Test q's Flashcards
How does meningococci enter the blood?
from the pharynx- via pilus-mediated adherence to and penetration of the mucosal epithelium
What is n meningitidis’ virulence factor?
- sex pilus
- produces an IgA protease that facilitates survival by destroying antibodies
sputum gram stain shows many neutrophils but few or no organisms
Legionella pneumonia
very high fever in a smoker with diarrhea, confusion, and cough
Legionella pneumonia
Why cant legionella gram stain?
bc they have unique lipopolysaccharide chains on the outer membrane that inhibit gram staining
What is staph aureus’ virulence factor that is bound to the peptidoglycan wall?
Protein A: binds to the Fc portion of IgG at the complement binding site thus preventing activation of complement
= decreased opsonization
What substance is SECRETED by staph?
Hemolysin: can produce hemolysis and destruction of neutrophils, macs, and platelets
Which bacteria have the ability to take up free DNA from the environment (transformation)
Strep pneumo
H influ
Neisseria meningitidis
What bacteria are responsible for secondary bacterial pneumonia?
- Strep pneumo
- Staph aureus
- H influenzae
What organism has a lipooligosaccharide
N meningitidis
What is significant about N meningitidis’ LOS?
- It correlates with the outcome of the disease
- It causes sepsis by induction of inflammatory response (interacts with toll like receptor 4)
- Cause of cutaneous petechiae and hemorrhagic bullae
- Causes Waterhouse-Friderichsen syndrome
What is the major virulence factor of Group A strep?
Protein M: inhibits phagocytosis and inactivates complement
Streptolysin O MOA?
- found on group A strep- strep pyogenes
- lyses erythrocytes and PMNs but does not convey resistance to phagocytosis
budding yeast with a thick capsule
Cryptococcus
What does the DPT vaccine target?
the binding component (B subunit) of Diptheria’s exotoxin
- antibody binding prevents the exotoxin from attaching to host cell membrane and preventing disease
In a pt with bronchial asthma and CBC with eosinophilia, what do you suspect?
- Aspergillus
- Allergic Bronchopulmonary Aspergillus
- seen in steroid dependent asthmatics
How does typhoid fever cause death?
- causes inflammation within Peyer’s patches leading to intestinal hemorrhage and gut perforation
- polymicrobial peritonitis and sepsis
Pt presents with abdominal cramping, low fever, constipation and salmon colored rose spots on the abdomen, plus hepatosplenomegaly
Salmonella typhi
What do the different HIV structural genes encode:
- Gag
- Pol
- Env
- Gag = nucleocapsid proteins p24 & p7
- Pol = reverse transciptase
- Env = envelope glycoproteins ie gp120 and gp41
What is the only gram + bug with an endotoxin?
Listeria
Stain with carbolfuschin = what bugs?
Acid fast stain = Ziehl neelsen: Nocardia and Mycobacteria
Giemsa stain?
- Chlamydia
- Borrelia
- Rickettsia
- Trypanosomes
- Plasmodium
mucicarmine = ?
Cryptococus, stains the thick polysaccharid capsule red
Catalase positive organisms?
PLACESS: pseudomonas listeria aspergillus candida e coli s aureus serratia
What are the conjugated vaccines and why are they conjugated?
for capsular antigens- a protein is conjugated to the polysaccharide antigen to promote T cell activation and subsequent class switching- a polysaccharide antigen alone cannot be presented to T cells (only IgM would be produced) ex) H influenza type B and Meningococcal
What are the urease positive bugs?
- Cryptococcus
- H pylori
- Proteus
- Ureaplasma
- Nocardia
- Klebsiella
- Staph epidermidis
- Staph saprophyticus
Protein A: who has it and what does it do?
Staph aureus
- Binds to Fc portion of Ig, prevents opsonization and phagocytosis
IgA protease: who has it and what does it do?
- enzyme that cleaves IgA in hinge region, secreted by SHiN: s pneumo, h influ, neisseria
- used to colonize resp mucosa
M protein: who has it and what does it d?
- Group A strep
- prevents phagocytosis
How do ST and SLT from shigella and EHEC cause HUS?
their exotoxins: binding to 60S ribosome and enhances cytokine release
how do shigella and EHEC differ?
EHEC does not invade host cells
Genes for what 5 toxins can be encoded in a lysogenic phage?
ABCDE shigA like toxin Botulinum toxin Cholera toxin Diptheria toxin Erythrogenic toxin
which bugs are beta hemolytic?
- Staph aureus
- Strep pyogenes
- Strep agalactiae
- Listera monocytogenes
What is the MOA of exfoliative toxin?
- seen in staph aureus
- acts as a protease and cleaves desmoglenin desmosomes
How does staph epidermidis protect itself?
Producing adherent biofilms
how does vviridans group strep adhere to surfaces of teeth and valves?
