48 Questions
What is the diameter of the elementary bodies (EB)?
0.2-0.3 microns
What is the reproductive form of Chlamydia?
Reticular bodies (RB)
What is the shape of the elementary bodies (EB)?
Spherical
What is the function of peptidoglycan in Chlamydia?
It provides structural support to the cell wall
Who discovered the presence of peptidoglycan in Chlamydia trachomatis?
Liechti et al.
What is the mode of reproduction in Reticular bodies (RB)?
Binary fission
What is the diameter of the Reticular bodies (RB)?
0.5-2 microns
What is the characteristic of the cell wall of Chlamydia?
It has a thin peptidoglycan layer
What is the primary way that Chlamydia trachomatis obtains energy?
From the host cell
What is the estimated number of people living in trachoma endemic areas?
142 million
What is the primary mode of transmission of trachoma?
Through flies, fomites, and touch
What is the estimated percentage of global-level antibiotic coverage in 2018?
50%
What is the name of the strategy used to combat trachoma?
SAFE
What is the name of the condition that can develop in infants when infected with Chlamydia trachomatis?
Inclusion blenorrhoea
What is the primary mode of transmission of genital chlamydiasis in men?
Sexual contact via STD
What is the incubation period for men infected with genital chlamydiasis?
7-28 days
What is the name of the disease caused by Rickettsia prowazekii?
Typhus
What is the primary mode of transmission of Rickettsia?
Arthropod vectors such as ticks, mites, and fleas
What is the name of the disease caused by Chlamydia psittaci?
Parrot fever
What is the typical duration of symptoms in patients infected with Chlamydia psittaci?
After 10 days
What is the name of the syndrome caused by Chlamydia in men?
Rieter's syndrome
What is the primary mode of transmission of Chlamydia psittaci?
Isolated from over 100 avian species
What is the characteristic feature of Rickettsiae?
All of the above
What is the primary difference between Typhus and Typhoid?
Symptoms
Chlamydia is a type of extracellular pathogen.
False
The elementary bodies of Chlamydia are metabolically active.
False
Chlamydia has a cell wall that lacks peptidoglycan.
False
Rickettsia is a type of gram-positive bacteria.
False
Chlamydia can only infect epithelial cells.
False
Chlamydia is a motile bacterium.
False
Reticular bodies of Chlamydia can divide by binary fission.
True
The diameter of elementary bodies of Chlamydia is approximately 0.5-2 microns.
False
Chlamydia trachomatis has a ATP-generating ability.
False
Trachoma is a public health problem in only 20 countries.
False
Trachomatous scarring is caused by infection of conjunctival epithelial cells only.
False
Trachoma is typically found in cold, humid climates.
False
Inclusion conjunctivitis is only found in neonatal form.
False
The global-level antibiotic coverage in 2018 was 100%.
False
Chlamydia can be transmitted through sexual contact and contaminated swimming pools.
True
The incubation period for men infected with genital chlamydiasis is typically less than 7 days.
False
Lymphogranuloma veneruum is a type of pneumonia caused by Chlamydia psittaci.
False
Rickettsia can be transmitted through contaminated food and water.
False
Typhus is caused by Salmonella typhi.
False
The symptoms of psittacosis typically appear within 5 days of infection.
False
Chlamydia trachomatis can cause epididymitis in women.
False
Rickettsiae are facultative intracellular pathogens.
False
Coxiella is transmitted through the bite of an infected arthropod.
False
Pediculus humanus corporis is the vector responsible for transmitting Typhoid fever.
