PATHOGENESIS
AND CLINICAL PICTURE: Gonorrhea is a sexually transmitted
disease. The pathogens penetrate into the urogenital mucosa, causing
a local purulent infection. In men, the prostate and epididymis can
also become infected. In women, the gonococci can also cause
salpingitis, oophoritis, or even peritonitis. Gonococci reaching the
conjunctival membrane may cause a purulent conjunctivitis, seen
mainly in newborn children. Gonococci can also infect the rectal or
pharyngeal mucosa. Hematogenously disseminated gonococci may also
cause arthritis or even endocarditis.
DETERMINANTS
OF THE PATHOGENICITY OF GONOCOCCI: Attachment pili on the
surface and the outer membrane protein are responsible for adhesion
to cells of the urogenital tract. It also directs the invasion
process by means of endocytosis. Immune defenses against granulocytes
are based on the outer membrane porin that prevents the phagosome
from fusing with lysosomes, resulting in the survival, and
proliferation of phagocytosed gonococci in granulocytes.
The
lipo-oligosaccharide (LOS) in the outer membrane is responsible for
resistance to complement (serum resistance) as well as for the
inflammatory tissue reaction in a manner analogous to the more
complexly structured LPS of enterobacteria.
Gonococci
can capture iron from the siderophilic proteins lactoferrin and
transferrin, accumulating it inside the bacterial cells to facilitate
their rapid proliferation.
An
IgA1 protease produced by the gonococci hydrolyzes secretory
antibodies in the mucosal secretions. The pronounced antigen
variability of the attachment pili and the Opa protein make it
possible for gonococci to thwart specific immune defense mechanisms
repeatedly.
DIAGNOSIS:
The method of choice is detection of the pathogens by means of
methylene blue and gram staining and culturing. Gonococci are
sensitive in cultures and the material must be used immediately after
they are obtained to inoculate. Thayer-Martin blood agar with
antibiotics added to eliminate accompanying flora, on which medium
the cultures are then transported to the laboratory. The
identification procedure involves both morphology and biochemical
characteristics. Techniques developed recently utilize
immunofluorescence or coagglutination methods utilizing monoclonal
antibodies to the main protein of the outer membrane, Por. Direct
detection in pus and secretion samples is possible using an enzymatic
immunosorbence test or detection of gonococcus-specific DNA sequences
coding for rRNA using a gene probe.
THERAPY:
The agent of choice used to be penicillin G. In recent years,
however, the percentage of penicillinase-producing strains has
increased considerably all over the world. For this reason,
third-generation cephalosporins are now used to treat uncomplicated
cases of gonorrhea. They are applied in a single dose (e.g.,
ceftriaxone, 250–500 mg I.M.). Good results have also been reported
with single-dose oral application of fluorinated 4-quinolones (e.g.,
0.5 g ciprofloxacin or 0.4 g ofloxacin).
RELATED;
1. Neisseria
2. Antimicrobial drug resistance
3. Penicillin
No comments:
Post a Comment