Inducible Antibiotic Resistance in Aeromonas Hydrophilia Leading to Necrotizing Fasciitis, Complete Forequarter Amputation, and Death
CCCF ePoster library. Katz D. Nov 1, 2016; 150963; 82
David Katz
David Katz
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Topic: Clinical Case Report

Inducible Antibiotic Resistance in Aeromonas Hydrophilia Leading to Necrotizing Fasciitis, Complete Forequarter Amputation, and Death

Katz, David1; Poutanen, Susan M.2; Lee, Christie1
1Interdepartmental Division of Critical Care, University of Toronto, Toronto, Canada; 2Division of Infectious Diseases, University of Toronto, Toronto, Canada


Aeromonas Hydrophilia is a pathogenic water-borne gram-negative bacillus. It has been reported to cause human infections including gastroenteritis and soft tissue infections, ranging in spectrum from cellulitis to necrotizing fasciitis.1 Several case reports of Aeromonas species causing necrotizing fasciitis have previously been reported2,3, and genetic analyses of different strains has illustrated differing mechanisms of antibiotic resistance.4 One such mechanism includes inducible beta-lactamase production, however it has not been clinically relevant as induction typically takes place at temperatures below the physiologic range.5 The following report illustrates a case of inducible antibiotic resistance, in Aeromonas Hydrophilia, causing severe necrotizing fasciitis, leading to fore-quarter amputation and ultimately death.
To illustrate the first report of clinically relevant inducible antibiotic resistance in Aeromonas species, leading to critical illness and death.
A 62-year old male was transferred to the Intensive Care Unit from an In-patient Oncology Centre for septic shock one week after having received chemotherapy for a new diagnosis of mixed phenotypic acute leukemia. Following initiation of empirical, broad-spectrum antibiotics, blood cultures revealed a bacteremia with a fully-sensitive Aeromonas Hydrophilia.  Treatment was narrowed to Ceftriaxone.  Hemodynamic stability was achieved and he was transferred back to the In-patient Oncology Centre.
Four days after ICU discharge, he was noted to be in profound septic shock necessitating mechanical ventilation, inotropic support and transfer back to the Intensive Care Unit. At the time it was observed that his left arm had large areas of necrotic skin and was extremely painful. Antibiotic coverage was broadened and Orthopedic Surgery was consulted for concerns of necrotizing fasciitis. His clinical status deteriorated and a complete left fore-quarter amputation was performed as treatment for necrotizing fasciitis. Pathologic analysis confirmed necrotizing fasciitis with Aeromonas Hydrophilia. Repeat sensitivity testing revealed that the micro-organism had developed resistance to beta-lactam antibiotics notwithstanding its initial sensitivity to these agents (Table 1).
Despite surgical intervention and appropriate antibiotic coverage, the patient began exhibiting signs of necrotizing fasciitis spreading across the anterior chest wall. He progressed to multi-organ failure and ultimately died of necrotizing fasciitis from Aeromonas Hydrophilia that developed inducible beta-lactam resistance. This phenomenon of clinically relevant inducible beta-lactam resistance has not been previously reported in the literature.
This case illustrates the first described instance of an Aeromonas species bacterium exhibiting inducible antibiotic resistance in a clinical setting. The induction of antibiotic resistance to initial cephalosporin treatment lead to further bacteremia, septic shock, necrotizing fasciitis, and ultimately death. This may represent an inducible beta-lactamase resistance that has escaped its previously described temperature sensitivity or perhaps a new mechanism of antibiotic resistance not previously seen in Aeromonas species. Microbiologic samples have been sent for further genetic analysis to determine the mechanism of resistance and results are pending.


1.     Gold WL, Salit IE. Aeromonas hydrophila infections of skin and soft tissue: report of 11 cases and review. Clin Infect Dis. 1993;16(1):69-74.
2.     Borger van der Burg BLS, Bronkhorst MWGA, Pahlplatz PVM. Aeromonas hydrophila necrotizing fasciitis. A case report. J Bone Joint Surg Am. 2006;88(6):1357-1360.
3.     Minnaganti VR, Patel PJ, Iancu D, Schoch PE, Cunha BA. Necrotizing fasciitis caused by Aeromonas hydrophila. Heart Lung. 2000;29(4):306-308.
4.     Grim CJ, Kozlova EV, Ponnusamy D, et al. Functional genomic characterization of virulence factors from necrotizing fasciitis-causing strains of Aeromonas hydrophila. Appl Environ Microbiol. 2014;80(14):4162-4183.
5.     Walsh TR, Stunt RA, Nabi JA, MacGowan AP, Bennett PM. Distribution and expression of beta-lactamase genes among Aeromonas spp. J Antimicrob Chemother. 1997;40(2):171-178.

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