What Is the Appropriate Meropenem MIC for Screening of Carbapenemase-Producing Enterobacteriaceae in Low-Prevalence Settings?

Infection with carbapenemase-producingEnterobacteriaceae(CPE) has been shown to cause significant illness among hospitalized patients. Given the paucity of treatment options, there is a critical need to stop the spread of CPE. However, screening for the presence of CPE in laboratory settings has been challenging. In order to assess the effectiveness of current CPE detection guidelines, we analyzed the meropenem MIC distribution for a large set of clinicalEnterobacteriaceaeisolates. A total of 1,022 isolates submitted to the Public Health Ontario Laboratories (PHOL) from January 2011 to March 2014 were examined. Only isolates displaying a meropenem or ertapenem MIC of ≥0.25 or ≥1 μg/ml, respectively, were included. Carbapenemase-positive isolates were identified by multiplex PCR. We identified 189 isolates positive for carbapenemases, which primarily comprised NDM, KPC, and OXA-48-like carbapenemases, and these isolates were largelyKlebsiellaspp.,Escherichia coli, andEnterobacterspp. Interestingly, 14 to 20% of these isolates displayed meropenem MICs within the susceptible range on the basis of CLSI and EUCAST breakpoint interpretive criteria. While the majority of meropenem-susceptible CPE isolates were observed to beE. coli, meropenem susceptibility was not exclusive to any one species/genus or carbapenemase type. Application of CLSI screening recommendations captured only 86% of carbapenemase-producing isolates, whereas application of EUCAST recommendations detected 98.4% of CPE isolates. In a region with a low carbapenemase prevalence, meropenem-based screening approaches require a cutoff MIC near the epidemiological wild-type threshold in order to achieve nearly optimal CPE identification.

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Fecal Metagenome Sequences from Lactating Dairy Cows Shedding Escherichia coli O157:H7

Microbiology Resource Announcements ◽

10.1128/mra.01279-18 ◽

2018 ◽

Vol 7 (18) ◽

Author(s):

Serajus Salaheen ◽

Seon Woo Kim ◽

Jeffrey S. Karns ◽

Bradd J. Haley ◽

Jo Ann S. Van Kessel

Keyword(s):

Escherichia Coli ◽

Dairy Cows ◽

Causative Agent ◽

Public Domain ◽

Escherichia Coli O157 ◽

Content Type ◽

The Public ◽

E Coli ◽

Lactating Dairy Cows ◽

Human Infections

Cattle are primary reservoirs of Escherichia coli O157:H7, a causative agent of severe human infections. To facilitate analyses of the communities in which this pathogen is found, we sequenced the fecal metagenomes of 10 dairy cows shedding E. coli O157:H7 and added them to the public domain.

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Cold Shock Induces Chromosomal qnr in Vibrio Species and Plasmid-Mediated qnrS1 in Escherichia coli

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01472-19 ◽

2019 ◽

Vol 63 (12) ◽

Author(s):

Hee-Chang Jang ◽

Yin Wang ◽

Chunhui Chen ◽

Laura Vinué ◽

George A. Jacoby ◽

...

Keyword(s):

Escherichia Coli ◽

Bacterial Community ◽

Vibrio Parahaemolyticus ◽

Cold Shock ◽

Vibrio Vulnificus ◽

Wild Type ◽

Induced Expression ◽

Content Type ◽

E Coli ◽

Dna Damaging Agents

ABSTRACT qnr genes are found in aquatic bacteria and were present in the bacterial community before the introduction of synthetic quinolones. Their natural functions are unknown. We evaluated expression of chromosomal qnr in Vibrio species in response to environmental stresses and DNA-damaging agents. Subinhibitory concentrations of quinolones, but not other DNA-damaging agents, increased expression of chromosomal qnr by more than five times in Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio mytili. Cold shock also induced expression of qnr in V. parahaemolyticus, V. vulnificus, and V. mytili, as well as expression of qnrS1 in Escherichia coli. qnrS1 induction by cold shock was not altered in ΔihfA or ΔihfB mutants or in a strain overexpressing dnaA, all of which otherwise directly modulate qnrS1 induction by ciprofloxacin. In contrast, the level of qnrS1 induction by cold shock was reduced in a ΔcspA mutant in the cold shock regulon compared to the wild type. In conclusion, cold shock and quinolones induce expression of chromosomal qnr in Vibrio species and of the related qnrS1 gene in E. coli.

