Ewingella

Ewingella is a genus of bacteria within the family Yersiniaceae, belonging to the class Gammaproteobacteria. It is a Gram-negative bacterium that is known to be an opportunistic pathogen in humans. The genus is named after William H. Ewing, a prominent bacteriologist.

Taxonomy

Ewingella is a monotypic genus, meaning it contains only one species, Ewingella americana. This species was first described in 1983 by Grimont et al. It is classified under the order Enterobacterales, which includes other notable genera such as Escherichia, Salmonella, and Yersinia.

Morphology

Ewingella americana is a rod-shaped bacterium. It is motile due to the presence of peritrichous flagella. The cells are typically 0.5 to 1.0 micrometers in width and 1.0 to 3.0 micrometers in length. As a Gram-negative bacterium, it possesses a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides.

Physiology

Ewingella americana is a facultative anaerobe, meaning it can grow in both the presence and absence of oxygen. It is capable of fermenting various carbohydrates, producing acid and gas as metabolic byproducts. The bacterium grows optimally at temperatures between 25°C and 37°C, which corresponds to environmental and human body temperatures, respectively.

Pathogenicity

Ewingella americana is considered an opportunistic pathogen. It has been isolated from various clinical specimens, including blood, urine, and respiratory secretions. Infections are more commonly reported in immunocompromised individuals, such as those with HIV/AIDS, cancer, or diabetes mellitus.

Clinical Manifestations

Infections caused by Ewingella americana can present as:

• Bacteremia
• Urinary tract infections
• Respiratory tract infections
• Wound infections

Diagnosis

Diagnosis of Ewingella americana infection is typically made through culture of the organism from clinical specimens. Identification can be confirmed using biochemical tests and molecular methods such as 16S rRNA sequencing.

Treatment

Ewingella americana is generally susceptible to a range of antibiotics, including aminoglycosides, fluoroquinolones, and third-generation cephalosporins. However, antibiotic susceptibility testing is recommended to guide appropriate therapy, as resistance patterns can vary.

Ecology

Ewingella americana is found in various environments, including soil, water, and plants. It has been isolated from the surfaces of fruits and vegetables, indicating its potential role in food spoilage and as a vector for transmission to humans.

Research

Research on Ewingella americana is ongoing to better understand its pathogenic mechanisms, resistance patterns, and ecological roles. Studies are also focused on its interactions with other microorganisms and its potential use in biotechnology.

See also

• Enterobacterales
• Opportunistic infection
• Gram-negative bacteria