RESUMEN
The frequent use of gentamycin (GM) ointment for the treatment of skin infections has led to an increase in the number of GM-resistant clinical isolates of Staphylococcus aureus. We examined the ultrastructural characteristics of 14 clinical strains of S. aureus by transmission electron microscopy. Seven of these isolates were GM-resistant, and seven isolates were GM-sensitive. We found that the cell wall of GM-resistant strains (32.24 ± 5.99 nm) was significantly thicker than that of GM-sensitive strains (19.02 ± 2.72 nm). We genetically characterized these isolates by polymerase chain reaction, targeting the genes for three aminoglycoside-modifying enzymes, aac(6')-aph(2''), aph(3')-III, and ant(4')-I. All GM-resistant strains tested carried the gene encoding aac(6')-aph(2''). However, we were unable to establish a link between a specific gene and cell wall thickening, because one GM-resistant strain was also positive for aph(3')-III. We also demonstrated that a GM-resistant mutant strain, derived in vitro from a GM-sensitive S. aureus parent strain (209P), also exhibited a thickened cell wall. These results strongly suggest that a thickened cell wall is a common ultrastructural characteristic of GM-resistant S. aureus clinical strains.
Asunto(s)
Antibacterianos/uso terapéutico , Pared Celular/ultraestructura , Gentamicinas/uso terapéutico , Staphylococcus aureus/ultraestructura , Pared Celular/efectos de los fármacos , Humanos , Resistencia a la Meticilina/efectos de los fármacos , Resistencia a la Meticilina/genética , Pruebas de Sensibilidad Microbiana , Microscopía Electrónica de Transmisión , Infecciones Cutáneas Estafilocócicas/genética , Infecciones Cutáneas Estafilocócicas/microbiología , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidadRESUMEN
Real time monitoring of airborne pollen has gradually increased because monitoring is laborsaving and provides better real-time information. A problem arose, however, due to differences between the KH3000 (Yamato Co. Ltd) monitor and the conventional Durham sampler pointed out in results of airborne pollen monitoring in Wakayama in 2004. We compared the two monitors for airborne pollen in Wakayama in 2004, which less dispersed than usual. The peak monitored by the KH-3000 monitor was not consistent with the prime period of Japanese cedar and cypress pollen dispersion, especially in February and April, although they correlated highly in March. The inconsistency in February is thought to be caused by snow, and that in April by falsely monitoring beech-tree airborne pollen-which is similar in size-in addition to Japanese cedar and cypress pollen. This report points out the need to take these conditions (snow and other plants pollen) into account when a real time monitor is used for collecting pollen information.