S. aureus nasal carriage among hemodialysis (HD) patients

Microbiology of Non-Tunnelled Catheter-Related Infections

INTRODUCTION

Aerobic bacterial infections often complicate vascular access in patients receiving haemodialysis, leading to Catheter-Related Blood Stream Infections (CRBSI). Various studies report Gram - positive bacteria, Staphylococcus aureus (S. aureus) in particular, as the most common aetiologic agent. Studies on microbiological analysis in this subset of population from India are very few.

AIM

To examine clinical and bacteriological profiles of haemodialysis patients developing CRBSI, the antibiotic susceptibility of the bacteria isolated from these patients and determine nasal carriage of S. aureus in the study subjects.

MATERIALS AND METHODS

Using a prospective observational design 127 patients receiving haemodialysis (84 males; 43 females) from October 2011 to March 2013 were enrolled in this study. At each dialysis session, catheters were examined for any evidence of infection. In case of suspicion for infection, pus swab, blood culture and the catheter tips were sent to microbiology laboratory for site specific investigations. Vancomycin injection was empirically administered to these patients pending culture results. Data obtained was examined for relationship of CRBSI with clinical and socio-demographic risk factors.

RESULTS

Out of 127 patients, 19 developed CRBSI, 10 developed exit-site infections and 33 patients were noted to have colonization of their catheters. The most common organisms included S. aureus in 24 (45.2%) catheter tips, followed by Pseudomonas aeruginosa in 9 (17%), Acinetobacter spp. in 5 (9%), Enterobacter spp. in 4 (7.5%) and Klebsiella pneumoniae in 3 (5.6%) catheter tips. Bacteraemia was found in 19 (20.7%) patients and P. aeruginosa was the most commonly isolated organism amongst them (38.8%). Staphylococcal nasal carriage was seen in 60 (69%) patients and 36 (41.4%) of these isolates were methicillin-resistant. Significant factors associated with CRBSI included history of bacteraemia, presence of diabetes mellitus, long duration (>15 days) of catheterization and antibiotic use within three months (p<0.05 for all).

CONCLUSION

Although S. aureus was the most common colonizer of non-tunnelled central access catheters among haemodialysis patients, CRBSI was most frequently caused by P. aeruginosa, which may have a bearing on our current antibiotic policy.

Meta-analysis of methicillin-resistant Staphylococcus aureus colonization and risk of infection in dialysis patients

Patients undergoing dialysis are particularly vulnerable to methicillin-resistant Staphylococcus aureus (MRSA) infections. We performed a meta-analysis of published studies to estimate the prevalence of MRSA colonization in dialysis patients, time trends, and long-term risk of subsequent MRSA infections. Our search of the PubMed and Embase databases returned 5743 nonduplicate citations, from which we identified 38 relevant studies that included data on 5596 dialysis patients. The estimated prevalence of MRSA colonization was 6.2% (95% confidence interval [95% CI], 4.2% to 8.5%). The prevalence increased over time but remained stable after 2000. Stratification of patients according to dialysis modality and setting revealed that 7.2% (95% CI, 4.9% to 9.9%) of patients on hemodialysis were colonized with MRSA compared with 1.3% (95% CI, 0.5% to 2.4%) of patients on peritoneal dialysis (P=0.01), and that a statistically significant difference existed in the percentage of colonized inpatients and outpatients (14.2% [95% CI, 8.0% to 21.8%] versus 5.4% [95% CI, 3.5% to 7.7%], respectively; P=0.04). Notably, the risk of developing MRSA infections increased among colonized hemodialysis patients compared with noncolonized patients (relative risk, 11.5 [95% CI, 4.7 to 28.0]). The long-term (6-20 months) probability of developing a MRSA infection was 19% among colonized hemodialysis patients compared with only 2% among noncolonized patients. In summary, 6.2% of dialysis patients are MRSA colonized, and the average prevalence of colonization has remained stable since 2000. Colonization in hemodialysis patients is associated with increased risk of MRSA infection.

Multidrug-resistant organisms in dialysis patients

Multidrug-resistant organisms (MDROs) have emerged as important causes of healthcare-associated infections (HAIs), and these infections are associated with significant morbidity and mortality. Dialysis patients have been particularly affected by these pathogens, with colonization and infection rates often exceeding those seen in persons with other types of healthcare exposure. The infection control practices that are currently recommended for use in dialysis facilities and other healthcare settings have the potential to eliminate, or at least substantially reduce transmission of and infection with MDROs. Unfortunately, recent data suggest that these recommended practices are not consistently implemented. Additional efforts and research are needed to increase healthcare workers' awareness of and adherence to infection prevention measures, to develop new and more effective prevention strategies, and to determine cost-effective approaches to MDRO prevention to optimize the safety and quality of care provided to dialysis patients.

Clinical and molecular epidemiology of methicillin-resistant Staphylococcus aureus among patients in an ambulatory hemodialysis center

OBJECTIVE

To describe the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) carriage and transmission in an ambulatory hemodialysis population.

DESIGN

Prospective cohort study.

SETTING

Outpatient hemodialysis facility affiliated with a large academic medical center.

PARTICIPANTS

Of the 170 facility patients, 103 (61%) participated in the study.

METHODS

Swab specimens of the nares, axillae, and vascular access site were collected from participants weekly for 3 weeks and then monthly for 5 months. Demographic and clinical data were collected monthly for 12 months. Molecular analysis of MRSA isolates was performed.

RESULTS

The baseline MRSA carriage prevalence was 12%. Factors associated with MRSA carriage included a history of MRSA; failed renal transplantation; hospital admission within 6 months; and receipt of a first-generation cephalosporin, cefepime, or vancomycin. Six subjects acquired MRSA after enrollment (incidence, 1.2 per 100 patient-months at-risk; overall prevalence, 18%). Molecular analysis suggested that transmission occurred within the facility. The incidence of MRSA infection among carriers was 1.76 per 100 patient-months. Community-associated strains (ie, USA300) were isolated from 28% of carriers and at least 25% of infections.

CONCLUSIONS

The prevalence of MRSA carriage and the incidence of infection among carriers were high among ambulatory hemodialysis patients, and community-associated MRSA was responsible for a large portion of the MRSA burden. A relatively high rate of MRSA acquisition was observed, with indirect evidence of intrafacility transmission. Additional studies are needed to confirm these findings and to identify effective and feasible methods to prevent MRSA transmission and infection among hemodialysis patients.