Microbiology 4 (Dr Orange) Flashcards
What is the incubation period?
the time between contracting the infection (i.e. swallowing the organsim) and the first clinical symtpoms/ signs of infection
What avoidable circumstances are most infections in the community related to?
Cross-contamination of work surfaces/ utensils
Undercooking (insufficient heat to kill off pathogens), linked to inadequate defrosting of frozen food
Improper storage of food (inadequate refrigeration)
Poor reheating of food
What are the purpose of local microbiology laboratories in terms of when they find a GI infection? (2)
All GI infections reported promptly to local Health Protection Team
All isolates sent to Scottish Reference Lab
Where are all isolates from local labs sent?
Scottish Reference Labs
What do the reference labs do to isolates?
Collect them and perform further typing (linking of isolates across Scotland)
What is the role of health protection teams?
Receive reports of GI infections from local labs and send environmental health officers out to interview patients and find origin of infection
What is a common cause of healthcare-associated diarrhoea?
Clostridium difficile
What age of patients carry C diff as part of their normal bacterial flora?
Infants
Elderly (less commonly)
What causes the patient to become unwell with C diff.?
Production of toxins
What toxins are produced by C diff?
Toxin A (enterotoxin) Toxin B (cytotoxin)
What is the source/ vehicle of infection of C diff?
Present in bowel in small numbers in a number of people
When antibiotics prescribed, it kills off the normal competitive bowel flora allowing C diff to overgrow
Organism produces spores that survive in the environment dn are more resistant to disinfectants
Organism is transmitted from one patient to another
Symptoms of C diff?
Diarrhoea (sometimes bloody)
Abdo pain
Severe cases may progress to pseudomembranous colitis or bowel perforation
Management of C diff?
Depends on severity assessment:
Less severe = oral metronidazole
Severe = oral vancomycin
Prevention of C diff? (4)
Stewardship
Isolate patients
Hand washing (not alcohol)
Cleaning the environment
What type of bacteria is c diff?
Gram positive spore-bearing bacillus (spores more resistant to disinfectants)
There is no one good lab test for C diff? - true/ false
True
What lab tests can be performed for the diagnosis of C diff?
Screening test for presence of the organism (GDH)
If GDH positive, test for presence of toxin (toxin A and B)
Culture can be done if strain needs to be typed - not done routinely
Does the patient have c diff if the screening test is negative?
No
Does the patient have c diff is the screening test pos, toxin test pos?
Positive result
Does the patient have c diff is the screening test pos, toxin test neg?
Indeterminate result
What is the action plan if the lab tests for C diff are indeterminate?
Assess patient
Send repeat specimen (usually also indeterminate result also so have to make clinical decision - faeces usually smells of “horse shit” so ask experienced nurse if they think the patient has C diff
During what season are more cases of C diff seen?
Why is this thought to be the case?
Winter
Increased number of admission and possibly linked to the norovirus
Give an example of a hospital-acquired infection which is nationally surveyed?
C diff (can also occur in the community)
What 2 ribotypes of C diff are hyper-producers of toxin (leading to an increased morbidity and risk of death?
Ribotypes 027 and 078
