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29 Cards in this Set
- Front
- Back
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Gram Neg
Obligate intracellular Unique development cycle* Ubiquitous |
Chlamydia
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Developmental cycle of Chlamydia
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1. Attachment and Entry
2. redistribution to nuclear periphery 3. early differentiation 4. Contact-dependent replication 5. detachment & asynchronous late differentiation 6. lysis and release of infctious progeny |
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0.2-0.4 diameter, um
1.21 density, g/ml late developmental stage + infectivity (-) interacellular multiplication No generation of ATP |
EB
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0.5 - 1.5 diameter, um
1.21 density, g/ml early developmental stage (-) infectivity + intracellular multiplication generates ATP |
RB
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Chlamydia genomics
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1.0-1.2 mB, 40% G+C, no repeat sequences
highly conserved genome ~900-1,100 genes, 800 shared in all species reductive evolution (gene loss) |
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true/false
Chlamydia can make some ATP |
False
Chlamydia cannot make ATP |
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True/ false
Chlamydia have peptidoglycan |
True
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Virulence Factors of Chlamydia
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1. Adherence: non-specific?
2. Tryptophan synthase 3. Type III secretion: molecular ‘syringes’ that inject virulence factors directly into the cytosol of infected cell 4. Cytotoxins related to clostridial cytotoxins |
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Primary infection: Inclusion conjunctivitis
Chronic infection: trachoma |
Ocular Chlamydia trachomatis
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Chlamydia induced newborn infections
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Ophthalmia neonatorum
Pneumonia syndrome of nexborn Treatment: Erythromycin, macrolides |
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Most common bacterial STI in US
10% of sexually active population infected Highest incidence in adolescents Predominantly caused by serovars D-K Most often asymptomatic or mild, hence unreported, untreated Men function as a reservoir |
Genital Chlamydia trachomatis
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Primary infections due to Genital Chlamydia trachomatis
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often mild or asymptomatic
Men: non-gonococcal urethritis Women: urethritis, cervicitis Treatment: azithromycin single dose or doxycycline for 7 days; altern.: erythromycin or ofloxacin or levofloxacin |
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Sequelae of chronic infection in women due to Genital Chlamydia trachomatis
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Pelvic Inflammatory Disease, PID
Ectopic pregnancy Infertility |
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Caused by serotypes L1-L3
Shallow ulcer on genitalia Invasive: Lymphadenopathy of inguinal lymph nodes Potentially severe complications Risk factor for HIV Current increases in LGV proctitis in women and homosexual men (In Netherlands and other European countries): recto-vaginal fistulae in women; substantial urethral destruction Treatment: doxycycline for 21 days; alternative: erythromycin |
Lymphogranuloma venereum
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Triad of urethritis, conjunctivitis and arthritis
Occurs in about 6% of individuals following chlamydial genital infection Chlamydial antigen can be detected in synovium Common in HLA B-27 haplotype |
Reiter’s Syndrome
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Sequelae of chronic infection
chronic bronchitis asthma exacerbation of COPD Sequelae of disseminated chronic infection reactive arthritis abdominal aortic aneurysm stroke MS, Alzheimer disease strongest association with atherosclerosis |
Chlamydia pneumoniae
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Psittacosis (ornithosis): C. psittaci zoonosis from infected birds
Flu-like illness to severe pneumonia Occupational hazard for people exposed to exotic birds or poultry, BGE engineers 30-95% infection rates in pigeons in Sarajevo, chicken in Beijing, duck farms in France, poultry farms in Germany, etc Rarely diagnosed in humans > vastly under-reported? Treatment: doxycycline, tetracycline B list bioweapon |
avian Chlamydia psittaci
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Gram-negative
Obligate intracellular NO developmental cycle Transmission primarily through arthropods (lice, fleas, ticks) |
Rickettsia
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Small cocci
Gram-negative cell wall, but stain poorly with GS Heterogeneous group Weil-Felix test based on antigenic relatedness of Rickettsia and Proteus sp. Slow growing: g= 8-12 hrs Induces own phagocytosis Cell-to-cell spread (à la Listeria) |
Rickettsiae
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What is the organism that casues Rocky Mountain Spotted Fever?
What is it's vector? |
R. rickettsii
Tick |
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Clinical diagnosis
History of tick bite or tick exposure Severe headache High fever (up to 105F) Rash Myalgia, photophobia, thrombocytopenia |
Rocky Mountain Spotted Fever
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Most severe rickettsial disease
Most prevalent rickettsial disease in US Common in tick season (spring-summer) |
Rocky Mountain Spotted Fever
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Coxiella burnetii
Grows in macrophage phagolysosomes Aerosol transmission Reservoir: domestic animals (livestock) People in slaughterhouses, dairy farms, etc., most susceptible Clinical symptoms Flu-like illness Chronic form associated with endocarditis Treatment Doxycycline, chloramphenicol Vaccine used in countries with high incidence Potential bioweapon |
Q fever
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wall-less pleiomorphic bacteria, evolved from Gram-positive by mutational loss
broad group, few pathogenic to humans fastidious organisms, difficult to manipulate in vitro |
Mycoplasma
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Require Cholesterol
Habitat: man, animals, plants, insects Can grow outside host cell |
Mycoplasma
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Virulence Determinants of Mycoplasma
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Hemolysins: alpha or beta hemolysin
Surface structures: organelles thought to mediate attachment to the surface of ciliated epithelial cells of the respiratory tract Capsule: polysaccharidic, may be involved in attachment or may have toxic effects |
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2 million cases yearly in US
persistent cough, malaise, fever community-acquired pneumonia diagnosis by serology and PCR leading cause of pneumonia in school-age children and young adults |
Mycoplasma Pneumoniae
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Immune Response to M. pneumoniae Infection
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Beneficial: early IgM, late IgG, IgA and CMI may play a role in protection
Deleterious: 50% develop cold agglutinins, IgM Abs that agglutinate erythrocytes at 4deg |
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Control of M. pneumoniae infection
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Diagnosis
difficult to grow (20 days) round mulberry colonies mostly serology Cold agglutinins, older test, poor sensitivity IgG or IgM by ELISA Treatment: doxycycline, ciproflaxin, erythromycin, azithromycin, levoflaxin No vaccine |
