María Teresa Reguero

Computational prediction and experimental assessment of secreted/surface proteins from Mycobacterium tuberculosis H37Rv.

The mycobacterial cell envelope has been implicated in the pathogenicity of tuberculosis and therefore has been a prime target for the identification and characterization of surface proteins with potential application in drug and vaccine development. In this study, the genome of Mycobacterium tuberculosis H37Rv was screened using Machine Learning tools that included feature-based predictors, general localizers and transmembrane topology predictors to identify proteins that are potentially secreted to the surface of M. tuberculosis, or to the extracellular milieu through different secretory pathways. The subcellular localization of a set of 8 hypothetically secreted/surface candidate proteins was experimentally assessed by cellular fractionation and immunoelectron microscopy (IEM) to determine the reliability of the computational methodology proposed here, using 4 secreted/surface proteins with experimental confirmation as positive controls and 2 cytoplasmic proteins as negative controls. Subcellular fractionation and IEM studies provided evidence that the candidate proteins Rv0403c, Rv3630, Rv1022, Rv0835, Rv0361 and Rv0178 are secreted either to the mycobacterial surface or to the extracellular milieu. Surface localization was also confirmed for the positive controls, whereas negative controls were located on the cytoplasm. Based on statistical learning methods, we obtained computational subcellular localization predictions that were experimentally assessed and allowed us to construct a computational protocol with experimental support that allowed us to identify a new set of secreted/surface proteins as potential vaccine candidates.

Characterisation of carbapenem-resistant Acinetobacter calcoaceticus--A. baumannii complex isolates in a third-level hospital in Bogotá, Colombia.

John D. Clemens R. Leon Ochiai International Vaccine Institute, San 4-8 Bongcheon-7-dong, Kwanak-gu, Seoul 151-818, South Korea ∗ Corresponding author. Present address: Microbiology Division, National Institute of Cholera and Enteric Diseases, P-33 CIT Road, Scheme XM, Beliaghata, P.O. Box 177, Kolkata 700010, India. Tel.: +91 33 2370 0448/4478; fax: +91 33 2370 5066. E-mail address: shanta1232001@yahoo.co.in (S. Dutta)

Antibiotic resistance patterns of Acinetobacter calcoaceticus–A. baumannii complex species from Colombian hospitals

INTRODUCTION Only automated phenotypic methods are currently used in Colombian hospitals for identifying isolates of the Acinetobacter calcoaceticus-A. baumannii complex (ACB). The phenotypical similarities in these species mean that they cannot be differentiated by manual or automated methods, thereby leading to their identification as A. baumannii, or ACB complex in clinical settings. Our objective was to identify to the species level 60 isolates, from four hospitals, evaluate their antibiotic susceptibility, and detect resistance-related genes. METHODS 16S-23S rRNA internal transcribed spacer (ITS) region and rpoB gene partial sequences were amplified. Resistance genes for cephalosporin, carbapenem and aminoglycoside were detected by PCR. Possible mutations in the quinolone resistance-determining region (QRDR) were evaluated. The association of ISAba-1 with blaOXA and blaADC genes was determined by PCR. Amplification products of ITS region, rpoB gene and some resistance genes were sequenced and compared using the BLAST tool. RESULTS 16S-23S rRNA ITS region and partial rpoB gene sequence analysis allowed 51isolates to be identified as A. baumannii, 8 as A. nosocomialis, and 1 isolate as A. pitti. A. baumannii isolates were highly resistant to all antibiotics tested, while the others were susceptible to ciprofloxacin and ampicillin/sulbactam. Quinolone resistance, found only in A. baumannii, was associated with mutations in the QRDR region of gyrA and parC genes. CONCLUSION This is the first investigation in Colombia that has identified ACB complex species using molecular methods, and determined differences in antibiotic resistance and resistance genes among the species. It is of the highest importance to identify isolates to the species level for future resistance and epidemiology studies in our region.

Whole-Genome Sequence of a Colombian Acinetobacter baumannii Strain, a Coproducer of OXA-72 and OXA-255-Like Carbapenemases.

ABSTRACT Colombian Acinetobacter baumannii strain ST920 was isolated from the sputum of a 68-year-old male patient. This isolate possessed blaOXA-72 and blaOXA-255-like genes. The assembled genome contained 4,104,098 pb and 38.79% G+C content. This is the first case reported of the coproduction (blaOXA-72 and blaOXA-255-like) of carbapenem-hydrolyzing class D β-lactamases (CHDLs) in Acinetobacter baumannii.

Draft Genome Sequences of Multidrug-Resistant Acinetobacter sp. Strains from Colombian Hospitals

ABSTRACT The draft genome sequences of the strains Acinetobacter baumannii 107m, Acinetobacter nosocomialis 28F, and Acinetobacter pittii 42F, isolated from Colombian hospitals, are reported here. These isolates are causative of nosocomial infections and are classified as multidrug resistant, as they showed resistance to four different antibiotic groups.

[Distribution of extended spectrum β-lactamases-codifying genes in Klebsiella pneumoniae isolates from hospitals of Bogota, D.C., Colombia].

INTRODUCTION Extended spectrum β-lactamases (ESBL) are the most widely distributed enzymes in Enterobacteriaceae of Latin America and are key enzymes in resistance to antibiotics in common use. However, in Colombia, little information is available concerning the identity of genes coding for these enzymes in Klebsiella pneumoniae. OBJECTIVE The bla genes were identified in K. pneumoniae isolated from hospitals in Bogotá D.C., Colombia. Materials and methods. One hundred seventy-seven isolates of ESBL producers were collected from 10 hospitals in Bogota between 2003 and 2005. Antibiotic susceptibility was determined by disk diffusion, and the number of β-lactamases in each isolate was assessed by isoelectric focusing. blaCTX-M, blaSHV and blaTEM were identified by PCR and subsequent sequencing. RESULTS Besides, the resitenance to third generation cephalosporins, 44.7 % and 49.7 % were resistant to amikacyn and thrimetoprim-sulaphametoxazole respectively. Lower resistance rates to other antibiotics were observed as well. An average of three β-lactamases were detected by isoelectric focusing, and the genes blaCTX-M-12 (56.0%) and blaSHV-12 (33.3%) were the most prevalent. blaSHV-5 (11.8%), blaCTX-M-1-1 (4.0%), blaSHV-27 (2.8%), blaSHV-2 (2.8%), blaCTX-M-1-2 (1.7%) and blaCTX-M-1-15 (0.6%) were present in smaller percentages. In addition, three genes were identified that coded for narrow spectrum β-lactamases. CONCLUSION Eleven bla genes were identified, eight of which were ESBL-coding. The diversity of the bla genes suggested a continuing exposure of K. pneumoniae to strong antibiotic pressures in Bogota hospitals.