Incidence and persistence of Staphylococcus aureus nasal colonization in a community sample of HIV-infected and -uninfected drug users

Factors associated with the risk of upper respiratory tract bacterial infections among HIV-positive patients

Background

The risk and characteristics of upper respiratory tract (URT) bacterial infections (URT-BI) among HIV (+) patients is understudied. We analyzed factors associated with its occurrence and the spectrum of culturable pathogens among patients routinely followed at the HIV Out-Patient Clinic in Warsaw.

Methods

All HIV (+) patients with available URT swab culture were included into analyses. Patients were followed from the day of registration in the clinic until first positive URT swab culture or last clinical visit from January 1, 2007 to July 31, 2016. Cox proportional hazard models were used to identify factors associated with positive URT swabs culture (those with p<0.1 in univariate included into multivariable).

Results

In total 474 patients were included into the analyses, 166 with culturable URT swab. In general, 416 (87.8%) patients were male, 342 (72.1%) were infected through MSM contact, 253 (53.4%) were on antiretroviral therapy. Median follow-up time was 3.4 (1.3–5.7) years, age 35.2 (30.6–42.6) years and CD4+ count 528 (400–685) cells/μl. The most common cultured bacteria were S. aureus (40.4%) and S. pyogenes (13.9%) (Table 1). Patients with culturable URT-BI were more likely to be MSM (68.5% vs 78.9%; p<0.016), have detectable viral load (20.9% vs 12.0%; p<0.0001) and CD4+ cell count <500 cells/μl (55.2% vs 39.0%; p = 0.003) (Table 2). In multivariate survival analyses detectable viral load (HR3.13; 95%Cl: 2.34–4.19) and MSM (1.63;1.09–2.42) were increasing, but older age (0.63;0.58–0.69, per 5 years older) and higher CD4+ count (0.90;0.85–0.95, per 100 cells/μl) decreasing the risk of culturable URT-BI (Table 2).

Conclusions

Culturable URT-BI are common among HIV-positive patients with high CD4+ count. Similarly to general population most common cultured bacteria were S. aureus and S. pyogenes. Risk factors identified in multivariate survival analysis indicate that younger MSM patients with detectable HIV viral load are at highest risk. In clinical practice this group of patients requires special attention.

Staphylococcus aureus colonisation in HIV-infected patients: Incidence, risk factors and subsequent skin- and soft-tissue infections

We evaluated the incidence and risk factors of Staphylococcus aureus colonisation in 300 treatment-naïve HIV patients. Swabs from anterior nares and pharynx were cultured. Eighty-eight patients (29.3%) were colonised with S. aureus (47.7% nasal, 23.8% pharyngeal and 28.5% at both sites), which yielded 112 isolates. Methicillin-resistant S. aureus was detected in 25.9% (29/112) of isolates. Panton-Valentine leucocidin gene was present in 18.8% (21/112) of isolates. Multiple logistic regression analysis identified CD4 count <200 cells/mm3, public bath use, alcohol intake and other sexually transmitted infections as independent predictors for S. aureus colonisation. On follow-up, 22.7% of patients with S. aureus colonisation developed skin- and soft-tissue infections. Strategies for behavioural changes would be helpful in controlling S. aureus colonisation and subsequent infection.

The association between community-associated Staphylococcus aureus colonization and disease: a meta-analysis

Background

Colonization with Staphylococcus aureus is a well-defined risk factor for disease in hospitals, which can range from minor skin infections to severe, systemic diseases. However, the generalizability of this finding has not been thoroughly investigated outside of the hospital environment. We aimed to assess the role of S. aureus colonization as a risk factor for disease in the community.

Methods

We performed a meta-analysis of observational studies and searched PubMed for articles published between December 1979 and May 23, 2016. We included cohort, cross-sectional, and case-control studies that reported quantitative estimates of both S. aureus colonization and disease statuses of all study subjects. We excluded studies on recently hospitalized subjects, long-term care facilities, surgery patients, dialysis patients, hospital staff, S. aureus outbreaks, and livestock-associated infections. Our meta-analysis was performed using random-effects analysis to obtain pooled odds ratios (ORs) to compare the odds of S. aureus disease with respect to S. aureus colonization status.

