Performance of Oxoid Brilliance™ MRSA medium for detection of methicillin-resistant Staphylococcus aureus: an in vitro study

Oxoid Brilliance™ MRSA was evaluated for its ability to identify methicillin-resistant Staphylococcus aureus. A well-defined collection of staphylococci was used (n = 788). After 20 h incubation, the sensitivity was 99.6% and the specificity was 97.3%. This new medium is a highly sensitive method of screening for MRSA

Spread of a methicillin-resistant Staphylococcus aureus ST80 strain in the community of the northern Netherlands

Infections caused by community-acquired methicillin-resistant Staphylococcus aureus (MRSA) are emerging as a major public health problem. In this study, we describe the distribution of 54 Panton-Valentine leucocidin (PVL)-carrying MRSA isolates in the northern Netherlands between 1998 and 2005, of which 43 (80%) consisted of the European PVL-positive strain multi locus sequence type 80 with staphylococcal cassette chromosome mec type IVc (ST80). Individual cases and small clusters of ST80 predominated in the community (74%), but ST80 was also found in nursing homes (16%) and hospitals (9%). Long-term carriership (months to years) and reinfection of patients with ST80 has probably led to the strain spreading in the community and subsequently to further migration to health care environments

Multidrug resistant Acinetobacter baumannii: a descriptive study in a city hospital

<p>Abstract</p> <p>Background</p> <p>Multidrug resistant <it>Acinetobacter baumannii</it>, (MRAB) is an important cause of hospital acquired infection. The purpose of this study is to determine the risk factors for MRAB in a city hospital patient population.</p> <p>Methods</p> <p>This study is a retrospective review of a city hospital epidemiology data base and includes 247 isolates of Acinetobacter baumannii (AB) from 164 patients. Multidrug resistant <it>Acinetobacter baumannii </it>was defined as resistance to more than three classes of antibiotics. Using the non-MRAB isolates as the control group, the risk factors for the acquisition of MRAB were determined.</p> <p>Results</p> <p>Of the 247 AB isolates 72% (177) were multidrug resistant. Fifty-eight percent (143/247) of isolates were highly resistant (resistant to imipenem, amikacin, and ampicillin-sulbactam). Of the 37 patients who died with Acinetobacter colonization/infection, 32 (86%) patients had the organism recovered from the respiratory tract. The factors which were found to be significantly associated (p ≤ 0.05) with multidrug resistance include the recovery of AB from multiple sites, mechanical ventilation, previous antibiotic exposure, and the presence of neurologic impairment. Multidrug resistant Acinetobacter was associated with significant mortality when compared with sensitive strains (p ≤ 0.01). When surgical patients (N = 75) were considered separately, mechanical ventilation and multiple isolates remained the factors significantly associated with the development of multidrug resistant Acinetobacter. Among surgical patients 46/75 (61%) grew a multidrug resistant strain of AB and 37/75 (40%) were resistant to all commonly used antibiotics including aminoglycosides, cephalosporins, carbepenems, extended spectrum penicillins, and quinolones. Thirty-five percent of the surgical patients had AB cultured from multiple sites and 57% of the Acinetobacter isolates were associated with a co-infecting organism, usually a Staphylococcus or Pseudomonas. As in medical patients, the isolation of Acinetobacter from multiple sites and the need for mechanical ventilation were significantly associated with the development of MRAB.</p> <p>Conclusions</p> <p>The factors significantly associated with MRAB in both the general patient population and surgical patients were mechanical ventilation and the recovery of Acinetobacter from multiple anatomic sites. Previous antibiotic use and neurologic impairment were significant factors in medical patients. Colonization or infection with MRAB is associated with increased mortality.</p

[18F]FDG-6-P as a novel in vivo tool for imaging staphylococcal infections

Background Management of infection is a major clinical problem. Staphylococcus aureus is a Gram-positive bacterium which colonises approximately one third of the adult human population. Staphylococcal infections can be life-threatening and are frequently complicated by multi-antibiotic resistant strains including methicillin-resistant S. aureus (MRSA). Fluorodeoxyglucose ([18F]FDG) imaging has been used to identify infection sites; however, it is unable to distinguish between sterile inflammation and bacterial load. We have modified [18F]FDG by phosphorylation, producing [18F]FDG-6-P to facilitate specific uptake and accumulation by S. aureus through hexose phosphate transporters, which are not present in mammalian cell membranes. This approach leads to the specific uptake of the radiopharmaceutical into the bacteria and not the sites of sterile inflammation. Methods [18F]FDG-6-P was synthesised from [18F]FDG. Yield, purity and stability were confirmed by RP-HPLC and iTLC. The specificity of [18F]FDG-6-P for the bacterial universal hexose phosphate transporter (UHPT) was confirmed with S. aureus and mammalian cell assays in vitro. Whole body biodistribution and accumulation of [18F]FDG-6-P at the sites of bioluminescent staphylococcal infection were established in a murine foreign body infection model. Results In vitro validation assays demonstrated that [18F]FDG-6-P was stable and specifically transported into S. aureus but not mammalian cells. [18F]FDG-6-P was elevated at the sites of S. aureus infection in vivo compared to uninfected controls; however, the increase in signal was not significant and unexpectedly, the whole-body biodistribution of [18F]FDG-6-P was similar to that of [18F]FDG. Conclusions Despite conclusive in vitro validation, [18F]FDG-6-P did not behave as predicted in vivo. However at the site of known infection, [18F]FDG-6-P levels were elevated compared with uninfected controls, providing a higher signal-to-noise ratio. The bacterial UHPT can transport hexose phosphates other than glucose, and therefore alternative sugars may show differential biodistribution and provide a means for specific bacterial detection

