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bacteria and viruses Flashcards

1
Q

Non-obligate intracellular parasites

A

Mycobacteria, Mycoplasma, and Spirochetes

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2
Q

Mycobacterium tuberculosis

world incidence 1/4 of pop-> highest cause of mortality worldwide

A

Transmission:
obligate aerobic rods
ACID FAST STAINING
Lung is main infection

History:
exposure-> 70-90% not infected, 10-30% infected-> latent 90% and active 10% = reactivation disease-> then die

Patho: SURVIVES WITHIN PHAGOSOMES OF MACROPHAGES-> protein prevents fusing with lysosome so escapes degradation
2 types of lesions:
1. Exudative/active lesions= draining nodes= Ghon complex
2. Latent area of caseating necrosis walled off by tubercle (firbous tissue)= Granulomas

PRIMARY LESIONS IN LOWER LOBES & REACTIVATION LESIONS IN APICES

Spread:
1. tubercle erodes into bronchus-> empties caseous contents
2. Disseminates via bloodstream

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3
Q

Clinical presentation of tb

A

Primary tuberculosis:
* CNS- appetite loss and fatigue
* Lungs- coughin up blood, productive prolonged cough
* Skin- NIGHT SWEATS

Extrapulmonary tuberculosis:
* scrofula
* tuberculosis pleurisy
* pott’s disease in spine
* Urogenital tuberculosis

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4
Q

Immune response to Primary Tuberculosis

A
  1. Granuloma formation- fibrous calcification of tubercules
  2. Cellular immunity fight-> CD4 cells, IFN-Y, and Macrophages (AB present but not useful bc intracellular)

Positive PPD skin test- delayed hypersensitivity reaction

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5
Q

Interpretation of PPD

A

IFNY release assays = highest sensitivity/specificity
Bc induces macrophages to release

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6
Q

BCG V

A

Live attenuated M. bovis
DOES NOT PREVENT INFECTION BUT REDUCE SYMPTOMS

uses: countries iwth high incidence
RECOMMENDED FOR CHILDREN IN US THAT LIVE WITH SOMEONE WITH ACTIVE TB

Testing implications:
PPD positive for 2-3 mon but decrease w/ time
<10 mm at 10 yrs

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7
Q

Atypical Mycobacteria

MAK

A
  1. M. kansasii- tb like in immunocomp
  2. M. marinum- swimming pool granuloma
  3. M. avium-intracellulare complex- tb like in immunocomp
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8
Q

M. avium intracellulare complex

MAC

A

Pulmonary disease: Clinical syndromes
1. disease with known underlying lung disease WHITE, MIDDLE AGED MALE OFTEN SMOKERS AND ALCOHOL UNDERLYING copd OR CF PT
2. Disease without underlying lung disease- non smoking women >60 yrs who have nodules on cxr and no known lung

Less common: hot tub lung- hypersensitivity pneumonitis and MAC infxn with solitary pulmonary nodules resembling lung cancer

Disseminated disease: IMMUNOCOMPROMISED PTS
HIV, TNF ALPHA INHIBITORS

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9
Q

Mycoplasma pneumoniae

atypical pneumonia

A

walking pneumonia- human pathogen with respiratory droplet transmission

Clinical course: teens, young adults, college students
* Non specific prodrome- nonproductive cough, sore throat, earache
* Fever, headache, malaise, myalgia
* xray shows inflitrates but pulmonary exam unremarkable
assosciated w/ stevens johnson, raynauds, guillain barre, arrhythmia

can see hemolysis- and clinical signs of anemia

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10
Q

Spirochetes

A
  1. Treponema pallidum-> Syphilis
  2. Borrelia burgdorferi- lyme disease
  3. Borrelia recurrentis- relapsing fever
  4. L. interrogans- Leptospirosis
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11
Q

Syphilis

TORCH INFECTION

A
  • Hx: sexual contact
  • Primary: spirochetes multiply at site of inoculation-> chancre forms 2-10 wks later (nontender ulcer)-> spread via bloodstream-> enlarged regional lymphnodes
  • Darkfield microscopy = godl standard
  • Secondary: 1-3 months after
  • **generalized maculopapular rash- palms and soles
  • Condylomata lata-> moist papules on genitals and mimic warts/molluscum**
  • fever, malaise, anorexia, weight loss
  • Tertiary:
  • Aortitis, aneurysms, aortic regurgitation-> cns disorders

IM PENICILLIN G q week x3 weeks

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12
Q

Neurosyphilis

can b any tie in disease

A

Tabes dorsalis:
disease of posterior columns of spinal cord and dorsal roots-> sensory ataxia and stabbing pains
Argyll- Robertson pupils- not reactive to light and pain

syphilitic meningitis, meningovascular syphilis, ocular syphilis, otosyphilis

Labs: Positive CSF-VDRL
TX: IV Penicillin G

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13
Q

Lyme disease

Most common vector borne illness in US

A

Borrelia burgdorferi-> Ixodes tick
1. Early localized stage
* erythema migrans (macular erythematous target)
* flu like
* lymphadenopathy
* 40% resolve after this phase
2. Early disseminated stage
* neuro involvement-> aseptic meningitis, cranial neuropathy, motor/sensory radiculopathy
* Bells palsy
* Cardiace involvement-> variable AV blocks
* Multiple erythema migrans lesions
3. Late disseminated stage
* arthritis of large joints with visible swelling
* encephalopathy, encephalomyelitis

