Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/7/2012
Publication Date: 7/9/2012
Citation: Huang, X., Frye, J.G., Chahine, M.A., Glenn, L.M., Ake, J.A., Su, W., Nikolich, M.P., Lesho, E.P. 2012. Characteristics of plasmids in multi-drug-resistant enterobacteriaceae isolated during prospective surveillance of a newly opened hospital in Iraq. PLoS One. 7(7):1-8.e40360. doi: 10.1371/journal.pone.0040360. Interpretive Summary: Escherichia coli and Klebsiella spp. are increasingly common bacterial cause of infections in hospitals worldwide. These bacteria can often be multidrug-resistant (MDR) thus making treatment difficult. Small, circular pieces of extra-chromosomal DNA called plasmids are thought to carry antibiotic resistance in these bacteria. In this study, 38 MDR and 41 non-MDR bacterial strains isolated by U.S. Navy medical staff in Iraq from patients, healthcare workers, and environmental surfaces in a newly opened hospital were investigated to determine if plasmids were associated with antimicrobial resistances. MDR E. coli and K. pneumonia isolates contained more equal to 3 plasmids compared to their non-MDR counterparts, which carried less than 2 plasmids (p <0.01). Sixteen plasmids from 13 of the MDR isolates were moved into non-resistant bacteria, causing them to become resistant to antibiotics and demonstrating that the plasmids encoded MDR. Microarray analysis of these plasmids found they were carrying multiple resistance genes. Genetic transfer genes were also detected on the plasmids from both MDR and non-MDR isolates. Seven different types of plasmids were also identified in the isolates. This is the first characterization of plasmids found in MDR bacteria compared to their susceptible counterparts from a healthcare setting in Iraq. This data sets a reference point for understanding MDR spread in these hospitals and can be used to help develop interventions and infection control measures to prevent MDR human disease.
Technical Abstract: Multidrug-resistant (MDR) bacteria such as Escherichia coli and Klebsiella spp. are increasingly common causes of infections in hospitals worldwide and also in the U.S. military treatment facilities. Plasmids are thought to play an important role in the dissemination of antibiotic resistance in these bacteria. In this study, 38 MDR and 41 non-MDR Enterobacteriaceae strains isolated from patients, healthcare workers, and environmental surfaces located in a newly opened hospital in Iraq in 2008 were investigated to determine the impact of plasmid mediated drug resistance on the isolates. Our results demonstrated that MDR E. coli and K. pneumonia isolates harbored significantly more equal to 3 plasmids compared to their non-MDR counterparts, which carried less than 2 plasmids (p <0.01). Sixteen plasmids from 13 representative MDR Enterobacteriaceae isolates were analyzed by transformation and found to confer resistance to 3 or more classes of antibiotics. Various large plasmids (>70kb) from these isolates were confirmed as carrying multiple resistance genes by DNA microarray analysis. Aminoglosides (acc, aadA, aph, strA/B,ksgA), ß-lactams (tem1, ampC, ctx-m-15, oxa-1, vim-2 and shv), sulfamethoxazole/trimethoprim, tetracycline, and chloramphenical resistance genes were detected on these plasmids. Multiple plasmid carrying antibiotic resistance genes were found in the same host strain. Genetic transfer-associated genes were identified on the plasmids from both MDR and non-MDR isolates. Seven plasmid replicon types, FII, FIA, FIB, B/O, K, I1 and N were identified in the isolates. This is the first report of the characteristics of the plasmids found in Enterobacteriaceae compared to their susceptible counterparts isolated from an entire healthcare setting (patients, providers, and the environment) in Iraq.