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Introduction: Multidrug-resistant tuberculosis treatment is effective in 50% of patients due to several factors including antibiotic susceptibility of the microorganism, adverse treatment reactions, social factors, and associated comorbidities., Objectives: In this study, we describe the demographics, clinical characteristics, and factors associated with treatment outcomes in multidrug-resistant tuberculosis (MDR-TB) patients in Medellín, Colombia., Materials and Methods: We conducted a retrospective analysis using data from patients diagnosed with MDR-TB attending Hospital La María in Medellín, Colombia, for treatment between 2010 and 2015. Patients were categorized as having successful (cured) or poor (failure, lost to follow-up, and death) treatment outcomes. Associations between demographic, clinical factors, laboratory results, treatment outcomes, and follow-up information were evaluated by univariate, multivariate, and multiple correspondence analyses., Results: Of the 128 patients with MDR-TB, 77 (60%) had successful outcomes. Of those with poor outcomes, 26 were lost to follow-up, 15 died, and 10 were treatment failures. Irregular treatment, the presence of comorbidities, and positive cultures after more than two months of treatment were associated with poor outcomes compared to successful ones (p<0.05 for all). The multiple correspondence analyses grouped patients who were lost to follow-up, had HIV, and drug addiction, as well as patients with treatment failure, irregular treatment, and chronic obstructive pulmonary disease., Conclusion: The recognition of factors affecting treatment is essential and was associated with treatment outcomes in this series of patients. Early identification of these factors should increase the rates of treatment success and contribute to MDR-TB control.

Introduction: Multi-drug resistant (MDR-TB) and extensively drug-resistant (XDR-TB) tuberculoses are a global public health problem. Their timely detection might reduce the burden of the disease and the economic impact on health systems worldwide., Objective: To conduct a literature review of the diagnostic accuracy of three molecular tests to detect multi-drug resistant and extensively drug-resistant tuberculoses., Materials and Methods: A systematic literature review following Cochrane methodology was carried out to study the diagnostic accuracy of three molecular tests to detect MDR-TB and XDR-TB in previous studies among immunocompetent population. Articles indexed in Medline and Embase were reviewed starting in 2007. Diagnostic accuracy was reported by sensitivity, specificity, and positive and negative predictive values of each test., Results: In total, 8, 12 and 13 studies were included to assess the diagnostic accuracy of GeneXpert MTB/RIF®, GenoType MTBDRplus® and GenoType MTBDRsl®, respectively. The specificity of GeneXpert MTB/RIF® ranged between 91 and 100%, and its sensitivity between 33.3 and 100%. The sensitivity of GenoType® MTBDRplus® ranged between 88 and 100%. The sensitivity and specificity of GenoType MTBDRsl® to evaluate drug resistance ranged between 56 and 100% and 21 and 100%, respectively., Conclusion: The three diagnostic tests evaluated have shown an adequate diagnostic accuracy to detect MDR and XDR tuberculoses.

Introduction: A variable proportion of isolates of multidrug-resistant Mycobacterium tuberculosis also presents resistance to ethionamide. It is important to determine whether resistance to isoniazid is independent or crossed with resistance to ethionamide, given that this could lead to the re-evaluation of second-line anti-tuberculosis treatment. The GenoType MTBDR plus ® molecular test is used for the detection of MDR-MTB, as it identifies mutations associated with resistance to isoniazide and could detect cross-resistance with ethionamide., Objective: To evaluate the performance of GenoType MTBDR plus ® in comparison with sequencing in the detection of mutations in gene katG and promotor inhA in clinical isolates of multidrug-resistant M. tuberculosis ., Materials and Methods: The GenoType MTBDR plus 1.0® commercial kit and sequencing were used to evaluate mutations in gene katG and promotor inhA in 30 multidrug-resistant M. tuberculosis isolates that were resistant to ethionamide. The laboratory strain H37Rv and three pan-sensitive isolates acted as controls., Results: The kappa index for the comparison between the results of sequencing and GenoType MTBDR plus® was 1. All the isolates resistant to isoniazid and ethionamide had the mutations detected by GenoTypeMTBDR plus® in the katG gene and 40% of them in promotor inhA. Sequencing also revealed katG mutations in positions different to those detected by GenoType MTBDR plus®., Conclusion: GenoType MTBDR plus ® is able to detect resistance to isoniazid rapidly. Our results suggest that it could also be used to screen for cross-resistance with ethionamide.

