thienamycin and Pseudomonas-Infections

Topics: Anti-Bacterial Agents; beta-Lactamases; beta-Lactams; Cefoperazone; Cefotaxime; Cefsulodin; Ceftazidime; Ceftriaxone; Cephalosporins; Cephamycins; Drug Stability; Lactams; Moxalactam; Penicillins; Pseudomonas aeruginosa; Pseudomonas Infections; Thienamycins

It is generally assumed that the antibiotic prescription policy of a hospital has a significant impact on bacterial resistance rates; however, few studies are available to support this concept with valid statistical data. During a 3-year period from 1997 to 2000, we monitored the consumption of beta-lactam and other antibiotics with known activity against Pseudomonas aeruginosa in a 600-bed community hospital. Monthly isolations of P. aeruginosa were assessed, and resistance rates were recorded. Partial correlation coefficients between consumption and resistance rates were determined, taking into account possible associations with other variables such as seasonal effects and transfers from other hospitals. A total of 30 +/- 7 novel P. aeruginosa strains per month were isolated without epidemic clustering. Prescriptions of imipenem varied significantly during the study period, while prescriptions of other antipseudomonal agents were stable, with the exception of an increase in piperacillin-tazobactam prescriptions. Rates of resistance of P. aeruginosa to the antimicrobial agents used showed a time course similar to figures for imipenem consumption. Monthly rates of resistance to imipenem (partial correlation coefficient [cc], 0.63), piperacillin-tazobactam (cc, 0.57), and ceftazidime (cc, 0.56) were significantly associated with imipenem prescription rates in the same or the preceding month, while consumption of ceftazidime or piperacillin-tazobactam had no apparent association with resistance. Among the variables investigated, imipenem consumption was identified as the major factor associated with both carbapenem and beta-lactam resistance in endemic P. aeruginosa. Periods of extensive imipenem use were associated with significant increases in resistance. Our data support the concept that a written antibiotic policy which balances the use of various antibiotic classes may help to avoid disturbances of a hospital's microbial sensitivity patterns.

Topics: beta-Lactam Resistance; Drug Prescriptions; Drug Utilization; Hospitals, Community; Humans; Hygiene; Imipenem; Pseudomonas aeruginosa; Pseudomonas Infections; Public Policy; Seasons; Thienamycins

Susceptibility tests by disk diffusion and by E-test and molecular typing by macrorestriction analysis were performed to determine the relatedness of Pseudomonas aeruginosa isolates from three distinct hospitals. The resistance profile of 124 isolates to 8 antimicrobial agents was determined in three different hospitals, in Porto Alegre, Brazil. Frequencies of susceptibility ranged from 43.9% for carbenicillin to 87.7% for ceftazidime. Cross-resistance data of imipenem-resistant isolates indicated that most (70%) were also resistant to carbenicillin, although 30% remained susceptible to ceftazidime and cefepime. In general, susceptibility profiles were not able to determine relatedness among isolates of P. aeruginosa. On the other hand, molecular typing by macrorestriction analysis demonstrated high discriminatory power and identified 66 strains among 72 isolates of P. aeruginosa. Imipenem-susceptible isolates were all different. However, identical clones of imipenem-resistant isolates were found in two of the hospitals, despite variable response to other antibiotics. No clustering of infection among the different medical centers was observed. In conclusion, clones of P. aeruginosa did not spread among the different hospitals in our city even though related isolates of imipenem-resistant P. aeruginosa were found.

Topics: Bacterial Typing Techniques; Brazil; Cross Infection; Drug Resistance, Multiple, Bacterial; Electrophoresis, Gel, Pulsed-Field; Genotype; Hospitals; Humans; Imipenem; Microbial Sensitivity Tests; Pseudomonas aeruginosa; Pseudomonas Infections; Respiratory Tract Diseases; Restriction Mapping; Thienamycins