LRT Bacteria

Question 0

Streptococcus pneumoniae

Answer 0

LRT bac
-*Gr+, cocus, short paired chains (lancet-shaped)
-"pneumococcus"
-*rust color sputum
-normal microbiota oro-nasopharynx
-*alpha-hemolytic
-*bile soluble
-*optochin sensitive
Virulence
-*polysaccharide capsule
-*IgA1 protease
-*pneumolysin
-*phosphocholine in CW=C polysaccharide
Diagnostic
-*Quellung rx+

Question 1

Bortella pertussis

Answer 1

LRT bac
-small, Gr- coccobacillus
-causes whooping cough
Virulence
-filamentous hemagglutinin (FHA)
-*tracheal cytotoxin
-*pertussis toxin
  -AB exotoxin (*lymphocytosis)
-toxins enter cells, bloodstream
-*respiratory droplets (extremely contagious/tropism for ciliated bronchial epithelium)(*destroys cilia)
Diagnostic
-fastidious
-*Bordet-Gengou agar
-*Regan-Lowe agar
-*marked lymphocytosis (up to 70% lymph)
-*culture (gold standard) on nasopharygeal specimen
-*PCR

Question 2

Haemophilus influenzae

Answer 2

LRT bac
-Gr-, coccobacillus
-normal microbacteria URT
-6 types (a-f), type b (*Hib) strains cause invasive disease
-*nontypeable strains are *unencapsulted (cause pneumonia)
-*major cause of epiglottitis
Virulence
-*Hib is capsular type (*PRP)
-*LPS
-*IgA1 protease
-pili
Diagnostic
-*chocolate agar
-requires growth factors *hemin (X-factor) and *nicotinamide adenine nucleotide (V-factor)
-*Quellung rx+

Question 3

Bacillus anthracis

Answer 3

LRT bac
-large, Gr+ rod w/ square ends, single, pairs, *chains
-in soil, vegetation
-often occupational (wool, hair, hides)
-*bioweapon
-*aerobe to facultative anaerobe
-*pulmonary anthrax=inhalation anthrax=Woolsorter's disease
Virulence
-*endospores
-*protein capsule (*poly-D-glutamate)
-*survives and replicates in MACs
-*AB exotoxin complex
-*LF=Zn-dependent metalloprotease
Diagnostic
-CXR=**mediastinal widening

Question 4

Mycoplasma

Answer 4

LRT bac
-smallest free-living prokaryotes
-normal microbiota in mouth, GU
-*tiny "fried egg" colonies
-*lack CW-->*pleomorphic
-*CW contains *sterols
-causes *persistent, hacking cough
-*atypical pneumonia
Virulence
-P1 adhesin
Diagnostic
-not visible on gram stain
-*cold agglutinins=IgM atb

Question 5

Chlamydophila pneumoniae

Chlamydophila psittaci

Answer 5

LRT bac

• small Gr-
• *lack peptidoglycan
• *obligate intracellular parasite
• *various cell types (lung epithelium, MACs, vascular endothelium)
• C. pneumonia animal, human pathogen
• C. psittaci bird pathogen (*zoonotic pneumonia ornithosis)
• life cycle alternates from *elementary body (extracellular form-inactive, infectious) to *reticulate body (replicating form

Question 6

Legionella pneumophila

Answer 6

LRT bac
-small, pleomorphic Gr- rod
-found in lakes, streams, air conditioners, water-cooling towers, shower heads, taps, hot tubs, misters
-causes CAP and HAP
-facultative intracellular (in MACs)
-legionellosis pneumonia (severe!) vs. pontiac fever
Virulence
-biofilms
-proteases, phosphatases, lipases, nucleases
Diagnostic
-fastidious, requires buffered charcoal yeast agar (BCYE) w/ cysteine and iron
-CYPE
-urine antigen tests
-stains poorly (silver stain common)