L21 Chlamydia, Mycoplasma and Q Fever Flashcards
Clinical Significance of Chlamydia?
STIs
Ocular Infections
Respiratory Tract Infections
Life Cycle of Chlamydia
Exists in 2 form:
Elementary Bodies (EB) - Infectious Form
Infectious
Spore like
Extracellular: Exists outside of cell
Rigid cell wall w/ crosslinked disulfide bonds
Protects bacteria
Reticulate Body (RB) - Reproductive Form
Non-Infectious
Metabolically active
Replicates in this form
Fragile cell membrane
Life Cycle of Chlamydia
Elementary Bodies (EB) - Infectious Form
Spore like
Extracellular: Exists outside of cell
Rigid cell wall w/ crosslinked disulfide bonds - Protects bacteria
Reticulate Body (RB) - Reproductive Form
Non-Infectious: Replicates in this form
Metabolically active
Fragile cell membrane
Chlamydia Trachomatis Serovars
Site of infections?
Conditions?
Diagnosis?
Treatment
STI?
Chlamydia Trachomatis Ocular Diseases?
Chronic Disease: Serotype A-C => Chronic Follicular Keratoconjunctivitis
Acute Disease : Serotype D-K => Inclusion Conjunctivitis
C. Trachomatis (A-C) = ______________
Condition Associated?
Manifestation?
Spread?
C. Trachomatis (A-C) = Trachoma
Chronic Follicular Keratoconjunctivitis
Infection of conjunctival epithelial cells → follicle development
=> Multiple re-infections disrupt the frictionless movement of the eyelid over the cornea
=> Conjunctival scarring and corneal damage
=> blindness
MOST COMMON cause of preventable blindness
Primarily in developing countries: Asia, Middle East, Asia
Person to person spread via: Contact, Droplets, Flies
Trachomatous TRICHIASIS: eyelashes rub against the cornea
MOST COMMON cause of preventable blindness?
Chronic Follicular Keratoconjunctivitis
Caused by Chlamydia A-C
C. Trachomatis (D-K): __________________________
Conditions Associated?
Sites Infected?
Treatment?
C. Trachomatis (D-K): Inclusion Conjunctivitis and STIs
Chlamydia Inclusion Conjunctivitis
STI of adults
- Most have concurrent genital tract infection
- Acute infection (not chronic like Trachoma)
- Not purulent
No corneal scarring or blindness!!
Neonatal Inclusion Conjunctivitis
Transmitted from genital infection at delivery- Mother has chlamydia (can also occur from Caesarean section)
Occurs 5 days to 6 weeks after delivery
Acute watery then mucopurulent discharge
Can lead to infant pneumonia syndrome
Treatment oral erythromycin
Sexually Transmitted Genital Tract Infections
Cervicitis: females
Urethritis: Males
Epididymitis
Pharyngeal Infection
Pelvic Inflamatory Disease
C. Trachomatis (L1-L3): _____________________
Sites of infection
Epidemiology?
C. Trachomatis (L1-L3): Lymphogranuloma Venereum (LGV)
More aggressive and invasive infection
L= Lymphotropic: Infection of lymphatics, lymph nodes and anorectal tissues = proctitis
Genital and colorectal tissues affected
Epidemiology:
Tropical and subtropical areas
Outbreaks in men who have sex with men
Highly associated w/ HIV infection
70% of MSM with LGV have HIV in Ireland
Diagnosis of Chlamydia Trachomatis?
Depends on Serotype/Site of infection
Trachoma: Clinical, clearly distinct signs esp. in endemic region
NAAT (nucleic acid amplification test)
D-K: Urethritis/cervicitis: genital tract specimen or urine
L1-L3: LGV
Treatment of Chlamydia Trachomatis
NOT CULTURABLE due to intracellular nature (Want therapy with good intracellular penetration)
Trachoma (A-C): Erythromycin or Doxycycline
D-K:
Urethritis / cervicitis: Doxycycline
Neonatal conjunctivitis: Erythromycin
LGV (L1-3) : Doxycycline
Chlamydophila Psittaci
Transmission?
Manifestation?
Diagnosis?
Treatment?
Chlamydophila Psittaci
Zoonotic infection: Psittacosis (parrot fever)
Transmission via Inhalation of respiratory secretions or droppings from infected birds
Acute pneumonia, often bilateral and severe
Serology for diagnosis
Treatment
– Doxycycline
– Don’t forget to treat the bird!
What is repsonsible for Psittacosis (parrot fever)
Chlamydophila Psittaci
Chlamydophila Pneumoniae
Transmission?
Clinical features?
Diagnosis?
Treatment?
Chlamydophila Pneumoniae
Transmission
– Droplet spread person-to-person
– Children and adolescents
Clinical features
– Upper respiratory tract infection – flu like
– Pneumonia with atypical features, often hoarse voice.
