The involvement of Penicillium in microbial disease is the production of β-Lactam antibiotics called penicillin. Originally, P.notatum was used to make penicillin however; there are now other species like P.chrysogenum that manufacture penicillin in vast amount. These drugs are bactericidal because they tackle disease by binding to Penicillin-binding Proteins (PBPs) such as transpeptidase that are responsible for peptidoglycan crosslinkages. This enzyme-substrate complex inhibits the bacterial cell wall, losing its function but causes less damage to the host; this is known as selective toxicity (Willey, 2008:p.837). Phenoxymethylpenicillin (Penicillin V), is effective using this mechanism against gram-positive bacteria like Streptococcus pyogenes; a bacterium that causes skin infections. However, Phenoxymethylpenicillin is not very effective against gram-negative bacteria because they have a protective outermembrane and contain β-Lactamase enzyme that inactivates penicillin by hydrolysing a bond in β-Lactam ring. This emphasises the contribution of Penicillium to treatment of disease because its species are used to manufacture penicillin which are effective against diseases caused by gram-positive bacteria.
Other penicillins are effective against gram-positive and gram-negative bacteria. For instance, Ampicillin is less susceptible to inactivation by gram-negative bacteria and inhibits transpeptidase competitively because this semi-synthetic drug is a modified version of the natural penicillin by an addition of an amino group. This emphasises the involvement of Penicillium in the cure of disease because the antimicrobial activity can vary with individual penicillins. Some are narrow-spectrum drugs that kill specific bacteria, others are broad-spectrum that effect different bacteria.
The involvement of Pseudomonas in disease is causing them by three stages: attaching to bacteria, invading it and causing infections. The origins of Pseudomonas’ invasive infections are mainly due to its species; P.aeruginosa. P.aeruginosa is a nosocomial, antibiotic-resistant pathogen. People with Pseudomonas infections typically have low immune systems such as cystic fibrosis where Pseudomonas produces ‘slime’ in the lungs causing pneumonia (Singleton, 1995:p.286). Another infection caused by P.aeruginosa is ‘Hot Tub Rash’ the common name given to skin infection called dermatitis. It spreads via contaminated water which indicates how this pathogen can tolerate water environments and cause infection (CDC, 2010). This illustrates Pseudomonas’ contribution to disease because P.aeruginosa causes many pathogenic infections due to its cellular characteristics and ability to form biofilms which protects it from environmental factors.
Other Pseudomonas species are involved in the treatment of human microbial disease. For instance, P. flourescens extracts are used to produce an antibiotic called Mupirocin. Mupirocin is effective against gram-positive bacteria like staphylococci to treat skin infections topically. For instance, impetigo that commonly affects children who have other skin problems because it is contagious (Lancini,1995:p.178). Studies on Mupirocin have shown that it inhibits isoleucy-tRNA synthetase enzyme which can affect protein synthesis in the bacterium (Capobianco, 1989). This indicates how Pseudomonas is able to produce antibiotics against other bacteria despite itself can cause bacterial diseases.
Penicillin can cause adverse side effects such as allergies where the body produces antibodies that suspect penicillin as an antigen rather than a cure. The most severe allergic reaction is anaphylaxis where bronchi are narrowed causing breathing difficulties (Singleton, 1995:p.297). Other Penicillium spp. like P.marneffei causes disseminated infection called penicilliosis in normal immune individuals. These individuals commonly have their skin, lungs and gut infected where symptoms like lesions can be mistaken for histoplasmosis that occurs in AIDs patients. In other words, the symptoms of both infections ‘mimic’ each other (University of Adelaide, 2010). This emphasises the downside of Penicillium where penicillin causes side effects and cause disease. However, P.marneffei is the only dimorphic species in the Penicillium genus.
Ultimately, microbes have major importance in disease, some can be pathogenic, and others can be beneficial to produce antimicrobial drugs. Both Penicillium and Pseudomonas are involved in the cause and cure of human microbial disease. However, Penicillium predominantly contributes to treatment of bacterial diseases but depends on its side chain that determines its effectiveness. Pseudomonas predominately causes infections due to its cellular characteristics that enable it to become antibiotic-resistant. In fact, Ticarcillin, semisynthetic penicillin is effective against P.aureginosa. Today, researchers aim to develop new semi-synthetic drugs to treat disease as the number of antibiotic-resistant microbes increase to help treat human microbial disease.
Capobianco,J., Doran,C., Goldman,R. (1989) ‘Antimicrobial Agents and Chemotheraphy: Mechanism of mupirocin transport into sensitive and resistant bacteria’ American Society For Microbiology: 33 (2): 156-163. Available online: http://aac.asm.org/cgi/content/abstract/33/2/156
Centre for Disease Control and Prevention (2010) ‘Hot Tub Rash’ Pseudomonas Dermatitis/ Folliculitis’ Available online: http://www.cdc.gov/healthyswimming/derm.htm
Lancini, G., Parenti, F., Gualberto Gallo, G., (1995) ‘Antibiotics: A Multidisciplinary Approach’. New York: Plenum Press. pp.178
Singleton, P. (1999) ‘Bacteria in Biology, Biotechnology and Medicine’ 5th ed. England: John Wiley & Sons Ltd pp.286, 297
University of Adelaide (2010) ‘Mycology online: Penicilliosis marneffei’ Available online: http://www.mycology.adelaide.edu.au/Mycoses/Opportunistic/Penicilliosis_marneffei/
Willey,J., Sherwood, L., Woolverton,C. (2008) ‘Prescott, Harley, and Klein’s Microbiology’ 7th ed. New York: McGraw-Hill pp.60, 556,631,837.