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Presented by: Dr. Michael T. Kelly
MDS Metro
A 32 year old woman was seen in a family medicine clinic with a
24h history of severe pelvic pain described by the patient as "worse
than having a baby." She also complained of right lower quadrant
pain, low back pain, and constant lower abdominal cramping. Physical
examination revealed a "toxic appearing" patient with fever
and normal blood pressure. Upon pelvic examination, a purulent cervical
discharge was noted. An intrauterine device that had been in place
for one year was removed. The purulent cervical discharge was sent
to the laboratory for gram stain and culture. The gram stain showed
abundant PMNs and gram negative bacilli. Cultures yielded heavy
growth of an oxidase positive, fermentative, gram negative bacillus.
- What type of infection does this patient have?
- Based on the characteristics described, what group of organisms
is most likely involved in this infection?
- What are the key biochemical reactions for identification
of this isolate?
The clinical diagnosis in this patient was endometritis, an infection
of the lining of the uterus. Most cases of endometritis occur after
delivery and are referred to as postpartum endometritis. The etiology
of postpartum endometritis is thought to be ascending infection
involving vulvovaginal flora. Cultures of endometrial specimens,
collected at surgery or using protected swabs that avoid the normal
vaginal flora, often yield mixed organisms, including anaerobic
bacteria, in cases of endometritis. Severe, life-threatening endometritis
(puerperal sepsis) is caused by group A streptococcal infection.
These infections have historical significance because they led to
the discoveries of Semmelweiss and others that laid the ground work
for modern infection control techniques. Today, group A strep puerperal
sepsis still occurs, and when cases are found, investigation of
health care workers who may be carriers of the organism is indicated.
Group B streptococci can also cause significant postpartum endometritis.
Chlamydia trachomatis is another cause of postpartum endometritis,
but these infections are usually less severe than those described
above. Endometrial infections that do not follow delivery or surgery
are relatively rare. Accordingly, this case represents an unusual
infection.
The characteristics of the organism isolated from this patient suggest
that it is a member of the Vibrionaceae. Positive oxidase,
negative gram reaction and fermentation of glucose are the basic
characteristics of members of this group. Members of the Vibrionaceae
may or may not exhibit curved morphology, and the curved morphology
is more often seen in initial gram stains of clinical material rather
than gram stains of cultures. Vibrios may also show pleomorphic
gram stain morphology. Critical biochemical tests for speciation
of the organism include salt requirement, decarboxylase reactions,
and carbohydrate fermentation pattern. The organism was identified
as Vibrio vulnificus. It did not grow in nutrient broth
without supplemental salt (halophilic or salt requiring). The key
biochemical characteristics of the organism were: positive lysine
and ornithine; negative arginine, and fermentation of cellobiose
and salicin but not arabinose or sucrose.
The isolation of Vibrio vulnificus from this patient was
unexpected, and additional information was solicited from the patient
in order to ascertain the possible source of the infection. The
patient indicated that she had been swimming in the Gulf of Mexico
and engaged in sexual intercourse while in the water the day before
onset of her symptoms. The presence of an intrauterine device may
also have increased the susceptibility of this patient to infection
with a marine vibrio. Vibrio vulnificus is commonly found
in the waters of the Gulf of Mexico and other warm seawater environments,
and it is a naturally occurring marine microorganism that occasionally
infects humans. Therefore, it appears that this patient acquired
her infection from exposure to the organism in seawater. Most V.
vulnificus infections present as primary septicemia that occurs
after consumption of raw shellfish, especially oysters harvested
from waters where the organism is endemic. Other manifestations
include seawater-associated wound infections. V. vulnificus
is a highly virulent organism, and infections caused by the organism
have up to a 50% mortality rate, especially in patients with
certain underlying diseases such as cirrhosis, hemochromatosis or
thalasemia. The treatment of choice is doxycycline plus ceftazidime;
this patient was treated with tetracycline, and recovered within
a few days.
- Tison DL and Kelly MT. 1983. Vibrio vulnificus endometritis.
J Clin Microbiol 20: 185-186.
- Tison DL. 1999. Vibrio. In Manual of Clinical Microbiology,
7th Edition, p. 501-502.
- Mead PB. 2000. Infections of the female pelvis. In
Principles and Practice of Infectious Diseases, 5th Edition,
p. 1236-1237.
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