Atypical Pneumonia - Chlamydia, Legionella, and Mycoplasma

Question 1

What is unique about Chlamydia’s life cycle?

Answer 1

It’s biphasic w/ two functionally and morphologically distinct forms

Question 2

What is chlamydia’s life cycle?

Answer 2

Elementary body (EB) enters cells - inhibits phagolysosomal fusion and becomes a reticulate body (RB). –> RB forms daughter EBs and they are released from the cells

Question 3

T or F. Chlamydia is an obligate intracellular parasite.

Answer 3

true - depends on host cell to provide numerous compounds

Question 4

Why is chlamydia not classified as a gram negative bacteria?

Answer 4

b/w the EB doesn’t have a peptidoglycan and muramic acid but peptidogylcan is involved in the cell cycle at some point

Question 5

What type of organism is Legionella?

Answer 5

gram negative rods, aerobic, nonencapsulated, facultative IC pathogens

Question 6

Describe mycoplasma!

Answer 6

the smallest free-living organism and lacks a cell wall. nutritional requirement for a sterol is unique among prokaryotes

Question 7

What is the major component of M. pneumonaie infection?

Answer 7

immunopathology. mycoplasma doesn’t enter nor penetrate the host cells. Instead it uses its lipoproteins to interact w/ TLRs on macrophages to produce cytokines

Question 8

What are the virulence factors for chlamydia?

Answer 8

Proteins involved in the Type 3 secretion system: Tarp, Pkn5, CopN, inclusion membrane proteins, lipoproteins (CdsJ)

Question 9

Where does Leiongella pneuophila replicate?

Answer 9

in alveolar macrophages after inhalation

Question 10

What is an important virulence determinant of L. pneumophila?

Answer 10

avoidance of phagosome-lysosome fusion in phagocytic cells

Question 11

How does legionella support bacterial replication?

Answer 11

bacterial proteins alter the vesicle traffic and a specialized vacuole forms that resembles the ER of the host.

Question 12

What do the virulence factors for Mycoplasma do?

Answer 12

production of bacterial, polarized, adhesin complex

Question 13

What diseases does Chlamydia cause?

Answer 13

1. Psittacosis (parrot fever)
2. Pneumonia
3. Ocular, respiratory, and genital tract infections

Question 14

Tell me about psittacosis!

Answer 14

caused by C. psittaci; birds = reservoir; spread by inhaling organisms in dried bird feces

Question 15

What percentage does Chlamydia pneumonaie account for CAP?

Answer 15

6-10%

Question 16

What other disease has C. pneumonaie infection been associated w/?

Answer 16

coronary heart disease

Question 17

What does Chlamydia Trachomatis cause?

Answer 17

ocular, respiratory, and genital tract infections

Question 18

What is the reservoir for chlamydia trachomatis?.

Answer 18

humans

Question 19

What cells do chlamydia trachomatis infect?

Answer 19

squamocolumnar cells of mucous membranes

Question 20

What is trachoma caused by and what it is?

Answer 20

immunotypes A-C and it’s an infection of the conjunctiva and the world’s leading preventable cause of blindness

Question 21

What immunotypes of C. trachomatis cause genital tract infections?

Answer 21

D-K, some of these serotypes are associated w/ cervical squamous cell carcinoma

Question 22

What is the most common sexually transmitted pathogen in industralized countries?

Answer 22

chlamydia trachomatis

Question 23

How can neonatal pneumonia and neonatal inclusion conjuctivits be prevented?

Answer 23

erythromycin eye drops at birth

Question 24

What is an unique problem of C. trachomatis infections?

Answer 24

50-70% in women are clinically silent

Question 25

Who are at risk for Legionnaires' disease?

Answer 25

elderly, ICP, heavy smokers, alcoholics, and other w/ compromised lungs. Males are over twice as susceptible as females

Question 26

What is Pontiac fever?

