| Objective To characterize the epidemiology of etiologic factors and drug tolerance of the Intra-abdoninal infections and to acquire the information about the incidence of ESBLs and/or AmpC enzyme of Enterobacter cloacae (E.cloacae) and Pseudomonas aeruginosa (Ps aeruginosa) in First affiliated Hospital of Anhui Medical University and to instruct rational application of antibiotics clinically. Methods This retrospective study investigated 165 patients admitted in internal ward between 1975-1999 and 218 patients admitted in surgery ward between 1996-2000 of intra-abdominal infections: comparison of distribution of pathogenic bacteria in different ages and analysis of drug tolerance. 100 multi-drug resistant clinical isolates of Ps aeruginosa and E.cloacae were collected from infectious specimens of sputum, urine, peritoneal fluid, etc of the whole hospital patients during the period of 1999-2001. To establish a simple and quick Kirby-Bauer(K-B) test, which can detect AmpC and/or ESBLs. In the test, five disc included IMP, FOX, FEP, CTX, CDOT were selected. According to the results of the bacterial susceptibility testing, AmpC and/or ESBLs was screened out elementarily. If AmpC producing strains were suscepted, OB5 inhibitory test in vitro was followed. Results In 165 cases with SBP of severe hepatopathy.simple bacteria caused no less than 90%. Gram-negative bacteria accounted for 59.2%, among which Escherichia coli (E.coli) was first. Gram-positive bacteria were 36.9% and main bacterium was Slaphycococcus aures (S.aures). Anaerobe were 1.7%. In 218 cases with secondary peritonitis .mixed infection of aerobe and anaerobe was predominant. Most of the pathogens were gram-negative,among which E.coli came first (51.1%), men Ps aeruginosa (11.8%), wliile S.aures and Enterococcus were the most frequenlly isolated gram-postive aerobes. The most common type of anaerobes was Bacteroides fragilis (B.fragilis). Morerecently .gram-negative bacteria have high resistance rate to antimicrobial. The resistance rate to the third-generation cephalosporins was up to 50%. AmpC and/or ESBLs have been documented as a prevalent mechanism of b-lactam resistance in multi-drug resistant bacteria. A K-B method was established to dectet phenotypically isolates which produced AmpC and/or ESBLs. We detected 70 isolates of Ps aeruginosa and 30 isolates of E. cloacae and used 4 standard strains producing AmpC or ESBLs as controls. It showed that, all standard strains were detected correctly. Among 70 strains of Ps aeruginosa, 40 strains were considered as hyperproduction AmpC enzyme, 18 strains were ESBLs-producing, 4 strains produced both of them. Among 30 strains of E.cloacae, 14 strains produced AmpC, 10 strains produced ESBLs, 5 strains produced both of them. The rest multi-resistant strains were neither AmpC nor ESBLs. In the meantime, this test can be developed to study induction of inducible b-lactamases (IB) of gram-negative bacteria. Conclusions The pathogenic bacteria of primary peritonitis were significally different from secondary peritionitis. The incidence of opportunistic pathogen have been increasing over the past five years. We should pay attention to gram-negative enteric bacilli,which have high resistance rate to antibiotics. Imipenem/cilastain alone or cefoperazone/sulbactam with amikacin or fluoroquinolones should be regarded as the first-line antibiotics in empirical treatment. Vancomycin with rifampicin or fosfomycin should be the optimal choice to infection of gram positive coccus. For those situations in which the gram strain is suggestive of anaerobe is evident, antibiotics with activity against anaerobic organisms should be added. As to multi-drug resistant bacteria, this test can detect the strains whether producing ESBLs . and/or the AmpC or not. Inripenem,fourth-genemation cephalosprins, amikacin or tluroquinolones can be chosed to treat producing the AmpC bacteria. ESBLs producing strains had resistant to 3 -lactamc antibiotic p -lactamasc-inhibitor combinations and cefoxitin,but few of which was resistant to...
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