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Occurrence of Potentially Human-Pathogenic Escherichia coli O103 in Norwegian Sheep

Applied and Environmental Microbiology ◽

10.1128/aem.01825-13 ◽

2013 ◽

Vol 79 (23) ◽

pp. 7502-7509 ◽

Cited By ~ 10

Author(s):

Camilla Sekse ◽

Marianne Sunde ◽

Petter Hopp ◽

Torkjel Bruheim ◽

Kofitsyo Sewornu Cudjoe ◽

...

Keyword(s):

Escherichia Coli ◽

Human Pathogens ◽

Outbreak Strain ◽

Banding Patterns ◽

Sheep Population ◽

Content Type ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

Uremic Syndrome ◽

Low Prevalence

ABSTRACTThe investigation of an outbreak of hemorrhagic-uremic syndrome in Norway in 2006 indicated that the outbreak strainEscherichia coliO103:H25 could originate from sheep. A national survey of the Norwegian sheep population was performed, with the aim of identifying and describing a possible reservoir of potentially human-pathogenicE. coliO103, in particular of the H types 2 and 25. The investigation of fecal samples from 585 sheep flocks resulted in 1,222E. coliO103 isolates that were analyzed for the presence ofeaeandstxgenes, while a subset of 369 isolates was further examined for flagellar antigens (H typing),stxsubtypes,bfpA,astA, and molecular typing by pulsed-field gel electrophoresis (PFGE). The total ovineE. coliO103 serogroup was genetically diverse by numbers of H types, virulotypes, and PFGE banding patterns identified, although a tendency of clustering toward serotypes was seen. The flocks positive for potentially human-pathogenicE. coliO103 were geographically widely distributed, and no association could be found with county or geographical region. The survey showed thateae-negative,stx-negativeE. coliO103, probably nonpathogenic to humans, is very common in sheep, with 27.5% of flocks positive. Moreover, the study documented a low prevalence (0.7%) of potentially human-pathogenic Shiga toxin-producingE. coliO103:H2, while STEC O103:H25 was not detected. However, 3.1% and 5.8% of the flocks were positive for enteropathogenicE. coliO103 belonging to H types 2 and 25, respectively. These isolates are of concern as potential human pathogens by themselves but more importantly as possible precursors for human-pathogenic STEC.

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Inactivation of Escherichia coli by Polychromatic Simulated Sunlight: Evidence for and Implications of a Fenton Mechanism Involving Iron, Hydrogen Peroxide, and Superoxide

Applied and Environmental Microbiology ◽

10.1128/aem.02419-13 ◽

2013 ◽

Vol 80 (3) ◽

pp. 935-942 ◽

Cited By ~ 17

Author(s):

Michael B. Fisher ◽

Kara L. Nelson

Keyword(s):

Escherichia Coli ◽

Hydrogen Peroxide ◽

Enteric Bacteria ◽

Growth Conditions ◽

Simulated Sunlight ◽

Wild Type ◽

Intracellular Iron ◽

Content Type ◽

E Coli ◽

Degree Of Sensitization

ABSTRACTSunlight inactivation ofEscherichia colihas previously been shown to accelerate in the presence of oxygen, exogenously added hydrogen peroxide, and bioavailable forms of exogenously added iron. In this study, mutants unable to effectively scavenge hydrogen peroxide or superoxide were found to be more sensitive to polychromatic simulated sunlight (without UVB wavelengths) than wild-type cells, while wild-type cells grown under low-iron conditions were less sensitive than cells grown in the presence of abundant iron. Furthermore, prior exposure to simulated sunlight was found to sensitize cells to subsequent hydrogen peroxide exposure in the dark, but this effect was attenuated for cells grown with low iron. Mutants deficient in recombination DNA repair were sensitized to simulated sunlight (without UVB wavelengths), but growth in the presence of iron chelators reduced the degree of sensitization conferred by this mutation. These findings support the hypothesis that hydrogen peroxide, superoxide, and intracellular iron all participate in the photoinactivation ofE. coliand further suggest that the inactivation rate of enteric bacteria in the environment may be strongly dependent on iron availability and growth conditions.

