Clinical Infectious Disease Flashcards
List human barriers to infection
- skin and mucosa
- secretory/excretory
==> lysozymes in tears
==> stomach acid - commensal flora
Describe mechanisms of bacteria-induced injury.
- bacterial virulence (adhesion, invasion, toxin)
- bacterial adherence
==> adhesins on bacterial surface bind to host molecules
==> entry into macrophages (via antibodies or complement)
==> entry into epithelial cells (surface markers, integrins) - bacterial endotoxin
==> LPS on gram negative induces cytokine response leading to fever and T/B-cell activation - bacterial exotoxin
==> diphtheria, cholera, anthrax
==> allows growth of bacteria
Identify microbial pathogens that exhibit significant antigenic variations.
- rhinovirus
- influenza
- neissaria gonorrhea
- borellia hemsii (relapsing fever)
- borrelia burgdorferi (lyme disease)
- trypanosoma brucei (african sleeping sickness)
- giardia lamblia
- plasmodium falciparum (severe malaria)
Describe 3 classes of helminths and give an example of each.
ROUNDWORMS: collagenous tegument, nonsegmented
- nematodes (hookworms)
FLATWORMS: gutless, ribbon-like, segmented
- cestodes (tapeworms)
FLUKES:
- trematodes (schistosomes)
Describe the following characteristics of viruses:
- size
- site of propagation
- composition
- sample species and diseases
- general disease
SIZE: 20-30nm; smallest
SITE: obligate intracellular
SAMPLE
- poliovirus => polio
COMPOSITION
- composed of capsid/coat and nucleic acid core (DNA/RNA)
- rely on host genetic machinery for replication
GENERAL DISEASE
- cause acute (colds) or latent infections (shingles)
Describe the following characteristics of chlamydiae:
- site of propagation
- sample species and diseases
- general diseases
SIZE: 200-100nm SITE: obligate intracellular SAMPLE -chlamydia trachomatis => trachoma GENERAL DISEASE - cause GU infections, conjunctivitis, respiratory infections and STDS
Describe the following characteristics of rickettsiae:
- site of propagation
- sample species and diseases
- mode of transmission
- general diseases
SIZE: 300-1200 nm SITE: obligate intracellular SAMPLE - rickettsia prowazekii => typhus fever TRANSMISSION: insect vectors (ticks, lice, mites) GENERAL DISEASES - rocky mountain spotted fever - erhlichiosis
List the 3 microorganisms that are obligate intracellulars.
- viruses
- chlamydiae
- rickettsiae
- some forms of protozoa (leishmania)
Describe the following characteristics of mycoplasmas:
- site of propagation
- sample species and diseases
- general diseases
- fun fact
SITE: extracellular SAMPLE - mycoplasma pneumoniae => atypical pneumoniae GENERAL DISEASE - atypical pneumoniae - nongonococcal urethritis FUN FACT: tiniest free living organisms
Describe the following characteristics of bacteria, spirochetes, mycobacteria:
- site of propagation
- sample species and diseases
CUTANEOUS - staphylococcus epidermis => wound infection MUCOSAL - vibrio cholera => cholera EXTRACELLULAR - streptococcus pneumoniae => pneumonia FACULTATIVE INTRACELLULAR - mycobacterium tuberculosis => TB
Describe the following characteristics of fungi imperfecti:
- site of propagation
- sample species and diseases
- growth patterns
- general diseases
CUTANEOUS - trichophyton sp. => tinea pedia MUCOSAL - candida albicans => thrush EXTRACELLULAR - sporothrix schenckii => sporotrichosis FACULTATIVE INTRACELLULAR - histplasma capsulatum => histoplasmosis
GROWTH PATTERNS
- budding yeast
- hyphae => slender tubes/branches
- conidia => fruiting bodies on the ends of hyphae
GENERAL DISEASE - typically infect superficial layers of skin
- deep infections can spread
- opportunistic infections that normally colonize body can cause disease in immunosuppressed
Describe the following characteristics of protozoa:
- site of propagation
- sample species and diseases
- composition
- modes of transmission
MUCOSAL - giardia lamblia => giardia EXTRACELLULAR - trypanosoma gambiense => sleeping sickness FACULTATIVE INTRACELLULAR - trypanosoma cruzi => chagas disease OBLIGATE INTRACELLULAR - leishmania donovani => kala-azar
COMPOSITION
- parasitic
- motility, pliable plasma membrane
- complex cytoplasmic organelles
MODES OF TRANSMISSION
- sexual (trichomonas)
- fecal oral (giardia)
- insect vectors (leishmania)
- infected cats/undercooked meats (toxoplasma)
Describe the following characteristics of helminths:
- site of propagation
- sample species and diseases
- reproduction
- general disease
MUCOSAL - enterobius vermicularis => oxyuriasis EXTRACELLULAR - wuchereria bancrofti => filariasis INTRACELLULAR - trichinella spiralis => trichinosis
REPRO: most are dependent on host or vector for asexual reproduction
GENERAL DZ: caused by eosinophilic inflammatory response in proportion to number of infecting organisms
List microorganisms that can be facultative intracellular.
