Skin and soft‐tissue infections associated with <i>Aeromonas</i> species in French Guiana: an 11‐year retrospective study

Abstract

Aeromonas species are Gram-negative bacilli, commonly found in salted and fresh water, food and soil.1 Skin and soft-tissue infections (SSTIs) are frequent2 and have been reported in Australia,1 Asia3 and the Indian Ocean.4 However, data from South America are scarce. We investigated the exposures, clinical characteristics and antimicrobial susceptibilities of Aeromonads involved in SSTIs in French Guiana. We looked for risk factors of unfavourable outcome. We retrospectively included all patients with skin or soft-tissue infections and a positive culture with Aeromonas spp, seen in the Cayenne Hospital between 2007 and 2018. A total of 81 patients were included. Clinical and epidemiological data are gathered in Table 1. Numbers of infections for each month of the year are presented in Fig. 1. The more frequent exposures were road trauma (n = 22) and snake bites (n = 16). Clinical presentations were often severe, including necrotizing fasciitis (n = 17) and abscesses (n = 15). Eleven patients required amputation. Antibiotic resistance profile was known for 77 patients (95%). Most strains were resistant to ticarcillin (72%). Less than 5% were resistant to ciprofloxacin, imipenem or gentamicin. None were resistant to ceftazidime or amikacin. Aeromonas hydrophila was the most common pathogen (n = 76, 94%). The majority of patients had polymicrobial infections, mostly with enterobacteriae (n = 27, 33%) and Staphylococcus aureus (n = 15, 19%). One half of monomicrobial infections (n = 18, 22%) were caused by snake bites. Concerning the outcome, two patients died, including a 61-year-old woman with A. hydrophila bacteraemia and a 71-year-old diabetic woman with a necrotizing fasciitis growing A. hydrophila and Klebsiella pneumonia. They both received amoxicillin–clavulanate though both germs were resistant. In multivariate analysis, the presence of burn as a route of entry (7 patients, 9%) was the only factor associated with unfavourable outcome (OR 6.54, 95% CI [1.13-37.95]). As in previous studies, A. hydrophila was the most common species responsible for skin and soft-tissue infection5 and infections occurred mostly during the rainy season.1, 6 The predominance of men and lower limbs is common in Aeromonads and should be linked to the role of outdoor activities as routes of entry. Among these exposures, burns were incriminated in 7 patients, possibly due to the use of contaminated water in primary care against burns.7 Aeromonas spp are a classic component of the oral microbiota8 of snakes, and we report here the largest series of Aeromonads infection after snake bite (n = 16, 20%).9 Concerning clinical features, the proportion of necrotizing fasciitis (n = 17, 21%) was higher than in most previous studies,5 excepting a report of Aeromonads infections after a tsunami in Thailand.3 This frequent severity could be explained by a delay in treatment due to a lack of healthcare access in remote areas of French Guiana. Though previous studies reported an important proportion of immunocompromised patients,2, 5 such a feature was not observed in our cohort. Thus, Aeromonads infections should also be expected in healthy young men performing at-risk outdoor activities. In multivariate analysis, burns were associated with unfavourable issue, mirroring previous case reports of high mortality in burned patients infected with Aeromonads.10 The only two deaths occurred when antibiotics were not adapted to antibiograms. These results highlight the importance of antibiotic stewardship in circumstances of burns, waterborne or telluric contaminations. Antibiotics covering Aeromonas and frequent co-pathogens should then be contemplated (third-generation cephalosporin or fluoroquinolone).2 Patients with burns in rainforest areas should be closely monitored due to the high risk of unfavourable outcome.

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