MICR_042213_Chlamydia and Rickettsia Flashcards
What type of organism is chlamydia?
Obligate intracellular bacteria
What does chlamydia rely on the host for?
ATP
What are the 2 developmental stages of chlamydia?
Elementary bodies (EB) and Initital bodies (IB aka reticulate bodies (RB))
What is the difference between elementary bodies and the initial bodies of chlamydia?
ELEMENTARY BODIES (EB) - Small, non-multiplying form with a rigid bacteria-like cell wall. Infectious form - transmits from one cell/person to another. INITIAL BODIES: Larger, multiplying form that Lacks rigid wall; non-infectious form
What is the intracellular growth cycle of chlamydia?
1) EB induces host cell to phagocytose them, 2) Once inside the cell, the EB lose their cell wall, grow larger, and synthesize RNA to make Ibs, 3) IBs divide by binary fission; some of it is converted back to EB.
What are the 3 different types of chlamydia that is known to infect humans?
1) C. psittaci “parrot fever”, 2) C. pneumonia, 3) C. trachomatis
Of the 3 different types of chlamydia, which one has multiple serotypes?
C. trachomatis
How is C. Psittaci “parrot fever” transmitted?
it’s a natural parasite of birds; transmitted to humans via fecal matter
What does C. psittaci cause?
1) interstitial pneumonia - progressive scarring of lungs, 2) fever, 3) headache
How is C. pneumonia transmitted?
aerosol droplets
What does C. pneumonia cause?
causes atypical pneumonia or bronchitis, mostly in adults
What is unique about C. pneumonia’s pathology?
detected in atherosclerotic lesions; may play a role in coronary atherosclerosis
What are the 4 different serotypes of C. Trachomatis?
1) Serotype D-K 2) A, B, C, 3) L1, L2, L3
Which C. Trachomatis serotypes are more invasive?
Serotypes A, B, C, and L1, L2, L3
What does C. Trachomatis serotype D-K cause in ADULTS? How is it normally transmitted?
Nongonococcal urethritis, a common venereal disease transmitted via sexual contact
What are the symptoms that C. Trachomatis serotype D-K cause in adults?
Males/Females are normally ASYMPTOMATIC but both sexes can have more severe diseases involving the epididymis or fallopian tubes that can ultimately lead to sterility
What does C. Trachomatis serotype D-K cause in infants? How is it normally transmitted?
Inclusion Conjunctivitis and/or Infant Chlamydial Pneumonia. Transmitted via perinatal transmission (since the bacteria grows in the mother’s cervical cells).
What is infant chlamydial pneumonia?
caused by C. Trachomatis serotype D-K; is an extension of the ocular disease (inclusion conjunctivitis)
What does C. Trachomatis serotype A, B, C cause?
blindness - it is the leading cause of PREVENTABLE blindness
How is C. Trachomatis serotype A, B, C transmitted?
1) Mechanical (finger to the eye), 2) flies/poor hygiene (prevalent in tropical Africa and Asia)
What symptoms do C. Trachomatis serotype A, B, C cause?
chronic infection of conjunctiva, which can cause the eyelashes to grow inward, which can cause corneal scarring and blindness
What does C. Trachomatis serotype L1, L2, and L3 cause?
painless papule that progresses to a genital ulcerating vesicle and sometimes progress to a painful suppurating disease of regional lymph nodes
How is C. Trachomatis serotype A, B, C transmitted?
veneral disease - transmitted via sexual contact
How would you treat chlamydia?
Tetracycline and Azithromycin (antibiotics that can enter the cells)
How would you diagnose chlamydia?
Intraurethral or endocervical smears: test for specific serotypes (direct immunofluorescence to detect cytoplasmic inclusion bodies, PCR, seroassays)
In the serological tests, what’s the difference between the acute vs convalescent serum samples?
ACUTE: on-going symptoms, little or no antibody. CONVALESCENT: >5 d post symptoms, a lot of antibody produced
What is Rickettsia?
an intracellular pathogen that’s is normally parasites of arthropods (vector)
What does Rickettsia rely on the host for?
adapted to take up ATP, NAD, and other metabolites, but can make their own ATP
What is the typical life-cycle of Rickettsia?
