scholarly journals Evaluation of F-Specific RNA Bacteriophage as a Candidate Human Enteric Virus Indicator for Bivalve Molluscan Shellfish

2000 ◽  
Vol 66 (4) ◽  
pp. 1280-1285 ◽  
Author(s):  
William J. Doré ◽  
Kathleen Henshilwood ◽  
David N. Lees
Keyword(s):  
Disease Outbreaks ◽  
Enteric Virus ◽  
Seasonal Trend ◽  
Human Consumption ◽  
Point Of Sale ◽  
E Coli ◽  
Reverse Transcription Pcr ◽  
The United Kingdom ◽  
Viral Indicators ◽  
A Site

ABSTRACT Escherichia coli is a widely utilized indicator of the sanitary quality of bivalve molluscan shellfish sold for human consumption. However, it is now well documented that shellfish that meet the E. coli standards for human consumption may contain human enteric viruses that cause gastroenteritis and hepatitis. In this study we investigated using F-specific RNA bacteriophage (FRNA bacteriophage) to indicate the likely presence of such viruses in shellfish sold for consumption. FRNA bacteriophage and E. coli levels were determined over a 2-year period for oysters (Crassostrea gigas) harvested from four commercial sites chosen to represent various degrees of sewage pollution. Three sites were classified as category B sites under the relevant European Community (EC) Directive (91/492), which required purification (depuration) of oysters from these sites before sale. One site was classified as a category A site, and oysters from this site could be sold directly without further processing. Samples were tested at the point of sale following commercial processing and packaging. All of the shellfish complied with the mandatory EC E. coli standard (less than 230 per 100 g of shellfish flesh), and the levels of contamination for more than 90% of the shellfish were at or below the level of sensitivity of the assay (20 E. coli MPN per 100 g), which indicated good quality based on this criterion. In contrast, FRNA bacteriophage were frequently detected at levels that exceeded 1,000 PFU per 100 g. High levels of FRNA bacteriophage contamination were strongly associated with harvest area fecal pollution and with shellfish-associated disease outbreaks. Interestingly, FRNA bacteriophage contamination exhibited a marked seasonal trend that was consistent with the trend of oyster-associated gastroenteritis in the United Kingdom. The correlation between FRNA bacteriophage contamination and health risk was investigated further by using a reverse transcription-PCR assay for Norwalk-like virus (NLV). NLV contamination of oysters was detected only at the most polluted site and also exhibited a seasonal trend that was consistent with the trend of FRNA bacteriophage contamination and with the incidence of disease. The results of this study suggest that FRNA bacteriophage could be used as viral indicators for market-ready oysters.

Functional and Structural Characterization of Acquired Pan-Aminoglycoside Resistance 16S rRNA Methyltransferase NpmB1

2021 ◽  
Author(s):  
Akito Kawai ◽  
Masahiro Suzuki ◽  
Kentaro Tsukamoto ◽  
Yusuke Minato ◽  
Yohei Doi
Keyword(s):  
Amino Acid ◽  
16S Rrna ◽  
Amino Acid Identity ◽  
Single Amino Acid ◽  
Aminoglycoside Resistance ◽  
E Coli ◽  
The United Kingdom ◽  
Amino Acid Variant ◽  
A Site

Post-translational methylation of the A site of 16S rRNA at position A1408 leads to pan-aminoglycoside resistance encompassing both 4,5- and 4,6-disubstituted 2-deoxystreptamine (DOS) aminoglycosides. To date, NpmA is the only acquired enzyme with such function. Here, we present function and structure of NpmB1 whose sequence was identified in Escherichia coli genomes registered from the United Kingdom. NpmB1 possesses 40% amino acid identity with NpmA1 and confers resistance to all clinically relevant aminoglycosides including 4,5-DOS agents. Phylogenetic analysis of NpmB1 and NpmB2, its single amino acid variant, revealed that the encoding gene was likely acquired by E. coli from a soil bacterium. The structure of NpmB1 suggests that it requires a structural change of the β6/7 linker in order to bind to 16S rRNA. These findings establish NpmB1 and NpmB2 as the second group of acquired pan-aminoglycoside resistance 16S rRNA methyltransferases.

scholarly journals Microbiological Quality of Kachumbari, a Raw Vegetable Salad Popularly Served Alongside Roast Meat in Kenya