Introduction: Bacterial resistance is a global phenomenon, but it presents geographic and temporal variations; this is the importance of local surveillance programs., Objective: To determine trends in antibiotic resistance in hospitals between 2007 and 2012 in Medellín and its Metropolitan Area., Materials and Methods: Percentages of antibiotic resistance between 2007 and 2012 in 22 institutions were obtained using WHONET 5.6 program. For interpretation of susceptibility results, CLSI standards of 2009 and 2012 were used. Using the Epi-Info 6.04 program a trends analysis of antibiotic resistance was done using the chi-square for linear trend with a confidence level of 95%, a value of p=0.05 was considered significant., Results: In six years of surveillance of antibiotic resistance we found a decrease of oxacillin resistance in Staphylococcus aureus (p=0.0006) and an increase of vancomycin resistance in Enterococcus faecium (p=0.0000). In Escherichia coli and Serratia marcescens an increase of resistance to ceftazidime was found, in contrast to a decrease in Klebsiella pneumoniae (p=0.0000) and Enterobacter cloacae (p=0.058). K. pneumoniae , S. marcescens and E. cloacae showed an increase of carbapenem resistance in contrast to a reduction of carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii ., Conclusions: The resistance surveillance identified important findings as the emergence of E. faecium resistant to vancomycin and carbapenem-resistant Enterobacteriaceae . It is essential to determine the antibiotic use in the region to establish their influence on the resistance profiles, as well as ensuring the quality of information and microbiological procedures in the microbiology laboratories.

Introduction: Part of the success of methicillin-resistant Staphylococcus aureus (MRSA) as a pathogen responds to the rapid spread of pandemic lineages with diverse virulence and antimicrobial susceptibility profiles. In Colombia, several healthcare-associated MRSA (HA-MRSA) clones have been found, including the pediatric clone (CC5-ST5-SCC mec IV), the Brazilian clone (CC8-ST239-SCC mec III), and the Chilean/Cordobés clone (CC5-ST5-SCC mec I). Moreover, the community-associated MRSA (CA-MRSA) clone USA300 has been reported as causing hospital-acquired infections., Objective: To describe the changes over time in the distribution of MRSA clones from a university hospital in Medellín collected at two time points a decade apart., Materials and Methods: A total of 398 MRSA strains were analyzed. Of these, 67 strains were collected in 1994, while the remaining 331 strains were collected between 2008 and 2010. Species identification and methicillin resistance were confirmed by detection of nuc and mec A genes, respectively. Molecular characterization included spa typing, SCC mec typing, PFGE and MLST., Results: Analysis of the MRSA strains collected in 1994 revealed that they belonged to a single clone, the CC5-SCC mec IV, whereas among the isolates from 2008-2010, two dominant clones were identified: CC8-SCC mec IVc, which included spa types t008 and t1610 and is closely related to the USA 300 clone, and CC5-SCC mec I ( spa type t149), related to the Chilean clone. The ST5-SCC mec IV clone from 1994 was not detected., Conclusions: This study identifies temporal dynamics in MRSA clone diversity, and highlights the importance of local surveillance and dissemination of results, especially in countries like Colombia where MRSA is prevalent and knowledge regarding its epidemiology is still insufficient.