1) induces host cell to phagocytose them, 2) multiplies via binary fission, 3) pathogens released via host cell lysis
How do you diagnose Rickettsia?
1) PCR, 2) Serological tests for specific antigens or antibody response, 3) immunohistologic detections
How do you treat Rickettsia?
Tetracycline and DTT (for lice control)
What are the different types of Rickettsia?
1) R. typhi, 2) R. rickettsii, 3) R. akari, 4) prowazekii (think TRAP)
What does rickettsia prowazekii cause?
primary epidemic typhus
How is rickettsia prowazekii transmitted?
human lice
What is the pathogenesis of rickettsia prowazekii?
replicates first in capillary endothelial cells and after ~10d there is an onset of fever and severe headache, followed by a rash 4-7d later
What is a complication of rickettsia prowazekii?
recovery does note eliminate rickettsia prowazekii; can resurface as BRILL-ZINSSER disease, especially if the immune response is compromised. Symptoms are the same as primary epidemic typhus
What is one additional test that you can do to test for rickettsia prowazekii?
liver function tests - usually elevated
What is unique about rickettsia typhi?
it is antigenically related to R. prowazekii
What does rickettsia typhi normally cause?
endemic murine typhus, a milder form of primary epidemic typhus
How is rickettsia typhi transmitted?
humans fleas from ground squirrels or rats
What does Rickettsia Rickettsii normally cause?
Rocky Mountain Spotted Fever
What are the symptoms of Rickettsia Rickettsii?
1) rash begins on the palms/soles and spreads rapidly to the trunk, 2) fever, headache, arthritic pains, abdominal pain with nausea and vomiting
How is Rickettsia Rickettsii normally transmitted?
humans forest ticks that infest many animals
What does Rickettsia akari normally cause?
Rickettsial pox (a rash that resembles that of chicken pox)
What are the symptoms of Rickettsia akari?
skin lesion at the site of the bite, followed by systemic symptoms (fevers, chills, headache, rash that resembles that of chicken-pox)
How is Rickettsia akari transmitted?
humans mouse mites (outbreaks are often confined to a single building/apartment complex)
What does coxiella burnetti cause?
Q fever
How is coxiella burnetti transmitted?
humans are infected via inhalation of spore-like c. burnetii that’s present on the placental tissue/carcasses of sheep, goat, cow cat (animal-animal transmission occurs via ticks); usually an occupational exposure
What are the symptoms of coxiella burnetti?
interstitial pneumonia, fever, headache, sometimes rash
How is coxiella burnetti normally diagnosed?
1) liver function tests – should be elevated, 2) serologic testing for specific antigens, 3) indirect immunofluorescence assay, 4) immunohistological staining , 5) PCR
How would you treat coxiella burnetti?
1) Doxycycline, 2) Quinolone antibiotics
What is erlichioses?
a tick-borne disease
What is erlichioses caused by? How are they different?
caused by two different obligate intracellular bacteria: 1) MONOCYTIC ehrlichiosis – infects monocytes 2) GRANULOCYTIC ehrlichiosis - infects granulocytes
What are some symptoms that ehrlichiosis cause?
1) fever, 2) lymphocytopenia (WBCs are being destroyed through infection), 3) elevated liver function tests due to liver damage
How would you treat ehrlichiosis?
tetracycline
What are the two strains of neisseria?
1) N. meningitidis 2) N. gonorrhoeae
What are the animal reservoir for neisseria?
none, humans are the only hosts.
What are some charcteristics of neisseria?
gram (-), diplococci
What conditions do neisseria grow best in?
rich medium, with 5-10% CO2
How would you test for the different strains of neisseria?
sugar fermentation tests
How do different strains of Neisseria ferment sugars differently?
1) N. gonorrhoeae – ferments glucose only, 2) N. meningitidis – ferments glucose and maltose, 3) N. lactamica (nonpathogenic) – ferments glucose, maltose, and lactose. NOTE that neisseria does NOT ferment sucrose!
How would you isolate NM and NG from other bacteria?
