The natural history of contemporary Staphylococcus aureus nasal colonization in community children.
ABSTRACT: The natural history of contemporary Staphylococcus aureus nasal colonization was evaluated in community children during a 1-year period. Methicillin-susceptible S. aureus nasal carriage was more persistent than methicillin-resistant S. aureus nasal carriage, which was usually self-limited. Children with persistent staphylococcal colonization often carried identical strains. Identification of persistent methicillin-resistant S. aureus carriers might inform strategies for decolonization and reduction of staphylococcal transmission.
Project description:Nasal colonization with Staphylococcus aureus (SA) increases the risk of surgical site infection (SSI). We first (1) determined the prevalence of asymptomatic nasal colonization with SA, (2) assessed trends in methicillin resistance with time, (3) ascertained risk factors for nasal colonization; and (4) correlated SSI to nasal colonization status and procedure. We performed a cross-sectional analysis of SA nasal colonization among healthy preoperative orthopaedic outpatients between 2003-2005 who were within 2 weeks of surgery. Of 284 patients, 86 (30%) carried SA; of these, 81 (94%) were colonized with methicillin-sensitive and five (6%) with methicillin-resistant SA (MRSA). Total SA colonization increased from 25/78 (32%) in 2003 to 37/97 (38%) in 2005, and colonization with MRSA increased from 0/78 (0%) to four of 97 (4%), respectively. We found no associations between nasal carriage and demographics or procedures. Surgical site infection occurred in nine of 282 (3%), four of which were attributable to SA; these included 0/43 (0%) carriers who received decolonization with 2% mupirocin, two of 43 (4.7%) who declined decolonization, and two of 196 (1.0%) who were noncarriers. Nasal colonization with SA, including MRSA, among preoperative orthopaedic outpatients is increasing and their rates reflect community rates. Knowledge of colonization status may be important in decolonization, choosing perioperative or any subsequent empiric antibiotics.
Project description:Staphylococcus aureus (SA) nasal colonization plays a critical role in the pathogenesis of staphylococcal infections and SA eradication from the nares has proven to be effective in reducing endogenous infections. To understand SA nasal colonization and its relation with consequent disease, assessment of nasal carriage dynamics and genotypic diversity among a diverse population is a necessity.We have performed extensive longitudinal monitoring of SA nasal carriage isolates in 109 healthy individuals over a period of up to three years. Longitudinal sampling revealed that 24% of the individuals were persistent SA nasal carriers while 32% were intermittent. To assess the genetic relatedness between different SA isolates within our cohort, multi locus sequence typing (MLST) was performed. MLST revealed that not only were strains colonizing intermittent and persistent nasal carriers genetically similar, belonging to the same clonal complexes, but strain changes within the same host were also observed over time for both types of carriers. More highly discriminating genetic analyses using the hypervariable regions of staphylococcal protein A and clumping factor B virulence genes revealed no preferential colonization of specific SA strains in persistent or intermittent carriers. Moreover, we observed that a subset of persistent and intermittent carriers retained clinically relevant community-acquired methicillin-resistant SA (CA-MRSA) strains in their nares over time.The findings of this study provides added perspective on the nasal carriage dynamics between strains colonizing persistent and intermittent carriers; an area currently in need of assessment given that persistent carriers are at greater risk of autoinfection than intermittent carriers.
Project description:INTRODUCTION:Staphylococcal infections can cause significant morbidity in patients undergoing dialysis. This study evaluated the effects of HIV infection on nasal carriage of Staphylococcus aureus, staphylococcal peritonitis, and catheter infection rates in patients with end-stage renal failure managed with continuous ambulatory peritoneal dialysis (CAPD). METHODS:Sixty HIV-positive and 59 HIV-negative CAPD patients were enrolled and followed up for up to 18 months. S. aureus nasal carriage (detected by nasal swab culture), Staphylococcal peritonitis (diagnosed by clinical presentation, and CAPD effluent Staphylococcal culture and white blood cell count ≥100 cells/µL), and catheter infections (including exit site and tunnel infections) were assessed monthly. RESULTS:At 18 months, S. aureus nasal carriage rates were 43.3% and 30.5% (p = 0.147) and the methicillin-resistant S. aureus (MRSA) nasal carriage rates were 31.7% and 13.6% (p = 0.018) for the HIV-positive and HIV-negative cohorts, respectively. The HIV-positive cohort was associated with increased hazards for staphylococcal peritonitis, (adjusted hazard ratio [AHR] 2.85, 95% confidence interval [CI] 1.19-6.84, p = 0.019) due to increased coagulase-negative staphylococcal (CNS) peritonitis rate in the HIV-positive cohort compared with the HIV-negative cohort (0.435 vs. 0.089 episodes/person-years; AHR 7.64, CI 2.18-26.82, p = 0.001). On multivariable analysis, CD4+ cell count <200 cells/µL, diabetes, and S. aureus nasal carriage were found to be independent predictors of S. aureus peritonitis. CONCLUSIONS:These findings suggest that HIV infection may be a risk factor for MRSA nasal colonization and may increase the risks of CNS peritonitis, while a CD4+ cell count <200 cells/µL and S. aureus nasal carriage may be important predictors of S. aureus peritonitis.
