High-level Mupirocin Resistance Research Articles

Prevention of Peritoneal Dialysis Catheter Infections in Saudi Peritoneal Dialysis Patients: The Emergence of High-Level Mupirocin Resistance

Exit-site infection (ESI) and peritonitis remain the major causes of morbidity and mortality in peritoneal dialysis (PD) patients. This study compared the effectiveness of local mupirocin ointment and gentamicin cream in preventing both gram-positive and gram-negative bacterial infections in PD patients. Patients from two centers (n = 203) were assigned to daily mupirocin ointment or gentamicin cream application. Infections were tracked prospectively by organisms and expressed as episodes per patient-year for both ESI and peritonitis. The rate of gram-positive ESI was 0.31/episode/patient-year and 0.22 episodes/patient-year (p<0.05), whereas the rate of gram-negative ESI was 0.28 episode/patient-year and 0.11 episode/patient-year (p<0.01) in the mupirocin group and gentamicin group, respectively. Gram-positive ESI occurred in 17.1% vs 10.2% of patients (p<0.05), whereas 20% of and 5.1% of patients (p<0.001) had gram-negative ESI in the 2 groups respectively. S.aureus was cultured at exit-site in the mupirocin group in 27.8% patients, 60% (16.7% of the total Gram-positive isolates) of them being with high-level mupirocin-resistance. Pseudomonas aeruginosa was cultured in 21.8% of ESI in the mupirocin group, and in only 6.7% in the gentamicin group (p<0.01). Peritonitis rates were lower using gentamicin cream, 0.17 episode/patient-year compared with mupirocin, 0.39 episode/patient-year (p<0.01). With multivariate analysis, only gentamicin exit-site use was a significant predictor for lower catheter infection rate. Prolonged use of mupirocin for ESI-prophylaxis is associated with the emergence of mupirocin-resistant S. aureus. Gentamicin cream is superior to mupirocin ointment in the prevention of PD catheter infections.

Molecular epidemiology of plasmid-mediated high-level mupirocin resistance in methicillin-resistant Staphylococcus aureus in four Spanish health care settings

Mupirocin is used for the decolonization of methicillin-resistant Staphylococcus aureus (MRSA). High-level mupirocin resistance (Hi-MupR) is of concern, having been associated with therapeutic failure. Our main objective was to assess the emergence and mode/s of spread of Hi-MupR in the MRSA population recovered between 2002 and 2009 in four health care settings in the Pontevedra province, northwest Spain. Five hundred and fifty consecutive clinical MRSA isolates were obtained and screened for antimicrobial susceptibility. Isolates were stratified into multidrug-resistant (MDR) and non-MDR. High-level mupirocin resistant MRSA were characterized by genotyping and plasmid analysis. Thirty-one MRSA (5.6%) exhibited Hi-MupR. No association was detected between Hi-MupR and MDR but isolates displaying Hi-MupR were more likely to be resistant to gentamicin and tobramycin. Four main MRSA clones were identified: ST125/t067/PFGE A, ST36/t018/PFGE D, ST8/t008/PFGE B, and ST72/t148 or t3092/PFGE B. Each isolate carried the Hi-MupRileS2-encoding gene on plasmids and ten plasmid types were distinguished based on unique IS257-ileS2 configurations. Some plasmid types were successfully disseminated among the MRSA clones. Remarkably, six plasmid types were acquired by the predominant genotype ST125/t067/PFGE A. In conclusion, molecular characterization of MRSA isolates combined with the rapid typing of ileS2-encoding plasmids through determination of IS257-ileS2 configurations have proved to be a powerful strategy to address the molecular epidemiology of Hi-MupR. The transmission of a diverse set of ileS2-carrying plasmids promoted the emergence of the resistance, with a limited role of clonal expansion in its dispersion.

