The community prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in older people living in their own homes: implications for treatment, screening and surveillance in the UK

Skin and soft tissue infections in the elderly

PURPOSE OF REVIEW

To highlight the peculiarity of skin and soft tissue infections (SSTIs) in elderly patients and to provide useful elements for their optimal management.

RECENT FINDINGS

In the COVID-19 era, early discharge from the hospital and implementation of outpatient management is of key importance.

SUMMARY

Elderly patients are at high risk of SSTIs due to several factors, including presence of multiple comorbidities and skin factors predisposing to infections. Clinical presentation may be atypical and some signs of severity, such as fever and increase in C-reactive protein, may be absent or aspecific in this patients population. An appropriate diagnosis of SSTIs in the elderly is crucial to avoid antibiotic overtreatment. Further studies should explore factors associated with bacterial superinfections in patients with pressure ulcers or lower limb erythema. Since several risk factors for methicillin-resistant Staphylococcus aureus (MRSA) may coexist in elderly patients, these subjects should be carefully screened for MRSA risk factors and those with high risk of resistant etiology should receive early antibiotic therapy active against MRSA. Physicians should aim to several objectives, including clinical cure, patient safety, early discharge and return to community. SSTIs in the elderly may be managed using long-acting antibiotics, but clinical follow-up is needed.

Occurence and Antimicrobial Resistant Patterns of Methicillin Resistant Staphylococcus Aureus (MRSA) Among Practicing Veterinarians in Kebbi State, Nigeria

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging zoonotic pathogen incriminated in causing multiple disease conditions in humans and livestock. Studies have shown relationships between livestock rearing and increased MRSA colonization risk among farm workers, and also suggest that livestock may serves as reservoirs of the bacteria and could also infect humans via close contact and consumption of contaminated animal products. The aim of this study was to investigate if practicing veterinarians with significant livestock contacts are at risk for MRSA colonization. Therefore, a non-randomized survey was conducted to establish the presence of MRSA among veterinarians practicing in Kebbi State Nigeria, using both cultural characteristics and molecular detection of the resistant gene (mecA). Forty-one (41) nasal swabs were aseptically collected. The detection rate of MRSA in the veterinarians was 14.6 %. The study revealed a high occurrence rate of MRSA among veterinarians in the study area. The relatively high prevalence recorded among veterinarians in this study could be attributed to the poor understanding of MRSA as a disease, its mode of transmission and its status in the country which have contributed immensely to the little/no awareness of MRSA among veterinarians and hence making it favourable for the bacteria (MRSA) to spread.

Clonal expansion of community-associated meticillin-resistant Staphylococcus aureus (MRSA) in people who inject drugs (PWID): prevalence, risk factors and molecular epidemiology, Bristol, United Kingdom, 2012 to 2017

Background: In 2015, Bristol (South West England) experienced a large increase in cases of meticillin-resistant Staphylococcus aureus (MRSA) infection in people who inject drugs (PWID).

Aim: We aimed to characterise and estimate the prevalence of MRSA colonisation among PWID in Bristol and test evidence of a clonal outbreak.

Methods: PWID recruited through an unlinked-anonymous community survey during 2016 completed behavioural questionnaires and were screened for MRSA. Univariable logistic regression examined associations with MRSA colonisation. Whole-genome sequencing used lineage-matched MRSA isolates, comparing PWID (screening and retrospective bacteraemia samples from 2012-2017) with non-PWID (Bristol screening) in Bristol and national reference laboratory database samples.

Results: The MRSA colonisation prevalence was 8.7% (13/149) and was associated with frequently injecting in public places (odds ratio (OR): 5.5; 95% confidence interval (CI):1.34–22.70), recent healthcare contact (OR: 4.3; 95% CI: 1.34–13.80) and injecting in groups of three or more (OR: 15.8; 95% CI: 2.51–99.28). People reporting any one of: injecting in public places, injection site skin and soft tissue infection or hospital contact accounted for 12/13 MRSA positive cases (sensitivity 92.3%; specificity 51.5%). Phylogenetic analysis identified a dominant clade associated with infection and colonisation among PWID in Bristol belonging to ST5-SCCmecIVg.

Conclusions: MRSA colonisation in Bristol PWID is substantially elevated compared with general population estimates and there is evidence of clonal expansion, community-based transmission and increased infection risk related to the colonising strain. Targeted interventions, including community screening and suppression therapy, education and basic infection control are needed to reduce MRSA infections in PWID.

Retrospective analysis of relationships among the dose regimen, trough concentration, efficacy, and safety of teicoplanin in Chinese patients with moderate-severe Gram-positive infections

Objectives

Teicoplanin, an antibiotic, has poor clinical efficacy when using the current drug label’s recommended regimen, which is approved by the China Food and Drug Administration. This study explores the appropriate loading and maintenance doses of teicoplanin and evaluates the therapeutic target of teicoplanin trough concentration (minimum concentration [C_min]).

Subjects and methods

All patients treated with teicoplanin from February 2015 to August 2016 at Zhengzhou Central Hospital were screened for enrollment. A total of 113 subjects were included and then divided into four groups: A (received three to six doses at a loading dose of 400 mg at 12-hour intervals, followed by maintenance dosing of 400 mg/day), B (received three doses at a loading dose of 400 mg at 12-hour intervals, followed by maintenance dosing of 400 mg/day), C (received two doses at a loading dose of 400 mg at 12-hour intervals, followed by maintenance dosing of 200 mg/day), and D (received one to three doses at a loading dose of 400 mg at 12-hour intervals, followed by maintenance dosing of 200 mg/day). C_min values of teicoplanin were detected with high-performance liquid chromatography on day 4, 30 minutes before maintenance-dose administration. Teicoplanin C_min, efficacy, and safety were compared among the four groups.