Project description:Investigations regarding Staphylococcus aureus carriage among Brazilian children are scarce. We evaluated the determinants of S. aureus and methicillin-resistant S. aureus (MRSA) nasal carriage in infants attending day care centers (DCCs) and the molecular features of the MRSA strains. A total of 1,192 children aged 2 months to 5 years attending 62 DCCs were screened for S. aureus and MRSA nasal carriage. MRSA isolates were characterized by pulsed-field gel electrophoresis, multilocus sequence typing, spa typing, staphylococcal cassette chromosome (SCC) mec typing and the presence of the Panton-Valentine leukocidin gene. Logistic regression was performed to determine risk factors associated with S. aureus and MRSA colonization. S. aureus and MRSA carriage were detected in 371 (31.1%) and 14 (1.2%) children, respectively. Variables found to be independently associated with an increased risk for S. aureus carriage included being older than 24 months (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.3 to 2.6) and previous DCC attendance (OR, 1.5; 95% CI, 1.0 to 2.2). Having a mother with a high level of education was a protective factor for nasal colonization (OR, 0.4; 95% CI, 0.2 to 0.8). Moreover, we observed that more children carrying MRSA had younger siblings than children not colonized by MRSA. Among the 14 MRSA strains, three SCCmec types (IIIA, IV, and V) were detected, together with a multidrug-resistant dominant MRSA lineage sharing 82.7% genetic similarity with the Brazilian clone (ST239-MRSA-IIIA; ST indicates the sequence type determined by multilocus sequence typing). Although SCCmec type V was recovered from one healthy child who had been exposed to known risk factors for hospital-associated MRSA, its genetic background was compatible with community-related MRSA. Our data suggest that DCC attendees could be contributing to MRSA cross-transmission between health care and community settings.
Project description:Background: The anterior nares are the main ecological niche for Staphylococcus aureus, an important commensal and opportunistic pathogen. Medical students are frequently colonized by a variety of pathogens. Microbial interactions in the human nose can prevent or favor colonization by pathogens, and individuals colonized by pathogens have increased risk of infection and are the source of transmission to other community members or susceptible individuals. According to recent studies, the microbiome from several anatomic areas of healthy individuals varies across different ethnicities. Although previous studies analyzed the nasal microbiome in association with S. aureus carriage, those studies did not provide information regarding ethnicity of participants. Our aim was to assess S. aureus nasal carriage patterns and prevalence among medical students from Colombia, a country of Hispanic origin, and to investigate possible associations of colonization and nasal microbiome composition (bacterial and fungal) in a subgroup of students with known S. aureus carriage patterns. Methods: Nasal swabs from second-year medical students were used to determine prevalence and patterns of S. aureus nasal carriage. Based on microbiological results, we assigned participants into one of three patterns of S. aureus colonization: persistent, intermittent, and non-carrier. Then, we evaluated the composition of nasal microbial communities (bacterial and fungal) in 5 individuals from each carriage category using 16S rRNA and Internal-Transcribed-Spacer sequencing. Results: Prevalence of S. aureus nasal carriage among medical students was 28%. Carriage of methicillin-resistant strains was 8.4% and of methicillin-sensitive strains was 19.6%. We identified 19.6% persistent carriers, 17.5% intermittent carriers, and 62.9% non-carriers. Conclusions: Analysis of nasal microbiome found that bacterial and fungal diversity was higher in individuals colonized by S. aureus than in non-carriers; however, the difference among the three groups was non-significant. We confirmed that fungi were present within the healthy anterior nares at substantial biomass and richness.
