Effect of mupirocin for Staphylococcus aureus decolonization on the microbiome of the nose and throat in community and nursing home dwelling adults

Objective

To characterize the microbial communities of the anterior nares (nose) and posterior pharynx (throat) of adults dwelling in the community and in nursing homes before and after treatment with intranasal mupirocin.

Methods

Staphylococcus aureus-colonized adults were recruited from the community (n = 25) and from nursing homes (n = 7). S. aureus colonization was confirmed using cultures. Participants had specimens taken from nose and throat for S. aureus quantitation using quantitative PCR for the nuc gene and bacterial profiling using 16S rRNA gene sequencing over 12 weeks. After two baseline study visits 4 weeks apart, participants received intranasal mupirocin for 5 days with 3 further visits over a 8 week follow-up period.

Results

We found a decrease in the absolute abundance of S. aureus in the nose for 8 weeks after mupirocin (1693 vs 141 fg/ul, p = 0.047). Mupirocin caused a statistically significant disruption in bacterial communities of the nose and throat after 1 week, which was no longer detected after 8 weeks. Bacterial community profiling demonstrated that there was a decrease in the relative abundance of S. aureus (8% vs 0.3%, p<0.01) 8 weeks after mupirocin and a transient decrease in the relative abundance of Staphylococcus epidermidis in the nose (21% vs 5%, p<0.01) 1 week after mupirocin.

Conclusions

Decolonization with mupirocin leads to a sustained effect on absolute and relative abundance of S. aureus but not for other bacteria in the nose. This demonstrates that a short course of mupirocin selectively decreases S. aureus in the nose for up to 8 weeks.

Estimated Methicillin-Resistant Staphylococcus aureus Decolonization in Intensive Care Units Associated With Single-Application Chlorhexidine Gluconate or Mupirocin

IMPORTANCE

Chlorhexidine gluconate (CHG) and mupirocin are widely used to decolonize patients with methicillin-resistant Staphylococcus aureus (MRSA) and reduce risks associated with infection in hospitalized populations. Quantifying the association of an application of CHG alone or in combination with mupirocin with risk of MRSA infection is important for studies evaluating alternative decolonization strategies or schedules and for identifying whether there is room for improved decolonizing agents.

OBJECTIVE

To estimate the proportion of patients with MRSA decolonized per application of CHG and mupirocin from existing population-level studies.

DESIGN, SETTING, AND PARTICIPANTS

A stochastic mathematical model of an 18-bed intensive care unit (ICU) in an academic medical center operating over 1 year was used to estimate parameters for the proportion of simulated patients with MRSA decolonized per application of CHG and mupirocin. The model was conducted using approximate bayesian computation with data from an existing meta-analysis of studies conducted from February 2005 through January 2015. Data were analyzed from January 2018 through November 2019.

EXPOSURE

A universal decolonization protocol for colonized patients in the ICU using CHG or CHG and mupirocin in combination was simulated.

MAIN OUTCOMES AND MEASURES

The proportion of patients with MRSA decolonized per application of CHG and mupirocin was estimated.

RESULTS

The estimated proportion of patients with MRSA decolonized per application of CHG was 0.15 (95% credible interval, 0.01-0.42), and the estimated proportion per application of mupirocin in conjunction with CHG was 0.15 (95% credible interval, 0.01-0.54). A lag in colonization detection was associated with decreases in the CHG estimate (0.11; 95% credible interval, 0.01-0.30) and mupirocin estimate (0.10; 95% credible interval, 0.00-0.34), which were sensitive to the value of the modeled contact rate between nurses and patients. A 1% increase in the value of this parameter was associated with a 0.73% increase in the estimated combined outcomes associated with CHG and mupirocin (95% CI: 0.71, 0.75). Gaps longer than 24 hours in the administration of decolonizing agents were associated with a decrease of within-ICU MRSA transmission. Compared with a mean (SD) of 1.23 (0.27) acquisitions per 1000 patient-days in scenarios with no decolonizing bathing, a bathing protocol administering CHG and mupirocin every 120 hours was associated with a mean (SD) acquisition rate of 1.03 (0.24) acquisitions per 1000 patient days, a 16.3% decrease (95% CI, 14.7%-18.0%; P > .001).

CONCLUSIONS AND RELEVANCE

These findings suggest that there may be room for significant improvement in anti-MRSA disinfectants, including the compounds themselves and their delivery mechanisms. Despite the decolonization estimates found in this study, these agents are associated with robust outcomes after delays in administration, which may help in alleviating concerns over patient comfort and toxic effects.

