Decrease in the incidence of mupirocin resistance among methicillin-resistant Staphylococcus aureus in carriers from an intensive care unit

Staphylococcus aureus resistance to topical antimicrobials in atopic dermatitis

Background

Topical antimicrobial drugs are indicated for limited superficial pyodermitis treatment, although they are largely used as self-prescribed medication for a variety of inflammatory dermatoses, including atopic dermatitis. Monitoring bacterial susceptibility to these drugs is difficult, given the paucity of laboratory standardization.

Objective

To evaluate the prevalence of Staphylococcus aureus topical antimicrobial drug resistance in atopic dermatitis patients.

Methods

We conducted a cross-sectional study of children and adults diagnosed with atopic dermatitis and S. aureus colonization. We used miscellaneous literature reported breakpoints to define S. aureus resistance to mupirocin, fusidic acid, gentamicin, neomycin and bacitracin.

Results

A total of 91 patients were included and 100 S. aureus isolates were analyzed. All strains were methicillin-susceptible S. aureus. We found a low prevalence of mupirocin and fusidic acid resistance (1.1% and 5.9%, respectively), but high levels of neomycin and bacitracin resistance (42.6% and 100%, respectively). Fusidic acid resistance was associated with more severe atopic dermatitis, demonstrated by higher EASI scores (median 17.8 vs 5.7, p=.009). Our results also corroborate the literature on the absence of cross-resistance between the aminoglycosides neomycin and gentamicin.

Conclusions

Our data, in a southern Brazilian sample of AD patients, revealed a low prevalence of mupirocin and fusidic acid resistance of S. aureus atopic eczema colonizer strains. However, for neomycin and bacitracin, which are commonly used topical antimicrobial drugs in Brazil, high levels of resistance were identified. Further restrictions on the use of these antimicrobials seem necessary to keep resistance as low as possible.

Clinical Effectiveness of Mupirocin for Preventing Staphylococcus aureus Infections in Nonsurgical Settings: A Meta-analysis

A systematic literature review and meta-analysis was performed to identify effectiveness of mupirocin decolonization in prevention of Staphylococcus aureus infections, among nonsurgical settings. Of the 15 662 unique studies identified up to August 2015, 13 randomized controlled trials, 22 quasi-experimental studies, and 1 retrospective cohort study met the inclusion criteria. Studies were excluded if mupirocin was not used for decolonization, there was no control group, or the study was conducted in an outbreak setting. The crude risk ratios were pooled (cpRR) using a random-effects model. We observed substantial heterogeneity among included studies (I(2) = 80%). Mupirocin was observed to reduce the risk for S. aureus infections by 59% (cpRR, 0.41; 95% confidence interval [CI], .36-.48) and 40% (cpRR, 0.60; 95% CI, .46-.79) in both dialysis and nondialysis settings, respectively. Mupirocin decolonization was protective against S. aureus infections among both dialysis and adult intensive care patients. Future studies are needed in other settings such as long-term care and pediatrics.

Enteropathogenic bacteria contamination of unchlorinated drinking water in Korea, 2010

OBJECTIVES

The purpose of this study was to assess the microbiological quality of unchlorinated drinking water in Korea, 2010. One hundred and eighty unchlorinated drinking water samples were collected from various sites in Seoul and Gyeonggi province.

METHODS

To investigate bacterial presence, the pour plate method was used with cultures grown on selective media for total bacteria, total coliforms, and Staphylococcus spp., respectively.

RESULTS

In the 180 total bacteria investigation, 72 samples from Seoul and 33 samples from Gyeonggi province were of an unacceptable quality (>10(2) CFU/mL). Of all the samples tested, total coliforms were detected in 28 samples (15.6%) and Staphylococcus spp. in 12 samples (6.7%). Most of the coliform isolates exhibited high-level resistance to cefazolin (88.2%), cefonicid (64.7%) and ceftazidime (20.6%). In addition, Staphylococcus spp. isolates exhibited high-level resistance to mupirocin (42%). Species of Pseudomonas, Acinetobacter, Cupriavidus, Hafnia, Rahnella, Serratia, and Yersinia were isolated from the water samples.

CONCLUSIONS

The results of this study suggest that consumption of unchlorinated drinking water could represent a notable risk to the health of consumers. As such, there is need for continuous monitoring of these water sources and to establish standards.

Mupirocin resistance related to increasing mupirocin use in clinical isolates of methicillin-resistant Staphylococcus aureus in a pediatric population

We investigated the proportion of methicillin-resistant Staphylococcus aureus (MRSA) isolates from pediatric patients demonstrating mupirocin resistance related to mupirocin use at our institution. No mupirocin resistance was found in 98% of isolates, whereas mupirocin prescriptions increased by 110%. Resistance rates remained low despite the increasing use of mupirocin.

