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M3 l Microbiology > B2 G&D III lec3 : Infectious cervicitis > Flashcards

B2 G&D III lec3 : Infectious cervicitis Flashcards

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Biology 101 flashcards
1
Q

What are the important properties of Neisseria gonorrhoeae?

A
  • Are gram-negative cocci that resemble paired kidney beans
  • has no polysaccharide capsule
  • has multiple serotypes
  • contain endotoxin in their outer membrane

-Gonococci have three outer membrane proteins (proteins I, II, and III)

-Neisseriae are oxidase-positive (i.e., they possess the enzyme cytochrome c)

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2
Q

What determines the multiple serotype in N.gonorrhoeae?

A

based on the antigenicity of its pilus protein

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3
Q

What does the endotoxin contain in nisseriae?

A

consist of lipooligosaccharide (LOS), in contrast to the lipopolysaccharide (LPS) found in enteric gram-negative rods. Both LPS and LOS contain lipid A.

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4
Q

What is the role of protein II?

A

Protein II plays a role in attachment of the organism to cells and varies antigenically as well

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5
Q

What inhibits the growth of Neisseriae?

A

inhibited by toxic trace metals and fatty acids found in certain culture media (e.g., blood agar plates).

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6
Q

Which culture is used for N. gonorrhoeae?

A

“chocolate” agar containing blood heated to 80°C, which inactivates the inhibitors.

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7
Q

Gonococci cause disease only in______

A

Humans

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8
Q

How is Gonococci transmitted?

A

usually transmitted sexually; newborns can be infected during birth

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9
Q

Why sexual transmission favors the survival of gonococcus?

A

Because it’s quite sensitive to dehydration and cool conditions

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10
Q

What is the most common source of infection in Gonococci?

A

Genital tract infection

  • NB: anorectal and pharyngeal infections are important sources as well.
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11
Q

What is the role of Piliated gonococci?

A

They are important virulent factor that mediate attachment to mucosal cell surfaces and are antiphagocytic.

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12
Q

What are the 2 virulence factors found in the cell wall of N.gonorrhoeae?

A

endotoxin and the outer membrane proteins

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13
Q

What is the function of IgA protease in N.gonorrhoeae?

A

hydrolyze secretory IgA, which could otherwise block attachment to the mucosa

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14
Q

Who are the main host defense against gonococci and what they do?

A
  1. Antibodies (IgA and IgG),
  2. Complement
  • Antibody-mediated opsonization and killing within phagocytes occur.
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15
Q

Does Gonococci have capsules?

A

No

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16
Q

Why repeated gonococcal infections occur?

A

primarily as a result of antigenic changes of pili and the outer membrane proteins

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17
Q

Where does the Gonococci infect?

A

the mucosal surfaces (e.g., the urethra and vagina).

  • Certain strains of gonococci cause disseminated infections more frequently than others.
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18
Q

What is DGI stand for?

A

Disseminated Gonococcal Infection

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19
Q

What is DGI resistant to?

A

resistant to the killing by antibodies and complement “serum resistance”

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20
Q

What plays a role in the “serum resistance”?

A

The presence of a porin protein (porin A) in the cell wall, which inactivates the C3b component of complement

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21
Q

The occurrence of DGI depends on what?

A

The occurrence of a disseminated infection is a function not only of the strain of gonococcus but also of the effectiveness of the host defenses

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22
Q

Who get infected by DGI?

A

Persons with a deficiency of the late-acting complement components

(C6–C9) are at risk for disseminated infections, as are women during menses and pregnancy.

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23
Q

Gonorrhea is usually symptomatic in ______but often asymptomatic in ________

A

Men ; women

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24
Q

What does Gonococci cause?

A

both localized infections, usually in the genital tract, and disseminated infections (via the bloodstream) with seeding of various organs.

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25
Q

How is Gonorrhea characterized in men?

A

by urethritis accompanied by dysuria and purulent discharge. Epididymitis can occur

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26
Q

How is Gonorrhea characterized in women?

A

infection is located primarily in the endocervix, causing a purulent vaginal discharge and intermenstrual bleeding (cervicitis).

27
Q

What is a complication found in women with Gonorrhea ? Explain.

A

ascending infection of the uterine tubes (salpingitis, pelvic inflammatory disease “PID”)

—-> can result in scarring of the tubes resulting in sterility or ectopic pregnancy.

28
Q

What is the manifestations of DGI?

A

arthritis, tenosynovitis, or painless pustules in the skin.

29
Q

How is infected by Anorectal ?

A

chiefly in women and homosexual men. bloody or purulent discharge (proctitis) can occur. In the throat, pharyngitis occurs, but many patients are asymptomatic.

30
Q

What is Ophthalmia neonatorum?

A

Occurs in newborn infants; it’s a result of gonococcal infection acquired from the mother during passage through the birth canal. Declined nowadays due to prophylactic antibiotic ointment applied shortly after birth.

31
Q

What is Gonococcal conjunctivitis?

A

A result of the transfer of organisms from the genitals to the eye ; also occurs in adults

32
Q

What are other sexual diseases that coexist with gonorrhea?

A

STDs e.g., syphilis and nongonococcal urethritis caused by Chlamydia trachomatis
can coexist with gonorrhea and the patient should be tested for them.

33
Q

What is sufficient diagnosis of gonorrhea in men?

A

Gram staining

34
Q

What is found in GS of gonorrhea in men?

A

gram-negative diplococci within PMNs (polymorph nuclear leukocytes) in a urethral discharge specimen

35
Q

Why gram stain is not performed for women with gonorrehea?