Answer 26

milder illness caused by L. pneumophila. Attacks 95% of those exposed indiscriminately and causes flu-like symptoms

Question 27

What diseases does Mycoplasma cause?

Answer 27

1. primary atypical pneumonia - mild respiratory infections characterized by sore throat and pharyngitis 2. nonspecific urethritis caused by ureaplasma urealyticum 3. postpartum fever and pelvic inflammatory disease caused by M. hominis

Question 28

What are the symptoms of C. pneumoniae?

Answer 28

most have relatively mild respiratory illness, symptoms of bronchitis or pneumonia. Scant sputum, prominent cough, history of hoarseness, headache, fever in early days, sinus percussion tenderness, rales and rhonchi

Question 29

What are the symptoms of Legionnaires disease?

Answer 29

high fever, chills, cough, muscle aches and headaches. Symptoms usually begin 2-14 days after being exposed to bacteria

Question 30

What are the symptoms of Pontiac Fever?

Answer 30

fever, headache, muscle aches, but no pneumonia. symptoms go away on their own

Question 31

Tell me about mycoplasmal pneumonia?!

Answer 31

gradual and insidious onset of several days to weeks. Presents w/ fever, malaise, persistent dry cough, headache, chills, scratchy sore throat, sore chest, tracheal tenderness, pleuritic chest pain

Question 32

How is chlamydiae transmitted?

Answer 32

attach to outer membrane of susceptible host cells and produce cytoplasmic inclusions which then release the matured inclusions to infect adjacent cells.

Question 33

How are the various chlamydia strains transmitted?

Answer 33

Pneumoniae - human to human Psittaci - birds to humans via respiratory route through direct contact or aerosolization Trachomatis - transmitted to infant when it passes through infected birth canal

Question 34

How do people get Legionnaire's disease?

Answer 34

when they breathe in mist or vapor that has been contaminated w/ the bacteria. it is NOT transmitted from person to person

Question 35

What age group is mycoplasmal pneumonia most common in?

Answer 35

the first 2 decades of your life, highest rate of individuals aged 5-20 years, rare in kids less than 5

Question 36

What time of the year does M. pneumoniae cause as many as 50% of the pneumonias?

Answer 36

summer

Question 37

What is the incubation period of mycoplasmal pneumonia?

Answer 37

3 weeks in contrast to that of influenza and other viral pneumonias which generally average a few days

Question 38

Where are epidemics of mycoplasmal pneumonia seen?

Answer 38

every 4-8 years in the general population and tend to be more frequent w/in close populations such as military and prison populations

Question 39

How is chlamydia Dxed?

Answer 39

IgM titer exceeding 1:16 or a 4-fold increase in IgG by MIF, PCR

Question 40

How is Legionnaire's Disease Dxed?

Answer 40

CXR for pneumonia, urinary antigen test, culture,

Question 41

How is mycoplasma Dxed?

Answer 41

lab test are of limited benefit b/c they tend to be nonspecific or within the normal range.

Question 42

When does one administer treatment for chlamydia?

Answer 42

when mixed infections with other organisms are present -- in 60% of cases, treat empirically

Question 43

What is the drug of choice for chlamydia?

Answer 43

doxy but not in kids less than 9 and pregos. Treat for 10-14 days

Question 44

What other drugs can be given for chlamydia?

Answer 44

erthyromycin, macrolides (arithromycin and clarithroymycin)

Question 45

What are the treatments for Legionella?

Answer 45

1. respiratory tract quinolones (floxacins) 2. macrolides ones used most frequently = levofloxacin and azithromycin

Question 46

When should mycoplasmal pneumonia be considered a possible etiology?

Answer 46

pt who presents with 3 weeks of more of a steadily progressive cough

Question 47

What drugs can be used for prophylaxis in households in which pts have underlying conditions predisposed to sever mycoplasmal infection. eg SCD or antibody deficiencies

Answer 47

macrolide o doxycycline