Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 10) potx

Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections Part 10 Diagnosis The primary goal of diagnostic testing is to separate acute streptococcal pharyngitis fr

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

Recommendationsa

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

mg PO bid, or

History of rheumatic fever or Erythromycin, 250

mg PO qid, or

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

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

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