Methicillin-Resistant Staphylococcus aureus (MRSA) Detected at Four U.S. Wastewater Treatment Plants

Background: The incidence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections is increasing in the United States, and it is possible that municipal wastewater could be a reservoir of this microorganism. To date, no U.S. studies have evaluated the occurrence of MRSA in wastewater.Objective: We examined the occurrence of MRSA and methicillin-susceptible S. aureus (MSSA) at U.S. wastewater treatment plants.Methods: We collected wastewater samples from two Mid-Atlantic and two Midwest wastewater treatment plants between October 2009 and October 2010. Samples were analyzed for MRSA and MSSA using membrane filtration. Isolates were confirmed using biochemical tests and PCR (polymerase chain reaction). Antimicrobial susceptibility testing was performed by Sensititre® microbroth dilution. Staphylococcal cassette chromosome mec (SCCmec) typing, Panton-Valentine leucocidin (PVL) screening, and pulsed field gel electrophoresis (PFGE) were performed to further characterize the strains. Data were analyzed by two-sample proportion tests and analysis of variance.Results: We detected MRSA (n = 240) and MSSA (n = 119) in 22 of 44 (50%) and 24 of 44 (55%) wastewater samples, respectively. The odds of samples being MRSA-positive decreased as treatment progressed: 10 of 12 (83%) influent samples were MRSA-positive, while only one of 12 (8%) effluent samples was MRSA-positive. Ninety-three percent and 29% of unique MRSA and MSSA isolates, respectively, were multidrug resistant. SCCmec types II and IV, the pvl gene, and USA types 100, 300, and 700 (PFGE strain types commonly found in the United States) were identified among the MRSA isolates.Conclusions: Our findings raise potential public health concerns for wastewater treatment plant workers and individuals exposed to reclaimed wastewater. Because of increasing use of reclaimed wastewater, further study is needed to evaluate the risk of exposure to antibiotic-resistant bacteria in treated wastewater.     

Methicillin-resistant Staphylococcus aureus ST30-SCCmec IVc clone as the major cause of community-acquired invasive infections in Argentina

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have become a major concern worldwide. We conducted a prospective multicenter study of invasive CA-MRSA to evaluate clinical features and genotype of strains causing invasive infections in Argentina. A total of 55 patients with invasive CA-MRSA infections were included. Most patients (60%) had bloodstream infections, 42% required admission to intensive care unit and 16% died. No CA-MRSA isolates were multiresistant (resistant ⩾3 classes of antibiotics). All isolates carried Panton-Valentine leukocidin (PVL) genes and staphylococcal cassette chromosome (SCCmec) type IV. The majority CA-MRSA strains belonged to ST30 and had identical pulsed-field gel electrophoresis (PFGE) patterns, qualifying as a clonal dissemination of a highly transmissible strain. The main clone recovered from patients with CA-MRSA invasive infections was genotyped as pulsed-field gel electrophoresis type C-ST30, SCCmec type IVc-spa type 019, PVL positive. It has become predominant and replaced the previously described CA-MRSA clone (PFGE type A, ST5, SCCmec type IV, spa type 311).     

Ceftaroline fosamil and treatment of acute bacterial skin and skin structure infections: CAPTURE study experience

Abstract

The Clinical Assessment Program and TEFLARO Utilization Registry (CAPTURE) is a multicentre retrospective cohort study in the USA describing treatment of acute bacterial skin and skin structure infection (ABSSSI) with ceftaroline fosamil (CPT-F). Charts for review were chosen by random selection. Among 647 evaluable patients, 52% were obese, 46% had diabetes mellitus (DM), and 19% had peripheral vascular disease (PVD). Methicillin-resistant Staphylococcus aureus (MRSA) was recovered in 28% and methicillin-susceptible S. aureus (MSSA), 11%. Antibiotics were administered prior to CPT-F treatment in 80%, and concurrently in 39%. Clinical success overall was 85%; in patients with DM, 83%; with PVD, 76%; and in obese patients, 88%. Clinical success was ≧ 79% across all infection types; 81% for MRSA and 83% for MSSA; and 86% for ceftaroline monotherapy and 84% for concurrent therapy. These high clinical success rates support CPT-F as an effective treatment option for ABSSSI, including infections due to MRSA and patients with significant co-morbidities.     

