Pharmaceutical Importance of the Major Categories Of MicroorganismsPharmaceutical Relevance

Type of organismContamination orspoilage of raw materialsand medicines

PathogensResistance toantibiotics andbiocides

Resistance tosterilizing agentsand processes

Used in themanufacture oftherapeutic agents

Implications

Viruses++Because of their lack of intrinsic metabolism viruses are not susceptible to antibiotics and the number of effective synthetic antiviral drugs is limited so viral infections are among the most serious and difficult to cure. They have no synthetic capabilities that can be exploited in medicine manufacture.

Prions+++Prions are hard to destroy by heat, radiation or toxic chemicals, they have their extreme resistance to lethal agents so for this reason, they can easily withstand sterilizing conditions so they cause product spoilage, and they have no synthetic capabilities that can be exploited in medicine manufacture.

Bacteria

Gram-negative++++Many of the medically and pharmaceutically important bacteria are pathogens as a result of their ability to resist the activity of antibiotics and biocides. The role of the lipopolysaccharides (LPS) as a permeability barrier in Gram-negative bacteria reduced biocide efficacy. The ability of bacteria to grow on diverse substrates ensures that their potential as agents of spoilage in manufactured medicines and raw materials is well recognized.

Gram-positive++++ (spores)+The ability to survive not only in dry conditions but in other adverse environments (heat, radiation, toxic chemicals) is well exemplied by bacterial spores. The ability of bacteria to grow on diverse substrates ensures that their potential as agents of spoilage in manufactured medicines and raw materials is well recognized. Many of the medically and pharmaceutically important bacteria are pathogens as a result of their ability to resist the activity of antibiotics and biocides.

Mycobacteria++Vegetativebacteriasuch as mycobacteria have an intrinsicresistancemechanism to biocides referred to as "permeability barrier". The permeability barrier limits the amount of a biocide that enters the cell, thus decreasing the effective biocide concentration. The presence of mycoylacylarabinogalactan layer accounts for the impermeability to manyantimicrobials.

Streptomycetes++A variety of bacteria are exploited commercially in the manufacture of other medicines. The majority of the other categories of clinically important antibiotics are produced by streptomycetes.

Chlamydia+Chloramphenicol has an especially broad spectrum of activity against Chlamydia.

Rickettsia+Rickettsia is not resistant to antibiotics. Doxycycline is the drug of choice, it is preferred over other tetracyclines for treatment of rickettsial infections. Chloramphenicol may be used as an alternative.

Mycoplasma+Chloramphenicol antibiotic has an especially broad spectrum of activity against mycoplasma.

Fungi

Yeasts++++Yeast can be genetically engineered to produce artemisinic acid, a precursor to the best malaria treatments. Yeast are involved in the industrial processing of more than 10 of the 20 most profitable products used in human medicine. Two anti-cholesterol statins, the antibiotic penicillin and the immunosuppressant cyclosporin A are among the top 10.

Moulds++++Like bacteria, fungi are able to form spores that survive drying, so they too arise commonly as contaminants of manufactured medicines. However, the degree of resistance presented by the spores is usually less than that exhibited by bacteria, and so fungi do not represent a sterilization problem. Fungi do not generally create a signicant infection hazard either. Molds are used in the manufacture of therapeutic agents, Alexander Fleming's accidental discovery of the antibioticpenicillininvolved aPenicilliummold calledPenicillium notatum.

Protozoa+Protozoa are of signicance largely owing to the pathogenic potential of a few species. Because protozoa do not possess cell walls they do not survive drying well (unless in the form of cysts), so they are not a problem in the manufacturing environment and even the encysted forms do not display resistance to sterilizing processes. It should be noted that protozoal infections are not currently a major problem to human health in temperate climates, although they are more troublesome in veterinary medicine and in the tropics.