Do Antimicrobial Resistance Patterns Matter? An Algorithm for the Treatment of Patients With Impetigo

BACKGROUND

Impetigo, a highly contagious bacterial skin infection commonly occurring in young children, but adults may also be affected. The superficial skin infection is mainly caused by Staphylococcus aureus (S. aureus) and less frequently by Streptococcus pyogenes (S. pyogenes). Antimicrobial resistance has become a worldwide concern and needs to be addressed when selecting treatment for impetigo patients. An evidence-based impetigo treatment algorithm was developed to address the treatment of impetigo for pediatric and adult populations.

METHODS

An international panel of pediatric dermatologists, dermatologists, pediatricians, and pediatric infectious disease specialists employed a modified Delphi technique to develop the impetigo treatment algorithm. Treatment recommendations were evidence-based, taking into account antimicrobial stewardship and the increasing resistance to oral and topical antibiotics.

RESULTS

The algorithm includes education and prevention of impetigo, diagnosis and classification, treatment measures, and follow-up and distinguishes between localized and widespread or epidemic outbreaks of impetigo. The panel adopted the definition of localized impetigo of fewer than ten lesions and smaller than 36 cm2 area affected in patients of two months and up with no compromised immune status. Resistance to oral and topical antibiotics prescribed for the treatment of impetigo such as mupirocin, retapamulin, fusidic acid, have been widely reported.

CONCLUSIONS

When prescribing antibiotics, it is essential to know the local trends in antibiotic resistance. Ozenoxacin cream 1% is highly effective against S. pyogenes and S. aureus, including methycyllin-susceptible and resistant strains (MRSA), and may be a suitable option for localized impetigo.J Drugs Dermatol. 2021;20(2):134-142. doi:10.36849/JDD.5475 THIS ARTICLE HAD BEEN MADE AVAILABLE FREE OF CHARGE. PLEASE SCROLL DOWN TO ACCESS THE FULL TEXT OF THIS ARTICLE WITHOUT LOGGING IN. NO PURCHASE NECESSARY. PLEASE CONTACT THE PUBLISHER WITH ANY QUESTIONS.

Mupirocin and Chlorhexidine Genotypic Resistance Found in Staphylococcus aureus Isolated From Young Infants Below 90 Days Old: A Genetic Basis for Eradication Failure

OBJECTIVES

To investigate the genetic characteristics associated with eradication failure of Staphylococcus aureus in infants below 90 days old.

METHODS

S. aureus isolated from clinical specimen cultures (blood, surgical tissue, or drainage, pus, etc.) and routine screening cultures in the neonatal intensive care unit (nasal and axillary skin swab) from patients below 90 days old were collected prospectively for 1 year, from August 2017 to July 2018. The isolates underwent typing and screening for genes associated with chlorhexidine (qacA/B), quaternary ammonium (smr), and mupirocin resistance (iles mutation, mupA, mupB), as well as Panton-Valentine leukocidin (PVL) toxin.

RESULTS

During the study period, 40 nonduplicate isolates were included for analyses, of which 70.0% were methicillin-resistant S. aureus (MRSA). Mupirocin resistance was found in 25% of the total isolates; 17.4% of the colonizers; and 35.3% of the pathogens (P = 0.196). Chlorhexidine resistance gene was found in 3 MRSA isolates colonized in the nares of preterm infants. All isolates harbored the disinfectant quaternary ammonium compound (QAC) resistance gene. PVL toxin gene was found in 57.5%, and the presence of PVL gene among colonizers and pathogens was similar (69.6% vs. 41.2%, P = 0.072).

CONCLUSIONS

Mupirocin, chlorhexidine, and QAC-resistant MRSAs harboring the PVL toxin gene were found in the nasal carriages of preterm infants. In this highly vulnerable patient population, one-fourth of the isolates harbored mupirocin-resistant genes, and all were resistant to QAC disinfectants. These strains are associated with persistence in both carriage and environmental reservoirs within the hospitals.