Staphylococcus aureus as source of catheter‐related bloodstream infection evaluated by PFGE and rep‐PCR typing in a Brazilian hospital

Staphylococci are a common cause of catheter‐related bloodstream infection (CR‐BSI), and epidemiological typing is an important tool for effective infection control. This study evaluated by PFGE and rep‐PCR whether Staphylococcus aureus strains isolated from skin and catheter tips were related to specimens isolated from blood. A prospective observational study, carried out in a clinical surgical ward at a Brazilian hospital between September 2000 and November 2002, investigated non‐tunneled central venous catheters from 179 patients. S. aureus isolates were mainly obtained from blood (41.4%), while coagulase‐negative staphylococci strains were more often isolated from the skin at the catheter insertion site (49.7%) and from the catheter tip (57.5%). Among the 21 strains isolated from 9 patients at 2 or 3 sites simultaneously, 9 were methicillin‐resistant S. aureus (MRSA) and 12 were methicillin‐susceptible S. aureus (MSSA). Seven patients harbored the same S. aureus strain isolated from the skin, blood and/or catheter tip cultures. MRSA isolates belonged to one PFGE pattern (type A‐ subtypes A₁, A₂ and A₃), and to two rep‐PCR patterns (a and b). MSSA isolates were distinguished in five PFGE (B to F) and in three rep‐PCR (c, d and e) patterns. Both PFGE and rep‐PCR methods indicated that the skin at the catheter insertion site was the origin of CR‐BSI caused by S. aureus.     

Necrotizing haemorrhagic pneumonia proves fatal in an immunocompetent child due to Panton–Valentine Leucocidin, toxic shock syndrome toxins 1 and 2 and enterotoxin C-producing Staphylococcus aureus

Panton–Valentine leucocidin (PVL) toxin-producing strains of Staphylococcus aureus ( S. aureus ) are associated with skin abscesses and furunculosis, with necrotizing pneumonia being a relatively rare problem. Here, we describe a fatal case of necrotizing pneumonia in a 14-year-old child who presented initially with sore throat and pyrexia. He deteriorated rapidly, developing hypotension, multiple organ failure and purpura fulminans. S. aureus was isolated from the tracheal aspirate, which was found to be positive for PVL, toxic shock syndrome toxins (TSST) 1 and 2 and staphylococcal enterotoxin C (SEC). It was postulated that purpura fulminans and toxic shock syndrome were a result of the abovementioned exotoxins.
Conclusion: This case highlights the emergence of PVL-positive community-acquired S. aureus infection and association of purpura fulminans with superantigens. Practitioners should be aware of this illness in order to initiate appropriate treatment.     

UK healthcare workers' knowledge of meticillin-resistant Staphylococcus aureus practice guidelines; a questionnaire study

Effective infection control practice requires knowledge of and adherence to contemporary infection control guidelines. Utilising a novel questionnaire tool, we evaluated knowledge of recently published guidelines on meticillin-resistant Staphylococcus aureus (MRSA) precautions in a number of relevant healthcare worker (HCW) populations. The questionnaire was developed from national UK MRSA practice guidelines and consisted of 10 ‘true or false’ statements. The questionnaire was utilised to assess knowledge in 293 participants from HCW and control populations. The participants included 188 doctors attending the British Medical Association's Annual Representatives Meeting, 52 trainee surgeons attending the Association of Surgeons in Training annual conference, 30 members of a non-clinical control population and 23 infection control nurses (ICNs). The mean (SD) score for knowledge levels obtained from doctors was 6.6 (1.68), for non-clinical control population was 4.7 (1.8) and for ICNs, 8.4 (1.12). There were significant differences in knowledge levels between different population groups (P < 0.001), UK employment region of the participant (P = 0.01) and the doctors' medical specialty (P = 0.02). Career seniority and gender of the participant were not significantly associated with differences in levels of knowledge. This questionnaire study evaluates a novel discriminatory questionnaire tool which differentiates knowledge levels of MRSA practice guidelines among a non-clinical population, HCWs and specialist infection control staff, thus providing a means for the rapid assessment of MRSA educational interventions. We identify demographics within HCW target populations which are associated with low levels of such knowledge. Consideration towards revising current HCW educational programmes to improve knowledge and best practice in MRSA prevention is required.