急性単純性膀胱炎患者からのβ-lactamase産生菌の分離頻度

Abstract

女子の急性単純性膀胱炎患者113例由来の尿中分離菌122株のβ-lactamase活性を測定し, E. coli 105株中18株(17.1%)およびE. cloacae 1株中1株が陽性, またS epidermidis 12株, E. faecalis 3株およびS. aureus 1株のグラム陽性球菌はすべて陰性と判定された.薬剤感受性試験の成績との関係では, β-lactamase産生株中のABPC, CBPCおよびCET耐性株の占める割合は非産生株に比し有意に高い結果が得られた.以上の成績より, 単純性UTIにおいても, 高率とはいえないがβ-lactam剤, ことにpenicillin系抗生剤に対する耐性株がみられ, その耐性機構にβ-lactamaseが重要な役割を果していることが考えられた

A total of 122 bacterial strains isolated from urine specimens of 113 female patients with acute uncomplicated cystitis were used for the study of beta-lactamase production and their susceptibility to various antimicrobial agents was determined. Beta-Lactamase activity was qualitatively determined by a paper strip acidimetric method with benzylpenicillin as substrate and by chromogenic cephalosporin methods using pyridine-2-azo-p-dimethylaniline cephalosporin or nitrocefin as substrate. Susceptibility to antimicrobial agents, including ampicillin, carbenicillin, cephalexin, cephalothin, gentamicin, minocycline, fosfomycin, pipemidic acid and sulfamethoxazole-trimethoprim was examined by a disc method. The beta-lactamase-producing strains detected by at least one of the three tests were found in 18 of 105 Escherichia coli isolates and in the single strain of Enterobacter cloacae dermidis, 3 Enterococcus faecalis and 1 Staphylococcus aureus produced beta-lactamase. The isolation rate of strains resistant to ampicillin, carbenicillin and cephalothin in the beta-lactamase-producing strains was significantly higher than that in the non-beta-lactamase-producing strains (p less than 0.01). These results suggest that beta-lactamase plays an important role in developing resistance to beta-lactam antibiotics in patients with uncomplicated urinary tract infection as well as complicated infection.