Detection of Beta-Lactamase and Extended-Spectrum Beta-Lactamase of Pathogens Isolated from Pig and Chicken and Their Antibiotic Susceptibility Test

The antibacterial activity of beta-lactam antibiotics or their combinations with inhibitor sulbactum against non-lactamase- producing strains, lactamase-producing and ESBLs-producing isolates was evaluated with twofold dilution method after pathogens isolated from pigs and chickens were detected, respectively, for beta-lactamase and extended-spectrum beta- lactamases （ESBLs）, The results revealed that most of 43 clinically isolated strains could produce beta-lactamase and 3 strains of shigella isolated from chicken samples produced ESBLs. All of 30 lactamase-producing strains isolated and only one of 16 non-lactamase-producing strains were resistant to amoxicillin and ampicillin. MICs of ampicillin against lactamaseproducing isolates decreased 10-40 and 10-20 times respectively, when it was conbined with sulbactam at ration of 1：2 and 1：4. All clinical isolates were susceptible to third-generation cephalosporins. The MICs of third-generation cephalosporins against lactamase-producing isolates did not change when they were conbined with sulbactam. MICs of ceftiofur and ceftriaxone against ESBLs-producing isolates decreased 2-4 times when they were conbined with sulbactam.

Health care associated infections, antibiotic resistance and clinical outcome: A surveillance study from Sanandaj, Iran

AIM: To study the antibiotic susceptibility patterns of gram-negative healthcare associated bacterial infections at two tertiary hospitals in the Sanandaj city, Kurdistan Province, Iran.METHODS: From January 2012 to December 2012, all positive cultures from potentially sterile body fluids were gathered. They sent to professor Alborzi clinical microbiology center in Shiraz for further analysis and susceptibility testing. The antibiotic susceptibility was determined using the Kirby-Bauer method(disk diffusiontechnique). The Results were interpreted according to Clinical and Laboratory Standards Institute guidelines against a series of antimicrobials. World Health Organization definitions for Healthcare associated infections were followed.RESULTS: Seven hundred and thirty-two positive cultures were reported from both hospitals. Seventynine isolates/patients fulfilled the study criteria for healthcare associated gram-negative infections. The most frequent bacterial cultures were from the pediatric wards(52%). Serratia marcescens(S. marcescens)(38%) Escherichia coli(E. coli)(19%), Klebsiella pneumoniae(K. pneumoniae)(19%), Acinetobacter baumannii(6%), Enterobacter species(6%), Serratia odorifera(4%) and Pseudomonas species(5%) were the most frequently isolated organisms. The susceptibility pattern of common isolates i.e., S. marcescens, E. coli and K. pneumoniae for commonly used antibiotics were as follows: Ampicillin 3.3%, 6.7%, 20%; gentamicin 73.3%, 73.3%, 46.7%; ceftazidim 80%, 73.3%, 33.3%; cefepim 80%, 86.7%, 46.7%; piperacillin/tazobactam 90%, 66.7%, 86.7%; ciprofloxacin 100%, 73.3%, 86.7%; imipenem 100%, 100%, 100%, respectively. CONCLUSION: The most effective antibiotics against gram-negative healthcare associated infections are imipenem followed by ciprofloxacin. The resistance rate is high against ampicillin and cephalothin. The high mortality rate(46.1%) associated with S. marcescens is alarming.