[The impact of antibiotic use on hospital-acquired pneumonia: data of etiology tests]

Abstract

Aim of the study: To investigate most common pathogens isolated from the hospital-acquired pneumonia patients bronchoalveolar lavage fluid in Kaunas University of Medicine Hospital according to the previous antibiotic use and to estimate pathogens antibacterial susceptibility.

Materials and methods: Results of 87 hospital-acquired pneumonia patients bronchoalveolar lavage fluid quantitative cultures were analyzed. Microorganisms isolated in clinically significant amount were considered as the etiological agents and included into analysis. Susceptibility was tested using the standard methods. Previously untreated patients were considered if the antibacterials were not administered at all or were used less than for 24 hours.

Results: H. influenzae isolation in significant amount rates were higher in previously untreated patients group comparing to previously treated (29.2%. (n=14) and 5.1% (n=2), respectively, p<0.05). Non-fermenters (P. aeruginosa and Acinetobacter spp.) isolation rates were higher in those previously treated comparing to untreated patients - (31.0% (n=13) and 4.2% (n=2), respectively, p<0.05). All H. influenzae strains were susceptible to ampicillin and cefuroxime. 22.2-44.4% of P. aeruginosa strains were resistant to ceftazidime, amikacin and ciprofloxacin. Estimated Acinetobacter spp. resistance to ciprofloxacin and gentamycin was 83.3% and to ampicillin/sulbactam - 16.7%. All methicillin-susceptible S.aureus were also susceptible to gentamycin and fucidin and methicillin resistant to rifampicin and vancomycin.

Conclusions: Previous antibiotic treatment has an impact on pneumonia etiology testing. H. influenzae strains are more common isolated hospital-acquired pneumonia etiologic agents in previously untreated patients. The low antibacterial resistance was found enabling the use of aminopenicillins for treatment if H. influenzae infection suggested. The use of antibacterials increases non-fermenters isolation rates and combined antipseudomonal treatment is reasonable in these patients.