Campylobacter novaezeelandiae sp. nov., isolated from birds and water in New Zealand.

Six isolates of Campylobacter with similar non-standard colonial morphologies were identified during studies isolating Campylobacter from bird faeces and rivers in New Zealand. Genomic (16S rRNA gene sequencing and whole genome analysis) and phenotypic (MALDI-TOF analysis and conventional biochemical tests) showed that the isolates form a monophyletic clade with genetic relationships to Campylobacter coli/Campylobacter jejuni and Campylobacter peloridis/Campylobacter amoricus. They may be distinguished from other Campylobacter by their MALDI-TOF spectral pattern, their florid α-haemolysis, their ability to grow anaerobically at 37 °C, and on 2 % NaCl nutrient agar, and their lack of hippuricase. This study shows that these isolates represent a novel species within the genus Campylobacter for which the name Campylobacter novaezeelandiae sp. nov. is proposed. The presence of C. novaezeelandiae in water may be a confounder for freshwater microbial risk assessment as they may not be pathogenic for humans. The type strain is B423bT (=NZRM 4741T=ATCC TSD-167T).

Influence of sanitizers on the lipopolysaccharide toxicity of Escherichia coli strains cultivated in the presence of Zygosaccharomyces bailii.

The influence of sublethal concentrations of two sanitizers, liquid iodophor and liquid hypochlorite (LH), on the growth rates and toxicity of food-borne pathogenic Escherichia coli strains grown in the presence of spoilage yeast Zygosaccharomyces bailii was assessed. When grown in combination with Z. bailii both E. coli O113 and E. coli O26 exhibited slower growth rates, except when E. coli O113 was grown in combination with Z. bailii at 0.2% LH. The growth rate of Z. bailii was not impacted by the addition of the sanitizers or by communal growth with E. coli strains. LAL and IL-6 results indicated a decrease in toxicity of pure E. coli cultures with comparable profiles for control and sanitizer exposed samples, although the LAL assay proved to be more sensitive. Interestingly, pure cultures of Z. bailii showed increased toxicity measured by LAL and decreased toxicity measured by IL-6. LAL analysis showed a decrease in toxicity of both E. coli strains grown in combination with Z. bailii, while IL-6 analysis of the mixed cultures showed an increase in toxicity. The use of LAL for toxicity determination in a mixed culture overlooks the contribution made by spoilage yeast, thus demonstrating the importance of using the appropriate method for toxicity testing in mixed microbe environments.

Alicyclobacillus spoilage and isolation--a review.

Until recently, acidic products such as fruit juice and fruit based products were generally thought to be susceptible to spoilage by yeasts, mycelia fungi and lactic acid bacteria, as the low pH of these products acts as natural control measures against spoilage by most bacteria. Alicyclobacillus seem to be prevalent in fruit based products as they survive the acidic fruit juice environment, even when they are exposed to pasteurisation temperatures during production. In this review the historical background of the discovery of these bacteria is summarised. The bacterial characteristics and the reported spoilage incidences caused by members of this genus are discussed. As the isolation methods for these bacteria are controversial, this review includes a discussion of the various media that have been reported in the literature for the use in the isolation and enumeration of members of the genus Alicyclobacillus.

Combining MALDI-TOF and genomics in the study of methicillin resistant and multidrug resistant Staphylococcus pseudintermedius in New Zealand.

Staphylococcus pseudintermedius is an opportunistic and emerging zoonotic pathogen that primarily colonises the skin of dogs. Many common variants are methicillin resistant (MRSP) or multidrug resistant (MDR), and drug resistance is increasingly reported across the globe. In New Zealand, MRSP isolation remains rare in clinics. To pre-emptively inform diagnostic and antimicrobial stewardship practices, we examine isolates of S. pseudintermedius, MRSP and MDR-MRSP from New Zealand dogs using a combination of methodologies. Genetic and genomic data combined with antimicrobial susceptibility screening identify common drug-resistance profiles and their genetic determinants. We demonstrate that sensitive and specific species-level identification of S. pseudintermedius can be achieved using Bruker MALDI-TOF MS and, further, that this technique can be used to identify some common subtype variants, providing a level of categorical precision that falls somewhere between single-locus and multi-locus sequence typing. Comparative genomics analysis of global S. pseudintermedius data shows that MRSP moves frequently across the globe, but that horizontal gene transfer events resulting in the acquisition of the SCCmec cassette (responsible for beta-lactam antibiotic resistance) are infrequent. This suggests that biosecurity and surveillance in addition to antibiotic stewardship should play important roles in mitigating the risk of MRSP, especially in countries such as New Zealand where MRSP is still rare.

