The Washing Machine as a Reservoir for Transmission of Extended-Spectrum-Beta-Lactamase (CTX-M-15)-Producing Klebsiella oxytoca ST201 to Newborns.

During the period from April 2012 to May 2013, 13 newborns (1 to 4 weeks of age) and 1 child in a pediatric hospital ward in Germany were colonized with Klebsiella oxytoca producing an extended-spectrum beta-lactamase (ESBL) (CTX-M-15). A microbiological source-tracking analysis with human and environmental samples was carried out to identify the source and transmission pathways of the K. oxytoca clone. In addition, different hygienic intervention methods were evaluated. K. oxytoca isolates were detected in the detergent drawer and on the rubber door seal of a domestic washer-extractor machine that was used in the same ward to wash laundry for the newborns, as well as in two sinks. These strains were typed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. The environmental findings were compared with those for the human strains and the isolates detected on clothing. The results from both techniques showed that the strains were identical (sequence type 201 and PFGE type 00531, a clone specific to this hospital and not previously isolated in Germany), emphasizing the washing machine as a reservoir and fomite for the transmission of these multidrug-resistant bacteria. After the washing machine was taken out of use, no further colonizations were detected during the subsequent 4-year period.IMPORTANCE Washing machines should be further investigated as possible sites for horizontal gene transfer (ESBL genes) and cross-contamination with clinically important Gram-negative strains. Particularly in the health care sector, the knowledge of possible (re-)contamination of laundry (patients' clothes and staff uniforms) with multidrug-resistant Gram-negative bacteria could help to prevent and to control nosocomial infections. This report describes an outbreak with a single strain of a multidrug-resistant bacterium (Klebsiella oxytoca sequence type 201) in a neonatal intensive care unit that was terminated only when the washing machine was removed. In addition, the study implies that changes in washing machine design and processing are required to prevent accumulation of residual water where microbial growth can occur and contaminate clothes.

Eradication of methicillin-resistant Staphylococcus aureus and of Enterobacteriaceae expressing extended-spectrum beta-lactamases on a model pig farm.

Colonization of livestock with bacteria resistant to antibiotics is considered a risk for the entry of drug-resistant pathogens into the food chain. For this reason, there is a need for novel concepts to address the eradication of drug-resistant commensals on farms. In the present report, we evaluated the decontamination measures taken on a farm contaminated with methicillin-resistant Staphylococcus aureus (MRSA) and Enterobacteriaceae expressing extended-spectrum ß-lactamases (ESBL-E). The decontamination process preceded the conversion from piglet breeding to gilt production. Microbiological surveillance showed that the decontamination measures eliminated the MRSA and ESBL-E strains that were detected on the farm before the complete removal of pigs, cleaning and disinfection of the stable, and construction of an additional stable meeting high-quality standards. After pig production was restarted, ESBL-E remained undetectable over 12 months, but MRSA was recovered from pigs and the environment within the first 2 days. However, spa (Staphylococcus aureus protein A gene) typing revealed acquisition of an MRSA strain (type t034) that had not been detected before decontamination. Interestingly, we observed that a farmworker who had been colonized with the prior MRSA strain (t2011) acquired the new strain (t034) after 2 months. In summary, this report demonstrates that decontamination protocols similar to those used here can lead to successful elimination of contaminating MRSA and ESBL-E in pigs and the stable environment. Nevertheless, decontamination protocols do not prevent the acquisition of new MRSA strains.

Analysis of Transmission of MRSA and ESBL-E among Pigs and Farm Personnel.

Livestock-associated bacteria with resistance to two or more antibiotic drug classes have heightened our awareness for the consequences of antibiotic consumption and spread of resistant bacterial strains in the veterinary field. In this study we assessed the prevalence of concomitant colonization with livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) and enterobacteriaceae expressing extended-spectrum betalactamases (ESBL-E) in farms at the German-Dutch border region. Nasal colonization of pigs with MRSA (113/547 (20.7%)) was less frequent than rectal colonization with ESBL-E (163/540 (30.2%)). On the individual farm level MRSA correlated with ESBL-E recovery. The data further provide information on prevalence at different stages of pig production, including abattoirs, as well as in air samples and humans living and working on the farms. Notably, MRSA was detected in stable air samples of 34 out of 35 pig farms, highlighting air as an important MRSA transmission reservoir. The majority of MRSA isolates, including those from humans, displayed tetracycline resistance and spa types t011 and t034 characteristic for LA-MRSA, demonstrating transmission from pigs to humans. ESBL-E positive air samples were detected on 6 out of 35 farms but no pig-to-human transmission was found. Detection of ESBL-E, e.g. mostly Escherichia coli with CTX-M-type ESBL, was limited to these six farms. Molecular typing revealed transmission of ESBL-E within the pig compartments; however, related strains were also found on unrelated farms. Although our data suggest that acquisition of MRSA and ESBL-E might occur among pigs in the abattoirs, MRSA and ESBL-E were not detected on the carcasses. Altogether, our data define stable air (MRSA), pig compartments (ESBL-E) and abattoir waiting areas (MRSA and ESBL-E) as major hot spots for transmission of MRSA and/or ESBL-E along the pig production chain.