Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (472 page)

   Most women with
N. gonorrhoeae
infection present with cervical and urethral infection. Symptoms include vaginal and urethral discharge, pelvic pain, and abnormal vaginal bleeding. Adjacent structures, like Bartholin glands, may become infected by local spread. Ascending infection, resulting in pelvic inflammatory disease (PID) (e.g., salpingitis, endometritis, tuboovarian abscess, perihepatitis), occurs in 10–20% of patients. Anorectal infection in women is most commonly acquired by autoinfection by infected vaginal secretions. PID increases the risk of sterility and tubal pregnancy.
N. gonorrhoeae
infection during pregnancy may result in premature delivery or spontaneous abortion, chorioamnionitis, and transmission of infection (conjunctival or pharyngeal) to the neonate.

   Laboratory Findings

Direct detection
: Gonorrhea may be diagnosed accurately by Gram stain of urethral secretions from symptomatic males. The detection of typical gram-negative diplococci within PMNs is diagnostic (S/S of approximately 95%). Gram stain examination of endocervical secretions may support a diagnosis of gonorrheal cervical or anorectal infection if many intracellular gram-negative diplococci are seen (sensitivity approximately 50%), but smears must be interpreted with caution because of the presence of nonpathogenic gram-negative organisms in the endogenous flora of these sites.

Culture
: The gold standard for diagnosis of nongenital
N. gonorrhoeae
infections. Swabs of secretions of anal crypts should be submitted for diagnosis of anorectal gonorrhea; rectal swabs (heavily contaminated with feces) should not be submitted. Cultures are required for other types of specimens and for medicolegal specimens (e.g., child abuse, rape).

Molecular diagnosis
: Considered the gold standard for diagnosis of
N. gonorrhoeae
genital infection. Several advantages of nucleic acid testing include the ability to detect nonviable organisms and increased sensitivity, allowing diagnostic testing on urine specimens. Tests with S/S >98% are available, depending on the assay and specimen type.

NEISSERIA MENINGITIDIS
INFECTION

   Definition

Neisseria meningitidis
is a moderately fastidious gram-negative diplococcus with characteristic “coffee bean” morphology.
Neisseria meningitidis
may be isolated as components of the endogenous respiratory flora of healthy individuals. In meningococcal disease, infection is usually transmitted by the respiratory route. In susceptible patients, bacteremia may occur by passage of organisms across the epithelial barrier. Infection in multiple organ systems is common in meningococcal disease.

   Who Should Be Suspected?

Common infectious syndromes include the following:

   Meningococcemia: Meningococcemia may result in sustained bacteremia and seeding of various organ systems. Sustained bacteremia is typically associated with fever, malaise, and leukocytosis. Fulminant disease is usually associated by seeding of the CNS and other organs, DIC, adrenal insufficiency, and multiorgan failure. Meningitis should be actively ruled out by clinical and laboratory evaluation in patients in whom meningococcemia is documented.

   CNS infection (meningitis and meningoencephalitis):

   More than 90% of adults with clinically significant meningococcal infections have meningitis. Patients with CNS disease usually present with typical signs and symptoms of meningitis.

   The clinical presentation may be dominated by symptoms of fulminant disease and multiorgan failure. Overwhelming disease may be associated with shock, petechial rash, purpura fulminans, gangrenous necrosis of the distal extremities, or the Waterhouse-Friderichsen syndrome (3–4% of patients).

   Laboratory Findings

Direct detection
: CSF Gram stain is diagnostic in 50–70% of patients with meningitis; pyogenic meningitis in which bacteria cannot be found in smear is more likely to be caused by meningococcus than to other bacteria.

Core laboratory
: Increased WBC count (12,000–40,000/μL). Urine may show albumin, RBCs; occasional glycosuria. Laboratory findings of predisposing conditions such as asplenia (e.g., sickle cell anemia) or immunodeficiency (e.g., complement, immunoglobulin). Laboratory findings due to complications (e.g., DIC) and sequelae (e.g., subdural effusion) may be seen.

CSF findings
: Markedly increased WBC count (2,500–10,000/μL), almost all PMNs; increased protein (50–1,500 mg/dL); decreased glucose (0–45 mg/dL).

PASTEURELLA MULTOCIDA
INFECTION

   Definition