Review Cards Flashcards
3 UTI pathogens that give a positive Urease Test
Proteus
Morganella
Providencia
What does Proteus look like on a SBA plate?
Swarming
Why is Proteus the ideal UTI pathogen?
Breaks down urease!
This causes an increase in pH, crystal deposition, struvite stone formation, obstructive flow, and biofilm formation
Enterococcus spp resistant to Vanco but sensitive to Teico. What is it?
VanB
Want to know the species though, if its faecium or faecalis it’ll be worse then if its gallinarum or cassiflavus
How do you test for MRSA heterogenous resistance
Add NaCl to put the organism under osmotic stress which will induce the resistance
Cefoxitin best inducer
Put down a heavy inoculum because the resistance is rare
Main way to differentiate strep from enterococcus
PYR test (enterococcus is positive)
How to figure out what species of enterococcus you have
- Motility (90% of gallinarum is motile, so only useful if you do see motility)
- Pigment (cassiflavus is yellow on a white cotton swab)
- Glucopyranoside test (gallinarum and cassiflavus are positive)
2 pathogens that are most likely involved in a hip replacement infection
Staph aureus
Coag negative staph (longer lag period)
16S PCR
Ribosomes have conserved and variable regions
Primers for conserved regions (will tell you if you have a bacteria or not)
Variable regions will tell you what organism it is
3 problems with 16S PCR
Has to come from a sterile site
Easily contaminated
Has to be a monomicrobial infection
Why is P. falciparum worse than the others?
There are way more parasites!
And they can infect any red cell regardless of how mature they are
Factors/variables that can affect the types and sizes or zones seen using Kirby-Bauer disk diffusion?
Thickness of media Temperature of incubation Inoculum size pH Inoculum density Potency of the disk Disk spacing Incubation time Timing of disc application Reading of the disc
What phenotype is related to
- erm
- met
- target site modification
2. efflux pump
What factors help improve the recovery of pathogens from the blood and/or minimize the risk of reporting a contaminant
Let the first few mLs drain to remove the skin plug
Take multiple bottles for multiple veni-punctures
Adequate volume of blood (more than 30mL)
Grow at least one bottle anaerobically
Have appropriate dilution between blood and media
3 organisms dependent on capsule formation
Haemophilus influenza
Strep pneumonia
Neisseria meningitis
What is a big risk factor for infection by encapsulated organisms?
Being asplenic!!
CAMP test is positive for…
Listeria and group B strep
What are some anti-pseudomonal antibiotics?
Piperacillin Ciprofloxacin Cefazitime Tobramycin Carbapenems
Stenotrophominas maltophilia is susceptible to…
Septra
2 common bacterial causes of otitis media
Strep pneumonia
Haemophilus influenzae
Throat swab from 5 year old, grows on blood agar – small gram negative coccobacilli, ox and catalase +, oxidizes glucose and maltose
What is it and what do you do
Neisseria meningitis
DO NOTHING! Dont even mention it
What is an acid fast stain look for and how does it work?
Looks for mycobacteria
Mycolic acid will retain the dye, even in the presence of a harsh acid
Most common STI worldwide
HPV
then herpes
How do bacteria become resistant to the quinolones
Point mutations in the A subunits of DNA gyrase and Topo 4 to reduce the affinity of the drug for them
Also efflux pumps and down regulation of porin channels
Large gram + bacilli is likely…
Bacillus or Clostridium
Differentiate based on aerobic (B) or anaerobic (C)
Purpose of transport media
Maintain viability but do not allow growth
3 organisms that rarely represent true bacteremia
Corynebacterium
Bacillus
Propionibacterium
What do you treat for cat bites?
Amoxicillin and clavulanic acid
Because you can’t use an oral cephalosporin and you get oral anaerobes in there that produce beta lactamases
Viruses that cause CNS infections (4)
HSV
Rabies
Enterovirus
Arbovirus
Bloodborne viruses (3)
HIV
HCV
HBV
Viral exanthem viruses (6)
measles rubella roseola parvovirus B19 enterovirus varicella
Sexually transmitted viruses (3)
herpes
molluscum contagiousum
herpes
Respiratory viruses (7)
rhinovirus coronavirus enterovirus respiratory syncytial virus parainfluenza virus adenovirus influenza
GI viruses (5)
norovirus rotavirus astrovirus enteric adenovirus hepatitis A and E
Rheumatoid factor
IgM that binds the Fc portion of IgG
Interferes with IgG assays
Causes false positives/negatives
How is HIV/HCV/HBV detected?
Serology
Start with a sensitive screening assay (overly sensitive)
Need a confirmation assay that is highly specific
Two tiered testing!!
HIV Diagnosis
- 4th generation EIA
- If negative, repeat over time
- If positive, confirm with a Western Blot or Immunoblot
- If Immunoblot is problematic, confirm with PCR
- Monitor viral loads with real time/quatitative PCR
How are influenza symptoms different from other respiratory viruses?
Fever Muscle pain Malaise No runny nose or sore throat Cough Headache Fatigue, Weakness
Viral latency
Remains in DRG or trigeminal nerve and can reactivate at a later time
2 viruses that can remain latent
Herpes
Varicella Zoster Virus
Consequences of reactivation
Zoster Cold sores Genital/oral herpes Shingles Encephalitis
Pathogenesis of herpes
Primary exposure or reactivation
What type of CNS infection does herpes cause?
Encephalitis
Virus families with bats as the host
Bunyaviruses
Filoviruses
How do you test for measles
RT PCR from NP, throat or urine samples
Could also do serology
4 VHF families and an example of each
Arenaviridae (Lassa Fever)
Filoviridae (Ebola)
Flaviviridae (Dengue)
Bunyaviridae (Hanta virus)
Best way to diagnose spirochetes
Serology!
Lyme needs a 2 tiered testing
Leptospirosis can do PCR from stool or urine early enough
Syphilis needs treponemal and non treponemal testing
RPR for syphilis
Rapid Plasma Reagin
Non-treponemal test
Easy to monitor disease
Used world wide
What is a 1. Bacteria 2. Virus 3. Toxin used for bioterrorism
- Yersinia pestis, Bacillus anthracis, Francisella tularensis
- Smallpox (Variola virus)
- Botulism toxin
Methods of viral transmission (11)
Aerosol Droplet Contact Fomites Fecal oral Food or water borne Vertical Sexual Zoonotic Vectors Parenteral
Vector borne viruses (4)
Franciscella tularensis
Borrelia burdoferi
Rickettsia spp
Orientia tsutsugamushi
Zoonoses viruses (3)
Rabies
Ebola
Influenza
Vaccine preventable diseases (likely to be on exam)
8
Hep A/B MMR Varicella Yellow fever and JEV Smallpox Influenza HPV Rotavirus
Viruses where antiviral treatments are available (5)
Herpes HCV and HBV Varicella zoster HIV Influenza
If you forgot to take a CSF sample when someone has bacterial meningitis and you’re already treating them, what test would you do to see what bacteria they have?
16S RNA PCR
Helpful to detect outbreaks
How does C diff causes disease?
Ingest spores Survive through gut Activated by bile salts Colonize mucosa Mucosal disturbance Grow and produce toxin Get disease
2 ways to detect outbreaks
- Pulsed field gel electrophoresis (to get a fingerprint and then compare with the outbreak strains)
- Sequence the whole genome
