No abstract

Community Gram-negative urinary tract isolates remain highly sensitive to mecillinam and ciprofloxacin, but a significant number have developed resistance to trimethoprim/sulfamethoxazole. Further studies are required to determine the clinical significance of these results.

This investigation used the postantibiotic effect (PAE) and killing curves to provide data on the antimicrobial activity of subinhibitory (1/8×, 1/4× and 1/2× minimum inhibitory concentration; MIC) and inhibitory (1 × MIC) concentrations of amikacin, gentamicin and tobramycin against Pseudomonas aeruginosa. Subinhibitory concentrations (l/4× and 1/2× MIC) of aminoglycosides demonstrated a reproducible PAE. At 1/4 × MIC, the order of duration of the PAE was approximately 15 min for all aminoglycosides, while at 1/2 × MIC all three aminoglycosides displayed a similar PAE of approximately 40 min. Killing-curve studies demonstrated that subinhibitory concentrations of aminoglycosides either decrease bacterial growth for several hours (1/4× and 1/2 × MIC) or produce stasis of growth for several hours (1/8 × MIC). Only inhibitory aminoglycoside concentrations (1 × MIC) proved to be bactericidal. Subinhibitory concentrations of aminoglycosides decrease bacterial growth and produce a PAE against P. aeruginosa.

180 respiratory tract isolates of Streptococcus pneumoniae were collected from 18 medical centers in 9 of the 10 Canadian provinces. Penicillin-intermediate and -resistant isolates occurred at rates of 14.8 and 6.4%, respectively, and these rates varied considerably by geographic region. Trimethoprim-sulfamethoxazole, tetracycline, and macrolide rates of nonsusceptibility were 12.2, 10.6, and 8.0 to 9.3%, respectively. The most potent agents studied were newer fluoroquinolones.

Infect Dis 1 994; 5(3):130-132. Episodes of bacteremia identified in a long term care facility over a seven and a half-year period from July 1984 lo December 1991 were reviewed. 1\venly-nine episodes of bacteremia were identified. a rate of 4.35/100.000 patient-days. The most common infecting organisms were Escherichia coli (11 episodes) . Streptococcus pneumoniae (four). Proteus mirabilis (lhree). Staphy lococcus aureus (lhree) and Bacteroides species (two). The source of bacteremia was urimuy in 45o/o of patients. gastrointestinal in 17o/o, pneumonia in 14o/o, skin in 14o/o and unknown in 1 Oo/o. The overall case fa tali ly rate was 24o/o. bu l for lhe final six years of the review lhe case fatality rate was only 9 .5o/o. These observations report a rate of bacteremia 10-fold lower lhan reported from olher Norlh American long term care facilities and. potentially. a lower case fatality rate. The primary site of bacteremia. however. in long term care faci lities is U1e w·inary tract. R ESIDENTS OF LONG TERM CARE FACILITIES ARE ATincreased risk for infection because of associated comorbidities, interventions n ecessitated by chronic functional problems and, possib ly, because of institutionalization. Bacteremia is an important infection because it is generally associated with a high mortality. There is limited information available, however, that describes bacteremia occurring in long term care facilities. Studies reporting bacteremia in long term care facilities in the United States have identified urinary t ract infection as the most frequent source, and reported an incidence of about 0.3/1000 patient-days (1-3). The overall mortality has been 21 to 35%. The present study of bacteremia occurring in one long term care facility in Winnipeg, Manitoba over a seven and a half-year period was undertaken to exan1ine characteristics of bacteremia in the study population and to compare this experience with that reported from other facilities in North America. PATIENT AND METHODS Institution:The Deer Lodge Centre is a long term care facility that was formerly a Veteran's Hospital. Most residents are male, with a male: female ratio of approximately 3.5: 1. During the period of this review, from July 1984 to December 1991, the centre varied in size from 199 to 420 beds. The remain ing acute care beds in the facility were progressively eliminated during this period and replaced by beds for assessment and rehabilitation. short term respite admissions and further long term care beds. This review describes bacteremia in permanent resid ents in the long term care facility beds at this institution. Residents who became acutely ill were transferred to the acute care ward in the facility where parenteral therapy and more intensive nursing care could be provided. They were not transferred to an acute care facility unless specialized intervention such as surgery was required . 'Death not directly attributed to infection be due to infection if the resident was clinically not anticipated to die within the short term and no cause ...

From 1997 to 1999, 94 study centers in 15 European, 3 North American, and 2 South American countries contributed 2,632 isolates of Streptococcus pneumoniae to an international antimicrobial susceptibility testing study. Only 62.0% of isolates were susceptible to penicillin, while 22.3% were penicillin intermediate and 15.6% were penicillin resistant. Resistance to trimethoprim-sulfamethoxazole (24.4%), azithromycin (26.0%), and clarithromycin (27.1%) was also highly prevalent. For the penicillin-resistant isolates (n ‫؍‬ 411), the MICs at which 90% of isolates are inhibited (MIC 90 s) for gemifloxacin, levofloxacin, ofloxacin, clarithromycin, and azithromycin were 0.03, 1, 2, >16, and >64 g/ml, respectively. Similarly, for isolates resistant to both azithromycin and clarithromycin (n ‫؍‬ 649), gemifloxacin, levofloxacin, ofloxacin, and penicillin MIC 90 s were 0.03, 1, 2, and 4 g/ml, respectively. Overall rates of resistance to trovafloxacin (0.3%), levofloxacin (0.3%), grepafloxacin (0.6%), and ofloxacin (0.7%) were low. For ofloxacin-intermediate and -resistant isolates (n ‫؍‬ 142), gemifloxacin had the lowest MIC 90 (0.12 g/ml) compared to the MIC 90 s of trovafloxacin (0.5 g/ml), grepafloxacin (1 g/ml), and levofloxacin (2 g/ml). For all S. pneumoniae isolates tested, gemifloxacin MICs were <0.5 g/ml, suggesting that gemifloxacin has the potential to be used as a treatment for pneumococcal infections, including those arising from isolates resistant to ␤-lactams and macrolides.

No abstract

Levofloxacin, the S-(-)-isomer of ofloxacin, was compared to ofloxacin and ciprofloxacin against > 6000 recent clinical isolates of Gram-positive and Gram-negative bacteria from six different countries. This international multicenter study demonstrated a high level of antibacterial activity of levofloxacin against all the members of Enterobacteriaceae [minimum inhibitory concentration (MIC)50s, < or = 0.03 to 0.12 mg/L] except Providencia rettgeri (MIC50, 2 mg/L), and Providencia stuartii (MIC50, 1 mg/L). Oxacillin-susceptible staphylococci (MIC50s, 0.12 to 0.25 mg/L), enterococci (MIC50s, 0.5 to 2 mg/L), and streptococci (MIC50s, 0.5 mg/L) were also susceptible to levofloxacin, but most isolates of oxacillin-resistant staphylococci had MICs of > or = 4 mg/L. Levofloxacin was also active against non-enteric Gram-negative bacilli, including Acinetobacter species (MIC50s, < or = 0.03 to 1 mg/L), Pseudomonas species (MIC50s, 0.5 to 1 mg/L) and Xanthomonas maltophilia (MIC50, 0.5 mg/L). Overall, levofloxacin inhibited 50% and 90% of all the tested strains at the concentrations of 0.12 and 4 mg/L, respectively. The activity of levofloxacin was generally two-fold greater than ofloxacin and equal to or slightly less potent than ciprofloxacin.