Nocardia is a group of bacteria that is normally found in your mouth. If you have a healthy immune system, then nocardia species will cause you no harm, but if your immunity is weakened due to age, infection or poor nutrition, then some species can become pathogenic. The most common nocardial disease is pneumonia, which is treated by antibacterial drugs that inhibit the bacteria's ability to produce folic acid and reproduce. Folic acid can also be used by the host to reduce the side effects of the antibiotic therapy.
About Nocardia
Nocardia is a genus of gram-positive, rod-shaped bacteria. Nocardia includes about 85 species, some of which act more like fungi because they grow long, branching filaments. Nocardia species are found virtually everywhere where there is organic-rich soil. Further, some nocardia species are found in healthy gums and periodontal tissue in your mouth. Most species of nocardia display low virulence, which means they only cause opportunistic infections in those with underdeveloped or weak immunity, such as small children, the elderly and the immune compromised. The most dangerous species are N. asteroids, N. brasiliensis and N. caviae. Most nocardia infections are acquired by inhaling the bacteria or invasion through an open cut.
Nocardiosis
Nocardia asteroides is the species that most commonly infects people, especially those with HIV infections. The most common nocardial disease is a slowly progressive pneumonia, which causes coughing fits, shortness of breath and fever. Untreated, nocardiosis can lead to inflammation of the heart and brain. Nocardiosis is usually successfully treated with a combination of antibiotics.
TMP-SMX
Trimethoprim and sulfamethoxazole, or TMP-SMX, are sulfonamide-type antibiotics used in combination to fight a variety of bacterial infections, including nocardiosis. It is marketed under the names Septra and Bactrim. Trimethoprim and sulfamethoxazole have greater effects when given together rather than separately because they inhibit successive steps in the folic acid synthesis pathway within bacteria. Folic acid is needed for the synthesis of DNA, and because bacteria are unable to take up folic acid from your body, they are dependent on their own production of it. TMP-SMX inhibits an enzyme within bacteria and prevents them from making folic acid, which stops them from replicating. TMP-SMX is not without side effects though.
Side Effects and Folic Acid
TMP-SMX is commonly associate with mild allergic reactions and sometimes associated with serious adverse effects, including Stevens-Johnson syndrome, severe liver damage and kidney impairment. Interestingly, folic acid supplementation was found to be a cheap and effective method of reducing the adverse effects of TMP-SMX, according to "Vitamins: Fundamental Aspects in Nutrition and Health." It seems that TMP-SMX also has inhibitory effects on folic acid production and absorption in people.
References
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
- "Professional Guide to Diseases: Ninth Edition"; Springhouse Publishing; 2009
- "Compendium of Pharmaceuticals and Specialties"; Canadian Pharmacists Association; 2010
- "Vitamins: Fundamental Aspects in Nutrition and Health"; G. Combs; 2008
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