Lecture 8 - Pathogenic Microorganisms

8/13/2019 Lecture 8 - Pathogenic Microorganisms

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Pathogenic Microorganisms

Dr. Linroy Christian


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Salmonellosis Etiologic agent Salmonella

Common species; Salmonella enteritidis and Salmonellatyphimurium

Gram negative, rod-shaped bacterium Facultative anaerobe motile

Source Poultry and poultry products and faecally contaminated food

and water

Pets, in particular reptiles, carry Salmonella Mode of transmission

Faecal-oral route through ingestion of undercooked,contaminated food


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Salmonellosis

Morbidity Salmonella are often the most isolated pathogen

from faeces in many countries. The US generally

reports 40,000 cases per year of Salmonellosis Mortality

If left untreated, Salmonellosis can result in death.In the US over 600 persons die each year. Theimmunocompromised, children and the elderlyare most likely to get and succumb toSalmonellosis


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Salmonellosis Symptoms develop within 12-72 hours and

usually last between 4 to 7 days Symptoms may include:

Diarrhoea Fever Abdominal cramps

Symptoms are generally self-limiting, but may

require antibiotic treatment Infection may also spread to the bloodstream andother body sites and may lead to death ifantibiotic treatment is not received


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Salmonellosis

Persons with diarrhoea eventually recover, butmay be carriers for several weeks

Some individuals may develop ReitersSyndrome:

Joint pain Irritation of the eyes

Painful urination Reiters syndrome may lead to chronic

arthritis


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Salmonellosis

Treatment Rehydration or IV fluids Antibiotics are not generally necessary

If the infection has spread from the intestines,antibiotics may be used such as ampicillin,gentamicin or ciprofloxacin

Some salmonella are resistant to antibioticsdue to use of antibiotics in animal feed


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Salmonellosis

Prevention Cook food thoroughly and avoid food and drink

made with raw eggs and raw unpasteurised milk Avoid undercooked meat and poultry Wash hands and clean kitchen and work surfaces

thoroughly Wash hands after handling pets, especially reptiles

and birds Avoid cross contamination of cooked food with

potentially contaminated raw food


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Tuberculosis

Etiologic agent Mycobacterium tuberculosis Rod-shaped, acid fast bacterium aerobic

Mode of transmission Transmitted from person to person via droplet nuclei

when an infected person coughs, sneezes or talks The inhaled bacterium subsequently infects the lungs


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Tuberculosis

Morbidity In 2005 there were in excess of 14 million cases

world wide Mortality

In 2005, greater than 1.5 million people diedworld wide


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Tuberculosis TB infection may be latent or infected individuals

may develop TB disease Latent TB

The bacterium is in the body without infection orsymptoms and the infected individual is incapable ofspreading the disease

TB disease Individuals are infected with bacteria that are actively

multiplying Symptoms develop and disease may be spread from

person to person


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Tuberculosis symptoms include weakness, weight loss, fever,

loss of appetite and night sweats Infection of the lungs include coughing for more

than 3 weeks, chest pain and coughing blood Infection may spread to other parts of the body If exposed to an infected individual for prolonged

periods then it is advisable that a diagnostic testbe done to determine if infection occurred

Tuberculin (Mantoux) test QuntiFERON TB-Gold


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Tuberculosis Treatment

Latent Isoniazid for 9 months is the preferred treatment

TB disease Isoniazid, rifampin, ethambutol and pyrazinamide daily for 8

weeks followed by daily isoniazid and rifampin for 18 weeks Regime should be closely adhered to Monitoring for drug resistance should be done

BCG vaccine Not approved for use in many countries with the exception of the US Vaccine generally 60-80% effective


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Tuberculosis

Protection of health care workers Appropriate hospital policy

Assignment of responsibility Standard procedures Vaccination Screening System evaluation

Environmental control Respiratory protection


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Hepatitis

5 types are classified as Hepatitis viruses A, B, C, D and E

3 are transmitted through blood and bodilyfluids

B, C and D All cause infections of the liver of varying

degrees of severity


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Hepatitis A Transmitted from person to person via faecally

contaminated food Symptoms include jaundice, fatigue, abdominal

pain, loss of appetite, nausea, diarrhoea andfever

Symptoms may persist for months Lifelong immunity develops following recovery

Vaccine available Good hygienic practices are important for

prevention


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Hepatitis B Transmitted from person to person via blood and body

fluids Symptoms include jaundice, fatigue, abdominal pain,

loss of appetite, nausea, vomiting and joint pain Long-term infection may develop and may lead to

cirrhosis of the liver, liver cancer, liver failure and death Vaccine available

Drugs such a lamivudine used to treat chronic disease Special precautions required for health care workers


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Hepatitis C Transmission via blood from person to person Majority of individuals show no signs or symptoms Symptoms include jaundice, fatigue, abdominal pain,

loss of appetite, nausea and dark urine Infections is generally chronic in nature and may

include chronic liver infection, liver disease andcirrhosis

No vaccine available Interferon and ribavirin are approved for treatment


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Hepatitis D Transmitted from person to person via blood and

body fluids Can develop as a co-infection with Hep. B

Symptoms include jaundice, fatigue, abdominalpain, loss of appetite, nausea, vomiting, joint painand dark urine

Hep. B vaccine can be given to prevent co-infection

Chronic infection may be treated with interferon Liver transplant may be necessary


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Hepatitis E

Transmitted via ingestion of faecallycontaminated food and drink

No chronic infection Symptoms include jaundice, fatigue,

abdominal pain, loss of appetite, nausea,vomiting and dark urine

Prevention through proper hygiene

Lecture 8 - Pathogenic Microorganisms

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