Tuberculosis represents a public health problem worldwide, mainly in developing countries where 95% of the cases occur. New technologies that support rapid diagnosis are not available in these settings because of high cost. New, rapid, and less expensive techniques are necessary before diagnosis can be improved in these areas. The present work compared the performance of a rapid and costly culture media, thin layer agar (CD7H11), with the traditional Lowenstein-Jensen (LJ) culture method. For this comparison, 1,809 clinical specimens were processed for diagnosis of mycobacterial infections. Clinical samples were processed according to standard procedures and cultured concomitantly in LJ and CD7H11. The times required to obtain an isolate were compared for culture media. Sensitivity (S), specificity (Sp), predictive values (PPV, NPV) and agreement (kappa coefficient) were calculated for CD7H11, with LJ serving as the gold standard. CD7H11 showed S to be 73.5% (C.I.95%: 69.6-80.4), Sp to be 99.2% (C.I.95%: 98.8-99.6), PPV 90.4% (C.I.95%: 85.3-95.6) and NPV 97.6% (C.I.95%: 96.8-98.3). Agreement had a kappa coefficient of 0.52. The mean time for CD7H11 was 11 days (SD+/-4.9) compared with 26.5 (SD+/-8.6) days for LJ. Similar results were obtained in a comparison of respiratory and multibacillary clinical samples. In extrapulmonary samples and those with lowered bacillus count, CD7H11 demonstrated a lower sensitivity. The concomitant use of both culture media enhanced sensitivity of detection. CD7H11 proved a simple and rapid technique for culturing mycobacteria and can be combined with traditional methods for improving laboratory capability for diagnosis of tuberculosis.

Availability of the M. tuberculosis genome sequence and the development of sophisticated systems for genetic manipulation of bacilli offer the potential for new and effective tools to prevent and control tuberculosis. Efficient methods to inactivate mycobacterial genes have been developed. These methods have become the cornerstone for the application and development of mycobacterial functional genomics. Specific mutants are generated to establish the role of targetted genes associated with mycobacterial physiology and pathogenesis. Gene inactivation, supported directly or indirectly by the deciphering of the mycobacterial genome, has permitted the generation of large numbers of M. tuberculosis mutants. Analysis of these mutants has (in some cases) established relationships between gene products and their role in mycobacterial physiology and pathogenesis.

Streptococcus pneumoniae, a common pathogen in pediatric infections, has become resistant to penicillin and make these infections difficult to treat. Rifampin and chloramphenicol have been recommended as alternative therapies, since they are less costly and more accessible to communities with limited resources. However, their use may be restricted by the differing levels of resistance found in target populations. The objective was to determine minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) for chloramphenicol and rifampin in strains of S. pneumoniae. These strains were newly isolated from children under age 5 that had demonstrated systemic infections and meningitis. A subgroup of 107 isolates of S. pneumoniae was selected from 324 strains isolated during a period of 2 years (1994-1996). Among these isolates, 60 were penicillin-resistant and 47 were susceptible; 53 isolates were from children with meningitis. MIC and MBC for chloramphenicol and rifampicin were obtained by standard methods recommended by the National Committee for Clinical Laboratory Standards (NCCLS). S. pneumoniae ATCC strain 49619 served as the control. An isolate was considered susceptible to chloramphenicol when MIC = 4 microg/ml and resistant when MIC = 8 microg/ml. A strain was considered susceptible to rifampin when MIC = 1 microg/ml and resistant when MIC = 4 microg/ml. MBC was determined by recording the lower concentration of the antibiotic that inhibited 99.9% of the initial inoculum. Chloramphenicol resistance was found in 21% of the 107 isolates. In the group susceptible to penicillin, 11% were resistant to chloramphenicol and in the group resistant to penicillin 28% was resistant to chloramphenicol as well. MBC was found > 4 microg/ml in 28% of the isolates susceptible to penicillin and in 60% of the resistant isolates. No isolates were found resistant to rifampin. However, 2 penicillin resistant isolates showed CBM > 1 microg/ml to rifampin, and one with CIM = 1 microg/ml had a MBC to rifampicin of 16 microg/ml. Meningitis isolates showed higher CIM and CBM than the group of total isolates. These data suggest that chloramphenicol is not recommended for invasive infections caused by S. pneumoniae in Colombia. Rifampin is a more effective therapy in combination with other antibiotics for treatment of this kind of infections. Further studies are necessary to clarify the significance of low levels of MBC to rifampin found in some strains, since this may affect the efficacy of therapies that include this antibiotic.