Distribution and antimicrobial resistance of Acinetobacter spp. isolated from different types of clinical specimens from hospitalized patients and outpatients in Poland.

BACKGROUND

Acinetobacter baumannii (AB) is the most frequently isolated nosocomial pathogen, but severe infections by A. pittii, A. ursingii, and A. bereziniae are increasing. This study investigated the distribution and antibiotic resistance of Acinetobacter spp. strains from various clinical specimens.

METHODS

Data were collected between 2021-2023 from clinical samples of hospitalized and outpatient individuals in southern Poland. Strains were identified using MALDI-TOF Biotyper, and antibiotic susceptibility was tested with the MIDITECH-Analyzer system. Statistical analyses were conducted using IBM SPSS Statistics.

RESULTS

Among 1507 isolated Acinetobacter strains, 951 (63.1 %) were AB, while 556 (36.9 %) represented 27 non-AB species. Most isolates (73.6 %) came from outpatients, while 26.4 % were from hospitalized patients. A. ursingii (30.2 %), A. pittii (20.6 %), and A. junii (13 %) were the most common non-AB species. A. bereziniae, A. calcoaceticus, and A. proteolyticus were more frequently found in hospitalized patients. Non-AB species dominated in clinical specimens from genitourinary tract (87 %), whereas AB was more common in clinical specimens from invasive sites. Nearly all strains were non-susceptible to ciprofloxacin (98.4 %), with lower resistance rates to ampicillin/sulbactam (11.1 %), trimethoprim/sulfamethoxazole (5.8 %), gentamicin (2.9 %), amikacin (2.5 %), meropenem (1.6 %), and colistin (1.6 %). A. bereziniae showed frequently resistance to carbapenems, aminoglycosides, and trimethoprim/sulfamethoxazole. Colistin resistance was observed in A. ursingii and A. pittii.

CONCLUSIONS

While AB accounted for 63.1 % of isolates, non-AB species were common, particularly in clinical specimens from genitourinary tract and from skin and wound. Emerging hospital-acquired infections by species like A. pittii underline the need for vigilant monitoring. The high resistance to ciprofloxacin and low but noticeable resistance to carbapenems and colistin highlights the importance of early detection and resistance surveillance to prevent the spread of resistant strains.