Inhibition of Clostridium botulinum by strains of Clostridium perfringens isolated from soil

Cellular and population strategies underpinning neurotoxin production and sporulation in Clostridium botulinum type E cultures

IMPORTANCE

Toxin production and sporulation are key determinants of pathogenesis in Clostridia. Toxins cause the clinical manifestation of clostridial diseases, including diarrhea and colitis, tissue damage, and systemic effects on the nervous system. Spores ensure long-term survival and persistence in the environment, act as infectious agents, and initiate the host tissue colonization leading to infection. Understanding the interplay between toxin production and sporulation and their coordination in bacterial cells and cultures provides novel intervention points for controlling the public health and food safety risks caused by clostridial diseases. We demonstrate environmentally driven cellular heterogeneity in botulinum neurotoxin and spore production in Clostridium botulinum type E populations and discuss the biological rationale of toxin and spore production in the pathogenicity and ecology of C. botulinum. The results invite to reassess the epidemiology of botulism and may have important implications in the risk assessment and risk management strategies in food processing and human and animal health.

Microbial community origin and fate through a rural wastewater treatment plant

Conventional wastewater treatment relies on a complex microbiota; however, much of this community is still to be characterised. To better understand the origin, dynamics and fate of bacteria within a wastewater treatment plant: untreated primary wastewater, activated sludge, and post-treatment effluent were characterised. From 3,163 Exact Sequence Variants (ESVs), 860 were annotated to species-level. In primary wastewater, 28% of ESVs were putative bacterial species previously associated with humans, 14% with animals and 5% as common to the environment. Differential abundance analysis revealed significant relative reductions in ESVs from potentially humans-associated species from primary wastewater to activated sludge, and significant increases in ESVs from species associated with nutrient cycling. Between primary wastewater and effluent, 51% of ESVs from human-associated species did not significantly differ, and species such as Bacteroides massiliensis and Bacteroides dorei increased. These findings illustrate that activated sludge increased extracellular protease and urease-producing species, ammonia and nitrite oxidizers, denitrifiers and specific phosphorus accumulators. Although many human-associated species declined, some persisted in effluent, including strains of potential health or environmental concern. Species-level microbial assessment may be useful for understanding variation in wastewater treatment efficiency as well as for monitoring the release of microbes into surface water and the wider ecosystem. This article is protected by copyright. All rights reserved.

The First Identification and Antibiogram of Clostridium perfringens Type C Isolated from Soil and The Feces of Dead Foals in South Korea

Simple Summary

Clostridium (C.) perfringens in horses causes acute enteritis and death, but research on C. perfringens in South Korea is virtually nonexistent. The purpose of this study was to discover the cause of death of numerous South Korean foals. C. perfringens was isolated from 25 (11.1%) of 225 sampled horses and from 16 (35.56%) of 45 farms investigated in this study. Of the 25 C. perfringens isolates, 15 (60%) were type A and 10 (40%) were type C. Type C was observed on all the farms where the foals’ deaths occurred. The antimicrobial susceptibility test was performed using MIC (Minimum Inhibitory Concentration) Evaluator strips test. These results are the first to identify one of the causes of acute foal death in South Korea and can be used as a criterion to determine the cause of acute foal death and to select effective antibiotics.

Abstract

Clostridium (C.) perfringens was isolated from 25 (11.1%) of 225 sampled horses and from 16 (35.56%) of 45 farms. All of the samples were negative for cpe,etx, itx, NetF genes and cpagene were detected in 100% (25 of 25) of the samples that were positive for C. perfringens. cpb and cpb2 were detected in 40.0% (10 of 25) and 60.0% (15 of 25) of the samples that were positive for C. perfringens, respectively. Of the 25 C. perfringens isolates, 15 (60%) were type A and 10 (40%) were type C. Type C was observed on all the farms where the foals’ deaths occurred. None of the isolates were positive for type B, type D, or type E. The MIC Evaluator strips antimicrobial susceptibility test showed meropenem (96%), ampicillin (92%), amoxicillin/clavulanic acid (84%), and tetracycline (8%) sensitivity.

Clostridium Perfringens Spores in Polish Honey Samples

Introduction

The aim of this study was examination of honey samples collected from apiaries situated in all Polish provinces for occurrence of Clostridium spp., especially C. perfringens.

Material and Methods

The study was carried out on 240 honey samples (15 samples/province). Estimation of Clostridium titre, its cultures and C. perfringens isolate characterisation were performed according to the standard PN-R-64791:1994. A multiplex PCR method for detection of genes coding cpa (α toxin), cpb (β), cpb2 (β2), etx (ε), iap (ι), and cpe (enterotoxin) toxins was used.

Results

Clostridium spp. was noticed in 56% (136/240) of samples, and its titres ranged between 0.1 g and 0.001 g. Clostridium perfringens occurrence was evidenced in 27.5% (66/240) of samples. All isolates were classified to toxinotype A.

Conclusions

Evidence of a high number of positive samples with occurrence of Clostridium spp. indicates a potential risk to consumers’ health. The infective number of Clostridium spp. is unknown; however, the obtained results have shown that a risk assessment on the entire honey harvesting process should be made in order to ensure microbiological safety. Moreover, a detailed study should be undertaken on the antibiotic resistance of C. perfringens isolates from honey samples.