– Often have co-infection
– No seasonal variation
Diagnosis
– Serology
– PCR respiratory tract specimen
Treatment
Doxycycline
Macrolides
Mycoplasma Pneumoniae:
Significance?
Anaerobe/Aerobe?
Microbe Characteristics?
Culture Characteristics?
Mycoplasma Pneumoniae
Smallest free-living micro-organism
Generally facultative anaerobes (Except M.pneumoniae - aerobe)
Intracellular infection
No rigid cell wall
– Cells bound by sterol containing membrane
– Stain poorly in lab
Require specialized media for laboratory culture– Not routinely performed
“Fried egg” colonies on specialized agar plates after several days of incubation
Smallest free-living micro-organism?
Mycoplasma Pneumoniae
Microbe with Fried Egg Colonies?
Mycoplasma Pneumoniae
Epidemiology/Transmission of Mycoplasma Pneumoniae
Epidemiology
– One of commonest causes of respiratory tract infections
– Occurs in close communities – families, military etc.
– Overall mortality rate very low
Transmission
–Person-to-person by respiratory droplet spread
- Nasopharyngeal secretions – coughing, sneezing
- Prolonged shedding occurs after clinical illness
– Low infectious dose (small amount for infection)
Clinical Features of Mycoplasma Pneumoniae
Clinical features
Upper respiratory tract infection
• Pharyngitis
Pneumonia
- Insidious onset of dry cough, fevers, malaise, headache
- Often called “walking pneumonia” – mild illness
Extrapulmonary disease (due to dysregulation of immune system)
- Skin: rashes
- Neurological: encephalitis; Guillain-Barré syndrome: ascending flaccid paralysis: starting in fingers and toes, can progress to diaphragm or the heart
- Joints: arthralgia
- Cardiac: myocarditis; pericarditis
- Hemolytic anemia - cold agglutinins
Guillain-Barré syndrome is associated with what Pathogen?
Mycoplasma Pneumoniae
walking pneumonia is caused by what pathogen?
Mycoplasma Pneumoniae
Diagnosis of Mycoplasma Pneumoniae?
No cell wall => does not take up Gram stain
Fastidious growth requirements => difficult to culture from sputum
Serology: Presence of M. pneumoniae IgM (more reliable in children and teenagers)
Molecular analysis: Direct PCR for M. pneumoniae DNA on respiratory sample
Cold Agglutinins
Supportive only, not diagnostic
IgM antibodies form against I antigen on erythrocyte membranes
Agglutination of RBCs at low temperatures => hemolysis
Hemolysis is not usuall_y clinically significant except in Sickle Cell_
Treatment of Mycoplasma Pneumoniae?
Mild illness often self-limiting so antibiotics often not required
Mycoplasma do not have a cell wall!!!! => cell-wall active agents (β-lactams: penicillins, cephalosporins) NOT suitable
Ribosomal Targeting Antimicrobials Effective
– Macrolides eg. Clarithromycin
– Tetracyclines eg. Doxycycline
– Fluoroquinolones eg. Levofloxacin
Coxiella Burnetii aka. (______)
Microbiology?
Transmission?
Incubation?
Groups at risk
Coxiella Burnetii aka. (Q FEVER)
Microbiology
Gram negative bacillus
Intracellular, grows in the phagosome
Alveolar macrophage
Spore-like form: survives in environment outside host for prolonged periods. Resistant to heat and drying
High infectivity: potential biological weapon
Transmission
– Inhalation of aerosols from contaminated soil or animal waste
– Ingestion of unpasteurised dairy products (rare)
Risk groups – Farmers, veterinarians slaughterhouse/abattoir workers
Incubation period– 2-5 weeks
Clinical feautres of
Clinical features of Q Fever (Coxiella Burnetii)
Often asymptomatic
Acute Q fever
Self-limiting febrile illness
Pyrexia of unknown origin
Hepatitis
Miscarriage/ preterm delivery in pregnancy
Chronic Q fever
Rare
Culture negative endocarditis most common manifestation
Risk factors
– Immunocompromised
– Patients infected during pregnancy (risk of pregnancy loss)
– Prosthetic heart valves
Treatment of Coxiella Burnetii (Q Fever)
Treatment
- Doxycycline + Hydroxychloroquine
- Co-trimoxazole in pregnancy
- Year-long or lifelong therapy for endocarditis
What do Chlamydia Mycoplasma and Q Fever have in common?
Micro: Obligate Intracellular INnections, Can’t gram stain
Antibiotics: Penicillins are ineffective, antibiotics must work intracellularly (Doxycycline, Macrolides, Fluoroquinolones)
Presentation: Often Flu-Like
Diagnosis: Nucleic Acid Amplification Tests (NAAT)/PCR