Results

Mean C_min differed significantly among the four groups (A, 18.11±6.37 mg/L; B, 15.91±4.94 mg/L; C, 17.06±5.66 mg/L; D, 11.97±3.76 mg/L) (P<0.001), with creatinine clearance of 89.62 (53.72–162.48), 49.66 (40.69–59.64), 27.17 (9.7–39.45), and 96.6 (17.63–394.73) mL/min, respectively. The ratio of loading dose for 3 days to creatinine clearance and serum C_min were significantly correlated (R=0.59, P<0.001). The correlation between the estimated probability of success and teicoplanin C_min was assessed using binary logistic regression (OR 2.049, P<0.001). Hepatotoxicity- and nephrotoxicity-incidence rates did not significantly differ among the four groups (P=0.859 and P=0.949, respectively).

Conclusion

A loading dose of 400 mg at 12-hour intervals three to six times is needed to achieve the early target range (15–20 mg/L) and improve the clinical efficacy rate for normal-renal-function patients. It is urgently necessary to amend the drug label for the recommended regimen.

Methicillin-resistant Staphylococcus aureus Nasal Carriage Among Patients Admitted at Shaqra General Hospital in Saudi Arabia

BACKGROUND AND OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) have been causing increasing problems in hospitals and nursing homes worldwide. Limited number of studies in Saudi Arabia has attempted to investigate infection and risk factors associated with nosocomial acquired MRSA. The present study was undertaken to determine the occurrence, prevalence, antibiotic susceptibility pattern and genetic characteristics of MRSA among admitted cases at Shaqra General Hospital (Saudi Arabia).

METHODOLOGY

This study was conducted from October, 2014 to March, 2015. Nasal swabs were taken from 220 patients (105 males and 115 females) admitted at Shaqra General Hospital. The isolates were identified as S. aureus based on morphology, Gram stain, catalase test, coagulase test and mannitol salt agar fermentation. Antibiotic susceptibility testing of MRSA was performed with standard disk diffusion method. All methicillin-resistant isolates were examined for the existence of the mecA gene by PCR technique.

RESULTS

Of the 220 patients, 90 (40.91%) were found to be nasal carriers of S. aureus. Among these 90 S. aureus isolates, 48 (21.82%) were MRSA. A statistically significant difference was only found for antibiotics usage between those with and without MRSA colonization. Antibiotic susceptibility pattern of isolated MRSA showed high susceptibility to vancomycin, linezolid, rifampicin, teicoplanin, complete resistance to penicillin, ampicillin, oxacillin and cefoxitin and intermediate resistance to amikacin, ciprofloxacin, teicoplanin, tetracycline and vancomycin.

CONCLUSION

A high prevalence of multidrug-resistant MRSA nasal carriage was found. The identification of MRSA carriers is a step towards establishing a control policy for MRSA and helps to identify measures needed to reduce colonization pressure.

Oral and Topical Antibiotics for Clinically Infected Eczema in Children: A Pragmatic Randomized Controlled Trial in Ambulatory Care

PURPOSE

Eczema may flare because of bacterial infection, but evidence supporting antibiotic treatment is of low quality. We aimed to determine the effect of oral and topical antibiotics in addition to topical emollient and corticosteroids in children with clinically infected eczema.

METHODS

We employed a 3-arm, blinded, randomized controlled trial in UK ambulatory care. Children with clinical, non-severely infected eczema were randomized to receive oral and topical placebos (control), oral antibiotic (flucloxacillin) and topical placebo, or topical antibiotic (fusidic acid) and oral placebo, for 1 week. We compared Patient Oriented Eczema Measure (POEM) scores at 2 weeks using analysis of covariance (ANCOVA).

RESULTS

We randomized 113 children (40 to control, 36 to oral antibiotic, and 37 to topical antibiotic). Mean (SD) baseline Patient Oriented Eczema Measure scores were 13.4 (5.1) for the control group, 14.6 (5.3) for the oral antibiotic group, and 16.9 (5.5) for the topical antibiotic group. At baseline, 104 children (93%) had 1 or more of the following findings: weeping, crusting, pustules, or painful skin. Mean (SD) POEM scores at 2 weeks were 6.2 (6.0) for control, 8.3 (7.3) for the oral antibiotic group, and 9.3 (6.2) for the topical antibiotic group. Controlling for baseline POEM score, neither oral nor topical antibiotics produced a significant difference in mean (95% CI) POEM scores (1.5 [-1.4 to 4.4] and 1.5 [-1.6 to 4.5] respectively). There were no significant differences in adverse effects and no serious adverse events.

CONCLUSIONS

We found rapid resolution in response to topical steroid and emollient treatment and ruled out a clinically meaningful benefit from the addition of either oral or topical antibiotics. Children seen in ambulatory care with mild clinically infected eczema do not need treatment with antibiotics.

Prevalence of MRSA colonization in an adult urban Indian population undergoing orthopaedic surgery

INTRODUCTION

Orthopaedic surgery is technically demanding, implant dependant and expensive. Infection translates into a prolonged morbidity and long-term use of antibiotics. The most common organism involved in osteo-articular infections is Staphylococcus aureus, and colonizes the anterior nares of 25-30% of the population. Carriers are at higher risk for staphylococcal infections after invasive medical or surgical procedures. Prevalence of methicillin resistant Staphylococcus aureus (MRSA) has not been assessed in patients admitted for orthopaedic surgery in the Indian setting.

AIM

To assess the preoperative prevalence of MRSA colonization in adult patients undergoing orthopaedic surgery in urban India.

MATERIALS AND METHODS

This is a retrospective analysis of patients from 2009 to 2013. A total of 1550 patients admitted for orthopaedic surgery were preoperatively screened with nasal and axillary swabs for MRSA. Swab-positive patients were treated with intranasal mupirocin ointment for 3 days followed by a repeat swab. A record was made of hospitalization in the year prior to surgery and the occurrence of surgical site infection (SSI).

RESULTS

A total of 690 males and 860 females had been screened for MRSA using an inexpensive kit costing 500 Indian rupees. For MRSA, 7/1550 (0.45%) nasal swabs were positive. No patient since 2009 has had a SSI with MRSA.

CONCLUSION

MRSA screening prior to orthopaedic surgery is a valuable and cost effective preoperative investigation even though the incidence is low. Mupirocin is effective in clearing MRSA from the nares and maybe used for 3 days to obtain elimination of the bacteria.