Impact of formulary interventions on the minimum inhibitory concentration of methicillin-resistant Staphylococcus aureus to mupirocin, chlorhexidine, and octenidine in a Singapore tertiary institution

Methicillin-resistant Staphylococcus aureus (MRSA) decolonization is an effective measure to prevent clinical infection but resistance is a concern. We aim to evaluate the impact of mupirocin (MUP) ointment formulary removal, plateauing use of chlorhexidine gluconate (CHG), and hospital-wide introduction of octenidine (OCT)-based products on the minimum inhibitory concentration (MIC) of MRSA to MUP, CHG, and OCT in our hospital. A prevalence study was conducted at three time points (TP) on consecutive MRSA screening isolates to evaluate for their MICs to MUP, CHG, and OCT using broth microdilution sensititre plates and detection of the ileS-2 gene encoding high-level MUP resistance in 2013 (pre-intervention TP1; n = 160), 2016 (early post-intervention TP2; n = 99) and 2017 (late post-intervention TP3; n = 76). Statistical analyses were performed using Chi square test with reference from TP1. There was a significant improvement in MUP susceptibility (MIC < 4 mcg/ml) from 71.9% (TP1) to 86.9% (TP2; p = 0.006) to 88.2% (TP3; p = 0.007). The prevalence of MUP high-level resistance (MIC > 256 mcg/ml) reduced from 25.0% (TP1) to 12.1% (TP2; p = 0.014) to 5.3% (TP3; p = 0.001). Likewise, the prevalence of isolates harboring the ileS-2 gene decreased from 28.1% (TP1) to 18.2% (TP2; p = 0.072) to 9.2% (TP3; p = 0.002). OCT MIC range remains stable at 0.5 to 1 mcg/ml across all three TPs. The proportion of isolates with reduced CHG susceptibility (MIC ≥ 4 mcg/ml) increased over the three TPs from 23.1 to 27.2% (p = 0.45) to 42.1% (p = 0.003). Active formulary regulations have an impact on the resistance profile of MRSA and can be used as a strategy to preserve the MRSA decolonization armamentarium.

Topical co-administration of Teucrium polium hydroethanolic extract and Aloe vera gel triggered wound healing by accelerating cell proliferation in diabetic mouse model

Diabetic wounds are major issues in patients with diabetes. Medicinal plants of Teucrium polium and Aloe vera have antioxidant and anti-inflammatory properties that may be profitable for diabetic patients. This study was conducted to evaluate the effect of co-administration of ointments prepared from Teucrium polium hydroethanolic extract (TPEO) and Aloe vera gel (AVGO) on excisional wound healing in a diabetic mouse model. Following the induction of diabetes and circular excisional wound (7 mm), the mice were divided into six groups, namely (Ⅰ) control mice treated with mupirocin (as a standard drug), (Ⅱ and Ⅲ) the mice treated with 5 and 10 % TPEO, (Ⅳ and Ⅴ) the mice treated with 5 and 10 % AVGO, and (Ⅵ) the mice treated with a combination of 5% TPEO and 5% AVGO (TPEO+AVGO). To investigate the wound area, we further evaluated the wound area ratio, histological analysis and the serum levels of tissue antioxidant capacity (TAC) and malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), immunohistochemistry staining for vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-1), glucose transporter-1(GLUT-1) and collagen type 1 and mRNA expression levels for VEGF, IGF-1, GLUT-1 and fibroblast growth factor-2 (FGF-2). The results showed that administration of the ointments, especially in combination form, shortened the inflammatory phase and reduced the levels of tissue MDA, TNF-α and IL-1β compared to mupirocin group (P < 0.05). Moreover, fibroblasts proliferation, collagen deposition, VEGF, IGF-1, GLUT-1-positive cells and level of TAC, and expressions of VEGF, IGF-1, GLUT-1 and FGF-2 were significantly (P < 0.05) increased in TPEO and AVGO, and especially in the mice treated with the mixed form. Therefore, topical co-administration of TPEO + AVGO accelerated open diabetic wound healing through shortening the inflammatory phase and increasing cell proliferation and collagen deposition.

The Clinical Utility of Analysis High Resolution Melting Curve Assay for Simultaneous Identification of Methicillin and Mupirocin Resistant in Coagulase-Negative Staphylococci

BACKGROUND

Resistance to methicillin and mupirocin in coagulase-negative staphylococci (CoNS) is considered as one of the most important issues. Meanwhile, use of phenotypic methods in detecting the resistance to methicillin and mupirocin has a lower accuracy and speed compared to other molecular methods, such as High-Resolution Melting Analysis (HRM). In this study, HRM technique was used to identify CoNS resistance stains.

