Aeromonas dhakensis as an emerging invasive pathogen: a case series highlighting distinct carbapenem resistance and diagnostic challenge.

BACKGROUND

Aeromonas dhakensis is an emerging and potentially more virulent species within the Aeromonas genus, frequently misidentified in routine laboratories, leading to underrecognition and suboptimal management.

OBJECTIVES

To describe the clinical spectrum, laboratory characteristics, and antimicrobial susceptibility patterns of A. dhakensis isolated from clinically significant specimens in a tertiary-care setting.

METHODS

A retrospective case series was conducted at a tertiary-care teaching hospital during November-December 2025. Clinical and microbiological records of patients with A. dhakensis isolated from clinically relevant specimens were reviewed. Species identification was performed using MALDI-TOF MS with updated databases, and antimicrobial susceptibility testing was interpreted according to CLSI guidelines.

RESULTS

Four cases of clinically significant A. dhakensis infection were identified (median age 43 years), involving pleural fluid, pus aspirate, endotracheal aspirate, and urine. Clinical presentations included hydropneumothorax, breast abscess, neurosurgical complications, and urinary tract infection. Two patients required ICU care and mechanical ventilation. Laboratory findings showed mild anemia and leukocytosis in select cases. All isolates demonstrated uniform resistance to carbapenems and piperacillin-tazobactam, while retaining susceptibility to fluoroquinolones, aminoglycosides, third- and fourth-generation cephalosporins, aztreonam, trimethoprim-sulfamethoxazole, and doxycycline. All patients improved with appropriate therapy and survived to discharge.

CONCLUSION

A. dhakensis is an emerging invasive pathogen with a characteristic resistance profile marked by intrinsic carbapenem resistance. Accurate species-level identification using MALDI-TOF MS and susceptibility-guided therapy are essential. This study provides region-specific evidence highlighting the need for increased clinical awareness, diagnostic stewardship, and surveillance.