Category Archives: Antibiotic Resistance

Research – Global Emergence of Colistin-Resistant Escherichia coli in Food Chains and Associated Food Safety Implications: A Review

Journal of Food Protection


Antimicrobial resistance in bacteria represents one of the most important challenges for public health worldwide. Human infections from antimicrobial-resistant bacteria can be transmitted from person to person, via the environment (especially in the hospital environment), or via handling or eating contaminated foods. Colistin is well known as a last-resort antibiotic for the treatment of human infections; a recent study performed in the People’s Republic of China has revealed that colistin resistance is also conferred by the plasmid-mediated mcr-1 gene in Escherichia coli. After that discovery, further plasmid-mediated, colistin resistance genes have been detected. However, to date, only reports on E. coli carrying the mcr-1 gene (E. coli mcr-1+) in foodstuff are available. E. coli mcr-1+ has been isolated from food of animal origin and vegetables; this discovery has opened a debate among food safety experts. This review aims to provide a critical overview of the currently available scientific literature on the presence of the plasmid-mediated, colistin resistance gene E. coli mcr-1 in foodstuffs, focusing on the main implications and future perspectives for food safety.

  • Antimicrobial resistance in the food chain: a One Health perspective.

  • Escherichia coli carries the mcr-1 gene in food-producing animals.

  • Escherichia coli carrying the mcr-1 gene in food from animals and vegetables is significant.

Research -Slow growth determines nonheritable antibiotic resistance in Salmonella enterica

Science Mag

kswfoodworld Salmonella

Image CDC

Slow growth for bacterial persistence

Even bacteria that do not carry mutations or genes that confer resistance to specific antibiotics can survive antibiotic treatment, a phenomenon known as persistence (see the Focus by Kaldalu and Tenson). Several models have been proposed to account for bacterial persistence, including the activation of toxins in toxin-antitoxin modules, the production of the alarmone guanosine (penta) tetraphosphate [(p)ppGpp], and a reduction in intracellular adenosine triphosphate (ATP) abundance. Pontes and Groisman demonstrated that Salmonella exhibited persistence even in the absence of toxin-antitoxin modules or (p)ppGpp production and under conditions that increased intracellular ATP. These and additional findings show that slow growth alone is sufficient for persistence and may contribute to the difficulty in treating some bacterial infections.


Bacteria can withstand killing by bactericidal antibiotics through phenotypic changes mediated by their preexisting genetic repertoire. These changes can be exhibited transiently by a large fraction of the bacterial population, giving rise to tolerance, or displayed by a small subpopulation, giving rise to persistence. Apart from undermining the use of antibiotics, tolerant and persistent bacteria foster the emergence of antibiotic-resistant mutants. Persister formation has been attributed to alterations in the abundance of particular proteins, metabolites, and signaling molecules, including toxin-antitoxin modules, adenosine triphosphate, and guanosine (penta) tetraphosphate, respectively. Here, we report that persistent bacteria form as a result of slow growth alone, despite opposite changes in the abundance of such proteins, metabolites, and signaling molecules. Our findings argue that transitory disturbances to core activities, which are often linked to cell growth, promote a persister state regardless of the underlying physiological process responsible for the change in growth.

Research – New compound which kills antibiotic-resistant superbugs discovered

Science Daily

A new compound which visualises and kills antibiotic resistant superbugs has been discovered by scientists at the University of Sheffield and Rutherford Appleton Laboratory (RAL).

The team, led by Professor Jim Thomas, from the University of Sheffield’s Department of Chemistry, is testing new compounds developed by his PhD student Kirsty Smitten on antibiotic resistant gram-negative bacteria, including pathogenic E. coli.

Gram-negative bacteria strains can cause infections including pneumonia, urinary tract infections and bloodstream infections. They are difficult to treat as the cell wall of the bacteria prevents drugs from getting into the microbe.

Antimicrobial resistance is already responsible for 25,000 deaths in the EU each year, and unless this rapidly emerging threat is addressed, it’s estimated by 2050 more than 10 million people could die every year due to antibiotic resistant infections.