METHODS

This experimental study was done on 86 isolates of CoNS strains isolated at Hamadan Hospital. Pheno-typic tests were used to identify Staphylococcus saprophyticus and S. epidermidis. Methicillin and Mupirocin resistant strains were tested using the MIC and HRM methods, and sensitivity and specificity of the primers were determined based on melting curve temperature range. In addition, data was analyzed by Applied Biosystems StepOne v 2.3 and Applied Biosystems HRM v 3.0.1 software.

RESULTS

Eighty-six (86) coagulase-negative isolates were isolated from different clinical specimens. Among these, 69 isolates of S. epidermidis and 17 isolates of S. saprophyticus were identified. Of the 69 S. epidermidis isolates, 19 isolates with oxacillin MIC ≥ 0.5 µg/mL and methicillin-resistant, and 11 isolates with mupirocin MIC ≥ 32 µg/mL and resistant to mupirocin. Of the 17 S. saprophyticus isolates, three isolates with oxacillin MIC ≥ 0.5 µg/mL were also methicillin-resistant, and one isolate with mupirocin MIC ≥ 32 µg/mL was resistant to mupirocin. Melting curve analysis for mecA and mupA primers was determined 81.7 ± 0.5°C and 74 ± 0.5°C, respectively. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of HRM assay for detection of methicillin and mupirocin strains testing were 100%.

CONCLUSIONS

Identification of methicillin and mupirocin resistance in CoNSs using the HRM method has high sensitivity and specificity. Molecular methods are more accurate and faster than phenotypic methods and can identify a large number of resistant isolates in a short time.

Prevalence of mupirocin and chlorhexidine resistance among methicillin-resistant coagulase-negative staphylococci isolated during methicillin-resistant Staphylococcus aureus decolonization strategies

BACKGROUND

The widespread of methicillin-resistant Staphylococcus aureus (MRSA) antimicrobial decolonization in the clinical setting may lead to an increase in the prevalence of multiresistance to coagulase-negative staphylococci (CoNS) owing to their selection. This study aimed to investigate the impact of MRSA decolonization strategies, using mupirocin and chlorhexidine, on their CoNS susceptibility.

METHODS

A total of 312 CoNS isolates were collected before starting the decolonization protocols "baseline strains" (BLS) group, 330 isolates were collected after application of the targeted decolonization protocol "targeted decolonization strains" group, and 355 isolates were collected after application of the universal decolonization protocol "universal decolonization strains" group. Methicillin-resistant CoNS (MR-CoNS) were identified and tested for mupirocin and chlorhexidine susceptibilities. Heptaplex polymerase chain reaction assay was applied for simultaneous screening for chlorhexidine (CHX-R) and mupirocin resistance (Mu-R) genes.

RESULTS

Mu-R prevalence of MR-CoNS among the BLS group was considered moderate (9.1%); however, CHX-R in the BLS group was 5.8%, the rate of which significantly increased among the universal decolonization strains group.

DISCUSSION

Both MRSA decolonization strategies have an additional benefit in reducing the prevalence of MR-CoNS. The prevalence Mu-R rate didn't change significantly during either of the MRSA decolonization practices that may be due to the local nature of mupirocin application on the nasal mucosa only. In contrast CHX-R that was found to be significantly higher among the UDS group.

CONCLUSIONS

Our findings indicate that both MRSA decolonization strategies have an additional benefit in reducing the prevalence of MR-CoNS. Although the universal MRSA decolonization has superior efficacy in decolonization of CoNS, it may increase the risk of selecting CHX-R and Mu-R. In addition, other potential resistance genes should be studied.

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.

High-level mupirocin resistance in methicillin-resistant staphylococci isolated from dogs and cats

BACKGROUND

Mupirocin is one of the few antimicrobials active against methicillin-resistant Staphylococcus aureus (MRSA), and is frequently used for the eradication of MRSA nasal colonisation in humans. Initially, mupirocin resistance was recognised in human S. aureus, including MRSA isolates, then also among coagulase-negative staphylococci (CoNS). Nowadays, mupirocin resistance is occasionally observed in canine staphylococci, along with Staphylococcus pseudintermedius (MRSP) strains, as well as CoNS, which usually show methicillin resistance. In the current study, high-level mupirocin resistance in methicillin-resistant staphylococci isolated from diseased dogs and cats was investigated.

