Taxonomy, virulence determinants and antimicrobial susceptibility of Aeromonas spp. isolated from bacteremia in southeastern China

Abstract

Background The study aimed to elucidate the species taxonomy, clinical manifestations, virulence gene profiles and antimicrobial susceptibilities of Aeromonas strains isolated from life-threatening bacteremia in southeastern China. Methods Clinical samples of Aeromonas causing bacteremia were isolated from a teaching hospital in Wenzhou from 2013 to 2018 and a retrospective cohort study was performed. Aeromonas strains were identified at species level by housekeeping gene gyrB. Virulence and drug resistance-associated genes were screened by polymerase chain reaction (PCR) and antimicrobial susceptibility testing (AST) was performed by the VITEK 2 Compact system. Results A total of 58 Aeromonas isolated from patients with bacteremia were collected during 6 years (2013–2018). 58 isolates were identified to five different species, where Aeromonas dhakensis appeared to be the predominant species (26/58), followed by Aeromonas veronii (13/58), Aeromonas caviae (10/58), Aeromonas hydrophila (7/58) and Aeromonas jandaei (2/58). 16 of 58 patients had poor prognosis. Poor prognosis was significantly associated with liver cirrhosis and inappropriate empirical antimicrobials therapy. The progression of bacteremia caused by Aeromonas was extremely fast, especially in A. dhakensis infections. Virulence genes aer, lip, hlyA, alt, ast, and act, were detected at ratios of 24.1% (14/58), 62.1% (36/58), 65.5% (38/58), 58.6% (34/58), 15.5% (9/58) and 65.5% (38/58), respectively. Antimicrobial susceptibility testing exhibited that 9 out of 58 isolates were identified as multi-drug resistant (MDR) organism. The blaTEM gene was identified in all 9 MDR isolates. blaSHV, blaAQU-1, blaMOX, blaCepH, blaCphA and aac(6′)-Ib-cr were detected in 4 isolates, 2 isolates, 1 isolate, 3 isolates, 8 isolates, and 3 isolates, respectively. The majority of Aeromonas strains maintained susceptible to 3rd generation cephalosporins, aminoglycosides, fluoroquinolones and furantoin. Conclusions The prevalence and dangerousness of Aeromonas infections, especially A. dhakensis, are underestimated in clinic. Continuous monitoring is essential to keep track of MDR Aeromonas due to the increasing prevalence recently and a more effective measure is required to control the spread of resistance determinants.

Aeromonas dhakensis: Clinical Isolates with High Carbapenem Resistance

“…Further investigation of the genetic background of carbapenem resistant isolates in our study revealed a chromosomally encoded metallo-β-lactamase cphA gene, indicating that these clinical isolates are attributed to intrinsic resistance. This finding is in agreement with previously published reports on A. dhakensis isolated from human infections in Australia [ 19 ], Taiwan [ 20 ] and China [ 21 ]. The results suggest that clinical use of carbapenem monotherapy should be considered with caution in order to avoid potential treatment failure and that alternative antimicrobial treatment options, such as fourth-generation cephalosporins, quinolones, amikacin, aztreonam and trimethoprim/sulfamethoxazole, remain active for most A. dhakensis isolates.…”

Accurate Identification and Virulence Detection of <i>Aeromonas</i>: a Single-Center Retrospective Study on the Clinical Features and Outcomes Associated with <i>Aeromonas</i> Bacteremia in Southwestern China

“…VITEK MS system was also shown to be insufficient for correctly identifying Aeromonas species. A recent study (26) found that VITEK MS system and housekeeping gene sequencing had a 53.4% coincidence rate.…”

“…in Zhejiang, China, with a fatality rate of 46.15% (26). Aeromonas caviae was the most common strain (34), with a 17% mortality rate in Japan.…”

A novel detection method for the pathogenic Aeromonas hydrophila expressing aerA gene and/or hlyA gene based on dualplex RAA and CRISPR/Cas12a

“…at room temperature and low temperature (Balakrishna et al, 2010;Janda and Abbott, 2010), and produce virulence factors aerolysin and/or hemolysin (Wong et al, 1998;Heuzenroeder et al, 1999;Balakrishna et al, 2010;Janda and Abbott, 2010). Patients infected with A. hydrophila can develop sepsis and necrotizing fasciitis, which have an acute onset and rapid progression (Tsai et al, 2015;Sun et al, 2021) and are lifethreatening, mainly through ingestion of contaminated water and food and exposed wounds, respectively (Meng et al, 2015); moreover, sepsis can reach a state of systemic toxicity within 24 h (Zhu et al, 2021). In view of these aspects, a rapid, accurate, and sensitive detection method of pathogenic A. hydrophila would contribute to improving the treatment and control strategies and then reducing the hazard of this bacterial infection.…”