The prevalence of methicillin resistant Staphylococcus aureus (MRSA) isolates with high-level mupirocin resistance from patients and personnel in a burn center

The rate of the MRSA strains, particularly at burn centers, is increasing worldwide. Detection of mupirocin resistance MRSA strains in the burn centers particularly from personnel will help to control these strains. For this purpose, a total of 116 Staphylococcus aureus isolates from the patients (burns) and personnel (nostrils) in Ahvaz Taleghani hospital (Iran) were investigated. The methicillin and mupirocin resistant isolates were detected by multiplex amplification of the mecA and ileS-2 genes. The mecA was found among 80% of isolates. The rates of mupirocin resistant strains among personnel and patients were 70% and 6%, respectively. The carriage rates of the S. aureus, MRSA and MRSA with high-level mupirocin resistance in the personnel were 40%, 34% and 28%, respectively. In conclusions, the high prevalence of MRSA strains in the patients showed the potential outbreak of the MRSA in the burn center and highlighted the need of antibiotic susceptibility monitoring of MRSA. Moreover being personnel as a main reservoir in terms of MRSA strains with high-level mupirocin resistance emphasizes the screening of the personnel in terms of the MRSA in the healthcare system especially in the burn center.

CPC-090 Mupirocin Resistant Meticillin-Resistant Staphylococcus Aureus (MRSA) – Do Patients Get the Correct Decolonisation After Screening?

BackgroundMRSA screening has been mandatory in England for two years. Mupirocin is used routinely for MRSA-positive patients but there is some resistance.Purpose A prospective audit was undertaken of all mupirocin-resistant...

Coexistence of mupirocin and antiseptic resistance in methicillin-resistant Staphylococcus aureus isolates from Korea

In this study, we determined the prevalence of mupirocin and antiseptics resistance in methicillin-resistant Staphylococcus aureus (MRSA) at a secondary- and a tertiary-care hospital in Korea. Mupirocin susceptibility test, ileS gene sequencing, and polymerase chain reaction for mupA, qacA/B, and smr gene were performed with 456 nonduplicated MRSA isolates collected from 2 hospitals in Korea. Genetic relatedness was determined by spa typing and multilocus sequence typing (MLST). The rates of low-level and high-level mupirocin resistance were 7% and 2% in the secondary-care hospital and 17% and 2% in the tertiary-care hospital, respectively. The positive rate of qacA/B and smr gene in mupirocin-resistant MRSA was 65% and 71%, respectively. In spa typing, most mupirocin-resistant MRSA showed genetic relatedness and some of the highly resistant isolates were ST239 and ST5 in MLST analysis. The distribution of low-level and high-level mupirocin resistance and the coexistence of antiseptic resistance in MRSA can result in failure of decolonization in Korea.

Meticillin-resistant Staphylococcus aureus in elderly residents of care homes: colonization rates and molecular epidemiology

Meticillin-resistant Staphylococcus aureus (MRSA) is a significant cause of mortality and morbidity in healthcare and community settings; however, there is a paucity of large-scale, longitudinal studies monitoring the occurrence of MRSA in the care home setting. To determine the molecular epidemiology of MRSA colonizing elderly residents of care homes. Residents in 65 care homes in Leeds, UK, were screened for MRSA nasal colonization in four consecutive years (2006-2009). Isolates were characterized using antibiotic susceptibility testing, detection of the Panton-Valentine leucocidin (PVL) locus, accessory gene regulator allotyping, characterization of the staphylococcal cassette chromosome mec element, spa-typing and pulsed-field gel electrophoresis. MRSA was recovered from 888 nasal swabs of 2492 residents and prevalence was similar (19-22%) throughout the study. Resistance to ≥3 antibiotic classes was common (34%), but resistance to only β-lactam agents was rare (3%); no PVL-positive isolates were identified. Most isolates were related to healthcare-associated epidemic-MRSA type 15 (EMRSA-15, ST22-IV); such isolates decreased in prevalence during the study (86-72%; P < 0.0001, χ(2)-test). The remainder belonged to five different multi-locus sequence type clonal complexes (CC). Most notably, CC59 strains increased in prevalence (10-25%; P < 0.0001, χ(2)-test) and were associated with high-level mupirocin resistance. The molecular epidemiology of MRSA in care homes is complex and dynamic. There was a high, consistent prevalence of MRSA nasal colonization, dominated by healthcare-associated strains. Vigilance is recommended; however, as high-level mupirocin resistance was associated with a single clonal group (CC59) that significantly increased in prevalence during the study.

