Strep Throat-Recurrent

Are the sore throats actually caused by strep?

Did the patient finish the prescribed antibiotic?

Is the problem antibiotic resistance or tolerance?

Is the patient experiencing repeated exposure to strep?

Is the patient not responding to antibiotics?

Has prior antibiotic therapy eliminated protective throat bacteria?

Has early, prompt antibiotic treatment suppressed natural immunity?

Is the patient a strep carrier?

What antibiotic should be selected?

Should a tonsillectomy be performed?

by Michael E. Pichichero, MD
Professor of Microbiology and Immunology, Pediatrics and Medicine
University of Rochester Medical Center
Elmwood Pediatric Group


If a child or a teenager has repeated episodes of streptococcal tonsillitis or pharyngitis ("strep throat"), several possible explanations should be considered.

Are the sore throats actually caused by strep?

Many physicians diagnose strep throat infections based on a patient's history and an examination. However, without the aid of a throat culture or a rapid strep detection test, recurrent strep throat infections are difficult to accurately diagnosis. The complaint of a sore throat is frequent in the primary care practice setting. Yet, at the peak of the strep throat infection season (late fall through early spring), strep is the cause of a sore throat in less than 30% of children and 10% of teenagers.

Therefore, strictly on a percentage basis, physicians, who diagnose strep in the majority of patients with a sore throat, over-diagnose 90% of teenagers and 70% of children. Even in a patient with typical symptoms-a fever, a red throat with yellow pus on the tonsils, swollen and tender neck lymph glands, and the absence of a runny nose and a cough-misdiagnosis is common. In one study, an overestimate of the probability of a positive strep culture was observed for 81% of the patients.

To accurately diagnose strep throat infections, physicians use throat cultures (the gold standard) or rapid strep detection tests. Rapid strep detection tests improve the accuracy of diagnosing strep throat infections. The accuracy of rapid strep detection tests varies between products, but the main variable is in the carefulness of performing the test. The critical factor is attention to detail and strictly following the manufacturers' guidelines for the test.

Table 1.	Causes of Pharyngitis
		Peak Incidence (%)
	Cause	Children	Adults
	Bacterial	30 to 40	5 to 10
	GAS	28 to 40	5 to 9
	Group C, G, or F Streptococcus	0 to 3	0 to 18
	N gonorrhoeae	0 to 0.01	0 to 0.01
	A haemolyticum	0 to 0.05	0 to 10
	M pneumoniae	0 to 3	0 to 10
	C pneumoniae	0 to 3	0 to 9
	Viral	15 to 40	30 to 60
	Idiopathic	20 to 55	30 to 65
Data compiled from Reference 1.

top

Did the patient finish the prescribed antibiotic?

Patients often do not finish the complete treatment of antibiotics. The symptoms of strep throat end quickly with antibiotics; patients feel completely better within two to three days after beginning treatment. Because of this improved well being, parent motivation to continue the medicine diminishes.

Studies from hospital-based clinics and private practices have confirmed that as many as 50% of patients have stopped taking penicillin for strep throat by the third day, 70% by the sixth day, and over 80% by the ninth day. In the same populations, over 80% of the families claimed that all of the prescribed medicine had been taken.

top

Is the problem antibiotic resistance or tolerance?

The following antibiotics-penicillin, amoxicillin, and cephalosporins (i.e., Keflex, Duricef, Ceclor, Lorabid, Ceftin, Cefzil, Vantin, Suprax, Cedax, and Omnicef)-are effective in treating strep throat infections. Infrequently, strep throat infections are resistant to Erythromycin, clarithromycin (Biaxin), and azithromycin (Zithromax).

top

Is the patient experiencing repeated exposure to strep?

Some patients are effectively treated for a strep infection with antibiotics, only to return to an environment where the infection continues to circulate. The patient then becomes re-infected and returns to the physician with a recurrent strep throat infection. Certain circumstances-crowded working conditions, schools, day care settings, and larger families-more frequently transmit strep. One small study and one case report have suggested that, in rare instances, dogs also may be carriers of strep; however, other investigations have not corroborated this possibility.

top

Is the patient not responding to antibiotics?

Even when all strep infections are laboratory confirmed with throat cultures or rapid strep detection tests, and the antibiotic is finished, failure to respond to treatment still occurs. The highest treatment failure rates observed are with penicillin; about two-thirds of presumed strep throat infections are treated with either penicillin or amoxicillin. Penicillin and amoxicillin treatment failures vary geographically, and the incidence of penicillin treatment failures for strep throat infections may be rising. Patients most likely to experience a penicillin or amoxicillin treatment failure are those who have recently received treatment with these drugs and are then retreated with the same antibiotic.

top

Has prior antibiotic therapy eliminated protective throat bacteria?

Prominent, normal bacteria of the throat include another type of streptococci (alpha hemolytic). These bacteria make natural antibiotic substances (to provide an advantage for themselves) in the throat. Penicillin or amoxicillin therapy may change the natural environment for throat bacteria by killing these alpha hemolytic streptococci; their elimination provides an opportunity for disease-causing strep to gain access to the throat cells. This is another reason for patients to avoid unnecessary antibiotic use.

top

Has early, prompt antibiotic treatment suppressed natural immunity?

With the availability of rapid strep detection tests and the publication of several convincing studies that describe faster clinical improvement from prompt treatment, many physicians have been prescribing antibiotics sooner after diagnosing strep throat infections.

