Ch 8 Flashcards
Non DNA containing organisms (class)
Prions
What is the difference btw gram pos vs neg in cell membrane?
Gram pos: one phospholipid layer (neg has 2)
What colour do gram negative bacteria take?
Red
What is a general rule regarding gram stain and shape of bacteria
Most bacilli are gram negative
Most cocci and gram positive
Therefore gram negative cocci - Neisseria
Gram positive bacillus - Corny Mike’s List of Basic Cars
What are the gram positive rods/bacilli
Corney Mike’s list of basic cats
Corney bacterium
Mycobacteria
Listeria
Bacillus
Nocardia
Endotoxins are exclusively secreted by which gram bacteria
Gram negative
What test detects viral load?
Polymerase chain reaction PCR
Chlamydiae forms ____ (shape) in its infectious form
Elementary body
Best test to diagnose mycobacteria/Nocardia?
Acid-fast stain
Silver stain is used to diagnose 3
Fungi
Legionella
P. Jirovecii
Mucicarmine is used to DX 1
Cryptococcus
Giemsa stain is used to diagnose 3
Parasites: Campylobacter, leishmania, malaria
What is the most common opportunistic pathogen infecting CNS in AIDS patients?
Toxoplasmosis
Toxoplasma causes (side) chorioretinitis in newborn
Unilateral
Diagnosis of toxoplasmosis?
Serology mainly
BX of affected tissues may show tachyzoites
What is Chagas Disease?
Caused by Trypanosoma Cruzi. Mainly effects heart (sudden death/arrythmia)
How does T. Cruzi invade host?
Through skin or mucous membranes transmitted by triatomine bugs
What is the metabolically active form of C. Trachomatis?
Reticulate body
Syphilis is caused by (organism)
T Pallidum
What mechanism allows T Pallidum to persist against host defense’s?
Outer membrane has TprK allows recombination with TprK gene: antigenic diversity
What is the main immune response in Syphilis?
T cells CD4+, Th1
How does Syphillic chancre spread?
Lymphatics and/or hematogenous
What is primary syphillis?
3 weeks post infection
Development of raised lesion (chancre)
What is secondary syphilis?
Occurs 2-10 weeks after chancre
1.Development of painless superficial lesions to skin and mucosa (palms, soles)
2. Fever
3. Lymphadenopathy
4. Neurosyphilis
Diagnosis of syphillis 2
Serology: cardiolipin- cholesterol-lecithin antigen (via Rapid Plasma Reagin,
VDRL tests)
Treponemal test: best for late/tertiary syphillis
Treponemal and non treponemal: for secondary and primary
What is tertiary syphillis?
- Cardiovascular (aortitis)
- Neurosyphilis
- Gummas in bone, skin, mucous membranes
What is benign tertiary syphillis?
Gummas forming in bone, skin, mucous membranes
What is congenital syphillis types? Sx
- Infantile: first 2 yrs of life. Nasal discharge in first few months.
- Tardive: desquamating bullous rash, hands and feet, mouth, hepatomegaly, skeletal.
Herpes blister
Skin
Secondary syphillis in dermis (endothelial proliferation, lymphoplasmacytic infiltrate)
What is unique about schistosoma infecting through skin?
Can dissolve adhesive proteins which hold keratinocytes together. Infection through unbroken skin
What are the characteristics of skin that can defend against microbes 4
Physical barrier
Fatty acids
Low PH
Defensins - small peptides toxic to bacteria
Which organism infects neutropenic patients?
Aspergillus sp
Which infection is opportunistic in AIDS?
P. Jirovecii
What immunoglobulin is secreted in stomach? Source?
IgA - Peyer’s patches
Which Candida causes oral thrush?
Candida albicans
Which infections can impair lung ciliary activity? 2
Bortadella pertussis
M. Pneumonia
Which infections can be transmitted through breast milk?
CMV
HIV
Hep B
How does influenza evade immune system?
Antigenic switching - has RNA segments that can recombinate
What does S. Pneumonia release to prevent phagocytosis?
Protein A - binds Fc portion of ab. Ab cannot bind to phagocyte receptors
How do some organisms resist cytokines/chemokines?
Release homologues IFN A/B/G to act as decoys; inhibition of JAK/STAT pathway or produce proteins that inhibit PKR (Protein kinase R)
What does IFN for viruses?
Inhibits viral replication
Which part of immune system does HIV infect?
CD4+ T cells
What is the mediator of ‘T cell exhaustion’?
Programmed cell death protein (PD-1)
What does PD-1 do immunity?
Maintains self tolerance to antigens
What is the mechanism of onset of rheumatic heart disease?
Streptococcal M protein antibodies cross reacts with cardiac protein
What infection are Burns patients at risk of?
P. Aureginosa
How does botulism cause paralysis?
A-B toxin inhibits synaptic release in neurons (does NOT kill neurons)
How does gram negative endotoxin LPS cause damage?
LPS binds to CD14 (LPS/CD14 complex). Complex then binds to TLR4
Lipoteichoic acid from gram positive bacteria bind to?
TLR2
E. Histolica: type of necrosis, organs affected
Colon and liver abscesses
Liquefactive necrosis
Which organism causes diarrhoea, and can invade liver (abscess)?