Project description:Staphylococcus aureus is an important cause of infection, and brings additional concern with methicillin resistance. In addition, nasal methicillin-resistant Staphylococcus aureus (MRSA) colonization rates among health care workers are higher than that for general population. To determine the prevalence rate and risk factors for the colonization of S. aureus, including MRSA, among janitors working in hospitals in northern Taiwan, we conducted this study.Between June and August, 2014, a total of 186 janitors, 111 working in hospitals and 75 working in non-medical institutions, were recruited. Specimens were obtained from the nares of the subjects for the detection of S. aureus, with a questionnaire completed for each subject. All the S. aureus isolates, including MRSA and methicillin-susceptible S. aureus (MSSA), were further molecularly characterized.The nasal carriage rate of S. aureus was 15.3% for hospital janitors and 13.3% for non-medical janitors. The carriage rate of MRSA was 3.6% for hospital janitors and 1.3% for non-medical janitors. No statistically significant difference was found in the nasal carriage rate of S. aureus (p = 0.707) and MRSA (p = 0.65) between hospital janitors and non-medical janitors. Hospital janitors working in hospital more than 6 years and cleaning microbiologic laboratories were significantly associated with nasal S. aureus colonization. All 5 MRSA isolates carried either staphylococcal cassette chromosome type IV or V and three of them belonged to sequence type (ST) 59, the community clone prevailing in Taiwan. Of the 22 MSSA isolates, six pulsotypes were identified, with one major type for 14 isolates (shared by five STs) and another type for 4 isolates (all belonged to ST 188).Exposure to the hospital environment may not increase the nasal carriage rate of S. aureus, including MRSA, among janitors in hospitals in Taiwan. However, for janitors in the hospital setting, working for more than six years in hospital and cleaning laboratories may be risks factors for carrying S. aureus.
Project description:Determine the prevalence and relatedness of Staphylococcus aureus anterior nares colonization in individuals with community-associated staphylococcal skin and soft-tissue infection (SSTI).Observational cohort.US Army soldiers undergoing infantry training.Trainees who developed SSTI from May 2010 to January 2012.Participants underwent anterior nares culture at the time of presentation for purulent SSTI. We determined the prevalence of S. aureus nasal colonization and strain relatedness between colonizing and clinical isolates with pulsed-field gel electrophoresis (PFGE).We enrolled 1,203 SSTI participants, of whom 508 had culture-confirmed S. aureus SSTI. Overall, 70% (357/508) were colonized with S. aureus. Phenotypically, concordant colonization was more common with methicillin-susceptible S. aureus (MSSA; 56%; 122/218) than methicillin-resistant S. aureus (MRSA) SSTI (41%; 118/290; P < .01). With PFGE, 48% (121 of 254) of clinical-colonizing pairs were indistinguishable, and concordant colonization was more common with MRSA (53%; 92/173) than MSSA SSTI (36%; 29/81; P < .01). Restricting analysis to concomitant MRSA-MRSA or MSSA-MSSA pairs, 92% (92/100) of MRSA SSTI were indistinguishable, and 40% (29/72) MSSA SSTI were indistinguishable (P < .01). All 92 MRSA pairs were USA300.On the phenotypic level, concordant anterior nares colonization with incident staphylococcal SSTI is more common in MSSA than MRSA; however, the opposite is observed when accounting for molecular typing, and MRSA SSTI displays greater concordance. USA300 was responsible for strain concordance with MRSA SSTI. Studies are needed to examine the roles of nasal and extra-nasal carriage, colonization preceding infection, and increased virulence in the pathogenesis of MRSA SSTI.ClinicalTrials.gov identifier: NCT01105767.
