Early treatment of streptococcal pharyngitis

FORUM Gram stain, in pharyngitis; pharyngitis, early treatment; pharyngitis, streptococcal

Early Treatment of Streptococcal Pharyngitis

The concept of treating presumed streptococcal pharyngitis prior to obtaining throat culture results remains controversial. We review the rationale for early treatment and the predictive ability of current techniques for rapidly estimating the probability of streptococcal pharyngitis. Decision analysis is combined with clinical and microscopic predictive tests to provide an approach for early treatment of presumed streptococcal pharyngitis. Our uni- fied approach supports the treatment of presumed streptococcal pharyngitis prior to obtaining culture results when specific clinical or microscopic criteria are met. [Lowe R, Hedges JR: Early treatment of streptococcal pharyngitis. Ann Emerg Med June 1984;13:440-448.]

INTRODUCTION Sore throat is the third commonest symptom that causes patients to visit

a physician's office, prompting about 15.3 million office visits in the United States in 1975.1 The annual US health care cost for pharyngitis exceeds $300 million, z Yet surprisingly little agreement exists among physicians as to proper management of the patient with a sore throat.

Causes of sore throat include viruses, Streptococcus, mononucleosis, My- coplasma, gonorrhea, and diphtheria. For a large group of patients, no cause can be established. 3-s Streptococcus is one of the most important etiologic agents because of the need for antibiotic therapy to prevent rheumatic fever.

We describe the classic clinical presentation of streptococcal pharyngitis (SP). We discuss the controversies regarding whether early antibiotic therapy for SP is important and how the diagnosis of SP should be established for both adults and children. Finally we discuss the selection of antibiotics for treatment of SP Other issues relating to SP have been discussed in recent reviews.3,4,6-8

CLINICAL PRESENTATION Classically SP presents with the sudden onset of fever, chills (without

rigors), and headache. This is followed by severe sore throat associated with a beefy red pharynx with exudate and tender anterior cervical lymph nodes. Children often have nausea, vomiting, and abdominal pain early in the illness (Figure 1). 9 Culture of the pharynx grows Group A beta-hemolytic Strep- tococcus, although other streptococci rarely can produce a similar presentation. I0 The presentation in children under three years of age is more subtle, sometimes with only a nasal discharge, af~orexia, or other nonspecific symptoms developing over several weeks. Physical examination shows rhinitis and cervical lymphadenopathy without obvious oropharyngeal involve- ment.6,1i

In nonepidemic settings the peak incidence of SP is at ages 6 to 14.s, u SP and its sequel, rheumatic fever, are more prevalent in crowded, inner-city populations 12 and in the winter.S,7

ANTIBIOTIC THERAPY The following three reasons have been given for treating SP with antibiot-

ics: to provide symptomatic relief, to prevent suppurative complications, and to prevent autoimmune complications.

Robert Lowe, MD Jerris R Hedges, MD, FACEP Cincinnati, Ohio

From the Division of Emergency Medicine, University of Cincinnati, Cincinnati, Ohio.

Received for publication July I8, 1983. Revision received November 7, I983. Accepted for publication December 5, 1983.

Address for reprints: Jerris R Hedges, MD, FACEE Division of Emergency Medicine, University of Cincinnati, 234 Goodman Street, ML 769, Cincinnati, Ohio 45267.

13:6 June 1984 Annals of Emergency Medicine 440/53

STREPTOCOCCAL PHARYNGITIS Lowe & Hedges

Fig. 1. Typical clinical pattern of streptococcal pharyngitis in school-age children (from Moffet et alg).

Symptomatic Relief Hutchison and Yassi, in their recent review~ 6 cited several

clinical trials showing that while SP is a self-limited disease, early therapy will decrease duration and severity (Ta- ble 1). The most impressive data came from Haight, I3 who studied 208 naval recruits hospitalized with scarlet fever during an epidemic. Two-thirds of those treated with penicillin or erythromycin defervesced within three days of ad- mission, while the placebo group did not achieve a similar defervescence until the sixth day. More than 90% of the antibiotic-treated patients were well after six days, while the control group required 11 days to reach the same point.