RESULTS

Among 140 methicillin-resistant staphylococci isolates from dogs and cats, three showed high-level mupirocin resistance in a screening test using the agar disk diffusion method. One was recognised as methicillin-resistant S. aureus, one as methicillin-resistant S. pseudintermedius, and one as methicillin-resistant Staphylococcus haemolyticus. S. pseudintermedius and S. aureus were isolated from dogs, S. haemolyticus was obtained from a cat. All isolates showed high-level mupirocin resistance, confirmed by minimum inhibitory concentration (MIC) values of above 1024 μg/ml and the presence of the plasmid-located gene ileS2. This is the first report on the detection of high-level mupirocin resistance (HLMR) in S. haemolyticus of feline origin.

CONCLUSIONS

This study revealed the occurrence of HLMR in three Staphylococcus isolates obtained from companion animals in Poland. The results of this study indicate that the monitoring of mupirocin resistance in staphylococci of animal origin, especially in methicillin-resistant isolates, is strongly recommended.

Sequential evolution of virulence and resistance during clonal spread of community-acquired methicillin-resistant Staphylococcus aureus

The past two decades have witnessed an alarming expansion of staphylococcal disease caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). The factors underlying the epidemic expansion of CA-MRSA lineages such as USA300, the predominant CA-MRSA clone in the United States, are largely unknown. Previously described virulence and antimicrobial resistance genes that promote the dissemination of CA-MRSA are carried by mobile genetic elements, including phages and plasmids. Here, we used high-resolution genomics and experimental infections to characterize the evolution of a USA300 variant plaguing a patient population at increased risk of infection to understand the mechanisms underlying the emergence of genetic elements that facilitate clonal spread of the pathogen. Genetic analyses provided conclusive evidence that fitness (manifest as emergence of a dominant clone) changed coincidently with the stepwise emergence of (i) a unique prophage and mutation of the regulator of the pyrimidine nucleotide biosynthetic operon that promoted abscess formation and colonization, respectively, thereby priming the clone for success; and (ii) a unique plasmid that conferred resistance to two topical microbiocides, mupirocin and chlorhexidine, frequently used for decolonization and infection prevention. The resistance plasmid evolved through successive incorporation of DNA elements from non-S. aureus spp. into an indigenous cryptic plasmid, suggesting a mechanism for interspecies genetic exchange that promotes antimicrobial resistance. Collectively, the data suggest that clonal spread in a vulnerable population resulted from extensive clinical intervention and intense selection pressure toward a pathogen lifestyle that involved the evolution of consequential mutations and mobile genetic elements.

Mupirocin Resistance Among Methicillin Resistant Staphylococcus Isolates in a Tertiary Health Care Center

INTRODUCTION

The evolution of antibiotics in the last century has revolutionized the field of medicine and led this field to higher level of success in treating mild to severe infections, but the inappropriate use of these life saving drugs has been accompanied with the appearance of resistant strains to these agents.

AIMS & OBJECTIVES

The aim of the study was to determine the prevalence rate of high and low-level mupirocin resistance in methicillin resistant staphylococcus,and to find out resistance to other antibiotics.

MATERIALS & METHODS

This study was conducted on 100 Staphylococcus isolates recovered from pus samples. Conventional disc diffusion tests were used for the detection of high and low level mupirocin resistance (mupirocin 5µg and 200µg discs) and for various other antimicrobials for example cephalexin, erythromycin, doxycycline, oxacillin, linezolid etc. Results: Outof 100 Staphylococcus isolates processed during the study period in the department of microbiology, 74 were Staphylococcus aureus (S.aureus) and 26 were Coagulase negative Staphylococcus (CoNS). Among S.aureus 43.4% were Methicillin resistant Staphylococcus aureus (MRSA) and 56.6% were Methicillin sensitive Staphylococcus aureus (MSSA), whereas among CoNS 42% were methicillin resistant and 58% were methicillin sensitive. We observed 6.75% of high level mupirocin resistance among Staphylococcus aureus and 19.23% among Coagulase negative staphylococcus.

CONCLUSION

It was concluded that an inappropriate excessive use of mupirocin leads to a rapid increase in high-level resistance to mupirocin and other antibiotics in CoNS, affecting the treatment lines and success rate of infection control in hospital settings.

Mupirocin-resistant Staphylococcus aureus in Africa: a systematic review and meta-analysis

Background

Mupirocin is widely used for nasal decolonization of Staphylococcus aureus to prevent subsequent staphylococcal infection in patients and healthcare personnel. However, the prolonged and unrestricted use has led to the emergence of mupirocin-resistant (mupR) S. aureus. The aim of this systematic review was to investigate the prevalence, phenotypic and molecular characteristics, and geographic spread of mupR S. aureus in Africa.

