Biology subjects

Uy, B.

Publications and source records attributed to Uy, B..

4 recordsLinked to original sources

bioRxiv2022

The efficacy of commercial decontamination agents differs between standardised test settings and real-world usage for a variety of bacterial species

Decontamination of surfaces and items plays an important role in reducing the spread of infectious microorganisms in many settings including hospitals and research institutes. Regardless of the location, appropriate decontamination procedures are required for maintaining biosafety and biosecurity. For example, effective decontamination of microbial cultures is essential to ensure proper biocontainment and safety within microbiological laboratories. To this end, many commercial decontamination agents are available which have been tested to a prescribed standard to substantiate their efficacy. However, these standardised tests are unlikely to accurately reflect all conditions encountered in medical and biomedical research. Despite this, laboratory workers and other users of decontamination agents may assume that all decontamination agents will work in all situations. We tested commonly used commercial decontamination agents against a range of bacterial species to determine their efficacy under real-world laboratory conditions. As each decontamination agent has a different recommended dilution for use, to compare their efficacy we calculated their effective ratio which reflects the difference between the manufacturer-recommended dilution and the dilution needed to achieve decontamination under real-world laboratory conditions. Effective ratios above 1 indicate that the agent was active at a dilution more dilute than recommended whereas effective ratios lower than 1 indicate that the agent required a higher concentration than recommended. Our results show that the quaternary ammonium agents TriGene Advance and Chemgene HLD4L were the most active out of the agents tested, with biocidal activity measured at up to 64 times the recommended dilution. In contrast, hypochlorite (bleach) and Prevail (stabilised hydrogen peroxide) had the lowest effective ratios amongst the tested agents. In conclusion, our data suggest that not all decontamination agents will work at the recommended dilutions under real-world laboratory conditions. We recommend that the protocols for the use of decontamination agents are verified under the specific conditions required to ensure they are fit for purpose.

microbiology↗

bioRxiv2017

Natural Colonization of Laboratory Mice with Staphylococcus aureus Primes a Systemic Immune Response

BackgroundWhether mice are an appropriate model for S. aureus infection and vaccination studies is a matter of debate, because they are not considered as natural hosts of S. aureus. Sparked by an outbreak of S. aureus infections in laboratory mice, we investigated whether laboratory mice are commonly colonized with S. aureus and whether this might impact on infection experiments.\n\nMethodsWe characterized 99 S. aureus isolates from laboratory mice (spa typing, virulence gene PCR), and quantified murine antibodies using FlexMap technology.\n\nResultsSpecific-pathogen-free mice from various vendors were frequently colonized with S. aureus (0-21%). S. aureus was readily transmitted from murine parents to offspring, which became persistently colonized. Most murine isolates belonged to the lineage CC88 (54%). Murine strains showed features of host adaptation, such as absence of hlb-converting phages and superantigen genes, as well as enhanced coagulation of murine plasma. Importantly, S. aureus colonization induced a systemic IgG response specific for numerous S. aureus proteins, including several vaccine candidates.\n\nConclusionLaboratory mice are natural hosts of S. aureus and, therefore, provide better infection models than previously assumed. Pre-exposure to S. aureus is a possible confounder in S. aureus infection and vaccination studies.

immunology↗

bioRxiv2016

A novel restraint device for injection of Galleria mellonella larvae that minimises the risk of accidental operator needle stick injury

Larvae of the insect Galleria mellonella are increasingly being used for studying pathogenic microbes and their virulence mechanisms, and as a rapid model for screening novel antimicrobial agents. The larvae (waxworms) are most frequently infected by injection of pathogenic organisms into the haemocoel through the insects prolegs. The mostly widely used method for restraining the waxworms for injection is by grasping them between the operators fingers, which puts the operator at risk of needle stick injury, an important consideration when working with highly pathogenic and/or drug-resistant microorganisms. While use of a stab proof glove can reduce this risk of injury, it does so at the loss of manual dexterity and speed, resulting in a more labour-intensive and cumbersome assay. We describe a simple cost effective device (the so-called Galleria Grabber) for restraining waxworms for injection that keeps the operators fingers clear of the needle thus reducing the risk of injury.

microbiology↗

bioRxiv2016

Effect of common and experimental anti-tuberculosis treatments on Mycobacterium tuberculosis growing as biofilms

Much is known regarding the antibiotic susceptibility of planktonic cultures of Mycobacterium tuberculosis, the bacterium responsible for the lung disease tuberculosis (TB). As planktonically-grown M. tuberculosis are unlikely to be entirely representative of the bacterium during infection, we set out to determine how effective a range of anti-mycobacterial treatments were against M. tuberculosis growing as a biofilm, a bacterial phenotype known to be more resistant to antibiotic treatment. Light levels from bioluminescently-labelled M. tuberculosis H37Rv (strain BSG001) were used as a surrogate for bacterial viability, and were monitored before and after 1 week of treatment. After treatment, biofilms were disrupted, washed and inoculated into fresh broth and plated onto solid media to rescue any surviving bacteria. We found that in this phenotypic state M. tuberculosis was resistant to the majority of the compounds tested. Minimum inhibitory concentrations (MICs) increased by 20-fold to greater than 1000-fold, underlying the potential of this phenotype to cause significant problems during treatment.

microbiology↗