Mycobacterium vaccae Adaptation to Disinfectants and Hand Sanitisers, and Evaluation of Cross-Tolerance with Antimicrobials

The role of veterinary drug use in driving antimicrobial resistance of Staphylococcus aureus isolates in smallholder swine farms in Central Vietnam

Background

Staphylococcus aureus is a well-known opportunistic pathogen widely present in humans and food- producing animals. The emergence of antimicrobial resistance (AMR) in S. aureus represents a major challenge to animal and public health. Poor biosecurity practices and the misuse and overuse of veterinary drugs in farming settings may apply environmental pressure, which favors the selection of AMR bacteria.

Aim

This study aimed to describe veterinary drug usage (VDU), prevalence of AMR phenotypes, and associations among S. aureus isolates from swine of smallholder farms in Central Vietnam.

Methods

A cross-sectional survey was conducted to collect VDU data from smallholder swine farms. A total of 155 nasal swab samples were collected and used for isolating S. aureus. The AMR of S. aureus strains was tested using the disk diffusion method.

Results

Approximately 56.8%, 71.6%, 36.1%, and 69.7% of farmers used vaccines, disinfectants, and antimicrobials (AMs) for prevention and treatment, respectively. Of the 155 nasal swab samples, 99 (63.9%) were positive for S. aureus. Resistance was most commonly observed against oxacillin (59.6%), cefotaxime (59.6%), and linezolid (53.5%). Positive associations were found between the use of vaccines and resistance to oxytetracycline (OR = 3.28, p = 0.01) and povidone usage and resistance to meropenem (OR = 9.35, p = 0.03). Almost all positive associations were observed between the use of AMs (for both prevention and treatment) and AMR in S. aureus. Negative associations were found between resistance to oxytetracycline and the use of gentamicin, linezolid, streptomycin, and norfloxacin.

Conclusion

The present study highlights information on VDU, prevalence, AMR, and their associations with S. aureus isolated from a smallholder swine farm in Central Vietnam. These findings are expected to aid in developing countermeasures against AMR against swine production in Vietnam.

Improving Bioprocess Conditions for the Production of Prodigiosin Using a Marine Serratia rubidaea Strain

The enormous potential attributed to prodigiosin regarding its applicability as a natural pigment and pharmaceutical agent justifies the development of sound bioprocesses for its production. Using a Serratia rubidaea strain isolated from a shallow-water hydrothermal vent, optimization of the growth medium composition was carried out. After medium development, the bacterium temperature, light and oxygen needs were studied, as was growth inhibition by product concentration. The implemented changes led to a 13-fold increase in prodigiosin production in a shake flask, reaching 19.7 mg/L. The conditions allowing the highest bacterial cell growth and prodigiosin production were also tested with another marine strain: S. marcescens isolated from a tide rock pool was able to produce 15.8 mg/L of prodigiosin. The bioprocess with S. rubidaea was scaled up from 0.1 L shake flasks to 2 L bioreactors using the maintenance of the oxygen mass transfer coefficient (kLa) as the scale-up criterion. The implemented parameters in the bioreactor led to an 8-fold increase in product per biomass yield and to a final concentration of 293.1 mg/L of prodigiosin in 24 h.

Evaluation of Pressurized Steam Disinfection of Surfaces Contaminated by Mycobacterium terrae: A Surrogate for Mycobacterium bovis

Introduction

Decontamination of farms affected by bovine tuberculosis could be very challenging during outbreaks occurring in the winter with freezing temperatures. Steam treatment has been of practical interest, but information is needed on whether such treatment is able to inactivate the causative agent, Mycobacterium bovis. This study was to evaluate the use of pressurized steam for inactivation of Mycobacterium terrae, a surrogate for M. bovis on various surfaces.

Methods

Carrier disks made of steel, wood, or rubber were inoculated with 6.32 ± 0.38 log10 M. terrae. While being held at background temperatures of -20°C, 4°C, or 21°C, these carrier disks were treated with pressurized steam (120°C ± 5°C) for 5, 10, 15, or 20 s. Reduction in colony forming units of M. terrae and temperatures on the top and bottom surfaces of the disks were determined.

