Prevalence of high-level mupirocin resistance among meticillin-resistant Staphylococcus aureus isolates in a tertiary care hospital in Singapore

Mupirocin resistance in Staphylococcus aureus: A systematic review and meta-analysis

OBJECTIVES

Staphylococcus aureus is one of the most common pathogens causing nosocomial and community-acquired infections associated with high morbidity and mortality. Mupirocin has been increasingly used for treatment of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) infections. The aim of this study was to determine the prevalence of mupirocin-resistant S. aureus (MuRSA), mupirocin-resistant MRSA (MuRMRSA), high-level MuRSA (HLMuRSA) and high-level MuRMRSA (HLMuRMRSA) worldwide.

METHODS

Online databases including Medline, Embase and Web of Science were searched (2000-2018) to identify studies addressing the prevalence of MuRSA, MuRMRSA, HLMuRSA and HLMuRMRSA. STATA v. software was used to interpret the data.

RESULTS

Of the 2243 records identified from the databases, 30 and 63 studies fulfilled the eligibility criteria for MuRSA and MuRMRSA, respectively. Finally, 27 and 60 studies were included separately for HLMuRSA and HLMuRMRSA, respectively. The analyses revealed pooled and averaged prevalences of MuRSA, MuRMRSA, HLMuRSA and HLMuRMRSA of 7.6% [95% confidence interval (CI) 6.2-9.0%], 13.8% (95% CI 12.0-15.6%), 8.5% (95% CI 6.3-10.7%) and 8.1% (95% CI 6.8-9.4%), respectively.

CONCLUSION

Overall, these results show a global increase in the prevalence of HLMuRSA and HLMuRMRSA among clinical S. aureus isolates over time. However, there was only a significant increase in the prevalence of MuRMRSA compared with the other categories, especially MuRSA. Since mupirocin remains the most effective antibiotic for MSSA and MRSA decolonisation both in patients and healthcare personnel, a reduction of its effectiveness presents a risk for invasive infection. Monitoring of mupirocin resistance development remains critical.

Intranasal octenidine and universal antiseptic bathing reduce methicillin-resistant Staphylococcus aureus (MRSA) prevalence in extended care facilities

Intranasal octenidine, an antiseptic alternative to mupirocin, can be used for methicillin-resistant Staphylococcus aureus (MRSA) decolonisation in the prevention of nosocomial transmission. A controlled before-after study was conducted in three extended-care hospitals in Singapore. All inpatients with >48 h stay were screened for MRSA colonisation in mid-2015(pre-intervention) and mid-2016(post-intervention). Hospital A: universal daily chlorhexidine bathing throughout 2015 and 2016, with intranasal octenidine for MRSA-colonisers in 2016. Hospital B: universal daily octenidine bathing and intranasal octenidine for MRSA-colonisers in 2016. Hospital C: no intervention. In 2015, MRSA prevalence was similar among the hospitals (Hospital A: 38.5%, Hospital B: 48.1%, Hospital C: 43.4%, P = 0.288). From 2015 to 2016, MRSA prevalence reduced by 58% in Hospital A (Adj OR 0.42, 95% CI 0.20-0.89) and 43% in Hospital B (Adj OR 0.57, 95% CI 0.39-0.84), but remained similar in Hospital C (Adj OR 1.19, 95% CI 0.60-2.33), after adjusting for age, gender, comorbidities, prior MRSA carriage, prior antibiotics exposure and length of hospital stay. Compared with the change in MRSA prevalence from 2015 to 2016 in Hospital C, MRSA prevalence declined substantially in Hospital A (Adj OR 0.35, 95% CI 0.13-0.97) and Hospital B (Adj OR 0.48, 95% CI 0.22-1.03). Topical intranasal octenidine, coupled with universal daily antiseptic bathing, can reduce MRSA colonisation in extended-care facilities.

Infection Prevention Strategy in Hospitals in the Era of Community-Associated Methicillin-Resistant Staphylococcus aureus in the Asia-Pacific Region: A Review

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as an important cause of healthcare-associated infection. CA-MRSA clones have replaced classic hospital MRSA clones in many countries and have shown higher potential in transmission and virulence than hospital MRSA clones. In particular, the emergence of CA-MRSA in the Asia-Pacific region is concerning owing to insufficient infection control measures in the region. The old strategies for infection prevention and control of MRSA comprised adherence to standard precaution and policy of active screening of MRSA carriers and decolonization, and it has been controversial which strategy is better in terms of outcome and cost-effectiveness. Epidemiological changes in MRSA has made the development of infection prevention strategy more complicated. Based on the literature review and the questionnaire survey, we considered infection prevention strategies for healthcare settings in the Asia-Pacific region in the era of CA-MRSA.