Other studies found only a 12- to 48-hour hastening of improvement with antibiotic therapy. During an epidemic of SP, sore throat, chilliness, malaise, headache, and fever resolved 12 to 24 hours sooner in patients receiving penicillin than in controls. 14 Three days after the onset of symptoms 65% of controls complained of sore throat, compared to 50% of treated patients. Therapy was more effective if begun early. When penicillin was started within 24 hours of the onset of symptoms, only 35% of patients complained of a sore throat on day 3; when antibiotic therapy was delayed until 24 to 48 hours after the onset of symptoms, 55% of patients still had a sore throat on day 3. A later article by the same group is confirmed that penicillin therapy reduces by 12 to 48 hours the duration of headache, sore throat, anorexia or nausea, tender cervical lymph nodes, pharyngeal injection, and exudate.

In an endemic setting penicillin decreased the duration of sore throat, fever, and pharyngeal injection by 19 to 24 hours36 Bennike et a117 studied a civilian population of patients ill enough to be hospitalized for acute tonsillitis. Of the patients with positive cultures, 65% of patients treated with penicillin were afebrile on the second day, compared to only 35% of controls who received no antibiotics before positive culture.

Merenstein and Rogers 18 divided outpatients with a clinical picture suggesting SP into two groups, one receiving penicillin and one receiving placebo. When culture results were returned, the therapy of all patients was changed to reflect the culture. Culture-positive patients given penicillin at the time of the initial office visit were clinically improved about 24 hours earlier than were culture-positive patients who received penicillin only after the culture report was returned. Similarly penicillin-treated patients with negative cultures reported improvement in their symptoms a mean of 24 hours before controls, a finding that was at- tributed to false-negative cultures. Some of those improving may have had a penicillin-sensitive nonstreptococcal infection. By 48 to 72 hours after onset of therapy, most patients had improved, so that no statistically significant differences remained.

It is interesting that Haight's patients 13 took more than twice as long to recover as patients in the other series. 1448 Perhaps the type 19 Streptococcus causing the epidemic that Haight studied produced a more prolonged illness that was also more responsive to antibiotic therapy. Interestingly these studies have been cited as evidence that penicillin does not alter the course of SP.3, 7

The overwhelming message, however, is that the symptoms of SP resolve 12 to 24 hours sooner when antibiotic

104 °.

~ 102 °.

(~& 100" E

98"

Vomiting

Headache

Sore Throat

Erythema

Exudate

Culture

Eurocytosis

I I

1st 2nd 3rd I

+ ÷ + + + ±

therapy is used. Early therapy seems to improve clinical response to antibiotic therapy.

Prevention of Suppurative Complications Antibiotics probably decrease the risk of suppurative

complications. From 1934 to 1936, parapharyngeal abscesses and suppurative cervical adenitis accounted for 13% of hos- pital admissions for streptococcal disease. 7 After the introduction of penicillin, these illnesses accounted for only 1.3% of the admissions. 7 Bennike et a117 found that of patients with tonsillitis, 1.1% of those treated with penicillin developed peritonsillar abscesses, cervical adenitis, or otitis media, compared to 8.6% of controls. Interestingly 27% of their control group had negative throat cultures on admis- sion that became positive on reculture later, compared to only 2% of treated patients. The higher rate of complications may partially reflect patients admitted with viral pharyngotonsillitis who acquired nosocomial streptococcal infections.

