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Open Access Open Badges Research article

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

Amber Hanif Palla12, Rafeeq Alam Khan3, Anwar H Gilani2 and Fawziah Marra4*

Author Affiliations

1 Department of Pharmacology, University of Karachi, Karachi, Pakistan

2 Department of Biological and Biomedical Sciences, Aga Khan University Medical College, Karachi, Pakistan

3 Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdul-Aziz University for Health Sciences, King Abdul-Aziz Medical City, Jeddah, 21423, KSA

4 Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada

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BMC Pulmonary Medicine 2012, 12:70  doi:10.1186/1471-2466-12-70

Published: 24 November 2012



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.


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.


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%.


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.

Antibiotics; Pharyngitis; McIsaac-modified Centor score; Antibiotic prescribing; Pakistan