Molecular Dissection of an Outbreak of Carbapenem-Resistant Enterobacteriaceae Reveals Intergenus KPC Carbapenemase Transmission through a Promiscuous Plasmid

Carbapenem-resistant Enterobacteriaceae (CRE) have emerged as major causes of health care-associated infections worldwide. This diverse collection of organisms with various resistance mechanisms is associated with increased lengths of hospitalization, costs of care, morbidity, and mortality. The global spread of CRE has largely been attributed to dissemination of a dominant strain of Klebsiella pneumoniae producing a serine β-lactamase, termed K. pneumoniae carbapenemase (KPC). Here we report an outbreak of KPC-producing CRE infections in which the degree of horizontal transmission between strains and species of a promiscuous plasmid is unprecedented. Sixteen isolates, comprising 11 unique strains, 6 species, and 4 genera of bacteria, were obtained from 14 patients over the first 8 months of the outbreak. Of the 11 unique strains, 9 harbored the same highly promiscuous plasmid carrying the KPC gene blaKPC. The remaining strains harbored distinct blaKPC plasmids, one of which was carried in a strain of Klebsiella oxytoca coisolated from the index patient and the other generated from transposition of the blaKPC element Tn4401. All isolates could be genetically traced to the index patient. Molecular epidemiological investigation of the outbreak was aided by the adaptation of nested arbitrary PCR (ARB-PCR) for rapid plasmid identification. This detailed molecular genetic analysis, combined with traditional epidemiological investigation, provides insights into the highly fluid dynamics of drug resistance transmission during the outbreak

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Brookhaven National Laboratory [operated by] Associated Universities Inc. under contract with the U.S. Atomic Energy Commission."Physics--TID-4500, 32nd Ed."Includes bibliographical references.Mode of access: Internet

Extended-spectrum and CMY-type beta-lactamase-producing Escherichia coli in clinical samples and retail meat from Pittsburgh, USA and Seville, Spain

Infections due to Escherichia coli producing extended-spectrum beta-lactamase (ESBL) or CMY-type beta-lactamase (CMY) are increasingly observed in non-hospitalized patients. The origin of these organisms is uncertain, but retail meat contaminated with E. coli may be a source. In the present study, clinical information and strains collected from patients infected or colonized with ESBL-producing and CMY-producing E. coli at hospitals in Pittsburgh, USA and Seville, Spain were investigated. Retail meat purchased in these cities was also studied for the presence of these organisms. Twenty-five and 79 clinical cases with ESBL-producing E. coli and 22 cases and one case with CMY-producing E. coli were identified in Pittsburgh and Seville, respectively. Among them all, community-acquired and healthcare-associated cases together constituted 60% of the cases in Pittsburgh and 73% in Seville. Community-acquired cases were more common in Seville than in Pittsburgh (49% vs. 13%; p < 0.001). ESBL-producing and CMY-producing E. coli isolates were commonly recovered from the local retail meat. In particular, 67% (8/12) of retail chickens in Seville and 85% (17/20) of those in Pittsburgh contained ESBL-producing and CMY-producing E. coli isolates, respectively. Among the ESBL-producing isolates, CTX-M and SHV were the most common ESBL types in both clinical and meat isolates. Approximately half of the ESBL-producing and CMY-producing E. coli isolates from meat belonged to phylogenetic groups associated with virulent extra-intestinal infections in humans. Community and healthcare environments are now significant reservoirs of ESBL-producing and CMY-producing E. coli. Retail meat is a potential source of these organisms

Colonization of residents and staff of a long-term-care facility and adjacent acute-care hospital geriatric unit by multiresistant bacteria

Long-term-care facilities (LTCFs) are reservoirs of resistant bacteria. We undertook a point-prevalence survey and risk factor analysis for specific resistance types among residents and staff of a Bolzano LTCF and among geriatric unit patients in the associated acute-care hospital. Urine samples and rectal, inguinal, oropharyngeal and nasal swabs were plated on chromogenic agar; isolates were typed by pulsed-field gel electrophoresis; resistance genes and links to insertion sequences were sought by PCR; plasmids were analysed by PCR, restriction fragment length polymorphism and incompatibility grouping. Demographic data were collected. Of the LTCF residents, 74.8% were colonized with =1 resistant organism, 64% with extended-spectrum ß-lactamase (ESBL) producers, 38.7% with methicillin-resistant Staphylococcus aureus (MRSA), 6.3% with metallo-ß-lactamase (MBL) producers, and 2.7% with vancomycin-resistant enterococci. Corresponding rates for LTCF staff were 27.5%, 14.5%, 14.5%, 1.5% and 0%, respectively. Colonization frequencies for geriatric unit patients were lower than for those in the LTCF. Both clonal spread and plasmid transfer were implicated in the dissemination of MBL producers that harboured IncN plasmids bearing blaVIM-1, qnrS, and blaSHV-12. Most (44/45) ESBL-producing Escherichia coli isolates had blaCTX-M genes of group 1; a few had blaCTX-M genes of group 9 or blaSHV-5; those with blaCTX-M-15 or blaSHV-5 were clonal. Risk factors for colonization of LTCF residents with resistant bacteria included age =86 years, antibiotic treatment in the previous 3 months, indwelling devices, chronic obstructive pulmonary disease, physical disability, and the particular LTCF unit; those for geriatric unit patients were age and dementia. In conclusion, ESBL-producing and MBL-producing Enterobacteriaceae and MRSA were prevalent among the LTCF residents and staff, but less so in the hospital geriatric unit. Education of LTCF employees and better infection control are proposed to minimize the spread of resistant bacteria in the facility