Phenotypic and molecular characterization of Staphylococcus aureus isolates expressing low- and high-level mupirocin resistance in Nigeria and South Africa

BACKGROUND

Mupirocin is a topical antimicrobial agent which is used for the treatment of skin and postoperative wound infections, and the prevention of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). However, the prevalence of mupirocin resistance in S. aureus, particularly in MRSA, has increased with the extensive and widespread use of this agent in hospital settings. This study characterized low- and high-level mupirocin-resistant S. aureus isolates obtained from Nigeria and South Africa.

METHODS

A total of 17 mupirocin-resistant S. aureus isolates obtained from two previous studies in Nigeria and South Africa, were characterized by antibiogram, PCR-RFLP of the coagulase gene and PFGE. High-level mupirocin resistant isolates were confirmed by PCR detection of the mupA gene. The genetic location of the resistance determinants was established by curing and transfer experiments.

RESULTS

All the low-level mupirocin resistant isolates were MRSA and resistant to gentamicin, tetracycline and trimethoprim. PFGE identified a major clone in two health care institutions located in Durban and a health care facility in Pietermaritzburg, Greytown and Empangeni. Curing and transfer experiments indicated that high-level mupirocin resistance was located on a 41.1 kb plasmid in the South African strain (A15). Furthermore, the transfer of high-level mupirocin resistance was demonstrated by the conjugative transfer of the 41.1 kb plasmid alone or with the co-transfer of a plasmid encoding resistance to cadmium. The size of the mupirocin-resistance encoding plasmid in the Nigerian strain (35 IBA) was approximately 35 kb.

CONCLUSION

The emergence of mupirocin-resistant S. aureus isolates in Nigeria and South Africa should be of great concern to medical personnel in these countries. It is recommended that methicillin-susceptible S. aureus (MSSA) and MRSA should be routinely tested for mupirocin resistance even in facilities where the agent is not administered. Urgent measures, including judicious use of mupirocin, need to be taken to prevent clonal dissemination of the mupirocin/methicillin resistant S. aureus in KZN, South Africa and the transfer of the conjugative plasmid encoding high-level mupirocin resistance identified in this study.

Trends in antibiotic susceptibility patterns and epidemiology of MRSA isolates from several hospitals in Riyadh, Saudi Arabia

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA), is associated with high morbidity and mortality rates with rapid development of resistance.

METHODS

A total of 512 MRSA isolates were procured from 6 major hospitals in Riyadh, Saudi Arabia and antibiotic susceptibilities and MICs were documented against several antibiotics and vancomycin. SPSS version 10 was used for statistical analysis.

RESULTS

The prevalence of MRSA in the study hospitals ranged from 12% to 49.4%. Mean patient age was 44 years with males constituting 64.4% and females 35.6%. Approximately 41.5% of the isolates came from patients in the extreme age groups. MIC for vancomycin was in the susceptible range for all isolates ranging from 0.25 to 3 ug/ml. The overall susceptibility of MRSA to the various antibiotics tested was: fusidic acid 4.3%, sulfamethoxazole/trimethoprim 33.8%, gentamicin 39.6%, mupirocin 77.0%, gatifloxacin 78.9%, chloramphenicl 80.7%, linezolid 95.1%, quinupristin/dalfopristin 100%. Some differences were noted in the resistance of isolates among the participating hospitals reflecting antibiotic usage. On the whole, inpatient isolates (accounting for 77.5% of the isolates) were more resistant than outpatient isolates (22.5%) except for linezolid. Quinupristin-dalfopristin and linezolid are the most effective antibiotics tested against inpatient isolates while quinupristin-dalfopristin and gatifloxacin seem to be the most effective against outpatient isolates. Approximately one forth of the isolates are no longer susceptible to mupirocin used for eradication of the carrier state reflecting resistance developing after widespread use. Trends over time show a tendency towards decreased susceptibility to gatifloxacin and linezolid with increasing susceptibility to gentamicin and sulfamethoxazole/trimethoprim.

CONCLUSION

Quinupristin/dalfopristin and linezolid are two valuable additions to our antimicrobial armamentarium, but resistance has already been described. To preserve their value, their use should be limited to those rare cases where they are clearly needed. Fusidic acid, the local antibiotic, gentamicin and trimethoprim/sulfamethoxazole should not be relied upon for treatment of MRSA infections, at least empirically as the percentage of susceptible isolates is very low.