Rare but Risky: Orthopedic Infections by Unconventional Gram-Positive Cocci - A Case Series

Staphylococcus aureus is the most common Gram-positive cocci causing orthopedic infections. However, infections due to unconventional Gram-positive cocci (GPC) are also occasionally reported. In such cases, the isolated microorganisms are usually a part of normal flora of human body turned into opportunistic pathogens. We have reported that three cases where the infection was due to such unconventional GPC.

Case 1: An 81-year-old man presented with collection of fluid at operative site after 1 month of operation. Staphylococcus warneri was isolated from the drain fluid of postoperative site. The wound was completely healed after treatment with linezolid and levofloxacin for 2 weeks. Case 2: A 54-year-old woman presented with lacerated wound on the left knee, difficulty in walking and cellulitis. There was a history of roadside accident 5 days ago. Gemella morbillorum was isolated from the pus swab of the wound. It was successfully treated with linezolid for 3 weeks and regular dressings. Case 3: A 48-year-old woman presented with left fourth toe swelling and pain. On examination, there was cellulitis of 4th toe with query pre-gangrenous changes. The slough of the affected toe was removed under anesthesia and sent for culture. Enterococcus casseliflavus was isolated from the sample. Complete healing of the infection was seen after 3 weeks' duration of treatment with levofloxacin and supportive treatment. In these three cases, uncommon GPC were isolated. There was clinical correlation for infection in all cases. After discussing with the microbiologist, antibiotic therapy was modified in these cases as per the culture and sensitivity report. Antibiotic treatment along with surgical intervention led to satisfactory wound healing and clinical improvement in these patients.

Infections due to unconventional organisms are rarely encountered in orthopedic patients. High index of suspicion of the infection, standard protocols of culture and clinical correlation of the laboratory reports play important role in dealing with these infections. These rare organisms should not be overlooked as contaminants. Furthermore, antimicrobial stewardship is helpful for better antimicrobial utilization.