The prevalence and influencing factors of methicillin-resistant Staphylococcus aureus carriage in people in contact with livestock: A systematic review

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is becoming a serious epidemic worldwide. Recently, studies have shown that people in contact with livestock may have a greater chance of MRSA carriage. We aimed to establish the prevalence of MRSA among people in contact with livestock and review the factors influencing MRSA carriage.

METHODS

We systematically examined published epidemiologic studies on MRSA prevalence in people in contact with livestock using Pubmed, Medline, Embase, Ovid, and the Cochrane Library. Prevalence estimates were pooled using a random-effects model. Study heterogeneity was assessed using Q statistics and quantified with I(2) statistics.

RESULTS

Thirty-three eligible studies were included in this systematic review. Prevalence of MRSA ranged from 0.0%-85.8%. The pooled prevalence estimate of MRSA was 14.2% (95% confidence interval, 9.1%-20.1%) for people in contact with livestock. Substantial heterogeneity in eligible studies was noted (χ(2) = 1,025; P < .001; I(2) = 96.9%). Subgroup analysis showed the prevalence of MRSA was high in people from Europe (15.9%), farmers (18.2%), and by longitudinal study design (38.9%). Animal contact and intensity of animal contact were associated with increased risk of MRSA carriage.

CONCLUSION

Our findings suggest that there may be transmission of MRSA between animals and humans.

Antimicrobial resistance and characterisation of staphylococci isolated from healthy Labrador retrievers in the United Kingdom

BACKGROUND

Coagulase-positive (CoPS) and coagulase-negative (CoNS) staphylococci are normal commensals of the skin and mucosa, but are also opportunist pathogens. Meticillin-resistant (MR) and multidrug-resistant (MDR) isolates are increasing in human and veterinary healthcare. Healthy humans and other animals harbour a variety of staphylococci, including MR-CoPS and MR-CoNS. The main aims of the study were to characterise the population and antimicrobial resistance profiles of staphylococci from healthy non-vet visiting and non-antimicrobial treated Labrador retrievers in the UK.

RESULTS

Nasal and perineal samples were collected from 73 Labrador retrievers; staphylococci isolated and identified using phenotypic and biochemical methods. They were also confirmed by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS), PCR of the nuc gene and PCR and sequencing of the tuf gene. Disc diffusion and minimum inhibitory concentration (MIC) susceptibility tests were determined for a range of antimicrobials. In total, 102 CoPS (S. pseudintermedius n = 91, S. aureus n = 11) and 334 CoNS isolates were detected from 99% of dogs in this study. In 52% of dogs CoNS only were detected, with both CoNS and CoPS detected in 43% dogs and CoPS only detected in 4% of dogs. Antimicrobial resistance was not common among CoPS, but at least one MDR-CoNS isolate was detected in 34% of dogs. MR-CoNS were detected from 42% of dogs but no MR-CoPS were isolated. S. epidermidis (52% of dogs) was the most common CoNS found followed by S. warneri (30%) and S. equorum (27%), with another 15 CoNS species isolated from ≤ 15% of dogs. S. pseudintermedius and S. aureus were detected in 44% and 8% of dogs respectively.

CONCLUSIONS

MR- and MDR-CoPS were rare. However a high prevalence of MR- and MDR-CoNS were found in these dogs, even though they had no prior antimicrobial treatment or admission to veterinary premises. These findings are of concern due to the potential for opportunistic infections, zoonotic transmission and transmission of antimicrobial resistant determinants from these bacteria to coagulase positive staphylococci.

Incidence and characterisation of methicillin-resistant Staphylococcus aureus (MRSA) from nasal colonisation in participants attending a cattle veterinary conference in the UK

We sought to determine the prevalence of nasal colonisation with methicillin-resistant Staphylococcus aureus among cattle veterinarians in the UK. There was particular interest in examining the frequency of colonisation with MRSA harbouring mecC, as strains with this mecA homologue were originally identified in bovine milk and may represent a zoonotic risk to those in contact with dairy livestock. Three hundred and seven delegates at the British Cattle Veterinarian Association (BCVA) Congress 2011 in Southport, UK were screening for nasal colonisation with MRSA. Isolates were characterised by whole genome sequencing and antimicrobial susceptibility testing. Eight out of three hundred and seven delegates (2.6%) were positive for nasal colonisation with MRSA. All strains were positive for mecA and none possessed mecC. The time since a delegate's last visit to a farm was significantly shorter in the MRSA-positive group than in MRSA-negative counterparts. BCVA delegates have an increased risk of MRSA colonisation compared to the general population but their frequency of colonisation is lower than that reported from other types of veterinarian conference, and from that seen in human healthcare workers. The results indicate that recent visitation to a farm is a risk factor for MRSA colonisation and that mecC-MRSA are rare among BCVA delegates (<1% based on sample size). Contact with livestock, including dairy cattle, may still be a risk factor for human colonisation with mecC-MRSA but occurs at a rate below the lower limit of detection available in this study.

Nasal self-swabbing for estimating the prevalence of Staphylococcus aureus in the community

Staphylococcus aureus remains a significant cause of morbidity and mortality and, therefore, a burden on healthcare systems. Our aim was to estimate the current rate of nasal S. aureus carriage in the general population and to determine the feasibility of nasal self-swabbing as a means of detection. Two thousand people (1200 adults and 800 children) from a single NHS general practice in Southampton, UK, were randomly selected from a general practice age sex register, stratified by age and sex, and invited to undertake nasal self-swabbing in their own home. Overall, 362 (32.5%) swabs from adults and 168 (22%) from children were returned. Responses were greater for adults and those of increased age, female gender and decreasing socio-economic deprivation. The overall estimated practice carriage rate of S. aureus directly standardized for age sex was 28% [95% confidence interval (CI) 26.1-30.2%]. Carriage of meticillin-susceptible S. aureus was 27% (95% CI 26.1-30.2%), whilst that of meticillin-resistant S. aureus was 1.9% (95% CI 0.7-3.1%). Although nasal self-swabbing rates were relatively low, they are comparable to other studies and may allow large population-based carriage studies to be undertaken at relatively low cost. Importantly, this study updates prevalence data for S. aureus carriage in the community.