Results

We identified 3477 citations, of which 12 articles on 6998 subjects met the eligibility criteria. Overall, subjects colonized with S. aureus were more likely to progress to disease than those who were non-colonized: (OR 1.87, 95% CI 1.21–2.88, n = 7 studies). We observed a larger effect with methicillin-resistant S. aureus colonization (7.06, 4.60–10.84, n = 7 studies). However, the methicillin-sensitive S. aureus colonization was not associated with greater odds of disease (1.20, 0.69–2.06, n = 4 studies). Heterogeneity was present across studies in all of the subgroups: S. aureus (I² = 95.0%, χ² = 120.3, p < 0.001), MRSA (I² = 92.8%, χ² = 82.8, p = p < 0.001), and MSSA (I² = 86.3%, χ² = 21.8, p < 0.001).

Conclusions

While the majority of papers individually support the assumption that colonization is a risk factor for S. aureus disease in the general population, there is marked heterogeneity between studies and further investigation is needed to identify the major sources of this variance. There is a shortage of literature addressing this topic in the community setting and a need for further research on colonization as a focus for disease prevention.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-2990-3) contains supplementary material, which is available to authorized users.

Prevalence and risk factors for MRSA nasal colonization among persons experiencing homelessness in Boston, MA

Homeless individuals face an elevated risk of methicillin-resistant Staphylococcus aureus (MRSA) infection. Identifying the prevalence and risk factors for MRSA nasal colonization may reduce infection risk. A cross-sectional study was conducted at a health clinic for homeless persons in Boston, MA, USA (n=194). In-person interviews and nasal swab specimens were collected. MRSA isolates were genotyped using pulse-field gel electrophoresis (PFGE) and assessed for antibiotic susceptibility. The prevalence of MRSA nasal colonization was 8.3 %. Seventy-five percent of isolates reflected clonal similarity to USA300. USA100 (18.8 %) and USA500 (6.3 %) were also recovered. Resistance to erythromycin (81.3 %), levofloxacin (31.3 %) and clindamycin (23.1 %) was identified. Recent inpatient status, endocarditis, haemodialysis, heavy drinking, not showering daily and transience were positively associated with MRSA nasal colonization. Carriage of community-acquired MRSA strains predominated in this population, although nosocomial strains co-circulate. Attention to behavioural and hygiene-related risk factors, not typically included in MRSA prevention efforts, may reduce risk.

Prevalence of Staphylococcus aureus Nasal Carriage in Human Immunodeficiency Virus-Infected and Uninfected Children in Botswana: Prevalence and Risk Factors

AbstractStaphylococcus aureus is an important cause of morbidity and mortality in children in sub-Saharan Africa (SSA). A major risk factor for staphylococcal infection is S. aureus colonization of the anterior nares. We sought to define risk factors for S. aureus carriage and characterize antimicrobial resistance patterns in children in Botswana. A cross-sectional study was conducted at two clinical sites in southern Botswana. Patients under 18 years of age underwent two nasal swabs and brief interviews, 4 weeks apart. Standard microbiological techniques were used. For persistent carriers, S. aureus was isolated from swabs at both time points, and for intermittent carriers, S. aureus was isolated from only one swab. Poisson regression with robust variance estimator was used to compare prevalence of carriage and the resistance phenotypes. Among 56 enrollees, prevalence of S. aureus colonization was 55% (N = 31), of whom 42% (N = 13) were persistent carriers. Of human immunodeficiency virus-infected children, 64% (N = 9) were carriers. Risk factors for nasal carriage included a history of tuberculosis (prevalence ratio [PR] = 1.60; 95% confidence interval [CI] = 1.02, 2.51; P = 0.040) and closer proximity to health care (PR = 0.89; 95% CI = 0.80, 0.99; P = 0.048). Prior pneumonia was more common among persistent rather than intermittent carriers (PR = 2.64; 95% CI = 1.64, 4.23; P < 0.001). Methicillin-resistant S. aureus (MRSA) prevalence was 13%. Of isolates tested, 16% were resistant to three or more drugs (N = 7/44). In summary, children in southern Botswana are frequently colonized with S. aureus. Antibiotic resistance, especially MRSA, is also widespread. Antibiotic recommendations for treatment of staphylococcal infections in SSA should take cognizance of these resistance patterns.

