Chlamydia/Mycoplasma/Legionella

Question 1

Chlamydia trachomatis diseases

Answer 1

Eye Trachoma/Neonatal Conjunctivitis/Genital Tract Infection

Question 2

Chlamydia pneumoniae diseases

Answer 2

Respiratory Illness - atypical pneumonia

Question 3

Chlamydia psittaci diseases

Answer 3

Zoonosis from birds that presents as a mild influenzal disease, but can develop into a rapidly severe and fatal pneumonia

Question 4

Mycoplasma pneumoniae diseases

Answer 4

Tracheobronchitis manifested by headache, fever, and malaise, followed 2 – 4 days later by cough

Question 5

Legionella diseases

Answer 5

SHORT INCUBATION
Pontiac Fever–febrileinfluenza-likeillness without respiratory component

LONG INCUBATION
Legionellosis (severe pneumonia)

Question 6

What are the various forms of chlamydia in its life cycle?

Answer 6

Elementary Body - infectious form that is uptaken into the cell via a phagosome

Reticulate Body - this is the reorganized EB after it enters the cell and it divides by binary fission until the entire cell is filled with the organisms

Question 7

What is the major virulence factor of Chlamydia?

Answer 7

Heat Shock Proteins that provokes a potent inflammatory response causing tissue damage, and is the major virulence factor identified.

Question 8

What is the major virulence factor of Mycoplasma?

Answer 8

P1 Protein.

M. Pneumonia attaches to cilia and microvilli lining of bronchial epithelium mediated by cytoadhesion protein called P1. The binding results in a coupling with oligosaccharide receptors, and interferes with ciliary action. An inflammatory response follows similar to that of a superantigen, resulting in desquamation, with resulting infiltration of lymphocytes and plasma cells resulting in thickened walls of bronchial tree.

Question 9

Are Chlamydia intracellular or extracellular bacteria?

Answer 9

Obligate Intracellular bacteria

Question 10

What is the the energy source of Chlamydia?

Answer 10

They are host cell dependent for energy as they produce no ATP

Question 11

What are the manifestations of eye trachoma?

Answer 11

Chronic follicular conjunctivitis, eyelid curling and scarring

Question 12

What immunotypes of C. trachomatis causes trachoma?

Answer 12

A through C

Question 13

What immunotypes of C. trachomatis causes genital tract infection?

Answer 13

D through K

Question 14

What are the manifestations of C. trachomatis genital tract infection?

Answer 14

Males
• Urethritis (males), may be relatively assymp
• Epidymitis, prostatitis (less than 35 yr)

Females
• cervicitis , usually assymptomatic
– salpingitis, PID ; high association with infertility

Question 15

How does C. trachromatis cause infant conjunctivitis?

Answer 15

Contact with vaginal secretions during birth

Most common cause of neonatal conjunctivitis in U.S.

Question 16

What immunotypes of C. trachomatis cause infant conjunctivitis?

Answer 16

D through K

The same as that cause genital tract infection

Question 17

What other infection in neonates is C. trachomatis associated with?

Answer 17

Infant Pneumonia

Question 18

What immunotype of C. trachomatis is associated with lymphogranuloma venereum?

Answer 18

L1, L2 and L3

Question 19

What is a common cause of community pneumonia?

Answer 19

C. pneumonia

Question 20

What is the reservoir of C. psittaci?

Answer 20

Birds like parrots and parakeets

Question 21

What is the main infection of C. psittaci?

Answer 21

Lower respiratory tract infection

Question 22

What is the appearance of M. pneumoniae on cell culture like?

Answer 22

Fried egg

Question 23

What is the pathogenesis of M. pneumoniae?

Answer 23

– smallest organisms that replicate on complex cell free medium
– no cell wall, single triple layered membrane (sterols), requires cholesterol for growth
– divides by binary fission
– fried egg appearance on culture after days
– binds oligosaccharide receptors- adhesion P1

Question 24

What are some other diseases that Mycoplasma may cause?

Answer 24

• Guillain-Barre
• Cardiac
• Skin

Question 25

What is characteristic about the CXR of Mycoplasma infections?

Answer 25

They will be out of proportion with the severity of the infection

Question 26

What Gram is Legionella?

Answer 26

Gram negative. But they do not stain clinically

Question 27

What is the aerobic status of Legionella?

Answer 27

• Obligate aerobe

Question 28

Are Legionella catalase positive or negative?

Answer 28

Catalase positive

Question 29

What is the reservoir of Legionella?

Answer 29

• Lives in water
– Aquatic lakes
– Amplified in man made reservoirs
• Enhanced by warm temperature, stagnation, scale, sediment and commensal algae, protozoa and bacteria

Question 30

What is the pathogenesis of Legionella?

Answer 30

• OMP (porin) binds C3b complement receptor on mononuclear phagocytes
• Endocytosis 􏰁inhibit phagolysosome fusion leading to 􏰁intracellular multiplication
• Kill cell with lysis of vacuole

Question 31

What are the main clinical manifestations of Legionella infection?

Answer 31

Short Incubation • Pontiac Fever–febrile influenza-like illness without respiratory component

Long Incubation • Legionellosis (severe pneumonia)

Question 32

How can Legionella infection be prevented?

Answer 32

• Cooling of water towers

- Superheating of water