Prevention and control of bacterial disease

Although bacteria were first seen and depicted with remarkable accuracy by Anthony van Leeuwenhoek in the late 17-th century, they were not generally recognized as a cause of disease until 100 years ago. Recognition of microbes as disease agents led directly and swiftly to control measures. Among them were: physicians, surgeons, nurses, and hospitals. Some organisms make chemicals that prevent the growth of bacteria. These chemicals are called antibiotics. The first antibiotics where discovered in 1929 by Alexander Fleming. They are used to kill pathogenic bacteria. Bacteria, produce most antibiotics; fungi, especially the actinomycetes, form few. These antibacterial agents act by interfering with metabolic reactions essential to the bacteria but not to the cells. Penicillin, for example, inhibits bacterial growth by interfering with the cross-linking of the peptide chains in the bacterial cell walls.

The battlefields of World War II were the proving grounds for new antimicrobial drugs, such as sulfa and penicillin. Penicillin is a well-known antibiotic that cures strep throat and other diseases by killing the bacteria, which cause it. Penicillin was the first discovered antibiotic – by definition, a chemical that is produced by a living organism and is capable of inhibiting the growth of microorganisms.

Immunization, which involves the stimulation of the body’s natural defenses against a disease-causing agent, is also responsible for the prevention of many bacterial diseases, including diphtheria, whooping cough and tetanus.

Bacteria	Examples	Form	Motility	Mode of nutrition	Distribu-tion	Ecologi-cal role	Diseases
Eubac-teria	Escherichia Coli, Strep-tococcus, Mycobacte-rium tuberculosis	Rod-shaped (Bacillus), spherical (coc cus), spirillum (curves), vib-rio (one curve)	Gliding, flagella	Chemo-autotrophs, Photosyn-thetic auto-trophs, heterotrophs	Soil, water, parasites	Decompo-sers, sym-bionts, pathogens	Lockjaw, diphtheria, tuberculosis
Myxo-bacteria	Myxococ-cus, Cyto-phage, Chondro-myces	Rod-shaped, flexible, in slime	Gliding	Heterotrophs	Soil, some aquatic bacteria	Decompo-sers of complex polysacharides	None
Spiroche-tes	Spirocheta, Treponema, Leptospira	Extremely long, helical	Twisting (axial filament)	Heterotrophs	Aquatic (polluted water), parasitres	Symbionts in mollusk, pathogens, decompo-sers	Syphilis, infectious jaundice, relapsing fever
Ric-kettsiae	Rickettsia	Small, 0,3 – 0,5 micrometers	None	Heterotrophs (parasites)	Intracellular parasites	Pathogens	Typhus, spotted fever
Myco-plasma	PPLO	Smallest free-living cells, no cell walls	None	Heterotrophs	Intracellular parasites, soil	Pathogens	Mycoplasm pneumonia

Table 3.1