Lab results Flashcards
What would it mean if wound swab came back positive for colliforms?
They are colonising flora- not pathological
What do you use to do strep grouping?
Lancefield latex test
What would positive surface antigen represent? e.g. of Hep B
ongoing or previous infection
What would positive surface antibody represent? e.g. Hep B
Immunity
What would core total antibody represent? e.g. Hep B
body starting to respond to infection - shows past/current infection
In terms of antibodies and antigens, would would indicate acute infection of Hep B?
surface antigen +
core total antibody +/-
surface antibody -
In terms of antibodies and antigens, would would indicate past infection and immunity of Hep B?
surface antigen +
core total antibody +
surface antibody +
What rapid test can be done in A&E to check for causes of pneumonia?
Strep pneumo + legionella urine test - looks for antigen
What is normal flora on a genital swab?
lactobacilli and staph aeureus
- staph a is a worry if from retained tampon, penile swap or if heavy and pure
How do you diagnose UTI in catheter users?
not from + dipstick - urine catheters can colonise within 6 hours - must diagnose from symptoms (e.g pyrexia, unwell, confused, increased WCC and CRP)
How would you identify pseudomonas in a culture?
- bacilli
non-lactose fermenting
+ oxidase
What are some commonalities and differences between staph aureus and epidermidis?
both gram + cocci
clusters = staph
+ coagulase = staph aureus (thickens, white, golden clusters on blood agar)
- coagulase = staph epidermidis (white clusters on blood agar)
What do you use to diagnose TB and why?
Ziehl-Neelson stain
TB has high myocolic acid in cell wall so is resistant to gram staining due to high lipid content
What is a gram + cocci chain and alpha haemolytic, not sensitive to optichin? Where does it come from and what can it cause?
strep viridans
from mouth
can cause endocarditis
What are the results that show H. influenza?
gram - bacili
on chocolate agar
What are the bacteria that cause vomiting in gastroenteritis?
staph aeureus
bacillus cereus
How would you identify enterococci in a culture?
gram + cocci
non-haemolytic or beta haemolytic
What are the main anti-microbials for gram + cocci?
strep - Beta lactams
staph - flucloxicillin
What does MRSA stand for? How would you treat it?
methicillin resistant staphlococcus aureus
treat with vancomycin
What is the most common cause of meningitis in healthy individuals and how do you identify it?
neisseria meningitidis
gram - diplococcus
no haemolysis on BA
rash
What are the types of gastroenteritis and the main cause?
food related - salmonella, campylobacter, staph aureus, bacillus careus, clostridium perifringens, E. coli
infectious - shigella, vibriocholerae, viral (SRV, rotavirus)
antibiotic related - C. difficile
What is the most common type of fungus?
candida
What is the broad spectrum treatment for meningitis?
cefotaxime
How would you treat viral meningitis once identified?
acyclovir
What identifies S. pneumoniae?
gram + coccus, chains
alpha haemolysis (green)
sensitive to optochin
How do you identify viruses and what are the pros and cons?
PCR - polymerase chain reaction
fast, v. sensitive
but you need to know the virus you are looking for
What is the order of antibody appearance?
IgM first and trials off
IgG peaks and appears later but stays up for life
Give an example of Lancifield group D enterococci
enterococci fecalis
What are the 4 stages of gram staining?
crystal violet - iodine - decolourisation (+ keeps purple stain) - counter stain (fuchsin, - shows pink)
