Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B, containing the RRWQWR motif, were designed, synthesized, purified, and characterized using RP-HPLC chromatography and MALDI-TOF mass spectrometry. The antibacterial activity of the designed peptides against E. coli (ATCC 11775 and 25922) and their cytotoxic effect against MDA-MB-468 and MDA-MB-231 breast cancer cell lines were evaluated. Dimeric and tetrameric peptides showed higher antibacterial activity in both bacteria strains than linear peptides. The dimeric peptide (RRWQWR)₂K-Ahx exhibited the highest antibacterial activity against the tested bacterial strains. Furthermore, the peptides with high antibacterial activity exhibited significant cytotoxic effect against the tested breast cancer cell lines. This cytotoxic effect was fast and dependent on the peptide concentration. The tetrameric molecule containing RRWQWR motif has an optimal cytotoxic effect at a concentration of 22 µM. The evaluated dimeric and tetrameric peptides could be considered as candidates for developing new therapeutic agents against breast cancer. Polyvalence of linear sequences could be considered as a novel and versatile strategy for obtaining molecules with high anticancer activity.

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B–containing non-natural amino acids and the RWQWR motif were synthesized, purified, and characterized using RP-HPLC, MALDI-TOF mass spectrometry, and circular dichroism. The antibacterial activity of peptides against Escherichia coli ATCC 11775, Stenotrophomonas maltophilia ATCC 13636, and Salmonella enteritidis ATCC 13076 was evaluated. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. The synthetic bovine lactoferricin exhibited antibacterial activity against E. coli ATCC 11775 and S. enteritidis ATCC 13076. The dimeric peptide (RRWQWR)₂K-Ahx exhibited the highest antibacterial activity against the tested bacterial strain. The monomeric, cyclic, tetrameric, and palindromic peptides containing the RWQWR motif exhibited high and specific activity against E. coli ATCC 11775. The results suggest that short peptides derived from lactoferricin B could be considered as potential candidates for the development of antibacterial agents against infections caused by E. coli.

Introduction: With the use of pneumococcal conjugate vaccines(PCV), the behavior of invasive pneumococcal disease(IPD) has changed relative to serotype distribution. The introduction of these vaccines in national immunization programs has reduced the incidence of IPD, with a marked decrease in the circulation of the serotypes included in the vaccine used in each country. However, the subsequent emergence of other serotypes not included in the vaccine, such 19A in case of PCV7 and PCV10, has been documented. Materials and methods: This was case series study (2008–2017) in pediatric patients admitted to 10 hospitals in Bogota who were diagnosed with IPD. It was conducted during the transitional period of implementing the PCV10 vaccine in Colombia in 2012. Cases of bacteremic pneumococcal pneumonia, meningitis, primary bacteremia and osteoarticular infection were included. A descriptive analysis of the demographic, clinical and laboratory variables of patients with IPD by Spn19A, its trend over time, profiles of antimicrobial susceptibility and clinical outcomes was performed. Results: There were 463 cases of IPD, 315(68%) with known serotypes. The prevalence of IPD by Spn19A was 17.7%(56 cases), tending to increase over time. During 2008–2011, the prevalence was 4.4%, and during 2014–2017, it was 32.4%, The most frequent diagnosis was pneumonia(80.4%). In nonmeningeal isolates, 39.6% were not susceptible to penicillin. An increase in the resistance was observed over time. Conclusion: Spn19A is a prevalent cause of IPD in the pediatric population of the analyzed cohort, with an increasing trend of this serotype during the surveillance period after the introduction of PCV10, being the most common serotype identified in recent years.

Determining the frequency of antimicrobial resistance amongst bacterial isolates obtained from patients in Intensive Care Units (ICU). Study data relating to 2001 to 2003 regarding microbiological isolates was obtained from a laboratory network for the ICUs of 14 third-level hospitals in Bogotá belonging to the Bogotá Bacterial Resistance Control Group (BBRCG). 27,301 isolates were obtained and their susceptibility profiles were analysed using WHONET 5.3. Staphylococcus aureus, Escherichia coli, coagulase negative Staphylococci (CNS), Pseudomonas aeruginosa y Klebsiella pneumoniae were the most commonly found microorganisms. Oxacillin-resistance rate ranged from 61% at 63% during 2001 to 2003 amongst S. aureus isolates and 78% to 83% amongst coagulase negative Staphylococci (CNS). E. coli resistance to third generation cephalosporines was found to be about 10% and over 20% to ciprofloxacin. K. pneumoniae isolates' resistance to third-generation cephalosporines was found to be more than 30% in 2001. P. aeruginosa resistance to all but a few antibiotics was found to be over 30% and multirresistance frequency was found to be 16% to 24%. The antimicrobial resistance rates found in the ICU of hospitals in Bogotá were higher than those reported in surveillance studies in the USA, Europe or other Latin-American cities.

Determining the prevalence of methicillin-resistant Staphylococcus aureus (CA-MRSA) and susceptibility to erythromycin and clindamycin (resistance profile suggestive of being CA-MRSA) in community isolates from de GREBO's database from 2001-2005. GREBO's database has been complied since 2001, using more than 22 hospitals in Bogota. S. aureus resistance profiles were determined from community isolates. Whonet 5.3 software and CLSI breakpoints (2003) were used. 2,308 S. aureus community isolates were identified. 618 (26,8 %) were methicillin-resistant Staphylococcus aureus (MRSA). 74 (3,2 %) MRSA exhibited susceptibility to all other antibiotics (erythromycin, clindamycin), suggesting that S. aureus belonged to CA-MRSA. CA-MRSA might have emerged in Bogotá thereby having a profound implication for public health due to possible dissemination in the community and because antibiotic protocols for emergency settings should be changed. The results of our study suggested that CA-MRSA could be more common in Bogotá than currently expected.