Staphylococcus aureus nasal colonization among HIV-infected adults in Botswana: prevalence and risk factors

We sought to determine the clinical and epidemiologic determinants of Staphylococcus aureus nasal colonization in HIV-infected individuals at two outpatient centers in southern Botswana. Standard microbiologic techniques were used to identify S. aureus and methicillin-resistant S. aureus (MRSA). In a sample of 404 HIV-infected adults, prevalence of S. aureus nasal carriage was 36.9% (n = 152) and was associated with domestic overcrowding and lower CD4 cell count. MRSA prevalence was low (n = 13, 3.2%), but more common among individuals with asthma and eczema. The implications of these findings for HIV management are discussed.

Staphylococcus epidermidis Protection Against Staphylococcus aureus Colonization in People Living With Human Immunodeficiency Virus in an Inner-City Outpatient Population: A Cross-Sectional Study

Background.

People living with human immunodeficiency virus (PLWH) have been disproportionally affected by methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection, in particular by clones USA300 and USA500. However, the contribution of epidemiological, bacterial, and immunological risk factors to the excess of S aureus in PLWH remain incompletely understood.

Methods.

In this cross-sectional study, we determined the prevalence and molecular epidemiology of S aureus colonization in 93 PLWH attending an urban human immunodeficiency virus (HIV) clinic. Participants completed a structured interview assessing demographic information and risk factors for MRSA. Swabs were obtained from the nose, throat, and groin and cultured for S aureus and Staphylococcus epidermidis.

Results.

Most participants had well controlled HIV infection (89, 96% CD4 >200). Thirty-six (39%) individuals were colonized with S aureus at 1 or more body sites, including 6 (6%) with MRSA. Regular gym use was a risk factor for S aureus but not MRSA carriage. In contrast, S epidermidis was present in almost all individuals (n = 84, 90%), predominantly in the nares (n = 66, 71%). Using generalized estimating equation models, we observed that the odds of S aureus colonization were significantly and drastically reduced when S epidermidis was detected (P = .0001). After controlling for site, gender, and age, we identified that the odds of S aureus colonization were 80% less if S epidermidis was present (adjusted odds ratio, 0.20; 95% confidence interval, .09–.45; P < .0001).

Conclusions.

Taken together, we observed a lower prevalence of S aureus and MRSA colonization than has been previously reported in PLWH. In this cohort, colonization with S epidermidis was protective against S aureus colonization.

HIV and colonization with Staphylococcus aureus in two maximum-security prisons in New York State

OBJECTIVE

To evaluate the association between HIV and Staphylococcus aureus colonization after confounding by incarceration is removed.

METHOD

A cross sectional stratified study of all HIV infected and a random sample of HIV-uninfected inmates from two maximum-security prisons in New York State. Structured interviews were conducted. Anterior nares and oropharyngeal samples were cultured and S. aureus isolates were characterized. Log-binomial regression was used to assess the association between HIV and S. aureus colonization of the anterior nares and/or oropharynx and exclusive oropharynx colonization. Differences in S. aureus strain diversity between HIV-infected and uninfected individuals were assessed using Simpson's Index of Diversity.

RESULTS

Among 117 HIV infected and 351 HIV uninfected individuals assessed, 47% were colonized with S. aureus and 6% were colonized with methicillin resistant S. aureus. The prevalence of S. aureus colonization did not differ by HIV status (PR = 0.99, 95% CI = 0.76-1.24). HIV infected inmates were less likely to be exclusively colonized in the oropharynx (PR = 0.55, 95% CI = 0.30-0.99). Spa types t571 and t064 were both more prevalent among HIV infected individuals, however, strain diversity was similar in HIV infected and uninfected inmates.

CONCLUSIONS

HIV infection was not associated with S. aureus colonization in these maximum-security prison populations, but was associated with decreased likelihood of oropharyngeal colonization. Factors that influence colonization site require further evaluation.

Randomized, Double-Blind, Placebo-Controlled Study on Decolonization Procedures for Methicillin-Resistant Staphylococcus aureus (MRSA) among HIV-Infected Adults

BACKGROUND

HIV-infected persons have increased risk of MRSA colonization and skin and soft-tissue infections (SSTI). However, no large clinical trial has examined the utility of decolonization procedures in reducing MRSA colonization or infection among community-dwelling HIV-infected persons.

METHODS

550 HIV-infected adults at four geographically diverse US military HIV clinics were prospectively screened for MRSA colonization at five body locations every 6 months during a 2-year period. Those colonized were randomized in a double-blind fashion to nasal mupirocin (Bactroban) twice daily and hexachlorophene (pHisoHex) soaps daily for 7 days compared to placeboes similar in appearance but without specific antibacterial activity. The primary endpoint was MRSA colonization at 6-months post-randomization; secondary endpoints were time to MRSA clearance, subsequent MRSA infections/SSTI, and predictors for MRSA clearance at the 6-month time point.