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Kenneth M. Mbae ◽  
Mercy K. Ndwiga ◽  
Fredrick G. Kiruki
Keyword(s):  
Cross Section ◽  
Microbiological Quality ◽  
Disease Outbreaks ◽  
Human Consumption ◽  
Microbial Quality ◽  
Protection Agency ◽  
Indicator Microorganisms ◽  
E Coli ◽  
Food Borne

Raw salads are regularly implicated in food-borne disease outbreaks globally. Consumption of kachumbari, a raw vegetable salad, alongside roast meat is widespread in Kenya. The aim of this study was to evaluate the bacteriological quality of kachumbari samples (n=39) collected from a cross section of roasted meat eateries in Kenya. The United Kingdom’s Health Protection Agency guidelines were used to infer safety of the salads due to lack of local criteria for microbiological safety of ready-to-eat fresh produce placed in the market. Based on Escherichia coli counts, 14 (35.9%) of the samples were of satisfactory microbial quality (<20 CFU/g), 7 (17.9%) in the borderline (20–≤102 CFU/g), and 18 (46.2%) unsatisfactory (>102 CFU/g). All samples examined for staphylococci had counts falling within the borderline range (20–≤104 CFU/g). Collectively, 3 (7.7%) of the sampled salads were classified as potentially harmful to health and/or unfit for human consumption due to the presumptive presence of 2 (5.1%) Campylobacter spp. and 1 (2.6%) E. coli O157. Salmonella was not detected in any of the samples. The presence of hygiene indicator microorganisms and pathogens demonstrates that kachumbari salads present a public health risk.

Characterisation of multidrug resistant Escherichia coli isolated from two commercial lettuce and spinach supply chains

2021 ◽  
Author(s):  
Muneiwa T. Ratshilingano ◽  
Erika Margarete du Plessis ◽  
Stacey Duvenage ◽  
Lise Korsten
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Irrigation Water ◽  
Virulence Genes ◽  
Disease Outbreaks ◽  
Virulence Gene ◽  
Multidrug Resistant ◽  
Water Sources ◽  
Point Of Sale ◽  
E Coli

ABSTRACT Leafy green vegetables have increasingly been reported as a reservoir of multidrug-resistant pathogenic Enterobacteriaceae; with Shiga toxin- producing Escherichia coli frequently implicated in disease outbreaks worldwide.  This study aimed to determine the presence and characteristics of antibiotic resistance, diarrheagenic virulence genes and phylogenetic groupings of E. coli isolates (n=51) from commercially produced lettuce and spinach from the farm, through processing and at the point of sale.  Multidrug resistance was observed in 33 of the 51 E. coli isolates (64.7%); with 35.7% (n=10/28) being generic and 100% (n=23/23) Extended Spectrum β-lactamase/AmpC- producing.  Resistance of E. coli isolates was observed against neomycin (100%; n=51/51), ampicillin (70.6%; n=36/51), amoxycilin (68.6%; n=35/51), tetracycline (45%; n=23/51), trimethoprim/ sulfamethoxazole (43%; n=22/51), chloramphenicol (25.5%; n=13/51), augmentin (11.8%; n=6/51) and gentamicin (7.8%; n=4/51); with 100% (n=51/51) susceptibility to imipenem. Virulence gene eae was detected in two E. coli isolates from irrigation water sources only, while none of the other virulence genes tested for were detected.   Most of the E. coli strains belonged to phylogenetic group B2 (25.5%; n=13), B1 (19.6%; n=10) and A (17.6%; n=9); with D (5.9%; n=3) less distributed. Although diarrheagenic E. coli were not detected, antibiotic resistance in E. coli prevalent in the supply chain was evident. Additionally, a clear link between E. coli isolates from irrigation water sources and leafy green vegetables through DNA fingerprinting was established which indicates the potential transfer of E. coli from irrigation water to minimally processed leafy green vegetables.

