Relevance of Achromobacter xylosoxidans in Non-Respiratory Tract Clinical Samples over a Decade (2008-2017): Findings from a Clinical Center in Southern Hungary

Aims: The genus Achromobacter includes lactose-non-fermenting Gram-negative bacteria that are aerobic, motile (with peritrichous flagella), oxidase and catalase-positive. To assess the prevalence of A. xylosoxidans isolated from non-respiratory tract samples from adult inpatients and outpatients and the antibiotic resistance levels at a tertiary-care teaching hospital in Szeged, Hungary retrospectively, during a 10-year study period.

Study Design: Retrospective microbiological study.

Place and Duration of Study: 1st of January 2008 - 31st of December 2017 at the University of Szeged, which is affiliated with the Albert Szent-Györgyi Clinical Center, a primary- and tertiary-care teaching hospital in the Southern Great Plain of Hungary.

Methodology: Data collection was performed electronically. Antimicrobial susceptibility testing (AST) was performed using disk diffusion method and when appropriate, E-tests on Mueller–Hinton agar plates.

Results: During the 10-year study period, a total of 68 individual A. xylosoxidans isolates were identified (6.8±3.6/year, range: 0-11 isolates). The frequency of isolation in the first half of the study period (2008-2017) was n=22, while in 2013-2017, this number was n=46. The majority of isolates (51 out of 68) were from inpatient departments. 32 out of 68 patients were female (female-to-male ratio: 0.89). The susceptibilities of the respective A. xylosoxidans isolates (n=68) were the following: high levels of susceptibility for imipenem and meropenem (n=63; 92.6%), and moxifloxacin (n=55; 80.9%), while higher rates of resistance were detected for sulfamethoxazole/trimethoprim (susceptible: n=36; 52.9%), ciprofloxacin (susceptible: n=40; 58.8%) and almost all isolates were resistant to ceftazidime (susceptible: n=3; 4.4%) and cefepime (n=2; 2.9%).

Conclusion: The existing literature on Achromobacter infections in the context of non-respiratory human infections is scarce, as the incidence of these pathogens in clinically-relevant syndromes in low. It should be noted, that the difficulty in the adequate identification (especially in low-resource settings) may be partly blamed for the infrequent characterization of these bacteria as significant pathogens. The developments in diagnostic technologies in routine clinical microbiology will probably lead to a shift in the isolation frequency of these bacteria in the future.