Direct instillation of Lactobacillus plantarum into rat bladder inhibits urinary tract infection (UTI) and protects the integrity of urinary organs

Abstract

Urinary tract infection (UTI) remains one of the commonest clinical problems presenting to medical practitioners. UTIs are frequently treated with antibiotics, which has exacerbated the emergence of resistant strains among uropathogens. Consequently, there is increasing interest in the development of safe alternatives to antibiotics. The use of probiotics has been advocated as a plausible alternative to antibiotics, but questions remain as to their mode of application. This study was therefore conducted to evaluate the ability of Lactobacillus (L.) plantarum, inoculated intraurethrally into rats, to inhibit the establishment of UTI by selected multidrug-resistant uropathogens [E. coli and Klebsiella (K.) pneumonia]. Nine-week old, male, albino rats, were either infected and then treated with L. plantarum or inoculated with L. plantarum before infection. UTI was monitored by determination of bacterial counts from the rats’ urine over a period of 14 days, direct culture from- and histological examination of sections of bladder and kidneys of the animals after sacrifice. In untreated rats, both E. coli and K. pneumonia established UTI in the rats within 4 days, with bacterial counts, in urine, increasing from 10⁴ CFU/ml to about 10⁶ CFU/ml, over the course of 14 days. The infections were accompanied by inflammatory changes in both the bladder and kidneys and bacteria were recovered from sections of the kidneys after sacrifice. In animals infected and then treated with L. plantarum, the numbers of the pathogens in urine decreased significantly (p < 0.005) to less than 10³ CFU/ml, while pre-colonization of the bladder with L. plantarum before infection resulted in complete inhibition of the uropathogens. No pathological changes were observed in the urinary organs of the treated rats. These results therefore show that L. plantarum can colonize the bladder safely and serve as an effective means of control of UTI.

Keywords: UTI, Lactobacillus plantarum, uropathogens, bladder, probiotics, E. coli.