Immediate penicillin treatment has been shown to be a cause of recurrent strep infections. Early antibiotic treatment suppresses the natural immune response to strep. Delaying antibiotic therapy for two days after the onset of a sore throat allows an immune response to develop, which may reduce the chance of a relapse or recurrence of strep throat infections.

Two similar studies compared immediate penicillin treatment with treatment delayed for 48 to 56 hours in 343 children with documented strep throats. Early antibiotic therapy produced a three-time increase in the frequency of recurrent infections as compared to those for whom treatment was delayed.

Table 2.	Recurrence Rates of Immediate versus Delayed Treatment of GAS Tonsillopharyngitis with Penicillin
		Treatment Group (n)(%)*
Recurrent Acute GAS Pharyngitis		Immediate Treatment(n=70)	Delayed Treatment (48 to 56 hr) (n=173)
Early recurrence		32 (19)	14 (8)	0.006
Late recurrence		22 (13)	5 (3)	0.001
Total recurrence		54 (32)	19 (11)	<.001
*Treatment groups compared by x2 of Fisher's exact test, as appropriate; data compiled from References 12 and 13.

A delay in treatment does not increase the risk of rheumatic fever since a delay of up to nine days from the onset of symptoms can be made. Nevertheless, for patients who appear severely ill or in times when highly infectious strains of strep are circulating, intentionally delayed treatment should not be considered.

top

Is the patient a strep carrier?

A positive throat culture or a rapid strep test alone cannot distinguish between the patient with strep throat and the patient with an acute viral sore throat who is a chronic strep carrier. The strep carrier has a positive throat culture, but does not show symptoms of an acute strep infection or show a rise in strep antibody levels. In clinical practice, identifying a strep carrier is problematic.

Following treatment, the patient needs to be seen again to determine whether strep is present when the patient does not have a sore throat. In addition, antibody levels need to be drawn when the patient has a sore throat and then drawn again four to six weeks later to measure strep antibodies. If antibiotic therapy has been given to treat prior symptoms, it may suppress the antibody rise, thereby negating the usefulness of this test.

Table 3.	Short-Course Treatment of Streptococcal Phayngitis
		Bacteriologic Cure
		Duration of Rx(days)	Cephalosporin or Azithromycin		Penicillin (10 days)
Cefuroxime axetil		4	82/90 (96%)		77/80 (96%)
Cefadroxil		5	87/104 (84%)		93/105 (89%)
Cefpodoxime proxetil		5	59/61 (97%)		49/52 (94%)
Cefpodoxime proxetil		5	79/82 (96%)		64/68 (94%)
Cefuroxime axetil		4	83/97 (88%)		90/103 (87%)
Cefpodoxime proxetil		5	112/121 (93%)		101/130 (78%)
Azithromycin		5	167/176 (95%)		130/187 (77%)
Azithromycin		5	139/147 (95%)		88/127 (69%)
Data compiled from Reference 15.

top

What antibiotic should be selected?

Many antibiotics---such as penicillin-can be used to treat recurrent strep throat infections.

Clindamycin or rifampin, in combination with a second antibiotic, such as penicillin, amoxicillin, or a cephalosporin, has been used to treat acute, recurrent, and carrier strep throat infections. Routine use of clindamycin is not advocated because diarrhea is a rare, but significant, side effect. Rifampin must be used with a second antibiotic because strep will rapidly become resistant to it when it is given as a single therapy. Patients should be advised that rifampin produces orange discoloration of the urine and tears (permanently staining contact lenses).

Oral cephalosporins (Keflex, Duracef, Ceclor, Lorabid, Ceftin, Cefzil, Suprax, Vantin, Omnicef, and Cedax) have gained widespread use in treating recurrent strep throat infections. When cephalosporin antibiotics are used to treat strep throat infections, a failure occurs less than 5% of the time; however, they are more expensive than penicillin or amoxicillin.

Amoxicillin/clavulanic acid (Augmentin) has been evaluated to treat strep throat with superior or equivalent results in comparison to penicillin.

Table 4.	Penicillin versus Cephalosporins in the Treatment of Streptococcal Pharyngitis
Treatment Regimen	n	Bacteriologic Failure Rate (%)	n	Clincial Failure Rate
Cephalosporins	1290	8.01	926	5.02
Penicillins	1169	16.01	865	11.02
1p = 0.0001 2p < 0.001 Data compiled from Reference 8.

top

Should a tonsillectomy be performed?

If a patient has six to seven recurrent strep throat infections over a one-to two-year time span, then a tonsillectomy should be considered after consulting with your primary care physician. Families should be advised that the procedure reduces the frequency of sore throats, and, specifically, strep throats, for two to three years after surgery.

top




About the Author

Dr. Michael E. Pichichero is currently a Professor of Microbiology and Immunology, Pediatrics and Medicine at the University of Rochester in Rochester, NY.

A graduate of the University of Rochester School of Medicine, Dr. Pichichero completed his postgraduate pediatric residency at the University of Colorado in Denver, followed by a Chief Residency and two fellowships resulting in board certification in Pediatrics, in Adult and Pediatric Allergy and Immunology and in Pediatric Infectious Disease.

Dr. Pichichero is a partner in the Elmwood Pediatric Group where he continues to practice in primary care and as a subspecialist consultant.

A recipient of numerous awards and a member of most professional societies in his fields of interest, Mike has over 300 publications in infectious diseases, immunology, and allergy.

His major practice and research interests are in vaccine development, streptococcal infections, and otitis media: in each of these areas he is a prominent international authority.