No abstract

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.

Abstract. This paper provides the derivation of the hitting time density of an Ornstein-Uhlenbeck process to a flat boundary. The derivation relies on a change of measure approach and delivers an explicit formula. This formula is an amended expression of the result given in Leblanc and Scaillet (1998). It corresponds to the formula given by a time substitution approach when the boundary level coincides with the mean of the invariant measure. It can for example be used to price digital up-and-in credit spread options when the logarithm of the credit spread is assumed to follow an Ornstein-Uhlenbeck process.

The antibacterial activity of levofloxacin was compared with those of ofloxacin and ciprofloxacin against bacterial isolates from patients with cancer. In general, levofloxacin was as active or was twofold more active than ofloxacin and was two-to fourfold less active than ciprofloxacin against most gram-negative pathogens. Against Pseudomonas aeruginosa, ciprofloxacin was the most active agent tested (MIC for 90% of isolates tested, 1.0 jig/ml). Overall, all three agents had similar activities against gram-positive organisms and were moderately active against methicillin-susceptible Staphylococcus aureus and coagulase-negative staphylococci, Streptococcus species, and Enterococcus species.During the past decade a large number of newer quinolones have been developed. Most of these agents, including norfloxacin, ciprofloxacin, ofloxacin, lomefloxacin, and fleroxacin, have broader antimicrobial spectra and improved bioavailabilities in comparison with those of naladixic acid (16). Some have been used for infection prevention and for the treatment of established infections in neutropenic cancer patients (2, 6, 10, 15). More recently, broad-spectrum quinolones such as ciprofloxacin, which are available for parenteral and oral administration, have made it possible to shorten the duration of antibiotic administration to febrile cancer patients in the hospital by facilitating the early discharge of such patients on oral antibiotic therapy (3). Certain low-risk neutropenic patients have even been treated as outpatients during the entire febrile episode (12). These newer applications have widened the scope of the quinolones as antibacterial agents. However, the widespread prophylactic and therapeutic usage of quinolones in neutropenic cancer patients has raised concern about the emergence of resistance to them and a reduction in their overall impact as clinically useful antibiotics.Ofloxacin exists as two optically active isomers because of the asymmetric center at C-3 of the oxazine ring, and levofloxacin (l-ofloxacin) is the more active isomer (4,5,14 796-8578. Anderson Cancer Center at Houston during the past 5 years. The majority (>90%) of these isolates were from blood culture specimens, and the rest were from various clinical sources including sputum, wounds, urine, bile, and cerebrospinal fluid. Many isolates came from patients who had received cephalosporins, penicillins, carbapenems, monobactams, and quinolones for therapy or prophylaxis. Only one isolate per patient was used for testing in order to avoid duplication. Staphylococcus aureus and Staphylococcus epidermidis isolates were considered penicillin G susceptible on the basis of an MIC of <0.1 ,ug/ml, methicillin susceptible on the basis of an MIC of s4.0 ,ug/ml, and methicillin resistant on the basis of an MIC of .8.0 ,tg/ml.Susceptibility testing was performed in accordance -with the guidelines established by the National Committee for Clinical Laboratory Standards by using a previously described microtiter broth dilution method (8,11). Briefly, orga...

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.