Background: Researching carbapenem-resistant isolates and the use of antibiotics and following infection control policies enable the identification of carbapenemase-producing bacteria and prevent their spread.
Methods: P. aeruginosa isolates were recovered from Medicine Faculty of Recep Tayyip Erdoğan University between April 2015 and October 2016 and identified by conventional methods and the automated Vitek 2 Compact (BioMerieux, France) system. Antimicrobial susceptibility experiments were performed in accordance with CLSI criteria and the automated Vitek 2 Compact system. The PCR method was investigated for the presence of β-lactamase resistance genes. PFGE typing was performed to show clonal relation among samples.
Results: Seventy P. aeruginosa strains were isolated from seventy patients. The median age of 70 cases was found 66 with minimum 17 and maximum 92 years old. 67.1% of the patients had contact with the health service in the last 90 days and 75.7% of the patients had received antimicrobial therapy in the previous 90 days. The most common comorbidity was cardiovascular diseases. Twenty-four (34.3%) strains were carbapenem resistant, 2 strains were multidrug-resistant except colistin, and none of the samples had colistin resistance. The gene encoding β-lactamase or metallo-β-lactamase was found in a total of 36 strains. The bla VEB gene was identified in only 1 strain alone, but in combination with other resistance genes in a total of 17 strains. While the bla PER gene was detected in 5 samples alone, it was found in 13 samples in combination with other genes. Among the genes encoding metallo-β-lactamase, the most bla NDM positive was detected (n=22), followed by 14 positive samples of bla KPC . bla IMP and bla VIM were detected in 5 and 1 samples, respectively. Also, the association of bla VEB - bla PER and bla VEB - bla KPC - bla NDM was found to be very high. Much more resistance genes and associations were detected in hospital-acquired samples than community-acquired samples, both proportionally and in terms of co-occurrence. Most of the community-associated strains were collected in the F2 clade, while most of the hospital-associated strains were collected in the G1 clade. However, no difference was found between the community and hospital-associated strains according to PFGE results. Simultaneously, other microorganisms were also isolated from patients from which these 6 P. aeruginosa strains were isolated. Of these patients, 5 patients died, except the number 70.
Conclusions: The median length of stay (days) was found to be significantly higher in the group with HAI than in the group with CAI. Compared to sample 28 and 37, which carried 5 β-lactamase coding genes, the death of these 5 patients with fewer or no resistance genes showed that the coexistence of other factors - especially other microorganisms in addition to resistance genes, was important.