Susceptibilities of bacterial isolates from patients with cancer to levofloxacin and other quinolones

Abstract

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...

Effectiveness of Ciprofloxacin, Levofloxacin, or Moxifloxacin for Treatment of Experimental Staphylococcus aureus Keratitis

“…Levofloxacin (a broad-spectrum fluoroquinolone) is the optically active L isomer of the racemate ofloxacin. Levofloxacin has activity against gram-negative bacteria similar to that of ciprofloxacin or ofloxacin and has a greater potency in vitro against gram-positive bacteria (8,10,24).…”

Open-label crossover study to determine pharmacokinetics and penetration of two dose regimens of levofloxacin into inflammatory fluid

“…In vitro studies suggest that it is approximately twice as active as ofloxacin (3) and, compared with ciprofloxacin, has similar or enhanced activity against gram-positive organisms (3,5,9).…”

Comparative in vitro Activity of Levofloxacin and Ciprofloxacin against Bacterial Isolates from Neutropenic Patients

“…In the present study, the activity of levofloxacin was comparable to or greater than that of ciprofloxacin on the majority of gram-negative organisms tested. Dholakia et al [16] found levofloxacin to be two to four times less active than ciprofloxacin against gram-negative bacterial isolates from cancer patients. Although quinolone resistance in a variety of species, such as staphylococci, enterococci, and Pseudomonas spp., has been recognized for some time, levels of resistance in E. coli were extremely low [16][17][18].…”

“…Dholakia et al [16] found levofloxacin to be two to four times less active than ciprofloxacin against gram-negative bacterial isolates from cancer patients. Although quinolone resistance in a variety of species, such as staphylococci, enterococci, and Pseudomonas spp., has been recognized for some time, levels of resistance in E. coli were extremely low [16][17][18]. However, recent European reports revealed that quinolone resistance of E. coli is increasing in neutropenic patients who had received fluoroquinolones as prophylaxis [19,20].…”