Chryseobacterium is a type of bacteria found widely in the environment. While many bacterial species are harmless, this genus can cause infections, particularly in susceptible individuals. Understanding these bacteria involves recognizing their basic characteristics and where they are commonly found.
What is Chryseobacterium?
Chryseobacterium is a genus of Gram-negative bacteria, meaning they do not retain the purple stain used in a common laboratory test. These rod-shaped bacteria belong to the family Flavobacteriaceae. They are known for producing a yellow pigment, which gives them their name, derived from “chryseos” (golden). This pigment can appear pale to bright yellow or orange when cultured.
These microorganisms are obligately aerobic, requiring oxygen to grow. They are also non-motile and chemoorganotrophic, obtaining energy from organic compounds. While they grow on standard laboratory media, some species show enhanced growth at temperatures up to 37°C, with clinical isolates even growing at 42°C.
Where is it Found?
Chryseobacterium species are widespread in nature, found in diverse environments like soil, freshwater, marine water, and plants. Their ability to survive in various conditions, including chlorinated water, allows them to colonize water supplies.
This environmental prevalence extends to healthcare settings, where Chryseobacterium can become an opportunistic presence. They frequently colonize wet surfaces and water systems within hospitals, including sink basins, taps, humidifiers, and medical devices. The bacteria can also form biofilms on medical equipment like catheters and prosthetic implants, serving as potential reservoirs for infection.
Clinical Significance
While generally considered to have low virulence, certain Chryseobacterium species can cause serious infections, especially in vulnerable populations. Chryseobacterium indologenes and Chryseobacterium gleum are common species isolated from clinical samples. Note that Chryseobacterium meningosepticum has been reclassified as Elizabethkingia meningoseptica, also known for causing infections.
Infections typically occur in immunocompromised individuals, neonates, the elderly, and patients with underlying health conditions like kidney disease or diabetes. Patients with indwelling medical devices or those on prolonged mechanical ventilation are also at increased risk. These bacteria can cause healthcare-associated infections, including pneumonia, bloodstream infections (bacteremia), meningitis (particularly in newborns), wound infections, urinary tract infections, cellulitis, and peritonitis.
Addressing Infections
Diagnosing Chryseobacterium infections typically involves laboratory culture and identification of the bacteria from patient samples. A significant challenge in treating these infections is the intrinsic antibiotic resistance of Chryseobacterium species. They are often resistant to many commonly used antibiotics, including carbapenems and aminoglycosides. This resistance is attributed to the production of specific enzymes, such as metallo-beta-lactamases (MBLs), which break down many beta-lactam antibiotics.
Due to this intrinsic resistance, treatment options can be limited, making susceptibility testing essential to guide therapy. Some studies indicate susceptibility to antibiotics like minocycline, doxycycline, trimethoprim-sulfamethoxazole, and certain quinolones. However, the effectiveness of these agents can vary, and high mortality rates have been observed, especially in critically ill patients. Infection control measures in healthcare settings are crucial to prevent the spread of these bacteria, emphasizing proper hygiene, management of water systems, and careful handling of medical devices to reduce the risk of patient exposure and infection.