Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1360 page)

   
Female:

   Urethral swabs or swabs from the cervical os are recommended. The cervix is visualized using a speculum lubricated only with water. Prior to collection of cervical specimens, mucus from the exocervix should be removed by use of a cleaning swab.

   Vaginal specimens are not recommended for routine genital cultures. Vaginal specimens may be useful for diagnosis of vaginal candidiasis,
Trichomonas vaginalis
infection, or
S
.
aureus
superinfection.

   Other specimens usually require more invasive sampling techniques, such as endometrial curettage, Bartholin gland aspiration, and culdocentesis.

   Interpretation

   
Expected results:
Cultures should yield only endogenous flora for the specimen submitted.

   
Positive:
The interpretation of positive cultures may depend on the organism isolated and the quantity.
N
.
gonorrhoeae
is never normal flora and indicates gonorrhea.

   
Negative:
A single negative culture does not rule out infection with
N
.
gonorrhoeae
or other genital pathogen. Sampling several sites, like the cervix and urethra, and serial sampling may improve detection.

   Limitations

   The symptoms related to genital infections may overlap with those of UTI, so urine cultures are recommended for most patients for whom genital cultures are submitted. Routine genital cultures are most often submitted for diagnosis of an STD caused by
N
.
gonorrhoeae
. A number of STDs will not be detected by routine bacterial genital culture, including
C
.
trachomatis
,
Treponema pallidum
,
Haemophilus ducreyi
,
Ureaplasma urealyticum
,
T
.
vaginalis
, HSV, and HPV. Special cultures or procedures are needed for detection of infections with these pathogens. See
Group B Streptococcus Rectovaginal Culture Screen
for detection of group B beta-hemolytic
Streptococcus
carriage during pregnancy.

   Additional information:

   Special cultures are required to detect
N
.
gonorrhoeae
infections of non-genital sites, such as the rectum or throat.