The inhibitory and bactericidal activities of carbenicillin, ticarcillin, moxalactam, cefoperazone, azlocillin, piperacillin, ceftazidime, and three aminoglycosides, alone and in various combinations, were determined against 60 isolates of Pseudomonas aeruginosa from the sputum of patients with cystic fibrosis. Ceftazidime was the most active ,B-lactam, with minimum inhibitory and bactericidal concentrations for 90o of isolates of 4 ,ug/ml. Moxalactam was the least active of the new -lactams, with activity equivalent to that of carbenicillin; each had a minimum inhibitory concentration for 90% of isolates of 64 ,ug/ml and a minimum bactericidal concentration for 90% of isolates of 128 p.g/ml. Of the recently introduced 3-lactam derivatives, azlocillin, cefoperazone, ceftazidime, moxalactam, and piperacillin have a higher order of activity than their predecessors against not only the Enterobacteriaceae but also against Pseudomonas aeruginosa (2,10,13,15,18). Thus, they might be useful in the treatment ofP. aeruginosa pulmonary infections which are currently difficult to manage in patients with cystic fibrosis (CF). This possibility led to the current study of the activities of these new 3-lactams, alone and in combination with each other or gentamicin, tobramycin, and amikacin, against 60 isolates of P. aeruginosa from the sputum of patients with CF. MATERIALS AND METHODSA total of 60 isolates of P. aeruginosa, including mucoid and nonmucoid strains, was identified by standard microbiological methods. The organisms were then stored on tryptic soy agar slants and were checked for purity and subcultured monthly.Moxalactam (Eli Lilly & Co.), piperacillin (Lederle Laboratories), carbenicillin (Roerig-Pfizer Co.), azlocillin (Delbay Research Corp.), ticarcillin (Beecham Laboratories), cefoperazone (Pfizer Inc.), ceftazidime (Glaxo Research Group), gentamicin (Schering Corp.), tobramycin (Eli Lilly), and amikacin (Bristol Laboratories) were furnished as dry powders. Stock solutions were prepared from these powders and were used immediately or stored at -70°C for no longer than 2 weeks.Minimum inhibitory concentrations (MICs) were determined by microbroth dilution, and combination studies were done by microbroth checkerboard methods. Mueller-Hinton broth was used for all determinations. Mueller-Hinton broth was adjusted to optimal calcium and magnesium concentrations and a pH of 7.2 to 7.4 (6). The preparation and inoculation of microbroth plates were accomplished with the MIC-2000 system (Dynatech Corp.). Plates were used immediately or stored at -70°C for no longer than 2 weeks. Microbroth plates received an inoculum consisting of a 10' dilution of a log-phase culture adjusted to the density of a 0.

We tested CI-919 (AT-2266), a nalidixic acid analog, against 555 gram-positive and gram-negative bacteria, using microbroth or agar dilution methods. Current therapy of Pseudomonas aeruginosa infections requires parenteral administration of aminoglycosides, semisynthetic peniciliins, or one of the newer broad-spectrum cephalosporins. The development of a drug that is effective after oral administration would represent a major therapeutic advance.CI-919 (AT-2266; 1-ethyl-6-fluoro-1,4-dihydro -4 -oxo -7 -(1 -piperazinyl) -1,8 -naphthyridine-3-carboxylic acid) is a new antimicrobial agent structurally related to nalidixic acid and pipemidic acid (Fig. 1). Preliminary reports have indicated that CI-919 is active against both grampositive and gram-negative bacteria, including P. aeruginosa and aminoglycoside-resistant organisms (4,5,8). We previously showed that CI-919 was more active than tobramycin against systemic P. aeruginosa infections in mice

Del.) is a commercially available blood culture system for use in pediatrics. The methodology is based on blood lysis followed by direct plating of the sample on culture media to detect bacteria and fungi. Comparative recovery rates of pathogens from blood collected in this and a conventional broth system were similar. The Isolator detected 104 of 120 clinically signfficant isolates, whereas 106 of 120 isolates were detected by the broth system. The major advantage of the Isolator methodology was early detection of septicemia. Initial detection of gram-negative bacteria occurred an average of 14.2 h earlier by the Isolator system than by the conventional broth method. The Isolator also permitted quantitation of bacteremia and fungemia. Probable contaminants were recovered from 10.0% of the cultures processed by the Isolator, but steps which could be taken to minimize this problem were identified. The Isolator is a useful method for pediatric blood cultures.

The antibacterial activity of BMY-28100, a new oral cephalosporin, was measured against 300 bacterial isolates from pediatric infections by standard agar dilution methodology. The effect of inoculum size on activity was also assessed. BMY-28100 was more active than cephalexin or cefaclor against all bacterial species tested.BMY-28100 {5-thia-1-azabicyclo[4.2.0] oct-2-ene-2 carboxylic acid-7- [[amino(4-hydroxyphenyl)new oral cephalosporin which has shown activity against major pediatric pathogens, both in vitro and in experimental infections

In vitro susceptibility to 17 antimicrobial agents was determined for Aeromonas caviae, A. hydrophila, and A. sobria isolated from feces of patients with diarrhea. The three Aeromonas species shared a similar susceptibility pattern, except to cephalothin. Of the oral antimicrobial agents, the quinolones, followed by chloramphenicol, were most active; trimethoprim-sulfamethoxazole and tetracycline had good but variable activity.