- Gram-negative small rods (respiratory infections: pneumonia, whooping cough)
Hemophilus influenzae
Bordetella pertussis - Gram-positive bacilli (food poisoning)
Clostridium botulinum
Clostridium tetani - Pyogenic cocci (various localized infections)
Staphylococci(wound infections)
Streptococci(pharyngitis—“sore throat”)
Pneumococci(pneumonia)
Neisseria meningitides(meningitis)
Neisseria gonorrheae(gonorrhea) - Gram-positive rods
Corynebacterium diphtheriae(diphtheria) - Mycobacteria (slow chronic infections)
Mycobacterium tuberculosis(tuberculosis)
Mycobacterium leprae(leprosy) - Spirochetes (chronic diseases, venereal disease)
Treponema pallidum(syphilis) - Rickettsia (fever and rash transmitted by arthropods such as lice)
Rickettsia prowazekii (typhus)
Rickettsia rickettsii(Rocky Mountain spotted fever) - Chlamydia
Chlamydia trachomatis(venereal infection)
This classification is based on various criteria, including shape of the bacterium (rod,
cocci) and the ability of the bacteria to be stained with a crystal violet-iodine complex
in the presence of alcohol (Gram staining). This classification system also contains
rickettsiae and chlamydiae; both of these tend to be at the interface with viruses in that
they are intracellular bacteria.
Currently there is a wide variety of agents available for the treatment of bacterial
infections. A broad spectrum agent works against many types of bacteria. A bacterio-
staticagent does not kill bacteria but does inhibit their reproductive growth; a bacteri-
cidalagent actually kills bacteria. The term antibioticis frequently used interchangeably
for antibacterial. The word antibiotic, proposed by Waksman in 1942, refers to a substance
that is able to inhibit the growth or even destroy microorganisms; the term is derived from
Vuillemin’s concept of antibiosis(which literally means “against life”). The designation
of antibiotic can thus be applied not only to antibacterials but also to other antimicro-
bials such as antifungal agents. To avoid confusion, this book will use the more precise
term of antibacterial agent.
The rational design of antibacterial agents depends upon the exploitation of a mole-
cular structural feature found in bacteria but not found in humans. There are a number
of such targets within bacteria, including the bacterial cell wall, bacterial cell mem-
brane, bacterial protein synthesis, and bacterial nucleic acid synthesis. Various types of
antibacterial agents can be categorized into four druggable target groupings according
to the general structure of bacteria as shown in figure 9.3:
560 MEDICINAL CHEMISTRY