False
Study Notes
Chlamydia and Rickettsia: Intracellular Lifestyle
Chlamydia
- Family: Chlamydia (previously included 2 genera: Chlamydia and Chlamydophila)
-
Species:
- C. trachomatis: ocular, genital
- C. psittaci: psittacosis
- C. pneumoniae: 10-20% of community-acquired pneumonia (CAP), cardiovascular disease
- Obligate intracellular pathogens: non-motile, coccoid bacilli that inhabit epithelial cells/macrophages
- Elementary bodies (EB): infectious form, metabolically inactive, electron dense, nucleoid, granular cytoplasm, spherical, approximately 0.2-0.3 microns in diameter
- Reticular bodies (RB): intracellular reproductive form, metabolically active, chromatin dispersed, approximately 0.5-2 microns in diameter, can divide by binary fission
- Energy parasites: lack ATP-generating ability, must obtain from host cell
Chlamydia Trachomatis
- Most common preventable cause of blindness: public health problem in 44 countries, responsible for blindness or visual impairment of about 1.9 million people
- Trachoma: infection of conjunctival epithelial cells, repeated clinical/subclinical infection and cell infiltration can cause cornea to cloud/scar
- SAFE strategy: Surgery, Antibiotics, Facial cleanliness, and Environmental improvement
- Inclusion conjunctivitis: neonatal form, adult form (STD, swimming pools)
- Genital chlamydiasis: urethritis, cervicitis, PID, infertility, ectopic pregnancy, premature delivery, postpartum fever, LGV
Chlamydia Psittaci
- Psittacosis/parrot fever: isolated from over 100 avian species, especially cockatiels and parakeets
- EB very resistant: can survive in feed for 2 months
- Clinical signs: range from non-apparent to flu-like to severe pneumonia (30-60 year olds)
- Risk groups: occupational disease, pigeon farmers, pet shop owners, veterinarians, poultry workers
Rickettsia
General Features
- Obligate intracellular pathogens: small coccoids or rods (0.3 by 1-2 microns)
- Fastidious: require embryonic eggs, tissue culture cells
- Structurally similar to Gram-negative bacteria: LPS and PG cell walls
- Multiply by binary fission: only in infected cells
- Transmitted by arthropod vectors: except Coxiella (Q fever)
Typhus
- Caused by Rickettsia prowazekii: arrives in Europe in 1489 via soldiers returning from Cyprus
- Transmitted by Pediculus humanus corporis: infected faeces
- Incubation: 7-14 days, high fever, chills, headache, may lead to coma
- Macular eruption: 5-6 days after onset
Typhus vs Typhoid
- Typhus: cough, headache, joint and muscle pain, nausea, chills, confusion, low blood pressure
- Typhoid: abdominal tenderness, agitation, bloody stool, chills, confusion, delirium, hallucinations, nose bleeds, and fatigue
Chlamydia and Rickettsia: Intracellular Lifestyle
Chlamydia
- Family: Chlamydia (previously included 2 genera: Chlamydia and Chlamydophila)
-
Species:
- C. trachomatis: ocular, genital
- C. psittaci: psittacosis
- C. pneumoniae: 10-20% of community-acquired pneumonia (CAP), cardiovascular disease
- Obligate intracellular pathogens: non-motile, coccoid bacilli that inhabit epithelial cells/macrophages
- Elementary bodies (EB): infectious form, metabolically inactive, electron dense, nucleoid, granular cytoplasm, spherical, approximately 0.2-0.3 microns in diameter
- Reticular bodies (RB): intracellular reproductive form, metabolically active, chromatin dispersed, approximately 0.5-2 microns in diameter, can divide by binary fission
- Energy parasites: lack ATP-generating ability, must obtain from host cell
Chlamydia Trachomatis
- Most common preventable cause of blindness: public health problem in 44 countries, responsible for blindness or visual impairment of about 1.9 million people
- Trachoma: infection of conjunctival epithelial cells, repeated clinical/subclinical infection and cell infiltration can cause cornea to cloud/scar
- SAFE strategy: Surgery, Antibiotics, Facial cleanliness, and Environmental improvement
- Inclusion conjunctivitis: neonatal form, adult form (STD, swimming pools)
- Genital chlamydiasis: urethritis, cervicitis, PID, infertility, ectopic pregnancy, premature delivery, postpartum fever, LGV
Chlamydia Psittaci
- Psittacosis/parrot fever: isolated from over 100 avian species, especially cockatiels and parakeets
- EB very resistant: can survive in feed for 2 months
- Clinical signs: range from non-apparent to flu-like to severe pneumonia (30-60 year olds)
- Risk groups: occupational disease, pigeon farmers, pet shop owners, veterinarians, poultry workers
Rickettsia
General Features
- Obligate intracellular pathogens: small coccoids or rods (0.3 by 1-2 microns)
- Fastidious: require embryonic eggs, tissue culture cells
- Structurally similar to Gram-negative bacteria: LPS and PG cell walls
- Multiply by binary fission: only in infected cells
- Transmitted by arthropod vectors: except Coxiella (Q fever)
Typhus
- Caused by Rickettsia prowazekii: arrives in Europe in 1489 via soldiers returning from Cyprus
- Transmitted by Pediculus humanus corporis: infected faeces
- Incubation: 7-14 days, high fever, chills, headache, may lead to coma
- Macular eruption: 5-6 days after onset
Typhus vs Typhoid
- Typhus: cough, headache, joint and muscle pain, nausea, chills, confusion, low blood pressure
- Typhoid: abdominal tenderness, agitation, bloody stool, chills, confusion, delirium, hallucinations, nose bleeds, and fatigue
Learn about the impact and aetiology of Chlamydia and Rickettsia, including their unique life cycle and intracellular survival. Understand the characteristics of these bacteria and their effects on human health.
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