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MHD #3 > Chlamydia > Flashcards

Chlamydia Flashcards

1
Q

Chlamydia cell membrane

A
  • cell membrane without peptidoglycan (penicillins have no activity) `
  • Rigid, high lipid content
  • Stain purple Giemsa (elementary), blue (reticulate)
  • Gram reaction – negative or variable – not used
  • Cell wall contains PBPs, but penicillins not clinically effective
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2
Q

Chlamydia are intracellular or extracellular and depend on the host for

A 
obligate intracellular (contain DNA and RNA)
depend on the host for energy (produce no ATP) derive en`ergy in endosome
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3
Q

what is the infectious form of chlamydia

A

elementary body

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4
Q

Chlamydia causes disease by

A

Gain access through minor abrasions
Produce significant cell damage
Induce Severe inflammatory response


immunity is not long lived

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5
Q

Trachoma

A

• chronic follicular conjunctivitis, eyelid curling and scarring
• seen in underdeveloped countries
(Africa, Asia, Mediterranean basin)
• major cause of blindness worldwide due to increased vascularization/ scarring

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6
Q

Trachoma is caused by which immunotypes

A

immunotypes A, B, Ba, and C

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7
Q

what is the treatment and prevention for trachoma?

A

surgery, tetracyclines 1% ointment, azithromycin (must get intracellular)

Prevention – improved hygienic standards

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8
Q

C. trachomatis Genital Tract infections are caused by which immunotypes

A

Serotypes D-K

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9
Q

C. trachomatis serotypes D-K infections clinical presentations

A

Sexually active, mostly teenagers

  • high rate of transmission
  • 2-6 week incubation
 (easily transmitted during this time)
  • urethritis (males), may be relatively assymp
  • Epidymitis, prostatitis (
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10
Q

Inclusion conjunctivitis

A
  • Most common cause of neonatal conjunctivitis in U.S. – can occur in adults as well.
  • Contact with vaginal secretions
  • Serotypes D – K (different from trachoma)
  • 2-25% after birth- mucopurulent eye discharge
  • Diagnosis = inclusions demonstrated or by culture
  • Treatment = tetracycline
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11
Q

Neonatal Pneumonia from C. trachomatis

A

Common cause of newborn pneumonia
2-12 weeks after birth

Tachypnea, paroxysmal cough
Seen with inclusion conjunctivitis

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12
Q

Lymphogranuloma venereum is caused by what serotypes of C. trachomatis

A

L1, L2, L3

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13
Q

Lymphogranuloma venereum is

A

suppurative multilocular inguinal lymph nodes (bubos) (swelling of inguinal lymph nodes)
fistula drainage
strictures (urethra, rectal)
perirectal abscess

not common in US

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14
Q

Chlamydia trachomatis can be diagnosed by

A

epithelial scrapings

  • isolation of organism
  • cell culture

non-culture
- Direct flouorescent antibody (DFA)
monoclonal antibodies against elementary bodies
Species specific Major outer membrane protein
Sensitivity 80-90%, specificity 99%
- lipopolysaccharide enzyme assays
- DNA probe of ribosomal RNA
Sensitivity 85%, 99% specificity


Serology helpful in LGV (1:64)

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15
Q

Chlamydia trachomatis Treatment

A

Tetracyclines
tetracycline 2g/d X 7 days
doxycycline 200/d X 7 days


Quinolones
ofloxacin/levaquin X 7days


Azithromycin * preferred in ED
1g / 1 dose > 95% cure


Erythromycin
2 g/d X 7 days (pregnant)

standard treatment is 7 days (not susceptible to pcn)

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16
Q

Chlamydia trachomatis Lymphogranuloma
 treatment

A

tetracycline / erythromycin
3 week course
may not influence ulcerations
drainage may be necessary

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17
Q

Chlamydia pneumoniae clinical presentations

A

pharyngitis
laryngitis
pneumonia (walking)/ community aquired

18
Q

C. pneumonia serotype

A

TWAR

19
Q

how is C. Pneumonia spread

A

respiratory

20
Q

how is C. pneumonia diagnosised

A

its usually not bc they treat all pneumonias with an emperic therapy that would cover C. pneumonia but can be done via serology

21
Q

how is C. pneumonia treated

A

tetracycline, erythromycin, fluoroquinolones 10-14 days

22
Q

C. psittaci comes from

A

inhalation of respiratory secretions or droppings of infected birds- enters lung, spread to other organs via RE system
Psittacine birds (parrots, parakeets)
Ornithosis (pigeons, chickens, ducks, geese, turkeys)


