Chlamydia trachomatis, respiratory tract diseases caused by Chlamydia

Question 1

General Features and habitat of Chlamydiae Species (Chlamydia trachomatis)

Answer 1

Gram – (stains poorly with Gram staining) Pleomorphic shape (ovoid)
Reservoir- human genital tract and eyes

Question 2

Biochemical Properties of Chlamydiae Species

Answer 2

Obligate intracellular- cannot create his own ATP

Cell wall lacks muramic acid (no peptidoglycan)- but contains LPS

Bi-Phasic Life Cycle:
Elementary bodies (EB)- extracellular, infecting (inactive) form
Reticular bodies (RB)- intracellular, replicating (active) form

Elementary stage: bacteria outside of cells (infecting)

Reticular stage: The bacterium enters cell and replicate by binary fission into 2 bacteria,
then is released as elementary bodies and the cycle begins all over

Question 3

Pathogenesis of Chlamydiae Species

Answer 3

Transmitted by sexual contact (STD), at birth or by contaminated hands touching eyes

Question 4

Clinical Features of Chlamydiae Species

Answer 4

Trachoma (inclusion conjunctivitis)
Chlamydia (Sexually Transmitted Infection- STI) serotypes D-K
Lymphogranuloma Venereum (LGV)- serotypes L1-L3 (also STI but less common)
Complication- Sexually Acquired Reactive Arthritis (SARA)
Autoimmunity (cross-reactivity) causing a triad of symptoms (A.K.A Reiter’s syndrome)

Question 5

Trachoma (inclusion conjunctivitis)- serotypes A-C (A, B, Ba, C)

Answer 5

Blindness (leading cause of blindness in the world)

Due to chronic conjunctivitis that leads to conjunctival scarring and corneal scarring

Question 6

Chlamydia (Sexually Transmitted Infection- STI)- serotypes D-K

Answer 6

Watery discharge (in contrast with N. gonorrhea which has purulent discharge)

Lead to Pelvic Inflammatory Disease (PID), if left untreated- can cause infertility
In females: NGU, vaginitis or cervicitis; in males: urethritis, prostatitis

In newborns to infected mother- conjunctivitis and pneumonia (staccato cough)
Conjunctivitis occurs after ~1 week (compared to N. gonorrhea after 2-4 days)

Question 7

Lymphogranuloma Venereum (LGV)- serotypes L1-L3 (also STI but less common)

Answer 7

Present first with painless ulcers at the site of contact

Progress to swollen, tender lymph nodes (lymphadenopathy) at inguinal region

Tertiary (late) stage presents with ulcers, fistulas and genital elephantiasis

Question 8

Sexually Acquired Reactive Arthritis (SARA)

Answer 8

Autoimmunity (cross-reactivity) causing a triad of symptoms (A.K.A Reiter’s syndrome)

Reactive arthritis- usually in knees (joint inflammation)

Uveitis (eye inflammation)

Urethritis (urethra inflammation)

Question 9

Diagnosis of Chlamydiae Species

Answer 9

Giemsa staining or IF- inclusion bodies in cytoplasm of infected cells seen in microscope
ELISA- antigen detection from urine / other exudate or antibody detection
NAAT (Nucleic-Acid Amplification Test) = PCR

Question 10

Treatment of Chlamydiae Species

Answer 10

Macrolides (e.g. Azithromycin) or Doxycycline (Tetracycline)

Ceftriaxone- use if co-infected with N. gonorrhea, can treat both empirically

Question 11

Distinguishing Characteristics of Chlamydophila pneumoniae (TWAR* agent)

Answer 11

Potential association with atherosclerosis (plaque formation)

Question 12

Reservoir of Chlamydophila pneumoniae (TWAR* agent)

Answer 12

Human respiratory tract

Question 13

Transmission of Chlamydophila pneumoniae (TWAR* agent)

Answer 13

Respiratory droplets (common among school-aged children)

Question 14

Pathogenesis of Chlamydophila pneumoniae (TWAR* agent)

Answer 14

Intracellular growth- incubation period takes several weeks
Smooth muscle
Endothelial cells (of coronary arteries)
Macrophages

Obligate human pathogen

Question 15

Clinical Features of Chlamydophila pneumoniae (TWAR* agent)

Answer 15

Atypical (“walking”) pneumonia- affect single lobe

Minimal sputum
Prominent dry cough
Hoarseness
Can lead to bronchitis, sinusitis or pharyngitis

Question 16

Diagnosis of Chlamydophila pneumoniae (TWAR* agent)

Answer 16

Culture on living susceptible cell lines

Serology (most important)- from serum
Complement fixation (CF)
Indirect immunofluorescence (MIF) or ELISA

PCR- detects as few as 10-100 EBs from specimens include:
nasopharyngeal or throat swabs, broncho-alveolar lavage

Question 17

Treatment of Chlamydophila pneumoniae (TWAR* agent)

Answer 17

Macrolides (Erythromycin) or Doxycycline (Tetracycline)

Question 18

Prevention of Chlamydophila pneumoniae (TWAR* agent)

Answer 18

None

Question 19

Distinguishing Characteristics of Chlamydia psittaci

Answer 19

No glycogen in inclusion bodies

Question 20

Reservoir of Chlamydia psittaci

Answer 20

Zoonosis- birds, parrots, turkeys (domestic and wild)

Question 21

Transmission of Chlamydia psittaci

Answer 21

Dust from dried birds’ secretions and feces

Question 22

Pathogenesis of Chlamydia psittaci

Answer 22

Intracellular growth

Question 23

Clinical Features of Chlamydia psittaci

Answer 23

Psittacosis (A.K.A Ornithosis or Parrot Fever)

Atypical pneumonia with hepatitis

Cough may be absent

If present- unproductive first, then scant mucus

CNS and GI symptoms may be present

May also cause meningoencephalitis, myocarditis

Question 24

Diagnosis of Chlamydia psittaci

Answer 24

Culture on living susceptible cell lines

Serology (most important)- from serum
Complement fixation (CF)- 4x increase in antibody titer
Indirect immunofluorescence (MIF) or ELISA

PCR- detects as few as 10-100 EBs from specimens include:
nasopharyngeal or throat swabs, broncho-alveolar lavage

Question 25

Treatment of Chlamydia psittaci

Answer 25

Macrolides (Erythromycin) or Doxycycline (Tetracycline)

Question 26

Prevention of Chlamydia psittaci

Answer 26

Chemoprophylaxis of exotic birds with Tetracycline