Experience with infections involving the rare non-fermenter Alcaligines faecalis

Authors:
Pooja Ajith, Saron Araya, Sridha Gona, Aaron George, Hugo Bonatti

Body of Abstract:
Background: Alcaligines faecalis is a rare non-fermentative Gram-negative rod found in water and soil and decaying material. Other previous Alcaligines spp recently underwent reclassification within the Burkholderiales order such as Achromobacter xyloxidans. Up to 25% of humans are colonized with the organism and only a limited number of infections have been published with the majority diagnosed in immunocompromised individuals.

Methods: Our institutional database was searched for all infections caused by Alcaligines faecalis during a 4-year period. Two isolates initially reported as Alcaligines xyloxidans were excluded from the study.

Results: In total 38 isolates in 33 patients were identified. Median age was 60 (range 35.3-95.6) years; 63.6% were male. Rates of comorbid conditions were DM 46%, hypertension 399%, hyperlipidemia 36%, COPD 21%, CAD 18%, and malignancies 15%. 46% of individuals were obese and 61% were active smokers. Demographic, clinical, and microbiology data are shown in table 1. Bacterial growth pattern based on streak appearance for surgical specimens was reported light in 30%, moderate in 13% and heavy in 57%; 70% of infections were polymicrobial with staphylococci in 43%, streptococci in 13%, Gram-negative rods in 28%, and anaerobes in 18% as co-pathogens. Blood cultures accounted for 6%, drainage fluids/tissue specimens for 42% and wound cultures for 42% of specimens, 9% came from drained abscesses. Only 6% of isolates came from blood cultures. Alcaligines faecalis was predominantly isolated in lower extremity soft tissue infections (88%), upper extremities were involved in 3% and another 3% were intraabdominal infections. Surgical services submitted 33% of specimens, medical services including infectious diseases 27% and the emergency department 27%; 12% of specimens came from primary care physicians. Treatment for surgical infection included incision and drainage, debridement and amputation as indicated together with antibiotics according to sensitivity testing considering the high rate of mixed infections.

Conclusion: Alcaligines faecalis in this series was predominantly isolated in patients with chronic lower extremity infections such as diabetic foot syndrome. Whereas the majority of these infections were treated successfully, patients with Alcaligines faecalis infections had a survival of only 73% after a 2-year follow-up reflecting the high rates of comorbidities in these individuals.