Study of β-Haemolytic Streptococci among Pharyngitis Cases Visiting Bir Hospital
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Department of Microbiology
Abstract
Pharyngitis is commonly encountered upper respiratory tract illnesses for which
patients seek medical advice. The purpose of this study was to analyze the underlying
bacterial pathogens in pharyngitis cases. During study period February 2010 to
August, 2010, a total of 134 patients visiting E.N.T. OPD of Bir hospital complaining
sore throat were studied. Throat swabs collected were cultured to 5.0% blood agar
plate and incubated at 37
0
C of 24-48 hrs, clear transparent β-haemolytic colonies
were selected and identified. Group A streptococcus (GAS) was identified by βhaemolytic
colonies with Bacitracin and Penicillin
sensitivity, Gram
staining, catalase
negativity
and growth on crystal violet blood
agar (CVBA). In this study 23 (17.2%,
23/134)
of patients were positive for β-haemolytic
streptococci
(BHS), among
them
12 (9%) were identified as GAS. The prevalence of culture positive for BHS was
highest (56.5%, 13/23) among the age group of 21-40 years. Antibiotic susceptibility
test for isolates was done by using modified Kirby-Bauer disk diffusion method.
Pathogens other than BHS were isolated from 9 patients, of which 4 cases showed
mixed bacterial growth i.e. 14 bacterial isolates from 9 cases. Other bacterial isolates
reported in the study were Staphylococcus aureus 6 (4.5%), Klebsiella pneumoniae 5
(3.7%), Pseudomonas aeruginosa 2 (1.5%), Citrobacter freundii 1 (0.7%), and yeast
cells 1 (0.7%). It was found that infections caused by β-haemolytic streptococci is
significantly higher P=0.0084 i.e. (P<0.05) than infections caused by other bacteria.
This study demonstrated that young adults of age group 21-40 were affected by
streptococcal pharyngitis. The isolates of GAS were 100% sensitive to Amoxycillin,
Cephalexin, Cefotaxime, Ciprofloxacin and Azithromycin followed by Cotrimoxazole
(91.7%) and Erythromycin (91.7%).
Key words: β-haemolytic streptococci, BHS, Bir hospital, GAS, Pharyngitis, Sore
throat