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MHD 1 > L32 Chlamydia, Mycoplasma, Legionella > Flashcards

L32 Chlamydia, Mycoplasma, Legionella Flashcards

1
Q

What are the major shared features of Chlamydia, Mycoplasma, and Legionella?

A
  1. Do not Gram stain well
  2. Difficult to culture
  3. Frequently cause respiratory tract infection (upper respiratory tract, atypical community-acquired pneumonia)
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2
Q

Chlamydia, Mycoplasma, and Legionella do not stain well with Gram stain. Why?

A

Chlamydia and Legionella are intracellular bacteria. Mycoplasma has no cell wall.

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3
Q

Bacteria in the family Chlamydiaceae are ___ bacteria with a unique life cycle. Why do they need a host?

A

Obligate intracellular; they need the host cell for energy, as they do not produce ATP.

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4
Q

How are bacteria in the family Chalmydiaceae cultured?

A

Only within live cells, which is difficult

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5
Q

Describe the life cycle of Chlamydiaceae.

A
  1. Elementary bodies (small, infectious, non-replicative) attach to a specific host cell receptor.
  2. The elementary bodies are endocytosed into a phagosome.
  3. Within the cell, elementary bodies reorganize into large reticulate bodies (non-infections, replicative) within the phagosome.
  4. Reticulate bodies multiply via binary fission within the host cell. The phagosome enlarges into an inclusion.
  5. The reticulate bodies condense back into elementary bodies, which lyse the cell and are released. The cycle restarts
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6
Q

What is the difference between elementary bodies and reticulate bodies?

A
  1. Elementary body: infectious, non-replicative

2. Reticulate: non-infectious, replicative

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7
Q

Describe the structure of bacteria in the Chlamydiaceae family.

A
  1. Rigid cell membrane without peptidoglycan but high lipid content (confers rigidity)
  2. Inclusion bodies stain purple/blue with Giemsa
  3. Cell wall contains PBPs, but penicillin is not effective
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8
Q

What are the 3 clinically relevant species of Chlamydiaceae?

A
  1. C. trachomatis
  2. Chalmydophila psittaci
  3. Chlamydophila pneumoniae
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9
Q

Describe the structure of Mycoplasma.

A
  1. Smallest free living bacteria
  2. No cell wall; has single triple layered cell membrane (sterols)
  3. Requires cholesterol for growht
  4. Beta-lactams are ineffective
  5. Culture is difficult; use Eaton agar; fried egg appearance
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10
Q

Describe the pathogenesis of Mycoplasma in the respiratory tract.

A

Attach to cilia of the bronchial epithelium and stimulate a huge inflammatory response (cytokine storm)

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11
Q

Describe the pathogenesis of Mycoplasma in the UG tract.

A

Binds oligosaccharide receptors on mucosal epithelium using P1 adhesion; stimulates a huge inflammatory response (cytokine storm)

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12
Q

What are the 4 important types of Mycoplasma?

A
  1. Mycoplasma pneumoniae
  2. Mycoplasma hominis
  3. Mycoplasma genitalium
  4. Ureaplasma urealyticum
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13
Q

What are 3 Mycoplasma that can colonize the UG tract?

A

M. hominis, M. genitalium, U. urealyticum

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14
Q

Which Mycoplasma causes UG tract infection more commonly in women? In men?

A

Women: M. hominis
Men: M. genitalium

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15
Q

Describe the pathogenesis of Chlamydia trachomatis.

A

Major outer membrane proteins (MOMP) facilitate infection of non-ciliated epithelial cells on mucous membranes. This causes minute abrasions, followed by a robust inflammatory response (no long-term immunity).

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16
Q

Discuss the epidemiology of Chlamydia trachomatis.

A
  1. Most common STI in the U.S>
  2. > 1.3 million infections/year; rates are increasing
  3. Ocular trachoma endemic in Arica/Asia/South America
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17
Q

How is Chlamydia trachomatis transmitted?

A

Direct contact across mucosal surfaces (anogenital, oropharyngeal)

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18
Q

What are the major clinical manifestations of infection with Chlamydia trachomatis?

