Microbe of the month: Corynebacterium

Classification: Bacteria

Cultured from / Found in: HVAC Coils, Filters, Grilles and Diffusers

Associated Health Risks: Fever and Swelling of Nose and Throat, Pseudomembrane Diphtheria, Skin Lesions/Infections, Paralysis, Heart Failure


Corynebacteria (from the Greek words koryne, meaning club, and bacterion, meaning little rod) are gram-positive, catalase-positive, aerobic or facultatively anaerobic, generally nonmotile rods. The genus contains the species Corynebacterium diphtheriae and the nondiphtherial corynebacteria, collectively referred to as diphtheroids. Nondiphtherial corynebacteria, originally thought to be mainly contaminants, have increasingly over the past 2 decades been recognised as pathogenic, especially in immunocompromised hosts [1].

Diphtheria is a serious infection caused by strains of bacteria called Corynebacterium diphtheriae that make toxin. It can lead to difficulty breathing, heart rhythm problems, and even death [2]

Children under 5 and adults over 60 years old are particularly at risk for getting diphtheria [3]. Children and adults that don't have up-to-date immunisations are also at risk. Infections are rare in properly immunised people, although people that have been immunised may still be carriers of the bacteria.

Corynebacterium diphtheriae is the pathogenic bacterium that causes diphtheria. It produces an extremely potent exotoxin known as diphtheria toxin which alters protein function in an infected individual. The toxin can be distributed by the circulatory system to other organs and may cause paralysis and congestive heart failure.

The most severe form of diphtheria affects the throat and tonsils. The first symptoms are usually a sore throat, loss of appetite and a mild fever. Within 2-3 days, a greyish-white membrane forms over the throat and tonsils that can make it hard to swallow and breathe. The infection can also cause the neck to swell. [4]

There are two types of the disease. With respiratory diphtheria infected individuals may have a sore throat with low-grade fever and an adherent pseudomembrane of the tonsils, pharynx, or nose. Neck swelling is usually present in severe disease. Cutaneous diphtheria causes infected skin lesions which lack a characteristic appearance.

[1] https://emedicine.medscape.com/article/215100-overview [2] https://www.cdc.gov/diphtheria/ [3]https://kidshealth.org/en/parents/diphtheria.html https://www.environmental-expert.com [4]https://www.health.nsw.gov.au

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