RESUMO
Amp C beta-lactamases are cephalosporinases which hydrolyze cephamycins and are poorly inhibited by clavulanic acid. Amp C beta-lactamases confer resistance to a wide variety of antibiotics and pose both diagnostic and therapeutic challenges. The objective was to detect the frequency and antibiotic susceptibility pattern of Amp C beta-lactamase producing bacteria isolated from a tertiary care hospital of Pakistan. Organisms were isolated from various clinical specimens. First, the screening of the isolates was done by using cefoxitin disc. Screen-positive organisms were subjected to three dimensional extract test for detection of Amp C beta-lactamases. From a total of 100 organism tested, 64 organisms were positive on cefoxitin screen test. Out of these 64, 40 [62.5%] showed the presence of Amp C beta-lactamase. [E.coli n=18, K.pneumoniae n=14, K.oxytoca n=1, Enterobacter species n=5, Citrobacter freundii n=2] by three dimensional extract test. The antibiotics found out to show good activity against these resistant bacteria include meropenem and tigecycline. This is the first study to determine the frequency of Amp C beta lactamases from Pakistan. This study shows a high frequency of Amp C beta-lactamase producing isolates from a hospital, which may lead to serious therapeutic problems