Prevention of Autoimmune Sequelae The strongest argument for treatment of SP has been the

prevention of its nonsuppurative sequel, rheumatic fever, which still affects about 100,000 patients per year in the US. 19 During an epidemic of SP in the military, the risk of acute rheumatic fever in patients with untreated SP was 2.9%, falling to 0.3% in patients treated with penicillin. In the nonepidemic setting, rheumatic fever follows SP less frequently - - in about 0.6% of cases - - but the risk seems to decrease similarly with penicillin therapy, zo

Some point out that the incidence of rheumatic fever following nonepidemic SP is low; 21 that different types of group A beta-hemolytic streptococci may carry different risks of rheumatic fever;Zl that the greatest risk of rheumatic fever occurs in ghetto populations whose members are unlikely to seek medical care for sore throats; 12 that the incidence of rheumatic fever is declining dramatically in suburbia;~2 and that some cases occur without a history of pharyngitis. 22 They argue that rheumatic fever is a public health and socioeconomic problem that cannot be resolved by treating middle-class patients with penicillin. 22

PITFALLS IN DIAGNOSIS Physicians generally accept the argument that antibiotics

should be given because of the risk of rheumatic fever in untreated SP. On the other hand, some stress the risk of overdiagnosing SP in cases of viral pharyngitis and subject-

54/441 Annals of Emergency Medicine 13:6 June 1984

TABLE 1. Studies supporting early treatment of streptococcal pharyngitis for symptomatic relief

Author Population Results

Haight 13

Brink et al TM

Denny et a115

Brumfitt et a116

Bennike et a117

Merenstein et a118

Hospitalized military recruits with scarlet fever

Military patients during a streptococcal epidemic

Military patients, majority 17-21 y

Military recruits, majority 18-21 y

Civilian patients requiring hospitalization

Private general practice - - all ages

¾ of antibiotic-treated group had fever defervescence by day 3 versus day 6 in placebo group.

Sore throat, chills, malaise, fever resolved 12-24 h sooner in patients receiving antibiotic than in controls. When therapy started within 24 h of symptom onset, only 35% complained of sore throat on day 3, versus 55% when treatment delayed 24-48 h.

Headache, sore throat, nausea, adenopathy, exudate resolved 12-48 h sooner in patients receiving antibiotic than in controls.

Sore throat, fever, and pharyngeal injection resolved 19-24 h sooner with antibiotic than with placebo.

65% of antibiotic group afebrile by second day, versus 35% of controls.

Improvement in fever and sore throat 24 h sooner when antibiotics rather than placebo given on initial presentation.

TABLE 2. Clinical findings in patients with positive and negative throat cultures (from Walsh et a128)

Total Symptoms

Rhinorrhea* Cough* Recent exposure to strep* Hearing loss

Signs Pharyngeal erythema* Pharyngeal/tonsillar exudate* Swollen tonsils* Enlarged/tender cervical nodes* Temperatures¢ (C) <37.2

37.2-38.2 >138.3"

Combinations Cough, no recent exposure, and temperature <37.8*

Recent exposure and temp />37.8" *Significant differences between the two groups (P < .01). 1-Temperatures were not available for three patients with negative cultures.

Patients With Patients With Positive Cultures Negative Cultures

(% of Total) (% of Total)

64 (100) 354 (100)

17 (26) 169 (47) 11 (17) 169 (47) 16 (25) 43 (12)

9 (14) 29 (8)

63 (98) 299 (84) 30 (47) 73 (21) 41 (64) 131 (37) 60 (93) 258 (72) 33 (52) 238 (68) 20 (31) 91 (26) 11 (17) 22 (6)

7 (11) 133 (38)

6 (9) 2 (1)

ing patients to the unnecessary risk and expense of a course of antibiotics. 23 For years journals and texts emphasized the need for precise diagnosis based on throat cultures.

