History, Hygiene And Hospital Infection

Question 1

What is the difference between endogenous and exogenous infection?

Answer 1

• EXOGENOUS is caused by bacteria from the outside environment or possibly from another organism e.g. Malaria
• ENDOGENOUS is caused by bacteria from the host’s microbiota e.g. Urinary tract infections

Question 2

What is meant by colonisation of an organism?

Answer 2

Multiplication and growth of the organism once it has entered and established inside the host

Question 3

What is meant by the normal microbiota of a host?

Answer 3

Colony of bacteria that is asymptomatic and does not contribute to infection, but may be involved in the host’s normal mechanisms

Question 4

Define carrier status

Answer 4

Presence of the infective agent in the normal microbiota of the host

Question 5

What is meant by direct progression of the infective agent?

Answer 5

• Entry or establishment of the infective agent in the host is sufficient to cause infection that may be asymptomatic
• Spread and multiplication of the organism may cause damage or dysfunction to the host thus the infection becomes symptomatic

Question 6

How can you prevent the transmission of infection?

Answer 6

• Eliminate the microbe from the immediate source or reservoir
• Isolate the host from the immediate source by ELIMINATING THE MODE OF TRANSMISSION

Question 7

What is R0?

Answer 7

RATE AT WHICH AN INDIVIDUAL INFECTION PRODUCES NEW INFECTION IN NEW INDIVIDUALS

• R0>1 the infection propagates
• R0

Question 8

What intervention factors may be used in the hospital setting to prevent spread of infection?

Answer 8

• Antibiotic restriction
• Reduce cohorting of staff
• HANDWASHING

Question 9

What factors affect the transmission of infection?

Answer 9

• Reservoir
• Immediate source
• Mode of transmission
• Susceptible host

Question 10

Define Koch’s postulates of 1882

Answer 10

• Agent must be present in every case of the disease
• Agent must not be present in cases of any other disease
• Agent must be able to reproduce the disease in unaffected individuals and be isolated from the diseased organism and grown in culture

Question 11

What are the main problems with adhering to Koch’s postulates?

Answer 11

• Most diseases are multifactorial
• One exposure can cause several diseases
• Disease is usually as result of interaction between the host, agent and environment