RESULTS

Forty-nine (9%) HIV-infected persons were MRSA colonized and randomized. Among those with 6-month colonization data (80% of those randomized), 67% were negative for MRSA colonization in both groups (p = 1.0). Analyses accounting for missing 6-month data showed no significant differences could have been achieved. In the multivariate adjusted models, randomization group was not associated with 6-month MRSA clearance. The median time to MRSA clearance was similar in the treatment vs. placebo groups (1.4 vs. 1.8 months, p = 0.35). There was no difference on subsequent development of MRSA infections/SSTI (p = 0.89). In a multivariable model, treatment group, demographics, and HIV-specific factors were not predictive of MRSA clearance at the 6-month time point.

CONCLUSION

A one-week decolonization procedure had no effect on MRSA colonization at the 6-month time point or subsequent infection rates among community-dwelling HIV-infected persons. More aggressive or novel interventions may be needed to reduce the burden of MRSA in this population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00631566.

Specific Behaviors Predict Staphylococcus aureus Colonization and Skin and Soft Tissue Infections Among Human Immunodeficiency Virus-Infected Persons

Background.  Few data exist on the incidence and risk factors of Staphylococcus aureus colonization and skin and soft tissue infections (SSTIs) among patients infected with human immunodeficiency virus (HIV). Methods.  Over a 2-year period, we prospectively evaluated adults infected with HIV for incident S aureus colonization at 5 body sites and SSTIs. Cox proportional hazard models using time-updated covariates were performed. Results.  Three hundred twenty-two participants had a median age of 42 years (interquartile range, 32-49), an HIV duration of 9.4 years (2.7-17.4), and 58% were on highly active antiretroviral therapy (HAART). Overall, 102 patients (32%) became colonized with S aureus with an incidence rate of 20.6 (95% confidence interval [CI], 16.8-25.0) per 100 person-years [PYs]. Predictors of colonization in the final multivariable model included illicit drug use (hazard ratios [HR], 4.26; 95% CI, 1.33-13.69) and public gym use (HR 1.66, 95% CI, 1.04-2.66), whereas antibacterial soap use was protective (HR, 0.50; 95% CI, 0.32-0.78). In a separate model, perigenital colonization was associated with recent syphilis infection (HR, 4.63; 95% CI, 1.01-21.42). Fifteen percent of participants developed an SSTI (incidence rate of 9.4 cases [95% CI, 6.8-12.7] per 100 PYs). Risk factors for an SSTI included incident S aureus colonization (HR 2.52; 95% CI, 1.35-4.69), public shower use (HR, 2.59; 95% CI, 1.48-4.56), and hospitalization (HR 3.54; 95% CI, 1.67-7.53). The perigenital location for S aureus colonization was predictive of SSTIs. Human immunodeficiency virus-related factors (CD4 count, HIV RNA level, and HAART) were not associated with colonization or SSTIs. Conclusions.  Specific behaviors, but not HIV-related factors, are predictors of colonization and SSTIs. Behavioral modifications may be the most important strategies in preventing S aureus colonization and SSTIs among persons infected with HIV.

Bacteremia, Sepsis, and Infective Endocarditis Associated with Staphylococcus aureus

Bacteremia and infective endocarditis (IE) are important causes of morbidity and mortality associated with Staphylococcus aureus infections. Increasing exposure to healthcare, invasive procedures, and prosthetic implants has been associated with a rising incidence of S. aureus bacteremia (SAB) and IE since the late twentieth century. S. aureus is now the most common cause of bacteremia and IE in industrialized nations worldwide and is associated with excess mortality when compared to other pathogens. Central tenets of management include identification of complicated bacteremia, eradicating foci of infection, and, for many, prolonged antimicrobial therapy. Evolving multidrug resistance and limited therapeutic options highlight the many unanswered clinical questions and urgent need for further high-quality clinical research.

