Serovar determination, drug resistance patterns and plasmid profiles of Pseudomonas aeruginosa isolated from burn patients at two hospitals of Tehran (IRAN)

he serovars and drug susceptibility patterns of 265 isolates of Pseudomonas aeruginosa cultured from burn patients during 2001–2002 at Motahari and Tohid Hospital were determined. Distribution of serovars was different at two hospitals. Most of the isolates at Tohid Hospital belonged to serovar 0:1, but 21 and 13% of them were untypeable or polyagglutinable, respectively. Serovar 0:11 was the most prevalent serovar at Motahari Hospital. All the strains were multi resistant to tetracyclin, carbenicillin, amikacin, ceftazidime, sulfamethoxazol, ciprofloxacin, tobramycin, kanamycin, cefotaxime and gentamicin. Further analysis of the strains by plasmid profiling demonstrated that 95% of the isolates carried two megaplasmids. However, there was not any correlation between the serotyping and presence of plasmids. Changes in the drug susceptibility patterns and β-lactamase production of some cured derivatives were observed after the strains lost their plasmids. The emergence of multi-drug resistant strains of P. aeruginosa is a serious concern in burn patients who are hospitalized in Tehran.