PCR Identification and Automated Ribotyping of Pseudomonas aeruginosa Clinical Isolates from Intensive Care Patients

Nosocomial isolates of Pseudomonas aeruginosa exhibit high rates of resistance to antibiotics, and are often multidrug resistant. P. aeruginosa clinical isolates (n=56) were obtained from ICU patients in a hospital in Pakistan over a 3-y period. Antimicrobial susceptibility of the 56 P. aeruginosa clinical isolates was investigated using 7 antibiotics and the resistance rates were as follows: aztreonam (68% resistant), ceftazidime (67%), imipenem (66%), ofloxacin (59%), amikacin (56%), gentamicin (44%), and piperacillin-tazobactam (27%) (p<0.01). In addition, 55% of the P. aeruginosa clinical isolates were resistant to 4 or more antibiotics. Imipenem-resistant strains were frequently associated with ceftazidime, ofloxacin, aztreonam, and more strikingly, amikacin resistance (p<0.05). PCR (using P. aeruginosa-specific primers VIC1+VIC2 and P1+P2, respectively) was highly specific and sensitive, and was positive for all 56 P. aeruginosa isolates tested. Automated ribotyping was used to investigate the clona...