CASE FILES: BIOCHEMISTRY
A N SW E R S TO C A SE 10: PE L V IC IN FL A M M A T O R Y
D ISE A SE
A 20-year-old female with history of new sexual partner, fever,
abdominal and pelvic pain, foul-smelling discharge through cervical os, and
severe cervical motion tenderness.
Most likely diagnosis: Pelvic inflammatory disease
Biochemical mechanism of action of quinolone: Inhibits DNA gyrase
Function of topoisomerases: Enzymes that assist in formation of
superhelices and regulate the breaking and rejoining of DNA chains
C L IN IC A L C O R R E L A T IO N
Pelvic inflammatory disease (PID) is usually an acute infection affecting the
fallopian tubes and possibly the uterus and ovaries. It is generally sexually
transmitted, caused by organisms such as
(gonorrhea). The diagnosis is made clinically based on the typical history and
physical examination. A purulent cervical discharge is highly suggestive.
Nearly all patients have cervical motion tenderness, that is, pain with motion
and palpation of the cervix. The treatment is with antibiotics. Quinolone antibi-
otics have been popular in the past; however, increasing bacterial resistance,
particularly in Southeast Asia and California, has rendered these agents less
desirable. Complications of PID include infertility or ectopic pregnancy (preg-
nancy in the tube) as consequence of tubal damage.
A PPR O A C H TO D N A T O P O L O G Y
Know about DNA superhelices.
Understand the role of topoisomerases and DNA gyrase.
Understand the importance of histones and nonhistone proteins.
Be familiar with nucleosomes and polynucleosomes.
Know about the chromosomal structure.
DNA gyrase: A type II topoisomerase enzyme present in bacteria that
introduces negative supercoils into the DNA double helix in advance of
the replication fork.
Histones: Proteins containing a large number of positively charged amino
acids (lysine, arginine) that associate with DNA to form nucleosomes.