Flashcards in gram negative rods- lecture Deck (28)
what is pathogenicity
ability of organism to cause disease
what is virulence
severity of disease caused by organism
What are some organism determinants of pathogenicity/virulence?
Adhesions, toxins and antibiotic resistance
What are lipopolysaccharide endotoxins?
Part of the GNB cells wall, immune stimulant, responsible for sepsis syndrome
what are the classifications of UTIs?
Lower vs upper & complicated vs uncomplicated.
There is also asymptomatic bacteriuria
Where do lower UTI's occur? Where do upper?
-Lower- urethritis, prostatitis, cystitis (bladder infection)
-Upper-pyelonephritis (inflammation of kidney)
What is a complicated UTI
AUTI with structural abnormality of the urinary tract (stone),
most common pathogen causing UTI
- Escherichia coli
2nd most common pathogen causing UTI (prevalent in what group in society?)
- Staphylococcus saprophytic (young females)
what are some risk factors for UTIs
female sex (shorter urethra), increased age (incomplete bladder emptying, poor perineal hygiene, altered vaginal flora), structural urological disease (stones, instrumentation, enlarged prostate etc)
what sources of information could you use before you have the results of the culture susceptibility results?
local antibiogram, australian therapeutic guidelines, prior microbiology results
what is a community acquired infection
o onset of infection whilst residing in the community with within the first 48 hours of admission to hospital
what is the community onset, healthcare associated infection
same as community acquired but has had healthcare contact in the last 90 days
what is a hospital acquired infections
infection that starts about 48 hours after admission to hospital
what are the most common cause of hospital acquired infections
gram negative rods
what are the most common GNBs causing HAI
E coli (and pseudomonas)
In surgical sites, what bacteria are we most likely to see?
GNBs and GPBs
Which bacteria are you most likely to see in blood infections?
How does the oxidase test distinguish Enterobacteriaceae from Pseudomonas aeruginosa?
Enterobactiaceae is oxidase negative, while Pseudomonas is positive
What are the broad groupings of GN rods?
3. Oxidase positive fermenters
4. Miscellaneous fastidious
5. Campylobacter & Helicobacter
List some of the important genus of Enterobacteriaceae
What disease does E.coli cause?
Responsible for 80% UTIs
Also cause food poisoning and diarrhoea
What are the clinical differences between community acquired and hospital acquired infections with GN bacteria?
-Hospital acquired infections are much more likely to be resistant to antibiotics. -There is significant alteration in bowel flora in the hospital, increased colonisation with gram negative rods and gram positive cocci is common
-Lots more MRSA
-Gram negatives frequently cause pneumonia and UTIs, as well as blood stream infections
Which enterobacteriaceae causes enteric illness?
Escherichia coli caused nearly 50%, then Pseudomonas, as well as Klebsiella and Proteus
What type of disease do Pseudomonas species cause?
Pneumonia, UTIs and bacteraemia
What are some of the different morphologies of GN rods?
Medium sized - Acinetobacter
Tiny cocco-bacillary - Brucella
Pleomorphic: coccobacillary/filamentous - Haemophilus
Coiled - Streptobacillus
Uniform - Pseudomonas
What makes Pseudomonas such a significant bacteria?
It has a biofilm formation, which makes it resistant to disinfectants and antibiotics, and allows it to survive in nutrient poor environments