The cfr (chloramphenicol-florfenicol resistance) gene encodes a 23S rRNA methyltransferase that confers resistance to linezolid. Detection of linezolid resistance was evaluated in the first cfr-carrying human hospital isolate of linezolid and methicillin-resistant Staphylococcus aureus (designated MRSA CM-05) by dilution and diffusion methods (including Etest). The presence of cfr was investigated in isolates of staphylococci colonizing the patient's household contacts and clinical isolates recovered from patients in the same unit where MRSA CM-05 was isolated. Additionally, 68 chloramphenicol-resistant Colombian MRSA isolates recovered from hospitals between 2001 and 2004 were screened for the presence of the cfr gene. In addition to erm(B), the erm(A) gene was also detected in CM-05. The isolate belonged to sequence type 5 and carried staphylococcal chromosomal cassette mec type I. We were unable to detect the cfr gene in any of the human staphylococci screened (either clinical or colonizing isolates). Agar and broth dilution methods detected linezolid resistance in CM-05. However, the Etest and disk diffusion methods failed to detect resistance after 24 h of incubation. Oxazolidinone resistance mediated by the cfr gene is rare, and acquisition by a human isolate appears to be a recent event in Colombia. The detection of cfr-mediated linezolid resistance might be compromised by the use of the disk diffusion or Etest method.

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BackgroundMeningococcal carriage studies are important to improve our understanding of the epidemiology of meningococcal disease. The aim of this study was to determine the prevalence of meningococcal carriage and the phenotypic and genotypic characteristics of isolates collected from a sample of students in the city of Bogotá, Colombia.Materials and MethodsA total of 1459 oropharyngeal samples were collected from students aged 15–21 years attending secondary schools and universities. Swabs were plated on a Thayer Martin agar and N. meningitidis was identified by standard microbiology methods and PCR.ResultsThe overall carriage prevalence was 6.85%. Carriage was associated with cohabitation with smokers, and oral sex practices. Non-groupable and serogroup Y isolates were the most common capsule types found. Isolates presented a high genetic diversity, and circulation of the hypervirulent clonal complexes ST-23, ST-32 and ST-41/44 were detected.ConclusionThe meningococcal carriage rate was lower than those reported in Europe and Africa, but higher than in other Latin American countries. Our data also revealed antigenic and genetic diversity of the isolates and the circulation of strains belonging to clonal complexes commonly associated with meningococcal disease.

The prevalence of macrolide resistance is low in Colombian pneumococci and high in MRSA (cMLS(B)-type).

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A multiplex real-time polymerase chain reaction procedure was developed to identify the most prevalent clinical isolates of Salmonella enterica subsp. enterica. Genes from the rfb , fliC , fljB , and viaB groups that encode the O , H , and Vi antigens were used to design 15 primer pairs and TaqMan probes specific for the genes rfbJ , wzx , fliC , fljB , wcdB , the sdf-l sequence , and invA, which was used as an internal amplification control. The primers and probes were variously combined into six sets. The first round of reactions used two of these sets to detect Salmonella O:4 , O:9 , O:7 , O:8 , and O:3 ,10 serogroups. Once the serogroups were identified , the results of a second round of reactions that used primers and probes for the flagellar antigen l genes , 1 ,2; e ,h; g ,m; d; e ,n ,x; and z 10 , and the Vi gene were used to identify individual serovars. The procedure was standardized using 18 Salmonella reference strains and other enterobacteria. The procedure's reliability and sensitivity was evaluated using 267 randomly chosen serotyped Salmonella clinical isolates. The procedure had a sensitivity of 95.5% and was 100% specific. Thus , our technique is a quick , sensitive, reliable , and specific means of identifying S. enterica serovars and can be used in conjunction with traditional serotyping. Other primer and probe combinations could be used to increase the number of identifiable serovars. (J Mol Diagn 2010, 12:220 -225;