Transcript Objectives

Objectives
• By the end of this lecture the student must be:
A) Identify the genus Rickettsiae, Chlamydiae, and
Mycoplasma
B) B) describe the chemical tests for this genus
• C) Differentiate between different sps.
• D) List and match the symptoms, diagnosis
and treatment for different sps.
Rickettsiae and Chlamydiae
• Similarity between Rickettsiae & Chlamydiae
• Rickettsiae are similar to Chlamydia in that
 Both are obligate intracellular energy parasites
 Both are similar in size as large viruses
 Both grow in living media (yolk sac of chick embryo)
Share
with
viruses
 They have both DNA and RNA
 They have ribosomes
 Both are replicate by binary fission
 Both are sensitive to antibacterial agents
Share with
bacteria
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Rickettsiae and Chlamydiae
• Rickettsiae are different to Chlamydia in that
 Require arthropod vector (except for Q fever)
 Replicates
freely in cytoplasm while Chlamydia
replicates in endosomes
 Ricketsia has tropism for endothelial cell
that line blood
vessels while Chlamydia like columnar epithelium
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RICKETTSlACEAE
• Small Gram-negative coccobacilli (0.3-0.5 ~m in length)
that stain poorly spore forming
• Cell membrane is similar to that of Gram-negative bacteria;
contains LPS and peptidoglycan
• Obligate intracellular parasites, require growth cofactors
(e.g., acetyl-CoA, NAD, ATP) provided by the cell
• Will not grow on artificial media
• Example Coxiella burnetii cause
Q-fever
Comparison of Chlamydiae & Rickettsiae
with Bacteria & Viruses
Bacteria
Chlamydia & Rickettsia Viruses
300-3000
350
15-350
Obligatory intracellular No
Yes
Yes
Nucleic acids
DNA & RNA
DNA & RNA
DNA OR RNA
Reproduction
Fission
Complex cycle with fission
Synthesis & assembly
Antibacterial sensitivity Yes
Yes
No
Ribosomes
Yes
Yes
No
Metabolic enzymes
Yes
Yes
No
Size (nm)
Energy production
Yes
No
No
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Rickettsiae
Taxonomy of Rickettsia
 Family: Ricketsiaceae
 Genus: Rickettsia, Coxiella, Bartonella
 Species
1. Rickettsia prowazekii (epidemic typhus)
2. Rickettsia typhi (endemic typhus)
3. Rickettsia rickettsii (spotted fever)
4. Bartonella quintana (trench fever)
5. Bartonella henselae (cat scratch fever)
6. Coxiella burnetii (Q fever)
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Rickettsiae
Gram-negative, coccobacilli, non-motile
 Best stained by Giemsa or Machiavello stains
Small (0.3-0.5 x 1-2 m) prokaryotic cells
 Contain both RNA & DNA & Multiply by binary fission
Obligate intracellular energy
 Except Bartonella quintana
They grow in tissue culture or yolk sac
 Except B. quintana: grow on blood agar under 5%CO2
All Rickettsial diseases are zoonotic
 Except Epidemic typhus and Trench fever
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Rickettsiae
• Transmitted through arthropod vector from reservoir
• Arthropods serves as both vector and reservoir
– Except C. burnetii does not transmitted through vector
• Cause skin rash, fever, headache & malaise
• ESCHAR, black ulcer developed at site of inoculation
– Except C. burnetii cause pneumonia, slow fever &
hepatitis
• Rickettsiae are susceptible to antiseptics, dryness & heat
– Coxiella resist pasteurization at 600C for 30 m
• Rickettsiae are sensitive to chloramphenicol & doxycycline
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Pathogenic Mechanism
Virulence factors：
Mechanism：
Endotoxin, Phospholipase A, slime layer
Bites or faeces of arthropod
Local lymph or micro blood vessels
(1st bacteremia)
Endothelial cells, micro blood vessels
in whole body
(2nd bacteremia)
Fever, rash, headache, etc
Targets:
Endothelial cells, micro blood vessels
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Rickettsial Diseases: 1-Typhus Group
Organism
Reservoir
Vector
Epidemic Typhus
Endemic Typhus
Rickettsia prowazekii
Human and flying squirrels
Lice borne
Rickettsia typhi
Rats and small rodent
Flea borne
Transmission Infected louse feces rubbed into
Inc. period
broken skin
8 days
Infected flea feces
rubbed into broken skin
7-14 days
Distribution
Worldwide
worldwide
Clinical
Sudden onset of fever & headache Gradual onset of Fever,
Rashes which spares the palms,
Headache, Rash
soles and face
Delirium/ stupor
Gangrene of hands or feet
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Rickettsial Diseases:2- Spotted fever Group
Rocky Mountain Spotted
Fever
Causative agent
Reservoir
Vector
Transmission
Geographic
distribution
Clinical
Mediterranean Sea
Spotted Fever
Rickettsia rickettsii
Dogs, rabbits, & wild rodents
Tick borne
Rickettsia conorii
Rodent
Tick borne
Wild and dog ticks bite
USA
Tick bite
Southern Europe,
Africa, Middle East
•Fever
•Severe Headache
•Rash
•Fever
•Conjunctival redness
•Sever headache
•Rash on wrests, ankles, soles,
palms initially and becomes
more generalized later
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Rickettsial Diseases: 3. Trench Fever
 Also called Five-day fever
 Causative agent: Bartonella quintana
 Reservoir: Human only
 Vector: Body human louse
 Transmission: Via feces of infected body lice being scratched
into the skin
 Geographic distribution:
 Temperate regions and high elevations in the tropics, including
South America
 Clinical
◦ Fever, Headache and Back pain
◦ It lasts for 5 days and recurs at 5 day intervals
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Rickettsial Diseases: 4- Q Fever
 Coxiella burnetii is the causative agent of Q fever. Q from Query
 Geographic distribution: Worldwide
 Clinical: Fever, Headache, Viral-like pneumonia, No Rash
– Complication of Q fever are Hepatitis and Endocarditis
 It can grow at pH 4.5 within phagolysosomes
 Coxiella burnetii is unique to the Rickettsiae Why???