Treatment of skin and soft tissue infections in the elderly: A review

BACKGROUND

Skin and soft tissue infections (SSTIs) have become the second most common type of infection among persons residing in long-term care facilities.

OBJECTIVE

The purpose of this article was to review the latest information on SSTIs among the elderly, including age-related changes, challenges, and treatment strategies in the era of emerging bacterial resistance.

METHODS

Relevant information was identified through a search of MEDLINE (1970-April 2010), International Pharmaceutical Abstracts (1970-April 2010), and Google Scholar using the terms skin and soft tissue infection, skin and skin structure infection, cellulitis, treatment guidelines, and elderly. Additional publications were found by searching the reference lists of the identified articles. Trials published since 1970 were selected for this review if they prospectively evaluated mostly adults (≥18 years of age), included >50 patients, and reported diagnostic criteria as well as clinical outcomes in patients treated for simple or complicated SSTIs.

RESULTS

Fifty-eight of 664 identified studies were selected and included in this review. A search of the literature did not identify any prospective clinical trials that were conducted exclusively in the elderly. Information on the treatment of SSTIs in the elderly was based solely on clinical studies that were conducted in adults in general. As recommended by the Infectious Diseases Society of America (IDSA) 2008 update, SSTIs should be suspected in elderly patients who have skin lesions and present with a decline in functional status, with or without fever. Patients who present with symptoms of systemic toxicity should be hospitalized for further evaluation. Current challenges in the management of SSTIs include the rapid emergence of community-acquired, methicillin-resistant Staphylococcus aureus (CA-MRSA), the emergence of macrolide-resistant streptococci within the past decade, and the lack of a reliable algorithm to differentiate potentially life-threatening SSTIs that require aggressive interventions and prompt hospitalization from those that can be managed in an outpatient setting. S aureus was the most common cause of SSTIs, being isolated in 42.8% (5015/11,723) of wounds, followed by streptococci. Common SSTIs in the elderly such as shingles, diabetic foot infections, infected pressure ulcers, and scabies, and their treatment were also discussed. Based on reviews of published trials, treatment of simple SSTIs generally consisted of administration of agents with activity against S aureus and Streptococcus species such as a penicillinase-resistant β-lactam, a first-generation cephalosporin, or clindamycin. Broadening of the antimicrobial spectrum to include gram-negative and anaerobic organisms should be implemented for complicated SSTIs such as diabetic foot infections and infected pressure ulcers. Local rates of MRSA, CA-MRSA, and macrolide-resistant streptococci should be considered when selecting empiric therapy.

CONCLUSIONS

A search of the literature did not identify any prospective clinical trials on the treatment of SSTIs in the elderly; therefore, it is recommended to follow treatment based on the current IDSA guidelines. More research and publications are needed to establish proper selection of antimicrobial agents, treatment strategies, and duration of therapy of SSTIs in the elderly population.

Performance of the BD GeneOhm methicillin-resistant Staphylococcus aureus (MRSA) PCR assay for detecting MRSA nasal colonization in Taiwanese adults

BACKGROUND/PURPOSE

A rapid diagnostic method for methicillin-resistant Staphylococcus aureus (MRSA) has been implemented for surveillance of the at-risk population, but its performance in those without traditional risk factors is not clear. The objective of this study was to evaluate MRSA colonization status by comparing the performance of the BD GeneOhm MRSA polymerase chain reaction (PCR) assay with that of conventional culture during a 3-month active surveillance of Taiwanese adults in the community.

METHODS

From 1 October 2007 to 28 December 2007, adults (≥ 18 years old) attending a mandatory health examination arranged by their employers as a part of the workplace health promotion program at three medical centers in northern Taiwan were enrolled in the study. No healthcare workers were included. A total of 498 paired nasal swabs were prospectively obtained and used for both the BD GeneOhm MRSA PCR assay and conventional culture.

RESULTS

Of the 498 paired nasal swabs, 14 (2.8%) were positive for MRSA by conventional culture and 34 (6.8%) were positive by the BD GeneOhm MRSA PCR assay (p < 0.005). Thirteen specimens were both culture- and PCR-positive, and 463 samples were both culture- and PCR-negative. There were two discordant results: 21 specimens were culture-negative/PCR-positive, and one was culture-positive/PCR-negative. The simple kappa coefficient for measuring the agreement between conventional culture and the MRSA PCR assay was 0.52.

CONCLUSION

This study demonstrates the feasibility of using both the MRSA PCR assay and conventional culture as surveillance tools. Also, the MRSA-positive rate detected by MRSA PCR assay was significantly higher than that of conventional culture.

Prevalence of and risk factors for MRSA carriage in companion animals: a survey of dogs, cats and horses

We investigated the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage in a convenience sample of purposely selected populations of dogs, cats and horses in the Greater London area. Swabs from carriage sites were pooled, enriched and processed by standard bacteriological methods. The presence of nuc and mecA was confirmed for MRSA. Risk factors were investigated among veterinary treatment group animals using exact logistic regression analysis. Twenty-six (1.53%) MRSA carriers were identified in the 1692 animals (15/704 dogs, 8/540 cats, 3/152 horses). Animals presenting for veterinary treatment more frequently carried MRSA than healthy animals (OR 7.27, 95% CI 2.18-24.31, P<0.001). Concurrent carriage of non-MRSA coagulase-positive staphylococci was associated with MRSA carriage (OR 0.088, 95% CI 0.016-0.31, P<0.001); none of the other 13 putative risk factors was significant. MRSA carriage was rare in the selected companion animal populations. The absence of typical risk factors indicates that companion animals act as contaminated vectors rather than as true reservoirs.