Methods

We examined five electronic databases (EBSCOhost, Google Scholar, ISI Web of Science, MEDLINE, and Scopus) for relevant English articles on screening for mupR S. aureus from various samples in Africa. In addition, we performed random effects meta-analysis of proportions to determine the pooled prevalence of mupR S. aureus in Africa. The search was conducted until 3 August 2016.

Results

We identified 43 eligible studies of which 11 (26%) were obtained only through Google Scholar. Most of the eligible studies (28/43; 65%) were conducted in Nigeria (10/43; 23%), Egypt (7/43; 16%), South Africa (6/43; 14%) and Tunisia (5/43; 12%). Overall, screening for mupR S. aureus was described in only 12 of 54 (22%) African countries. The disk diffusion method was the widely used technique (67%; 29/43) for the detection of mupR S. aureus in Africa. The mupA-positive S. aureus isolates were identified in five studies conducted in Egypt (n = 2), South Africa (n = 2), and Nigeria (n = 1). Low-level resistance (LmupR) and high-level resistance (HmupR) were both reported in six human studies from South Africa (n = 3), Egypt (n = 2) and Libya (n = 1). Data on mupR-MRSA was available in 11 studies from five countries, including Egypt, Ghana, Libya, Nigeria and South Africa. The pooled prevalence (based on 11 human studies) of mupR S. aureus in Africa was 14% (95% CI =6.8 to 23.2%). The proportion of mupA-positive S. aureus in Africa ranged between 0.5 and 8%. Furthermore, the frequency of S. aureus isolates that exhibited LmupR, HmupR and mupR-MRSA in Africa were 4 and 47%, 0.5 and 38%, 5 and 50%, respectively.

Conclusions

The prevalence of mupR S. aureus in Africa (14%) is worrisome and there is a need for data on administration and use of mupirocin. The disk diffusion method which is widely utilized in Africa could be an important method for the screening and identification of mupR S. aureus. Moreover, we advocate for surveillance studies with appropriate guidelines for screening mupR S. aureus in Africa.

Bioluminescent murine models of bacterial sepsis and scald wound infections for antimicrobial efficacy testing

There are very few articles in the literature describing continuous models of bacterial infections that mimic disease pathogenesis in humans and animals without using separate cohorts of animals at each stage of disease. In this work, we developed bioluminescent mouse models of partial-thickness scald wound infection and sepsis that mimic disease pathogenesis in humans and animals using a recombinant luciferase-expressing Staphylococcus aureus strain (Xen29). Two days post-scald wound infection, mice were treated twice daily with a 2% topical mupirocin ointment for 7 days. For sepsis experiments, mice were treated intraperitoneally with 6 mg/kg daptomycin 2 h and 6 h post-infection and time to moribund monitored for 72 h. Consistent bacterial burden data were obtained from individual mice by regular photon intensity quantification on a Xenogen IVIS Lumina XRMS Series III biophotonic imaging system, with concomitant significant reduction in photon intensities in drug-treated mice. Post-mortem histopathological examination of wounds and bacterial counts in blood correlated closely with disease severity and total flux obtained from Xen29. The bioluminescent murine models provide a refinement to existing techniques of multiple bacterial enumeration during disease pathogenesis and promote animal usage reduction. The models also provide an efficient and information-rich platform for preclinical efficacy evaluation of new drug classes for treating acute and chronic human and animal bacterial infections.

Candida albicans/Staphylococcus aureus Dual-Species Biofilm as a Target for the Combination of Essential Oils and Fluconazole or Mupirocin

The effectiveness of essential oils (EOs), fluconazole (FLU) and mupirocin (MUP) used alone or in combination against mono-species and mixed Candida albicans/Staphylococcus aureus biofilms was examined. An experimentally established dual-species biofilm model, verified by fluorescence microscopy and viable cell counting, was used. Selected commercial EOs were tested: geranium, citronella and clove oils, which have been chemically characterized and found to differ in the content of the main components (qualitative and quantitative). As expected, C. albicans and S. aureus biofilms were less susceptible to fluconazole and mupirocin action, respectively, compared to the planktonic counterparts. However, the drug effectiveness in combination with the EOs was significantly improved, giving enhancement of biofilm eradication than caused by the antibiotics alone. Moreover, dual-species biofilm formation was limited by sub-MIC of EOs, and preformed mixed biofilm was eliminated more efficiently by combined action of drugs and EOs.