 Because like Gram-positive spore formers
 This endospore confers properties to the bacteria that differ
from other Rickettsiae:
 This make the organism resistance to heat and drying
 Also extracellular existence
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Q Fever
Q fever is zoonotic and occupational disease
Reservoir: Cattle, sheep and goats
Non-arthropod vector transmission due to
Coxiella burnetii grows in Ticks and Cattle
The spores remain viable in;
– Dried tick feces deposited in cattle hide and
– Dried cow placentas following the birthing
• So Pneumonia occurred via inhalation of Spores via
– Airborne transmission of spore from hide or dried placenta or
– Via consumption of spore contaminated unpasteurized milk
•
•
•
•
•
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Laboratory diagnosis
•
•
•
•
•
Specimen: Blood and/or autopsy (Tissue)
Staining
Gram stain: gram negative coocobacilli (poorly stain)
Giemsa stain: purple
Isolation: difficult and dangerous
– The organism can be inoculated into tissue culture and grown over 4-7
days but this is very hazardous to personnel
• Serodiagnosis
1. Complement Fixation test (CFT)
Complement
Complement
Ag-Ab
Ag + Ab
Indicator system
RBCs-anti-RBCs
If the complement is free
Ag-Ab
+
Indicator system
RBCs-anti-RBCs
No lysis
Ag-Ab
Lysis
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Laboratory diagnosis
2.
Indirect Immuno-fluorescence reaction (IIFR)
• Rckettsial antigen + Patient’s serumn
Ag-Ab complex
• Add anti-antibody (Fluorescence) Ab-F
• Result in Ag-Ab-Ab-F which detected under fluorescence microscope
• The use of immunofluorescent antibodies to examine a biopsy can be diagnostic
3.
Weil-Fleix Reaction
• Some Rickettsia share antigenic characteristics with non-motile Proteus
vulgaris strain
• P. vulgaris strains that share these common antigens are designated OX-2, OX19, OX-K
• This is done by mixing patient’s serum (Antibody) and P. vulgaris strains (Antigen)
• Agglutination means positive test
• Results are shown in the Table
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Weil-Fleix Reaction
Disease
Weil-Fleix
OX-19
OX-2
OX-K
Rocky Mountain spotted fever +
Mediterranean Sea fever
+
+
+
-
Rickettsial pox
-
-
-
Epidemic typhus
Endemic typhus
+
+
-
-
-
-
Trench fever
-
-
-
Q fever
-
-
-
-
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Control
 Sanitary:
 Arthropod and rodent control
 Immunological:
 No vaccines are currently available
 Chemotherapeutic:
 Tetracycline or chloramphenicol are drugs of choice
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Chlamydiae
• Chlamydia is extremely tiny
• Gram-negative cocci bacteria, non-motile
• Have rigid cell wall
– Have outer membrane & Cytoplasmic membrane
– Lacking PDG and muramic acid
• Basophilic because stained blue by Giemsa stain
– Elementary bodies stain purple
– Reticulate body stain blue
– Inclusion body stain dark purple
• All share common complement fixing antigen
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Special Growth developmental Cycle
•Elementary body
•Infects host epithelial cell
•Taken by endocytosis
•Reticulate body
•Formed 1-2 hr latter
•Larger than EB
•Divided by Binary fission
•Inclusion body
•Aggregates of small particles
•Formed within 24-48 hrs
•Host cell rupture releasing EB
•Infects again new host cell
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Characteristics of elementary and
reticulate bodies of Chlamydia
ELEMENTARY BODY (EB)
RETICULATE BODY (RB)
Size 0.3 um (300 nm)
RNA:DNA content = 1.1
Infectious
Adapted for extracellular survival
Hemagglutinin present
Induces endocytosis
Metabolically inactive
Size 0.5 - 1.0 um (500-1000 nm)
RNA:DNA content = 3.1
Not infectious
Adapted for intracellular growth
Hemagglutinin absent
Does not induce endocytosis
Metabolically active
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Classification and Differentiation of Chlamydiae
Subgroup A
Subgroup B
Mammalian parasites
Bird parasites
Compact inclusions
Diffuse inclusions
Transmitted by contact
Transmitted by inhalation
Glycogen synthesized
Glycogen not synthesized
Folates synthesized (Sensitive)
Folates not synthesized (resistant)
Sensitive to D-cycloserine
Resistant to D-cycloserine
Restricted host range
Broadening of host range
• Chlamydia trachomatis
