Natural antimicrobial susceptibility patterns and biochemical profiles of Leclercia adecarboxylata strains

Abstract

Leclercia adecarboxylata is an opportunistic human pathogen that phenotypically resembles Escherichia coli. The natural susceptibilities of 101 Leclercia strains to 70 antimicrobial agents were investigated. MICs were determined with a microdilution procedure in cation-adjusted Mueller-Hinton broth (all strains) and IsoSensitest broth (some strains). Natural susceptibility patterns were assessed using German (DIN) standards (when applicable). In addition, biochemical properties recommended for the phenotypic identification of L. adecarboxylata were evaluated, applying two commercially available identification systems for Enterobacteriaceae and seven conventional tests. L. adecarboxylata strains were naturally sensitive to tetracyclines, aminoglycosides, all but two beta-lactams, quinolones, folate pathway inhibitors, chloramphenicol, nitrofurantoin and azithromycin. They were naturally resistant to penicillin G, oxacillin, erythromycin, roxithromycin, clarithromycin, ketolides, lincosamides, streptogramins, linezolid, glycopeptides, rifampicin, fusidic acid and fosfomycin. There were only minor medium-dependent differences in susceptibility to most antibiotics. Lysine decarboxylase, malonate assimilation and acid production from arabitol and cellobiose, but not from adonitol and sorbitol, allowed definitive separation of L. adecarboxylata from E. coli. The results of this study form a database that can be applied to validate forthcoming antibiotic susceptibility tests of L. adecarboxylata, and might contribute to its reliable identification. Susceptibility patterns did not indicate obvious therapeutic difficulties for treatment of Leclercia infections. Special attention should be paid to biochemically aberrant leclerciae. Apart from biochemical features, fosfomycin susceptibility might be useful to differentiate between L. adecarboxylata and E. coli.

Peritonitis by Leclercia adecarboxylata in a patient with continuous ambulatory peritoneal dialysis: the first case report from India

“…12 Stock et al studied the natural antimicrobial susceptibility pattern of 101 strains and showed that all of them were naturally sensitive to all tested aminoglycosides. 13 Our isolate was however resistant to gentamicin and tobramycin but sensitive to amikacin. The dialysis-related infections update recommends an aminoglycoside or a third generation cephalosporin such as ceftazidime or cefepime or a carbapenem for gram negative coverage.…”

Leclercia adecarboxylata, a rare cause of soft tissue infections in immunocompromised patients, case report and review of the literatura

“…Leclercia adecarboxylata, described by Leclerc in 1962 and first designated as "Enteric group 41" or "Escherichia adecarboxylata", is a Gram-negative, oxidase-negative, indole-positive, facultative-anaerobic, motile bacillus, member of the Enterobacteriaceae family, that is phenotypically similar to Escherichia coli 1,3,7 ; it was differentiated in 1986 by Tamura et al through DNA hybridization, biochemical and computer iden- . L. adecarboxylata is thought to be distributed widely in nature, present in food, water sources, egg shells, milk, industrial fat and oil reservoirs and as a commensal of the gut flora of some animals 1,3,[7][8][9] ; it has also been recovered, uncommonly, from human samples like blood, bone 10 , cardiac valve, wounds, bronchial wash 11 , peritoneal fluid, urine, gall bladder, synovial fluid, abscesses and epididymo-orchitis, from immunocompromised and immunocompetent patients, being the former the most relevant and frequent scenario, as the case of our patient, and the later generally but not always associated to polymicrobial infections, suggesting the dependence of this bacteria on other microorganisms to infect immunocompetent hosts 1,7 .…”

“…L. adecarboxylata is thought to be distributed widely in nature, present in food, water sources, egg shells, milk, industrial fat and oil reservoirs and as a commensal of the gut flora of some animals 1,3,[7][8][9] ; it has also been recovered, uncommonly, from human samples like blood, bone 10 , cardiac valve, wounds, bronchial wash 11 , peritoneal fluid, urine, gall bladder, synovial fluid, abscesses and epididymo-orchitis, from immunocompromised and immunocompetent patients, being the former the most relevant and frequent scenario, as the case of our patient, and the later generally but not always associated to polymicrobial infections, suggesting the dependence of this bacteria on other microorganisms to infect immunocompetent hosts 1,7 .…”

“…To our knowledge, our patient is the first report of infection by Leclercia adecarboxylata after a trauma with plant material (logs), in an immunocompromised patient (Diabetes Mellitus type 2), not associated to other microorganisms, successfully treated with a course of 10 days of Ampicillin/Sulbactam 1.5 grams IV every 6 hours for 10 days. L. adecarboxylata has natural resistance to fosfomycin 3 . Natural resistance of L. adecarboxylata to fosfomycin may represent an additional parameter for its reliable phenotypic separation from E. coli.…”

“…It is thought to be present widely in nature and it is a rare cause of disease in humans, with an antimicrobial susceptibility ranging from natural resistance to multiple antibiotics 3 , to multidrug resistance due to the production of several enzymes [4][5][6] . We report the first known case of infection by this microorganism related to trauma with plant material, a review of reported cases around the world with interesting clinical manifestations, natural antimicrobial susceptibility and acquired resistance patterns are also presented.…”