Pseudomonas aeruginosa bacteremia: associations with a source of infection and antibiotic resistance

Aim of the study. To determine the associations between the source of infection and antibiotic resistance in patients with Pseudomonas aeruginosa bacteremia. Material and methods. A retrospective analysis of 50 patients with Pseudomonas aeruginosa bacteremia was carried out. If sepsis was suspected, blood culture was incubated in an automatic system BACTEC 9240. Then bacteria were identified, and their antibiotic resistance was estimated by disc diffusion method. If Pseudomonas aeruginosa strains were resistant to three or more antibiotics, they were considered as multidrug-resistant. Results. The origin of bacteremia was confirmed in 33 (66%) patients. Lower respiratory tract was the predominant source of Pseudomonas aeruginosa bacteremia (81.8%, n=27) as compared with infection of wound (39.4%, n=13), urinary tract (15.2%, n=5), and drain or cerebrospinal fluid (9.1%, n=3) (P<0.05). Eighteen percent (n=9) of strains, which caused bacteremia, were resistant to ceftazidime; 38% (n=19), to piperacillin; 22% (n=11), to imipenem; 26% (n=13), to meropenem; 24% (n=12), to ciprofloxacin; 40% (n=20), to gentamicin; and only 8% (n=4), to amikacin. Multidrug-resistant Pseudomonas aeruginosa strains were more frequently isolated if a source of infection was wound comparing to a source of other localization (61.5%, n=8 and 20.0%, n=4, respectively; P<0.05). Resistance of Pseudomonas aeruginosa strains to imipenem was associated with resistance to ciprofloxacin (13.2%, n=5 and 50.0%, n=6, retrospectively; P<0.05), but resistance to meropenem - both to ciprofloxacin and amikacin. Conclusions. The predominant source of Pseudomonas aeruginosa bacteremia was lower respiratory tract, and multidrug-resistant strains caused bacteremia more frequently if a source infection was wound. Pseudomonas aeruginosa resistance to carbapenems was associated with resistance to ciprofloxacin and resistance to meropenem-also to amikacin. Resistance of strains to ceftazidime and piperacillin was associated with resistance to gentamicin.