Aeromonas - Everything You Should Know About!

Introduction:

Bacteria have a million species; one in the wide-ranging group is a species called Aeromonas. They are rod-shaped bacteria widely present in the marine environment, soil, and food items. Aeromonas species are responsible for various diseases affecting the warm-blooded (that can maintain and regulate the body temperature) and cold-blooded (cannot tolerate extreme temperatures) organisms. They are primarily responsible for human gastrointestinal infections but can affect other human systems and animals.

How Is Aeromonas Species Classified?

Aeromonas species are classified based on the type of living being it affects, as;

• Motile-species affecting humans, which includes eight Aeromonas species.

• Non-motile species, which specifically affect the fishes.

How Is Aeromonas Transmitted?

A person can get Aeromonas infection mainly through oral or fecal transmission. The factors that play a critical role in the transmission of the Aeromonas species include;

• Consuming contaminated food and water.

• Using contaminated water for day-to-day activities.

• Inadequate hand hygiene.

• Consuming contaminated foods, including dairy products, meat, fish, etc.

• It can be transmitted from the contaminated soil during sports and spreads through the water when swimming or playing in contaminated water.

• It can also spread by human contact through blood, infected wounds, feces, etc.

Where Are Aeromonas Species Present?

Aeromonas species are spread widely in and around the living necessities; their main harboring occurs in the following;

In Water: Aeromonas is present in chlorinated water, bottled water, groundwater, contaminated sewage water, seawater, etc.

In Food Products: Foods of animal origin can transmit Aeromonas from animals to humans. It includes fish, shrimp, quail eggs, meat, vegetables, dairy, etc.

In Humans: Aeromonas is commonly seen in the human gastrointestinal tract and feces.

In Animals: Also, animal feces appears to be another major source of Aeromonas.

What Are the Properties of Aeromonas?

Aeromonas bacteria possess the following properties;

• They are gram-negative as Aeromonas does not take up the crystal violet stain during gram staining (a procedure that uses stains to group the bacteria as gram-positive and gram-negative).

• Aeromonas species do not form spores (a reproductive cell that causes the multiplication of the bacteria by themselves).

• They are halophilic (salt-loving) and are predominantly present in the marine environment and salt lakes.

• Acids can readily decolorize even after chemical staining (non-acid fast).

• Aeromonas species belong to the facultative anaerobes group that can survive with or without oxygen.

• Survive in marine environments by forming biofilms (a large group of bacteria enclosed in a matrix).

• Aeromonas species have inherent (permanent or inbuilt) resistance to many antibiotics, including Penicillins.

• Though Aeromonas species can survive any temperature range, Aeromonas infections are frequent during warmer months.

What Are the Diseases Caused by Aeromonas?

Aeromonas species is responsible for various diseases affecting humans and animals, including;

• Short-term (acute) and long-term (chronic) diarrhea in children and elderly and travelers’ diarrhea.

• They cause infections in the wound injuries caused by trauma and septicemia (a life-threatening bloodstream infection). In addition, Aeromonas has been detected in infected surgical wounds as well.

• They are also responsible for certain systemic infections such as urinary tract infections, peritonitis (inflammation of the membrane lining the stomach), meningitis (inflammation of the membrane lining the brain and spinal cord), endocarditis (a condition in which the heart's inner lining gets infected), etc.

What Is the Incubation Period for Aeromonas Infection?

• The incubation period for Aeromonas species infection in the gastrointestinal tract is one to two days. In the case of cellulitis, it ranges from eight hours to two days. For bacteremia (presence and circulation of the bacteria in the blood), incubation can happen anywhere between one day to 38 days.

What Are the Symptoms of an Aeromonas Infection?

Initial symptoms of Aeromonas usually are fever, chills, increased stool frequency (diarrhea), etc., which are the very commonly occurring symptoms in many medical conditions. Hence, Aeromonas cannot be diagnosed just by looking at the symptoms. In gastrointestinal infections, diarrhea ranges from mild watery discharge to discharge of blood.

Who Is Highly Susceptible to Aeromonas Infection?

Aeromonas usually affects babies, young children, the elderly, and immunocompromised individuals.

What Are the Predisposing Factors of Aeromonas Infection?

Patients with diabetes, liver disorders, hematological disorders, kidney-related problems, etc., are highly prone to systemic infections by the Aeromonas species.

How To Control Aeromonas Infection?

Most infections caused by Aeromonas can be prevented by following proper hygiene protocols. Following are a few hygiene measures one should follow;

• Maintain hand hygiene by frequently washing, mainly before meals.

• Maintain proper sewage disposal protocols.

• Keep the household water, food, and sanitation in check.

• Proper disposal of waste products and diseased animals.

• Follow proper water treatment methods.

• Cook at proper temperatures and avoid consumption of unsanitized food.

• When a particular agent, such as food, is suspected of infection, dispose of it in sealed bags.

• Exposure to moist or dry heat can effectively inactivate the bacteria, and temperatures more than 62 degrees Celsius for a few minutes act lethally to the Aeromonas species.

How Is an Aeromonas Infection Diagnosed?

• The tests that identify Aeromonas species include culture (usually performed for feces) and biochemical tests such as polymerase chain reaction, gram staining, etc., which are reliable.

• If the patient does not respond to Aeromonas-resistant antibiotics after giving a history of consuming contaminated food or water and symptoms associated, Aeromonas infection might be the cause.

Which Are the Aeromonas-resistant Antibiotics?

Most of the strains of Aeromonas have resistance to antibiotics, including Penicillin, Amoxicillin, Ampicillin, Clindamycin, Cephalothin, Carbenicillin, Ticarcillin, etc. Studies also have shown resistance to Erythromycin in more than half of the Aeromonas infections.

How Is Aeromonas Infection Treated?

• Mild gastrointestinal symptoms such as diarrhea caused due to Aeromonas do not require any specific treatment; adequate rehydration effectively controls the associated symptoms.

• Immunocompromised individuals (individuals with weaker immune systems) need antibiotics as treatment.

• Antibiotics are required only when the gastrointestinal symptoms are severe and non-subsiding or if the infection shows systemic complications.

• Aeromonas bacteria are resistant to narrow-spectrum antibiotics like Penicillin, Ampicillin, etc. Combining Clavulanic acid with Penicillin has been shown to improve its antimicrobial activity. The commonly prescribed antibiotics for Aeromonas infection that have shown notable effects include Ciprofloxacin, Gentamicin, Amikacin, Co-trimoxazole, a certain combination of these drugs, etc.

Conclusion:

Aeromonas infection is one of the various health threats to the public. Its existence in the day-to-day necessities such as water, vegetables, and meat makes human contact unavoidable and transmits easily. However, maintaining proper hygiene and sanitation protocols can keep the public far from the risk of Aeromonas infection.