<i>Acinetobacter</i> Non-<i>baumannii</i> Species: Occurrence in Infections in Hospitalized Patients, Identification, and Antibiotic Resistance

• Main Authors: Eugene Sheck (Author), Andrey Romanov (Author), Valeria Shapovalova (Author), Elvira Shaidullina (Author), Alexey Martinovich (Author), Natali Ivanchik (Author), Anna Mikotina (Author), Elena Skleenova (Author), Vladimir Oloviannikov (Author), Ilya Azizov (Author), Vera Vityazeva (Author), Alyona Lavrinenko (Author), Roman Kozlov (Author), Mikhail Edelstein (Author)
• Format: Book
• Published: MDPI AG, 2023-08-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Background: <i>Acinetobacter</i> species other than <i>A. baumannii</i> are becoming increasingly more important as opportunistic pathogens for humans. The primary aim of this study was to assess the prevalence, species distribution, antimicrobial resistance patterns, and carbapenemase gene content of clinical <i>Acinetobacter</i> non-<i>baumannii</i> (<i>Anb</i>) isolates that were collected as part of a sentinel surveillance program of bacterial infections in hospitalized patients. The secondary aim was to evaluate the performance of MALDI-TOF MS systems for the species-level identification of <i>Anb</i> isolates. Methods: Clinical bacterial isolates were collected from multiple sites across Russia and Kazakhstan in 2016-2022. Species identification was performed by means of MALDI-TOF MS, with the Autobio and Bruker systems used in parallel. The PCR detection of the species-specific <i>bla</i>_OXA-51-like gene was used as a means of differentiating <i>A. baumannii</i> from <i>Anb</i> species, and the partial sequencing of the <i>rpoB</i> gene was used as a reference method for <i>Anb</i> species identification. The susceptibility of isolates to antibiotics (amikacin, cefepime, ciprofloxacin, colistin, gentamicin, imipenem, meropenem, sulbactam, tigecycline, tobramycin, and trimethoprim-sulfamethoxazole) was determined using the broth microdilution method. The presence of the most common in <i>Acinetobacter</i>-acquired carbapenemase genes (<i>bla</i>_OXA-23-like, <i>bla</i>_{OXA-24/40-like}, <i>bla</i>_OXA-58-like, <i>bla</i>_NDM, <i>bla</i>_IMP, and <i>bla</i>_VIM) was assessed using real-time PCR. Results: In total, 234 isolates were identified as belonging to 14 <i>Anb</i> species. These comprised 6.2% of <i>Acinetobacter</i> spp. and 0.7% of all bacterial isolates from the observations. Among the <i>Anb</i> species, the most abundant were <i>A. pittii</i> (42.7%), <i>A. nosocomialis</i> (13.7%), the <i>A. calcoaceticus/oleivorans</i> group (9.0%), <i>A. bereziniae</i> (7.7%), and <i>A. geminorum</i> (6.0%). Notably, two environmental species, <i>A. oleivorans</i> and <i>A. courvalinii</i>, were found for the first time in the clinical samples of patients with urinary tract infections. The prevalence of resistance to different antibiotics in <i>Anb</i> species varied from <4% (meropenem and colistin) to 11.2% (gentamicin). Most isolates were susceptible to all antibiotics; however, sporadic isolates of <i>A. bereziniae</i>, <i>A. johnsonii</i>, <i>A. nosocomialis</i>, <i>A. oleivorans</i>, <i>A. pittii</i>, and <i>A. ursingii</i> were resistant to carbapenems. <i>A. bereziniae</i> was more frequently resistant to sulbactam, aminoglycosides, trimethoprim-sulfamethoxazole, and tigecycline than the other species. Four (1.7%) isolates of <i>A. bereziniae</i>, <i>A. johnsonii</i>, <i>A. pittii</i> were found to carry carbapenemase genes (<i>bla</i>_OXA-58-like and <i>bla</i>_NDM, either alone or in combination). The overall accuracy rates of the species-level identification of <i>Anb</i> isolates with the Autobio and Bruker systems were 80.8% and 88.5%, with misidentifications occurring in 5 and 3 species, respectively. Conclusions: This study provides important new insights into the methods of identification, occurrence, species distribution, and antibiotic resistance traits of clinical <i>Anb</i> isolates.

Item Description

10.3390/antibiotics12081301
2079-6382