Prevalence and behavioural risk factors of Staphylococcus aureus nasal colonization in community-based injection drug users

The aims of this study were to identify Staphylococcus aureus nasal colonization prevalence, behavioural risk factors, and to determine staphylococcal protein A (spa) types in community-based injection drug users (IDUs). Nasal swabs were collected and methicillin susceptibility testing and spa/SCCmec typing were performed on S. aureus isolates. Generalized estimating equations were used to report adjusted odds ratios and 95% confidence intervals. Of the 440 participants, 24·1% were colonized and 5·7% had methicillin-resistant S. aureus (MRSA). Colonization was associated with age, employment/marital status, and the presence of scabs but not with sexually transmitted disease co-infection, HIV status, antibiotic use, hospitalization, or drug treatment programme participation. The USA300 MRSA clone spa types were most common, but 15/49 spa types were new to one of the international databases. Community-based IDUs appear to have different risk factors compared to IDUs from clinical studies. In addition, the number of newly identified spa types indicates a diverse, understudied population.

Prevalence and characterization of methicillin-resistant Staphylococcus aureus isolates from healthy university student athletes

BACKGROUND

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has been increasing in the general population, and there is concern that close or physical contact, such as in professional and collegiate sports, may increase spread of MRSA. We sought to determine the prevalence of MRSA colonization of male and female athletes from 9 different sports at a major, Division I University during a 12-week period, and determine the USA and SCCmec type from select isolates.

METHODS

Swabs for culture of MRSA were obtained from nasal, axillary, and inguinal sites from healthy, asymptomatic student athletes and support staff each week for 12 weeks. Select MRSA isolates were typed by pulsed field gel electrophoresis (PFGE), and the genes encoding for MecA, cassette chromosome recombinase (Ccr), and several toxins were determined by multiplex polymerase chain reaction (PCR). Discrepant results were clarified by multi-locus sequence typing (MLST) and spa typing.

RESULTS

Thirty-five percent (78/223) of test subjects were positive for MRSA during the study period, resulting in isolation of 139 MRSA isolates. However, 47% (37/78) of MRSA-positive participants carried MRSA in axillary or inguinal sites, but not in the anterior nares. There was significant correlation between MRSA carriage and participation in wrestling (76%, 19/25; adjusted odds ratio 29.7, 95% CI 5.8-151.5) and baseball (44%, 17/39; adjusted odds ratio 4.4, 95% CI 1.1- 17.4), compared with a staff prevalence of 18.1% (4/22), but other factors were not examined. Multiplex PCR analysis indicated that of the 32 isolates examined 26 could be typed, and all of these carried the SCCmec type IV cassette. PFGE typing identified USA types 300, 400, 500, 700, and 800. However, one isolate was not a known USA type, but was identified as a novel ST951 by MLST, and as spa type t216. Of the strains typed from the same individual, there was consistency, but also variation and alternation of the SCCmec and spa types isolated from individual subjects. Various staphylococcal toxin genes were identified in 31 of the 32 isolates analyzed.

CONCLUSIONS

Colonization by MRSA was greater in some student athletes than the average carriage rate for the general population, and only 53% of MRSA carriers were identified by nasal cultures. Carriage of MRSA clones on the same individual and transmission to contacts could vary over time, indicating colonization can be a dynamic process that may be difficult to control.

Staphylococcus aureus Colonization: Modulation of Host Immune Response and Impact on Human Vaccine Design

In apparent contrast to its invasive potential Staphylococcus aureus colonizes the anterior nares of 20–80% of the human population. The relationship between host and microbe appears particularly individualized and colonization status seems somehow predetermined. After decolonization, persistent carriers often become re-colonized with their prior S. aureus strain, whereas non-carriers resist experimental colonization. Efforts to identify factors facilitating colonization have thus far largely focused on the microorganism rather than on the human host. The host responds to S. aureus nasal colonization via local expression of anti-microbial peptides, lipids, and cytokines. Interplay with the co-existing microbiota also influences colonization and immune regulation. Transient or persistent S. aureus colonization induces specific systemic immune responses. Humoral responses are the most studied of these and little is known of cellular responses induced by colonization. Intriguingly, colonized patients who develop bacteremia may have a lower S. aureus-attributable mortality than their non-colonized counterparts. This could imply a staphylococcal-specific immune “priming” or immunomodulation occurring as a consequence of colonization and impacting on the outcome of infection. This has yet to be fully explored. An effective vaccine remains elusive. Anti-S. aureus vaccine strategies may need to drive both humoral and cellular immune responses to confer efficient protection. Understanding the influence of colonization on adaptive response is essential to intelligent vaccine design, and may determine the efficacy of vaccine-mediated immunity. Clinical trials should consider colonization status and the resulting impact of this on individual patient responses. We urgently need an increased appreciation of colonization and its modulation of host immunity.