A
  1. UG tract infections
  2. Eye disease: ocular trachoma and adult inclusion conjunctivitis
  3. Lymphogranuloma venereum
  4. Congenital infection: infant inclusion conjunctivitis (most common cause of neonatal conjunctivitis) and pneumonitis
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19
Q

Which of the clinical manifestations of infection with Chlamydia trachomatis are most common?

A

UG tract infections

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20
Q

UG tract infections with Chlamydia trachomatis are seen in which populations? Discuss the transmission rate.

A

Sexually active young adults and teens; 25% of men are asymptomatic. 80% of women are asymptomatic. High transmission rate

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21
Q

What types of UG infections are caused by Chlamydia trachomatis in men?

A

Urethritis, epididymitis, prostatitis, proctocolitis

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22
Q

What types of UG infections are caused by Chlamydia trachomatis in women?

A

Cervicitis, PID, proctocolitis

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23
Q

What is ocular trachoma and in what populations is it common?

A

Chronic inflammatory granulomatous eye disease; follicular conjunctivitis causes eyelids to curl, scars the cornea, ends in blindness; common in poor rural areas and in children

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24
Q

How are congenital infections of Chlamydia trachomatis transmitted? Discuss the manifestations and their symptoms.

A

Via infected birth canal

  1. Infant inclusion conjunctivitis (eyelid swelling, mucopurulent discharge)
  2. Pneumonitis (rhinitis, staccato cough)
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25
Q

Describe LGV. Discuss the incubation period and its prevalence in the world.

A

Suppurative multiocular inguinal lymph nodes (buboes) enlarge and form a draining fistula. Fever, chills, myalgia, headache, proctococlitis, primary lesions - painless papule or ulcer

Incubation: 1-4 weeks
Sporadic in US, prevalent elsewhere

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26
Q

How is Chlamydia trachomatis diagnosed?

A
  1. Culture of epithelial tissue
  2. Ag detection - MOMP (direct immunofluorescence stain, ELISA)
  3. NAAT (preferred)
  4. Serology
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27
Q

How is UG tract/ocular infection of Chlamydia trachomatis treated?

A

Azithromycin

Alternative: doxycycline

Also: ocular surgery

28
Q

How is congenital infection of Chlamydia trachomatis treated?

A

Erythromycin

29
Q

How is LGV treated?

A

Doxycycline

Also: drain lesions

30
Q

Chlaymydophila pneumoniae is common in which populations?

A

School age children (can be seen in all ages)

31
Q

How is C. pneumoniae transmitted?

A

Respiratory droplets

32
Q

Describe the clinical manifestations of C. pneumoniae.

A
  1. Atypical community-acquired pneumonia
  2. Bronchitis
  3. Sinusitis
  4. Pharyngitis
33
Q

How is C. pneumoniae diagnosed?

A

Difficult - serology or NAATs (preferred)

34
Q

How is C. pneumoniae treated?

A

Azithromycin, doxycycline, respiratory fluoroquinolone

35
Q

What is the primary reservoir of Chlamydophila psittaci?

A

Psittacine birds (parrots, parakeets)

36
Q

How is C. psittaci transmitted?

A

Respiratory secretions or droppings of infected birds

37
Q

What is the primary clinical manifestation of C. psittaci?

A

Lower respiratory tract infection (headache, fever, chills, aches, dry cough, bilateral pneumonia)

38
Q

How is C. psittaci diagnosed?

A

Difficult to do - serology

39
Q

How is C. psittaci treated?

A

Doxycycline

Alternative: azithromycin

40
Q

Discuss the epidemiology of Mycoplasma pneumoniae.

A
  1. Epidemics occur every 4-7 years
  2. Cause of 5-15% of community acquired pneumonia
  3. Prevalent in school age/teens, military, prisons
41
Q

How is M. pneumoniae transmitted?

A

Respiratory droplets

42
Q

What is the incubation period for M. pneumoniae?

43
Q

What are the clinical manifestations of infections with M. pneumoniae?

