Prolonged or improper use of antibiotics for typhoid can lead to long term effects. Antibiotics place selective pressure that can cause resistant strains of Salmonella to emerge and spread. As these resistant bacteria reproduce and share their resistance genes with others, diseases may persist longer with worse symptoms. This can eventually lead to incurable infections if resistance grows. Careful and appropriate antibiotic use under medical guidance can help reduce resistance development. Vaccines may also slow bacterial evolution by strengthening the body's natural immunity.

1. 120 Journal Report Summary
Duenas, Kevin
Ocampo, Kristine Angeline
Explain the long term effects of antibiotic treatment for typhoid patient.
Additional Information: Antibiotics are associated with several side effects such as irritable bowels, which is considered the most common one.
Among the most serious complications of using antibiotics is the loss of kidney function (nephrotoxicity) and loss of balance (ototoxicity).
The Salmonella sp. is a gram negative, motile, facultative intracellular bacillus, which causes bacterial
gastroenteritis, salmonellosis and Typhoid fever which causes millions of deaths annually. Over the years, several
antibiotics such as ampicillin, chlorampenicol and trimethoprimsulfamethoxazole among others were used to treat
these diseases. However, a gradual yet progressive rise in the multidrug resistant strains (MDR) of Salmonella sp. is
catching the eye of microbiologists and general public alike. MDR strains are organisms which are said to have
developed certain mechanisms against antibiotics, making them useless and eventually leaving the host’s body
absent of exogenous protection against these microscopic invaders.
Through the years, several studies have noted the decreasing sensitivity of pathogenic microorganisms to
the mainstream antibiotics, ultimately giving rise to what is currently referred to as the war between potent
antibiotics and multiple drug resistant microorganisms such as MDR Salmonella and the more commonly
recognized MRSA. One of the myriad of drugs against the increasingly resistant Salmonella strains is the utilization
of a natural antimicrobial substance of a mammalian body, the nitric oxide (NO). Nitric oxide, a gaseous, inorganic
free radical and produced in biological system is said to have a host defense function against Salmonella. It is
produced through the conversion of L-arginine to L-citrulline by nitric oxide synthase in leukocytes, hepatocytes
vascular smooth muscle, and endothelial cells. NO also acts in cell to cell communication and can be toxic in high
amounts. Other synthetic drugs are ofloxacin and nitrofuratoin, which are not advisable to use unless illnesses are
confirmed to be caused by MDR organisms.
Antibiotic resistance in microorganisms is achieved through a variety of means. The use of antibiotic
induces selection pressure, which exterminates susceptible microorganims and leaves the resistant ones alive if
medication is not followed properly. Resistant microorganisms will then reproduce indefinely due to the absense
of competition. However, resistance can also be acquired by the susceptible ones through gene transfer from the
cells that already have the "resistance" gene either through conjugation or by horizontal gene transfer. These
microorganisms that received the "resistance" genes will then develop mechanisms to counteract antibiotics such
as efflux pumps and structures that produce enzymes with the ability to degrade certain drugs such as penicillin.
Since almost all pathogenic microorganisms have the capability to share genetic materials through
conjugation or horizontal gene transfer, prolonged exposure to Typhoid fever caused by resistant Salmonella may
induce resistance to other microorganisms in the body which will in turn, cause diseases that persist for a relatively
long time with more intense symptoms. In the long run, this will give rise to incurable diseases that will lead to
inevitable death. Because of this alarming antibiotic resistant phenotype of microorganisms, it is suggested to take
only the antibiotics for certain diseases as prescribed by doctors and refrain from using potent antibiotics to non-
resistant microorganisms as it will greatly increase selective pressure and hasten the process. The use of vaccines
to increase body immunity is also encouraged to slow the microevolution of microorganisms down.
References: Arora, D., Singh, R., Kaur, M. & Ahi, R. (2010). A changing pattern in antimicrobial susceptibility of Salmonella enterica serotype isolated In North India. African Journal of
Microbiology Research Vol. 4 (3), pp. 197-203 [electronic copy] retrieved Feb. 4, 2012 from http://www.academicjournals.org/ajmr/PDF/Pdf2010/4Feb/Arora%20et%20al.pdf
Haque, S. (2011). Biochemical role of nitric oxide precursor and antibiotic against typhoid. Journal of Microbiology and Antimicrobials Vol. 3(8), pp. 217-220. [electronic copy] Retrieved Feb. 4,
2012 from http://www.academicjournals.org/JMA/PDF/pdf%202011/August/Haque.pdf