RESUMEN
The presence of Beta-lactamase gene in microorganism is believed to be responsible for resistance of subsequent infections to routine and penicillin derivates antibiotics. As such bacteria resistance has been a continuing and evolving problem in the management of the case efforts are centered on the distribution of such gene to provoke clinicians to use alternative antimicrobial agents. This investigation was aimed at the presence of the beta-lactamase gene in microorganisms responsible for peri-apical infections of primary teeth. Samples were taken from dental abscess of infected teeth from a group a 40 children attending the pediatric dental clinic. They aged 4-10 with at least 1 infected primary tooth with no systemic background. Attempts were made to make sure none of the selected cases had received any antibiotics during the last two weeks prior to sampling. The rapid and fine rapid polymerase chain reaction technique [PCR] was used to identify the gene transcript including any beta-lactamase gene presence. Data were analyzed by chi-square test. Assessing the collected data and a further analysis revealed the presence rate of beta-lactamase at 63.2% of the cases. As the presence of the beta-lactamase gene was approved in more than 60% of the cases a definite need for a more appropriate and precise antibiotic therapy of infected primary teeth is recommended