Testing:
1. Enzyme immunoassay or Immuno fluoro
2. IgM, IgG, western blot

TX:
prophylactic tx available but tx clinically

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14
Q

Obligate intracellular parasites

A
  1. chlamydia
  2. rickettsiae
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15
Q

Chlamydiae

clamydophila and clamydia

A
  1. Chlamydia trachomatis
    * Urethritis, pneumonia, conjunctiviis, lymphogranulom a vereum, trachoma
    * diag: NAAT
    * tx: doxycycline
  2. Chlamydophila pneumoniae
    * atypical pneumonia
    * diag: serologic testing
  3. Chlamydophila psittaci
    * psittacosis/pneumonia
    * birds carry
    * inhalation of dried bird feces
    * Diag: serologic test NAAT
    * tx: doxycycline
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16
Q

Chlamydia trachomatis

TAG

A
  1. Trachoma- chronic keratoconjunctivitis leads to eyelid scarring and blindness
  2. Genital tract infections STI- Neonatal conjunctivitis and lymphogranuloma venereum (genital papule, lymphadenopathy, from MSM)
  3. Autoimmune- Reactive arthritis and reiter’s syndrome
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17
Q

Reactive arthritis

Reiter’s syndrome

A
  1. Conjunctivitis
  2. Urethritis
  3. Arthritis

Cause:
Urogenital: chlamydia trachomatis
Enteric: Campylobacter, salmonella, shifella, yersinia

HLAB27 +

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18
Q

C. pneumoniae

chlamydia

A
  • bronchitis and pneumona in adolescents and young adults
  • cough, dyspnea, fever
  • Pharyngitis, laryngitis, sinusitis
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19
Q

Rickettsiae

A
  1. Rocky mountain spotted fever- rickettsia rickettsii-> ticks-> southeastern states
  2. Q fever-> cattle, sheep, goats
  3. Ehrlichiosis-> from ticks
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20
Q

Rocky Mountain spotted fever

A

SXS: fever, headache, myalgia, prostration-> later Rash (macules to petechiae from hands and feet towards trunk-> children in warm months in the southeastern US

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21
Q

Q fever

know this one

A

Agent: Coxiella
Reservoir: cattle, sheep, goats
Transmitted: inhalation of aerosolized animal waste
Progress: PNEUMONIA AND OR HEPATITIS
ranchers and shepherds

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22
Q

Ehrlichiosis

AAgent: Ag

A

Agent: Ehrlichia
Lymphopenia
thrombocytopenia
elevated LFTs
LONE STAR TICK

TESTING:
INDIRECT FLUORESCENT AB TEST

23
Q

Gram variable Odd balls

A
  1. Gardnerella vaginalis
  2. Actinomycetes
    * actinomyces israelii- dental infxn-> normal oral flora
    * nocardia asteroides- pneumonia, skin infxn, brian abscesses
24
Q

Gardnerella vaginalis

all bolded

A

Bacterial vaginosis-> due to shift in microfloral populations, replaced by gardner
SXS: white/gray colored discharge, fishy odor, subjective irritation but no inflamm changes

