Outcome of treatment of MDR-TB or drug-resistant patients treated with bedaquiline and delamanid: Results from a large global cohort

The World Health Organization (WHO) recommends countries introduce new anti-TB drugs in the treatment of multidrug-resistant tuberculosis. The aim of the study is to prospectively evaluate the effectiveness of bedaquiline (and/or delamanid)- containing regimens in a large cohort of consecutive TB patients treated globally. This observational, prospective study is based on data collected and provided by Global Tuberculosis Network (GTN) centres and analysed twice a year. All consecutive patients (including children/adolescents) treated with bedaquiline and/or delamanid were enrolled, and managed according to WHO and national guidelines. Overall, 52 centres from 29 countries/regions in all continents reported 883 patients as of January 31st 2021, 24/29 countries/regions providing data on 100% of their consecutive patients (10-80% in the remaining 5 countries). The drug-resistance pattern of the patients was severe (>30% with extensively drug-resistant -TB; median number of resistant drugs 5 (3-7) in the overall cohort and 6 (4-8) among patients with a final outcome). For the patients with a final outcome (477/883, 54.0%) the median (IQR) number of months of anti-TB treatment was 18 (13-23) (in days 553 (385-678)). The proportion of patients achieving sputum smear and culture conversion ranged from 93.4% and 92.8% respectively (whole cohort) to 89.3% and 88.8% respectively (patients with a final outcome), a median (IQR) time to sputum smear and culture conversion of 58 (30-90) days for the whole cohort and 60 (30-100) for patients with a final outcome and, respectively, of 55 (30-90) and 60 (30-90) days for culture conversion. Of 383 patients treated with bedaquiline but not delamanid, 284 (74.2%) achieved treatment success, while 25 (6.5%) died, 11 (2.9%) failed and 63 (16.5%) were lost to follow-up.

Mycobacterium tuberculosis multi-drug-resistant strain M induces IL-17+ IFNγ- CD4+ T cell expansion through an IL-23 and TGF-β-dependent mechanism in patients with MDR-TB tuberculosis

We have reported previously that T cells from patients with multi-drug-resistant tuberculosis (MDR-TB) express high levels of interleukin (IL)-17 in response to the MDR strain M (Haarlem family) of Mycobacterium tuberculosis (M. tuberculosis). Herein, we explore the pathways involved in the induction of Th17 cells in MDR-TB patients and healthy tuberculin reactors [purified protein derivative healthy donors (PPD⁺ HD)] by the M strain and the laboratory strain H37Rv. Our results show that IL-1β and IL-6 are crucial for the H37Rv and M-induced expansion of IL-17⁺ interferon (IFN)-γ^- and IL-17⁺ IFN-γ⁺ in CD4⁺ T cells from MDR-TB and PPD⁺ HD. IL-23 plays an ambiguous role in T helper type 1 (Th1) and Th17 profiles: alone, IL-23 is responsible for M. tuberculosis-induced IL-17 and IFN-γ expression in CD4⁺ T cells from PPD⁺ HD whereas, together with transforming growth factor (TGF-β), it promotes IL-17⁺ IFN-γ^- expansion in MDR-TB. In fact, spontaneous and M. tuberculosis-induced TGF-β secretion is increased in cells from MDR-TB, the M strain being the highest inducer. Interestingly, Toll-like receptor (TLR)-2 signalling mediates the expansion of IL-17⁺ IFN-γ^- cells and the enhancement of latency-associated protein (LAP) expression in CD14⁺ and CD4⁺ T cells from MDR-TB, which suggests that the M strain promotes IL-17⁺ IFN-γ^- T cells through a strong TLR-2-dependent TGF-β production by antigen-presenting cells and CD4⁺ T cells. Finally, CD4⁺ T cells from MDR-TB patients infected with MDR Haarlem strains show higher IL-17⁺ IFN-γ^- and lower IL-17⁺ IFN-γ⁺ levels than LAM-infected patients. The present findings deepen our understanding of the role of IL-17 in MDR-TB and highlight the influence of the genetic background of the infecting M. tuberculosis strain on the ex-vivo Th17 response.

Conjugal Transfer of Broad-Host-Range Plasmid pAMbeta1 into Enteric Species of Lactic Acid Bacteria

The broad-host-range plasmid pAMbeta1, which codes for erythromycin and lincomycin resistance, was transferred by conjugation into Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus salivarius. A novel 17-megadalton plasmid molecule was detected in the transconjugants, confirming the introduction of pAMbeta1 into each species.

Extraction and partial characterization of proteolytic activities from the cell surface of Lactobacillus helveticus Zuc2

Proteolytic activities were extracted from a dairy Lactobacillus helveticus strain and partially characterized. A first cell envelope proteinase (CEP) was extracted using a high ionic strength buffer, both in the presence and in the absence of Ca2+. Moreover, cell treatment by 5 M LiCl allowed for the selective removal of the S-layer protein and CEP, suggesting an enzyme ionic linkage to the cell envelope similar to that observed for the Slayer structure. The enzyme specificity against alpha(s1)-CN (f1-23) showed unusual activity on the Lys3-His4 bond compared with other proteinases of the same species. A second proteinase appeared to be linked to the cell membrane because it was extractable only after membrane disgregation by detergents. Its specificity against CN fractions and alpha(s1)-CN (f1-23) was different from that of the first CEP; moreover, the measured activity was lower than that of CEP.

Partial characterization of a bacteriocin produced by Lactobacillus helveticus

AIMS

To investigate the antimicrobial activity of a strain of Lactobacillus helveticus.

