Biomedical subjects
Publications and source records attributed to B LeBlanc.
Teichomycin A2 was evaluated in vitro against clinical isolates, and its activity was compared with that of other antibiotics. This compound was very active against all organisms tested; its activity was comparable to that of vancomycin, and it was superior to several other antibiotics when tested against gram-positive cocci. Because of its in vitro activity, it deserves clinical evaluation.
The in vitro susceptibilities of 98 isolates of JK diphtheroids to teichomycin, vancomycin, and eight other antibiotics was investigated. Teichomycin and vancomycin were extremely active against all the isolates tested. The 90% minimal inhibitory concentrations for teichomycin and vancomycin were 1.56 and 0.78 micrograms/ml, respectively. The majority of the isolates were resistant to ticarcillin, methicillin, erythromycin, tetracycline, chloramphenicol, clindamycin, and cephalothin.
The in vitro activities of new beta-lactam antibiotics was studied and compared with those of other known agents against 51 clinical isolates of Acinetobacter calcoaceticus subsp. anitratus and 23 isolates of A. calcoaceticus subsp. lwoffi. Of the new beta-lactam antibiotics, imipemide (N-formimidoyl thienamycin), ceftazidime, ceftizoxime, ceftriaxone, and piperacillin demonstrated good activities. The minimal inhibitory concentrations for A. calcoaceticus subsp. lwoffi were lower than those obtained for A. calcoaceticus subsp. anitratus.
The in vitro activity of thienamycin was compared to that of other antibiotics against a large panel of bacteria obtained in blood cultures from cancer patients. This compound was the most active against gram-positive cocci and also proved to be extremely active against the gram-negative bacteria. It was also very active against multi-resistant gram-negative bacilli. Because of its broad spectrum of activity including Pseudomonas spp., thienamycin deserves clinical testing in the future.
Netilmicin, a semisynthetic derivative of sisomicin, was tested in vitro against 600 clinical bacterial isolates. At a concentration of 1.56 mug/ml, over 90% of gram-negative bacilli were inhibited. Netilmicin was substantially more active against isolates of Serratia marcescens and Enterobacter spp. than gentamicin, sisomicin, tobramycin, or amikacin. Isolates of Staphylococcus aureus (both penicillin G susceptible and resistant) were quite susceptible to netilmicin. Most isolates of Klebsiella spp. and Serratia spp. and some of the isolates of Pseudomonas aeruginosa that were resistant to gentamicin proved to be susceptible to netilmicin.
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We conducted a survey of susceptibility among 758 gram-negative bacilli (GNB; collected from cancer patients over a 3-month period) to commonly used antibiotics. The overall resistance among GNB was least for piperacillin/tazobactam and meropenem (5 and 6%, respectively) followed by cefepime (8%), imipenem (9%), amikacin (12%), ofloxacin (13%), ciprofloxacin, ceftazidime and ticarcillin/clavulanate (14% each), aztreonam (18%) and tobramycin (24%). In comparison to data on antibiotic resistance to ceftazidime, imipenem, ciprofloxacin and aztreonam in similar studies in 1985 and 1994, resistance has significantly increased to all four antibiotic classes. Based on our current study, meropenem, cefepime, imipenem and piperacillin/tazobactam would be the most appropriate choices in our institution for empiric therapy of GNB infections in febrile neutropenic patients.
A survey of the susceptibility of gram-negative bacilli isolated from cancer patients to broad-spectrum antimicrobial agents was conducted. The organisms were isolated from all patient specimens submitted to the microbiology laboratory during a 3-month study period. Overall, the least resistance was observed against cefoperazone/sulbactam, ciprofloxacin, and imipenem. Of these, cefoperazone/sulbactam has had limited usage at our institution. Drugs used more frequently (piperacillin, aztreonam, cefoperazone, ceftazidime) were associated with greater levels of resistance. Imipenem and ciprofloxacin have enjoyed wide usage but the level of resistance remains low.