Genomic Analysis of Kitasatospora setae to Explore Its Biosynthetic Potential Regarding Secondary Metabolites

Actinomycetes have long been recognized as important sources of clinical antibiotics. However, the exploration of rare actinomycetes, despite their potential for producing bioactive molecules, has remained relatively limited compared to the extensively studied Streptomyces genus. The extensive investigation of Streptomyces species and their natural products has led to a diminished probability of discovering novel bioactive compounds from this group. Consequently, our research focus has shifted towards less explored actinomycetes, beyond Streptomyces, with particular emphasis on Kitasatospora setae (K. setae). The genome of K. setae was annotated and analyzed through whole-genome sequencing using multiple bio-informatics tools, revealing an 8.6 Mbp genome with a 74.42% G + C content. AntiSMASH analysis identified 40 putative biosynthetic gene clusters (BGCs), approximately half of which were recessive and unknown. Additionally, metabolomic mining utilizing mass spectrometry demonstrated the potential for this rare actinomycete to generate numerous bioactive compounds such as glycosides and macrolides, with bafilomycin being the major compound produced. Collectively, genomics- and metabolomics-based techniques confirmed K. setae's potential as a bioactive secondary metabolite producer that is worthy of further exploration.

Development of New Antimicrobial Oleanonic Acid Polyamine Conjugates

A series of oleanolic acid derivatives holding oxo- or 3-N-polyamino-3-deoxy-substituents at C3 as well as carboxamide function at C17 with different long chain polyamines have been synthesized and evaluated for antimicrobial activities. Almost all series presented good to moderate activity against Gram-positive S. aureus, S. faecalis and B. cereus bacteria with minimum inhibitory concentration (MIC) values from 3.125 to 200 µg/mL. Moreover, compounds possess important antimicrobial activities against Gram-negative E. coli, P. aeruginosa, S. enterica, and EA289 bacteria with MICs ranging from 6.25 to 200 µg/mL. The testing of ability to restore antibiotic activity of doxycycline and erythromycin at a 2 µg/mL concentration in a synergistic assay showed that oleanonic acid conjugate with spermine spacered through propargylamide led to a moderate improvement in terms of antimicrobial activities of the different selected combinations against both P. aeruginosa and E. coli. The study of mechanism of action of the lead conjugate 2i presenting a N-methyl norspermidine moiety showed the effect of disruption of the outer bacterial membrane of P. aeruginosa PA01 cells. Computational ADMET profiling renders this compound as a suitable starting point for pharmacokinetic optimization. These results give confidence to the successful outcome of bioconjugation of polyamines and oleanane-type triterpenoids in the development of antimicrobial agents.

Should the Vancomycin Minimal Inhibitory Concentration be used as an Infant Critical Care Regular Criteria?

BACKGROUND

Vancomycin is the first-line antibiotic used for the treatment of staphylococcal infections. Because of its narrow therapeutic window and the pharmacokinetics variability, vancomycin trough serum concentration should be monitored. However, due to the increased cases of staphylococcus' commensal species infections and the case of vancomycin resistance, the minimal inhibitory concentration should be considered on antimicrobial therapy.

OBJECTIVE

This article aimed to show the importance of the minimal inhibitory concentration to infants on vancomycin therapy as regular criteria.

MATERIALS AND METHODS

Three infants in the use of vancomycin, hospitalized in the same maternity hospital, and that had at least one blood culture performed during the intensive-care-unit hospitalization were included in the study. Vancomycin serum concentrations were determined by particleenhanced- turbidimetric inhibition-immunoassay. The vancomycin minimal inhibitory concentration data were interpreted by following the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST). The trough serum concentration range of 10 to 20 mg.L-1 was considered therapeutic.

RESULTS

All three patients had at least one infection by S. epidermidis, being one patient exhibit vancomycin- resistant S. epidermidis infection. All patients had stoppages in the vancomycin treatment, and the minimal inhibitory concentration was performed for only one patient.

CONCLUSION

The data obtained from these patients also showed the need to perform therapeutic monitoring by using minimal inhibitory concentration values, because, although the serum concentrations were within the reference range, they are insufficient to guarantee patient therapeutic success.