Academic literature on the topic 'Sulphonamide drugs'

Nocardia species—Nocardia asteroides, N. brasiliensis, and N. otidiscaviarum—are Gram-positive, filamentous, partially acid-fast bacteria. They are occasionally detectable in environmental sources such as soil, but they rarely cause infections in humans, although they can give rise to a variety of different diseases. In healthy individuals, most commonly in the tropics, they can present with cutaneous abscesses or subcutaneous infections (actinomycetoma) in which the organisms are present as clusters of filaments or grains. In immunocompromised patients they cause a disseminated or localized deep infection, with particular sites affected being the lungs or brain. Diagnosis of Nocardia infection depends on culture, although histopathology is very useful in Nocardia actinomycetomasiii. Antibiotic treatment is typically with a sulphonamide (often as co-trimoxazole for lung infections), but combinations of drugs are usually given because the responsiveness of Nocardia species is very variable.

Broad-spectrum antibacterial agents kill most bacteria including gram-positive rods and cocci, gram-negative rods and cocci, and often anaerobes too. Narrow-spectrum agents kill a narrow range of microbes, e.g. benzylpenicillin is mainly active against gram-positive cocci. By and large a narrow-spectrum antimicrobial is less likely to disrupt a patient’s normal flora than a broad-spectrum agent. Hence, if the likely organism is causing an infection it is best to give a narrow-spectrum antimicrobial to treat that specific organism. If a patient presents ‘septic’ and the source of infection is unknown, relevant cultures should be taken followed by broad-spectrum antimicrobial cover. This can later be modified either when the source of infection is found or as a result of microbiology culture results. ● Agents mostly active against gram-positive bacteria include: ■ Penicillin (Also active against Neisseria spp.). ■ Fusidic acid. ■ Macrolides (Also active against Legionella, Campylobacter, Bordetella spp.). ■ Clindamycin. ■ Glycopeptides. ■ Oxazolidinones. ■ Streptogramins. ● Agents mainly active against gram-negative bacteria include: ■ Polymyxin. ■ Trimethoprim. ■ Aminoglycosides (also active against staphylococci and show synergy when combined with beta-lactams against/glycopeptides against streptococci). ■ Monobactams. ■ Temocillin. ● Broad-spectrum antimicrobials include: ■ Beta-lactam plus beta-lactamase inhibitor combinations. ■ Cephalosporins. ■ Carbapenems. ■ Chloramphenicol, Tetracyclines/Glycyclines. A bactericidal agent is a compound that actively kills multiplying bacteria. A bacteriostatic compound inhibits the growth of bacteria. Whether or not an antimicrobial is bactericidal or bacteriostatic depends on a variety of things, including the type of agent, its concentration, and the organism it is being used to treat. It is especially important to try and use a bactericidal agent if the patient’s immune system is impaired or the infection is at a site where it is difficult for the immune system to access, e.g. the heart valves in bacterial endocarditis, the meninges in meningitis. Examples of each are given here: ● Bactericidal agents include beta-lactams, glycopeptides, fluoroquinolones, and aminoglycosides. ● Bacteriostatic agents include macrolides, clindamycin, tetracyclines, trimethoprim, and sulphonamides. The therapeutic index of a drug is the ration of the concentration of drug likely to be toxic to the patient divided by the concentration of drug likely to be clinically effective.