ABSTRACT
Objective To evaluate MRSA ID chromogenic agar medium for detecting and identifying methieillin-resistant Staphylococcus aureus(MRSA).Methods 118 Staphylococcus spp. clinical isolates(including 108 Staphylococcus and 10 coagulase-negative Staphylococcus(CNS)were identified by Bacteria Auto-Identification System.MRSA ID Chromogenic Agar,oxacillin screening agar, and cefoxitin disk diffusion method were compared for detecting methicillin-resistant Staphylococcus aureus (MRSA).Meanwhile,detection of mecA gene by polymerase chain reaction(PCR)was considered as the gold standard.Escheriehia coli ATCC25922,Staphylococcus aureus ATCC25923,Pseudomonas aeruginosa ATCC27853,Enterococcus faecalis ATCC29212 were used for interference test.Results meeA gene of 108 Staphylococcus was detected by PCR and 80 strains were positive.Compared with PCR,the agreement of screening MRSA by MRSA ID chromogenic agar,oxacillin screening agar and cefoxitin disk diffusion method were 100%,97.5%,and 100%,respectively.Only one methicillin-sensitive Staphylococcus(MSSA)and one CNS were shown in wrong color and became reseda micro-colonies on the MRSA ID chromogenic agar. Standard references strains did not grow on the MRSA ID chromogenie agar.Conclusion MRSA ID chromogenic agar can be used to rapidly and initiatively detect MRSA,which is useful to take quick infection control measures.
ABSTRACT
Objective To understand the distribution of the genotypes of ?-lactamases in Chryseobacterium/Flavobacterium spp.Methods Minimum inhibitory concentrations (MICs) of 43 Chryseobacterium meningosepticum strains,22 Chryseobacterium indologenes strains and 10 Chryseobacterium gleum strains against 15 antibiotics were determined by agar dilution method.3-D test and modified 3-D test were used to identify carbapenamase.2-mercaptopropionic acid inhibitory test was used to confirm metallo-?-lactamases (MBL).Genes of ?-lactamases were amplified with 6 pairs of primers special for Chryseobacterium/Flavobacterium spp.and the amplified genes were sequenced.Results MIC_(50) and MIC_(90) of quinolones were lower comparing to other antibiotics.MICs of C.gleum against 15 antibiotics were lower than other Chryseobacterium/Flavobacterium spp.Among 43 C.meningosepticum strains,26 strains (60.5%) produce MBL,but all strains (100%) produced extended-spectrum ?-lactamases (ESBLs);12 C.indologenes strains (68.8%) produced MBL;6 (60%) C.gleum strains had MBL.Genotypes of MBL in C.meningosepticum strains were Bla-B 1,2,3,5 and 11,and Bla-GOB 2,4,6 and 8,respectively.Only one genotype,namely CME-1,was identified for ESBL in C.meningosepticum.The genotype of MBL in 3 C.indolgenes strains was IND-1,and the 6 C.gleum strains contained CGB genotype.Meanwhile,there were 8 C.indolgenes strains and 3 C.gleum strains were confirmed to produce ?-lactamase,but their genotypes were unable to be detected using the current primers,implying that there were possible novel genotypes.Conclusions Investigation of genotypes distribution of ?-lactamase in Chryseobacterium/ Flavobacterium spp.can provide theoretical evidences and rational in the selection of antibiotics,control of noscomical infection and development of novel antibiotics.