Project description:Athletes have a higher risk of infection with Staphylococcus aureus than the general population. Most studies in athletes have included primarily male contact sports participants and have not assessed S. aureus carriage over time. We aimed to examine the epidemiology and risk factors of S. aureus carriage in a cohort of male and female collegiate athletes.We conducted a prospective cohort study of 377 varsity collegiate athletes from August 2008 to April 2010. A baseline questionnaire ascertained risk factors for colonization. Nasal and oropharyngeal swabs were obtained at enrollment and monthly thereafter to detect S. aureus colonization. The primary outcome was S. aureus colonization, both with methicillin-susceptible and methicillin-resistant S. aureus, as defined by bacterial culture and molecular confirmation. Secondary outcomes were time to colonization with S. aureus and carriage profile, defined as non-carrier, intermittent carrier, or persistent carrier.Overall, 224 contact sports and 153 non-contact sports athletes were enrolled. Contact sports athletes had a higher risk of carrying S. aureus over time: They had higher odds of being colonized with MRSA (OR 2.36; 95 % CI 1.13-4.93) and they tended to carry S. aureus for longer periods of time (intermittent carriage OR 3.60; 95 % CI 2.02-6.40; persistent carriage OR 2.39; 95 % CI 1.21-4.72). Athletes engaged in contact sports also acquired S. aureus more quickly (HR 1.61; 95 % CI 1.02-2.55).Staphylococcus aureus carriage was common in contact sports athletes. These findings suggest that efforts to prevent transmission of S. aureus among athletes should be focused on contact sports teams.
Project description:Abstract Background Strategies to interrupt household transmission of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) that target human colonization show mixed results. Our aim was to determine whether home environmental contamination and pet carriage with MRSA were associated with re-colonization or persistent colonization of index patients diagnosed with CA-MRSA skin or soft-tissue infection (SSTI). Methods Index patients from a randomized controlled trial (NCT00966446) that tested household-wide decolonization of people were eligible to participate in this substudy. Before randomization, eight environmental sites and all pets were sampled in the home. Patients were treated by their physician for the initial SSTI between diagnosis (visit 0) and the home visit (visit 1). They provided swabs every 2 weeks for 3 months (7 visits). After broth-enrichment culture, MRSA isolates were PCR-confirmed and spa-typed. Results Of 88 index patients recruited from the main trial, 64 (73%) provided swabs for ?3 visits and were included in this analysis. At visit 1, 41 (64%) households were MRSA contaminated and 6 (9%) had MRSA-positive pet(s). All MRSA-positive pets lived in homes with MRSA environmental contamination. After visit 1, 42 (66%) index patients and their household members were block-randomized to nasal mupirocin and chlorhexidine body wash decolonization. Thirty-seven (58%) index patients had two consecutive negative swabs (de-colonized); 13 (35%) of these later were MRSA-positive (re-colonized). Patients with home contamination had higher rates of re-colonization than those without (Cox proportional hazard ratio 6.0 [95% CI: 1.2, 30.6], P < 0.03). Persistent colonization (all or all but one swab positive) was identified in 6 (9%) of index patients and was associated with identification of matching spa-types in environmental and subsequent human MRSA isolates (P < 0.05). Conclusion In patients with MRSA SSTI, MRSA-contaminated homes, and potentially MRSA-positive pets, are associated with re-colonization and persistent colonization. Future studies are needed to determine whether environmental decontamination can improve the success of household decolonization interventions. Disclosures All authors: No reported disclosures.
Project description:To define the molecular epidemiology of colonization and disease-associated isolates of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA).Laboratory-based comparative study of clinical staphylococcal isolates.We analyzed 255 pediatric CA-MRSA isolates for molecular characteristics associated with colonization and disease. We used polymerase chain reaction to determine the presence of Panton-Valentine Leukocidin and the lantibiotic element, bsaB, and to characterize the staphylococcal cassette chromosome mec type and accessory gene regulator locus. Pulsed-field gel electrophoresis was used to determine genetic relatedness between strains.A total of 150 isolates were obtained from patients with clinical disease (37 invasive infections, 113 noninvasive infections) and 105 from subjects with nasal colonization alone. Of 150 disease-associated isolates, 123 (82%) belonged to pulsed-field gel electrophoresis group USA300, whereas only 19 (18%) of 105 colonization isolates were of the USA300 lineage. Colonization isolates were less likely to possess staphylococcal cassette chromosome mec type IV, Panton-Valentine Leukocidin, or agr type 1 (P < 0.001).Colonization strains of CA-MRSA in children differ significantly from those strains recovered from patients with staphylococcal infections. This suggests that only colonization with specific strain types, rather than methicillin-resistant Staphylococcus aureus colonization in general, increases the risk for CA-MRSA disease.