An adult case of urinary tract infection with Kingella kingae: a case report

Introduction Kingella kingae, though part of the normal upper respiratory tract and genitourinary tract, is increasingly being recognized as an important human pathogen. During the past decade, it has emerged as a significant pathogen in the pediatric age group primarily causing bacteremia and osteoarticular infections. Adult infection usually occurs in individuals who are severely immunocompromised and most infections have taken the form of septicemia or septic arthritis. Bacteremia due to K. kingae has been reported as the immediate cause of death in patients with acquired immunodeficiency syndrome. Case presentation We present a microbiologically confirmed urinary tract infection with K. kingae in an immunocompetent 45-year-old adult woman with post-menopausal bleeding and with a history of clots. Her urine was subjected to culture and sensitivity tests. The isolated colonies were identified as K. kingae because of their typical culture characteristics such as long incubation period required for growth, beta-hemolysis, positive oxidase and negative catalase, urease indole, nitrate and citrate tests. Penicillin G disc test was positive. They were sensitive to all conventional antibiotics. Conclusion K. kingae infection is a rare occurrence in immunocompetent adults. Very few cases of microbiologically confirmed infections have been reported so far. The isolation of K. kingae from urine sample has rarely been reported. K. kingae isolates are either missed or misinterpreted by clinical microbiologists. Therefore, K. kingae deserves recognition as a pathogen.


Introduction
In 1976, Moraxella kingae was removed from the genus Moraxella and was given a new genus and species name Kingella kingae in the family Neisseriaceae [1]. Besides K. kingae, other species belonging to the genus Kingella are K. denitrificans, K. indolegenes and K. oralis. K. kingae exhibits a variable morphology (cocci, short Gramnegative coccobacilli to medium sized rods) and is considered to be a normal flora of the upper respiratory tract and genitourinary tract [2]. It has been associated with infections in children under 6 years and immunocompromised individuals [2].
Poor oral hygiene, pharyngitis and mucosal ulceration are the predisposing factors for K. kingae infections [2,3]. K. kingae bacteremia without endocarditis has also been reported in immunocompetent adults following dental manipulations [4]. K. kingae has specific tissue tropism for cardiac, valvular, joint space, and skeletal tissue and has been isolated from cases of bacteremia, endocarditis, bone and joint infection in various samples such as blood, joint fluid, and urine [5].
We report an adult patient with urinary tract infection from whom K. kingae has been isolated in urine.

Case presentation
A 45-year-old woman was admitted to the gynaecology ward of Kamineni Institute of Medical Sciences Hospital, Narketpally complaining of post-menopausal bleeding with passing of clots for the previous 18 months. She also complained of burning micturition.

Discussion
K. kingae, though a part of the normal upper respiratory tract and genitourinary tract, is increasingly being recognized as an important human pathogen. During the past decade, it has emerged as a significant pathogen in the pediatric age group primarily causing bacteremia and osteoarticular infections [7,8]. Adult infection usually occurs in individuals who are severely immunocompromised and most infections have taken the form of septicemia or septic arthritis. Bacteremia due to K. kingae has been reported as the immediate cause of death in patients with acquired immunodeficiency syndrome (AIDS) [2].
K. kingae infection is a rare occurrence in immunocompetent adults. Very few cases of microbiologically confirmed infections have been reported so far [9]. The isolation of K. kingae from urine samples has rarely been reported [6].  We isolated K. kingae from the urine of an immunocompetent 45-year-old woman with post-menopausal bleeding and with clots for the previous 18 months. In this patient, the possible source of K. kingae was the resident genital flora. Due to the regular flow of clots and tissue, the organism could have gained access through the urethra causing ascending urinary tract infection. Kingellae are nutritionally fastidious Gram-negative bacilli requiring 48 hours of incubation before reaching a colony size of 1 mm diameter. They are oxidase-positive, catalase-negative (Moraxella are positive) and positive for the Penicillin G disc test. Of all of the species, K. kingae is b-hemolytic on sheep blood agar [2]. The isolation of K. kingae is often either missed or misinterpreted. Cases of K. kingae infection are on the rise in children as well as in immunocompromised and immunocompetent adults. Therefore, K. kingae deserves recognition as a pathogen.

Consent
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.