ABSTRACT
Polymyxins are important therapeutic options for treating infections, mainly those caused by carbapenem-resistant Klebsiella pneumoniae. Specific chemical characteristics of polymyxins make it difficult to perform antimicrobial susceptibility testing, especially within the clinical laboratory. Here we aimed to evaluate the performance of three phenotypic methods: Rapid NP Polymyxin Test, ColiSpot test and the SuperPolymyxin medium. To accomplish this, 170 non-duplicate clinical K. pneumoniae isolates were analysed (123 colistin-resistant and 47 susceptible). The sensitivity and specificity obtained for Rapid Polymyxin NP Test, Colispot and SuperPolymyxin medium were, respectively, 90% and 94%, 74% and 100%, and 82% and 85%. Very major errors occurred more frequently in low-level colistin-resistant isolates (MICs 4 and 8 µg/mL). Rapid Polymyxin NP proved to be a method capable of identifying colistin-resistant strains in acceptable categorical agreement. However, major errors and very major errors of this method were considered unacceptable for colistin-resistance screening. Although the Colispot test is promising and easy to perform and interpret, the results did not reproduce well in the isolates tested. The colistin-containing selective medium (SuperPolymyxin) showed limitations, including quantification of mucoid colonies and poor stability. Nevertheless, Colispot and SuperPolymyxin medium methods did not present acceptable sensitivity, specificity and categorical agreement. It is essential to use analytical tools that faithfully reproduce bacterial resistance in vitro, especially in last-line drugs, such as polymyxins, when misinterpretation of a test can result in therapeutic ineffectiveness.
ABSTRACT
Introduçäo: A avaliaçäo auditiva na faixa etária escolar é necessária para a identificaçäo e correçäo precoce das alteraçöes auditivas. Objetivos: Identificar e quantificar as alteraçöes audiométricas mais freqüentes em escolares. Casuística e Método: Pesquisa realizada com 121 escolares da 1ª a 8ª séries, faixa etária de 7 a 14 anos no mês de novembro de 1998 na cidade de Goiânia, por médicos otorrinolaringologistas e fonoaudiólogos através de exame clínico otorrinolaringológico, audiometria tonal e imitânciometria no Ambulatório de Otorrinolaringologia do Hospital das Clínicas da Faculdade de Medicina da Universidade Federal de Goiás. Resultados: Audiometrias realizadas em 242 orelhas foram encontradas: 76 por cento (184) orelhas com audiometria dentro dos limites da normalidade e 24 por cento (58) orelhas com audiometria alterada. As alteraçöes audiométricas mais freqüentes foram: perda auditiva condutiva em 12 por cento (26) sendo 8 por cento (16) esquerdas e 4 por cento (9) direitas, perda auditiva neurossensorial leve em 7 por cento (15) orelhas sendo 2 por cento (5) esquerdas e 5 por cento (10) direitas. Imitânciometria realizada em 242 orelhas obtendo timpanometrias alteradas sendo: curva do tipo B 3 por cento (6) e do tipo C 3 por cento (6). Conclusäo: Concluímos que as alteraçöes auditivas que ocorrem podem prejudicar a atençäo e compreensäo dos escolares, sendo importante o seu diagnóstico e tratamento precoce para obtençäo de um melhor rendimento escolar
ABSTRACT
Venoms from spiders are an important source of toxins that can help on the dissection of mechanisms involved in neurotransmission. Among them is the venom of the spider Phoneutria nigriventer that contains several toxic fractions with different targets in mammals and/or insects. We here report that one of these fractions (PhTx2) is able to evoke acetylcholine release from rat cortical synaptosomes and that this effect is dependent on extracellular calcium and is inhibited by the sodium channel blocker tetrodotoxin.