METHODS AND RESULTS

The culture supernatant fluid Lact. helveticus G51 showed antimicrobial activity against thermophilic strains of Lactobacillus. Purification of the active compound was achieved after gel filtration and ion exchange chromatography. As revealed by SDS-PAGE, active fractions were relatively homogeneous, showing a protein with a molecular mass of 12.5 kDa. The antimicrobial compound was heat labile, inactivated by proteolytic enzymes and had a bactericidal mode of action.

CONCLUSION

The antimicrobial activity expressed by Lact. helveticus G51 was correlated with the production of a bacteriocin with properties that were different to other helveticins.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study has provided further data on Lact. helveticus bacteriocins. The strong activity of the bacteriocin towards various thermophilic lactobacilli warrants further investigation for its potential to obtain attenuated cultures for the enhancement of the cheese-ripening process.

Partial characterization and plasmid linkage of a non-proteinaceous antimicrobial compound in a Lactobacillus casei strain of vegetable origin

Lactobacillus casei IMPC LC34 of vegetable origin produces a non-proteinaceous inhibitory compound with a broad spectrum of activity towards Gram-positive and Gram-negative bacteria, including pathogens. The active substance, mainly produced in the stationary phase of growth, is insensitive to proteolytic enzymes, lipase and catalase, and is stable at 121 degrees C for 30 min. The inhibitory activity was detected either at 8 degrees C or at 37 degrees C. The active compound does not contain glucidic groups, is inactivated by Na-metaperiodate, and its molecular mass is between 2000 and 5000 Da. Plasmid curing experiments showed that both antimicrobial compound immunity and production determinants were encoded by an 8.8 kbp plasmid. The effectiveness of the active agent was verified on ready-to-use vegetables, using either the Lact. casei strain or its culture supernatant fluid as inoculant, compared with cured clone. The application potential of the Lact. casei strain or its culture supernatant fluid for assuring the microbiological safety of ready-to-use vegetables is discussed.

Application of antimicrobial-producing lactic acid bacteria to control pathogens in ready-to-use vegetables

Five psychrotrophic strains of lactic acid bacteria (Lactobacillus casei, Lact. plantarum and Pediococcus spp.) were isolated from 22 samples of commercial salads. These strains were shown to inhibit Aeromonas hydrophila, Listeria monocytogenes, Salmonella typhimurium and Staphylococcus aureus on MRS agar, in salads and in juice prepared from vegetable salads. Lactobacillus casei IMPCLC34 was most effective in reducing total mesophilic bacteria and the coliform group; Aer. hydrophila, Salm. typhimurium and Staph. aureus disappeared after 6 d of storage, while the counts for L. monocytogenes remained constant. The potential application of antimicrobial-producing lactic acid bacteria as biopreservatives of ready-to-use vegetables is suggested.

Inhibitory effect of selected lactic acid bacteria on microflora associated with ready-to-use vegetables

The addition of selected lactic acid bacteria strains had a remarkable inhibitory effect on the growth dynamics of microflora associated with ready-to-use vegetables, during refrigerated storage. In particular, coliforms and enterococci were strongly reduced or eliminated from the products from the third day of storage. Lactobacillus casei strains proved more effective than pediococci. The use of lactic cultures able to produce bacteriocins and to grow at low temperatures could be a useful tool to preserve fresh vegetables and to ensure their microbiological safety.

Antimicrobial compounds from Lactobacillus casei and Lactobacillus helveticus

Three strains of Lactobacillus casei and one of Lactobacillus helveticus were examined for antagonistic activity toward twenty five indicator strains of different species. Under conditions eliminating the effects of organic acid and hydrogen peroxide, culture supernatants of all the Lactobacillus strains exhibited a wide spectrum of inhibitory activity toward microorganisms of different genera. The inhibitory compound secreted by one strain of L. casei was active against Clostridium tyrobutyricum. The active components were insensitive to proteolytic enzyme and heat treatment.

Antagonism and adhesion among isogenic strains of Lactobacillus reuteri in the caecum of gnotobiotic mice

Interactions between a wild adhesive Lactobacillus reuteri strain isolated from chicken crop and its isogenic plasmid-free derivative were studied. Antagonism between these strains was tested in vitro or associated with gnotobiotic mice. The cured strains repressed the establishment of the wild, plasmid bearing strain in the gastrointestinal tract of gnotobiotic mice. Interactions between isogenic strains were independent of the amount of cells administered to mice. The cured derivative strain maintains its specific ability to adhere to epithelial cells of chicken crop.

DNA-free liposome-assisted transfection of Streptococcus faecium SF 77R protoplasts

Two virulent phages of Streptococcus faecium SF 77R were used in DNA-free liposome assisted polyethylene-glycol-mediated protoplast transfection. This procedure, established to develop an effective gene-cloning system, optimized the conditions for DNA uptake by the protoplasts of Str. faecium. Transfection frequencies of up to 10(7)-10(8) P.F.U./microgram of DNA were achieved.

Fast and slow milk-coagulating variants of Lactobacillus helveticus HLM 1

Slow milk-coagulating variants were isolated from Lactobacillus helveticus HLM 1, a fast strain which coagulates milk in 16 h at 42 degrees C. Variants were isolated after subculturing in reconstituted skim milk or complex broth media. Analysis of plasmid content revealed that in slow variants a 3.5-megadalton plasmid was missing.

Drug resistance plasmids in Lactobacillus acidophilus and Lactobacillus reuteri

Sixteen strains of Lactobacillus reuteri and 20 strains of Lactobacillus acidophilus were tested for resistance to 22 antibiotics by using commercially available sensitivity disks. Evidence suggesting linkage of these resistances to plasmids was obtained by "curing" experiments with acridine dyes and high growth temperatures. Examination of plasmid patterns of agarose gel electrophoresis provided further evidence of loss in plasmid DNA under curing conditions in some of the strains examined.