B2 G&D III lec3 : Infectious cervicitis Flashcards
What are the important properties of Neisseria gonorrhoeae?
- 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)
What determines the multiple serotype in N.gonorrhoeae?
based on the antigenicity of its pilus protein
What does the endotoxin contain in nisseriae?
consist of lipooligosaccharide (LOS), in contrast to the lipopolysaccharide (LPS) found in enteric gram-negative rods. Both LPS and LOS contain lipid A.
What is the role of protein II?
Protein II plays a role in attachment of the organism to cells and varies antigenically as well
What inhibits the growth of Neisseriae?
inhibited by toxic trace metals and fatty acids found in certain culture media (e.g., blood agar plates).
Which culture is used for N. gonorrhoeae?
“chocolate” agar containing blood heated to 80°C, which inactivates the inhibitors.
Gonococci cause disease only in______
Humans
How is Gonococci transmitted?
usually transmitted sexually; newborns can be infected during birth
Why sexual transmission favors the survival of gonococcus?
Because it’s quite sensitive to dehydration and cool conditions
What is the most common source of infection in Gonococci?
Genital tract infection
- NB: anorectal and pharyngeal infections are important sources as well.
What is the role of Piliated gonococci?
They are important virulent factor that mediate attachment to mucosal cell surfaces and are antiphagocytic.
What are the 2 virulence factors found in the cell wall of N.gonorrhoeae?
endotoxin and the outer membrane proteins
What is the function of IgA protease in N.gonorrhoeae?
hydrolyze secretory IgA, which could otherwise block attachment to the mucosa
Who are the main host defense against gonococci and what they do?
- Antibodies (IgA and IgG),
- Complement
- Antibody-mediated opsonization and killing within phagocytes occur.
Does Gonococci have capsules?
No
Why repeated gonococcal infections occur?
primarily as a result of antigenic changes of pili and the outer membrane proteins
Where does the Gonococci infect?
the mucosal surfaces (e.g., the urethra and vagina).
- Certain strains of gonococci cause disseminated infections more frequently than others.
What is DGI stand for?
Disseminated Gonococcal Infection
What is DGI resistant to?
resistant to the killing by antibodies and complement “serum resistance”
What plays a role in the “serum resistance”?
The presence of a porin protein (porin A) in the cell wall, which inactivates the C3b component of complement
The occurrence of DGI depends on what?
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
Who get infected by DGI?
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.
Gonorrhea is usually symptomatic in ______but often asymptomatic in ________
Men ; women
What does Gonococci cause?
both localized infections, usually in the genital tract, and disseminated infections (via the bloodstream) with seeding of various organs.
How is Gonorrhea characterized in men?
by urethritis accompanied by dysuria and purulent discharge. Epididymitis can occur
How is Gonorrhea characterized in women?
infection is located primarily in the endocervix, causing a purulent vaginal discharge and intermenstrual bleeding (cervicitis).
What is a complication found in women with Gonorrhea ? Explain.
ascending infection of the uterine tubes (salpingitis, pelvic inflammatory disease “PID”)
—-> can result in scarring of the tubes resulting in sterility or ectopic pregnancy.
What is the manifestations of DGI?
arthritis, tenosynovitis, or painless pustules in the skin.
How is infected by Anorectal ?
chiefly in women and homosexual men. bloody or purulent discharge (proctitis) can occur. In the throat, pharyngitis occurs, but many patients are asymptomatic.
What is Ophthalmia neonatorum?
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.
What is Gonococcal conjunctivitis?
A result of the transfer of organisms from the genitals to the eye ; also occurs in adults
What are other sexual diseases that coexist with gonorrhea?
STDs e.g., syphilis and nongonococcal urethritis caused by Chlamydia trachomatis
can coexist with gonorrhea and the patient should be tested for them.
What is sufficient diagnosis of gonorrhea in men?
Gram staining
What is found in GS of gonorrhea in men?
gram-negative diplococci within PMNs (polymorph nuclear leukocytes) in a urethral discharge specimen
Why gram stain is not performed for women with gonorrehea?
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
Where is gonorrhea cultured?
Thayer-Martin medium
What are the samples taken for Thayer-Martin medium
urethra and cervix ( mucosal sites)
What does TM agar contain?
chocolate agar containing antibiotics (vancomycin, colistin, trimethoprim, and nystatin) to suppress the normal flora.
Which specimens can be used without antibiotics in chocolate agar?
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.
What is sufficient finding that identify the isolate as a member of the genus Neisseria ?
The finding of an oxidase-positive colony composed of gram-negative diplococci
What is the test of choice for Chlamydia trachomatis and Neisseria gonorrhoeae diagnosis?
Nucleic acid amplification tests (NAAT)
What does Chlamydia trachomatis cause?
eye (conjunctivitis, respiratory (pneumonia),
and genital tract lymphogranuloma venereum) infections.
Infection of C. trachomatis is also associated with which autoimmune disease?
Reiter’s syndrome
State the important properties of Chlamydiae trachomatis
- 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).
When does the replication cycle of Chlamydiae begin?
when the extracellular, metabolically inert, “sporelike” elementary body enters the cell.
Explain the replication cycle of Chlamydia trachomatis
• 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.
How is C. trachomatis transmitted?
infects only humans and is usually transmitted by close personal contact (e.g., sexually or by passage through the birth canal)
How is C.trachomatis transmitted in trachoma?
by finger-to-eye or fomiteto-eye contact
What happens with patients with a sexually transmitted disease?
are co-infected with both C. trachomatis and Ne. gonorrhoeae in approximately 10% to 30% of cases.
Which cells do Chlamydiae infect?
epithelial cells of the mucous membranes
What does type A , B & C cause?
trachoma, a chronic conjunctivitis that may lead to blindness but causes no systemic illness.
What happens with types D-K in men?
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.
What happens with types D-K in women?
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.
What happens with types D-K in Infants born to infected mothers ?
often develop mucopurulent conjunctivitis (neonatal inclusion conjunctivitis) 7 to 12 days after delivery, and some develop chlamydial pneumonitis 2 to 12 weeks after birth.
What is Chlamydial conjunctivitis?
occurs in adults as a result of the transfer of organisms from the genitals to the eye
Patients with genital tract infections caused by C. trachomatis have a high incidence of_________
Reiter’s syndrome
What does type L1-L3 cause?
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.
What does infection by C. trachomatis lead to?
leads to formation of antibodies and cell-mediated reactions but not to resistance to reinfection or elimination of organisms.
Where does type D-K occur?
cause genital tract infections, which are occasionally transmitted to the eyes or the respiratory tract.
What is Reiter’s syndrome?
an autoimmune disease caused by antibodies formed against C. trachomatis cross-reacting with antigens on the cells of the urethra, joints, and uveal tract.
Which stain is not useful in Chlamydiae?
Gram stain
cytoplasmic inclusions of chlamydiae can be seen with which method/s?
can be seen with special stains (e.g., Giemsa stain) or by immunofluorescence. Chlamydiae can be grown in cell cultures.
What forms in culture of C. trachomatis?
forms inclusions containing glycogen visualized by staining with iodine.
Which test is widely used to diagnose chlamydial sexually transmitted disease by urine?
Nucleic acid amplification tests (NAATs)