Recent data have challenged this viewpoint. First, with- holding antibiotics until a culture result is available pre- vents therapy during the period when it will decrease symptoms. Second, throat cultures can be misleading. False- negative cultures have been demonstrated in studies in

which two swabs were obtained from each patient. About 10% of patients with pharyngitis who grew group A beta- hemolytic streptococci on one culture did not grow it on both.8,~4

Rising titers of antistreptolysin O antibodies (ASO) reflect recent streptococcal infection.14,21, 24-26 Of the untreated patients of Brink et al, ]4 75% had positive cultures while 82% had significant rises in ASO titer, implying at least a 7%


STREPTOCOCCAL PHARYNGITIS Lowe & H e d g e s

To understand how predictive values of clinicN criteria vary with disease prevalence, one must be familiar with the principles of probability and decision analysis. These principles have been covered in a recent text. 35 In brief:

Sensitivity = P(T+/D) = the frequency of positive test results in subjects with the disease.

Specificity = P ( T - / D - ) = the frequency of negative test results in subjects without the disease.

Prevalence = P(D) = the frequency of disease.

Predictive Value of Positive Test (PVP) = P(D/T+) = the frequency of disease in subjects with positive test results.

Predictive Value of Negative Test (PVN) = P ( D - / T - ) = the frequency of nondisease in' subjects with negative test results.

Sensitivity and specificity are independent of disease prevalence, but PVP and PVN vary with prevalence. Given knowledge of the sensitivity, specificity, and disease prevalence, positive and negative predictive values can be calculated from Bayed formula:

P(T+/D) ° P(D) P(D/T+) = P(T+/D)° P(D) + P ( T + / D - ) , P ( D - ) (Equation 1)

P(T- /D) • P(D) P(D/T- ) = P(T- /D) ° P(U) + P ( T - / D - ) ° P ( D - ) (Equation 2)

For example the data of Hedges and Wagner 37 (omitting "indeterminate" Gram stains) can be summarized as follows:

Culture

Gram Stain Positive Negative Total

Positive 6 2 8 Negative 3 41 44

Total 9 43 52

This table corresponds to:

Sensitivity = P(T+/D)

Disease

Test Present Absent Total

Positive True + False + Total " + " tests Negative False - True - Total " - " tests Total Total diseased Total healthy Totat patients

= true + total diseased

= 6/9 = 66.7%

(Continued)

Fig. 2. Calculating predictive values of clinical criteria.

false-negative culture rate. False-p0sitive cultures come from "carriers" - - patients who have streptococcal coloniza- tion of their oropharynxes but no rise in ASO titer over time. 24 While rheumatic fever has been reported without a rise in ASO titer, 25 carriers without rises in ASO or other serologic markers over time are at minimal risk for rheumatic fever.21,2s,26 If a carrier develops a viral pharyngitis, his positive throat culture may lead to an incorrect diagnosis of SP. Of patients with pharyngitis, 15% to 20% of children and 5% to 10% of adults are streptococcal carriers. 2o Serologies, the only accurate tests for tree infection, require acute and convalescent titers and are of l i t t le clinical use.

DECISION ANALYSIS A N D RHEUMATIC FEVER If the throat culture is an imperfect test for SP, the diag-

nosis on clinical grounds is also flawed. No single symptom or sign can predict SPY -g9 This led Tompkins et al 2o to calculate the cost-effectiveness of various treatments for sore

throat. The following three penicillin strategies were compared: A) treating only patients with group A beta-hemolytic streptococci proven on throat culture; B) treating all patients without obtaining cultures; and C) treating none of the patients. They concluded that in the epidemic situation, the most medically effective and least costly approach is strategy B, to treat all pat ients wi th penicillin. In the endemic situation, strategy B is also most cost-effective when oral penicillin is used in acute pharyngitis populations in which the positive throat culture yield is at least 20%. Strategy A is optimal when the yield is between 5% and 20%; below a 5% yield, strategy C is appropriate., Be- cause the risk of an allergic reaction is greater with parenteral penicillin than with oral, empirical therapy with in- t r amuscu l a r penic i l l in is no t cost -effect ive unless the positive culture yield is more than 30%, and no therapy is recommended when the yield is less than 15% (in the hypo- thetical situation in which only parenteral penicillin is available).