A systematic literature review and meta-analysis of factors associated with methicillin-resistant Staphylococcus aureus colonization at time of hospital or intensive care unit admission

OBJECTIVE

Screening for methicillin-resistant Staphylococcus aureus (MRSA) in high-risk patients is a legislative mandate in 9 US states and has been adopted by many hospitals. Definitions of high risk differ among hospitals and state laws. A systematic evaluation of factors associated with colonization is lacking. We performed a systematic review of the literature to assess factors associated with MRSA colonization at hospital admission.

DESIGN

We searched MEDLINE from 1966 to 2012 for articles comparing MRSA colonized and noncolonized patients on hospital or intensive care unit (ICU) admission. Data were extracted using a standardized instrument. Meta-analyses were performed to identify factors associated with MRSA colonization.

RESULTS

We reviewed 4,381 abstracts; 29 articles met inclusion criteria (n = 76,913 patients). MRSA colonization at hospital admission was associated with recent prior hospitalization (odds ratio [OR], 2.4 [95% confidence interval (CI), 1.3-4.7]; P < .01), nursing home exposure (OR, 3.8 [95% CI, 2.3-6.3]; P < .01), and history of exposure to healthcare-associated pathogens (MRSA carriage: OR, 8.0 [95% CI, 4.2-15.1]; Clostridium difficile infection: OR, 3.4 [95% CI, 2.2-5.3]; vancomycin-resistant Enterococci carriage: OR, 3.1 [95% CI, 2.5-4.0]; P < .01 for all). Select comorbidities were associated with MRSA colonization (congestive heart failure, diabetes, pulmonary disease, immunosuppression, and renal failure; P < .01 for all), while others were not (human immunodeficiency virus, cirrhosis, and malignancy). ICU admission was not associated with an increased risk of MRSA colonization (OR, 1.1 [95% CI, 0.6-1.8]; P = .87).

CONCLUSIONS

MRSA colonization on hospital admission was associated with healthcare contact, previous healthcare-associated pathogens, and select comorbid conditions. ICU admission was not associated with MRSA colonization, although this is commonly used in state mandates for MRSA screening. Infection prevention programs utilizing targeted MRSA screening may consider our results to define patients likely to have MRSA colonization.

Nasal carriage of Streptococcus pneumoniae serotypes and Staphylococcus aureus in Streptococcus pneumoniae-vaccinated and non-vaccinated young children

Since the implementation of Streptococcus pneumoniae (SPn) conjugate vaccination (PCV), non-vaccine types have prevailed in invasive pneumococcal disease (IPD), and an increase in Staphylococcus aureus (SA) burden has been suggested. Here, we assess the epidemiology of SA and SPn nasal carriage in 620 children at day-care centres; 141 of these children had received 1-4 PCV7 doses. A higher vaccine dosage was associated with non-vaccine-type SPn carriage. Of all SPn isolates, 45% were PCV7 types, 1% were additional PCV10 types and 22% were the three additional PCV13 types. SA carriage was inversely associated with vaccine-type SPn carriage. SPn serotype 19A showed higher SA co-carriage rates compared to other SPn serotypes. PCV7 implementation does not prevent children from being part of the IPD-related SPn transmission chain. These results contribute to the monitoring of SA- and SPn-related disease and add to the debate on the current national vaccination policy that recently included a change from PCV7 to PCV10.

Prevalence, persistence, and microbiology of Staphylococcus aureus nasal carriage among hemodialysis outpatients at a major New York Hospital

The study aimed to determine the natural history of Staphylococcus aureus nasal colonization in hemodialysis outpatients. Surveillance cultures were taken from patients presenting for hemodialysis or routine care to identify S. aureus nasal carriers. A prospective cohort study was performed to identify risks for persistent colonization. Detailed microbiologic and molecular studies of colonizing isolates were performed. Only 23/145 (15.9%) dialysis patients were persistently colonized, and only HIV-positive status was associated with persistence (P = 0.05). Prior hospitalization was the only risk factor for methicillin-resistant S. aureus carriage (OR 2.5, P = 0.03). In isolates from patients with ≤ 42 days of vancomycin exposure, vancomycin minimum bactericidal concentrations (MBCs) increased with duration of exposure. Among dialysis patients, S. aureus colonization was limited and transient; only HIV status was associated with persistence. Nevertheless, duration of vancomycin exposure was associated with increasing vancomycin MBCs. Vancomycin exposure in S. aureus carriers may be involved in increasing resistance.

