Microbiology Flashcards
Most common bacterial infections seen in B cell deficiencies
"SHiNE SKiS": Strep pneumo HiB N. meningitidis E. coli Salmonella Klebsiella GB Strep
Most common infection for patients receiving TPN
Candidemia - candida species have pseudohyphae with blastoconidia, can be local or systemic infections
MCC of bacterial meningitis in adults
Strep pneumo
Cord factor
A mycoside and major virulence factor of TB that causes the bugs to grow in parallel chains, or a twisted “serpentine” pattern; it also inactives NTs, damages mitochondria, and induces release of TNFa.
Without cord factor, the mycobacterium can’t cause disease.
**Sulfides are responsible for the ability to live in MPs because they inhibit the fusion of the endosome with lysosome. Also a virulence factor, but not associated with growth in cords.
Why is Hib so bad?
it has a PRP (contains pentose monosaccharides) capsule that prevents phagocytosis.
The other Hi strains have regular hexose sugars and therefore don’t wreak quite as much havoc. Hence the importance of the vaccine.
Most common cause of febrile neutropenia with PNA?
- MCC is Gram positives
- also viral and fungal (Aspergillus) infection
- start broad spectrum Abx when NT count is
Most common manifestation of cryptococcus infection?
meningoencephalitis
- it’s an opportunistic pathogen in IC’d patients
- transmitted via respiratory droplets but rarely causes pulmonary sx; will not cause interstitial PNA
- there’s a cutaneous form that’s rare (
What does strep viridans adhere to?
tooth enamel and fibrin-platelet aggregates
- hence they are normal mouth flora, associated with dental work/caries, and can cause endocarditis on a damaged valve which would already have platelet aggregates on it
Amatoxins
- toxin from poisonous mushrooms, Amanita phylloides
- will get absorbed from GI tract, go to liver and inhibit RNA pol II from making mRNA - results in apoptosis
Treatment (in order) for Diphtheria infection
- Antitoxin (passive immunization)
- Antibiotics (Penicillin or Erythromycin)
- DPT Vaccine
Allergic Bronchopulmonary Aspergillosis
when someone with asthma or CF gets an allergy to Aspergillus colonization of the bronchial mucosa
- rarely symptomatic but can exacerbate asthma, or cause disease in IC’d
- can produce transient pulmonary infiltrates and sometimes progress to bronchiectasis
- occurs in 5-10% of corticosteroid-dependent asthmatics
- will find eosinophilia, elevated IgG and IgE against Aspergillus, and intense airway inflammation with mucus plugging
What is lipopolysaccharide?
it’s the capsule/endotoxin of E. coli and is composed of 3 parts:
1. O antigen
2. Core polysaccharide
3. Lipid A
Lipid A is responsible for endotoxic/Gram-negative shock when the bacteria are lysed
Koplik spots
Blue/white spots on erythematous base on the buccal mucosa - pathognomonic for measles
May progress to confluent, full-body maculopapular rash, then later SSPE
*Get the live attenuated vaccine!
What’s the GAS virulence factor that is most anti-phagocytic?
Protein M
