A diagnostically challenging case of pyelonephritis caused by Lactobacillus

Extracellular polysaccharides produced by Lactobacillus have been shown to stimulate the immune system, suppress reactivity to allergens, and protect from infections; these properties underlie the use of Lactobacillus in probiotic formulations and in the prevention and treatment of urinary tract infections. However, Lactobacillus can be independently isolated at high numbers from sites of infection and has been rarely considered as the causative agent of infections in immunocompromised individuals. We herein report the case of a 46-year-old female patient who developed pyelonephritis due to Lactobacillus following total thyroidectomy for papillary thyroid cancer. The patient also had to fast due to postoperative vocal cord paralysis and received steroid treatment. As illustrated in the clinical course of our patient, Lactobacillus can be overlooked as a contaminant in culture samples and should be suspected as the etiology of infection especially in patients with weakened immune responses. We suggest that the detection of Lactobacillus in culture these patients might be an indication to initiate appropriate antibiotic treatment without delay.