Labs: = whiff test
clue cells- fried egg with pepper

25
Actinomyces | a. israelii causes most infxn
Normal oral flora-> minor trauma hard nontender swelling that eventually drains
26
Nocardia asteroides
2 forms: Pulmonary-> acute bronchopneumonia Cutaneous-> skin trauma leads to cellulitis Disseminated to organs and to **brain abscess Immunocompromised at risk-> opportunistic infxn**
27
Summary
28
Viral general info
DNA or RNA obligate intracellular parasites with capsi surounding nucleic acid Envelope is a lipoprotein membrane that is virus specific outer proteins can be antigenic
29
Viral replication
Absorption= specific for host cell proteins Genome replicates using host machinery * dna virus-> replicate in nucleus * RNA -> replicate in cytoplasm Lysis vs exocytosis to escape
30
Fetal and Neonatal
TORCH- Toxoplasmosis, Other (syphilis), Rubella, cytomegalovirus, Herpes simplex 1. Transplacental- cytomegalovirus, rubella virus 2. Perinatal- Herpes simplex virus type 2 3. Breast feeding
31
viruses with animal reservoir | dont mem just understand
1. Rabies- skunks, raccoons, bats-> from bite 2. Hantavirus- deer mice 3. Encephalitis viruses- birds- bite from mosquitoes 4. Avian influenza- fowl- aerosol droplets
32
Viral pathogenesis
1. Death of infected cells-inhibition of macromolecule synth 2. Immunopathogenesis-killing of virus infected cell by cd8 tcells 3. Evasion of host defenses-altering ag
33
Persistent viral infections
1. Chronic carrier infection- infected and produce virus for a long time 2. latent infections-recovers and stops production 3. slow virus infections-prolonged period btwn initial infection and onset of disease
34
Nonspecific Host Defenses
1.Interferons 2.NK cells 3.Phargocytosis 4.Defensins 5.Apolipoprotein B RNA-editing enzyme 6.Fever 7.Mucociliary clearance Factors that modify defenses- extremes of age, increased corticosteroid levels, malnutrition ## Footnote all highlighted
35
Specific host defenses
Active immunity- CD8 and 4 Passive immunity- IgG and IgA Herd immunity- interrupts transmission
36
Lab tests
Culture Microscopic: Inclusions, MGCs (Tzanck smear), Fluorescent tests Serology: IgM, complement fixation Direct ag detection: ELIS Nucleic acid detection: PCR
37
Poxviruses
1. Smallpox (variola) 2. Cowpox (vaccinia) 3. Molluscum Contagiosum (only one we have to worry about)
38
Smallpox virus
eradicated in 1977 Transmission: respiratory aerosol- incubate in 1-2 wks SXS: sudden fever and malaise-> Centrifugal rash (more at edges Bioterrism-> ring vaccine within 4 days of exposure
39
Molluscum Contagiosum
Transmitted by close contact SXS: **round, flesh colored, waxy, umbilicated papule on skin or mucous membrane**, painless, nonpruritic immunosuppressed can get extensive infection can be mistaken for basal cell carcinoma
40
Human papillomavirus | DNA virus
SXS: **warts and carcinoma of cervix, penis, and anus** Transmission: skin to skin contact Incubation: 1-20 months Immunosuppressed pts have more warts and higher rates of cervical cancer ## Footnote HPV type 16 most highly indicated for cervical cancer
41
HPV Vaccines
Gardisil-quadrivalent- 1st gen Gardisil 9: nonavalent- 9 strains types: 16, 18, 31, 33, 45, 52, 58- 97% of cervical cancer Females 9-26 or males 9-15
42
Juvenile laryngeal papillomatosis
Transmission: infected mother to neonate during birth-> warts in mouth and resp tract of infant SXS: cough, pneumonia, HOARSENESS infancy or any age
43
Herpes viruses
1. HSV-1- Gingivostomatitis-> in ganglia-> recurrent infxn: herpes labialis, encephalitis, keratitis 2. HSV-2- Herpes genitalis, perinatal disseminated dx-> ganglia-> herpes genitalis 3. VZV- varicella (chickenpox)-> ganglia-> Zoster 4. EBV- infectious mononucleosis-> B LYMPHOCYTES 5. CMV- congenital infection, mononucleosis-> monocytes 6. HHV-6,7- Roseola-> lymphocytes 7. HHV-8- lymphadenopathy, fever, exanthema-> B cells-> Kaposi sarcoma
44
HSV1 VS HSV2
HSV1: * lesions above waste * gingivostomatitis in mouth * Keratoconjunctivitis eye * Encephalitis of temporal lobe * rare in neonates * can disseminate to viscera in immunocompromised pts HSV2: * below the waist * rare mouth * rare eye * Meningitis * Neonate skin lesions and disseminated infection * rare dissemination | incubation 2-10 days ## Footnote diag with PCR or Tzanck smear
45
HSV1
46
HSV2
Genitals and TORCH prego
47
Varicella-Zoster virus VZV
Varicella (chickenpox)- primary disease Zoster (shingles)- recurrent form infects mucosa of Upper resp tract then spreads to blood then sensory neurons to dorsal root ganglia -> latent
48
Varicella
* chickenpox * incub 14-21 days * brief prodrome of fever and malaise * teens/adults: varicella pneumonia | dew drop on rose petal
49
Varicella
* chickenpox * incub 14-21 days * brief prodrome of fever and malaise * teens/adults: varicella pneumonia | dew drop on rose petal
50
Zoster | shingles
latent infection reactivated -> dermatome vesicular rash immunocomp-> disseminated disease opthalmic herpes zoster
51
Ramsey-Hunt syndrome
* Herpes zoster oticus * facial nerve affected-> ipsilateral facial paralysis, ear pain, vesicles in auditory canal tx: antivirals and steroids-> same as BELLS PALSY
52
Epstein-Barr virus
Causes: Infectious mononucleosis SXS: Fever, pharyngitis, lymphadenopathy over a wk, splenomegaly Assoc w/: Burkitt lymphoma | No physical activity bc of burst spleen
53
Cytomeglovirus | MC infectious cause of congenital abnormalities ## Footnote LEADING CAUSE OF MENTAL RETARDATION
* MOST ARE ASYMPTOMATIC * heterophile negative monosyndrome- Fever, lethargy, abnormal lymphocytes in blood smear Immunocompromised: * systemic infxn- pneumonitis, esophagitis, hepatitis * AIDS PTS COMMONLY HAVE COLITIS WITH DIARRHEA-> RETINITIS THAT LEADS TO BLINDNESS Testing: PCR is a gold standard TX: Ganciclovir

Patho (4 decks)

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