Jornal de Patologia Clínica e Experimental

Abstrato

Isolation of a Novel Antibiotic Resistance Plasmid DNA from Hospital Isolates of Pseudomonas aeruginosa

Erfaneh Jafari, Mohammad Reza Shakibaie and Leila Poormasoomi

Emergence and dissemination of antibiotic resistance plasmids are major concern for hospital care system and increases the cost and decreases effectiveness of available antibiotics used in treatment of hospitalized patients. In this study two Pseudomonas aeruginosa, two Escherichia coli, and a Klebsiella pneumoniae were isolated from Intensive Care Unit (ICU) of a university hospital, in Kerman, Iran. K. pneumoniae exhibited resistance to all antibiotics routinely used in our hospital for treatment of patients except meropenem, while, the other isolates were sensitive to carbapenems and ciprofloxacin. Plasmid analysis of the selected isolates showed the presence of a single plasmid with molecular weight 65Kb in the P. aeruginosa isolate1. The plasmid was named as pKUM and belonged to incompatibility group -2 (IncP-2). Conjugation by filter mating revealed that resistance associated with gentamicin, kanamycin, cefotaxime, and ceftazidime phenotypes were transferred to E. coli ATCC25922 (Rifr) recipient cells at the frequencies of 3.13 × 10-5 and 5.3 ×10-7 respectively. The results were further supported by curing and transformation experiments. MIC to cefepime was ≥30 μg/mL both in donor as well as the transconjugants while decreased to 0.5μg/ mL in cured derivative. The plasmid pKUM was quite stable (86%) in both donor cells and the recipient. From above results we concluded that resistances to third generation of cephalosporins, aminoglycosides and cefepime in P. aeruginosa isolate1 were indeed encoded by a conjugative plasmid. Acquisition of cefepime resistance through plasmid complicates the therapy of neutropenic patients in ICU and increases the cost and mortality of these patients.