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MICR 3343 > Neisseria, Chlamydia and Treponema > Flashcards

Neisseria, Chlamydia and Treponema Flashcards

1
Q

Neisseria

A
  • gram-negative
  • diplococci
  • oxidase-positive
  • culture on selective Thayer Martin plates – chocolate agar (heated blood = brown)
  • can get false negatives in gram stain
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2
Q

N. gonorrhoeae (gonococcus)

A
  • found only in humans
  • gonorrhea
  • second most common venereal disease
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3
Q

Other clinical features of N. gonorrhoeae

A
  • cervicitis= relatively asymptomatic
  • pharyngitis= often asymptomatic
  • pelvic inflammatory disease PID= can be extremely severe, abdominal pain and fever, chronic pelvic pain
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4
Q

Dissemination - gonococci

A
  • gonococcal arthritis (septic)

- ophthalmia (highly contagious)

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5
Q

Therapy N. gonorrhoeae

A
  • B-lactamase-resistant cephalosporin *ceftriaxone

- resistant strains are common *produce b lactamases destroy penicillin

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6
Q

Prevention N. gonorrhoeae

A
  • no vaccine
  • safe sex
  • adequate contact and treatment of sex partners
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7
Q

Pathogenesis N. gonorrhoeae

A

-adhesion to genital epithelium
– outer membrane proteins (OMP) – pili
-tissue injury
– cell-wall lipopolysaccharide (LOS) – peptidoglycan
-antigenicity highly variable among strains - antibodies not protective

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8
Q

N. meningitis

A 
- Gram negative diplococci
within polymorphonuclear cells 
-meningococcal antigens
-Thayer Martin agar
-responds well to antibiotic therapy
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9
Q

Chlamydia trachomatis

A

-Small, gram-negative rods with no peptidoglycan layer in the cell wall
-Infects nonciliated columnar, cuboidal, and transitional epithelial cells
-Strict human intracellular parasite
-can infect newborns
-Two biovars associated with human disease
• Trachoma
• LGV

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10
Q

C. trachomatis diseases *Chlamydia

A

-is a common STD caused by C. trachomatis

• most infected people are asymptomatic and lack abnormal physical examination findings

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11
Q

C. trachomatis diseases *Lymphogranuloma venereum (LGV)

A

-caused by different serovars of the same bacterium, occurs commonly in the developing world,
• has more recently emerged as a cause of outbreaks of proctitis among men who have sex with men (MSM) worldwide

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12
Q

Virulence Chlamydia

A
  • Lipopolysaccharide antigen shared by Chlamydia and Chlamydophila species
  • Major outer membrane proteins are species-specific
  • Prevents fusion of phagosome with cellular lysosomes
  • Pathologic effects of trachoma caused by repeated infections
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13
Q

Epidemiology Chlamydia

A
  • Most common sexually transmitted bacteria in United States
  • Ocular trachoma primarily in North and sub-Sahara Africa, the Middle East, South Asia, South America
  • LGV highly prevalent in Africa, Asia, and South America
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14
Q

C. trachomatis growth cycle EB and RB

A
  • elementary bodies (EB) - infectious

* reticulate bodies (RB) - noninfectious

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15
Q

Diagnosis Chlamydia

A
  • Culture is highly specific but is relatively insensitive
  • Antigen tests (DFA, ELISA) are relatively insensitive
  • DNA amplification tests are the most sensitive and specific tests currently available
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16
Q

Treatment Chlamydia

A 
• LGV
- doxycycline or erythromycin
• Ocular or genital infections
- with azithromycin or doxycycline
• Newborn conjunctivitis or pneumonia - erythromycin
17
Q

Treatment CDC

A
  • A single dose of azithromycin or a week of doxycycline (twice daily)
  • Same treatment for HIV-positive persons
  • Persons should abstain from sexual intercourse for 7 days after single-dose antibiotics or until completion of a 7-day course of antibiotics, to prevent spreading the infection to partners
  • All sex partners should be evaluated, tested, and treated.
18
Q

Risk of reinfection chlamydia

A

-Women and men with chlamydia should be retested about three months after treatment of an initial infection, regardless of whether they believe that their sex partners were treated.

19
Q

Chlamydophila pneumoniae

A
  • Human pathogen
  • Sinusitis, pharyngitis, bronchitis, and pneumonia
  • Only a single serotype (TWAR)
  • Transmitted by respiratory secretions
20
Q

Chlamydophila pneumoniae Treatment

A

Treat with macrolides (erythromycin, azithromycin, clarithromycin), doxycycline, or levofloxacin

21
Q

Psittacosis (parrot fever)

A
  • Natural reservoir is virtually any species of bird
  • Also sheep, cows, goats, & humans
  • Sinusitis, pharyngitis, bronchitis, and pneumonia
  • Transmitted to humans by inhalation of dried excrement, urine, or respiratory secretions from psittacine birds (e.g., parrots, parakeets, macaws, cockatiels)
22
Q

Parrot fever symptoms

A
  • Can be asymptomatic
  • Headache, high fever, chills, malaise, and myalgias
  • Pneumonia: nonproductive cough, rales, consolidation
  • CNS involvement common, usually a headache, but encephalitis, convulsions, coma, and death may occur in severe, untreated cases
  • May have GI symptoms, such as nausea, vomiting, and diarrhea
  • Other systemic symptoms include carditis, hepatomegaly, splenomegaly, and follicular keratoconjunctivitis
23
Q

Parrot fever diagnosis

A

• Serology:
• 4X increase in titer, shown by the CF testing of paired
acute and convalescent phase sera, is suggestive of C. psittaci infection
• Must confirm the serologic diagnosis with species-specific MIF
• C. psittaci can be isolated in cell culture (e.g., with L cells)
after 5 to 10 days of incubation

24
Q

Treatment parrot fever

A
  • Treat with doxycycline or macrolides
  • Prevented only through the control of infections in domestic and imported pet birds
  • treat birds with chlortetracycline-HCL for 45 days
25
Q

Spirochetes

A 
• Gram-negative
• long, thin, helical, motile
• axial filaments – locomotion
– between peptidoglycan layer/ and outer membrane
(run parallel)
26
Q

Syphilis

A

• chronic
• slowly progressive
• three stages - primary
- secondary - tertiary

27
Q

Primary syphilis lesions - chancre

A
  • 10 to 60 days
  • area of ulceration and inflammation
  • many organisms • highly infectious
28
Q

Secondary (2-10 weeks later) syphilis

A
  • systemic spread
  • flu-like symptoms, then rash
  • many organisms • highly infectious
29
Q

Tertiary (several years later) syphilis

A 
• rare
• chronic inflammation - the destruction of any
organ/tissue - lesions in bone,
skin, other tissues
• neurosyphilis, cardiovascular syphilis
• few organisms
30
Q

Microbiological diagnosis Syphilis

A

• not cultureable
• dark field microscopy
– actively motile organisms
– brightly lit against dark backdrop – light shines at an angle
– reflected from thin organisms
– enters objective
• conventional light microscopy – light shines through
– NOT visualized
• fluorescence microscopy – antibody staining

31
Q

Secondary and Tertiary Syphilis - serology

A

screening method
- antibodies to cardiolipin
specific diagnosis
- antibodies to a treponemal antigen

32
Q

Treatment syphilis

A

• penicillin is effective

  • benzathine penicillin - early syphilis – penicillin G - congenital, late syphilis
  • no vaccine

MICR 3343 (10 decks)

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