IN-VITRO ACTIVITY OF PIPERACILLIN TAZOBACTAM VERSUS OTHER BROAD-SPECTRUM ANTIBIOTICS AGAINST NOSOCOMIAL GRAM-NEGATIVE PATHOGENS ISOLATED FROM BURN PATIENTS/

Burn patients are at high risk for nosocomial infections due to multir esistant bacteria, a large proportion of which are Gram-negative. Tazo bactam, a potent inhibitor of beta pi-lactamases, extends the spectrum of piperacillin to include many beta-lactamase producing bacteria. Co nsequently, it was decided to evaluate the activity of piperacillin/ta zobactam in comparison with that of eight other antibiotics that are u sually used for therapy against Gram-negative bacterial infections in our burn unit. All consecutive Gram-negative isolates from wounds, blo od, respiratory tract, urine etc. from burn patients considered to be clinically significant were tested for their susceptibility to piperac illin/tazobactam, piperacillin, ceftazidime, cefotaxime, ceftriaxone, ciprofloxacin, gentamicin, amikacin and imipenem, determined by disk d iffusion test. The zone inhibition was interpreted according to NCCLS recommendations. A total of 948 strains, isolated during the period of July, 1994 to September, 1995, made up of Pseudomonas spp (326), Acin etobacter spp (268) and Enterobacteriaceae (354), were tested. Overall piperacillin/tazobactam showed superior activity over the other antib iotics except for imipenem. Of the 948 isolates, 87% were susceptible to the combination, 56% to the three third generation cephalosporins, 69% to ciprofloxacin, 59% to the aminoglycosides and 97% to imipenem. Piperacillin/tazobactam showed strikingly superior activity over piper acillin alone against Acinetobacter spp followed by Entero-bacteriacea e and the least against Pseudomonas. The emergence of Acinetobacter sp p as a dominant Gram-negative pathogen in burn patients and its high l evel of resistance against most of the antibiotics tested except piper acillin/tazobactam (87%) and imipenem (100%) were significant in light of the epidemiology of burn infections and treatment. This study sugg ests that piperacillin/tazobactam holds good promise against Gram-nega tive infections in burn patients.