Group A beta-hemolytic streptococci can also cause invasive infections such as necrotizing fasciitis, myositis and streptococcal toxic shock syndrome. Although the skin is the most common portal of entry for these invasive infections, the pharynx has been documented as the point of entry in some cases.
Multiple factors should be considered in selecting an antibiotic to treat streptococcal pharyngitis Table 3. An algorithm for the suggested evaluation and treatment of patients with a sore throat is pro vided in Figure 1.
Adult: mg. Adult: 1,, units. Adult: not recommended. Child: 12 mg per kg for 5 days [ corrected ]. Adult: mg on day 1; mg on days 2 through 5. Adult: to mg. Adult: 1 g. Montvale, N. Cost to the patient will be greater, depending on prescription filling fee. Adapted with permission from Sloane PD, et al. Essentials of family medicine. For almost five decades, penicillin has been the drug of choice for the treatment of streptococcal pharyngitis.
This antibiotic has proven efficacy and safety, a narrow spectrum of activity and low cost. From the early s into the s, streptococcal pharyngitis was treated with a single intra muscular injection of penicillin G benzathine. Studies from the late s and the s revealed that streptococcal eradication was equal with intramuscularly and orally administered penicillins.
Thus, since the early s, oral treatment using penicillin V has been preferred. Although penicillin is effective, it does have drawbacks. About 10 percent of patients are allergic to penicillin, and compliance with a four-times-daily dosing schedule is difficult.
Fortunately, cure rates are similar for mg of penicillin V given two, three or four times daily. Bacteriologic and clinical treatment failures occur with penicillin, as with all antibiotics.
Patients with this type of treatment failure may or may not remain symptomatic. Some infected but asymptomatic patients may be carriers. Studies conducted over the past 40 years have reported penicillin V bacteriologic failure rates ranging from 10 to 30 percent and clinical failure rates ranging from 5 to 15 percent.
In children, the cure rates for amoxicillin given once daily for 10 days are similar to those for penicillin V. Amoxicillin is less expensive and has a narrower spectrum of antimicrobial activity than the presently approved once-daily antibiotics. Suspensions of this drug taste better than penicillin V suspensions, and chewable tablets are available. However, gastrointestinal side effects and skin rash may be more common with amoxicillin. Erythromycin is recommended as a first alternative in patients with penicillin allergy.
Erythromycin is absorbed better when it is given with food. Although this antibiotic is as effective as penicillin, 15 to 20 percent of patients cannot tolerate its gastrointestinal side effects. The extended spectrum of azithromycin Zithromax allows once-daily dosing and a shorter treatment course. The U. Food and Drug Administration FDA has labeled a five-day course of azithromycin as a second-line therapy for streptococcal pharyngitis. Azithromycin is associated with a low incidence of gastrointestinal side effects, and three-and four-day courses of this antibiotic have been shown to be as effective as a day course of penicillin V.
A day course of a cephalosporin has been shown to be superior to penicillin in eradicating group A beta-hemolytic streptococci. Cephalosporins have a broader spectrum of activity than penicillin V.
Unlike penicillin, cephalosporins are resistant to degradation from beta-lactamase produced by copathogens. First-generation agents such as cefa-droxil Duricef and cephalexin Keflex, Keftab are preferable to second-or third-generation agents, if used, because they offer a narrower spectrum of activity. Because of the possibility of cross-reactivity, patients with immediate hypersensitivity to penicillin should not be treated with a cephalosporin.
Cephalosporins are also expensive. Therefore, use of these agents is often reserved for patients with relapse or recurrence of streptococcal pharyngitis. The combination drug amoxicillin-clavulanate potassium Augmentin is resistant to degradation from beta-lactamase produced by copathogens that may colonize the tonsil-lopharyngeal area.
Amoxicillin-clavulanate is often used to treat recurrent streptococcal pharyngitis. Amoxicillin-clavulanate is also expensive. A recent retrospective chart review 23 found that recur rent group A beta-hemolytic streptococcal infections were more common in the s than in the s.
Within days after completing antimicrobial therapy, a small percentage of patients redevelop symptoms of acute pharyngitis, with the infection confirmed by laboratory tests. These patients have either relapse or reinfection. Theories to explain apparent treatment failures include lack of antibiotic compliance, repeat exposure, beta-lactamase-producing copathogens, eradication of protective pharyngeal microflora, antibiotic suppression of immunity and penicillin resistence.
Not all treatment failures should be regarded in the same manner. Repeated episodes in a patient should prompt a search within the patient's family for an asymptomatic carrier who, if found, can be treated. Patients who do not comply with a day course of penicillin should be offered an alternative, such as intra muscularly administered penicillin or a once-daily orally administered macrolide or cephalosporin.
Patients with clinical failure should be treated with an antimicrobial agent that is not inactivated by penicillinase-producing organisms. Amoxicillin-clavulanate potassium, cephalosporins and macrolides fall into this category. Group A beta-hemolytic streptococci persist for up to 15 days on unrinsed tooth brushes and removable orthodontic appliances.
