Micro Bacterial pneumonia 2

Question 1

legionella bacteriology

Answer 1

• poorly staining gram -
• facultative intracellular parasite (free-living motile with flagella infectious and intracellular nonmotile during replication)
• accidental opportunistic (recently)

Question 2

transmission of legionella

Answer 2

biofilms in stagnant freshwater and in HVAC systems where tehy enter human lungs and parasitize alveolar macrophages

Question 3

is legionella contagious?

Answer 3

no - simultaneously exposed cases

Question 4

possible outcomes after contaminated water with legionella is inhaled or aspirated

Answer 4

asymptomatic seroconversion, pontiac fever, legionnaires disease

Question 5

pontiac fever

Answer 5

flulike, symptoms immunogenic as immune system kills live and/or clear dead bacteria
-patient is previously healthy

Question 6

legionnaires disease

Answer 6

• previously ill patient (elderly, immunosuppressed, diabetic, heart or lung disorder, smoking, alcohol)
• pneumonia with KIDNEY involvement and diarrhea

Question 7

legionella virulence factors

Answer 7

• dot/icm locus (type IV secretion system)
• pilE and pilD (pilus formation for attachment)
• pep/pro (zinc metalloprotease to escape)

Question 8

what are the symptoms or legionnaires disease due to?

Answer 8

infection and killing of alveolar macrophages (which engulf the bacteria but lysosomes fail to fuse with the resulting endosomes - bacteria then multiply and kill host cell)and renal failure

Question 9

risk factors for legionnaires disease

Answer 9

increasing age, immunosuppression, smoking, chronic heart/lung disease, chronic swallowing disorder, male

Question 10

presentation of legionnaires disease

Answer 10

altered mental status, headache, high fever, pneumonia/chest pain, acute renal failure, pancreatitis, diarrhea
clue is diarrhea and pneumonia together**

Question 11

diagnosis of legionella infection

Answer 11

-urine antigen test (commercial ELISA kit) - detects LP1 strain
does NOT detect other strains
-culture (difficult)
-silver stained biopsy (gram stain will fail)

Question 12

treatment of legionella

Answer 12

• pontiac fever resolves without treatment

- LD = antibiotic that penetrates infected cells (levofloxacin and azithromycin)

Question 13

complications for legionnaires disease

Answer 13

can have fatigue, neurological symptoms, neuromuscular symptoms, cough - usually takes a year to recover

Question 14

coxiella burnetii bacteriology

Answer 14

Q fever

-proteobacteria (related to legionella - used to be considered rickettsia)

Question 15

how is coxiella burnetii transmitted

Answer 15

inhalation of aerosols of infected urine, feces, birthing matter (no vector!)

• dander from infected animals is extremely infectious
• zoonosis of asymptomatic infection of ruminants

Question 16

where is coxiella burnetii common?

Answer 16

Q fever - common in netherlands, france, spain, iraq

Question 17

c. burnetii virulence factors

Answer 17

1. acid phosphatase

2. superoxide dismutase (helps bacteria survive in FUSED lysosome-endosome)

Question 18

pathogenesis of c. burnetii

Answer 18

multiples iwthin aveolar monocytes and macrophages - travels in them to liver, spleen, bone marrow (not just lung)

Question 19

presentation of c. burnetii

Answer 19

PNEUMONIA AND HEPATITIS also fever, chills, sweats, severe headache, dry cough, history of travel, pregnancy complications

Question 20

c. burnetti diagnosis, treatment, prevention

Answer 20

lab: IF, IHC, ELISA available
treatment: doxycycline or fluoroquinolones
prevention: vaccine available

Question 21

mycoplasma pneumoniae bacteriology

Answer 21

• smallest free living organism
• strictly aerobic
• no cell wall
• contains cholesterol in cell membrane
• fried egg shape in colonies

Question 22

what does mycoplasma pneumoniae cause in humans?

Answer 22

tracheobronchitis, bronchiolitis, atypical pneumonia “WALKING PNEUMONIA”

Question 23

how is mycoplasma pneumoniae transmitted?

Answer 23

respiratory droplets - resides on mucosal surfaces of respiratory and genital tract

Question 24

mycoplasma pathogenesis

Answer 24

• P1 adhesin binds respiratory epithelial cells
• some intracellular penetration
• CARDS exotoxin (ciliostasis, some cell death)
• also has hydrogen peroxide causing tissue damage - from bacterial metabolism

Question 25

what causes ciliostasis in mycoplasma? what is ciliostasis?

Answer 25

CARDS exotoxin

it is dry cough that exacerbates bronchitis, asthma due to inhibition of ciliary motion

Question 26

what do antibodies against mycoplasma cause?

Answer 26

cross reaction with RBC membranes (“cold-agglutinins”) - causes anemia that resolves spontaneously with disease

Question 27

mycoplasma exam

Answer 27

• more prevalent in winter
• MC pneumonia in young adults (NOT opportunistic)
• slow onset: nonproductive cough, sore throat, earache, small amounts of whitish sputum, fever, headache, malaise, mylagias
• chest Xray has rpominent infiltrates (looks worse than it is)

Question 28

lab for mycoplasma pneumonaiae

Answer 28

• not usually required - self-limited
• slow to culture
• cold agglutinins can detect RBC autoantibodies

Question 29

treatment of mycoplasma

Answer 29

-antibiotics reduce duration (disease will resolve spontaneously)