Requiring Reconsideration of Differences of Aeromonas Infections Between Extra-Intestinal and Intestinal in Hospitalized Patients

Abstract

Purpose

The purpose of this study is to examine the variations between extra-intestinal and intestinal infections of Aeromonas in terms of strain types, risk factors, drug susceptibility results, and the distribution of drug resistance and virulence genes.

Patients and Methods

A total of 188 Aeromonas strains were identified to the species level using housekeeping genes (rpoD, gyrB, and gyrA). The risk factors for Aeromonas extra-intestinal and intestinal infection, as well as mortality, were retrospectively examined in this study. The broth microdilution method was used to investigate the antimicrobial susceptibility profiles. Touchdown polymerase chain reaction (PCR) assays and DNA sequencing were employed to confirm virulence and the presence of drug resistance genes.

Results

The housekeeping genes identified 188 strains into 7 species. Extra-intestinal isolates generally contained A. caviae and A. hydrophila, while intestinal were A. veronii (p=0.0001). Extra-intestinal infections (158/188) were the main type and accounted for 24/27 of all fatalities. Malignant tumors, hepatobiliary diseases, anemia, and hypoproteinemia were linked to infections. Poor results were associated with septic shock. Using the broth microdilution method, over 80% isolates were susceptible to most antimicrobials, except for ceftazidime (79.8%) and ceftriaxone (69.7%). Except for imipenem, intestinal strains were more susceptible to other medications than extra-intestinal. Using touch-down polymerase chain reaction testing and DNA sequencing, 6 strains, 31 strains, and a strain only had bla_TEM, bla_CphA, and bla_VIM, respectively. Two Aeromonas hydrophila each possessed bla_CphA+ bla_CTXM-M-9, and bla_CphA + bla_CTX-M-1 + bla_{CTX-M-15-like} + bla_TEM; two Aeromonas caviae each possessed bla_NDM + bla_CTX-M-1 +bla_{CTX-M-15-like} + bla_TEM, and bla_NDM + bla_TEM. Thirty-four of the 42 strains mentioned above were isolated from extra-intestinal. Act, aexT, and ascF-G, were in intestinal more frequently, but alt, hlyA, ela, and lip were in extra-intestinal more frequently.

Conclusion

Aeromonas inside and outside intestinal differed in their clinical characteristics, drug susceptibility, drug resistance and virulence genes.

Keywords:

• intestinal and extra-intestinal infections
• Aeromonas
• risk factor
• virulence

Ethics Approval

This study was performed in line with the principles of the Declaration of Helsinki. The collection of culture isolates and collation of anonymous clinical data was in accordance with the approved clinical practice guidelines. Approval was granted by the Institutional Review Board and Ethics Committee of Chongqing Medical University approved this study (approval number: KY2021-557).

Acknowledgments

The authors would like to thank all participants and data collectors.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work was supported by the Natural Science Foundation of Chongqing (No. cstc2019jcyj-msxmX0253). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.