Monobactams
Monobactams are synthetic antibiotics that have a single lactam ring and re-
sist penicilinase. Monobactams destroy only areobic gram-negative bacteria
such as E. coli.
Cephalosporins
Cephalosporins are resistant to penicillinases and destroy gram-negative bac-
teria. The disadvantage of cephalosporins is they can be made ineffective by
b-lactamases.
Carbapenems
Carbapenems have a broad spectrum of activity that prevents the breakdown of
the antibiotic by the kidneys. These antibiotics inhibit the synthesis of cell walls.
An example is Primax (trade name). Primax has proved effective against 98 per-
cent of all organisms that were isolated from patients in hospitals.
Bacitracin
Bacitracin is used against staphylococci and streptococci and other gram-positive
bacteria and is used as a topical antibiotic for superficial infections.
Vancomycin
Vancomycin has a very narrow spectrum of activity and is the most effective
antibiotic against staphylococci that produce penicillinase. Vancomycin is used
in the treatment of endocarditis. However, vancomycin can be toxic to humans.
Isoniazid
Isoniazid (INH) inhibits mycolic acid, which is needed for synthesizing the cell
wall of Mycobacteria tuberculosis. Isoniazid is only effective fighting mycobac-
teria tuberculosis.
Ethambutol
Ethambutol is similar to isoniazid and is used as a secondary treatment to avoid
Mycobacteria tuberculosisbecoming resistant to isoniazid.
CHAPTER 16 Antimicrobial Drugs^239