Prevalence of High and Low Level Mupirocin Resistance among Staphylococcal Isolates from Skin Infection in a Tertiary Care Hospital.

Mupirocin has been used for the treatment of skin infections and for the eradication of the nasal carriage of Methicillin -resistant Staphylococcus aureus (MRSA). The increased use of this antibiotic has been accompanied by its resistance, resulting in treatment failures. This study was aimed at determining the prevalences of low and high level Mupirocin resistance among the clinical isolates of Staphylococcus species which were obtained from pyogenic infections. Clinical samples such as wound swabs, tissues and pus which were submitted to the microbiology laboratory during a period of six months were screened for the growth of Staphylococcus species, which were identified as Staphylococcus aureus and Coagulase negative Staphylococcus species by the routine microbiological procedures. All the isolates were tested for their Mupirocin susceptibilities by using 5 and 200 μg discs and their resistance was confirmed from their Minimum Inhibitory Concentrations (MICs). Out of 400 samples, 150 samples grew Staphylococcus species, of which 113 were Staphylococcus aureus and 37 were Coagulase negative Staphylococcus (CoNS). Only 5(3.3%) mupirocin resistant Staphylococcus species: three high level and two low level strains were detected. The MICs for the two low level and three high level Mupirocin resistant strains were 256 mg/L and ≥512mg/L each respectively. We conclude that the screening for mupirocin resistance, in terms of high-level and low-level resistance among the Staphylococcus species from patients with skin and soft tissue infections is warranted and that it is important for the clinicians in selecting the appropriate, empirical, topical, antimicrobial therapy. It also provides useful information about the prevalence of these resistant pathogens.

Mupirocin resistance in clinical isolates ofStaphylococcus aureusin a tertiary care hospital set up in North India

Background: Mupirocin is a topical antibiotic used for nasal decolonisation of methicillin resistant Staphylococcus aureus (MRSA). While resistance to mupirocin has been described it is usually not tested for in most clinical laboratories. Aim: The present study was carried out to detect the occurrence of mupirocin resistance in clinical isolates of Staphylococcus aureus in a tertiary care hospital set up in northern India. Materials and Methods: Staphylococcus aureus isolates obtained from clinical samples received in the microbiology laboratory over a period of one year were included in this study. Mupirocin resistance was detected by three phenotypic methods; disk diffusion method using 5μg and 200μg mupirocin disk to determine low-level and high-level resistance, broth microdilution method and an agar dilution method for determining minimum inhibitory concentrations. Methicillin sensitivity was also determined in the study isolates. Results: Of 250 non-duplicate Staphylococcus aureus isolates obtained, 5 (2%) were found resistant to mupirocin. All mupirocin resistance isolates were shown to have high-level resistance (minimum inhibitory concentration > 512μg/ml). All mupirocin resistant isolates were also resistant to methicillin. Results obtained by all three phenotypic methods showed good correlation. Conclusion: High-level mupirocin resistance is present in the northern Indian population which may be of major concern to prevent the spread of MRSA in hospitals and community.

Molecular characterization of high-level mupirocin resistance in Staphylococcus pseudintermedius.

The genetic analysis of high-level mupirocin resistance (Hi-Mup(r)) in a Staphylococcus pseudintermedius isolate from a dog is presented. The Hi-Mup(r) ileS2 gene flanked by a novel rearrangement of directly repeated insertion sequence IS257 elements was located, together with the aminoglycoside resistance aacA-aphD determinant, on a conjugative plasmid related to the pSK41/pGO1 family plasmids.

