Alternatives to penicillin in the management of group A streptococcal pharyngitis

Over prescription of antibiotics for adult pharyngitis is prevalent in developing countries but can be reduced using McIsaac modification of Centor scores: a cross-sectional study

BACKGROUND

Although Group A beta hemolytic streptococcus (GABHS) can cause bacterial pharyngitis, the most common etiology is viral; despite this viral etiology, antibiotics are commonly prescribed for this infection in industrialized countries. We investigated the prevalence of GABHS in adult pharyngitis patients from lower socioeconomic settings in Karachi, Pakistan, how often antibiotics are prescribed for pharyngitis and if appropriate agents were used in a developing world setting. Finally, we wanted to see the usefulness of modified McIsaac scores in predicting positive cultures.

METHODS

Adult patients were recruited from three local hospital outpatient dispensaries (OPDs). All patients aged 14-65 years who were suspected of having bacterial pharyngitis had throat swabs taken. Laboratory results for GABHS pharyngitis were then compared with their prescriptions. Appropriateness (using the World Health Organization's definition) and type of antibiotic prescribed were assessed.

RESULTS

Of 137 patients, 30 patients each were studied for scores of 0, 1, 2 and 3; 17 patients were studied for score 4. Although 6 (4.4%) patients were GABHS+, for a prevalence of 43.8 per 1000 population, antibiotics were prescribed to 135 patients (98.5%). Of these, only 11.1% received appropriate antibiotics while 88.9% received inappropriate antibiotics. Penicillins were prescribed most (34.1%), especially amoxicillin/clavulanate; followed by macrolides (31.1%), especially the second-generation agents, and fluoroquinolones (14.8%). McIsaac scores were found to be 100% sensitive and 68.7% specific, giving a positive predictive value (PPV) of 12.7% and a negative predictive value (NPV) of 100%.

CONCLUSIONS

Antibiotics were prescribed irrationally to adult pharyngitis patients, as most cultures were negative for bacterial infection. McIsaac modification of Centor scores related directly to culture results. We would therefore highly recommend its use to help family physicians make treatment decisions for adult pharyngitis patients.

Management of group A streptococcus pharyngitis with a second-generation rapid strep screen: Strep A OIA

Empirical therapy of presumed group A streptococcus (GAS) pharyngitis leads to unnecessary and inappropriate use of antibiotics and pressure for emergence of resistant strains of common bacteria. Immunoassay technology has produced several rapid tests for GAS. The wide variations in diagnosis and treatment of acute pharyngitis are reviewed including the impact of rapid strep tests. Published studies comparing Strep A OIA to routine agar culture and other rapid strep screens are presented to assess the reliability and applicability of this novel assay. These data suggest that Strep A OIA may be superior to the "gold standard" throat culture and other rapid streptococcal antigen detection assays. Judicious use of Strep A OIA can result in rapid, precise diagnoses and eliminate unnecessary and inappropriate use of antibiotics. Careful antibiotic selection can reduce the pressure for emergence of resistant bacteria. This innovative, effective assay can contribute to a lessening of this serious clinical challenge.

Antibiotic use in the emergency department: I. The penicillins and cephalosporins

The penicillins and cephalosporins are beta-lactam agents that provide broad-spectrum antimicrobial coverage pertinent to many infectious diseases diagnosed in the emergency department. These groups of drugs also have in common their classification into subcategories or "generations" that delineate their usefulness in specific clinical scenarios such as infections with Gram-positive or -negative bacteria, Pseudomonas infections, or febrile neutropenic patients. Understanding these subcategories is essential to both efficacious and cost-effective use of these agents. This article reviews the pharmacology and clinical utility of the beta-lactams--including a new class of antibiotics, the carbacephams--for the emergency physician.

Group A streptococcal tonsillopharyngitis: cost-effective diagnosis and treatment

Most patients who seek medical attention for sore throat are concerned about streptococcal tonsillopharyngitis, but fewer than 10% of adults and 30% of children actually have a streptococcal infection. Group A beta-hemolytic streptococci (GAS) are most often responsible for bacterial tonsillopharyngitis, although Neisseria gonorrhea, Arcanobacterium haemolyticum (formerly Corynebacterium haemolyticum), Chlamydia pneumoniae (TWAR agent), and Mycoplasma pneumoniae have also been suggested as possible, infrequent, sporadic pathogens. Viruses or idiopathic causes account for the remainder of sore throat complaints. Reliance on clinical impression to diagnose GAS tonsillopharyngitis is problematic; an overestimation of 80% to 95% by experienced clinicians typically occurs for adult patients. Overtreatment promotes bacterial resistance, disturbs natural microbial ecology, and may produce unnecessary side effects. Existing data suggest that rapid GAS antigen testing as an aid to clinical diagnosis can be very useful. When used appropriately, it is sensitive (79% to 88%) in detecting GAS-infected patients and is specific (90% to 96%) and cost-effective. Penicillin has been the treatment of choice for GAS tonsillopharyngitis since the 1950s; 10 days of treatment are necessary for bacterial eradication. A single IM injection of benzathine penicillin is effective and obviates compliance issues. Until the early 1970s, the bacteriologic failure rate for the treatment of GAS tonsillopharyngitis ranged from 2% to 10% and was attributed to chronic GAS carriers. Since the late 1970s, the penicillin failure rate has frequently exceeded 20% in published reports. Explanations for recurrent GAS tonsillopharyngitis include poor patient compliance; reacquisition from a family member or peer, copathogenic colonization by Staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis, anaerobes that inactivate penicillin with beta-lactamase, or all these organisms; suppression of natural immune response by too-early administration of antibiotics; GAS tolerance to penicillin; antibiotic eradication of normal pharyngeal flora that normally act as natural host defenses; and establishment of a true carrier state. When therapy fails, milder symptoms may occur during the relapse. Several antimicrobials have demonstrated superior efficacy compared with penicillin in eradicating GAS and are administered less frequently to enhance patient compliance. In previously untreated GAS throat infections, cephalosporins produce a 5% to 22% higher bacteriologic cure rate; after a penicillin treatment failure, these differences are greater. Amoxicillin/clavulanate and the extended-spectrum macrolides clarithromycin and azithromycin may also produce enhanced bacteriologic eradication in comparison to penicillin.(ABSTRACT TRUNCATED AT 400 WORDS)