Microbiology: Basic Bacteriology Flashcards
What are spores?
Only in gram +. Resist dehydration, heat, chemicals
Is it gram positive or negative that has endotoxins?
Gram negative only.
What does the outer membrane contain?
Endotoxin (gram negative) and porins for transport
Peptidoglycan
Is a sugar backbone with peptide side chains bound together by transpeptidases
Do you have a cell wall in gram positive or gram negative?
Only gram negative
What does the silver stain test for?
Fungi (PJP, Coccidiodes, Legionella, Helicobacter pylori)
What is indicator media?
A colour change (conversion of lactose in E Coli) causes a colour change in the media
Endotoxins?
On outer cell membrane of gram negative, lipid A component of LPS, must be lysed to release. Less fatal than exotoxins, can’t make toxoids against. Cause fever, hypotension, DIC by activating TNF alpha, IL-1, IL-6. Meningococcemia and sepsis with gram negatives
What are the 6 ways in which exotoxins can work?
- Inhibit protein synthesis (diphtheria, pseudomonas aeruginosa, shigella and EHEC)
- Increase fluid secretion (entertoxigenic E coli, baccilus anthracis, cholera)
- Inhibit phagocytic activity (pertussis)
- Inhibit the release of a neurotransmitter (tetanus- can’t release glycine and GABA, botulism-can’t release Ach)
- Lyse cell membrane (clostridium perfringens and streptococcus pyogenes)
- Supertoxin release (staph aureus and strep pyogenes)-toxic shock syndrome
what does the endotoxin cause?
- Complement activation (histamine release, neutrophil chemotaxis)
- Macrophage activation (cytokine activation, fever and hypotension)
- Tissue factor activation (DIC)
What bug can cause rheumatic fever and glomerulonephritis?
(Group A strep) Strep pyogenes (pharyngitis, cellulitis, necrotizing fasciitis, impetigo, erysipelas, scarlet fever)
What are the 4 D’s of Botulism toxin?
dysphagia, dyspnea, dysarthria, diplopia
For lactose fermenting gram negative bacilli, what kind of stain do you use?
MacCon KEE’s agar- EMB agar-lactose fermenters grow purple and black and E Coli had green sheen
What is HUS?
hemolytic uremic syndrome caused by E coli O157, anemia, thrombocytopenia and acute renal failure
What bacteria can cause red jelly currant sputum?
Kleibsiella, also worry about pneumonia in alcoholics and diabetics, nosocomial UTIs and MDR
What can campylobacter cause?
guillian barre and reactive arthritis (likes to live at 42C) undercooked poultry and meat, unpasteurized milk, dogs, cats, pigs also risk factor
What are the spirochetes?
Borrelia, Leptospira, Treponema
What is lyme disease and how does it present?
Borrelia burgdorferi, transmitted by the Ixodes deer tick (natural reservoir is the mouse). Starts with erthema migrans (bullseye rash), then carditis, AV block, bells palsy, transient arthritis and myalgias, late disseminated can be encephalopathy and chronic arthritis
FACE-facial nerve palsy (bilateral), arthritis, carditis (cardiac block), erythema migricans
Doxycycline is first line, can you amox or cefuoxime in pregnant women and children
What is syphilis?
Caused by spirochete Treponema pallidum-
Primary- painless chancre-VDRL of fluid, dark microscopy
Secondary: maculopapular rash, painless wart like lesions
Tertiary: granulomas, aortitis, neurosyphilis, broad based ataxia
Congenital: rhagades, saddle nose, snuffles, CN8 deafness, notched teeth
Is VDRL sensitive or specific?
Very sensitive, but not specific. Need to think about PVDRL-pregnancy, viral illness, drugs, rheumatic fever, lupus and leprosy
When do you use a Tzanck stain and what does it show?
For HSV and shows multinucleated giant cells
When do you see atypical lymphocytes?
EBV
When do you see owl’s eye inclusions?
CMV
What does the monospot test?
Heterophile antibodies detected by agglutination of sheep/horse RBCs
What is HHV-8
Kaposi sarcoma (neoplasm of the endothelial cells) in immunocompromised HIV/AIDS, transplant patients, dark violaceous nodules/plaques
What is HHV-6/7
Roseola infantum- get fever first then diffuse macular rash
HSV1
Resp- dormant in trigeminal ganglia
HSV2
Sexual contact-latent in sacral ganglia
HHV-3
Varicella-shingles, latent in trigeminal ganglia, post herpetic neuralgia is common with shingles
Where do all RNA viruses replicate?
in the cytoplasm except for retrovirus and influenza (retro flu is outta cyt)
What are some common flaviviruses?
HCV, yellow fever, dengue, , west nile, zika (single stranded RNA), have envelope
Togaviruses?
rubella, chikungunya
What are the retroviruses?
HTLV and HIV/AIDS
What are the types of structures of viruses?
icosahedral and helical
What are the paramyxoviruses?
RSV, parainfluenza, measles, mumps
What type of virus is ebola?
Filovirus
What is different about negative stranded viruses?
need to bring their own RNA polymerase
What is rotavirus?
double stranded RNA virus. Most common cause of infantile diarrhea (no vaccine if intussception or SCID)
What is genetic/antigenic shift?
when one part of virus combines with a part of another virus (ie human flu A with swine flu A) sudden is worse than gradual
What causes the blueberry muffin appearance in babies?
Congenital rubella- extramedullary hematopoiesis- also causes deafness, cardiac abnormalities, cataracts, microcephaly etc
what are the paramyxoviruses?
RSV, parainfluenza, measles, mumps, HMPV, cause disease in children, all have F protein that-causes resp epithelial cells to fuse. Palivizumab is against the F protein- prevents RSV pneumonia in prems
What causes Koplik spots?
Measles- paramyxovirus, get red spots with white/blue center on buccal mucosa, usually prodromal fever then spots, then maculopapular rash face to trunk, down (cough, coryza, conjunctivitis). Vitamin A can reduce mortality/morbidity in malnourished.
What does mumps cause?
pancreatitis, parotitis, orchiditis
What infections are those with HIV/AIDS at risk of?
reactivating latent infections-TB, HSV, shingles, bacterial and fungal infections, coccidiodomycosis and non-hodgkins lymhoma
What are the normal skin/oropharynx/colon flora?
Staphylococcus epidermis-skin, oro-strep viridans, colon Bacteroides fragilis>Ecoli
What bugs are usually from aspiration?
anaerobes
What bugs do you see in CF?
Pseudomonas, S aureus, strep pneumonia, burkholderia cepacia
What’s a common bug for osteomyelitis?
Staph aureus, can think of neisseria gonorrhoeae with septic arthritis
What does the most common UTI bug show on stain?
USe MacConkey agar and it shows pink lactose fermentation (E. Coli)
What is the classic triad of toxoplasmosis in TORCH?
chorioretinitis, hydrocephalus, intracranial calcification, can also get blueberry muffin rash
What are the signs of congenital syphilis?
saddle nose, notched teeth, hydrops fetalis, , CN8 deafness, saber shins
What is Chancroid?
caused by haemophilus ducreyi (sexually transmitted), painful genital ulcer with exudate
What is granuloma inguinale (donovanosis)?
painless red beefy ulcer that bleeds (uncommon in US) caused by kleibsiella (cytoplasmic donovan bodies seen on microscopy)
What is lymphogranuloma venereum?
caused by chlamydia trachomatis- you get painless ulcers, but painful lymphadenopathy
What bacteria can cause bilateral facial nerve palsy?
Borrelia burgdorferi (lyme disease)