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Quantitative Microbial Risk Assessment for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in Leafy Green Vegetables Consumed at Salad Bars

Journal of Food Protection ◽

10.4315/0362-028x-73.2.274 ◽

2010 ◽

Vol 73 (2) ◽

pp. 274-285 ◽

Cited By ~ 64

Author(s):

E. FRANZ ◽

S. O. TROMP ◽

H. RIJGERSBERG ◽

H. J. van der FELS-KLERX

Keyword(s):

Public Health ◽

Escherichia Coli ◽

Risk Assessment ◽

Monte Carlo ◽

Escherichia Coli O157 ◽

Quantitative Microbial Risk Assessment ◽

Microbial Risk Assessment ◽

Microbial Risk ◽

The Public ◽

E Coli

Fresh vegetables are increasingly recognized as a source of foodborne outbreaks in many parts of the world. The purpose of this study was to conduct a quantitative microbial risk assessment for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes infection from consumption of leafy green vegetables in salad from salad bars in The Netherlands. Pathogen growth was modeled in Aladin (Agro Logistics Analysis and Design Instrument) using time-temperature profiles in the chilled supply chain and one particular restaurant with a salad bar. A second-order Monte Carlo risk assessment model was constructed (using @Risk) to estimate the public health effects. The temperature in the studied cold chain was well controlled below 5°C. Growth of E. coli O157:H7 and Salmonella was minimal (17 and 15%, respectively). Growth of L. monocytogenes was considerably greater (194%). Based on first-order Monte Carlo simulations, the average number of cases per year in The Netherlands associated the consumption leafy greens in salads from salad bars was 166, 187, and 0.3 for E. coli O157:H7, Salmonella, and L. monocytogenes, respectively. The ranges of the average number of annual cases as estimated by second-order Monte Carlo simulation (with prevalence and number of visitors as uncertain variables) were 42 to 551 for E. coli O157:H7, 81 to 281 for Salmonella, and 0.1 to 0.9 for L. monocytogenes. This study included an integration of modeling pathogen growth in the supply chain of fresh leafy vegetables destined for restaurant salad bars using software designed to model and design logistics and modeling the public health effects using probabilistic risk assessment software.

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Adjacent Terrestrial Landscapes Impact the Biogeographical Pattern of Soil Escherichia coli Strains in Produce Fields by Modifying the Importance of Environmental Selection and Dispersal

Applied and Environmental Microbiology ◽

10.1128/aem.02516-20 ◽

2021 ◽

Vol 87 (6) ◽

Author(s):

Jingqiu Liao ◽

Peter Bergholz ◽

Martin Wiedmann

Keyword(s):