The analysis is open to criticism.3O, 31 I t c o m p a r e s the costs of the three strategies (accounting for the costs of such complications as penicillin reactions and rheumatic fever),


(Continued) Specificity = P ( T - / D - ) = t r u e -

total healthy = 41/43 = 95.3%

Prevalence = P(D) = total diseased total patients

= 9/52 = 1 7 . 3 %

Using Bayes' formula (Equation 1): PVP = P(D/T+)

P(T+/D) . P(D) P(T+/D) • P(D) + P ( T + / D - ) • P ( D - )

(sensitivity) (prevalence) (sensitivity) (prevalence) + (1 - specificity) (1 - prevalence)

At the prevalence found in the study, the equation becomes:

PVP = true + total " + " tests

= 6t8 = 75%

However Bayed formula can be used to establish the PVP at a prevalence of 15%.

PVP P(T + /U)° P(D) P(T+tD) , P(D) + P ( T + I D - ) ° P (D - )

(0.667) (0.15) (0.667) (0.15) + (0.047)(0.85)

= 71.5%

Similarly for PVN at the prevalence found in the study:

true - PVN -

total " - " tests = 41/44 = 93.2%

1 - P(D/T-), using Bayed formula at a prevalence of 15% (Equation 2): 1 - P ( T - / D ) . P(D)

P (T - /D) ° P(D) + P ( T - / D - ) ° P ( D - ) 1 - (1 -sensit ivity)(prevalence)

Since PVN = P ( D - / T - )

= 1 -

= 94.2%

(1 - sensitivity) (prevalence) + (specificity) (1 - prevalence) (0.333) (0.15)

(0.333) (0.15) + (0.953)(0.85)

2

depending on assumptions about the value of life and free time that are open to discussion. When strategy C is the cheapest approach, nontreatment still would cause a higher incidence of rheumatic fever than would strategy A (treating only positive cultures). Medical-legal concerns also were neglected. Failure to culture or treat pharyngitis may leave the clinician vulnerable to malpractice suits. 32 Also, the estimate of the risk of rheumatic fever made by Tompkins et a120 could be challenged. A recent study12 reports a declining incidence of rheumatic fever in suburbia, although it does not reveal whether the decrease is due to a declining incidence of SP or to decreasing rheumatogenicity of streptococcal strains. These cr i t ic isms of the analysis by Tompkins et al can be addressed by limiting the treatment options. For example one may eliminate strategy C on the basis of unaddressed medical-legal risk.

CLINICAL P R E D I C T I O N OF STREPTOCOCCAL PHARYNGITIS

While no clinical criteria can predict with complete accuracy the results of throat cultures or serologies, several authorsg,28, 33 have developed systems for estimating the

probability that a given patient has streptococcal pharyngitis. These probabilities can be incorporated into the decision analysis model in the endemic situation to help the clinician decide how to manage an individual patient.2, 34

The literature on clinical criteria for predicting SP has two primary limitations. First, most articles equate the presence of group A beta-hemolytic streptococci on throat culture with the diagnosis of SP, lint false-negative and false- positive cultures can make clinical criteria appear worse or better than they really are. Kaplan et a124 suggested that clinical criteria are less specific in predicting antibody re- sponses than in predicting positive cultures. This is hard to evaluate, because penicillin suppresses the ASO response in the presence of true infection, 13 and 80% of their 167 children with positive cultures received antibiotics. 24 Second, articles proposing clinical criteria to diagnose SP vary in the prevalence of positive cultures, a factor that influences the predictive values of the proposed criteria. We adjust the predictive values to standard prevalence figures using decision analysis in order to permit comparison of the clinical criteria. 35 The basic adjustment technique and an example are provided (Figure 2}.

