Susceptibility of Pseudomonas aeruginosa to fluoroquinolones following four years of use in a tertiary care hospital

Changes in antibiotic resistance of the most common Gram-negative bacteria isolated in intensive care units

We studied the changes in antibiotic resistance of the most common Gram-negative bacteria isolated in the intensive care units at our hospital in 2000 and 2002. Bacterial identification was performed by use of the VITEK 60 analyser, and antibiotic susceptibilities were tested by the VITEK 60 analyser and the disk diffusion agar method. The bacteria isolated most frequently were Pseudomonas aeruginosa (132 strains in 2000 and 106 in 2002), Acinetobacter calcoaceticus (98 and 109 strains, respectively) and Klebsiella pneumoniae (53 and 83 strains, respectively). Acinetobacters presented the highest percentage resistance, with significant increases in resistance to imipenem (15% in 2000 and 67% in 2002) and piperacillin/tazobactam (41% and 72%, respectively). P. aeruginosa presented a significant increase in resistance to all antibiotics, except ceftazidime. A large increase was observed in the resistance of K. pneumoniae to amikacin (from 10% to 50%), ceftazidime (from 80% to 90%) and tobramycin (from 80% to 90%). No imipenem-resistant strains of K. pneumoniae were found.

[The good use of antibiotics in intensive care: results of a program for rationalization of prescriptions]

OBJECTIVE

To assess the impact of an antibiotic prescribing programme in a intensive therapy unit.

TYPE OF STUDY

Prospective comparative study.

METHODS

We compared antibiotic prescriptions and bacterial susceptibility to antimicrobial agents before and after introduction of a programme focusing on injection control and therapeutic indications.

RESULTS

The introduction of the programme resulted in a major decrease in antibiotic administration. Moreover, the susceptibility of Pseudomonas aeruginosa to ticarcillin increased from 40 to 68%, and susceptibility of Staphylococcus aureus to methicillin increased from 55 to 73%.

CONCLUSIONS

Antibiotic control policies must be considered integral to any effort to decrease resistance and cost of therapy with antibiotics.

Antimicrobial resistance in bacterial chronic sinusitis

Recent reports describe the emergence of antimicrobial resistant bacteria in acute sinusitis and an increased incidence of enteric gram negative bacilli in chronic sinusitis. The objective of this cross sectional study is to identify the emergent resistance patterns in bacterial chronic sinusitis. Specifically, this article seeks to characterize the bacteriology of outpatient chronic sinusitis, then to compare the antimicrobial susceptibilities of the bacterial isolates with standard culture data from a tertiary care center. Between March and August, 1994, 113 new outpatients presented with chronic sinusitis at a major teaching institution. Of these patients 34 underwent endoscopically guided aerobic culture of the paranasal sinuses and nasal cavities. Of the 48 total cultures, there were 43 positive cultures yielding 72 isolates. Thirty-eight cultures had two or fewer isolates; four cultures had three plus isolates, and one culture grew out normal flora. The most frequently isolated organisms were coagulase negative Staphylococcus (SCN), 20 (28%); Pseudomonas aeruginosa, 12 (17%); and Staphylococcus aureus, 9 (13%). Within the limited sample size for each isolate, Staphylococcus coagulase negative, Pseudomonas, and Pneumococcus demonstrated higher antimicrobial resistance compared to the medical center's corresponding nonurinary isolates. Additionally, three of six patients with Pseudomonal aeruginosa (50%) had a quinolone resistant strain. These preliminary data suggest that both an increased incidence of antimicrobial resistance and of enteric gram negative bacilli may exist in these outpatient, tertiary care center patients with chronic bacterial sinusitis.

Susceptibility of microorganisms isolated from chronic suppurative otitis media to ciprofloxacin

In order to evaluate the susceptibility of the microorganisms isolated from chronic suppurative otitis media to ciprofloxacin, cultures of specimens from 127 patients with chronic suppurative otitis media and their antibiotic sensitivity results were examined. The most common aerobic isolates were Pseudomonas sp., Proteus sp., and Staphylococcus aureus with recovery rates of 40.7%, 21.6% and 19.1% respectively. Sensitivity results showed that 6.2% of Pseudomonas isolates, 2.9% of Proteus isolates, 10% of Staphylococcus aureus isolates and 8.3% of Escherichia coli isolates were resistant to ciprofloxacin.

Quinolone resistance in Pseudomonas aeruginosa and Staphylococcus aureus. Development during therapy and clinical significance

This review focuses on published information on the experimental as well as clinical data on the emergence of quinolone resistant isolates. In the course of clinical use of fluoroquinolones, only a sporadic emergence of quinolone resistance has been noted. The resistant organisms emerged particularly in certain clinical settings where large numbers of organisms frequently causing chronic infections are present and/or in loci where quinolone concentrations may not be optimal. In terms of occurrence in individuals, quinolone resistance has emerged most frequently in hospitalized and nursing-home patients with identifiable risk factors. Epidemiological studies revealed that in nearly all the cases studied one or one predominating quinolone resistant clone was selected that was horizontally transmitted. Thus, the emergence of quinolone resistance is not due to an independent selection of resistant strains in a number of patients, but to the clonal spread of one strain once it has acquired quinolone resistance. Therefore, the rate of quinolone resistance is very likely to be lower than reported.