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24 Cards in this Set
- Front
- Back
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Name the Bug
Small Obligate-Intercellular Bacteria Unable to grow in cell-free media Unable to metabolize glucose or amino acids Uses Host ATP Lives in Cytosol – No vacuole Weakly Gram-negative Stain best with Giemsa Stain Spread by Arthropod Vectors Ticks, Lice, Fleas, Mites |
Rickettsiae
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O. tsutsugamushi causes
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Scrub Typhus
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Spotted Fever Group
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R. rickettsii → RMSF
R. acari → Rickettsialpox R. africae → African Tick Bite Fever R. conorii → Boutonneuse ~ 20 Other Human Pathogens |
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Typhus Group
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R. prowazekii → Typhus
R. typhi → Murine Typhus |
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Organism – R. rickettsii
Vector – Tick Dermacentor variabilis – Eastern USA D. andersoni – Western USA Rhipicephalus sanguineus – Mexico A. cajennese – Central & South America Host Wild Rodents, Dogs Spring - Early Summer Disease |
Rocky Mountain Spotted Fever
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What are the common clinical features of Rocky Mountain Spotted Fever?
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Prodrome – Headache, Fever, Myalgia
Rash – Day 3 to 5 Wrists, Ankles → Trunk Maculo-Petechial 4% Progress to Gangrene Scrotal gangrene Delirium, Headache, Meningismus Abdominal Pain, Diarrhea – 1/3 ARDS Death – 20% untreated |
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Treameant for RMSS
Ricket Rickettsiae |
Tetracycline
Doxycycline 100 mg q 12h Chloramphenicol 50-75 mg/kg/day Doxycycline – Preferred Drug Case Fatality Rate – 1.4% versus 7.7% |
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What suggests RMSF
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Acute Onset
Fever & Chills Headache Prostration Season of the Year Late Spring – Early Summer Possible Tick Exposure Rash – (usually in the first week) Beginning on wrists/arms |
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Sennetsu Fever
Human Monocyte Ehrlichiosis (HME Human Granulocyte Ehrlichiosis (HGE) |
Ehrlichial Diseases
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Belong to family Anaplasmataceae. No longer in family Rickettsiaceae. Intracellular bacteria that parasitize blood cells – primarily Granulocytes or Monocytes. They live in phagocytic vacuole, unlike Rickettsia that live free in the cytoplasm,
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Ehrlichia/Anaplasma
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E. chaffeensis
SE & Midwest USA Anaplasma phagocytophilum New England & North Central USA Europe E. ewingii Midwest USA Neorickettsia sennetsu Japan & Malaysia |
Human Ehrlichia pathogens
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Epi of Eyrchiosis
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Tick Vector
Ixodes scapularis A. phagocytophilum Amblyomma americanum E. chaffeensis E. ewingii Peak Disease – Early, Mid-Summer Disease Incidence ↑ with Age Most patients recall a tick exposure |
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Treatment of Ehrlichiosis/Anaplamosis
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Treatment
Doxycycline Very Rapid Response Rifampin (if unable to take doxycycline) |
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What Should Suggest Ehrlichia or Anaplasma?
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Abrupt Onset
Fever, Chills, Sweats, Malaise Laboratory Abnormalities Falling WBC Falling Platelet Count Moderate LFT Abnormalities Late Spring or Summer Tick Exposure |
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Coxiella burnetii
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Another intracellular organism. Lives in phagocytic vacuole. Commonest cause of VD in USA.
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Small poorly staining bacteria
Reproduce in phagasomes of host cells Survive outside cells for long time Unlike Rickettsia Infection by aerosol of parturient farm animals High concentration in placenta Has been spread by birthing cat Disease is Q Fever |
Properties of Coxiella
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Flu-like Illness
Usually mild Serious Disease Pneumonia, Hepatitis, Endocarditis Causes granulomas in liver Diagnosis by Serology Treatment is with Tetracycline |
Q Fever
(Coxiella) |
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Obligate Intracellular Bacteria
Requires Host ATP Transmitted Host → Host No Vector Life Cycle Involves 2 Forms |
Chlamydia
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Elementary Body
Infectious Form Attaches to Cell Membranes Engulfed by Endocytosis Reticulate Body Forms inside vacuole Multiplies by division Forms large inclusion Condenses to EB Cell ruptures releasing EB |
Chlamydia pathogenesis
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C. trachomatis
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Numerous serotypes causing different diseases - mainly venereal disease
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Trachoma (Serotypes A,B,C)
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Common cause of blindness in Middle East
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Urethritis or Cervicitis
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Very common VD
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Chlamydia – Urethritis/Vaginitis Treatment?
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Azithromycin – 1 Gram – Single Dose
Treatment of Choice Other Treatment Tetracycline – 100 mg bid for 7 days Erythromycin in Pregnancy |
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What Should Suggest Chlamydia?
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Thin, Watery Discharge
Urethra Cervix Current STD or History of STDs Pelvic Inflammatory Disease |