13:6 June 1984 A n n a l s o f E m e r g e n c y M e d i c i n e 444/57


Adult Criteria Walsh et al2S cultured 418 adults with sore throats, and

found that 15% of cultures were positive (29% in patients under 35 and 6% in older patients). No single clinical finding could predict the culture result (Table 2). They developed an algorithm for evaluating adults with sore throats (Figure 2). Thus following the decision analysis model of Tompkins et al, 20 "high risk" patients could be treated with oral penicillin without a culture and "moderate risk" patients could be cultured. If intramuscular penicillin were used, the analysis of Tompkins et a120 would argue for culturing even the "high risk" patients of Walsh et a128 and for treating on the basis of a positive culture. Walsh et a] 2s also developed a scoring system. Points are assigned as shown (Table 3). With a culture positivity rate of 15%, scores above 30 strongly suggest SP while scores under 30 make SP unlikely.

TABLE 3. Discrimi~ant scores for adults with sore throat (from Walsh et a128)

Finding Score

Oral temperature 3 for each degree over 36,1 C

Recent exposure to streptococcal infection t 7

Recent cough - 7

Pharyngeal exudate 6

Enlarged or tender cervical nodes 11

Pediatric Criteria Moffet et al 9 obtained cultures on all nontrauma, nonder-

matology admissions to the infirmary of a boarding home for first through 12th grade students. Of 692 patients, 26.3% had positive cultures for Group A beta-hemolytic streptococci. Pharyngitis was the primary complaint of 247 patients. The investigators found the following three sigus to be especially useful in predicting positive throat cultures: 1) fever over 37.8 C at least once during the illness (when measured three times a day), 2) pharyngeal erythema, and 3) pharyngeal exudate. Of children with two or more of these findings, 72% had positive cultures. Of children with less than two findings, 90% had negative cultures. The findings were less helpful, however, in children less than 8 years of age.

Breese 33 developed a "scorecard" for predicting culture results in children (Figure 4). Using a cutoff of 30 points, he found that the scores predicted culture results quite accu- rately,

The usual rate of positive cultures in children with symptomatic pharyngitis is 35% to ~-0~o. 20,27,29,33 If we adjust the data of Moffet et al 9 and of Breese 33 for a culture positivity rate of 35%, we can estimate that 79% of children meeting two or more of the criteria of Moffet et al would have positive cultures, while 61% of children with Breese scores of 30 or higher would have positive cultures. Conversely 86% of patients meeting less than two of the criteria of Moffet et al would have negative cultures, as would 89% of those with Breese scores under 30 points. These figures are helpful in deciding whether to treat im- mediately or to treat on the basis of a positive culture. On the basis of a child having two or more of the criteria of Moffet et al or a Breese score of 30 or higher, the analysis of Tompkins et al 2o suggests that either oral or parenteral antibiotic therapy is cost-effective without a throat culture. Other clinical criteria sets have been proposed for children, but are more complex.29, 36

Microscopic Prediction of Streptococcal Pharyngitis Another approach to diagnosis of SP involves a Gram

stain of the pharyngeal swab, as described by Hedges and Wagner 37 and by Crawford et al. 38 The physician scans the slide at 100 x magnification for the areas having the most polymorphonuclear leukocytes or showing disruption of cytoplasmic integrity (cellular outlines) of leukocytes. These areas are examined at 1,000 x magnification for Gram-positive ovoid cocci occurring singly or in longitudi-

nal pairs. The organisms are rarely seen in chains and never found in clumps. Hedges and Wagner 37 listed 30% of slides as "indeterminate," and Crawford et a138 reported varying abilities of different technicians to correlate the smears with subsequent culture growth. Nonetheless, the Gram stain technique compares favorably with clinical criteria (Table 4).

The various predictive techniques proposed for adults are compared (Table 4), adjusting (Figure 2) the rate of positive throat cultures to 15% of patients with pharyngitis - - a typical rate in many series of adults.17As,2s,gL 38 If 15% of patients with sore throats had positive cultures, then 71% of the patients of Hedges and Wagner with positive Gram stains would have positive cultures, compared to 28% of patients in the high risk group of Walsh et a128 (Predictive Value of Positive Criteria); 94% of the patients of Hedges and Wagner with negative Gram stains would have negative cultures, compared to 90% of patients not meeting the high risk criteria of Walsh et al (Predictive Value of Negative Cri- teria).

