Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 10) potx
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Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other
Upper Respiratory Tract Infections
(Part 10)
Diagnosis
The primary goal of diagnostic testing is to separate acute streptococcal
pharyngitis from pharyngitis of other etiologies (particularly viral) so that
antibiotics can be prescribed more efficiently for patients to whom they may be
beneficial. The most appropriate standard for the diagnosis of streptococcal
pharyngitis, however, has not been definitively established. Throat swab culture is
generally regarded as such. However, this method cannot distinguish between
infection and colonization, and it takes 24–48 h to yield results that vary according
to technique and culture conditions. Rapid antigen-detection tests offer good
specificity (>90%) but lower sensitivity when implemented in routine practice.
The sensitivity has also been shown to vary across the clinical spectrum of disease
(65–90%). Several clinical prediction systems (Table 31-3) can increase the
sensitivity of rapid antigen-detection tests to >90% in controlled settings. Since the
sensitivities achieved in routine clinical practice are often lower, several medical
and professional societies continue to recommend that all negative rapid antigen-
detection tests in children be confirmed by a throat culture to limit transmission
and complications of illness caused by group A streptococci. The Centers for
Disease Control and Prevention, the Infectious Diseases Society of America, the
American College of Physicians, and the American Academy of Family
Physicians do not recommend backup culture when adults have negative results in
a high-sensitivity, rapid antigen-detection test, however, given the lower
prevalence and smaller benefit in this age group.
Table 31-3 Guidelines for the Diagnosis and Treatment of Acute
Pharyngitis
Age
Group
Diagnostic Criteria Treatment
Recommendations
a
Adults
Clinical suspicion of
streptococcal pharyngitis
(e.g., fever,
tonsillar swelling, exudate,
enlarged/tender anterior cervical
lymph nodes, absence of cough or
Penicillin V, 500
mg PO tid, or
coryza)
b
with:
Amoxicillin, 500
mg PO bid, or
History of rheumatic fever or
Erythromycin, 250
mg PO qid, or
Documented household
exposure or
Benzathine
penicillin G, single dose of
1.2 million units IM
Positive rapid strep screen
Children
Clinical suspicion of
streptococcal pharyngitis
(e.g.,
tonsillar swelling, exudate,
enlarged/tender anterior cervical
lymph nodes, absence of coryza)
Amoxicillin, 45
mg/kg qd PO in divided
doses (bid or tid), or
with:
Penicillin VK, 50
mg/kg qd PO in divided
doses (bid), or
History of rheumatic fever or
Cephalexin, 50
mg/kg qd PO in divided
doses (qid), or
Documented household
exposure or
Benzathine
penicillin G, single dose of
25,000 units/kg IM
Positive rapid strep screen or
Positive throat culture (for
patients with negative rapid strep
screen)
a
Unless otherwise specified, the duration of therapy is generally 10 d, with
appropriate follow-up.
b
Some organizations support treating adults who have these symptoms and
signs without administering a rapid streptococcal antigen test.
Sources: Cooper et al, 2001; Schwartz et al, 1998.
Cultures and rapid diagnostic tests for other causes of acute pharyngitis,
such as influenza virus, adenovirus, HSV, EBV, CMV, and M. pneumoniae, are
available in some locations and can be used when these infections are suspected.
The diagnosis of acute EBV infection depends primarily on the detection of
antibodies to the virus with a heterophile agglutination assay (monospot slide test)
or enzyme-linked immunosorbent assay. Testing for HIV RNA or antigen (p24)
should be performed when acute primary HIV infection is suspected. If other
bacterial causes are suspected (particularly N. gonorrhoeae, C. diphtheriae, or Y.
enterocolitica), specific cultures should be requested since these organisms may
be missed on routine throat swab culture.
