Chlamydia Flashcards
Chlamydia cell membrane
- 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
Chlamydia are intracellular or extracellular and depend on the host for
obligate intracellular (contain DNA and RNA) depend on the host for energy (produce no ATP) derive en`ergy in endosome
what is the infectious form of chlamydia
elementary body
Chlamydia causes disease by
Gain access through minor abrasions
Produce significant cell damage
Induce Severe inflammatory response
immunity is not long lived
Trachoma
• 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
Trachoma is caused by which immunotypes
immunotypes A, B, Ba, and C
what is the treatment and prevention for trachoma?
surgery, tetracyclines 1% ointment, azithromycin (must get intracellular)
Prevention – improved hygienic standards
C. trachomatis Genital Tract infections are caused by which immunotypes
Serotypes D-K
C. trachomatis serotypes D-K infections clinical presentations
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 (
Inclusion conjunctivitis
- 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
Neonatal Pneumonia from C. trachomatis
Common cause of newborn pneumonia
2-12 weeks after birth
Tachypnea, paroxysmal cough
Seen with inclusion conjunctivitis
Lymphogranuloma venereum is caused by what serotypes of C. trachomatis
L1, L2, L3
Lymphogranuloma venereum is
suppurative multilocular inguinal lymph nodes (bubos) (swelling of inguinal lymph nodes)
fistula drainage
strictures (urethra, rectal)
perirectal abscess
not common in US
Chlamydia trachomatis can be diagnosed by
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)
Chlamydia trachomatis Treatment
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)
Chlamydia trachomatis Lymphogranuloma treatment
tetracycline / erythromycin
3 week course
may not influence ulcerations
drainage may be necessary
Chlamydia pneumoniae clinical presentations
pharyngitis
laryngitis
pneumonia (walking)/ community aquired
C. pneumonia serotype
TWAR
how is C. Pneumonia spread
respiratory
how is C. pneumonia diagnosised
its usually not bc they treat all pneumonias with an emperic therapy that would cover C. pneumonia but can be done via serology
how is C. pneumonia treated
tetracycline, erythromycin, fluoroquinolones 10-14 days
C. psittaci comes from
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)
C. psittaci symptoms
Lower respiratory tract infection
headache, fever, muscle aches, dry cough, bilateral pneumonia
diagnosis and treatment of C. psittaci
Diagnosis = complement fixation
Four fold increase or IgM >1:16
Treatment = tetracycline, erythromycin
M. pneumoniae characteristics
- 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
M. pneumonia causes disease by
acting like a super antigen - most of the disease is due to the immune response
TNF, IL-1, IL-6
who most commonly gets Mycoplasma pneumoniae
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
Mycoplasma pneumoniae clinical symptoms
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
diagnosis of M. pneumoniae
• 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
treatment of M. pneumoniae
• macrolides:
erythromycin
azithromycin
clarithromycin
- tetracyclines
- fluoroquinolones
an empiric therapy for pneumonia will include one
Legionella: Morphology and Staining
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
Legionella common serotypes
serotype 1 is the most common and community acquired. (6 is also fairly common)
The other serotypes are hospital associated
Legionella: Cultural Characteristics
Obligate aerobe Non-fermentative Derive energy from amino acids Fastidious growth requirements Motile Catalase positive Weakly oxidase positive Beta-lactamase positive
Legionella: Epidemiology
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)
Host risk factors for legionella
Recipient of a transplanted organ
Cigarette smoking
Chronic lung disease
not common in a healthy host (some healthcare worker associated)
how does the immune system fight legionella
Cell mediated
Requires sensitized T-cells to activate macrophages
Legionella: Clinical Manifestations
Pontiac Fever
Legionellosis
Asymptomatic infection common
Pontiac Fever
febrile influenza-like illness without respiratory component
Short incubation – 1-2 days
Self-limited
due to Legionella infection
Legionellosis
(severe pneumonia) Longer incubation – 2-10 days Multilobar pneumonia Multisystem disease: GI, liver, kidney, CNS 15-20% mortality
Legionella: Laboratory Diagnosis
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
Legionella: Treatment
Antibiotics with intracellular activity required
Macrolides: erythromycin, clarithromycin, azithromycin
Fluoroquinolones: ciprofloxacin, moxifloxacin
Legionella: Prevention
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
