). No other risk factor was identified. CONCLUSION: There was no increase in nasal or skin staphylococcal colonization among caretakers of children with CA-SSTI. Family and personal histories of CA-SSTI were the only identified risk factors for CA-SSTI.

Spread of the community-acquired methicillin-resistant Staphylococcus aureus USA300 clone among family members in Japan.

The USA300 clone is a highly-virulent community-acquired methicillin-resistant Staphylococcus aureus, which has been predominant in the United States. In a previous study, we isolated the USA300 clone from an 11-month-old Japanese girl, who lived in Saitama (Japan), and suffered from cellulitis and sepsis, and subsequently osteomyelitis, in 2008. In this study, we searched for the source of such USA300 infection in three related families (the patient's grandfather and grandmother, having a USA300-infected daughter [F2D], and a mother [F3M] who was a sister of F2D's mother). In January, 2008, F3M and her family members visited Hawaii and were treated in a hospital for gastroenteritis (with diarrhea) with an intravenous drip for F3M. After their return to Japan in January, F3M suffered from unusually frequent (more than 10 times) skin soft-tissue infections (SSTIs) until successful chemotherapy in July in Saitama. In the same summer season, SSTI was observed in 7 of 11 family members (63.6%). This dense spread of SSTI was followed by cellulitis and sepsis (USA300-isolated case) in October and subsequent osteomyelitis in December in F2D. After successful chemotherapy for the patient (F2D), no new SSTI cases were observed among the family members, and no USA300 colonization was observed when examined in December, 2009. The data suggest the first spread of the USA300 clone in Japan with related families at the core and that such USA300 spread in the community is likely to have occurred in the summer season in Japan.

The impact of household transmission on duration of outpatient colonization with methicillin-resistant Staphylococcus aureus.

We identified eight consecutive patients who presented with a skin or soft tissue infection due to MRSA. Of seven household members of these cases, three were colonized with MRSA. The mean duration of MRSA colonization in index cases was 33 days (range 14-104), while mean duration of colonization in household cases was 54 days (range 12-95). There was a borderline significant association between having a concurrent colonized household member and a longer duration of colonization (mean 44 days vs. 26 days, P=0.08).

A cluster of community-acquired methicillin-resistant Staphylococcus aureus infections in hospital security guards.

We investigated a cluster of methicillin-resistant Staphylococcus aureus soft-tissue infections in 5 security guards employed in a hospital emergency department. An epidemiologic investigation and molecular subtyping of isolates revealed that the source was a patient and that a community-acquired methicillin-resistant S. aureus strain (USA-300) was transmitted to healthcare workers through physical contact.

Methicillin-resistant Staphylococcus aureus infections.

Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infection is epidemic in the community, differs from nosocomial MRSA in virulence, mechanisms, and antibiotic susceptibility, and exhibits diverse and often unique pathologic characteristics. The community-acquired MRSA USA 300 strains are transmitted largely by person-to-person contact and cause characteristic soft-tissue abscesses and, less commonly, other sometimes unusual and serious infections including a necrotizing pneumonia, and other necrotic infections such as necrotizing fasciitis, pelvic thrombophlebitis, and septic phlebitis. This MRSA 300 family remains susceptible to drugs active against nosocomial MRSA (ie, vancomycin, linezolid, daptomycin) and is often susceptible to trimethoprim-sulfamethoxazole, doxycycline, and clindamycin. Recent epidemiologic data indicate that nosocomial MRSA (eg, mainly USA 100) strains are also present in the community and that MRSA USA 300 strains are present in hospital settings, with both families found in intermediate frequency in health care-associated settings (eg, nursing homes, dialysis centers). More work is needed to identify effective barrier precautions to limit their spread.