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Recipients of allogeneic haematopoietic stem cell transplantation (allo-HSCT) are severely immunocompromised and are at increased risk of infection. In this prospective, observational, single-centre study including 110 allo-HSCT recipients, the rate of Staphylococcus aureus colonisation was reduced from 11.8% to 0% (P

OBJECTIVEIn-hospital transmission of methicillin-susceptibleStaphylococcus aureus(MSSA) among neonates remains enigmatic. We describe the epidemiology of MSSA colonization and infection in a 30-bed neonatal ward.DESIGNMultimodal outbreak investigationSETTINGA public 800-bed tertiary care university hospital in SwitzerlandMETHODSInvestigations in 2012–2013, triggered by a MSSA infection cluster, included prospective MSSA infection surveillance, microbiologic screening of neonates and environment, onsite observations, and a prospective cohort study. MSSA isolates were characterized by pulsed-field gel electrophoresis (PFGE) and selected isolates were examined for multilocus sequence type (MLST) and virulence factors.RESULTSAmong 726 in 2012, 30 (4.1%) patients suffered from MSSA infections including 8 (1.1%) with bacteremia. Among 655 admissions in 2013, 13 (2.0%) suffered from MSSA infections including 2 (0.3%) with bacteremia. Among 177 neonates screened forS. aureuscarriage, overall 77 (44%) tested positive. A predominant PFGE-1-ST30 strain was identified in 6 of 30 infected neonates (20%) and 30 of 77 colonized neonates (39%). This persistent clone waspvl-negative,tst-positive and belonged toagrgroup III. We found no environmental point source. MSSA carriage was associated with central vascular catheter use but not with a particular midwife, nurse, physician, or isolette. Observed healthcare worker behavior may have propagated transmission via hands and fomites. Despite multimodal interventions, clonal transmission and colonization continued and another clone, PFGE-6-ST5, became predominant.CONCLUSIONSHospital-acquired MSSA clones represent a high proportion of MSSA colonization but not MSSA infections in neonate inpatients. In contrast to persisting MSSA, transmission infection rates decreased concurrently with interventions. It remains to be established whether eradication of hospital-acquired MSSA strains would reduce infection rates further.Infect. Control Hosp. Epidemiol.2015;36(11):1305–1312

Background Methicillin-resistant Staphylococcus aureus (MRSA) is a global epidemic threat. The aim of this study was to determine which globally known MRSA lineages are currently present at our tertiary care hospital in Switzerland, a hospital with low MRSA prevalence. In light of the increasing prevalence of multi drug resistance including vancomycin resistance we also assessed antibiotic susceptibilities. Methods The 146 MRSA strains collected over two years (March 2012 until February 2014) at the University Hospital Zurich, Switzerland, were analyzed by PFGE analysis of SmaI digests in combination with spa-typing. In addition, representative isolates were analyzed by multi locus sequence typing (MLST). Susceptibilities to eight antibiotics were assessed using the Kirby-Bauer disc diffusion method. Results Isolates showed resistance to erythromycin (48%), ciprofloxacin (43%), clindamycin (31%), tetracycline (22%), and gentamicin (16%). All isolates were susceptible to vancomycin, 95% were susceptible to sulfamethoxazole/trimethoprim and rifampicin, respectively. PFGE analysis revealed 22 different patterns, with four major patterns that accounted for 53.4% of all MRSA isolates, and seven sporadic patterns. Spa typing revealed 50 different spa types with the predominant types being t008 (14%), t002 (10%), and t127 (9%). 82% of the MRSA isolates could be assigned to six clonal complexes (CCs) namely CC1 (10%), CC5 (23%), CC8 (18%), CC22 (17%), CC30 (11%), and CC45 (3%) based on spa-types, PFGE patterns, and MLST. Two isolates could not be typed by either PFGE analysis or spa-typing and three isolates had spa-types that have not yet been described. Conclusions The combination of the two typing methods was more discriminatory as compared to the use of a single method. Several of the lineages that are predominant in Europe are present in our hospital. Resistances to antibiotics have decreased in comparison to a study conducted between 2004 and 2006. Electronic supplementary material The online version of this article (doi:10.1186/s12941-015-0075-3) contains supplementary material, which is available to authorized users.