Public Health ◽

Escherichia Coli ◽

Land Use ◽

Enteric Bacteria ◽

Content Type ◽

E Coli ◽

Biogeographic Pattern ◽

Environmental Selection ◽

Forest Sites ◽

Land Use Types

ABSTRACT High-quality habitats for wildlife (e.g., forest) provide essential ecosystem services while increasing species diversity and habitat connectivity. Unfortunately, the presence of such habitats adjacent to produce fields may increase risk for contamination of fruits and vegetables by enteric bacteria, including Escherichia coli. E. coli survives in extrahost environments (e.g., soil) and could be dispersed across landscapes by wildlife. Understanding how terrestrial landscapes impact the distribution of soil E. coli strains is of importance in assessing the contamination risk of agricultural products. Here, using multilocus sequence typing, we characterized 938 E. coli soil isolates collected from two watersheds with different landscape patterns in New York State, USA, and compared the distribution of E. coli and the influence that environmental selection and dispersal have on the distribution between these two watersheds. Results showed that for the watershed with widespread produce fields, sparse forests, and limited interaction between the two land use types, E. coli composition was significantly different between produce field sites and forest sites; this distribution appears to be shaped by relatively strong environmental selection, likely from soil phosphorus, and slight dispersal limitation. For the watershed with more forested areas and stronger interaction between produce field sites and forest sites, E. coli composition between these two land use types was relatively homogeneous; this distribution appeared to be a consequence of wildlife-driven dispersal, inferred by competing models. Collectively, our results suggest that terrestrial landscape attributes could impact the biogeographic pattern of enteric bacteria by adjusting the importance of environmental selection and dispersal. IMPORTANCE Understanding the ecology of enteric bacteria in extrahost environments is important for the development and implementation of strategies to minimize preharvest contamination of produce with enteric pathogens. Our findings suggest that watershed landscape is an important factor influencing the importance of ecological drivers and dispersal patterns of E. coli. Agricultural areas in such watersheds may have a higher risk of produce contamination due to fewer environmental constraints and higher potential of dispersal of enteric bacteria between locations. Thus, there is a perceived trade-off between priorities of environmental conservation and public health in on-farm food safety, with limited ecological data supporting or refuting the role of wildlife in dispersing pathogens under normal operating conditions. By combining field sampling and spatial modeling, we explored ecological principles underlying the biogeographic pattern of enteric bacteria at the regional level, which can benefit agricultural, environmental, and public health scientists who aim to reduce the risk of food contamination by enteric bacteria while minimizing negative impacts on wildlife habitats.

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Survival of Escherichia coli in Food at Hot-Holding Temperatures

Journal of Food Protection ◽

10.4315/0362-028x-49.7.496 ◽

1986 ◽

Vol 49 (7) ◽

pp. 496-499 ◽

Cited By ~ 4

Author(s):

CALEB A. MAKUKUTU ◽

RUFUS K. GUTHRIE

Keyword(s):

Public Health ◽

Escherichia Coli ◽

Analysis Of Variance ◽

Population Increase ◽

Food Type ◽

The Public ◽

E Coli ◽

Public Health Significance ◽

Health Significance ◽

Holding Temperature

Foods usually served hot were held at various hot-holding temperatures [40°C (104°F) - 60°C (140°F] and were contaminated with fecal Escherichia coli. The contaminated hot foods were held for 1 h at each of the hot-holding temperatures during which the survival of the pathogen in each food type was evaluated. Results showed that E. coli survived hot-holding temperatures in each food type for the whole period of evaluation. A population increase occurred with time at temperatures below 50°C (122°F), while at and above this temperature there was a decrease in population with increasing time in each food type. A two-way analysis of variance using relative rates of increase or decrease (± b) showed food type to be unimportant for survival of the bacteria. A three-way analysis of variance of the same results using mean log CFU/g food showed holding temperature, food type, holding time, and the interactions of temperature and food type; and temperature and time to be significantly important for survival of the bacteria. The public health significance of these findings are discussed.

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Acute Limonene Toxicity in Escherichia coli Is Caused by Limonene Hydroperoxide and Alleviated by a Point Mutation in Alkyl Hydroperoxidase AhpC

Applied and Environmental Microbiology ◽

10.1128/aem.01102-15 ◽

2015 ◽

Vol 81 (14) ◽

pp. 4690-4696 ◽

Cited By ~ 40

Author(s):

Victor Chubukov ◽

Florence Mingardon ◽

Wendy Schackwitz ◽

Edward E. K. Baidoo ◽

Jorge Alonso-Gutierrez ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Properties ◽

Wild Type ◽

Food Preservative ◽

Citrus Peel ◽

Content Type ◽

E Coli ◽

The Common ◽

Alkyl Hydroperoxidase ◽

Peel Oil

ABSTRACTLimonene, a major component of citrus peel oil, has a number of applications related to microbiology. The antimicrobial properties of limonene make it a popular disinfectant and food preservative, while its potential as a biofuel component has made it the target of renewable production efforts through microbial metabolic engineering. For both applications, an understanding of microbial sensitivity or tolerance to limonene is crucial, but the mechanism of limonene toxicity remains enigmatic. In this study, we characterized a limonene-tolerant strain ofEscherichia coliand found a mutation inahpC, encoding alkyl hydroperoxidase, which alleviated limonene toxicity. We show that the acute toxicity previously attributed to limonene is largely due to the common oxidation product limonene hydroperoxide, which forms spontaneously in aerobic environments. The mutant AhpC protein with an L-to-Q change at position 177 (AhpCL177Q) was able to alleviate this toxicity by reducing the hydroperoxide to a more benign compound. We show that the degree of limonene toxicity is a function of its oxidation level and that nonoxidized limonene has relatively little toxicity to wild-typeE. colicells. Our results have implications for both the renewable production of limonene and the applications of limonene as an antimicrobial.