Chlorhexidine and Mupirocin Susceptibilities of Methicillin-Resistant Staphylococcus aureus from Colonized Nursing Home Residents

Chlorhexidine and mupirocin are used in health care facilities to eradicate methicillin-resistant Staphylococcus aureus (MRSA) carriage. The objective of this study was to assess the frequency of chlorhexidine and mupirocin resistance in isolates from nares carriers in multiple nursing homes and to examine characteristics associated with resistance. Nasal swab samples were collected from approximately 100 new admissions and 100 current residents in 26 nursing homes in Orange County, CA, from October 2008 to May 2011. MRSA isolates were tested for susceptibility by using broth microdilution, disk diffusion, and Etest; for genetic relatedness using pulsed-field gel electrophoresis; and for qac gene carriage by PCR. Characteristics of the nursing homes and their residents were collected from the Medicare Minimum Data Set and Long-Term Care Focus. A total of 829 MRSA isolates were obtained from swabbing 3,806 residents in 26 nursing homes. All isolates had a chlorhexidine MIC of ≤4 μg/ml. Five (0.6%) isolates harbored the qacA and/or qacB gene loci. Mupirocin resistance was identified in 101 (12%) isolates, with 78 (9%) isolates exhibiting high-level mupirocin resistance (HLMR). HLMR rates per facility ranged from 0 to 31%. None of the isolates with HLMR displayed qacA or qacB, while two isolates carried qacA and exhibited low-level mupirocin resistance. Detection of HLMR was associated with having a multidrug-resistant MRSA isolate (odds ratio [OR], 2.69; P = 0.004), a history of MRSA (OR, 2.34; P < 0.001), and dependency in activities of daily living (OR, 1.25; P = 0.004). In some facilities, HLMR was found in nearly one-third of MRSA isolates. These findings may have implications for the increasingly widespread practice of MRSA decolonization using intranasal mupirocin.

Mupirocin and Chlorhexidine Resistance in Staphylococcus aureus in Patients with Community-Onset Skin and Soft Tissue Infections

Decolonization measures, including mupirocin and chlorhexidine, are often prescribed to prevent Staphylococcus aureus skin and soft tissue infections (SSTI). The objective of this study was to determine the prevalence of high-level mupirocin and chlorhexidine resistance in S. aureus strains recovered from patients with SSTI before and after mupirocin and chlorhexidine administration and to determine whether carriage of a mupirocin- or chlorhexidine-resistant strain at baseline precluded S. aureus eradication. We recruited 1,089 patients with community-onset SSTI with or without S. aureus colonization. In addition to routine care, 483 patients were enrolled in a decolonization trial: 408 received intranasal mupirocin (with or without antimicrobial baths), and 258 performed chlorhexidine body washes. Patients were followed for up to 12 months with repeat colonization cultures. All S. aureus isolates were tested for high-level mupirocin and chlorhexidine resistance. At baseline, 23/1,089 (2.1%) patients carried a mupirocin-resistant S. aureus strain and 10/1,089 (0.9%) patients carried chlorhexidine-resistant S. aureus. Of 4 patients prescribed mupirocin, who carried a mupirocin-resistant S. aureus strain at baseline, 100% remained colonized at 1 month compared to 44% of the 324 patients without mupirocin resistance at baseline (P = 0.041). Of 2 patients prescribed chlorhexidine, who carried a chlorhexidine-resistant S. aureus strain at baseline, 50% remained colonized at 1 month compared to 48% of the 209 patients without chlorhexidine resistance at baseline (P = 1.0). The overall prevalence of mupirocin and chlorhexidine resistance is low in S. aureus isolates recovered from outpatients, but eradication efforts were less successful in patients carrying a mupirocin-resistant S. aureus strain at baseline.

274 Colonization of Methicillin-Resistant Staphylococcus Aureus With High-Level Resistance To Mupirocin In Korean Children

Increased mupirocin use has been considered as a major cause to develop mupirocin resistance among MRSA isolates. High-level mupirocin resistance (HLMR) is associated with decolonization failure, but fortunately most MRSA...

Emergence of Methicillin-Resistant Staphylococcus aureus ST239 with High-Level Mupirocin and Inducible Clindamycin Resistance in a Tertiary Care Center in Chennai, South India

Methicillin-resistant Staphylococcus aureus (MRSA) ST239 is probably the most predominant clone of MRSA causing hospital-acquired infections ([4][1]). Different clones of MRSA ST239 have been reported: Hungarian, Brazilian, Portuguese, and Viennese clones ([4][1]). MRSA ST239 is an invasive clone of

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

High-level resistance to mupirocin in meticillin-resistant Staphylococcus aureus (MRSA) jeopardizes its role in nasal decolonization protocols. We carried out a study in 2010 to determine the prevalence of high-level mupirocin resistance in our tertiary-care hospital. The prevalence of high-level resistance to mupirocin in MRSA in this hospital was 11%. There was also complete agreement between the genotypic and phenotypic methods of detection of high-level mupirocin resistance in 24 of the screening isolates.