A

the use of Gram stain alone on cervical specimens can be falsely positive because of the presence of gram-negative diplococci in the normal flora

36
Q

Where is gonorrhea cultured?

A

Thayer-Martin medium

37
Q

What are the samples taken for Thayer-Martin medium

A

urethra and cervix ( mucosal sites)

38
Q

What does TM agar contain?

A

chocolate agar containing antibiotics (vancomycin, colistin, trimethoprim, and nystatin) to suppress the normal flora.

39
Q

Which specimens can be used without antibiotics in chocolate agar?

A

Specimens from sterile sites, such as blood or joint fluid, can be cultured on chocolate agar without antibiotics because there is no competing normal flora.

40
Q

What is sufficient finding that identify the isolate as a member of the genus Neisseria ?

A

The finding of an oxidase-positive colony composed of gram-negative diplococci

41
Q

What is the test of choice for Chlamydia trachomatis and Neisseria gonorrhoeae diagnosis?

A

Nucleic acid amplification tests (NAAT)

42
Q

What does Chlamydia trachomatis cause?

A

eye (conjunctivitis, respiratory (pneumonia),
and genital tract lymphogranuloma venereum) infections.

43
Q

Infection of C. trachomatis is also associated with which autoimmune disease?

A

Reiter’s syndrome

44
Q

State the important properties of Chlamydiae trachomatis

A
  • are obligate intracellular bacteria.
  • lack the ability to produce sufficient energy to grow independently and therefore can grow only inside host cells.
  • rigid cell wall but do not have a typical peptidoglycan layer
  • Don’t stain by gram

-All chlamydiae share a group-specific lipopolysaccharide antigen.

-They also possess species-specific and immunotype-specific antigens (proteins),C. trachomatis has at least 15 immunotypes (A–L).

45
Q

When does the replication cycle of Chlamydiae begin?

A

when the extracellular, metabolically inert, “sporelike” elementary body enters the cell.

46
Q

Explain the replication cycle of Chlamydia trachomatis

A

• Reorganizes into a larger, metabolically active “reticulate body”.

• The latter undergoes repeated cycles of binary fission to form daughter reticulate bodies, which then develop into elementary bodies, which are released from the cell.

• Within cells, the site of replication appears as an “inclusion body”.

• These cytoplasmic inclusion bodies are useful in the identification of these organisms in the clinical laboratory as they can be stained and visualized microscopically.

• The “cytoplasmic inclusion bodies”, which are characteristic of chlamydial infections, consists of many daughter reticulate and elementary bodies.

47
Q

How is C. trachomatis transmitted?

A

infects only humans and is usually transmitted by close personal contact (e.g., sexually or by passage through the birth canal)

48
Q

How is C.trachomatis transmitted in trachoma?

A

by finger-to-eye or fomiteto-eye contact

49
Q

What happens with patients with a sexually transmitted disease?

A

are co-infected with both C. trachomatis and Ne. gonorrhoeae in approximately 10% to 30% of cases.

50
Q

Which cells do Chlamydiae infect?

A

epithelial cells of the mucous membranes

51
Q

What does type A , B & C cause?

A

trachoma, a chronic conjunctivitis that may lead to blindness but causes no systemic illness.

52
Q

What happens with types D-K in men?

A

common cause of nongonococcal urethritis (NGU) which is characterized by dysuria and a watery,

nonpurulent urethral discharge. The discharge may be slight, detectable only by staining of underwear overnight. This infection may progress to epididymitis, prostatitis.

53
Q

What happens with types D-K in women?

A

cervicitis develops and may progress to salpingitis and pelvic inflammatory disease (PID). Repeated episodes of salpingitis or PID can result in infertility or ectopic pregnancy.

54
Q

What happens with types D-K in Infants born to infected mothers ?

A

often develop mucopurulent conjunctivitis (neonatal inclusion conjunctivitis) 7 to 12 days after delivery, and some develop chlamydial pneumonitis 2 to 12 weeks after birth.

55
Q

What is Chlamydial conjunctivitis?

A

occurs in adults as a result of the transfer of organisms from the genitals to the eye

56
Q

Patients with genital tract infections caused by C. trachomatis have a high incidence of_________

A

Reiter’s syndrome

57
Q

What does type L1-L3 cause?

A

lymphogranuloma venereum, a
sexually transmitted disease with lesions on genitalia and lymph nodes, systemic symptoms such as fever, malaise, chills, and/or myalgia are common.

58
Q

What does infection by C. trachomatis lead to?

A

leads to formation of antibodies and cell-mediated reactions but not to resistance to reinfection or elimination of organisms.

59
Q

Where does type D-K occur?

A

cause genital tract infections, which are occasionally transmitted to the eyes or the respiratory tract.

60
Q

What is Reiter’s syndrome?

A

an autoimmune disease caused by antibodies formed against C. trachomatis cross-reacting with antigens on the cells of the urethra, joints, and uveal tract.

61
Q

Which stain is not useful in Chlamydiae?

A

Gram stain

62
Q

cytoplasmic inclusions of chlamydiae can be seen with which method/s?

A

can be seen with special stains (e.g., Giemsa stain) or by immunofluorescence. Chlamydiae can be grown in cell cultures.

63
Q

What forms in culture of C. trachomatis?

A

forms inclusions containing glycogen visualized by staining with iodine.

64
Q

Which test is widely used to diagnose chlamydial sexually transmitted disease by urine?

A

Nucleic acid amplification tests (NAATs)

M3 l Microbiology (7 decks)

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