Determination of Norovirus Contamination in Oysters from Two Commercial Harvesting Areas over an Extended Period, Using Semiquantitative Real-Time Reverse Transcription PCR

2008 ◽  
Vol 71 (7) ◽  
pp. 1427-1433 ◽  
Author(s):  
JAMES A. LOWTHER ◽  
KATHLEEN HENSHILWOOD ◽  
DAVID N. LEES
Keyword(s):  
Human Health Risk ◽  
Extended Period ◽  
Epidemiological Data ◽  
Indicator Organisms ◽  
Fecal Indicator ◽  
E Coli ◽  
Reverse Transcription Pcr ◽  
The United Kingdom ◽  
Male Specific ◽  
Production Areas

The human health risk associated with the consumption of molluscan shellfish grown in sewage-contaminated waters is well established. Noroviruses, which cause gastroenteritis, are the principal agents of shellfish-related illness. Fecal-indicator quality standards based on Escherichia coli are well established in Europe and elsewhere. However, norovirus outbreaks after consumption of shellfish meeting these standards still occur, and the need to improve consumer health protection is well recognized. Alternative approaches proposed include direct monitoring of viral pathogens and the use of alternative indicator organisms capable of providing a better indication of virus risk. This study applies a recently developed TaqMan PCR assay to assess norovirus contamination in shellfish. Comparison was made with E. coli as the existing sanitary standard and a male-specific RNA bacteriophage as a possible alternative. Two commercial pacific oyster (Crassostrea gigas) harvesting areas were monitored over a 31-month period. The results show peaks of norovirus contamination in both areas during winter months, with average levels approximately 17 times higher in oysters sampled October to March than during the remainder of the year, consistent with epidemiological data for the United Kingdom showing oyster-associated illness is confined to winter months. While there was no apparent association with E. coli, an association between levels of norovirus contamination and the male-specific RNA bacteriophage was noted, with average norovirus levels over 40 times higher in samples with male-specific RNA bacteriophage counts of &gt;1,000 PFU/100 g than in samples with &lt;100 PFU/100 g. Overall, these results suggest that norovirus monitoring in shellfish production areas could be an effective strategy for reduction of virus risk.

The Microbiological Quality of Cooked Rice from Restaurants and Take-Away Premises in the United Kingdom

1999 ◽  
Vol 62 (8) ◽  
pp. 877-882 ◽  
Author(s):  
G. L. NICHOLS ◽  
C. L. LITTLE ◽  
V. MITHANI ◽  
J. de LOUVOIS
Keyword(s):  
United Kingdom ◽  
Microbiological Quality ◽  
Point Of Sale ◽  
E Coli ◽  
Cooked Rice ◽  
The United Kingdom ◽  
Bacillus Spp ◽  
Rice Samples ◽  
The Uk

The microbiological quality of 4,162 samples of cooked rice from restaurants and take-away premises in the United Kingdom was examined, including ready-to-eat rice purchased at point-of-sale and rice that was stored precooked for reheating on demand. The majority of point-of-sale cooked rice samples (1,855 of 1,972; 94%) were of acceptable microbiological quality, but 15 (1%) samples were of unacceptable quality (Bacillus spp. and B. cereus, ≥105 CFU/g; Escherichia coli, ≥104 CFU/g), indicating a potential risk to health. The prevalence of Bacillus spp., B. cereus, and E. coli was significantly greater in precooked stored rice than in point-of-sale cooked rice (P &lt; 0.005 to 0.0005). Bacillus spp. (≥104 CFU/g), B. cereus (≥104 CFU/g), and E. coli (≥102 CFU/g) were present in 7%, 2%, and 9% of precooked stored samples, respectively, compared to 2%, 0.5%, and 1%, respectively in point-of-sale samples. Although final heating at the point of sale reduces the levels of microorganisms present in rice it will not inactivate the B. cereus emetic toxin if present. Rice from Indian premises was of poorer microbiological quality than that from Chinese and other premises. Although most point-of-sale cooked rice samples (94%) were of an acceptable microbiological quality, evidence from this study indicates that the microbiological quality of cooked rice sold from certain outlets in the UK is of concern.