The NOSE study (nasal ointment for Staphylococcus aureus eradication): a randomized controlled trial of monthly mupirocin in HIV-infected individuals

BACKGROUND

HIV-positive patients at HELP/PSI, Inc, an in-patient drug rehabilitation center, had a high baseline prevalence of Staphylococcus aureus colonization (49%) and incidence of infection (17%) in a previous year-long study.

METHODS

A randomized, double-blinded, placebo-controlled study was conducted to determine whether repeated nasal application of mupirocin ointment would decrease the odds of S. aureus nasal colonization in 100 HELP/PSI patients over an 8-month period. A 5-day course of study drug was given monthly, and colonization was assessed at baseline and 1 month after each treatment. S. aureus infection was a secondary outcome.

RESULTS

In repeated-measures analysis, mupirocin reduced the odds of monthly S. aureus nasal colonization by 83% compared with placebo [adjusted odds ratio (ORadj) = 0.17; P < 0.0001]. Subjects colonized at study entry had a 91% reduction in subsequent colonization (ORadj = 0.09; P < 0.0001). Mupirocin also suppressed S. aureus colonization in subjects not colonized at baseline (ORadj = 0.23; P = 0.006). There was no difference in infection rates between the mupirocin and placebo groups (hazard ratio = 0.49, P = 0.29).

CONCLUSIONS

Monthly application of nasal mupirocin significantly decreased S. aureus colonization in HIV patients in residential drug rehabilitation. Monthly mupirocin application has a potential role in long-term care settings or in HIV-positive patients with high rates of S. aureus colonization and infection.

Methicillin-resistant Staphylococcus aureus in HIV-infected patients

Concordant with the emergence of methicillin-resistant Staphylococcus aureus (MRSA) in the community setting, colonization and infections with this pathogen have become a prevalent problem among the human immunodeficiency virus (HIV)-positive population. A variety of different host- and, possibly, pathogen-related factors may play a role in explaining the increased prevalence and incidence observed. In this article, we review pathophysiology, epidemiology, clinical manifestations, and treatment of MRSA in the HIV-infected population.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Staphylococcus aureus in the community: colonization versus infection

Background

Antibiotic-resistant Staphylococcus aureus infections have increased dramatically in the community, yet S. aureus nasal colonization has remained stable. The objectives of this study were to determine if S. aureus colonization is a useful proxy measure to study disease transmission and infection in community settings, and to identify potential community reservoirs.

Methodology/Principal Findings

Randomly selected households in Northern Manhattan, completed a structured social network questionnaire and provided nasal swabs that were typed by pulsed field gel electrophoresis to identify S. aureus colonizing strains. The main outcome measures were: 1) colonization with S. aureus; and 2) recent serious skin infection. Risk factor analyses were conducted at both the individual and the household levels; logistic regression models identified independent risks for household colonization and infection.

Results

321 surveyed households contained 914 members. The S. aureus prevalence was 25% and MRSA was 0.4%. More than 40% of households were colonized. Recent antibiotic use was the only significant correlate for household colonization (p = .002). Seventy-eight (24%) households reported serious skin infection. In contrast with colonization, five of the six risk factors that increased the risk of skin infection in the household at the univariate level remained independently significant in multivariable analysis: international travel, sports participation, surgery, antibiotic use and towel sharing. S. aureus colonization was not significantly associated with serious skin infection in any analysis. Among multiperson households with more than one person colonized, 50% carried the same strain.

Conclusions/Significance

The lack of association between S. aureus nasal colonization and serious skin infection underscores the need to explore alternative venues or body sites that may be crucial to transmission. Moreover, the magnitude of colonization and infection within the household suggests that households are an underappreciated and substantial community reservoir.

Prevalence and risk factors of nasal colonization with Staphylococcus aureus - association with HIV infection in older patients

Nasal S. aureus colonization was detected in 62/127 patients (49%) at a German infectious diseases clinic; MRSA colonization was infrequent at 2.4%. Male gender (OR=2.71, p=0.04), antimicrobial therapy in hospitalized patients (OR=20.1, p=0.02), and HIV infection in patients>42 y of age (OR=7.74, p=0.02) were independent risk factors for S. aureus colonization.

