Title 23. STUDY OF INFECTIOUS DISEASES.pdf ✅

PHARMD GURU Page 1 STUDY OF TYPHOID: The causative agent of typhoid is a bacteria, Salmonella typhi belonging to family Enterobacteriaceae. The bacteria is a gram negative, rod shaped bacteria in single arrangement. It has perichitous flagella for motility, it is non spore forming, facultative anaerobic, and capsular organism. VIRULENT FACTORS: The bacteria causes the infection due to the following virulent factors - H antigen present on the flagella, O antigen is a somatic antigen present on the body surface of the organism, Vi capsular antigen which Is a capsular producing antigen, endotoxin called lipopolysaccharlde, secretory protein called invasin which enters the non- phagocytic cells of the host. Due to these virulent factors the bacteria can escape from the host's immune mechanism. MECHANISM OF INFECTION: Salmonella typhi enters the host through the contaminated food and water, and from the stomach it enters into the Intestine. In the intestine it crosses the epithelium and reaches systemic circulation and enters into various tissues and organs. SIGNS AND SYMPTOMS:  In the first week of infection fluctuating bradycardia, malaise, headache, cough, and abdominal pain were observed.  In the second week of Infection high fever, bradycardia, delirium, rose colour spots on chest and trunk region, abdominal pain, diarrhoea or constipation are observed.  In the third week many complications like intestinal haemorrhage i.e., perforation mainly in the ileum region, where the organism enters the systemic circulation and cause various metastatic complications like abscesses in the liver, cholecystitis (inflammation of gall bladder), endocarditis (Inflammation of endocardium), osteitis and also oscillating type of fever usually high in afternoon, dehydration, delirium, and decrease in the platelet count leading to Internal bleeding. STUDY OF INFECTIOUS DISEASES
PHARMD GURU Page 2 DIAGNOSIS:  The diagnosis can be done by clinical symptoms, patient history, use of serological tests like Widal test in which the blood sample from the patient is taken and mixed with specific antibodies which react with H and O antigens of the bacteria present in the blood and forms antigen-antibody agglutination. It is a presumptive test.  Other confirmation tests are isolation test in which the cultures from the blood sample are isolated by using Macconkey’s agar/EMB agar media, and biochemical characterization (non lactose forming and non gas producing organism) are used.  The advanced techniques like PCR and blot tests are also used. MODE OF TRANSMISSION: The main source of transmission of typhoid is vomiting, fecal and urine disposals from the infected person. It may be transmitted directly or indirectly by carriers like flies. The transmission can be done by contaminated water and food, improper hygienic and sanitary conditions. IMMUNIZATION: The Immunization can be done by vaccination. The Vi capsular antigen vaccine or killed bacterial vaccine is given by parenteral route. The Immunity towards the Infection may be for only 2 — 3 years. PREVENTION AND CONTROL: The typhoid infection can be prevented by practicing proper sanitation and hygienic life style, careful food preparations, controlling flies, water purification, complete treatment for the infected persons, and educating the public about the disease. TREATMENT:  The first choice of the drug is fluoroquinolones e.g. ciprofloxacln and third generation cephalosporins e.g. ceftriaxone, cefotaxime, and cefixlme.  Other antibiotics used are ampicillin, chloramphenicol and combination of trimethoprim-sulfamethoxazole.  If complete drug therapy is not implemented, then the organism may get drug resistance and becomes difficult to remove the infection completely.
PHARMD GURU Page 3 STUDY OF TUBERCULOSIS:  The causative agent of tuberculosis is Mycobacterium tuberculosis belonging to the family Mycobacteriaceae.  The other strains that cause tuberculosis are M. bovls, M. africanum, M. carnetti, M. microti etc.  The morphological features of the bacteria are that it is a small, straight, slender rod shaped, non-motile, non-capsulated, non-spore forming, aerobic organism.  The presence of mycolic acids in the cell wall is a characteristic feature due to which the bacteria gets resistance towards various antibiotics and disinfectants, and escapes from the phagocyte mechanism of the host.  The bacteria is Identified by the acid fast staining as it does not take up the normal stains due to the presence of mycolic acids in the cell wall. Thus it is differentiated as acid fast positive bacteria. PATHOPHYSIOLOGY:  Mycobacterium tuberculosis enters the respiratory tract through the nasal route and then enters the alveoli.  Due to the presence of mycolic acids in the cell wall, the bacteria escapes from the phagocyte action of the alveoli.  But the other immune cells like fibroblasts, cytotoxic T cells, and macrophage lines deploy around the bacterium. This deployment of bacterium is called as tubercle.  The tubercle is very minute in size which may not be noticed.  When the immunity of the host becomes weak and the immune cells are unable to control the bacterium, this bacterium starts to multiply and the tubercle grows in larger size.  The continuous multiplication of bacteria within the tubercle leads to the rupture of alveoli and affects the respiratory system wherein the bacteria enters the circulatory system.  Through the systemic circulation the bacteria reaches different tissues and organs by forming a granuloma.  The infection within the respiratory tract is called pulmonary infection and the infection within the systemic circulation is called extra pulmonary tuberculosis.
PHARMD GURU Page 4 SIGNS AND SYMPTOMS:  The general symptoms are fever, chills, night sweats, loss of appetite, severe fatigue, persistent and worsening cough.  The pulmonary signs are chest pain, cough with sputum, sometimes blood in the sputum is noticed due to rupture of alveoli.  The extra-pulmonary signs are observed depending on the organ which is affected by the bacteria.  TB pleurisy, CNS - meningitis, lymph - scrofula in neck, bones and joints - pott spine, liver - hepatitis, skin - ulcer, and genito urinary infection.  If the tuberculosis is widespread throughout the body it is termed as miliary tuberculosis. DIAGNOSIS:  If the symptoms persist over a period of two to three weeks, it is called active tuberculosis.  This can be diagnosed by chest x - ray, multiple sputum culture by acid fast staining technique, biopsy cultures of infected tissue or organ, POR, adenosine deaminase test etc.  Latent tuberculosis is which wherein no clinical symptoms were observed.  It is diagnosed by Mantoux tuberculin skin test, and advanced tests like α - gold test or ELISA. MODE OF TRANSMISSION: The major route of transmission of tuberculosis is aerial route i.e. through the droplets of cough and sputum from the infected person. Other routes of transmission are sharing fomites or objects, and contaminated food. IMMUNIZATION: The immunization of tuberculosis was done through a vaccine known as BCG (Bacillus Calmette Guerin) vaccine, which is a successful live attenuated vaccine. PREVENTION AND CONTROL: The tuberculosis can be prevented by proper vaccination to infants, proper diagnosis and medical therapy, avoiding aerial route of transmission by using masks, proper diet and hygienic life, and educating the public.