Microbiology Flashcards
How long do the results of antibody detection take?
Test may be rapid, but takes minimum of 2 weeks from exposure to develop antibody response
What can you tell from macroscopic bacteriology?
The appearance, colour and smell
Name some gram positive cocci
Staphylococci , streptococci, enterococci
Name some gram negative cocci
Neisseria, moraxella
Name some gram positive bacilli
Actinomyces, bacillus, clostridia, diphtheria, listeria monocytogenes
Name some gram negative bacilli
E. Coli, campylobacter, pseudomonas, salmonella, shigella, proteus
What are gram positive coccus chains?
Streptococcus
What are gram positive coccus clusters?
Staphylococcus
Purple coccus chains. Beta haemolysis. What is this?
Beta haemolytic strep, can be split into antigenic groups
Purple coccus chains. Alpha haemolytic. Sensitive to optochin test, what is it?
Strep pneumonia
Purple coccus chains. Alpha haemolytic. Resistant to optochin test. What is it?
Viridans streptococci
Clusters of purple coccus?
Staphylococcus
Clusters of purple cocci. Coagulase positive.
Staph. Aureus
Clusters of purple coccus. Coagulase negative, what is it?
Coagulase negative staphylococcus
Pink bacilli. Red on macconkey plate, what is it?
(Lactose fermenting) enterobacteriaceae, e.g. E.coli, klebsiella. Do a sensitivity test and biochemical identification.
Pink bacilli. Colourless/white on Macconkey agar, what is it?
Non-lactose fermenting. Shigella, salmonella, pseudomonas, proteus.
Pink bacilli. Colourless on macconkey agar. Positive oxidase test, what is it?
Pseudomonas sp
Pink bacilli. Colourless on Macconkey plate. Negative oxidase test, what is it?
Enterobacteriaceae. Proteus, shigella
What colour is beta-haemolytic strep?
It is clear
What colour is alpha haemolytic strep?
Green
What are the sterile sites in the body?
Blood, CSF, pleural fluid, peritoneal cavity, joints, urinary tract, lower respiratory tract
What sites of the body would you expect to culture normal flora?
Mouth, skin, vagina, urethra, large intestine
What do the White/colourless colonies (macconkey) and pink colonies (XLD) have in common?
Non-lactose fermenting
Where is normally colonised by a range of bacteria including staphylococcus epidermidis, corynebacterium spp, proprionibacterium acne and enteric bacilli?
The skin
Where is usually harmlessly colonised by a alpha-haemolytic strep, micrococci, corynebacterium, non-pathogenic neisseria?
Oropharynx
Where is clostridium and bacteroides and enterococci, common?
In the large intestine
Why do skin flora like to live on the skin?
They like the dry, acidic conditions
Where is harmlessly colonised by streptococcus, bacteroides and lactobacillus acidophilus? And why?
The vagina, they like an acid medium and produce lactic acid to keep the vaginal secretions acidic
What is a beta-haemolytic strep of lance field group A?
Strep pyogenes
What are the two main approaches to viral diagnosis?
PCR and other nucleic acid amplification tests (NAAT). Serology
What are the advantages and disadvantages of PCR?
:) It is sensitive and quick. :( Because it is sensitive it is vulnerable to laboratory contamination. It only detects nucleic material complimentary to the primer sequences used so it can confirm or deny but not diagnose
What is the antibody text for hepatitis A?
IgM and IgG
What are the antibody tests for hepatitis B?
Core antibody IgM and IgG. Surface antibody, e antibody
What are the tests for hepatitis C?
Total (IgM/IgG) antibody and hepatitis C RNA
What are the antibody tests for hepatitis E?
IgM and IgG
What are the common organisms that cause urinary tract infection?
E.coli, proteus mirabilis, klebsiella, coagulase negative staph, enterococci
Why is a midstream urine test used?
So that any organisms colonising the external urethra are flushed out first and that the collection truly reflects the urinary within the bladder
What organisms have a particular capacity to form abscesses?
Staph aureus and anaerobes
Where are streptococci?
They are adapted to colonise the skin and are able to spread through the cutaneous and subcutaneous tissues as a result of the release of spreading factors
How long does a result of a culture take?
Days
Where is staph aureus? How does it spread?
It is adapted to colonise the anterior nares. It will infect skin and soft tissues because it produces a number of factors including coagulase, which coagulates plasme
Where and how do anaerobes infect?
They can be involved in deep soft tissue infections and probably get to the site by haematologist spread from the guy or by direct spread from the skin
What are patients with skin infections generally treated with?
Antibiotics active against strep and staph, beta-lactams, penicillin and flucloxacillin
How do you generally treat wound infections?
Broad-spectrum antibiotic such as cephalosporin and metronidazole to cover anaerobes
What is chocolate agar used for?
Aerobic pathogens
What is blood agar used for?
Anaerobic pathogens
What two species cause TB
Mycobacterium tuberculosis and mycobacterium bovis
What’s the commonest cause of pneumonia?
Streptococcus pneumoniae