The use of spa and phage typing for characterization of clinical isolates of methicillin-resistant Staphylococcus aureus in the University Clinical Center in Gdańsk, Poland

The emergence of spa types and spa–clonal complexes (CC) among clinical methicillin-resistant Staphylococcus aureus isolates collected from the University Clinical Center in Gdańsk between 2008 and 2009 were investigated. Phage typing was used as the initial screening in the study. The basic set of phages and the additional set of phages were used. Most of the isolates (56 %) belonged to the phage group III. With the additional set of phages, eight types were found, with predominant one MR8 (50 %). Sixteen distinct spa types were observed. The most frequent were t003 (22 %), t151 (16 %), and t008 (12 %). The spa types were clustered into two spa-CC and eight singletons. The predominant CC010 (50 %) consisted of six types, with the most common t003 (36.7 %) and t151(26.7 %), and in 80 % was identified as staphylococcal chromosomal casette mec (SCCmec) type II. The second cluster has no founder (12 %) with only two spa types: t037 belonging to SCCmec type III and t029. In the most frequent singleton, spa type t008 alone was clustered in 12 % of the isolates. All singletons correspond to SCCmec type IV. The CC010 was distributed in most of the hospital wards, corresponded to Multilocus sequence typing type ST5/ST225 and was constantly present throughout the observed period. The isolates of CC010 generally belonged to the phage group III, and most of them (53.3 %) were resistant to erythromycin, clindamycin, and ciprofloxacin. The concordance between spa-clone and phage type was very high, but the same phage type MR8 was observed within different spa types of the predominant clone

The epidemiology and transmission of methicillin-resistant Staphylococcus aureus in the community in Singapore: study protocol for a longitudinal household study.

BACKGROUND/AIM: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common multidrug-resistant organisms in healthcare settings worldwide, but little is known about MRSA transmission outside of acute healthcare settings especially in Asia. We describe the methods for a prospective longitudinal study of MRSA prevalence and transmission. METHODS: MRSA-colonized individuals were identified from MRSA admission screening at two tertiary hospitals and recruited together with their household contacts. Participants submitted self-collected nasal, axilla and groin (NAG) swabs by mail for MRSA culture at baseline and monthly thereafter for 6 months. A comparison group of households of MRSA-negative patients provided swab samples at one time point. In a validation sub-study, separate swabs from each site were collected from randomly selected individuals, to compare MRSA detection rates between swab sites, and between samples collected by participants versus those collected by trained research staff. Information on each participant's demographic information, medical status and medical history, past healthcare facilities usage and contacts, and personal interactions with others were collected using a self-administered questionnaire. DISCUSSION/CONCLUSION: Understanding the dynamics of MRSA persistence and transmission in the community is crucial to devising and evaluating successful MRSA control strategies. Close contact with MRSA colonized patients may to be important for MRSA persistence in the community; evidence from this study on the extent of community MRSA could inform the development of household- or community-based interventions to reduce MRSA colonization of close contacts and subsequent re-introduction of MRSA into healthcare settings. Analysis of longitudinal data using whole-genome sequencing will yield further information regarding MRSA transmission within households, with significant implications for MRSA infection control outside acute hospital settings

Toward New Therapeutics for Skin and Soft Tissue Infections: Propargyl-Linked Antifolates Are Potent Inhibitors of MRSA and Streptococcus pyogenes

Hospital- and community-acquired, complicated skin and soft tissue infections, often attributed to Staphylococcus aureus and Streptococcus pyogenes, present a significant health burden that is associated with increased health care costs and mortality. As these two species are difficult to discern on diagnosis and are associated with differential profiles of drug resistance, the development of an efficacious antibacterial agent that targets both organisms is a high priority. Herein we describe a structure-based drug development effort that has produced highly potent inhibitors of dihydrofolate reductase from both species. Optimized propargyl-linked antifolates containing a key pyridyl substituent display antibacterial activity against both methicillin-resistant S. aureus and S. pyogenes at MIC values below 0.1 µg/mL and minimal cytotoxicity against mammalian cells. Further evaluation against a panel of clinical isolates shows good efficacy against a range of important phenotypes such as hospital- and community-acquired strains as well as strains resistant to vancomycin