Staphylococcal enterotoxins

Staphylococcus aureus (S. aureus) is a Gram positive bacterium that is carried by about one third of the general population and is responsible for common and serious diseases. These diseases include food poisoning and toxic shock syndrome, which are caused by exotoxins produced by S. aureus. Of the more than 20 Staphylococcal enterotoxins, SEA and SEB are the best characterized and are also regarded as superantigens because of their ability to bind to class II MHC molecules on antigen presenting cells and stimulate large populations of T cells that share variable regions on the β chain of the T cell receptor. The result of this massive T cell activation is a cytokine bolus leading to an acute toxic shock. These proteins are highly resistant to denaturation, which allows them to remain intact in contaminated food and trigger disease outbreaks. A recognized problem is the emergence of multi-drug resistant strains of S. aureus and these are a concern in the clinical setting as they are a common cause of antibiotic-associated diarrhea in hospitalized patients. In this review, we provide an overview of the current understanding of these proteins.

Have the organisms that cause breast abscess changed with time?--Implications for appropriate antibiotic usage in primary and secondary care

Many patients with breast abscess are managed in primary care. Knowledge of current trends in the bacteriology is valuable in informing antibiotic choices. This study reviews bacterial cultures of a large series of breast abscesses to determine whether there has been a change in the causative organisms during the era of increasing methicillin-resistant Staphylococcus aureus (MRSA). Analysis was undertaken of all breast abscesses treated in a single unit over 2003 - 2006, including abscess type, bacterial culture, antibiotic sensitivity and resistance patterns. One hundred and ninety cultures were obtained (32.8% lactational abscess, 67.2% nonlactational). 83% yielded organisms. Staphylococcus aureus was the commonest organism isolated (51.3%). Of these, 8.6% were MRSA. Other common organisms included mixed anaerobes (13.7%), and anaerobic cocci (6.3%). Lactational abscesses were significantly more likely to be caused by S. aureus (p < 0.05). Methicillin-resistant Staphylococcus aureus rates were not statistically different between lactational and nonlactational abscess groups. Appropriate antibiotic choices are of great importance in the community management of breast abscess. Ideally, microbial cultures should be obtained to institute targeted therapy but we recommend the continued use of flucloxacillin with or without metronidazole (or amoxicillin-clavulanate as a single preparation) as initial empirical therapy.

Best practice in primary care pathology: review 12

This twelfth best practice review examines four series of common primary care questions in laboratory medicine: (i) antiepileptic drug monitoring; (ii) infectious diarrhoea; (iii) methicillin resistant Staphylococcus aureus; and (iv) brain natriuretic peptide. The review is presented in question–answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Meticillin-resistant Staphylococcus aureus carriage in UK veterinary staff and owners of infected pets: new risk groups

Meticillin-resistant Staphylococcus aureus (MRSA) nasal carriage on admission to hospital remains one of the most important risk factors for subsequent infection. Identification of high risk groups for MRSA carriage is vital for the success of infection control programmes. Veterinary staff may be one such risk group but little is known about pet owners and the role of contact with infected pets. As part of a UK-wide case-control study investigating risk factors for MRSA infection in dogs and cats between 2005 and 2008, 608 veterinary staff and pet owners in contact with 106 MRSA and 91 meticillin-susceptible S. aureus (MSSA)-infected pets were screened for S. aureus nasal carriage. Laboratory isolation and characterisation included salt broth enrichment, standard and automated microbiological tests, demonstration of the S. aureus-specific thermonuclease gene (nuc) and of mecA, and polymerase chain reaction-based lineage characterisation. MRSA carriage was 12.3% in veterinarians attending MRSA-infected animals and 7.5% in their owners. In the MSSA control group, MRSA carriage was 4.8% in veterinary staff and 0% in owners. Veterinary staff carried MRSA more frequently than owners (odds ratio: 2.33; 95% confidence interval: 1.10-4.93). All MRSA from humans and all but one animal MRSA were CC22 or CC30, typical for hospital MRSA in the UK. This study indicates for the first time an occupational risk for MRSA carriage in small animal general practitioners. Veterinary staff and owners of MRSA-infected pets are high risk groups for MRSA carriage despite not having direct hospital links. Strategies to break the cycle of MRSA infection must take these potential new reservoirs into account.

Companion animals: a reservoir for methicillin-resistant Staphylococcus aureus in the community?

This article reviews the literature on the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in dogs, cats and horses. Over the past 10 years, MRSA has emerged as an important pathogen in veterinary medicine, especially in countries with a high MRSA burden in human hospitals. During the same period, community-associated MRSA (CA-MRSA) infections in humans without apparent links to healthcare facilities have increased dramatically. Although animal infections occur outside human hospitals, significant epidemiological, clinical and genetic differences exist between CA-MRSA in humans and the majority of MRSA infections in the different animal species. The recognition of MRSA in animals has raised concern over their role as potential reservoirs or vectors for human MRSA infection in the community. However, available data on MRSA transmission between humans and companion animals are limited and the public health impact of such transmission needs to be the subject of more detailed epidemiological studies.

Community-associated methicillin-resistant Staphylococcus aureus infections

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has been recognized for over a decade, and usually refers to MRSA identified in previously healthy individuals with no recognized MRSA risk factors. Infections range from minor skin and soft tissue infections, through to severe pneumonia and necrotizing fasciitis. This review summarizes the current data on the epidemiology and molecular features of CA-MRSA, in addition to diagnosis and therapeutic measures. We also refer to current national guidelines for the management of these infections. Areas of agreement include the important genotypic and phenotypic differences of community MRSA strains compared with hospital strains. Areas of controversy include the precise epidemiological definition of community-acquired/associated MRSA. Fortunately, true CA-MRSA can be differentiated from hospital MRSA by molecular techniques, as discussed herein. Recent interest has focused on the changing epidemiology of CA-MRSA. Worldwide, CA-MRSA is now seen outside of the initial specific population groups, and in the USA, the successful USA300 community strain is beginning to spread back into hospitals. Reasons why USA300 remains relatively uncommon in Europe are unclear. Topics timely for research include the investigation of the epidemiology of infections and evolutionary genomics.