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization in HIV-infected ambulatory patients

BACKGROUND

Estimates of the prevalence of colonization with methicillin-resistant Staphylococcus aureus (MRSA) vary in HIV-infected patients.

METHODS

HIV clinic patients were prospectively cultured. Bilateral nasal and axillary swabs were plated on BBL CHROMagar MRSA media. Molecular typing was done by pulse-field gel electrophoresis, and staphylococcal cassette chromosomemec typing was determined. A patient questionnaire was conducted to ascertain potential MRSA risk factors; medical records were reviewed.

RESULTS

Fifteen of 146 (10.3%) patients had MRSA nasal colonization; 1 also had axillary colonization. Twelve of 15 isolates were staphylococcal cassette chromosomemec type IV, and 8 of 14 were USA300 or USA400 genotype. MRSA colonization was associated with lower CD4 cell count, not receiving current or recent antibiotics, history of prior MRSA or methicillin-susceptible Staphylococcus aureus infection (P < 0.05 for all), and a trend toward history of hospitalization or emergency department visit in the past year (P = 0.064). Current use of trimethoprim-sulfamethoxazole was protective for colonization: 0 of 29 trimethoprim-sulfamethoxazole recipients were colonized versus 15 of 117 nonrecipients, P = 0.04. In a multivariate logistic regression model, prior infection with either methicillin-susceptible S. aureus (odds ratio = 32.4, 95% confidence interval 3.04 to 345.42) or MRSA (odds ratio = 9.71, 95% confidence interval 2.20 to 43.01), not receiving current or recent antibiotics (odds ratio = 0.026, 95% confidence interval 0.002 to 0.412), and lower CD4 count (odds ratio 0.996, 95% confidence interval 0.992 to 0.999) were associated with MRSA colonization.

DISCUSSION

The prevalence of MRSA nasal colonization was relatively high compared with prior studies; axillary colonization was rare. Prior staphylococcal infection (methicillin-susceptible S. aureus or MRSA), not receiving antibiotics, and lower CD4 count were associated with MRSA nasal colonization. Trimethoprim-sulfamethoxazole seemed to be protective of MRSA colonization.

Community-associated methicillin-resistant Staphylococcus aureus infective endocarditis with Panton-Valentine leukocidin gene in an injection drug user with HIV infection

Reports of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates carrying Panton-Valentine leukocidin (PVL) gene that causes infective endocarditis in injection drug users (IDUs) with human immunodeficiency virus (HIV) infection are rare in the English language literature. We present a case of CA-MRSA infective endocarditis with bilateral septic lung emboli in a previously healthy 45-year-old IDU. This case suggests that PVL gene-positive CA-MRSA should be considered as a potential pathogen in IDUs with infective endocarditis.

Host-microbe interplay in persistent Staphylococcus aureus nasal carriage in HIV patients

It has been shown that persistent Staphylococcus aureus nasal carriage results in increased bacterial dispersal and a higher risk of infection compared to non-or-intermittent S. aureus carriage. Although many studies investigated S. aureus nasal carriage in HIV patients, none compared persistent carriage to non-persistent carriage nor were studies performed in the HAART era. We investigated the host-microbe interplay of persistent S. aureus nasal carriage in HIV-infected patients by studying host determinants of persistent carriage as well as the genetic structure of S. aureus strains isolated. We compared this genetic structure with the previously determined population structure of S. aureus isolates obtained from healthy individuals. Between February 2004 and June 2005 all HIV patients visiting the outpatient department of Erasmus MC (Rotterdam, The Netherlands) were asked to participate in this study. Participants were interviewed and screened for persistent S. aureus carriage using two semi-quantitative nasal swab cultures. For 443 patients two cultures were available, 131 (29.6%) were persistent carriers, which is significantly higher as compared to healthy individuals from the same geographic region (17.6%; P<0.0001). Male sex (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.32-3.73), current smoking (OR, 0.58; 95% CI, 0.38-0.90), Pneumocystis jiroveci pneumonia (PCP) prophylaxis (OR, 0.39; 95% CI, 0.16-0.97) and antiretroviral therapy (OR, 0.61; 95% CI, 0.38-0.98) were independent determinants of persistent carriage. Only two strains were mecA positive (1.2%) and no PVL positive strains were detected. The population structure of S. aureus strains isolated from HIV patients appeared to be strongly overlapping with that of S. aureus isolates from healthy individuals.