Intrafamilial spread of a Panton‐Valentine leukocidin‐positive community‐acquired methicillin‐resistant Staphylococcus aureus belonging to the paediatric clone ST5 SSCmecIV

Introduction: Community‐acquired methicillin‐resistant Staphylococcus aureus (CA‐MRSA) is increasingly recognized as an important pathogen. Panton–Valentine leukocidin (PVL)‐producing CA‐MRSA constitutes a public health concern because it can be responsible for severe, progressive necrotizing skin, soft‐tissue and pulmonary infections. Case presentation: We describe a case of recurrent transmission of PVL‐producing ST5, staphylococcal cassette chromosome mec type IV MRSA (paediatric clone) from an asymptomatic nasal carrier to his family causing severe skin and soft‐tissue infections in the mother and children. Nasal application of mupirocin in the carrier was successful for prevention of new infections. Conclusion: Recurrent skin infections are often not taken into account but may represent a serious threat if caused by a PVL‐producing MRSA strain. Family members of MRSA carriers are in danger of transmission. Characteristics of currently circulating CA‐MRSA strains require closer surveillance. Identification and decolonization of carriers is important to reduce the risk of spread into the community

Cross-sectional study on fecal carriage of Enterobacteriaceae with resistance to extended-spectrum cephalosporins in primary care patients

The aim of this study was to gain knowledge of the local epidemiology of extended-spectrum cephalosporin-resistant bacteria in primary care patients in a Swiss community. Fecal swabs were obtained from 291 primary care patients. Phenotyping and genotyping methods were used for further characterization of the isolates. Risk factors associated with carriage of ß-lactam-resistant strains were determined. Extended-spectrum cephalosporin-resistant Enterobacteriaceae were detected in 15 (5.2%) of the primary care patients. Thirteen isolates were CTX-M producers, one produced SHV-12, and three carried CMY-2. The pathogenic pandemic clone Escherichia coli ST131 was detected in 26.6% of the patients. Two patients (13.3%) carried two distinct strains simultaneously. There was a statistically significant risk of carriage of resistant strains for persons with a history of antibiotic therapy 4 months before sampling (p=0.05), markedly for therapy with ß-lactam (p=0.01). Age, gender, or history of hospitalization 4 months before sampling was not a risk factor for the acquisition of resistant bacteria in the analyzed patients. The relatively low prevalence of extended-spectrum cephalosporin-resistant strains in the community reflects the nationwide restrictive policy of antibiotic prescription as well as local implementation thereof. Nevertheless, our study shows that a potent antimicrobial resistance reservoir is present in primary care patients

Screening for fecal carriage of MCR-producing Enterobacteriaceae in healthy humans and primary care patients

Abstract Background The extent of the occurrence of the plasmid-encoded colistin resistance genes mcr-1 and mcr-2 among humans is currently sparsely studied in Western Europe. Objectives To determine the occurrence of MCR-producing Enterobacteriaceae in fecal samples of healthy humans with high occupational exposure to food and primary care patients in Switzerland. Methods Stool samples from 1091 healthy individuals and fecal swabs from 53 primary care patients were screened for polymyxin-resistant Enterobacteriaceae using LB agar containing 4 mg/L colistin. Minimal inhibitory concentrations (MICs) of colistin were determined for non-intrinsic colistin-resistant isolates. Isolates were screened by PCR for the presence of mcr-1 and mcr-2 genes. Results The fecal carriage rate of colistin resistant (MIC value >2 mg/l) Enterobacteriaceae was 1.5% for healthy people and 3.8% for primary care patients. Isolates included Hafnia alvei (n = 9), Escherichia coli (n = 3), Enterobacter cloacae (n = 4), Klebsiella pneumoniae (n = 1) and Raoultella ornithinolytica (n = 1). None of the isolates harbored the mcr-1 or mcr-2 genes. Conclusions There is no evidence for the presence of MCR-producers in the fecal flora of healthy people or primary care patients. Therefore, the risk of transfer of mcr genes from animals, food or the environment to humans is likely to be low in Switzerland