A series of Haemophilus parainfluenzae surgical infections

Hugo Bonatti, University of Maryland Shore Health; Rosa Mateo, University of Maryland Shorehealth

Haemophilus parainfluenzae (H.PI) is a rare pathogen, however, recent reports emphasize that the organism may be underreported. It is part of the HAKEC group and associated with endocarditis. Even less information about H.PI is available for surgical infections, especially in patients with intraabdominal infections, the vast majority being case reports.

Haemophilus parainfluenzae may be an under-diagnosed and/or under-reported pathogen in surgical infections.

We herein report a series of patients with H.PI surgical infections from a rural hospital. Isolation and identification of the pathogen was done according to standard guidelines. A total of 273 isolates were analyzed, there were 15 patients with double isolation. In the majority of cases H.PI was part of a mixed infection.

A total of 34 patients with 36 isolates with surgical infections with H.PI were identified during the 2 year study period. This represents 13.2% of all isolates of H.PI with 64.8% coming from patients with respiratory tract infections, 17.9% from patients with ENT/Eye infections, 3% from genital/urologic infections and the remaining 3 (1%) were from positive blood cultures. Within the surgical infections, the majority of isolates came from skin/soft tissue infections (n=28) including abscesses of the upper extremities (n=14), lower extremities (n=5), face (2) and other sites (n=7). There were two cases of bone infection (one associated with an infected hip replacement), two perirectal abscesses and one infected hemodialysis catheter. The remaining three patients had abdominal infections including one perforated appendicitis, one perforated diverticulitis and one pelvic abscess 10 days after laparoscopic appendectomy. In all three cases a percutaneous drain was placed and all abdominal infections were controlled with intravenous antibiotic therapy. In all three cases H.PI was part of a mixed infection. Our H.PI isolates in general were found to be negative for betalactamase production.

This is the largest thus far reported series of H.PI isolates. The exact significance of our findings cannot be determined at this stage especially as most isolates were from mixed infections. Nevertheless, more research with regard to this elusive pathogen is warranted.