Evaluation of Current Activities of Fluoroquinolones against Gram-Negative Bacilli Using Centralized In Vitro Testing and Electronic Surveillance

Abstract

Given the propensity for Enterobacteriaceae and clinically significant nonfermentative gram-negative bacilli to acquire antimicrobial resistance, consistent surveillance of the activities of agents commonly prescribed to treat infections arising from these organisms is imperative. This study determined the activities of two fluoroquinolones, levofloxacin and ciprofloxacin, and seven comparative agents against recent clinical isolates of Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia using two surveillance strategies: 1) centralized in vitro susceptibility testing of isolates collected from 27 hospital laboratories across the United States and 2) analysis of data from The Surveillance Network Database-USA, an electronic surveillance network comprising more than 200 laboratories nationwide. Regardless of the surveillance method, Enterobacteriaceae, P. aeruginosa, and A. baumannii demonstrated similar rates of susceptibility to levofloxacin and ciprofloxacin. Susceptibilities to the fluoroquinolones approached or exceeded 90% for all Enterobacteriaceae except Providencia spp. (<65%). Approximately 70% of P. aeruginosa and 50% of A. baumanii isolates were susceptible to both fluoroquinolones. Among S. maltophilia isolates, 50% more isolates were susceptible to levofloxacin than to ciprofloxacin. Overall, the rate of ceftazidime nonsusceptibility among Enterobacteriaceae was 8.7%, with fluoroquinolone resistance rates notably higher among ceftazidime-nonsusceptible isolates than ceftazidime-susceptible ones. Multidrug-resistant isolates were present among all species tested but were most prevalent for Klebsiella pneumoniae and Enterobacter cloacae. No gram-negative isolates resistant only to a fluoroquinolone were encountered, regardless of species. Thus, while levofloxacin and ciprofloxacin have maintained potent activity against Enterobacteriaceae, the potential for fluoroquinolone resistance, the apparent association between fluoroquinolone and cephalosporin resistance, and the presence of multidrug resistance in every species examined emphasize the need to maintain active surveillance of resistance patterns among gram-negative bacilli.The potent activity of fluoroquinolones (FQs) against a myriad of gram-negative and gram-positive bacterial pathogens has fostered a decade of frequent and continued clinical use. Recently, levofloxacin has broadened the range of indications for FQs to include community-acquired respiratory tract infections attributable to penicillin-resistant Streptococcus pneumoniae. In spite of their success, concern remains regarding the development and increasing prevalence of resistance to FQs among human pathogens and colonizing bacterial species (12,23,24,25).A decline in the activity of FQs would be especially problematic in view of the ability of gram-negative bacilli to acquire resistance to all other classes of antimicrobials (4,5,10,11,14,15,17,20,22,29,30). This ability underscores the need to closely monitor FQ activity in the Uni...

High prevalence of plasmid-mediated quinolone resistance determinants in Enterobacter cloacae isolated from hospitals of the Qazvin, Alborz, and Tehran provinces, Iran

“…Quinolones are among the most commonly prescribed antimicrobials for the treatment of serious infections caused by E. cloacae and other members of the Enterobacteriaceae family. However, the development of resistance to these antibiotics in the causative bacteria has complicated treatment and may lead to treatment failures (30) . In recent years, PMQR has been reported in several studies, especially in enterobacteria (8) .…”

Antibiotic Sensitivity Pattern of Uropathogens at Khwaja Yunus Ali Medical College Hospital

“…The widespread use, more often the misuse, of antimicrobial drugs has led to a general rise in the emergence of resistant bacteria. It is reported that in the United State there is rise in the resistan t strains to ampicilli n due to its widesprea d use 14 . With this evidence from our study, we can suggest meropenem, amikacin, ceftazidime, gentamicin and imipenem to be prescribed as the empirical treatment for UTI.…”

Factors Associated with Relative Rates of Antibiotic Resistance in Pseudomonas aeruginosa Isolates Tested in Clinical Laboratories in the United States from 1999 to 2002

“…There have been a number of centralized in vitro studies conducted in the United States from 1997 to 2002 that have studied the susceptibility of P. aeruginosa (4,6,7,13,17). For the fluoroquinolones, it appears that susceptibility among P. aeruginosa isolates is decreasing in the United States (2,4,6,7,13,14,16), perhaps because of increasing or cumulative fluoroquinolone use, the lack of adherence to approved infection control prac- MDR (resistance to three or more antimicrobial agents) accounted for 24.9% of all isolates in this study. MDR was significantly higher for nursing home patients (29.9%) and ICU patients (29.5%) than for non-ICU patients and outpatients (P Ͻ 0.05).…”

“…Although several surveillance studies have reported on the relative in vitro activities of various antimicrobial agents (4,6,7,13,16), an extensive comparative statistical analysis of resistance to antimicrobial agents relative to factors associated with resistance has not been performed. Such analysis is important to more completely elucidate the status of antimicrobial resistance among P. aeruginosa isolates and to attempt to understand and predict the direction and chronology of future resistance trends.…”