Prevalence and Carbapenem Resistance of Acinetobacter baumannii and Other Than A. baumannii Isolates From Intensive Care Units (ICUs) and non-ICUs

Abstract

Background:Acinetobacter spp are gram-negative bacteria that have emerged as a leading cause of hospital-associated infections, most often in the intensive care unit (ICU) setting. This is particularly important in Poland, where the prevalence of A. baumannii in various types of infections, including bloodstream infection (BSI), pneumonia, skin and soft-tissue infection (SSTI), and urinary tract infection (UTI) is higher than in neighboring countries. Recently, other Acinetobacter spp, including A. lwoffii or A. ursingii, have been found to be clinically relevant. In Poland, we have also observed a very rapid increase in antimicrobial resistance, significantly faster for A. baumannii than for other nosocomial pathogens. Methods: A study was conducted in 12 southern Polish hospitals, including 3 ICUs, from January 1 to December 31, 2018. Only adult hospitalized patients were included. Strains were identified using the MALDI-TOF method. Carbapenem resistance was determined using the minimum inhibitory concentration (MIC). Results: During the study, 194 strains belonging to the Acinetobacter genus were isolated. A. baumannii was the dominant species, 88.1% (n = 171), and 23 isolates (11.9%) were other Acinetobacter spp: A. ursingii (n = 5), A. lwofii (n = 4), A. haemolyticus (n = 4), A. junii (n = 3), A. radioresistens (n = 2), A. bereziniae (n = 2), and A. johnsonii (n = 2). Moreover, 15 Acinetobacter strains were collected from ICUs. The most Acinetobacter strains were isolated from SSTIs (n = 115) from non-ICU settings. Non–A. baumannii strains were also most frequently isolated from SSTIs; they constituted 11.3% of all Acinetobacter strains from this type of infection (n = 13). The total Acinetobacter prevalence was 2.6%, whereas the prevalence in the ICU setting was 7%. Acinetobacter prevalence in SSTIs was 10.4%. In pneumonia, Acinetobacter prevalence was 18.6% for ICUs (n = 13) and 2.7% for non-ICUs (n = 46). Strains from UTIs were isolated only with the non-ICU setting, and their prevalence was 0.7% (n = 14). More than half of the tested strains (52.1%) were resistant to carbapenems, but all non–A. baumannii strains were susceptible. The highest resistance to carbapenems was among strains from pneumonia cases in ICUs (58.3%) and resistance among all strains isolated from ICU was 50%. However, even higher resistance was noted among SSTI strains from non-ICUs (61.7%). Conclusions: Increasingly, more than A. baumannii, other species among Acinetobacter strains are isolated from patients hospitalized in Polish hospitals. To assess the significance of non–A. baumannii spp in clinical settings, precise species identification is needed. Therefore, the diagnostic methods used must be improved. Carbapenem-resistant A. baumannii infections are the biggest problem in pneumonia patients in ICUs and in SSTI patients in other hospital departments. Carbapenem resistance occurs in a very high percentage of A. baumannii strains; among non–A. baumannii strains it is not yet a therapeutic problem.Funding: NoneDisclosures: None