Antibiotic susceptibility of Group A Streptococcus isolated from throat
swab culture of school children in Pokhara, Nepal
KR Rijal,1 N Dhakal,1 RC Shah,1 S Timilsina,1 P Mahato,1 S Thapa2 and P Ghimire2
1The School of Pharmaceutical and Biomedical Sciences, Pokhara University, 2Central Department of Microbiology, Tribhuvan University Corresponding author: Komal Raj Rijal, Lecturer, Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu,
ABSTRACTGroup A Streptococcus (GAS) or Streptococcus pyogenes is estimated to be present in 5.0-15.0% of normalindividual in the respiratory tract, vagina, skin and anus without any sign of disease. This study was carried outto find out the rate of asymptomatic throat carriage of S. pyogenes and antibiotic susceptibility of the isolatesin school children of Pokhara, Western Nepal. A total of 487 randomly selected children younger than 16 yearswere included in the study. Throat swabs collected were subjected to 5.0% Sheep blood agar supplementedwith crystal violet (CVBA).GAS was identified by â-haemolytic colonies, bacitracin sensitivity, cotrimoxazoleresistivity, catalase negativity and PYR positivity. Antibiotic susceptibility test was performed on Muller Hintonagar (MHA) containing 5% sheep blood by modified Kirby-Bauer disc diffusion method. Out of total 487throat swabs, GAS was isolated in 9.2% ( n=45). Among the isolates, 46.6% (n=21) were from male childrenwhere as 53.4% (n=24) from female children. There was no significant sex difference in colonization of GAS(p>0.05). Out of 45 isolates, 100.0% isolates were sensitive to antibiotic penicillin-G and amoxycillin where as15.6%, 6.6%, and 2.2% isolates were resistant to antibiotic erythromycin, tetracycline and azithromycinrespectively.
Keywords: GAS, CVBA, â-haemolytic, modified kirby-bauer method.
moreover, such programs are not even in the row. Little Group A Streptococcus (GAS) consists of a single information is known about the prevalence of S. species, Streptococcus pyogenes.1 It belongs to pyogenes from the throat swab of school children in Lancefield group A and is beta-hemolytic, hence called Nepal. So, this study was performed outside Kathmandu Group A beta-hemolytic Streptococci (GABHS).2 valley at Western Region, Pokhara. This study provides Streptococcal carriage bas been defined as the recovery information on prevalence, distribution and antibiotic of GAS from the nasopharynx or oropharynx in the susceptibility pattern of S. pyogenes isolates.
absence of any evidence of acute infection.3 Thepathogenesis of GAS is mediated by a variety of factors.
One of them is Streptolysin ‘O’ toxin, which damages cell membranes and accounts for the hemolysis Throat swabs of 487 school children within age limit of demonstrated on sheep blood agar.1 Disease spectrum 5-16 years were collected for the purpose of the study of Group A Streptococcus (GAS) or S. pyogenes ranges during June to October 2008. The specimens were from mild infectious as pharyngitis, tonsilitis and collected with the help of sterile throat swabs available impetigo to life threatening infections like necrotizing commercially. The swab was rubbed with rotation over fascititis and toxic-shock like syndrome. These are often one tonsilar area, then the arch of the soft palate anduvula, the other tonsilar area and finally the posterior followed by post infective sequelae of rheumatic fever, pharyngeal wall. Each sample was labeled with code rheumatic heart disease and post streptococcal acute number and various other information including age, sex, glomerulonephritis.4 GAS infection is ordinarily spread location etc were also recorded. The sample was by direct person-to-person contact, most likely via drops transported to the laboratory of the School of of saliva, nasal secretions, contaminated fingers, dust Pharmaceutical and Biomedical sciences in sterile or fomites.5 All beta-hemolytic Group A Streptococcus condition within 1-2 hours for processing as have been are sensitive to penicillin G, and most are sensitive to erythromycin. A high frequency of resistance toerythromycin in GAS has been reported, particularly in countries where antibiotics are overused.6 In Nepal The throat swab was rubbed, while being rotated over a control programs for streptococci does not exist, large well area about one third of the surface on a blood Table-1: Isolation of S. pyogenes from school children