The effect of fennel essential oil in combination with antibiotics on Staphylococcus aureus strains isolated from carriers

An increase in the number of staphylococcal infections and carriers among medical staff has forced us to seek more and more effective antibacterial agents. Bacteria from the Staphylococcus genus possessing different mechanisms of resistance are the cause of nosocomial infections. The objective of our investigations was susceptibility of S. aureus strains isolated from nasal vestibule of medical students to fennel essential oil. The GC-MS analysis of fennel essential oil revealed eleven constituents among which a majority of trans-anethole (80%) was found. The D-tests showed iMLS_B (80%), cMLS_B and MS_B (10%) resistant phenotypes of S. aureus. The S. aureus isolates were intermediate to mupirocin (45%). Fennel essential oil increased the inhibition zone around cefoxitin, mupirocin, co-trimoxazole and ciprofloxacin with statistical significance. Our research showed that the fennel essential oil in combination with mupirocin may be considered as a natural alternative in eradication of S. aureus with iMLS_B, cMLS_B, MS_B resistant phenotypes and is able to decrease the growth rate of antibiotic resistance.

Anti-biofilm properties of a mupirocin spray formulation against Escherichia coli wound infections

Mupirocin ointment is a widely used topical drug for the treatment of bacterial skin infections. However, ointments have some limitations which motivated the development of a film forming spray of mupirocin. Mupirocin spray (2%) was formulated with Eudragit E100 as a film forming agent and tested for its antibacterial and anti-biofilm activities against Escherichia coli, a skin pathogen causing wound and surgical site infections. Treatment with mupirocin spray resulted in significant antibacterial and anti-biofilm activities (inhibition and disruption) with single spray and sub-actual dose concentrations at par with the commercial ointment concentration. The spray formulation was found to be non-toxic to fibroblast cells and greatly resisted removal from the site of application upon washing, in contrast to the ointment which was significantly removed after a single wash. This is the first study to develop and evaluate a spray formulation for mupirocin that forms a stable thin film for sustained release of the drug.

A Simple Way to Eradicate Methicillin-Resistant Staphylococcus aureus in Cynomolgus Macaques (Macaca fascicularis)

Our investigation of indoor-housed cynomolgus macaques (Macaca fascicularis) by using automated identification followed by antibiotic susceptibility testing revealed 1 of 7 immunocompetent animals and 2 of 9 immunosuppressed monkeys as carriers of methicillin-resistant Staphylococcus aureus (MRSA). Follow-up management involving mupirocin treatment resulted in the conversion of the 3 MRSA carriers into MRSA-negative cases. Prospective assessment of newly imported monkeys involving 24-h culture of nasal swabs on chromogenic agar revealed that 22% (18 of 82 animals) were MRSA-positive. Mupirocin treatment successfully converted all of the MRSA-positive macaques into non-carriers, suggesting the feasibility of this simple, one-step screening procedure for rapidly identifying MRSA carriers in large cohorts. In addition, 8 animals that had been diagnosed MRSA-positive and subsequently treated with mupirocin demonstrated no recolonization during follow-up, even under immunosuppressive conditions. We propose rapid screening using chromogenic agar followed by mupirocin treatment as a time- and cost-effective regimen for managing MRSA in cynomolgus monkeys.

A Cationic Amphiphilic Random Copolymer with pH-Responsive Activity against Methicillin-Resistant Staphylococcus aureus

In this report, we demonstrate the pH-dependent, in vitro antimicrobial activity of a cationic, amphiphilic random copolymer against clinical isolates of drug-resistant Staphylococcus aureus. The polymer was developed toward a long-term goal of potential utility in the treatment of skin infections. The proposed mechanism of action of the polymer is through selectively binding to bacterial membranes and subsequent disruption of the membrane structure/integrity, ultimately resulting in bacterial cell death. The polymer showed bactericidal activity against clinical isolates of methicillin-resistant or vancomycin-intermediate S. aureus. The polymer was effective in killing S. aureus at neutral pH, but inactive under acidic conditions (pH 5.5). The polymer did not exhibit any significant hemolytic activity against human red blood cells or display cytotoxicity to human dermal fibroblasts over a range of pH values (5.5–7.4). These results indicate that the polymer activity was selective against bacteria over human cells. Using this polymer, we propose a new potential strategy for treatment of skin infections using the pH-sensitive antimicrobial polymer agent that would selectively target infections at pH-neutral wound sites, but not the acidic, healthy skin.

[Letter to the Editor Concerning the Evaluation of Mupirocin Resistance in Methicillin-Resistant Staphylococcus aureus Strains]

Keywords: Drug Resistance, Bacterial; Methicillin-Resistant Staphylococcus aureus; Mupirocin; Staphylococcal Infections.