• Chlamydia psittaci
• Infects
non-ciliated
columnar • Chlamydia pneumoniae
epithelial cells (EYE and GENITAL)
Both infect LUNG
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SubgroupA: Chlamydia trachomatis
 Three biovars (biological variants):
1. Biovar Trachoma (15 Serologic types (A-K)
– A, B, Ba, C, D, Da, E, F, G, H, I ,Ia, J, Ja, K
– Serotypes A, B & C cause Trachoma
– Serotypes D-K cause inclusion conjunctivitis (Newborn),
Non-Gonococcal Urethritis, Cervicitis, Infant pneumonia
2. Biovar lymphogranuloma venereum, LGV (4 serologic
types) (L1, L2, L3,L4)
3. Biovar mouse
 Infects human non-ciliated columnar epithelial cells: Eye and
Genitals Except Biovar mouse
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a. Trachoma
 Severe form of chronic conjunctivitis
 Caused by C. trachomatis biovar Trachoma Serotypes A, B & C
 Transmission occurs by hand-to-hand transfer of infected
secretions to eye by infected articles (Towels)
 Can be also transmitted by droplets, contaminated clothing,
flies and by passage through an infected birth canal
 Infections occur most commonly in children
 Incubation period of 5 to 12 days
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a. Trachoma
 Conjunctivitis, pink eye, Eye discharge, Swollen eyelids,
Swelling of lymph nodes in front of the ears, corneal ulcer
 Producing scarring and deformity of the eyelids and corneal
vascularization and opacities which may lead to blindness
 Blindness develops slowly over 10-15 years
 Occurs worldwide primarily in areas of poverty & overcrowding
 500 million people are infected worldwide
 7 - 9 million people are blind as a consequence
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b. Inclusion conjunctivitis
 Collection of initial bodies in cytoplasm of conjunctival cells
 STD (Sexual Transmitted Disease) caused by C. trachomatis
biovar Trachoma Serotypes D-K
 Infection derives from mother to neonates during birth
 Mucopurulent yellow discharge and swelling of eyelids
 Develops 5-14 days after birth
 Newborns are given Erythromycin eye drops prophylactically
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c. Infant pneumonia
• Spread of Biovar Trachoma serotypes D-K through
nasolacrimal duct
• Common in babies
• Develops between 4-11 weeks of life
• Initially, the baby develops upper respiratory symptoms
followed by rapid breathing, cough and respiratory distress
• Diagnosed by presence of Chlamydial anti-IgM and/or
demonstration of C. trachomatis in clinical specimen
• Treated with oral erythromycin
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d. Urethritis (Male/Female)
 Caused by C. trachomatis Biovar Trachoma Serotypes D-K
 Urethritis –One cause of Non-Gonococcal Urethritis (NGU)
◦ NGU are most common caused by C. trachomatis & U. urealyticum
 STD and Majority (>50%) asymptomatic
 Symptoms : mucoid or clear urethral discharge, dysuria
 Incubation period unknown (5-10 days in symptomatic infection)
 Clinically, no difference between NGU and gonococcal urethritis
 Urethritis usually occurs as mixed infections
 Empirical therapy for urethritis
 Single dose of ceftriaxon (against Gonococci) followed by days
course of doxycycline or azithromycin (against NGU agents)
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e. Cervicitis and Pelvic Inflammatory Disease (PID)
 Cervicitis
•
•
•
•
•
◦ Majority (70%-80%) are asymptomatic
◦ Local signs of infection, when present, include:
 Mucopurulent endocervical yellow discharge
 Edematous cervical ectopy with erythema and friability
Infection can spread upwards to involve uterus, fallopian tubes
(Salpingitis) and ovaries
PID develops abnormal vaginal discharge or uterine bleeding,
pain with sexual intercourse, nausea , vomiting and fever
The most common symptom is lower abdominal pain
Infection by both N. gonorrhoeae & C. trachomatis is called PID
Treated by ceftriaxon followed by 14-days doxycycline
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f. Lymphogranuloma Venereum (LGV)
• STD
• Caused by C. trachomatis biovar lymphogranuloma venereum
L1, L2, L3 serotypes
• Starts with painless papule or ulceration on the genitals that heal
spontaneously
• The bacteria migrate to regional lymph nodes which enlarge over
the next 2 months
• These nodes become increasingly tender and may break open