EARLY TREATMENT DECISION~ We have noted that the throat culture can be falsely nega-

tive or positive. We also have stated that clinical and Gram stain criteria are imperfect predictors, and that their predictive values vary with the prevalence of positive cultures in a population. Despite these uncertainties, the techniques for rapid prediction of SP can be combined with decision analysis to guide therapy.

We believe that patients with a-clinical or Gram stain picture highly suggestive of SP should receive antibiotics without cultures being obtained. The cost-effectiveness approach of Tompkins et al 2o argues for oral penicillin if the probability of a positive throat culture is greater than 20%. Each of the clinical criteria sets described can provide probability estimates with that degree of accuracy, especially when the prevalence of positive cultures is high, as for children, for inner city populations, and during winter months.

Even if a clinician demands a higher probability of streptococcal infection before treating empirically, the pediatric clinical criteria can select children with more than a 40% to 70% probability of having positive cultures. The Gram stain technique has a predictive value sufficient to permit parenteral therapy of both adults and children when the slide is positive. When the clinical probability of streptococcal infection reaches 70%, we calculate that approximately


Enlarged or Tender I Yes Cervical Nodes? I

No

Risk Group High

Moderate Low

Number of Number of Positive

Patients Cultures (%) 127 35 (28) 153 23 (15) 138 6 (4)

_1 Pharyngeal -1 Exudate?

I No

Recent Exposure to Streptococci?

-~ No

I Recentl Cough? I

Yes I Oral Temp [ ~ ~1 ~> 38.33 C ? ~

$ 3

Sco~: Feb Mar Apr

Jan May Dec

[ ] (4)

[ ] (3)

June Oct [ ] (2) Nov

July Aug Sept

[] (I)

Nine-Item Streptococcal Score Card Age (attained age) Yes No Unknown 5 t h r u l 0 y [ ] (4) Fever 38Cormore [ ] (4) [ ] (2) [ ] (2) 4, 11, 12, 13, 14 [ ] (3) Sore throat [ ] (4) [ ] (2) [ ] (2) 3, 15 or more [ ] (2) Cough [ ] (2) [ ] (4) [ ] (4) 2 or under [ ] (1) Headache [ ] (4) [ ] (2) [ ] (2)

Abnormal pharynx [ ] (4) [ ] (1) [ ] (3) Abnormal cervical glands [ ] (4) [ ] (2) [ ] (3)

WBC 0-8.4 [ ] (1) 8.5-10.4 [ ] (2) 10,5-13.4 [ ] (3) 13.5-20.4 [ ] (5) 20.5 or more [ ] (6) Not done [ ] (3)

Doctor's Diagnosis

Yes [ ] Maybe Yes [ ] No [ ] Maybe No [ ]

4

20% of negative cultures will be falsely negative. Obviously when a culture will not affect patient management, it should not be ordered.

Similarly there may be patients whose clinical presentations and/or Gram stains convince the physician that SP is so unlikely that a positive culture would be considered a false positive (streptococcus carriers). Some clinicians would not culture or treat these patients. 2o Nonetheless even patients with unlikely clinical presentations may have serologically demonstrable streptococcal infections. 39 Therefore, in patients whom we do not treat empirically, we prefer to obtain a culture and be guided by the result. Even in patients having a low probability o5 SP, one could justify empirical antibiotic therapy if the patient will be unavail- able when the culture report returns.

THERAPY The last issue of SP is its treatment. Penicillin may be

Fig. 3. Algorithm for evaluating cases of adults with sore throats (from Walsh et a128).