Results

Complete inactivation of 6 log10 M. terrae on steel and wood disks was achieved by 10 s of steam treatment at all three background temperatures. In comparison, 20 s of steam treatment was needed for the complete inactivation of mycobacteria on rubber disks. Corresponding to the longer treatment time required for mycobacterial inactivation, temperatures on the bottom surface of the rubber disks rose substantially slower than those of the steel and wood disks at all three background temperatures.

Conclusion

The results suggested that treatment with pressurized steam has potential for efficient and effective disinfection of surfaces contaminated by mycobacteria at or below freezing temperatures in winter.

The effect of disinfectants and antiseptics on co- and cross-selection of resistance to antibiotics in aquatic environments and wastewater treatment plants

The outbreak of the SARS-CoV-2 pandemic led to increased use of disinfectants and antiseptics (DAs), resulting in higher concentrations of these compounds in wastewaters, wastewater treatment plant (WWTP) effluents and receiving water bodies. Their constant presence in water bodies may lead to development and acquisition of resistance against the DAs. In addition, they may also promote antibiotic resistance (AR) due to cross- and co-selection of AR among bacteria that are exposed to the DAs, which is a highly important issue with regards to human and environmental health. This review addresses this issue and provides an overview of DAs structure together with their modes of action against microorganisms. Relevant examples of the most effective treatment techniques to increase the DAs removal efficiency from wastewater are discussed. Moreover, insight on the resistance mechanisms to DAs and the mechanism of DAs enhancement of cross- and co-selection of ARs are presented. Furthermore, this review discusses the impact of DAs on resistance against antibiotics, the occurrence of DAs in aquatic systems, and DA removal mechanisms in WWTPs, which in principle serve as the final barrier before releasing these compounds into the receiving environment. By recognition of important research gaps, research needs to determine the impact of the majority of DAs in WWTPs and the consequences of their presence and spread of antibiotic resistance were identified.

Nontuberculous Mycobacterial Resistance to Antibiotics and Disinfectants: Challenges Still Ahead

The mortality incidence from nontuberculous mycobacteria (NTM) infections has been steadily developing globally. These bacterial agents were once thought to be innocent environmental saprophytic that are only dangerous to patients with defective lungs or the immunosuppressed. Nevertheless, the emergence of highly resistant NTM to different antibiotics and disinfectants increased the importance of these agents in the health system. Currently, NTM frequently infect seemingly immunocompetent individuals at rising rates. This is of concern as the resistant NTM are difficult to control and treat. The details behind this NTM development are only beginning to be clarified. The current study will provide an overview of the most important NTM resistance mechanisms to not only antibiotics but also the most commonly used disinfectants. Such evaluations can open new doors to improving control strategies and reducing the risk of NTM infection. Moreover, further studies are crucial to uncover this association.

Rapidly Growing Mycobacterium Species: The Long and Winding Road from Tuberculosis Vaccines to Potent Stress-Resilience Agents

Inflammatory diseases and stressor-related psychiatric disorders, for which inflammation is a risk factor, are increasing in modern Western societies. Recent studies suggest that immunoregulatory approaches are a promising tool in reducing the risk of suffering from such disorders. Specifically, the environmental saprophyte Mycobacterium vaccae National Collection of Type Cultures (NCTC) 11659 has recently gained attention for the prevention and treatment of stress-related psychiatric disorders. However, effective use requires a sophisticated understanding of the effects of M. vaccae NCTC 11659 and related rapidly growing mycobacteria (RGMs) on microbiome–gut–immune–brain interactions. This historical narrative review is intended as a first step in exploring these mechanisms and provides an overview of preclinical and clinical studies on M. vaccae NCTC 11659 and related RGMs. The overall objective of this review article is to increase the comprehension of, and interest in, the mechanisms through which M. vaccae NCTC 11659 and related RGMs promote stress resilience, with the intention of fostering novel clinical strategies for the prevention and treatment of stressor-related disorders.