'Feral' and 'wild'-type methicillin-resistant Staphylococcus aureus in the United Kingdom

Circulation of methicillin-resistant Staphylococcus aureus (MRSA) outside hospitals could alter the impact of hospital-based control strategies. We investigated two groups of cases (each matched to controls with MRSA): 61 'community cases' not in acute hospital in the year before MRSA isolation; and 21 cases with ciprofloxacin-sensitive (CipS) MRSA. Multi-locus sequence typing, spa-typing and Panton-Valentine leukocidin gene testing were performed and demographics obtained. Additional questionnaires were completed by community case GPs. Community cases comprised 6% of Oxfordshire MRSA. Three community cases had received no regular healthcare or antibiotics: one was infected with CipS. Ninety-one percent of community cases had healthcare-associated sequence type (ST)22/36; CipS MRSA cases had heterogeneous STs but many had recent healthcare exposure. A substantial minority of UK MRSA transmission may occur outside hospitals. Hospital strains are becoming 'feral' or persisting in long-term carriers in the community with regular healthcare contacts; those with recent healthcare exposure may nevertheless acquire non-hospital epidemic MRSA strains in the community.

Clinical, molecular and epidemiological description of a cluster of community-associated methicillin-resistant Staphylococcus aureus isolates from injecting drug users with bacteraemia

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an increasing problem, predominantly in previously healthy individuals including notable risk groups such as the homeless, those who play close-contact sports, military personnel, men who have sex with men (MSM) and injecting drug users (IDUs). Over a 5-month period, four IDUs were admitted to Addenbrooke's Hospital, Cambridge, UK, with MRSA bacteraemia. All four patients presented with complex clinical features, with more than one focus of infection, and were linked epidemiologically. The atypical antibiogram of the MRSA isolates (ciprofloxacin-susceptible) prompted further characterization, both phenotypically (antibiotic resistance typing; phage typing) and genotypically (detection of toxin genes by PCR; pulsed-field gel electrophoresis (PFGE); Staphylococcal chromosome cassette (SCC) mec typing; multi-locus sequence typing (MLST)). All four isolates had similar antibiograms, were Panton-Valentine Leucocidin (PVL) toxin gene-negative, harboured SCCmec type IV and were closely related as shown by phage typing and PFGE. These isolates were representatives of a community-associated clone, ST1-MRSA-IV, known to be circulating in IDUs in the UK since 2001. This paper presents a detailed description of the clinical, microbiological and epidemiological features of a series of CA-MRSA bacteraemias in IDUs in the UK.

The prevalence of methicillin resistant Staphylococus aureus in orthopaedics in a non-selective screening policy

BACKGROUND

The aim of this study was to assess the true incidence and prevalence of MRSA colonisation and infection in the elective and trauma orthopaedic population in Rotherham District General Hospital.

MATERIALS AND METHODS

This prospective study non-selectively screened 690 consecutive trauma and elective orthopaedic patients over three months in 2005.

RESULTS

Of these, 27 were positive for either colonisation or wound infection with MRSA. Of those, 13 were previously known to have been colonised with MRSA and the 14 others were unexpectedly either colonised or subsequently developed wound infections. The new cases would not have been identified using any current selective screening protocol, as they did not fall into a high-risk category. Many were young, had no co-morbidities and no contact with hospitals in the past. Our study seems to indicate that selective screening will miss a significant number of cases.

CONCLUSION

We conclude that MRSA screening for all orthopaedic patients is needed when admitted to hospital, as colonisation is no longer confined to what has been previously identified as high-risk groups. The consequences of a subsequent MRSA infection have significant implications, socially, financially and clinically.

Antimicrobial drugs and community-acquired methicillin-resistant Staphylococcus aureus, United Kingdom

We report results of a case-control study of the association between receipt of antimicrobial agents and diagnosis of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) in the United Kingdom. Eligible adults, selected from the General Practice Research Database, had no previous diagnosis of MRSA, no hospitalization in the past 2 years, and > or = 2 years of follow-up recorded in the database. For 2000-2004, we identified 1,981 MRSA case-patients and 19,779 matched control-patients. The odds ratios (ORs) and 95% confidence intervals (CIs) of MRSA diagnosis for patients who were prescribed 1, 2-3, or > or = 4 antimicrobial drugs were 1.57 (CI 1.36-1.80), 2.46 (CI 2.15-2.83), and 6.24 (CI 5.43-7.17), respectively. Risk for community-acquired MRSA increased with number of antimicrobial drug prescriptions, appeared to vary according to antimicrobial drug classes prescribed the previous year, and was highest for quinolones (OR 3.37, CI 2.80-4.09) and macrolides (OR 2.50, CI 2.14-2.91).

Frequent detection of multidrug-resistant pneumonia-causing bacteria in the pneumonia lung tissues of patients with hematological malignancies

Pneumonia is a critical issue during the agonal phase, and often becomes lethal in the absence of pathogen detection. Autopsy is a powerful tool for analyzing the cause of a patient's death, progression of the disease, and the therapeutic response. However, it is frequently limited to the identification of bacterial strains. To elucidate the pathogenesis during the agonal phase of pneumonia, intrapulmonary sputum was harvested by directly inserting a swab into a resected lung, and the bacterial composition was analyzed using both pathological and microbiological techniques from 15 patients with hematological malignancies, and the results were compared with those from 25 patients with other medical and surgical diseases. Among the 54 bacteria strains isolated from the 40 patients, multidrug-resistant strains were significantly more prevalent in hematological group than in other diseases (16/21 versus 11/33, P = .002). Enterococcus faecium was preferentially isolated from the hematological patients, whereas the methicillin-resistant Staphylococcus aureus was predominantly found in the nonhematological group. Two coagulase-negative Staphylococcus epidermidis strains in hematological diseases may be diagnosed as causative bacteria of pneumonia by both bacterial and pathological techniques. Although the results of this study may not be directly applicable for clinical diagnosis, this approach has a potential to become not only a diagnostic method for bacterial pneumonia, but may be also useful for the analysis of multidrug-resistant pathogens.

