Characteristics of plasmids in multi-drug-resistant Enterobacteriaceae isolated during prospective surveillance of a newly opened hospital in Iraq.
BACKGROUND
Gram-negative multidrug-resistant (MDR) bacteria are major causes of nosocomial infections, and antibiotic resistance in these organisms is often plasmid mediated. Data are scarce pertaining to molecular mechanisms of antibiotic resistance in resource constrained areas such as Iraq.


RESULTS
In this study, all MDR Enterobacteriaceae (n = 38) and randomly selected non-MDR counterparts (n = 41) isolated from patients, healthcare workers and environmental surfaces in a newly opened hospital in Iraq were investigated to characterize plasmids found in these isolates and determine their contribution to antibiotic resistance. Our results demonstrated that MDR E. coli and K. pneumoniae isolates harbored significantly more (≥ 3) plasmids compared to their non-MDR counterparts, which carried ≤ 2 plasmids (p<0.01). Various large plasmids (~52 to 100 kb) from representative isolates were confirmed to contain multiple resistance genes by DNA microarray analysis. Aminoglycoside (acc, aadA, aph, strA/B, and ksgA), β-lactam (bla(TEM1), bla(AMPC), bla(CTX-M-15), bla(OXA-1), bla(VIM-2) and bla(SHV)), sulfamethoxazole/trimethoprim (sul/dfr), tetracycline (tet) and chloramphenicol (cat) resistance genes were detected on these plasmids. Additionally, multiple plasmids carrying multiple 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 detected in the isolates, while globally disseminated IncA/C and IncHI1 plasmids were not detected in these isolates.


CONCLUSIONS
This is the first report of the characteristics of the plasmids found in Enterobacteriaceae isolated following the opening of a new hospital in Iraq. The information provided here furthers our understanding of the mechanisms of drug resistance in this specific region and their evolutionary relationship with other parts of world. The large plasmids, carrying resistance genes and transfer-associated genes, may be potential factors for regional dissemination of antibiotic resistance.
Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America. xiaozhe.huang1.ctr@us.army.mil
Xiao-Zhe
XZ
Huang
Jonathan G
JG
Frye
Mohamad A
MA
Chahine
Lashanda M
LM
Glenn
Julie A
JA
Ake
Wanwen
W
Su
Mikeljon P
MP
Nikolich
Emil P
EP
Lesho
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects / Q000235:genetics*; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology; D005798:Genes, Bacterial / Q000235:genetics; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D007493:Iraq / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D020411:Oligonucleotide Array Sequence Analysis; D010957:Plasmids / Q000235:genetics*; D011159:Population Surveillance; D011446:Prospective Studies; D012093:Replicon / Q000235:genetics; D014170:Transformation, Genetic
D000900:Anti-Bacterial Agents