Microbiology Flashcards
Describe how you would identify a bacteria as Salmonella using Microbiology tests including differentiating it from Shigella? (4)
Salmonella is a gram-negative bacilli. Gram Stain= Pink. (1)
Bacilli Appearance= Rod shaped. (1)
MacConkey Agar tests for fermentation of lactose, Salmonella does not therefore plate remains clear (fermenters go pink). (1)
Do serotyping (API strip) to confirm Salmonella vs Shigella. (1)
What do beta lactam antibiotics target?
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Give four types of beta lactam antibiotics
Why are mycoplasma resistant to beta-lactams?
They have no cell wall. (beta lactams inhibit peptidoglycan synthesis)
What pathogen is most commonly isolated in chronic diarrhoea in someone with HIV?
Cryptosporidium parvum (protozoan parasite)
what is co-trimoxazole a combination of and what do they do?
co-trimoxazole = TRIMethoprim + sulfamethOXAZOLE
Inhibit folate synthesis
What shape are neisseria bacteria?
What shape bacteria is haemophilus influenzae?
How would you identify pseudomonas?
- gram neg rod
- non-lactose fermenting
- oxidase positive
Which gram positive bacteria are coagulase positive?
What stain is used for TB?
Zeihl-Nielson
What antibiotic can cause C. diff colonisation?
Clindamycin
Four steps of gram staining?
“Come In And Stain”
- Crystal violet: primary stain
- Iodine: binds to crystal violet and traps it in the cell
- Alcohol wash
- Safranin: counterstain
Why do gram positives and gram negatives appear different under staining?
Why do gram positives and gram negatives appear different under staining?
- Gram positive: purple due to thick peptidoglycan wall retaining crystal violet
- Gram negative: pink as they retain the safranin counterstain
How would you identify E. coli?
How would you differentiate pseudomonas from shigella/salmonella?
How would you differentiate between Shigella and Salmonella?
What shape bacteria are neisseria species?
What agar would you use to identify H. influenzae?
Give three bacteria that are gram negative and comma shaped.
What would a microbiologist see on a histology slide of TB? (weakly-gram positive aerobic bacillus)
Caseating granulomata
What class of antibiotic is ceftriaxone / cefotaxime?
What antibiotic can be given for prophylactic treatment to avoid meningitis?
Ciproflaxacin
What class of antibiotic is ciprofloxacin and how does it work?
Definition of a commensal microorganism?
The microorganism can be cultured from the host but isn’t causing disease (also known as colonisation or asymptomatic carriage)
Definition of an infection by a microorganism?
The microorganism can be cultured from the host and is causing disease
Definition of an opportunistic pathogen/infection?
refers to microorganisms that only cause disease when a hosts defences are somehow compromised
Definition of virulence/pathogenicity?
the degree to which a microorganism is pathogenic
What is acid fastness?
A microorganisms ability to resist decolorisation by acids during lab staining procedures
what are the two main forms of fungi?
how do yeast divide?
what does the cell wall of fungi usually contain?
what ending do anti-fungal drugs usually have?
what’s the most pathogenic candida species?
what’s the most pathogenic aspergillus species?
where do aspergillus fumigatus usually infect the body?
where does Candida albicans usually infect the body?
what two species of candida can cause thrush?
candida albicans
candida glabrata
what’s the name of the structures that mould grows by making?
give the names of two drugs that inhibit ergosterol synthesis in fungi.
into what three groups can worms be divided into roughly by appearance?
what’s the definition of the pre-patent period with worms?
what types of immunoglobulin are involved in the response to nematodes?
Two most common bacterial causes of cellulitis?
Antibiotics for cellulitis?
Main side effect of vancomycin?
nephrotoxicity