Application of RtcB ligase to monitor self-cleaving ribozyme activity by RNA-seq

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
V. Janett Olzog ◽  
Lena I. Freist ◽  
Robin Goldmann ◽  
Jörg Fallmann ◽  
Christina E. Weinberg
Keyword(s):  
Rna Seq ◽  
Site Specific ◽  
Pyrococcus Horikoshii ◽  
Total Rna ◽  
E Coli ◽  
Catalytic Rnas ◽  
Adapter Ligation ◽  
Domains Of Life ◽  
Cyclic Phosphate ◽  
A Site

Abstract Self-cleaving ribozymes are catalytic RNAs and can be found in all domains of life. They catalyze a site-specific cleavage that results in a 5′ fragment with a 2′,3′ cyclic phosphate (2′,3′ cP) and a 3′ fragment with a 5′ hydroxyl (5′ OH) end. Recently, several strategies to enrich self-cleaving ribozymes by targeted biochemical methods have been introduced by us and others. Here, we develop an alternative strategy in which 5ʹ OH RNAs are specifically ligated by RtcB ligase, which first guanylates the 3′ phosphate of the adapter and then ligates it directly to RNAs with 5′ OH ends. Our results demonstrate that adapter ligation to highly structured ribozyme fragments is much more efficient using the thermostable RtcB ligase from Pyrococcus horikoshii than the broadly applied Escherichia coli enzyme. Moreover, we investigated DNA, RNA and modified RNA adapters for their suitability in RtcB ligation reactions. We used the optimized RtcB-mediated ligation to produce RNA-seq libraries and captured a spiked 3ʹ twister ribozyme fragment from E. coli total RNA. This RNA-seq-based method is applicable to detect ribozyme fragments as well as other cellular RNAs with 5ʹ OH termini from total RNA.

A Comparison of Hand Washing Techniques To Remove Escherichia coli and Caliciviruses under Natural or Artificial Fingernails

2003 ◽  
Vol 66 (12) ◽  
pp. 2296-2301 ◽  
Author(s):  
CHIA-MIN LIN ◽  
FONE-MAO WU ◽  
HOI-KYUNG KIM ◽  
MICHAEL P. DOYLE ◽  
BARRY S. MICHAELS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Tap Water ◽  
Hand Washing ◽  
Microbial Populations ◽  
Liquid Soap ◽  
E Coli ◽  
Hand Sanitizer ◽  
Before And After ◽  
Escherichia Coli Jm109 ◽  
Viral Indicators

Compared with other parts of the hand, the area beneath fingernails harbors the most microorganisms and is most difficult to clean. Artificial fingernails, which are usually long and polished, reportedly harbor higher microbial populations than natural nails. Hence, the efficacy of different hand washing methods for removing microbes from natural and artificial fingernails was evaluated. Strains of nonpathogenic Escherichia coli JM109 and feline calicivirus (FCV) strain F9 were used as bacterial and viral indicators, respectively. Volunteers with artificial or natural nails were artificially contaminated with ground beef containing E. coli JM109 or artificial feces containing FCV. Volunteers washed their hands with tap water, regular liquid soap, antibacterial liquid soap, alcohol-based hand sanitizer gel, regular liquid soap followed by alcohol gel, or regular liquid soap plus a nailbrush. The greatest reduction of inoculated microbial populations was obtained by washing with liquid soap plus a nailbrush, and the least reduction was obtained by rubbing hands with alcohol gel. Lower but not significantly different (P &gt; 0.05) reductions of E. coli and FCV counts were obtained from beneath artificial than from natural fingernails. However, significantly (P ≤ 0.05) higher E. coli and FCV counts were recovered from hands with artificial nails than from natural nails before and after hand washing. In addition, microbial cell numbers were correlated with fingernail length, with greater numbers beneath fingernails with longer nails. These results indicate that best practices for fingernail sanitation of food handlers are to maintain short fingernails and scrub fingernails with soap and a nailbrush when washing hands.

scholarly journals The effect of activation of the lactoperoxidase system and souring on certain potential human pathogens in cows' milk

1997 ◽  
Vol 68 (4) ◽  
Author(s):  
J.G.K. Kangumba ◽  
E.H. Venter ◽  
J.A.W. Coetzer
Keyword(s):  
Rural Communities ◽  
Alternative Methods ◽  
Human Consumption ◽  
Socioeconomic Conditions ◽  
Human Pathogens ◽  
Pathogenic Potential ◽  
E Coli ◽  
Lactoperoxidase System ◽  
Potential Alternative ◽  
System Activation