Financial implications of plans to combat methicillin-resistant Staphylococcus aureus (MRSA) in an orthopaedic department

INTRODUCTION

The aim of this study was to calculate retrospectively the cost of MRSA infections in the elective and trauma orthopaedic population in Rotherham District General Hospital in a 3-month period during 2005.

PATIENTS AND METHODS

A total of 686 patients were admitted to the orthopaedic wards and the surgical wounds 10 patients became infected with MRSA.

RESULTS

The cost of these infections when extrapolated over 12 months was pound384,000 excluding staff costs.

CONCLUSIONS

The key in the fight against MRSA in the hospital setting is multifactorial and requires a combination of measures. Our solution is: cohort nursing; non-selective screening of all admissions to the orthopaedic wards; use of a polymerase chain reaction as a diagnostic tool; ring-fencing of beds; and separate wound dressing rooms for each ward. The total cost is projected to be pound301,000.

Meticillin-resistant Staphylococcus aureus carriage among district nurse patients and medical admissions in a UK district

We studied the prevalence of meticillin-resistant Staphylococcus aureus (MRSA) carriage in two defined community populations and assessed risk factors associated with MRSA colonization. The study was designed as a population prevalence survey and was carried out in the medical assessment unit (MAU) of the local hospital and the district nurse patient (DNP) population in Huntingdonshire. In all, 162 participants were recruited, 91 were from MAU and 71 from the DNP population. MRSA was found in 21.1% [confidence interval (CI): 11.6-30.4] of the DNP study population and 6.6% (CI 1.5-11.7) of the MAU study population. Factors found to be significantly associated with MRSA colonization were age (76.6 years, P=0.008), presence of wound/ulcer (P=0.012), hospital admission in the past year (P=0.017), past history of MRSA (P<0.001), and antibiotic use in the preceding six months (P=0.016). The only independent predictor for MRSA colonization was found to be past history of MRSA (adjusted odds ratio: 8.53; CI: 2.11-34.43; P=0.003). The DNP population are a significant reservoir for MRSA in the community and policies on screening high-risk patients need to reflect this.

A new class of nifuroxazide analogues: Synthesis of 5-nitrothiophene derivatives with antimicrobial activity against multidrug-resistant Staphylococcus aureus

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been an increasing problem worldwide since the initial reports over 40 years ago. To examine new drug leads with potential antibacterial activities, 14 p-substituted benzoic acid [(5-nitro-thiophen-2-yl)-methylene]-hydrazides were designed, synthesized, and tested against standard and multidrug-resistant S. aureus strains by serial dilution tests. All compounds exhibited significant bacteriostatic activity and some of them also showed bactericidal activity. The results confirmed the potential of this class of compounds as an alternative for the development of selective antimicrobial agents.

Methicillin-resistant Staphylococcus aureus in an Irish orthopaedic centre: a five-year analysis

This prospective five-year study analyses the impact of methicillin-resistant Staphylococcus aureus (MRSA) on an Irish orthopaedic unit. We identified 318 cases of MRSA, representing 0.76% of all admissions (41,971). A total of 240 (76%) cases were colonised with MRSA, while 120 (37.7%) were infected. Patients were admitted from home (218; 68.6%), nursing homes (72; 22.6%) and other hospitals (28; 8.8%). A total of 115 cases (36.6%) were colonised or infected on admission. Many patients were both colonised and infected at some stage. The length of hospital stay was almost trebled because of the presence of MRSA infection. Encouragingly, overall infection rates have not risen significantly over the five years of the study despite increased prevalence of MRSA. However, the financial burden of MRSA is increasing, highlighting the need for progress in understanding how to control this resistant pathogen more effectively.

Methicillin-resistant Staphylococcus aureus on orthopaedic wards: incidence, spread, mortality, cost and control

We examined the rates of infection and colonisation by methicillin-resistant Staphylococcus aureus (MRSA) between January 2003 and May 2004 in order to assess the impact of the introduction of an MRSA policy in October 2003, which required all admissions to be screened. Emergency admissions were treated prophylactically and elective beds ring-fenced. A total of 5,594 admissions were cross-referenced with 22,810 microbiology results. The morbidity, mortality and cost of managing MRSA-carrying patients, with a proximal fracture of the femur were compared, in relation to age, gender, American Society of Anaesthesiologists grade and residential status, with a group of matched controls who were MRSA-negative. In 2004, we screened 1795 of 1,796 elective admissions and MRSA was found in 23 (1.3%). We also screened 1,122 of 1,447 trauma admissions and 43 (3.8%) were carrying MRSA. All ten ward transfers were screened and four (40%) were carriers (all p < 0.001). The incidence of MRSA in trauma patients increased by 2.6% per week of inpatient stay (r = 0.97, p < 0.001). MRSA developed in 2.9% of trauma and 0.2% of elective patients during that admission (p < 0.001). The implementation of the MRSA policy reduced the incidence of MRSA infection by 56% in trauma patients (1.57% in 2003 (17 of 1,084) to 0.69% in 2004 (10 of 1,447), p = 0.035). Infection with MRSA in elective patients was reduced by 70% (0.56% in 2003 (7 of 1,257) to 0.17% in 2004 (3 of 1,806), p = 0.06). The cost of preventing one MRSA infection was 3,200 pounds. Although colonisation by MRSA did not affect the mortality rate, infection by MRSA more than doubled it. Patients with proximal fractures of the femur infected with MRSA remained in hospital for 50 extra days, had 19 more days of vancomycin treatment and 26 more days of vacuum-assisted closure therapy than the matched controls. These additional costs equated to 13,972 pounds per patient. From this experience we have been able to describe the epidemiology of MRSA, assess the impact of infection-control measures on MRSA infection rates and determine the morbidity, mortality and economic cost of MRSA carriage on trauma and elective orthopaedic wards.