Methicillin-resistant Staphylococcus aureus in Stockholm, Sweden: Molecular epidemiology and antimicrobial susceptibilities to ceftaroline, linezolid, mupirocin and vancomycin in 2014

Methicillin-resistant Staphylococcus aureus (MRSA) is a public health problem worldwide. The aim of the present study was to investigate the molecular epidemiology and antimicrobial susceptibilities of MRSA strains in Stockholm, Sweden in 2014. Pulsed-field gel electrophoresis (PFGE) was used to characterise the strains. Antimicrobial susceptibilities to ceftaroline, linezolid and mupirocin were determined by the disc diffusion method. Etest was used to determine vancomycin susceptibility and to confirm resistance to ceftaroline, mupirocin and linezolid in non-susceptible strains. High-level ceftaroline-resistant strains [minimum inhibitory concentration (MIC)≥4mg/L] were confirmed by the broth microdilution method. spa typing was carried out on strains that were non-susceptible to the antibiotics tested. In total, 743 consecutive non-duplicate MRSA strains recovered in Stockholm in 2014 were investigated. PFGE analysis of the isolates revealed a population with 271 different PFGE patterns and three non-typeable strains. No PFGE type accounted for >10% of all strains. The most common PFGE types were MRSA-00-02 (6.9%) and MRSA-05-02 (4.6%). MRSA-05-02 is a USA300-like strain. The antimicrobial susceptibilities of the strains were as follows: ceftaroline, 98.5%; linezolid, 100%; mupirocin, 99.3%; and vancomycin, 100%. Two strains with spa t001 displayed ceftaroline MICs of 4mg/L. Three strains with spa types t002, t064 and t437 showed high-level mupirocin resistance (MIC>1024mg/L). In conclusion, there was a diverse genetic population among the MRSA isolates and no predominant genotype was found. This study identified a few strains with high-level ceftaroline resistance, high-level mupirocin resistance and high-risk genotypes.

Antibacterial Evaluation of Synthetic Thiazole Compounds In Vitro and In Vivo in a Methicillin-Resistant Staphylococcus aureus (MRSA) Skin Infection Mouse Model

The emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA), including strains resistant to current antibiotics, has contributed to an increase in the number of skin infections reported in humans in recent years. New therapeutic options are needed to counter this public health challenge. The aim of the present study was to examine the potential of thiazole compounds synthesized by our research group to be used topically to treat MRSA skin and wound infections. The broth microdilution method confirmed that the lead thiazole compound and four analogues are capable of inhibiting MRSA growth at concentrations as low as 1.3 μg/mL. Additionally, three compounds exhibited a synergistic relationship when combined with the topical antibiotic mupirocin against MRSA in vitro via the checkerboard assay. Thus the thiazole compounds have potential to be used alone or in combination with mupirocin against MRSA. When tested against human keratinocytes, four derivatives of the lead compound demonstrated an improved toxicity profile (were found to be non-toxic up to a concentration of 20 μg/mL). Utilizing a murine skin infection model, we confirmed that the lead compound and three analogues exhibited potent antimicrobial activity in vivo, with similar capability as the antibiotic mupirocin, as they reduced the burden of MRSA present in skin wounds by more than 90%. Taken altogether, the present study provides important evidence that these thiazole compounds warrant further investigation for development as novel topical antimicrobials to treat MRSA skin infections.

Enzymatic basis of "hybridity" in thiomarinol biosynthesis

Thiomarinol is a naturally occurring double-headed antibiotic that is highly potent against methicillin-resistant Staphylococcus aureus. Its structure comprises two antimicrobial subcomponents, pseudomonic acid analogue and holothin, linked by an amide bond. TmlU was thought to be the sole enzyme responsible for this amide-bond formation. In contrast to this idea, we show that TmlU acts as a CoA ligase that activates pseudomonic acid as a thioester that is processed by the acetyltransferase HolE to catalyze the amidation. TmlU prefers complex acyl acids as substrates, whereas HolE is relatively promiscuous, accepting a range of acyl-CoA and amine substrates. Our results provide detailed biochemical information on thiomarinol biosynthesis, and evolutionary insight regarding how the pseudomonic acid and holothin pathways converge to generate this potent hybrid antibiotic. This work also demonstrates the potential of TmlU/HolE enzymes as engineering tools to generate new "hybrid" molecules.