Asymptomatic Bacteriuria Caused by Haemophilus influenzae in a Kidney Transplant Recipient

ABSTRACT

Haemophilus influenzae has rarely been implicated as the causative agent of urinary tract infections (UTIs). However, cases of UTIs caused by H. influenza in patients with anatomical or functional urinary tract abnormalities have been steadily reported. We report a case of asymptomatic bacteriuria caused by H. influenzae in a kidney transplant recipient. The patient was a 61-yr-old woman who visited the hospital for a routine follow-up after receiving a kidney transplant from a living-related donor; the patient showed no symptoms. Urine microscopy revealed white blood cell (WBC) count of >30/high power field (HPF). Urine culture on blood agar showed non-hemolytic, tiny, translucent, grayish colonies with satellitism around beta-hemolytic colonies of Staphylococcus epidermidis. The organism in the satellite colonies was identified as H. influenzae by using VITEK Neisseria/Haemophilus Identification Card (bioMerieux, Marcy L'Etoile, France) and found to require both X and V factors for growth. The organism did not produce beta-lactamase. Urine culture performed 1 week later revealed H. influenza again. The patient was not treated with antimicrobials. Urine culture performed using chocolate agar 7 weeks later did not reveal H. influenzae. Since H. influenzae does not grow in the media commonly used for urine culture such as blood agar, the use of these media could lead to underestimation of the true frequency of H. influenzae. If UTI is suspected in a patient with anatomical or functional urinary tract abnormality, chocolate agar should be considered for urine culture.