Occurrence and relevance of Gardnerella vaginalis in urine cultures of kidney transplant recipients- a retrospective cohort analysis.

BACKGROUND

Gardnerella vaginalis is known to be associated with the development of bacterial vaginosis. In contrast, its cultivation from urine specimen in significant number is not generally regarded as causative for urinary tract infections. In a previous study, we detected G. vaginalis predominantly in urine cultures of renal transplant recipients and questioned whether this is of relevance. To address this, we conducted a retrospective cohort study over a period of two years on renal transplant recipients who presented at the outpatient clinic of the Department of Nephrology of Heidelberg University Hospital. Patient characteristics and laboratory parameters of renal transplant recipients with G. vaginalis in urine cultures were compared to those of renal transplant recipients presenting in the same outpatient clinic with urine specimen culturing other bacteria than G. vaginalis, using a multivariable logistic regression analysis.

RESULTS

During the study period, G. vaginalis was detected in 70 urine samples of 38 patients. The majority of patients was female (86.8%, n = 33/38), and the age was significantly lower than in the control group (median 41 years and 51 years; OR 0.94, 95% CI 0.92-0.98, p = 0.001). a significant number of culture-forming units (CFU, ≥ 105 /ml) were detected in half of the samples containing G. vaginalis; a second microorganism was cultured in 64.3% (n = 45/70), while more than two species grew in 53.9% (n = 82/152) of the control group samples. Besides age, bacterial load of ≥ 105 CFU/ml was significantly associated the presence of G. vaginalis in urine cultures (OR 2.71, 95% CI 1.12-6.56, p = 0.003). The medical record was lacking information on clinical signs and symptoms of urinary tract infections.

CONCLUSION

As clinical symptoms were not documented, the occurrence of G. vaginalis in urine samples of kidney transplant recipients cannot be finally assessed. Further studies are needed to clarify its significance, particularly in immunocompromised hosts.