Community-Acquired Methicillin Resistant Staphylococcus aureus Skin Infection

Staphylococcus aureus is one of the most common pathogens in skin and soft tissue infections, as well as in potentially serious nosocomial infections in patients who acquire it when hospitalized. Penicillin was introduced in the 1940's as an effective treatment against S. aureus. However, shortly after penicillin's introduction, penicillin resistance to S. aureus emerged due to a plasmid-mediated beta-lactamase enzyme. In 1959, a semisynthetic penicillin, methicillin was introduced to overcome the resistance problem. However, within a year, bacteria resistant to methicillin and other penicillinase stable beta-lactams, were present. Worldwide emergence of methicillin-resistant S aureus (MRSA) was established by the 1980's. Since that time, MRSA has become widespread in hospitals and long-term care facilities around the world, accounting for numerous nosocomial infections. Recently, there has been an alarming increase in the incidence of community-acquired MRSA (CA-MRSA). Patients with CA-MRSA began to be reported in the early 1990's and its prevalence has continued to increase. This paper summarizes the current information known about CA-MRSA as it relates to skin infections including populations at risk, clinical presentation, and treatment options.

Control of a methicillin-resistant Staphylococcus aureus (MRSA) outbreak in a day-care institution

This article describes an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in two institutions for multi-handicapped children in Copenhagen. The aim of the study was to determine whether it was possible to eradicate MRSA in a setting with multi-handicapped children and staff where there was a high degree of physical interaction. This was a prospective interventional uncontrolled cohort study that took place from January 2003 to March 2005. All individuals in close contact with the two institutions and/or in close contact with an MRSA-colonized subject from the outbreak were included in the study: 38 children, 60 staff members and 12 close relatives of colonized subjects. Infection control measures included screening all individuals. When MRSA infection or colonization was found, an attempt was made to eradicate MRSA, staff education was undertaken and attempts were made to determine the route of transmission. Eleven individuals were found to be positive for MRSA (10.0%). All isolates were identical by pulsed-field gel electrophoresis and harboured the staphylococcal cassette chromosome mec (SCCmec) type IV. All colonized and infected individuals were associated with a single room in one of the institutions. MRSA was eradicated from all the colonized and infected subjects. This study shows that it is possible to control an MRSA outbreak in institutions for multi-handicapped children where there is a high degree of physical contact.

Community-onset healthcare-associated MRSA bacteraemia in a district general hospital

Methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia is associated with significant mortality and morbidity. This retrospective study involved 76 episodes over four years in a district general hospital in the UK. Twenty-eight of these episodes (36.8%) occurred within 72 h of admission. All of these, however, had risk factors for MRSA acquisition and were classified as healthcare-associated bacteraemias. The mortality rates (all causes) at seven days and three months were 31.5% and 53.4%, respectively. Ten patients died before targeted therapy could be commenced. All patients in the study had multiple comorbidities, and pneumonia was a common diagnosis. Previous antibiotics, increased age, admission on surgical wards/intensive care units, and the presence of central venous cannulae and urinary catheters were risk factors for infection. In 48.7% of episodes, patients were not known to be colonized with MRSA prior to their bacteraemia. Empirical targeted therapy should be given to patients with risk factors for MRSA and staphylococci in blood cultures pending susceptibility results. Increased use of screening may also be required to reduce transmission and increase the likelihood of appropriate empirical antimicrobial therapy. Eradication of MRSA from carriers in the community should be considered to reduce the number of community-onset healthcare-associated bacteraemias.

MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003

OBJECTIVE

To describe the incidence and determinants of methicillin resistant and methicillin sensitive Staphylococcus aureus (MRSA and MSSA) bacteraemia in patients presenting to acute hospitals.

DESIGN

Anonymised record linkage study with information from hospital information systems and microbiology databases.

SETTING

One teaching hospital and one district general hospital in Oxfordshire.

PARTICIPANTS

All patients admitted to a teaching hospital 1 April 1997 to 31 March 2003 and to a district general hospital 1 April 1999 to 31 March 2003.

MAIN OUTCOME MEASURES

Detection of MRSA and MSSA from blood cultures taken during the first two days of admission to hospital.

RESULTS

In the teaching hospital, there were 479 patients with MSSA and 116 with MRSA bacteraemia admitted from the community. Among this group, which comprised 24% of all hospital MRSA cases, 31% (36 cases) of patients had been admitted to renal, oncology, or haematology services for intensive day case therapy. The 69% remaining were most commonly patients admitted as medical or surgical emergencies. At least 91% had been in hospital previously; the median time since discharge was 46 days. About half of cases were in patients in whom MRSA had not been isolated before. Similar epidemiology was observed in the district general hospital.

CONCLUSION

Diagnostic algorithms and policies on use of antibiotics need to reflect the fact that a quarter of hospital MRSA cases occur in patients who have previously been in hospital and are subsequently readmitted.

Prevalence of methicillin-resistant Staphylococcus aureus among staff and pets in a small animal referral hospital in the UK

OBJECTIVES

The occurrence of methicillin-resistant Staphylococcus aureus (MRSA) and the possible relatedness between human and animal isolates were investigated among veterinary staff and hospitalized animals in a referral small animal hospital in the UK.

METHODS

A total of 300 swab samples were taken from nasal and oral mucosae of 78 veterinary staff, 45 dogs, 12 cats and from 30 environmental surfaces. Staphylococci were isolated by selective enrichment and characterized by biochemical tests and antimicrobial disc susceptibility testing. MRSA isolates were genotypically confirmed by PCR and typed by PFGE.

RESULTS

MRSA was isolated from 14 staff (17.9%), four dogs (9%), and three environmental sites (10%) yielding a total of 28 MRSA isolates. PFGE analysis revealed that most MRSA isolates were indistinguishable (56%) or closely related (26%) to EMRSA-15, one of the two epidemic MRSA strains dominant in UK hospitals. Like EMRSA-15, the predominant strain isolated from staff, dogs and environmental sites was resistant to fluoroquinolones in addition to all beta-lactams.

CONCLUSIONS

The study provides evidence of EMRSA-15 mucosal carriage in veterinary staff and hospitalized dogs, with the risk of MRSA carriage in veterinary staff being significantly higher than reported for the UK healthy community. EMRSA-15 was predominant in the hospital environment, including humans, dogs, and inanimate objects, but the mode by which the strain was introduced and spread remains uncertain.