Emergence of Gentamicin- and Carbenicillin-Resistant Pseudomonas aeruginosa in a Hospital Environment

Abstract

Strains of Pseudomonas aeruginosa resistant to either gentamicin or carbenicillin have been noted since their introduction into clinical use. During a 6-month period, twice-weekly cultures were obtained from all patients treated with either gentamicin or carbenicillin and from all patients with a positive culture for P. aeruginosa . Susceptibility testing to gentamicin and carbenicillin and pyocine typing were performed on all isolates. Organisms with a minimal inhibitory concentration greater than 12.5 μg of gentamicin per ml or greater than 100 μg of carbenicillin per ml were defined as resistant. P. aeruginosa was cultured from 238 patients. One patient was initially infected with a gentamicin-resistant isolate. In 11 other patients, serial cultures revealed the emergence of resistance to gentamicin. All but one of these resistant isolates occurred in patients treated with gentamicin. In eight instances the pyocine and/or serological types before and after the change in sensitivity pattern were the same. Gentamicin-resistant P. aeruginosa emerged significantly more often in patients treated with gentamicin than in those who did not receive gentamicin. Carbenicillin-resistant P. aeruginosa emerged in four of 14 patients treated with carbenicillin. Seventeen of the 238 patients were infected de novo with carbenicillin-resistant P. aeruginosa . Carbenicillin-resistant P. aeruginosa emerged significantly more often in patients treated with carbenicillin than in those who did not receive carbenicillin. No evidence was found for in-hospital spread of resistant P. aeruginosa .

beta-Lactam-resistant Pseudomonas aeruginosa with modified penicillin-binding proteins emerging during cystic fibrosis treatment

“…There is, however, another class of resistance associated with treatment failure, in which inactivating enzymes have not been implicated (4,30). For /8-lactam antibiotics, this latter resistance usually manifests itself in smaller but significant increases in minimal inhibitory concentrations (MICs) (8,15,28) and has been assumed to be due to changes within the cell envelope resulting in a reduced rate of penetration of the antibiotic (4). A penetration barrier has been suggested by Zimmerman (31) to explain the intrinsic relatively narrow spectrum of susceptibility to /1-lactams observed in P. aeruginosa.…”

In Vitro Susceptibility of Gentamicin-Resistant Enterobacteriaceae and Pseudomonas aeruginosa to Netilmicin and Selected Aminoglycoside Antibiotics

“…Resistance to gentamicin among the Enterobacteriaceae and Pseudomonas aeruginosa appears to be a problem of increasing importance (5,12). At the Wadsworth VA Hospital amikacin was shown to be the most effective aminoglycoside in vitro against gentamicin-resistant Enterobacteriaceae and P. aeruginosa (8,12).…”

Comparative in vitro activities of SCE-129, sulbenicillin, gentamicin, and dibekacin against Pseudomonas

“…In the chemotherapy of P. aeruginosa infection, sulbenicillin, carbenicillin, and several aminoglycoside antibiotics have been routinely administered. Recently, however, an increasing number of strains of P. aeruginosa resistant to those antibiotics has been reported (2,3,6,8,18). Furthermore, aminoglycoside antibiotics such as gentamicin and dibekacin often develop oto-and nephrotoxicities (1,4,7,9,10,14,20,21).…”

“…SCE-129 (CGP 7174/E) [3-(4-carbamoyl-1-pyridiniomethyl) - 7,6 -(D -a -sulfophenylacetamido) -ceph -3 -em -4 -carboxylate monosodium salt] is a new semisynthetic cephalospoin. SCE-129 has a marked in vitro antibacterial activity against clinical isolates of Pseudomonas aeruginosa, including carbenicillin-resistant strains, and in vivo SCE-129 is more active than carbenicillin (19).…”