Fig. 4. Nine-factor streptococcal scorecard with WBC count in thousands per cubic millimeter (from BreeseSS).

effective in preventing rheumatic fever even when therapy is delayed for nine days or more after the onset of symptoms, but the sooner t rea tment is begun the more efficacious it is.19, 26 Intramuscular benzathine penicillin G (Bici!lin-LA ®) is the most effective therapy. 19 Patients weighing more than 60 lb receive 1,200,000 units, while smaller children receive 600,000 units. In patients with little muscle mass, local reactions to the injection can be decreased by using a combination of benzathine and procaine penicillin (Bicillin C-R 900/300®). 40 Although one study in- dicates that 900,000 units of benzathine penicillin plus 300,000 units of procaine penicillin is adequate therapy in



TABLE 4. Predictive values of clinical criteria for adults wi th prevalence adjusted to 15%

Author Clinical Criteria

Walsh 28

Walsh 28

Hedges 37

Hedges 37

Crawford 38

Crawford 38

Sensitivity Specificity PVP* PVNt

"High risk" group considered positive criteria 55% 74% 28% 90%

"High" plus "moderate risk" groups considered positive criteria 91% 37% 21% 96%

Omitting "indeterminate" slides from analysis 67% 95% 71% 94%

"Positive" and "indeterminate" slides considered positive criteria 80% 68% 31% 95%

Mean value for slides read by all technicians 73% 96% 76% 95%

Slides read by worst technician 57% 94% 63% 92%

*Predictive value of positive criteria. 1-Predictive value of negative criteria.

children up to age 14, 4o the American Heart Associat ion recommends that the full dose of 1,200,000 units of benzathine penici l l in be given, regardless of the amount of procaine penici l l in present in the preparation used39

Oral penic i l l in is s l ight ly less effective than parentera l therapy but may be associated wi th fewer allergic reactions. 2o The dose is 200,000 to 250,000 units of penici l l in G three or four t imes daily for both chi ldren and aduhs. 19 Therapy mus t be cont inued for ten days, because shorter courses have s ignif icant ly greater failure rates. 41 Even in middle-class pat ients , compl iance rates are only 66% to 81%, 41 and wi th medica l ly unsophis t ica ted pat ients i t is even harder to defend oral therapy. In the penicill in-allergic patient, erythromycin 250 mg four t imes daily or 500 mg twice daily for ten days should be used for adults and 10 mg/kg/day in divided doses for children.19 Tetracycline and sulfa drugs are not uniformly effective.

S U M M A R Y Pharyngitis is an impor tant cause of short- and long-term

morbidi ty in the United States. It is impor tant to treat SP to prevent rheumat ic fever. Early t rea tment has been shown to decrease the duration and severity of symptoms and the risk of pyogenic complications. While a definite diagnosis can be made only re t rospect ively by serologic tests, c l inical and microscopic grading techniques can identify the individual wi th a high probabil i ty of streptococcal pharyngit is who is l ikely to benefit from early antibiot ic t reatment . Ant ib io t ic therapy of individuals having a low probabil i ty of 8P should await a positive throat culture result to maximize cost-effectiveness.

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2. Tompkins RK: Managing pharyngitis without the throat culture. J Faro Pract 1979;8:629-631.

3. Wannamaker LW: Perplexity and precision in the diagnosis of streptococcal pharyngitis. Am J Dis Child 1972;124:352-358.

4. Komaroff AL: A management strategy for sore throat. [AMA 1978;239:1429-1432.

5. Glezen WP, Clyde WA, Senior RJ, et ah Group A streptococcus, mycoplasmas, and viruses associated with acute pharyngitis. JAMA 1967;202:119-124.

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6. Hutchison B, Yassi AL: Resolving the sore throat dilemma. Canadian Family Physician 1981;27:471-477.

7. Peter G, Smith AL: Group A streptococcal infection of the skin and pharynx. N EngI J Med 1977i297:311-316, 365-370.

8. Wannamaker LW, Ferrieri P: Streptococcal infections - - up- dated. DM, October 1975, p 3-40.

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Early treatment of streptococcal pharyngitis