Active Surveillance Cultures and Decolonization to Reduce Staphylococcus aureus Infections in the Neonatal Intensive Care Unit

BACKGROUND

Staphylococcus aureus is a common cause of healthcare-associated infections in neonates.

OBJECTIVE

To examine the impact of methicillin-susceptible S. aureus (MSSA) decolonization on the incidence of MSSA infection and to measure the prevalence of mupirocin resistance.

METHODS

We retrospectively identified neonates admitted to a tertiary care neonatal intensive care unit (NICU) from April 1, 2011, through September 30, 2014. We compared rates of MSSA-positive cultures and infections before and after implementation of an active surveillance culture and decolonization intervention for MSSA-colonized neonates. We used 2 measurements to identify the primary outcome, NICU-attributable MSSA: (1) any culture sent during routine clinical care that grew MSSA and (2) any culture that grew MSSA and met criteria of the National Healthcare Safety Network's healthcare-associated infection surveillance definitions. S. aureus isolates were tested for mupirocin susceptibility. We estimated incidence rate ratios using interrupted time-series models.

RESULTS

Before and after the intervention, 1,523 neonates (29,220 patient-days) and 1,195 neonates (22,045 patient-days) were admitted to the NICU, respectively. There was an immediate reduction in the mean quarterly incidence rate of NICU-attributable MSSA-positive clinical cultures of 64% (incidence rate ratio, 0.36 [95% CI, 0.19-0.70]) after implementation of the intervention, and MSSA-positive culture rates continued to decrease by 21% per quarter (incidence rate ratio, 0.79 [95% CI, 0.74-0.84]). MSSA infections also decreased by 73% immediately following the intervention implementation (incidence rate ratio, 0.27 [95% CI, 0.10-0.79]). No mupirocin resistance was detected.

CONCLUSION

Active surveillance cultures and decolonization may be effective in decreasing S. aureus infections in NICUs.

Clonal variation in high- and low-level phenotypic and genotypic mupirocin resistance of MRSA isolates in south-east London

OBJECTIVES

Both low-level mupirocin resistance (LMR) and high-level mupirocin resistance (HMR) have been identified. The aim of this study was to determine the epidemiology of LMR and HMR in MRSA isolates at five hospitals that have used mupirocin for targeted decolonization as part of successful institutional control programmes.

METHODS

All MRSA identified in three microbiology laboratories serving five central and south-east London hospitals and surrounding communities between November 2011 and February 2012 were included. HMR and LMR were determined by disc diffusion testing. WGS was used to derive multilocus sequence types (MLSTs) and the presence of HMR and LMR resistance determinants.

RESULTS

Prevalence of either HMR or LMR amongst first healthcare episode isolates from 795 identified patients was 9.69% (95% CI 7.72-11.96); LMR was 6.29% (95% CI 4.70-8.21) and HMR was 3.40% (95% CI 2.25-4.90). Mupirocin resistance was not significantly different in isolates identified from inpatients at each microbiology laboratory, but was more common in genotypically defined 'hospital' rather than 'community' isolates (OR 3.17, 95% CI 1.36-9.30, P = 0.002). LMR was associated with inpatient stay, previous history of MRSA and age ≥65 years; HMR was associated with age ≥65 years and residential postcode outside London. LMR and HMR varied by clone, with both being low in the dominant UK MRSA clone ST22 compared with ST8, ST36 and ST239/241 for LMR and with ST8 and ST36 for HMR. V588F mutation and mupA carriage had high specificity (>97%) and area under the curve (>83%) to discriminate phenotypic mupirocin resistance, but uncertainty around the sensitivity point estimate was large (95% CI 52.50%-94.44%). Mutations in or near the mupA gene were found in eight isolates that carried mupA but were not HMR.

CONCLUSIONS

Mupirocin resistance was identified in <10% of patients and varied significantly by clone, implying that changes in clonal epidemiology may have an important role in determining the prevalence of resistance in conjunction with selection due to mupirocin use.

Antiseptic Body Washes for Reducing the Transmission of Methicillin-Resistant Staphylococcus aureus: A Cluster Crossover Study

In a cluster cross-over trial, targeted decolonization with octenidine body washes was not associated with reduction in MRSA transmission or infection

Background. Limiting the spread of methicillin-resistant Staphylococcus aureus (MRSA) within healthcare facilities where the organism is highly endemic is a challenge. The use of topical antiseptic agents may help interrupt the transmission of MRSA and reduce the risk of clinical infection. Octenidine dihydrochloride is a topical antiseptic that exhibits in vitro efficacy against a wide variety of bacteria, including S aureus.