USA300 methicillin-resistant Staphylococcus aureus (MRSA) is the most prevalent MRSA in the United States of America (USA) and a global epidemic threat. We investigated the prevalence of USA300 at a tertiary care hospital in Zurich, Switzerland, where all MRSA strains have been collected and PFGE typed since 1992. These strains were retrospectively compared to the PFGE pattern of USA300 strain JE2. Isolates with a respective PFGE pattern were spa-typed and tested for the presence of the arginine catabolic mobile element (ACME) arc gene cluster and Panton-Valentine Leucocidin (PVL) genes. The first MRSA strain with a USA300 PFGE pattern was isolated in 2001 from a patient visiting from the USA. USA300 strains represented between 0% (in 2002) and 9.2% (in 2012) of all MRSA isolates in our hospital. We identified various USA300 subtypes based on either the PFGE pattern, the spa-type or absence of either the PVL genes or ACME arc gene cluster. All the USA300 strains including the variants (n=47) accounted for 5.6% of all MRSA isolates typed between 2001 and 2013 and reached a maximum of 14.5% in 2009. They predominantly caused skin and soft tissue infections (74.4%). In conclusion, even though USA300 has been present in our hospital for over twelve years it has not become the predominant MRSA clone like in the USA. However, in light of the global burden of USA300, care must be taken to further contain the spread of this lineage and of MRSA in general in our hospital.

Hematopoietic cell transplant (HCT) recipients are at increased risk for infections. Staphylococcus aureus (SA) colonizes 20-50% of healthy individuals and is a risk factor for subsequent invasive SA infections. Colonization rates in patients undergoing allogeneic HCT and clinical relevance for the time of aplasia and severely reduced immune function following HCT are not known. Only some retrospective data on methicillin-resistant SA infection rates are available. In this study, we prospectively assessed the prevalence of SA colonization in 110 consecutive patients before and during allo-HCT in a single-center observational study from June 2013 to January 2016. All patients undergoing allo-HCT were screened for nasal, pharyngeal and inguinal SA colonization weekly beginning at the time of admission to the transplant unit until neutrophil recovery. After swabs for the initial SA screening were taken all patients were put on oral gentamicin and vancomycin for gut decontamination until neutrophils had recovered. Quantitative stool analyses were performed weekly. In case of fever or increased of inflammatory laboratory parameters (C-reactive protein) blood cultures were drawn. In our cohort we found a SA prevalence of 14.5% (16/110 patients) at the time of admission to the transplant unit. All SA strains detected were sensitive to methicillin. Most patients colonized with SA in the nose (13/16), while pharyngeal and inguinal colonization was found less frequently (n=5 and n=6, respectively). Patients aged 60-67 years (n=14) showed the highest SA carrier rate (5/14, 36%, RR=1.36, p=0.02). There was no correlation between SA colonization and sex, underlying disease or chemotherapeutic pretreatment. Prior systemic antibiotic treatments using SA effective drugs within six months before admission to the transplant unit did not have relevant impact on SA prevalence at the time of screening. Within the group of the 16 SA-positive patients there were 2 patients (12.5%) who had received oral antibiotic gut decontamination (vancomycin and /or gentamicin) within twelve weeks prior to admission (during induction chemotherapy). In the SA negative group a similar proportion of patients had received oral gut decontamination (12/94; 12.8%). Despite the severe immunosuppression and skin and mucosal lesions incl. indwelling catheters no systemic SA infections (including bacteremia) were found during hospitalization in any of the HCT patients. All SA positive patients became SA negative within three weeks. These observations imply that decolonization is achieved by the consistent oral gut decontamination that all patients received in conjunction with the antibacterial soaps used. In conclusion, the SA colonization prevalence in our cohort of patients undergoing allogeneic HCT was 14.5% which is lower than described previously in the literature. Of note, our cohort did not comprise patients with MRSA. Here, we demonstrate in a prospective study that oral gut decontamination with vancomycin and gentamicin in addition to strict hygiene measures resulted in eradication of SA colonization in all 16 colonized patients within three weeks. Disclosures No relevant conflicts of interest to declare.