Kingella kingae

Kingella kingae is a Gram-negative, rod-shaped bacterium that thrives in the human body, particularly in warm-blooded hosts, making it a mesophile. It is classified as a chemoheterotroph, obtaining its energy through the consumption of organic compounds, and is a facultative anaerobe, allowing it to survive in both aerobic and anaerobic environments. This microbe commonly colonizes the upper respiratory tract of healthy individuals, where it exists as part of the normal flora. Besides the nasopharynx, K. kingae has been isolated from various body sites, including the throat, oral cavity, and even in some instances, sterile body fluids when associated with infections. Its prevalence in the nasopharynx underscores its role in both commensalism and opportunistic pathogenicity. Kingella kingae is notably recognized for its association with osteoarticular infections, particularly in young children, where it can cause conditions such as septic arthritis and osteomyelitis. The pathogen is often implicated following trauma or in immunocompromised states, highlighting its opportunistic nature. The bacterium’s virulence factors include its ability to adhere to host tissues, evade immune responses, and form biofilms, enhancing its persistence in host environments. In laboratory settings, K. kingae demonstrates unique biochemical characteristics, such as the production of beta-lactamase enzymes, which can confer resistance to certain antibiotics. Its significance in clinical microbiology has increased due to the rising recognition of infections it can cause, particularly in children, and its challenge in diagnosis, as it often requires specific culture conditions for optimal growth. This microbe remains an area of interest for researchers studying infectious diseases, particularly in understanding its pathogenic mechanisms and developing potential treatments.