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus Isolates from Patients Newly Identified as Nasal Carriers

We aimed to determine whether additional molecular and microbiological evaluations of methicillin-resistant Staphylococcus aureus (MRSA) isolated from patients newly identified as nasal carriers were useful for control strategies and whether longitudinal testing during the same or repeat hospitalization changed MRSA status. Nasal swabs from patients positive by Xpert MRSA PCR and not known to be colonized in the previous year were cultured for S. aureus. Isolates were tested for resistance to a variety of antibiotics, including high-level mupirocin resistance (HLMR) and low-level mupirocin resistance (LLMR) and the presence of genes mecA and mupA and those for Panton-Valentine leukocidin (PVL), USA300, and USA400. Repeat nasal screens during the 6-month study were tested for continued presence of MRSA. Among 130 patients, cultures revealed MRSA in 85 (65.4%), methicillin-susceptible S. aureus in 19 (14.6%), and no growth in 26 (20%). MRSA isolates were USA300 positive in 13/85 (15.3%) and LLMR in 8/85 (9.4%) patients. No isolates were HLMR or mupA positive. mecA dropout was detected in 9/130 (6.9%) patients. The rate of subsequent MRSA infections in USA300-positive versus -negative patients was not different. MRSA nasal status remained concordant in 69/70 (98.6%) patients who had follow-up testing. The findings do not support expanding MRSA surveillance to include routine detection of genes for USA300, PVL, or mupA, all of which were either of low frequency or not significantly associated with MRSA infection risk in our population of newly identified nasal carriers. Repeat nasal screening for MRSA during the same or subsequent hospitalizations over 6 months could also be deferred, reducing costs associated with screening.

Emergence of High-Level Mupirocin Resistance in Coagulase-Negative Staphylococci Associated with Increased Short-Term Mupirocin Use

In our hospital, mupirocin has increasingly been used for peri-operative decolonization of Staphylococcus aureus. The target for mupirocin is isoleucyl tRNA synthetase (ileS). High-level resistance to mupirocin is conferred by acquisition of plasmids expressing a distinct ileS gene (ileS2). Here we evaluated the longitudinal trends in high-level mupirocin resistance in coagulase-negative staphylococci (CoNS) and linked this to the presence of ileS2 genes and mupirocin use. We assessed mupirocin resistance in CoNS bloodstream isolates from 2006 to 2011 tested by Phoenix automated testing (PAT). We evaluated the reliability of PAT results using Etest. PAT species determination was confirmed by MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) mass spectrometry. We investigated the presence of ileS2 in the first 100 consecutive CoNS bloodstream isolates of each year using RT-PCR. Mupirocin use increased from 3.6 kg/year in 2006 to 13.3 kg/year in 2010 and correlated with the increase in the percentage of CoNS isolates carrying ileS2 (8% in 2006 to 22% in 2011; Spearman's rho, 0.137; P = 0.01). The sensitivity and specificity of PAT for detecting high-level mupirocin resistance were 0.97 and 0.97, respectively. ileS2 was detected in 81 of 82 phenotypically highly mupirocin-resistant strains and associated with resistance to ciprofloxacin, erythromycin, and clindamycin. In conclusion, we found a rapid increase in high-level resistance to mupirocin and resistance to other antibiotics in CoNS associated with an increase in mupirocin use. The associated resistance to other antibiotics may result in a reduction of oral antibiotic options for prolonged treatment of prosthetic infections with CoNS.