protozoa
fungi
bacteria
List microorganisms that can be extracellular.
bacteria fungi bacteria mycoplasmas protozoa helminths
List microorganisms in order of size.
virus chlamydiae rickettsiae mycoplasma bacteria, spirochetes, mycobacteria fungi protozoa helminths
List microorganisms that propagate in mucosal.
bacteria
fungi
protozoa helminths
List microorganisms that propagate in cutaneous.
fungi
bacteria
Describe the following characteristics of prions:
- composed of?
- pathogenesis
- associated diseases.
- composed of modified host prions (acellular)
- causes transmissible spongiform encephalitis
- diseases: mad cow, kuru, Creutzfeld-Jakob Disease (CJD)
Define bacteriophage. What are some associated diseases?
- virus that has infected bacteria; becomes part of the bacterial genome
- can input adhesins, toxins, enzymes to confer antibiotic resistance
- diseases: cholera is due to toxin genes of bacteriophage
Describe bacteria. Distinguish gram negative and gram positive bacteria.
- prokaryotes that lack ER and nuclei
- rely on host for favorable replicative conditions
- can grow extra- and intra-cellularly
- gram negative: rigid cell walls with inner and outer phospholipid membranes
- gram positive: single inner membrane with rigid cell wall
Characterize chlamydiae, rickettsiae, and mycoplasmas.
- obligate intracellular
- divide by binary fission
- susceptible to antibiotics, but lack certain cell structures
=> ex: mycoplasmas lack cell wall (peptidoglycan)
Describe ectoparasites.
- arthropods (ticks, lice, bedbugs, fleas)
- attach and live on skin
- vectors for other pathogens (ex: lyme disease)
List modes of transmission.
- contact
- aerosol
- saliva
- sexual transmission
- open airway
- fecal oral
- water borne
- insects to skin
- skin => insects => skin
- zoonotic (reservoir host)
- placental fetal
Describe mechanisms of immune evasion by microorganisms.
- inaccessible (intracellular)
- resistant to complement and phagocytosis
- varying or shedding antigens
- immunosuppression
List the 5 types of inflammatory response to infection and an example of a microorganism that causes each.
- suppurative (PMN) ex: pneumococcal pneumonia
- mononuclear (granulomatous) ex: syphilis chancres
- cytopathic/cytoproliferative inflammation ex: HPV, herpesvirus, measles, CMV
- necrotizing inflammation (group A streptococcus)
- chronic inflammation and scarring (schistosome eggs)
Describe suppurative inflammation.
- caused by pyogenic bacteria
- increased vascular permeability, neutrophil infiltration
- neutrophil recruitment via:
=> directly by release of chemoattractants
=> indirectly by endotoxin that stimulates macrophages to release cytokines
Describe mononuclear and granulomatous inflammation.
- diffuse, mononuclear infiltration
- includes lymphocytes and macrophages depending on pathogen
Describe cytopathic/cytoproliferative inflammation.
- virus-mediated damage to host cells in the absence of host inflammatory response
characteristics: - inclusion bodies (CMV)
- polykaryons following cell fusion (measles)
- blisters (herpesvirus)
- lesions (HPV)
- dysplasia/cancer
Describe necrotizing inflammation.
- rapid, severe tissue damage
- cell death
- due to uncontrolled viral infections, bacterial toxins, or protozoa-mediated cytolysis of host cells
- ex: necrotizing fasciitis by group A streptococcus
Describe chronic inflammation and scarring.
due to inert organisms
- schistosome eggs