Guaiacol production from ferulic acid, vanillin and vanillic acid by Alicyclobacillus acidoterrestris.

Alicyclobacilli are thermophilic, acidophilic bacteria (TAB) that spoil fruit juice products by producing guaiacol. It is currently believed that guaiacol is formed by Alicyclobacillus in fruit juices as a product of ferulic acid metabolism. The aim of this study was to identify the precursors that can be metabolised by Alicyclobacillus acidoterrestris to produce guaiacol and to evaluate the pathway of guaiacol production. A. acidoterrestris FB2 was incubated at 45°C for 7days in Bacillus acidoterrestris (BAT) broth supplemented with ferulic acid, vanillin or vanillic acid, respectively. The samples were analysed every day to determine the cell concentration, the supplement concentration using high performance liquid chromatography with UV-diode array detection (HPLC-DAD) and the guaiacol concentration, using both the peroxidase enzyme colourimetric assay (PECA) and HPLC-DAD. The cell concentration of A. acidoterrestris FB2 during the 7days in all samples were above the critical cell concentration of 10(5)cfu/mL reportedly required for guaiacol production. The guaiacol produced by A. acidoterrestris FB2 increased with an increase in vanillin or vanillic acid concentration and a metabolic pathway of A. acidoterrestris FB2 directly from vanillin to guaiacol was established. The high concentration of vanillic acid (1000mg/L) resulted in an initial inhibitory effect on the cells, but the cell concentration increased after day 2. Guaiacol production did not occur in the absence of either a precursor or A. acidoterrestris FB2 and guaiacol was not produced by A. acidoterrestris FB2 in the samples supplemented with ferulic acid. The presence of Alicyclobacillus spp. that has the ability to produce guaiacol, as well as the substrates vanillin or vanillic acid is prerequisite for production of guaiacol.

Isolation of Alicyclobacillus and the influence of different growth parameters.

Alicyclobacillus species are thermo-acidophilic, endospore-forming bacteria that are able to survive pasteurisation and have been implicated in a number of spoilage incidents involving acidic foods and beverages. The aim of this study was to compare three isolation methods used for the detection of Alicyclobacillus acidoterrestris and to investigate the influence of incubation temperature on the growth of A. acidoterrestris and A. acidocaldarius. Peach juice samples inoculated with A. acidoterrestris K47 were analysed using either the International Federation of Fruit Juice Producers (IFU) Method No. 12 (Method A), which involved spread plating onto Bacillus acidoterrestris (BAT) agar at pH 4.0; Method B, which involved pour plating using potato dextrose agar (PDA) at pH 3.7; or Method C, which made use of membrane filtration followed by incubation on K agar at pH 3.7. The performance of the three methods differed significantly, with the IFU Method No. 12 recovering the highest percentage of cells at 75.97%, followed by Method B at 66.79% and Method C at 3.43%. These findings strengthen the proposal of the IFU for the use of the IFU Method No. 12 as a standard international method for the detection of Alicyclobacillus. To investigate the effect on growth of different incubation temperatures A. acidoterrestris (three strains) and A. acidocaldarius (two strains) were incubated at either 45 °C or 25 °C. Growth at 25°C was slower and maximum cell concentrations were lower (1 x 105-106 cfu/mL compared to 1 x 107-108 cfu/mL) than at 45 °C for A. acidoterrestris. A. acidocaldarius was unable to grow at 25°C and cell concentrations decreased by 1-2 logs. Since a growth temperature of 25 °C could not inhibit growth of A. acidoterrestris, cooling to room temperature (20°-25 °C) is not an effective control measure for A. acidoterrestris inhibition.

Assessing food safety and associated food handling practices in street food vending.

Street vendors in the city of Bloemfontein were investigated in order to assess the microbiological quality of the food being sold as well as the level of hygiene conditions under which these food stalls operate. The food samples which were collected included beef, chicken and gravy, while surface samples were taken from the food preparation tables and the hands of the vendors. A structured questionnaire and checklist were used in interviews to determine the status of the vending sites and associated food handling practices. The overall microbiological quality of the foods served by the street vendors was found to be within acceptable safety limits, although the presence of specific microorganisms such as Escherichia coli, Staphylococcus aureus, Salmonella and yeasts is indicative of a degree of ignorance on the part of the food handlers towards proper hygienic practices.