A

Headache, fever, malaise, chills, rhinorrea, myalgia, chest pain, sore throat, hoarseness, severe non-productive cough that later becomes productive with white or clear sputum

44
Q

What are the rare secondary complications of M. pneumoniae?

A
  1. Meningoencephalitis
  2. Transverse myelitis and paralysis
  3. Pericarditis
  4. Cold agglutinin (IgM) hemolytic anemia
  5. Arthritis
  6. Mucocutaneous lesions and rashes
45
Q

How is M. pneumoniae diagnosed?

A
  1. Eaton agar culture (10-14 days)
  2. Serology
  3. NAAT
46
Q

How is M. pneumoniae treated?

A

Azithromycin, doxycycline, respiratory fluroquinolones

47
Q

What are the clinical manifestations of Mycoplasma hominis?

A
  1. Vaginosis
  2. Pyelonephritis
  3. Endometritis (PID)
  4. Postpartum fever
  5. Chorioamnionitis
  6. Systemic infection in immunocompromised patients
48
Q

How is M. hominis diagnosed?

A
  1. Culture (difficult)

2. NAAT

49
Q

How is M. hominis treated?

A

Doxycycline

50
Q

What are the clinical manifestations of M. genitalium?

A
  1. Urethritis (men)
  2. Cervicitis/PID
  3. Tubal infertility (?)
  4. Spontaneous abortions (?)
51
Q

How is M. genitalium diagnosed?

A
  1. > 5 WBC/hpf on urehtral/cervical swab + negative gonorrhea/chlamydia tests
52
Q

How is M. genitalium treated?

A

Azithromycin (increasing resistance), doxycyclin, moxifloxacin

53
Q

What are the clinical manifestations of Ureaplasma urealyticum?

A
  1. Urethritis (men and women)
  2. Pyelonephritis
  3. Spontaneous abortion/premature birth
  4. Bacteremia in immunocompromised patients
  5. Hyperammonemia (ureaplasma splits urea)
54
Q

How is U. urealyticum diagnosed?

A
  1. Culture (difficult)

2. NAAT

55
Q

How is U. urealyticum treated?

A

Azithromycin, doxycycline

56
Q

Describe the structure of Legionella.

A
  1. Slender, pleomorphic, GN bacilli (poor Gram staining)
  2. Dieterle’s silver stain of tissue
  3. Obligate aerobe
  4. Non-fermenting (get energy from amino acids, not carbs)
  5. Fastidious growth requiring buffered charcoal yeast extract agar + cysteine iron salts
57
Q

Describe the pathogenesis of Legionella.

A

OMP porin binds to C3B receptor on phagocytes. The bacteria is endocytosed. It inhibits phagolysosome fusion and multiplies intracellularly. It lyses the vacuole and kills the cell.

58
Q

Discuss the epidemiology of Legionella.

A
  1. Ubiquitous aquatic organism (lakes, streams, water reservoirs, etc.)
  2. 90% of infections are caused by L. pneumophila
  3. 1200-2000 cases reported each year
59
Q

How is Legionella transmitted?

A

Inhalation of infectious aerosoles; both community acquired and nosocomial

60
Q

What are risk factors for acquiring Legionella?

A
  1. Transplant recipient
  2. Smoking
  3. Chronic lung disease
  4. Being an older man
61
Q

What are the two major clinical manifestations of Legionella?

A
  1. Pontiac feber

2. Legionellosis

62
Q

Describe Pontiac fever; discuss the treatment and incubation period.

A

Febrile, influenza-like illness with NO pneumonia; 1-2 day incubation; self-limiting

63
Q

Describe Legionellosis, including the incubation period and mortality rate.

A

Fever, chills, cough, headache, sever pneumonia, multisystem infection, hyponatremia; 2-10 day incubation; 15-20% mortality

64
Q

How is Legionellosis diagnosed?

A
  1. Silver stain
  2. Culture on charcoal with iron and cysteine
  3. Urinary antigen test (ELISA)
  4. Serology
  5. NAAT
65
Q

What is the treatment for Legionellosis?

A

Azithromycin or respiratory fluoroquinolones

MHD 1 (58 decks)

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