Botulism outbreaks in natural environments - an update

Clostridium botulinum comprises a diverse group of botulinum toxin-producing anaerobic rod-shaped spore-forming bacteria that are ubiquitously distributed in soils and aquatic sediments. Decomposition of plants, algae, and animals creates anaerobic environments that facilitate growth of C. botulinum, which may then enter into food webs leading to intoxication of animals. Via saprophytic utilization of nutrients, the bacteria rapidly sporulate, creating a reservoir of highly robust spores. In the present review, we focus on the occurrence of C. botulinum in non-clinical environments, and examine factors influencing growth and environmental factors associated with botulism outbreaks. We also outline cases involving specific environments and their biota. In wetlands, it has been found that some C. botulinum strains can associate with toxin-unaffected organisms–-including algae, plants, and invertebrates–-in which the bacteria appear to germinate and stay in the vegetative form for longer periods of time. We suggest the need for future investigations to resolve issues related to the environments in which C. botulinum spores may accumulate and germinate, and where the vegetative forms may multiply.

New composite nitrite-free and low-nitrite meat-curing systems using natural colorants

Nitrite-free and low-nitrite meat-curing systems were developed to eliminate or reduce nitrite in frankfurter-type sausages. Different composite meat-curing mixtures were formulated using cochineal and paprika as natural colorants, sodium hypophosphite (SHP) as antimicrobial agent, butylated hydroxyanisole (BHA) as antioxidant and sodium nitrite. The treatment, which contained 0.015% cochineal, most closely resembled the 120 ppm NaNO2 in its ability to create cured-meat color. BHA was found to be a strong antioxidant at the 30 ppm level in cooked sausages during refrigerated storage for 5 weeks. All treatments containing 40 ppm sodium nitrite were successful in replicating sensory attributes of frankfurter samples. Our findings support the use of SHP as possible antibotulinal agent in nitrite-free meat-curing systems.

Development and application of a new method for specific and sensitive enumeration of spores of nonproteolytic Clostridium botulinum types B, E, and F in foods and food materials

The highly potent botulinum neurotoxins are responsible for botulism, a severe neuroparalytic disease. Strains of nonproteolytic Clostridium botulinum form neurotoxins of types B, E, and F and are the main hazard associated with minimally heated refrigerated foods. Recent developments in quantitative microbiological risk assessment (QMRA) and food safety objectives (FSO) have made food safety more quantitative and include, as inputs, probability distributions for the contamination of food materials and foods. A new method that combines a selective enrichment culture with multiplex PCR has been developed and validated to enumerate specifically the spores of nonproteolytic C. botulinum. Key features of this new method include the following: (i) it is specific for nonproteolytic C. botulinum (and does not detect proteolytic C. botulinum), (ii) the detection limit has been determined for each food tested (using carefully structured control samples), and (iii) a low detection limit has been achieved by the use of selective enrichment and large test samples. The method has been used to enumerate spores of nonproteolytic C. botulinum in 637 samples of 19 food materials included in pasta-based minimally heated refrigerated foods and in 7 complete foods. A total of 32 samples (5 egg pastas and 27 scallops) contained spores of nonproteolytic C. botulinum type B or F. The majority of samples contained <100 spores/kg, but one sample of scallops contained 444 spores/kg. Nonproteolytic C. botulinum type E was not detected. Importantly, for QMRA and FSO, the construction of probability distributions will enable the frequency of packs containing particular levels of contamination to be determined.

Growth and toxigenesis of C. botulinum type E in fishes packaged under modified atmospheres

Modified atmosphere packaging of fresh fish is used to market high quality products in some European countries. The potential risk of C. botulinum growth in these extended shelf-life foods is still a concern; especially since toxigenesis may precede organoleptic spoilage. This paper will present toxigenic data from rockfish, salmon and sole muscle tissues which were inoculated with a pool of non-proteolytic C. botulinum type E at seven levels (10(-2)-10(4) spores/sample), and stored under vacuum and 100% CO2, at incubation temperatures between 30 and 4 degrees C, for up to 60 days. Factorial experimental design allowed predictive formulae to be developed able to describe the lag time prior to C. botulinum toxigenesis and the probability of one spore to initiate toxigenesis based upon the storage conditions. Accurate characterization of the microbial ecology of C. botulinum in modified atmosphere-packaged fish, will support safe exploitation of these packaging systems in the market place, and identify critical control points for potential product or process abuses.

Clostridium botulinum in aquatic environments in Great Britain and Ireland

Mud samples from aquatic environments in many parts of Great Britain and Ireland were collected, mainly in 1975 and 1976, and examined for Clostridium botulinum. The samples were taken from lakes, ponds, reservoirs, marshes, mudflats, streams, rivers and canals, and the sampling areas included a number of bird refuges and reserves. Of 554 samples 194 (35.0%) were positive and 167 (30.1%), 19 (3.4%), 6 (1.1%) and 15 (2.7%) contained types B, C, D and E respectively; 13 (2.3%) contained more than one type. Each type demonstrated was found in both fresh-and salt-water environments. Type B was widespread; types C, D and E were demonstrated in widely separated areas in England and Wales, and type C was found in both the north and south of Scotland. The results were compared with those reported earlier in respect of surveys in the London area, the Norfolk Boads and the Camargue (France).