Instructing patients to rinse toothbrushes and removable orthodontic appliances thoroughly may help to prevent recurrent infections. Transmission of group A beta-hemolytic streptococci occurs principally through contact with respiratory secretions from an infected person.
Although anecdotes are numerous and a few cases have been reported, 25 family pets are rare reservoirs of group A beta-hemolytic streptococci. During epidemics, 50 percent of the siblings and 20 percent of the parents of infected children develop streptococcal pharyngitis. Symptomatic contacts may be treated with or without cultures. Routine post-treatment throat cultures are not necessary. About 5 to 12 percent of treated patients have a positive post-treatment culture, regardless of the therapy given.
Furthermore, they are not at risk of developing rheumatic fever. Patients with streptococcal pharyngitis are considered contagious until they have been taking an antibiotic for 24 hours. Group A beta-hemolytic streptococci are the causative organisms in streptococcal necrotizing fasciitis.
Invasive streptococcus strains usually have a cutaneous portal of entry and rarely enter via the tonsillopharyngeal area. Antibiotic therapy for streptococcal pharyngitis shortens the duration of symptoms by less than one day. Salt-water gargles, lozenges, aspirin-containing gum, demulcents and other remedies all have proponents.
No evidence confirms or denies the utility of these measures. Acetaminophen or a nonsteroidal anti-inflammatory drug may be given to reduce temperature. Children and adolescents should not take aspirin. In time, rapid tests such as optical immunoassay and chemiluminescent DNA may increase the accuracy and, unfortunately, the cost of diagnosing group A beta-hemolytic streptococcal infections.
Current research on a vaccine, involving the streptococcal M pro tein, may allow prevention of the disease. A marker to identify susceptibility to rheumatic fever may make use of the vaccine in susceptible persons practical.
More research on penicillin treatment failures would be useful. If a reported increase in recurrences after antibiotic treatment 23 is con firmed elsewhere and streptococcal serotypes and drug sensitivities are, indeed, changing, penicillin will probably no longer be the drug of choice for the treatment of streptococcal pharyngitis. Already a member or subscriber? Less common and more serious side effects can also occur when taking azithromycin. Call your doctor right away if you have any of these side effects:.
If you have strep throat, your doctor will prescribe the antibiotic they think is most appropriate for you. In most cases, this would be penicillin or amoxicillin. However, some people are prescribed a Z-Pack or generic azithromycin. If you have further questions about either medication, be sure to ask your doctor.
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Strep throat is a highly contagious bacterial infection. Find out how long you should stay home if you contract it. Also get the facts on antibiotic…. Antibiotics are powerful, life-saving medications used to fight infections caused by bacteria. They decrease or kill the growth of bacteria in your….
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Get tips for soothing a sore throat, such as gargling salt water, rucking lozenges, using a humidifier, drinking tea with honey, staying hydrated, and…. Many viruses and bacteria can cause acute pharyngitis. Streptococcus pyogenes , which are also called group A Streptococcus or group A strep, cause acute pharyngitis known as strep throat.
Group A strep pharyngitis is an infection of the oropharynx caused by S. Figure 1. Streptococcus pyogenes group A Streptococcus on Gram stain. Other symptoms may include headache, abdominal pain, nausea, and vomiting — especially among children. Patients with group A strep pharyngitis typically do not typically have cough, rhinorrhea, hoarseness, oral ulcers, or conjunctivitis.
These symptoms strongly suggest a viral etiology. Patients with group A strep pharyngitis may also present with a scarlatiniform rash.
The resulting syndrome is called scarlet fever or scarlatina. Respiratory disease caused by group A strep infection in children younger than 3 years old rarely manifests as acute pharyngitis.
In contrast to typical acute group A strep pharyngitis, this presentation in young children is subacute and high fever is rare. Group A strep pharyngitis is most commonly spread through direct person-to-person transmission. Typically transmission occurs through saliva or nasal secretions from an infected person. People with group A strep pharyngitis are much more likely to transmit the bacteria to others than asymptomatic pharyngeal carriers.
Crowded conditions — such as those in schools, daycare centers, or military training facilities — facilitate transmission. Although rare, spread of group A strep infections may also occur via food. Foodborne outbreaks of pharyngitis have occurred due to improper food handling. Fomites, such as household items like plates or toys, are very unlikely to spread these bacteria.
Humans are the primary reservoir for group A strep. There is no evidence to indicate that pets can transmit the bacteria to humans. People with group A strep pharyngitis or scarlet fever should stay home from work, school, or daycare until:.
Group A strep pharyngitis can occur in people of all ages. It is most common among children 5 through 15 years of age. It is rare in children younger than 3 years of age. The most common risk factor is close contact with another person with group A strep pharyngitis. Adults at increased risk for group A strep pharyngitis include:. Crowding, such as found in schools, military barracks, and daycare centers, increases the risk of disease spread.
The differential diagnosis of acute pharyngitis includes multiple viral and bacterial pathogens. Viruses are the most common cause of pharyngitis in all age groups.
History and clinical examination can be used to diagnose viral pharyngitis when clear viral symptoms are present.
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