RESUMO
Direct plating of simulated stool specimens on MacConkey agar (MCA) with 10-µg ertapenem, meropenem, and imipenem disks allowed the establishment of optimal zone diameters for the screening of carbapenem-resistant Gram-negative rods (CRGNR) of ≤ 24 mm (ertapenem), ≤ 34 mm (meropenem), and ≤ 32 mm (imipenem).
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Carbapenêmicos/farmacologia , Bacilos e Cocos Aeróbios Gram-Negativos/efeitos dos fármacos , Bacilos e Cocos Aeróbios Gram-Negativos/enzimologia , Resistência beta-Lactâmica , beta-Lactamases/metabolismo , Ágar , Meios de Cultura/química , Fezes/microbiologia , Bacilos e Cocos Aeróbios Gram-Negativos/isolamento & purificação , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Testes de Sensibilidade Microbiana/métodosRESUMO
The D-zone test detects inducible clindamycin resistance in Staphylococcus spp. Two other methods not described by the Clinical and Laboratory Standards Institute (CLSI) are available to test for this resistance mechanism: an agar dilution method and new Vitek 2 cards. This study evaluated the performance of both methods in detecting inducible clindamycin resistance. Nonduplicate clinical strains of Staphylococcus spp. (111 Staphylococcus aureus and 52 coagulase-negative staphylococcus strains), intermediate or resistant to erythromycin but susceptible to clindamycin, were obtained from three hospitals in Montreal, Quebec, Canada. Molecular analysis to detect resistance genes was conducted on all strains. A Mueller-Hinton agar containing 1 mg of erythromycin and 0.5 mg of clindamycin/liter was used for the dilution method, and two inocula were tested: 10(4) and 10(5) CFU per spot. Plates were read at 24 and 48 h. The Vitek 2 AST-P580 card was used according to the manufacturer's recommendations. The results were compared to those of the D-zone test. The D-zone test was positive in 134 of 163 (82%) strains. With the 10(4) CFU inoculum, the sensitivities were 84 and 99% at 24 and 48 h, respectively. The 10(5) CFU inoculum increased the sensitivities at 24 and 48 h to 91 and 100%, respectively. The specificity was 100% for the 10(4) CFU inoculum at 24 h and 97% for the other combinations. The sensitivity and specificity for the Vitek 2 card were 93 and 100%, respectively. The performance of both the agar dilution method and the Vitek 2 card was good, but these methods were not as sensitive as the D-zone test at 24 h.
Assuntos
Antibacterianos/farmacologia , Clindamicina/farmacologia , Farmacorresistência Bacteriana , Staphylococcus aureus/efeitos dos fármacos , Animais , DNA Bacteriano/genética , Eritromicina/farmacologia , Genes Bacterianos , Hospitais , Humanos , Testes de Sensibilidade Microbiana/métodos , Quebeque , Sensibilidade e Especificidade , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificaçãoRESUMO
Disk diffusion was a reliable, easy, and inexpensive method for testing the susceptibility of Campylobacter jejuni to erythromycin (215 susceptible and 45 resistant isolates) and to ciprofloxacin (154 susceptible, two intermediate, and 124 resistant isolates) using, respectively, an erythromycin disk and ciprofloxacin and nalidixic acid disks.