- makes dextrans from glucose that aid organisms in colonizing = glycocalyx
rash that spares the face
scarlet fever
Which bacteria are hippurate test positive?
- Group B strep
- Gardnerella vaginosis
- Listeria
- Campylobacter
cytoplasm contains metachromatic granules hat stain with aniline dyes
Cornybacterium
What is the preformed toxin seen in bacillus cereus?
cereulide!
Which bug is able to multiply on cold enrichment culture?
Listeria
What is Fitz-Hugh Curtis syndrome?
infection of liver capsule from ascending infection
What factor does staph aureus provide w H influe?
factor V: niacin
When do you give rifampin prophylaxis?
H flu and meningococcal
Which bug’s antigen is preset in the urine?
Legionella
which bug has a grape like odor?
pseudomonas
What are E coli’s virulence factors and what do they cause?
- Fimbriae: cystitis and pyelonephritis
- K capsule: pneumonia and nonatal meningitis
- LPS endotoxin: septic shock
How do you distinguish EHEC 0157:H7 from other strains?
It doesnt ferment sorbitol
Where does salmonella typhii remain in carrier state?
in gallbladder
what happens when you give someone with salmonella antibiotics?
it prolongs the excretion in the stool
3 stages of Lyme disease?
Stage 1: erythema chronicum migrans, flu like sx
Stage 2: neurologic (facial n palsy) and AV nodal block
Stage 3: MSK, migratory polyarthrtitis and neurological (encephalopathy) and cutaneous manifestations
how does congenital syphillis transmission happen?
usually after the first trimester
False positives of VDRL?
Viruses- mono and hepatitis
Drugs
Rheumatic fever
Lupus and leprosy
Rickettsiae are obligate intracellular organisms that need what?
CoA and NAD+
cattle placenta
Coxiella burnetti
2 forms of chlamydia:
- Elementary body: small, dense, infectious, and enters cell via endocytosis
- Reticulate body: replicates in cell by fission , form seen in culture
Serotypes of Chlamydia and assoc disease:
ABC: chronic infection, cause blindness in Africa
D-K: urethritis/PID, ectopic pregnancy, neonatal diseases
L1, L2, L3: lymphogranuloma venereum
Systemic mycoses: ltretment for local vs systemic infections
Local: itraconazole or fluconazole
Systemic: ampho B
conidiophore with radiating chains of spores
Aspergillus fumigatus
How do Mucor and rhizopus cause infection?
- fungi proliferate in blood vessel walls when there is excess ketone and glucose, penetrate cribriform plate and enter brain
- has enzyme ketone reductase
trophozoites have RBCs in cytoplasm
entamoeba histolytica
flask shaped ulcer in submucosa of colon
entamoeba histolytica
cysts on acid fast stain
Cryptosporidium- severe diarrhea in AIDS
enterobius vermicularis
pinworm
strongyloides stercoralis
penetrates the skin- roundworm
what nematodes can cause iron deficiency anemia and how?
- Ancylostoma duodenale and Necator americanus: penetrate skin and suck blood from intestinal wall
onchocerca volvulus
- from female blackfly bite
- hyperpigmented skin and river blindness (black fly, black skin, black sight)
wuchereria bancrofti
- causes elaphantitis over 9 years bc of blocked lymphatics, transmitted by female mosquito
Loefflers eosinophilic pneumonitis
ascaris lumbricoides
cestode: ingestion of larvae encysted in undercooked pork or ingestion of eggs
Taenia solium
cestode: ingestion of larvae from raw freshwater fish, bug and disease?
Diphyllobothrium latum- vitamin B12 deficiency -> anemia
cestode: ingestion of eggs from dog feces
echinococcus granulosus (surgeons preinject cysts in liver with ethanol to kill bc could cause anaphylaxis)
fluke: snails are host, cercarieae penetrate skin
Schistosoma, liver and spleen granlomas leading to protal hypertension and splenomegaly
Fluke: undercooked fish, assoc with cholangiocarcinoma
clonorchis sinesis
Fluke: undercooked crab meat
paragonimus westermani
What two worms are associated with cancers?
- Schistosoma: squamous cell carcinoma of bladder
2. Clonorchis: cholangiocarcinoma
Parasite: brain cysts, seizures: bug and transmission
taenia solium, ingestion of eggs
Parasite: liver cysts, bug and transmission
Echinococcus granulosus, ingestion of eggs from dog feces
Parasite: vit B12 deficiency, bug and transmission
Diphyllobothrim latum, ingestion of larvae from raw freshwater fish
Parasite: biliary tract disease, cholangiocarcinoma, bug and transmission
clonorchis sinensis, undercooked fish
Parasite: hemptysis, bug and transmission
paragonimus westermani, undercooked crab meat
Parasite: portal hypertension, bug and transmission
schsitosoma mansoni, snails are host- penetrate skin
parasite: hematuria and bladder cancer, bug and transmission
Schistosoma haematobium, snails are host, penetrates skin
parasite: Microcycit anemia: bug and transmission
Ancylostoma, Necator
Parasite: perianal pruiritus, bug and transmission
Enterobius, fecal oral
Viral reassortment- who can do it and why is it improtant
- Segmented viruses only
- BOAR: bunya, orthamyxo, arena, reovirus
- the reason for genetic shifts -> pandemics
Live attenuated viruses?