Entamoeba histolyca
What symptom does giardia cause?
Watery diarrhea
Symptoms of typhoid?
Splenomegaly (no hepatomegaly or abscesses)
What is the characteristic finding in scrapings of primary syphillis (Treponema)?
Obliterative endaritis with perivascular lymphocytes and plasma cells
Gummatous inflammation is seen in which types of syphillis?
Tertiary or congenital
Which common infection binds to ICAM-1?
Rhinovirus
What is cystecerosis?
Caused by taenia solium
Eating raw pork
Penetrate gut into brain - cysts
How does polio spread?
Fecal oral
How does polio cause paralysis?
Invades from mouth to anterior horn cells bulbar nuclei
What are the symptoms of Leishmania donovani? Places?
Middle East, Africa or South Asia, Latin America
Hepatosplenomegaly
Lymphadenopathy
Hyperpigmentation of skin
Pancytopenia
What does Leishmania invade (immune cells)?
Macrophages
Seen in HIV patient. DX?
CMV infection (Cytoplasmic inclusions)
Shigellosis vs Histolytica colonic ulcers?
Shigellosis in superficial (does not invade lamina propria)
Organism involved with colonic ulcers and development of Reiters in HLA 27 positive people?
Shigella flexneri
Presentation of C.Diphteria infection 3
Inflammatory membrane (tonsils, larynx)
Myocarditis
Neuropathy
What is Rocky mountain spotted fever?
Rickettsia
Vasculitis type rashes (trunk, palms/soles), thrombosis, necrosis of skin
From ticks
Organism associated with skin anaesthesia?
M. Leprae
Klebsiella is known for which complication?
Abscess formation
Bronchopneumonia and abscess formation is characteristic of which infection?
Actinomyces israeli
Falciparum: how does it invade?
Hepatocytes: cells rupture and merozoites invade RBC
What is the presentation of S.hematobium infection?
Affects bladder (calcifications, granulomas)
Africa
Mycoplasma pneumoniae: cause of lung haziness on XR?
Mononuclear infiltrates (monocytes, histiocytes)
Mechanism of Clostridium tetany causing muscle spasms?
Cleavage of synaptobrevin in synaptic vesicles of neurons
Subcutaneous crepitus associated with open wounds is usually caused by
Clostridium perferingence (gas gangrene)
Organism?
Trypanosoma
Coin lesions in lung caused by bird shit is caused by
H capsulatum
Patient has diabetic ketoacidosis, develops facial pain and eye proptosis
Mucor sp
What is the presentation of rotavirus?
Toddler <6 months
Diarrhea
Villous atrophy: cannot absorb sodium/water
How does granuloma formation kill microbes?
Macrophages secrete nitric oxide
Fever and haemolytic anaemia. RBC looks like this. DX?
Babesia
What are the 3 types of chlamydia?
Primary
Secondary
Late
What does primary chlamydia symptoms?
Small painless ulcer that heals
What does secondary chlamydia present like?
Painful lymphadenopathy, rectal ulcers
What does chlamydia at late stage present like?
Anogenital strictures and fibrosis
Colon. DX?
Entamoeba histolyca ‘flask shaped’ ulcer
How does Rickettsia spread?
Vector borne
What makes older kids resistant to rotavirus?
IgA
What is the presentation of congenital syphillis?
Still birth, hydrops
Saber shins, saddle nose, Hutchinson’s teeth
Diffuse rash
Lungs pale
Periosteitis, osteochondritis of femur/vertebrae
Which cranial nerve is affected in congenital syphillis?
CN VIII
How does Dengue haemorrhagic shock happen?
Previously infected person, gets reinfected
What are the seudomonas virulence factors? 4
Exotoxin A
Exotoxin S
Phospholipase C
Fe compounds
Pseudomonas: what effect does exotoxin A have?
Inhibits protein synthesis
Pseudomonas: what effect does exotoxin S do?
Inhibits host cell growth
Pseudomonas: what effect does phospholipase C do?
Degrades pulmonary surfactant
Where does schistosoma lay in body? Effects on presentation?
Hepatic venules –>fibrosis–>portal HTN
Presentation of Nocardia?
Contact with soil
Pneumonia–>brain, kidney, skin
Immunocompromised host
What is an agglutination test?
Small particles (eg bacterial) are coupled with a reagent antibody/antigen. This is added to patient sample: agglutination will occur if target antibody/antigen/bacterial is present
Agglutination of 32. Meaning?
The most dilute sample giving agglutination is 1/32 of initial
What is complement fixation?
Diagnosis for fungal, viral infections (esp cocciodiomycosis)
Incubate specimen with known amounts of complement and antigen - degree of fixation
Measures IgM or IgG
Labour intensive, controls
Which test is used for fungal or pyogenic meningitis?
Precipitation tets
What is PCR?
Test that creates polymers of DNA and replicates them
What polymerase is used in PCR?
TAQ polymerase
What are the steps in PCR?
1.Denaturation (high temp to separate DNA)
2.Annealing (cooling so primers can bind to DNA)
3.Extension (synthesis of new stands)
How to check that correct products are made through PCR?
Agarose gel electrophoresis
What is the key concept of flow cytometry?
Hydrodynamic focusing