Extragenital Mycoplasma hominis infection in two liver transplant recipients.

Mycoplasma hominis has been recognized as an extragenital pathogen in immunocompromised hosts, including kidney and heart transplant recipients; patients with systemic autoimmune diseases, lymphomas, or leukemia; and patients who have undergone cardiac surgery or who have experienced trauma [1, 2]. Liver transplantation has rarely been reported to increase host susceptibility to intraabdominal M hominis infection [1, 3, 4]. We describe two liver transplant recipients with extragenital M. hominis infection, and we emphasize the need for physicians to be aware of the pathogenicity of M. hominis for this group of patients. The isolation of M. hominis from the pleural space and the abdominal surgical wound in the first case and from an intrahepatic abscess in the second one indicates that M hominis infection in sites other than the peritoneal cavity should be considered. We furthermore propose the use of sequence determination of the tuf gene [5-7] for rapid species diagnosis to accelerate clinical decisions. A 48-year-old male patient underwent orthotopic liver transplantation for treatment of hepatocellular carcinoma and liver cirrhosis associated with hepatitis B virus. The patient developed fever, pleural effusions, and signs of abdominal surgical wound infection in the fifth week after transplantation. The results of standard bacteriologic examination of the pleural fluid and of wound swabs were unremarkable; after 3-4 days, translucent pinpoint colonies appeared on Columbia agar and on chocolate agar. Subculture on supplemented mycoplasma agar (Oxoid, Basingstoke, UK) revealed colonies with the "fried-egg" appearance that is typical for mycoplasmas after 2 days. Before specific antibiotic therapy could be initiated, the patient developed fulminant and fatal Klebsiella oxytoca pneumonia that did not respond to initial treatment with piperacillin and tobramycin. The mycoplasma isolates were nonglycolytic and hydrolyzed arginine. The isolates were confirmed to be M hominis by amplification of the gene encoding the elongation factor Tu (tuf) and by direct sequence determination of the PCR product as described previously [5-7]. Although the clinical relevance of the pleural and wound infection remained unclear in this patient's case, our experience prompted us to culture relevant extragenital specimens obtained from liver transplant recipients in mycoplasma agar (this agar was used in addition to standard diagnostic culture media). The value of using this agar was confirmed since 2 months later M hominis was isolated from swab specimens from the peritoneal cavity of a female 29-year-old drug addict who had heptitis B virus—induced acute liver failure that had been treated by liver transplantation. Peritonitis and fever had developed 4 weeks after transplantation due to partial necrosis of the bile duct, which was treated surgically by a hepatojejunostomy.