agar plate and the well was streaked out with a loop over pharyngitis. The condition is most prevalent in the age the remainder of the plate. The plate was incubated at group of 5 to 15 years, the highest prevalence occuring 370C for 24 hours in candle jar. S. pyogenes produced in 7 years old children and rarely occuring in those under beta-hemolytic colonies i.e. the colonies were surrounded 3 years of age. Males are equally affected by GABHS by a zone of complete hemolysis with decolorization of as females. GABHS frequently colonizes the pharynx the hemoglobin. The suspected colony taken out from of asymptomatic individuals, as 15.0%-20.0% of school- primary culture on blood agar plates, were subcultured age children are asymptomatic carriers. In our study, on crystal violet blood agar plate by placing a bacitracin 9.2% of school children were colonized by GAS in their disc (0.05units) over initial streaked area and throat. Similar study done by Tavakkoli et al10 found cotrimoxazole disc in secondary streaked area and the prevalence of carriers among primary school children incubated at 370C for 24 hours supplemented with 5-10% was 4.9%. Bogovac et al11 reported 6.0% prevalence in CO . â−haemolytic colonies showing bacitracin sensitivity, all age groups and 11.7% prevalence in 6-13 years old cotrimoxozole resistivity on CVBA was further identified children from Croatia. Durmaz et al12 showed the by gram staining, catalase test and PYR test.9 prevalence of S. pyogenes nasopharyngeal carriage in14.3% healthy school children and children in an Antibiotic susceptibility test
orphanage in Turkey. The study done in Pittisburgh, All the identified GAS isolates from throat swabs were Pennsylvania reported the prevalence of carriage of subjected to in-vitro susceptibility test by modified group A streptococci in school children to be 27.0- Kirby-Bauer disc diffusion method. The antibiotics used 32.0%.13 The isolation rate of GAS was 25.9% according in the study were tetracycline (30µg), erythromycin to Ozturk et al1 in asymptomatic school children in the (15µg), cephalexin (30µg), penicillin-G (10µg), gentamycin (10µg), ciprofloxacin (5 µg), amoxicillin(30 µg) and azithromycin(15µg).
In our study, the frequency of GAS was similar in allage groups of school children, but it was slightly higher in children aged 5-8 years. The study done by Durmaz Among 487 school children, 243 (49.9%) were male et al12 in Turkey, showed that the rates of carriers for and 244 (50.1%) were female. Out of 487 throat swabs boys and girls were similar and the frequency was similar studied, S. pyogenes was isolated from 45 samples in all age groups of school children, but it was (9.2%). Among the isolates, 21 (46.6%) were from male significantly higher in children aged 4-6 years living in whereas 24 (53.4%) were from female. There was no significant sex difference in colonization of S. pyogenes Macrolides including erythromycin and clindamycin (p>0.05). Highest colonization of S. pyogenes was found have been widely used for treatment of acute pharyngitis in the age group 5-8 years (11.8%) (Table-1).
and invasive infection of GAS respectively. Kim et al6 S. pyogenes isolates indicated a relative high rate of recently reported a high frequency of resistance to resistance towards erythromycin (15.6%) followed by erythromycin in GAS, particularly in countries where tetracycline (6.6%) and azithromycin (2.2%). According antibiotics are overused. Of all throat isolates, 95.0% to our study, penicillin G and amoxicillin showed 100% were predominantly resistant to erythromycin, 70.0% sensitivity towards the isolates (Table-2).
to clindamycin, 56.0% to azithromycin and 24.0% toclarithromycin according to the study done in Sindh.14 Tamayo et al15 reported the erythromycin resistance rate Group A beta Hemolytic Streptococci (GABHS) is to be 21.7% in the study done in Spain in 2004. Ciftci among the most prevalent bacterial childhood infection et al16 reported resistance to erythromycin, and constitutes 20.0%-40.0% of all cases of exudative clarithromycin, azithromycin and clindamycin as 3.8%, Table-2: Antibiotic susceptibility pattern of S. pyogenes isolates from throat swabs
5.2%, 4.2% and 3.0% respectively. Alberti et al17 reported 6. Kim S, Lee NY. Epidemiology and Antibiotic Resistance of increased resistance of S. pyogenes to ciprofloxacin in Group A Streptococcus Isolated from Healthy School Childrenin Korea. J Antimicrob Chemother 2004; 54: 447-50.
Spain at the highest rate ever published and it is 63.3%.
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survey done in Iran by Jasir et al18 found no penicillin 9. Vandepitte J, Verhaegen J, Engbaek K et al. Basic Laboratory Procedures in Clinical Bacteriology, (2nd ed.), WHO, 2004.
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were susceptible to amoxycillin. our findings 11. Bogovac J, Bobinac E, Benic B. Asymptomatic pharyngeal demonstrate that antibiotic resistance of S. pyogenes is carriage of beta-hemolytic streptococci and streptococcalpharyngitis among patients at an urban hospital in Croatia.
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