The prevalence of nasal carriage of meticillin resistant Staphylococcus aureus among healthcare workers in a non-acute healthcare facility

There is a lack of data available concerning the baseline prevalence of meticillin resistant Staphylococcus aureus (MRSA) carriage among healthcare workers (HCWs) in the Republic of Ireland. This anonymous prevalence study screened HCWs for nasal carriage of MRSA in a non-acute healthcare facility (HCF) in Dublin and the prevalence rate among these HCWs was calculated. Three hundred and four HCWs were invited to participate, with 112 (37%) consenting to take part in the study. Nasal swabs were analysed by culture method for MRSA with reference to Health Protection Agency guidelines. Meticillin resistant isolates were examined for presence of MecA gene by real-time polymerase chain reaction. The overall rate of nasal carriage MRSA was found to be 8.9% (10/112), of whom eight were nurses, one was medical staff and one was household/catering staff. High-level mupirocin resistance was detected in two of the isolates. This study confirms a significant prevalence of MRSA carriage among the cohort studied, particularly among frontline HCWs. This emphasises the need for strict adherence to infection control protocols to minimise healthcare associated MRSA infections among patients in non-acute healthcare facilities. The detection of high level mupirocin resistant MRSA has implications for MRSA decontamination protocols.

Resurgence of high-level mupirocin resistance in methicillin-resistant Staphylococcus aureus in Kuwait hospitals

Resurgence of high-level mupirocin resistance in methicillin-resistant Staphylococcus aureus in Kuwait hospitals

MupB, a New High-Level Mupirocin Resistance Mechanism in Staphylococcus aureus

Mupirocin is a topical antibiotic used for the treatment of skin infections and the eradication of methicillin-resistant Staphylococcus aureus carriage. It inhibits bacterial protein synthesis by interfering with isoleucyl-tRNA synthetase activity. High-level mupirocin resistance (MIC of ≥ 512 μg/ml) is mediated by the expression of mupA (ileS2), which encodes an alternate isoleucyl-tRNA synthetase. In this study, we describe high-level mupirocin resistance mediated by a novel locus, mupB. The mupB gene (3,102 bp) shares 65.5% sequence identity with mupA but only 45.5% identity with ileS. The deduced MupB protein shares 58.1% identity (72.3% similarity) and 25.4% identity (41.8% similarity) with MupA and IleS, respectively. Despite this limited homology, MupB contains conserved motifs found in class I tRNA synthetases. Attempts to transfer high-level mupirocin resistance via conjugation or transformation (using plasmid extracts from an mupB-containing strain) were unsuccessful. However, by cloning the mupB gene into a shuttle vector, it was possible to transfer the resistance phenotype to susceptible S. aureus by electroporation, proving that mupB was responsible for the high-level mupirocin resistance. Further studies need to be done to determine the prevalence of mupB and to understand risk factors and outcomes associated with resistance mediated by this gene.

The Prevalence, Genotype and Antimicrobial Susceptibility of High- and Low-Level Mupirocin Resistant Methicillin-ResistantStaphylococcus aureus

BackgroundMupirocin has been used for the treatment of skin infections and eradication of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). The increased use of this antibiotic has been accompanied by outbreaks of MRSA that are resistant to mupirocin.ObjectiveThis study aims to determine the prevalence, genotype and antimicrobial susceptibility of mupirocin-resistant MRSA from 4 Korean hospitals.MethodsA total 193 MRSA clinical isolates were collected from four university hospitals. Antimicrobial susceptibility tests, including mupirocin, and pulsed-field gel electrophoresis (PFGE) pattern analysis were performed.ResultsOverall, 27 of the 193 (14.1%) MRSA isolates were resistant to mupirocin. All of the (A) hospital isolates showed high-level (HL) mupirocin resistance and the low-level (LL) mupirocin resistant strains were from three other hospitals. The PFGE patterns of 16 mupirocin-resistant isolates were divided into 5 clusters (1-5), and the nine HL mupirocin-resistant isolates belonged to cluster 1. Both the HL and LL mupirocin-resistant MRSA isolates were susceptible to vancomycin and rifampin, but they were resistant to ciprofloxacin, clindamycin and tetracycline. The erythromycin and fusidic acid resistance rates were different between the HL and LL resistant isolates.ConclusionHL mupirocin-resistant isolates that could transfer this resistance to other bacteria were detected and these isolates were clonally related. The emergence of mupirocin resistant isolates emphasizes the importance of using antibiotics judiciously and carefully monitoring the prevalence of mupirocin resistance.