Eikenella corrodens causing deep-seated infections. Six-year experience in a Spanish University Hospital.

L. Rodríguez-Rojas, A. Suárez-López, P. Ruiz-Garbajosa, M.A Messeguer, R. Cantón Microbiology Department. Ramón y Cajal University Hospital. Madrid. Spain

Introduction. Material and methods Results

Eikenella corrodens (EC) is part of the normal microbiota of the oropharynx and a A total of 48 patients infected with EC were identified, 9 of them with deep-seated recognised opportunistic pathogen. It is mainly involved in head and neck infections, but it infections. 6 were male, and mean age was 61 years (±12.25 SD). Antibiotic has been identified as a cause of pleuropulmonary and intraabdominal infections. susceptibility is shown in figure 1. Resolution of the infection was attained in all cases. Its identification could be difficult due to its fastidious growth, especially in the context of polymicrobial infections and is probably underreported. We describe the clinical and microbiological characteristics of 9 deep-seated infections caused by EC diagnosed in our laboratory. Antibiotic sensitivity (%)

EC isolates cultured from abscesses or usually sterile sites or fluids were identified from the 100 100 100 100 electronic database of our laboratory during the years 2010-2015. Patients’ clinical charts 85,7 85,7 85,7 were reviewed to assess patient’s medical history, infection characteristics, treatment, and 77,7 75 outcome (table 1). Susceptibility testing was performed by Etest (CLSI criteria).

Infection site Underlying disease Polymicrobial infection Previous surgery or Drai- Antibiotic invasive procedures nage treatment Liver abscess Diabetes mellitus, No Cephalic duodeno- Yes Piperacillin- pancreatic pancreatectomy tazobactam adenocarcinoma Intraabdominal Perforated colonic No - Yes Piperacillin- abscess adenocarcinoma tazobactam, gentamicin, Peritonitis Chronic kidney No Peritoneal dialysis No Levofloxacin, Figure 1: Antibiotic sensitivity of EC isolates obtained from deep-seated infections. disease catheter vancomycin Liver abscess No Laparoscopic Yes Piperacilin- cholecystectomy tazobactam Empyema Diabetes mellitus S. intermedius - Yes Piperacilin- Conclusions tazobactam Liver and psoas - Prevotella spp., - Yes Meropenem EC is characterised for its propensity toward formation of abscesses, causing indolent infections that can progress and cause severe diseases. When causing deep-seated abscess, Fusobacterium spp. infections it is normally associated with other organisms, but its virulence appears to empyema be significant regardless of the presence of coinfecting . Empyema Alcohol abuse, Streptococcus spp., - No Ertapenem In the present study we found that a break in mucocutaneous barriers (invasive Corynebacterium spp. procedures or surgery) could be a risk factor for infection with EC. Empyema Morbid obesity, post- No Bariatric surgery, Yes Piperacillin- It is resistant to antimicrobials usually prescribed for abscesses, such as surgery endotracheal tazobactam and metronidazole, and is prone to cause relapses if it is not treated properly. The 9 intubation cases presented here were successfully treated with β-lactams (piperacillin- Empyema Oesophageal cancer No Oesophagectomy Yes Meropenem, tazobactam or carbapenems) either alone or combined with levofloxacin or gentamicin. linezolid

Table 1: Clinical characteristics, treatment and outcome of deep-seated EC infections.