the lingual tonsils develop at 6.5 weeks between the second and third arches ventrally while palatine tonsils develop at 8 weeks from second pouch ( ventral and dorsal ) . tonsils are predominantly b - organs and b - lymphocytes comprise 5060% of tonsillar lymphocytes . ample evidence shows that tonsils are involved in inducing secretory immunoglobulin production [ 4 , 5 ] . both adenoids and tonsils are favourably located to mediate immunologic protection of the upper aerodigestive tract as they are exposed to air borne antigens . tonsils are particularly designed for direct transport of foreign material from the exterior to the lymphoid cells . involution of the tonsils begins after puberty , resulting in a decrease of the b cell population and a relative increase in the ratio of t to b cells . the commonest indication for tonsillectomy is recurrent tonsillitis , which results in shedding the immunologically active cells and decreasing antigen transport function with subsequent replacement by stratified squamous epithelium [ 6 , 7 ] . we investigated the common pathogens causing this condition in our hospital and report here our findings . patients presenting at our clinic with signs and symptoms of chronic tonsillitis were enrolled for the study . the study was explained to them and where children were involved , to their parents . before the operation began , the laboratory was informed and a technician stood by to collect the tonsil as soon as it was removed . sterile wide - mouthed container was provided and the excised tonsils were aseptically put into them and carried immediately to the laboratory for processing . as soon as the tonsil reaches the laboratory , it is cut into two with a sterile surgical blade ; the inner surfaces were swabbed with sterile cotton swab , and inoculated onto two blood agar plates , one macconkey agar and one chocolate agar plate . one blood agar plate was incubated anaerobically , the chocolate plate in 510% co2 while the rest of the plates were incubated aerobically . the aerobic plates and the co2 plate were examined after 24 hours ; if no growth , they were reincubated for a further 24 hours after which if still no growth , they were discarded as negative . the anaerobic cultures were examined at 72 hours and if no growth they were reincubated for a total of 7 days . there were 34 bacterial isolates from 52 patients , giving a percentage positivity of 65.38% . thirty isolates were gram - positive bacteria and only four were gram - negative , made up of two genera , klebsiella and pseudomonas . staphylococcus aureus was the predominant isolate ( 15/34 , 44.1% ) , followed by group b streptococcus ( 12/34 , 35.3% ) . others were , streptococcus pyogenes ( group a streptococcus ) , 1/34 , 2.94% ; and untypable streptococcus spp . 2/34 , 5.88% . the gram - negative bacteria consist of klebsiella pneumoniae 3/34 , 8.82% and pseudomonas aeruginosa 1/34 , 2.94% ( table 1 ) . there were no growths in 7 patients while 11 yielded growth of normal flora only . all the cases were chronic and most of them took antibiotics before presenting to us . the ratio of anaerobic to aerobic bacteria in saliva is approximately 10  :  1 because of variations in oxygen concentration throughout the oral cavity . invargsson et al . revealed that streptococcus pneumoniae was recovered in 19% of healthy children , hemophilus influenzae in 13% , group a streptococcus in 5% , and moraxella ( branhamella ) catarrhalis in 36% . the frequency of pathogens decreases with age , possibly because of increased immunity . because the oropharynx is colonized by many organisms , most infections of wadeyer 's ring are polymicrobial . in our study , but in contrast with other researchers who found beta - hemolytic streptococci to be the predominant isolate [ 14 , 15 ] . these authors also found that streptococcus pyogenes was isolated more frequently in recurrent tonsillitis while in the tonsillar hypertrophy , streptococci beta - hemolytic non a group predominated . it has been suggested that fine - needle aspiration can be used in identifying tonsil core bacteriology in clinical settings . methicillin resistant staphylococcus aureus ( mrsa ) , has been isolated from the surface and core tonsils in children . we did not encounter any mrsa in our study ; and all the staphylococcus aureus isolated were sensitive to augmentin and vancomycin . it would appear from our results , that augmentin should be our drug of choice in future treatment of tonsillitis from this centre . the findings of kuhn et al . supported the etiologic role of hemophilus influenzae and staphylococcus aureus in hypertrophic tonsils with or without inflammation [ 18 , 19 ] .
objectives . tonsillitis is a common infection in all age groups , especially under the age of five . organisms causing this condition vary from place to place . 
 our aim is to find out the main causative agents of this condition in our hospital . 
 patients and methods . 
 fifty - two consenting patients who needed tonsillectomy in khamis civil hospital , kingdom of saudi arabia , between september 2006 and april 2007 , were enrolled for the study . 
 swabs were taken from their inner surfaces and cultured for anaerobes and aerobes according to standard microbiological techniques . 
 results . 
 fifty - two patients , consisting of 30 males and 22 females were enrolled . 
 their mean age was 9.81  6.47 . 
 nearly 65% of patients had positive cultures while 35% were negative . 
 the commonest bacteria isolated were staphylococcus aureus ( 44.1% ) ; and group b streptococcus ( 35.3 % ) . 
 two gram - negative bacteria , klebsiella pneumoniae , ( 8.82% ) , and pseudomonas aeruginosa ( 2.94 % ) , were also isolated . 
 no anaerobe was isolated . 
 conclusion . 
 gram - positive cocci , consisting of staphylococcus aureus and group b streptococcus ( streptococcus agalactiae ) , are the major causes of tonsillitis requiring surgery in our hospital . 
 antibiotic treatment of this condition should be directed largely against these organisms .