Methods. We conducted a prospective cluster crossover study to compare the use of daily octenidine body washes with soap and water in patients identified by active surveillance cultures to be MRSA-colonized, to prevent the acquisition of MRSA in patients with negative screening swabs. Five adult medical and surgical wards and 2 intensive care units were selected. The study involved an initial 6-month phase using octenidine or soap washes followed by a crossover in each ward to the alternative product. The primary and secondary outcomes were the rates of new MRSA acquisitions and MRSA clinical infections, respectively.

Results. A total of 10 936 patients admitted for ≥48 hours was included in the analysis. There was a small reduction in MRSA acquisition in the intervention group compared with controls (3.0% vs 3.3%), but this reduction was not significant (odds ratio, 0.89; 95% confidence interval, .72–1.11; P = .31). There were also no significant differences in clinical MRSA infection or incidence of MRSA bacteremia.

Conclusions. This study suggests that the targeted use of routine antiseptic washes may not in itself be adequate to reduce the transmission of MRSA in an endemic hospital setting.

Decolonization to prevent Staphylococcus aureus transmission and infections in the neonatal intensive care unit

Staphylococcus aureus (S. aureus) continues to be a leading cause of outbreaks and health-care-associated infections in neonatal intensive care units. In the first few months of life, many neonates acquire S. aureus as part of their delicate and evolving microbiota. Neonates that asymptomatically acquire S. aureus colonization are at increased risk of developing a subsequent S. aureus infection. This review discusses the epidemiology and prevention of S. aureus disease in neonates and how decolonization to eradicate S. aureus may decrease S. aureus transmission and infections in the neonatal intensive care unit.

Consensus statement on the management of methicillin-resistant Staphylococcus aureus nosocomial pneumonia in Asia

Nosocomial pneumonia (NP; encompassing hospital-acquired, health care-associated and ventilator-associated pneumonia) is one of the most common nosocomial infections and is associated with a mortality rate of 18.7%-40.8% in Asian countries. The burden of methicillin-resistant Staphylococcus aureus (MRSA) infections in Asia is high, and approximately 13% of NP cases in Asia are caused by this pathogen. Evidence regarding optimal management of MRSA NP continues to evolve and is complicated by the fact that a significant proportion of cases are likely to be caused by isolates with reduced susceptibility to the main therapeutic agent, vancomycin. The Asian Consensus Taskforce on MRSA Nosocomial Pneumonia has developed this statement to provide consensus points on diagnosis, antimicrobial treatment and prevention strategies for MRSA NP in the Asian context, based on our review of Asian data, previous international guidelines and recent scientific evidence.

Mupirocin susceptibility in Staphylococcus aureus nasal and oropharyngeal isolates from Brazilian children

Mupirocin is a topical antimicrobial agent and part of most Staphylococcus aureus decolonization regimens. Thus, knowing the mupirocin susceptibility profile of colonizing S. aureus is paramount for the proper use of this agent. We evaluated S. aureus isolates from 128 colonized children, using disc diffusion (with 5 mcg and 200 mcg discs) and Etest. None were low-level or high-level mupirocin-resistant. Since mupirocin will be increasingly needed for the control of S. aureus infection, continuous monitoring of its susceptibility status is necessary.

Changing molecular epidemiology and high rates of mupirocin resistance among meticillin-resistant Staphylococcus aureus in Singaporean hospitals

A prospective cross-sectional study was performed to determine the continuing shift in the molecular epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) in Singapore. In total, 666 MRSA isolates from screening cultures performed between 7 and 20 January 2013 were obtained from all seven public sector hospitals in Singapore and were subjected to molecular typing using multilocus variable-number tandem-repeat fingerprinting with confirmatory multilocus sequencing typing for clustered isolates. Isolates were also tested for the presence of the orfX-ACME insert and the high-level mupirocin resistance gene ileS-2. The major circulating clones in Singaporean hospitals were ST22 (63.2%), ST45 (18.9%) and ST239 (10.7%). The orfX-ACME insert was only found in ST239 isolates (31/71, 43.7%), but ileS-2 was found in 207 (31.1%) of the MRSA isolates, varying between 10.0% and 47.8% among the hospitals. In conclusion, the molecular epidemiology of MRSA in Singaporean hospitals has continued to change, with ST45 now replacing ST239 in addition to the ongoing replacement of the latter by ST22. Although a greater proportion of ST239 isolates carry the orfX-ACME insert, the actual clinical impact may be marginal as ST239 MRSA continues to decline. Finally, high-level mupirocin resistance rates are remarkably high in local healthcare-associated MRSA, with implications for MRSA decolonisation and infection prevention. Further surveillance is required to monitor the changing epidemiological trends.