- Smallpox
- Yellow fever
- Chicken pox/ Shingles
- Sabins polio
- MMR
- Influenza- intranasal
type of immunity w:
- Live
- Killed/inactivated
Live = cell and humoral
Killed: humoral only
Killed viruses
- Rabies
- Influenza (injected)
- Salk Polio
- HAV vaccine
Recombinant vaccines - 2
HPV and HBV
Which virus is not a retrovirus but carries its own reverse transcriptase?
HBV
what is exanthem subitum and who causes it?
another name for roseola- HHV-6
high fevers for several days followed by a diffuse macular rash
HHV-6 = roseola
Picornaviruses and assoc disease
- PERCH: polio, echo, rhino, coxsackie, HAV
- all can casue aseptic meningitis except HAV and rhino
- all are enteroviruses (fecal oral) except rhino
All paramyxoviruses contain what?
- surface F protein which causes respiratory epithelial cels to fuse and form multinucleated cells
Palivizumab
- monoclonal antibody against F protein in paramyxoviruses
- prevents pneumonia caused by RSV infection in premature infants
3 C’s of measles
cough coryza conjunctivitis
Where do you find rabies virus?
Purkinje cells of cerebellum
hydrophobia
rabies!
How do you treaet HCV?
Alpha interferon and Ribaviron
What ratio of CD4:CD8 determines AIDS?
<1.5
Why is an ELISA typically falsely positive in babies born to infectd mothers?
Anti-gp120 crosses the placenta
Where does HIV virus replicate in latent phase?
lymph nodes
superficial vascular proliferation in AIDS pt, non neoplastic, see neutrophilic infiltration
Bartonella henselae- bacillary angiomatosis
chronic watery diarrhea in AIDS patient
Cryptosporidium
Neoplastic superficial proliferation of vasculature, see lymphocytic infilatration
HHV-8, causing Kaposis sarcoma
source of food poisoning of vibrio vulnificus food poisoning
Contaminated seafood
What bugs cause osteomyelitis in IV drug users and diabetics?
Pseudomonas and Serratia
+ leukocyte esterase test in uti
bacterial cause
+ nitrite test in uti
gram negative
+ urease test in uti
proteus or klebsiella
- urease test in uti
e coli or enterococcus
How does rubella manifest in baby?
Triad of 1. PDA 2. Cataracts 3. Deafness \+/- blueberry muffin rash
How does CMV appear in baby?
blueberry muffin rash, hearing loss, seizures
baby born with hemorrhagic rhinitis
syphilis
what are the ToRCHeS infections?
Toxoplasma Rubella CMV HIV HSV-2 Syphilis
Baby of an IV drug user presents with oral thrush, interstitial pneumonia and secere lymphopenia
HIV-1 vertical transmission
What is malignant otitis externa?
- a severe infection most commonly seen in elderly diabetic patients
- caused by Pseudomonas aeruginosa
- present with excruciating ear pain and drainage
What vitamin shouldnt a pt on Levodopa take and why?
Vitamin B6- bc it increaes the peripheral metabolism of levodopa and decreases its effectiveness
What drugs can cause serotonin syndrome?
- Antidepressants: SSRIs, SNRIs, MAO, TCA
- Tramadol
- 5-HT3 receptor antagonists
- Linezolid
- Triptans
Where is the lowest pH found along the nephron?
the distal tubules and collecting ducts- whythe reason why uric acid recipitates here
What does CD95 do?
its the Fas ligand that activates extrinsic apoptotic pathway
what activates the caspases?
Ca influx!
Pale infarcts occur in what types of tissue?
heart
kidney
spleen
What are the acute phase inflammatory cytokines?
IL-1, IL-6 and TNFalpha- they signal endothelial cells to put out selectins to attract neutrophils!
Vasodilation and increased vascular permeability in acute inflammation is due to…
serotonin, histamine, and bradykinin
requires Vitamin C
What are metalloproteinases?
remodel after inflammation, require zinc
what is the result of chronic iron poisoning?
metabolic acidosis
what is dialysis related Amyloidosis?
- fibrils composed of Beta2-microglobulin
- in pt with ESRD or dialysis
- presents as carpal tunnel syndrome and joint issues
what is the gene mutation in hereditary Amyloidosis?
transthyretin (prealbumin)
amyloid deposits seen in DBM and Medullary thyroid CA?
DBM type II: Amyloid
Med thyroid: Calcitonin
which drugs follow a zero order elimination?
phenytoin
aspirin
alcohol