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A survey of the microbiological quality of private water supplies in England

Epidemiology and Infection ◽

10.1017/s0950268899003970 ◽

2000 ◽

Vol 124 (3) ◽

pp. 417-425 ◽

Cited By ~ 22

Author(s):

M. RUTTER ◽

G. L. NICHOLS ◽

A. SWAN ◽

J. DE LOUVOIS

Keyword(s):

Public Health ◽

Escherichia Coli ◽

Water Quality ◽

Uv Light ◽

Microbiological Quality ◽

Light Treatment ◽

Water Supplies ◽

The Public ◽

E Coli

Results from statutory testing of private water supplies in nine Public Health Laboratories in England were compiled, and the effects of supply class, source, treatment and location on water quality were examined. A total of 6551 samples from 2911 supplies was examined, over a 2-year period, of which 1342 (21%) samples, and 949 (33%) supplies on at least one occasion, failed current regulations for Escherichia coli. Total coliforms, including E. coli, were detected in 1751 (27%) samples from 1215 (42%) supplies. The percentage of samples positive for E. coli was highest in summer and autumn, and lowest in winter. Samples taken from larger supplies and from boreholes were less frequently contaminated than those from other sources. Chlorination, filtration or UV light treatment improved the bacteriological quality of supplies, but still resulted in a low level of compliance with the regulations. The public health implications of the study are discussed.

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Indole Production Promotes Escherichia coli Mixed-Culture Growth with Pseudomonas aeruginosa by Inhibiting Quorum Signaling

Applied and Environmental Microbiology ◽

10.1128/aem.06396-11 ◽

2011 ◽

Vol 78 (2) ◽

pp. 411-419 ◽

Cited By ~ 74

Author(s):

Weihua Chu ◽

Tesfalem R. Zere ◽

Mary M. Weber ◽

Thomas K. Wood ◽

Marvin Whiteley ◽

...

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Mixed Culture ◽

Receptor Gene ◽

Enteric Bacteria ◽

Wild Type ◽

Content Type ◽

E Coli ◽

Culture Growth ◽

Indole Production

ABSTRACTIndole production byEscherichia coli, discovered in the early 20th century, has been used as a diagnostic marker for distinguishingE. colifrom other enteric bacteria. By using transcriptional profiling and competition studies with defined mutants, we show that cyclic AMP (cAMP)-regulated indole formation is a major factor that enablesE. coligrowth in mixed biofilm and planktonic populations withPseudomonas aeruginosa. Mutants deficient in cAMP production (cyaA) or the cAMP receptor gene (crp), as well as indole production (tnaA), were not competitive in coculture withP. aeruginosabut could be restored to wild-type competitiveness by supplementation with a physiologically relevant indole concentration.E. colisdiAmutants, which lacked the receptor for both indole andN-acyl-homoserine lactones (AHLs), showed no change in competitive fitness, suggesting that indole acted directly onP. aeruginosa. AnE. colitnaAmutant strain regained wild-type competiveness if grown withP. aeruginosaAHL synthase (rhlIandrhlI lasI) mutants. In contrast to the wild type,P. aeruginosaAHL synthase mutants were unable to degrade indole. Indole produced during mixed-culture growth inhibited pyocyanin production and other AHL-regulated virulence factors inP. aeruginosa. Mixed-culture growth withP. aeruginosastimulated indole formation inE. colicpdA, which is unable to regulate cAMP levels, suggesting the potential for mixed-culture gene activation via cAMP. These findings illustrate how indole, an early described feature ofE. colicentral metabolism, can play a significant role in mixed-culture survival by inhibiting quorum-regulated competition factors inP. aeruginosa.

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