and drain pus
• Fever, skin rash, nausea, and vomiting are often found
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Lab diagnosis
• Specimen:
– Sputum, Conjunctival scrapping, urethral discharge
or pus in LGV
• Satin:
– Giemsa’s stain
• Culture
– Cell culture treated with cycloheximide
• Non-culture tests
– Nucleic Acid Amplification Tests (NAATs)
– Non-Nucleic Acid Amplification Tests (Non-NAATs)
– Serology (Complement Fixation Test)
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Subgroup B: C. psittaci
• It infects > 130 species of birds
• It is the causative agent of;
– Psittacosis (parrots; parrot fever) or
– Ornithosis (Pigeons, chicken, ducks and turkey)
• Occupational disease for poultry workers
• Zoonotic disease (animal diseases)
• Infection occurred by inhalation of respiratory discharge,
feather or contaminated fecal material of birds
• Occurs after 1-3 weeks after exposure
• Infection results in atypical pneumonia
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Subgroup B: C. pneumoniae
• First recognized in 1983 as a respiratory pathogen, after
isolation from a student with pharyngitis
• Pneumonia or bronchitis, gradual onset of cough with
little or no fever. Less common presentations are
pharyngitis, laryngitis, and sinusitis
• Person-to-person transmission by respiratory secretions
• All ages at risk but most common in school-age children
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Mycoplasma & Ureplasma
 Smallest free-living organisms (150-250 nm)
 Pass through some bacterial filters
 Lack of a cell wall
 Three layer membranes
◦ Outer and inner: proteins and saccharide
◦ Middle: 1/3 cholesterol
 Multiple shapes: round, pear shaped & even filamentous
 Require complex media containing sterol
 Require sterols for growth and for membrane synthesis
 Grow slowly (3 weeks) by binary fission and produce "fried
egg" or “T strain” (tiny strain) colonies on agar plates
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Mycoplasma
• Mycoplasmas are spherical to filamentous cells with no cell
walls.
• Not affected by Penicillin or other Cell wall acting
antibiotics.
• The mycoplasmas are facultative anaerobes, except for M.
pneumoniae, which is a strict aerobe. Thus, they can
assume multiple shapes including round, pear shaped and
even filamentous. The mycoplasmas grow slowly by binary
fission and produce "fried egg" colonies on agar plates
• The mycoplasma all require
• sterols for growth and for
• membrane synthesis
• Two genera that infect humans: Mycoplasma and Ureaplasma
• They belong to Mycoplasmataceae
• There are many species of mycoplasmas
• Only four are recognized as human pathogens;
1. Mycoplasma pneumoniae
– Upper respiratory
pneumonia
tract
disease,
Tracheobronchitis,
atypical
2. Mycoplasma hominis
– Pyelonephritis, pelvic inflammatory disease, postpartum fever
3. Mycoplasma genitalium
– Nongonococcl urethritis (NGU)
4. Ureaplasma urealyticum
– NGU and may play a role in male fertility
– Isolation pathogen cultured in pH 6.0 media
– Requires 10% urea for growth
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Pathogenesis
 Adherence factors
 Adherence proteins are one of the major virulence factors
 Adhesin localizes at tips of the cells and binds to sialic acid residues on host
epithelial cells
 Toxic Metabolic Products




Intimate association provides an environment in which toxic metabolic products
accumulate and damage host tissues
Products of metabolism : hydrogen peroxide and superoxide -- oxidize host lipids
Inhibit host cell catalase
Immunopathogenesis



M. pneumoniae is a superantigen
Activate macrophages and stimulate cytokine production and lymphocyte
activation
Host factors contribute to pathogenesis
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M. pneumoniae
Need 10-20% Serum to culture in pH 7.8-8.0
Pathogenesis: P1 protein, capsule and saccharide
Spread by close contact via aerosolized droplets
Incubation period: 1-3 weeks
Cause tracheobronchitis, primary atypical pneumonia
– Fever, headache, sore throat and cough
– Initially cough is non-productive but occasionally
paroxysmal
• Antibodies play a role in controlling infection, particularly IgA
• Delayed type hypersensitivity
•
•
•
•
•
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