Conventional methods of ensuring the safety and soundness of cows' milk for human consumption, such as pasteurisation, are not always practical in poor socioeconomic conditions or in rural communities that lack modern amenities. Activation of lactoperoxidase (LP) system and souring of milk were investigated as potential alternative methods to sustain the safety of milk by inhibiting certain microorganisms with known pathogenic potential. The activation of the LP-system inhibited the growth of Staphylococcus aureus and Escherichia coli by the order of 2 log values. The inhibition of Brucella abortus was negligible. The replication of Coxiella burnetti in milk was not disturbed even after 17 h of LP-system activation at 20 oC, but the outcome of the LP-system treatment on Mycobacterium bovis could not be determined as the conventional culturing technique used to grow this organism did not allow full recovery. Souring inhibited the growth of S. aureus and E. coli also by the order of 2 log values. From the results obtained in this investigation are concluded that the activation of the LP-system and souring can be used to inhibit the growth of S. aureus and E. coli in cows' milk, thereby increasing its safety.

The use of antibiotic resistance profiling as a means of tracing sources of fecal contamination in source waters

2010 ◽  
Vol 10 (2) ◽  
pp. 209-215
Author(s):  
M. S. Mthembu ◽  
P. T. Biyela ◽  
T. G. Djarova ◽  
A. K. Basson
Keyword(s):  
Antibiotic Resistance ◽  
Municipal Wastewater ◽  
Fecal Contamination ◽  
Source Tracking ◽  
Human Consumption ◽  
Biochemical Tests ◽  
Isolation And Identification ◽  
E Coli ◽  
Intestinal Pathogens ◽  
Source Waters

Fecal contamination of source waters and its associated intestinal pathogens continues to pose risks to public health although the extent and effect of microbial contamination of source waters gets very little attention in designing treatment plants in most developing countries. Coliform counts give an indication of the overall bacterial contamination of water and thus its safety for human consumption. However, their presence fails to provide information about the source of fecal contamination which is vital to managing fecal contamination problems in surface waters. This study explored the use of multiple antibiotic resistance (MAR) indexing as means of differentiating E. coli isolates from different sources. A total of 322 E. coli isolates were obtained from municipal wastewater and from fecal samples from domestic and wild animals. Conventional culture methods and standard chemical and biochemical tests were used for isolation and identification of E. coli. Isolates were assayed against 10 antibiotics using the micro-dilution technique. The results obtained generated antibiotic resistance profiles which were used to statistically group the isolates into different subsets. Correct source classification was obtained for 60% of human-derived and 95% non-human-derived E. coli respectively. These results indicate the validity of the usefulness of MAR indexing as a method of bacterial source tracking.

Hollow-Fiber Ultrafiltration for the Concentration and Simultaneous Recovery of Multiple Pathogens in Contaminated Foods

2009 ◽  
Vol 72 (12) ◽  
pp. 2547-2552 ◽  
Author(s):  
HEE-YEON KIM ◽  
HYEUN-JIN PARK ◽  
GWANGPYO KO
Keyword(s):  
Hollow Fiber ◽  
Food Samples ◽  
Murine Norovirus ◽  
Viral Pathogens ◽  
Recovery Rates ◽  
Total Recovery ◽  
E Coli ◽  
Reverse Transcription Pcr ◽  
Elution Buffer ◽  
Multiple Pathogens

We investigated the possibility of using hollow-fiber ultrafiltration (HUF) for the simultaneous recovery of multiple microorganisms in food samples. MS2 bacteriophage, E. coli, Bacillus subtilis spores, and murine norovirus (MNV) were each inoculated into 5 liters of either distilled water (DW) or glycine elution buffer and then concentrated using hollow-fiber polysulfone ultrafilters. The resulting concentrates were further analyzed by either cultivation or TaqMan real-time reverse transcription PCR assay. The overall average recovery rates were 7.1% in DW and 17.1% in glycine elution buffer. When the virus, vegetative bacteria, and bacterial spores were simultaneously inoculated into DW, glycine, or Tris-HCl elution buffers, on average 16.8% of inoculated microorganisms were recovered by HUF. The addition of 3% beef extract blocking buffer to HUF increased the total recovery rate to 46.1%, with incremental recovery rates increasing sharply for B. subtilis spores and MNV. Use of HUF resulted in E. coli recovery rates of 68.0% on lettuce and 66.2% on ham and MNV recovery rates of 1.5% on lettuce and 5.8% on ham. Our study demonstrates that HUF can be effective at simultaneously recovering and concentrating diverse bacterial and viral pathogens from foods.

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