Thayer-martin selective medium
How would a Thayer-martin selective medium help isolate NM and NG from other bacteria?
it contains: 1) Vancomycin inhibits gram (+), 2) Colistin inhibit gram (-) enterics, 3) Nystatin is antifungal
How are pathogenic and non-pathogenic neisseria different in terms of growth conditions?
Non-pathogenic Neisseria do not require blood products in the medium, while pathogenic Neisseria do
T/F pathogenic and non-pathogenic neisseria are both oxidase positive
True. Both are oxidase positive
What are some virulence factors that neisseria produces and how does it contribute to their pathogenicity? (3)
1) PROTEASE - splits secretory IgA1, 2) PILI and outer membrane protiens (OMPs) contributes to colonization, 3) LOS (like LPS, but without the side-chains) - endotoxin; mediates resistance to serum bactericidal activity
Where does NM live?
nasopharynx
What are some virulence factors specific to NM?
1) CAPSULE has anti-phagocytic properties, 2) ENDOTOXIN - damages wall of small vessels
When does NM replicate?
only when it’s outside of cells. Once it is phagocytosed, it does not multiply
How is NM transmitted?
respiratory droplets (remember that it resides in the nasopharynx)
What is a complication of NM?
Waterhouse-Friderichsen Syndrome – meningococcemia causes adrenal failure circulatory collapse, shock, and rapid death
What is the Sub-saharan Meningitis Belt?
Largest burden of meningococcal meningitis in the world; caused by NM - Type A; due to overcrowded housing and large population displacements (pilgrimages and traditional markets)
How do you diagnose NM?
CLINICAL PICTURE: 1) URI, 2) high fever, 3) signs of meningitis, 4) Petechiae, followed by large areas of ecchymosis. CULTURE: blood, spinal fluid, nasopharyngeal specimens are cultured, examined for gram (-) diplococcic, followed by sugar fermentation testing
How do you treat NM?
I.V. penicillin or 3rd generation cephalosporins (ceftriaxone). Rifampin or Ciprofloxacin for those who have come into contact
Is there a vaccine for NM?
quadravalent vaccine for groups A, C, Y, and W135
Why isn’t there a vaccine for NM, type B?
the type B capsule is composed of sialic acid, which is not recognized by the C3b component of complement and does not stimulate recruitment of phagocytes
Both NM and NG produce an endotoxin. Which one is a major factor in the disease state?
NM
Where is NG normally found?
genitourinary tract
T/F NG has a capsule.
False. Only NM has a capsule
What are some virulence factors specific to NG?
PILI - promote sticking to epithelial cells and impairs phagocytosis by PMNs. NOTE: non-piliated strains are NOT virulent
How is NG transmitted? (2)
1) sex, 2) perinatal transmission
Perinatal transmission of NG can cause disease. How do you treat it?
ophthalamia neonatorium - can result in blindness in children. Treat with tetracycline or erythromycin ointment or dilute silver nitrate (1%)
What is the mechanism of pathogenesis of NG?
1) bacteria anchors to cells via their pili and penetrate through the cells to reach subendothelial connective tissue, 2) infection established within an hour of exposure, 3) Inflammation ensues, 4) Infection may spread to the epididymis or prostate in males and fallopian tubes in females
What are some of the symptoms of NG?
1) Yellow purulent urethral discharge (with burning sensations during urination) occurs
2) Asymptomatic carrier states are common and carriers can still transmit infection
What are some complications of NG?
1) Arthritis-dermatitis – infection spreads to ≥1 joints; skin lesions are present, 2) Chronic pelvic inflammatory disease – in females
How do you diagnose NG?
1) Clinical picture of discharge + history of exposure, 2) Stained smears of exudate show gram (-) diplococci within PMNs
How would you treat NG?
Intramuscular ceftriaxone; but must add 10d oral tetracycline, doxycycline, or azithromycin for chlamydia (assumption: chlamydial infection is present in gonnorhea cases)
What antibiotics is NG resistant to?
1) Pencillin, 2) Tetracycline, 3) some cephalosporins
What vaccines are available to treat NG?
none.