23
Q

C. psittaci symptoms

A

Lower respiratory tract infection

headache, fever, muscle aches, dry cough, bilateral pneumonia


24
Q

diagnosis and treatment of C. psittaci

A

Diagnosis = complement fixation
Four fold increase or IgM >1:16


Treatment = tetracycline, erythromycin

25
Q

M. pneumoniae characteristics

A
  • 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-Smallest organism growing in cell free medium - Stained with fluorescent Aby

26
Q

M. pneumonia causes disease by

A

acting like a super antigen - most of the disease is due to the immune response

TNF, IL-1, IL-6

27
Q

who most commonly gets Mycoplasma pneumoniae

A

epidemics every 4 -7 years
5 - 15% of community acquired pneumonia

peak incidence in teenagers

spread among families

  • school age children
  • respiratory droplets
  • incubation 3 weeks

28
Q

Mycoplasma pneumoniae clinical symptoms

A

headache, fever, malaise, chills (not rigors)


rhinorrhea, myalgias, chest pain, sore throat, hoarseness 25 -50%


CXR findings out of proportion to clinical presentation and findings


non-productive cough, later, white/ clear sputum



29
Q

diagnosis of M. pneumoniae

A

• CXR
may appear severe, interstitial pattern
not diagnostic

  • culture (10-14 days)
  • serology (high titer > 1:32)
  • PCR
  • cold hemagglutinins- bind I Ag or erythrocytes @ 40C >1:128
30
Q

treatment of M. pneumoniae

A

• macrolides:
erythromycin
azithromycin
clarithromycin


  • tetracyclines

  • fluoroquinolones

an empiric therapy for pneumonia will include one

31
Q

Legionella: Morphology and Staining

A

Slender Gram-negative rods (0.3-0.9 x 2 µm)

Do not stain with Gram stain in clinical specimens
 (difficult to stain)
Seen in tissue with Dieterle’s silver stain

32
Q

Legionella common serotypes

A

serotype 1 is the most common and community acquired. (6 is also fairly common)

The other serotypes are hospital associated

33
Q

Legionella: Cultural Characteristics

A 
Obligate aerobe
Non-fermentative
Derive energy from amino acids
Fastidious growth requirements
Motile
Catalase positive
Weakly oxidase positive
Beta-lactamase positive
34
Q

Legionella: Epidemiology

A

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

Found in potable water (hot water) systems
Survives in biofilms

Occurs as sporadic disease or as epidemics
1200-2000 cases/year reported (estimated 10,000-12,000)

35
Q

Host risk factors for legionella

A

Recipient of a transplanted organ
Cigarette smoking
Chronic lung disease

not common in a healthy host (some healthcare worker associated)

36
Q

how does the immune system fight legionella

A

Cell mediated

Requires sensitized T-cells to activate macrophages

37
Q

Legionella: Clinical Manifestations

A

Pontiac Fever
Legionellosis
Asymptomatic infection common

38
Q

Pontiac Fever

A

febrile influenza-like illness without respiratory component
Short incubation – 1-2 days
Self-limited
due to Legionella infection

39
Q

Legionellosis

A 
(severe pneumonia)
Longer incubation – 2-10 days
Multilobar pneumonia
Multisystem disease: GI, liver, kidney, CNS
15-20% mortality
40
Q

Legionella: Laboratory Diagnosis

A 
Microscopy -- not easy
Gram stain not helpful
Tissue Dieterle Silver stain 
Direct Fluorescence antibody test
Low sensitivity

Culture
Expectorated sputum – low yield
BAL, lung biopsy, pleural fluid, other body fluid or tissue
Special Media: Buffered charcoal yeast extract agar (BYCE)

** Urinary antigen test (most common)
ELISA detects L. pneumophila serogroup 1
60-90% sensitive
Sensitivity increases with severity of disease

PCR

Serology – requires 4-fold titer rise to 1:128 or greater

41
Q

Legionella: Treatment

A

Antibiotics with intracellular activity required

Macrolides: erythromycin, clarithromycin, azithromycin


Fluoroquinolones: ciprofloxacin, moxifloxacin

42
Q

Legionella: Prevention

A 
Eliminate or reduce numbers in water supply
Clean reservoirs (like Air-conditioning cooling towers)

Remove from potable water systems by:
Superheating
Hyperchlorination or other chlorine-
employing method
Copper/silver ionization

MHD #3 (11 decks)

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