A pathogen is a microorganism that can cause a disease or has the ability to cause a disease. An opportunistic pathogen is not different from any other kind of pathogen. The only difference is that, an opportunistic pathogen can cause a disease in a person who has a lower immunity or an impaired immune system, but not in someone who is healthy. In other words, an opportunistic pathogen, which can otherwise not harm a person, finds an opportunity to establish himself in the affected person’s body and cause some kind of disease (Pirofski, 2012).
An example of an opportunistic pathogen is the Stenotrophomonas maltophilia, which is a globally found multi-drug resistant organism that most commonly affects the respiratory system of humans. It has the ability to cause various serious infections. Other than respiratory system, it can also affect the skin, bones, meninges, heart, liver, and the urinary tract. It is not highly virulent, but it is considered to be an important hospital-acquired infection. The incidence of S. maltophilia hospital-acquired infections is reported to be increasing, particularly in those who have an impaired immune system. The infection can occur in both children and adults. To reduce the rising incidence of S. maltophilia in hospitals and clinics, educating the healthcare professionals in of prime necessity (Brooke, 2012).
Mitochondrial inheritance is also known as maternal inheritance. It means acquisition of characteristics from a parent to offspring. It is a pattern of inheritance through the female line i.e., from mother to son or from mother to daughter. The cells of a body contain genes. Genes are located on chromosomes, which is made of a chemical called DNA. Another place where DNA is found is the mitochondria, which means mitochondria too contain DNA. Mitochondria are the one responsible for making most of the body’s source of energy, which is a chemical called ATP. A number of biochemical reactions occurring in the mitochondria in an ordered sequence are responsible for ATP production. A change in any of the mitochondrial genes leads to reduction in ATP supply, which ultimately results in problems with the body’s functions.
All of the mitochondria, and therefore, the DNA present on the mitochondria come from the mitochondria present in the original egg cell at the time of that person’s conception. If there is a change (mutation) in any of the mitochondrial genes that makes it faulty, it can be passed on by the mother to her offspring. This pattern of inheritance is therefore also called as Maternal inheritance (Mitochondrial Inheritance).
Common types of cancer
Some common types of cancer diagnosed very commonly in the US are cancers of the prostate, bladder, breast, colon and rectum, endometrium, lungs, skin, pancreas, renal, leukemia and thyroid. To qualify as a common cancer, the estimated annual incidence has to be above 40000 cases (year 2012). The most common of these cancers was the prostate cancer, which had more than 240,000 new cases in 2012 in the US, whereas the cancer with the lowest incidence was pancreatic cancer with 43,920 new cases for the same year (National Cancer Institute). The table below gives the estimated new cases and deaths due to every common type of cancer in the US (National Cancer Institute)
- Pirofski, L., Casadevall, A. (2012) Q&A: What is a Pathogen? A question that begs the point. BMC Biology. 10, 6.
- Brooke J (2012) Stenotrophomonas maltophilia: an Emerging Global Opportunistic Pathogen. Clinical Microbiology Reviews, 25, 1-40. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255966/pdf/zcm2.pdf
- Mitochondrial inheritance – Complex patterns of Inheritance – 2. (2007) The Australiasian Genetics Resource Book. Available at: http://www.genetics.edu.au/Information/Genetics-Fact-Sheets/Mitochondial-Inheritance-Complex-Patterns-of-Inheritance-2-FS12