Doctors have not had a new treatment for gram-negative bacteria in the last 50 years, and no potential drugs have entered clinical trials since 2010.

The new drug compound has a range of exciting opportunities. As Professor Jim Thomas explains: “As the compound is luminescent it glows when exposed to light. This means the uptake and effect on bacteria can be followed by the advanced microscope techniques available at RAL.

Research – Relationship of Sanitizers, Disinfectants, and Cleaning Agents with Antimicrobial Resistance

Journal of Food Protection

Sanitizers, disinfectants, and cleaning agents are vital to food hygiene assurance and are a major public health protection measure. Limiting microbial antibiotic resistance is also a global public health priority. Although many factors contribute to the rise in antimicrobial resistance in bacteria infecting humans, antibiotic use in both human clinical settings and for food-producing animals are primary contributors. Some concerns have been raised about the possibility of coselection between food hygiene chemicals and reduced antimicrobial susceptibility. This article reviews available evidence from individual studies purporting to demonstrate a possible risk of antimicrobial resistance development, following biocide usage. Furthermore, the conclusions of several key expert reports and meta-analysis publications were assessed for supportive evidence of a relationship between biocide usage in food production and resistance development. Although many studies report on the isolation of antimicrobial-resistant bacterial strains in food, evidence is lacking on the attribution of this resistance to biocide usage. Also, although a theoretical risk of causality exists, many of the studies performed to demonstrate this are in vitro studies using laboratory-grown or -trained bacterial isolates, challenged with sublethal (below the recommended food industry) disinfectant or sanitizing agent concentrations. The proper use of, and adherence to biocide manufacturer’s instruction for use, and the avoidance of biocide active agent dilution (e.g., through biofilm presence) must be ensured in food production environments. It is recommended that in situ studies should be performed to further assess causality, ensured a clear differentiation between interpretation of stable antimicrobial resistance and phenotypic adaptation. Furthermore, authorization of new biocidal active substances should take a scientific and risk-based approach regarding the potential for driving microbial resistance.

  • Sanitizers and disinfectants (biocides) are essential for food safety assurance.

  • Concerns have been raised about theoretical risk of biocide-induced antimicrobial resistance.

  • In vitro studies provide weak causal evidence to attribute antimicrobial resistance to biocide usage.

  • GMPs, proper biocide usage, and avoidance of biofilms mitigate risk of antimicrobial resistance.

Research – Chicken superbug CAN’T be treated with antibiotics: Warning as common bacteria found in half of supermarket poultry turns drug resistant

Daily Mail


Image CDC

  • Campylobacter is found at low levels on half of chickens sold by major stores 
  • The bug is responsible for an estimated 500,000 cases of illness in the UK
  • More than nine per cent of one strain is resistant to three types of antibiotic 
  • Farmer using antibiotics to treat animals have raised levels of resistance 


Research – Increased prevalence of Escherichia coli strains from food carrying blaNDM and mcr-1-bearing plasmids that structurally resemble those of clinical strains, China, 2015 to 2017


Antimicrobial resistance poses an increasing risk to human and animal health worldwide. In particular, carbapenem resistance mediated by serine β-lactamases and metallo-β-lactamases (MBLs), such as the OXA enzymes produced by  and  carbapenemase (KPC-1) and New Delhi metallo-β-lactamase (NDM-1) produced by Enterobacteriaceae, is associated with a high mortality rate among hospitalised patients [1,2]. NDM-1, a type of Ambler class B metallo-β-lactamases (MBLs), exhibits high hydrolytic activity against almost all known β-lactam antimicrobials (except aztreonam), including the last-line carbapenems [3,4]. It was first found to be produced by  and  strains isolated from a Swedish patient of Indian origin who was admitted to hospital in New Delhi, India [5]. Thereafter, the   gene disseminated in various countries and regions such as China, the Middle East, South East Asia and Europe [4]. This multidrug resistance gene, which may be located on either plasmids or chromosome [3,6,7], leaves few therapeutic options for infected patients. In China, Ho et al. reported the first isolation of  -positive  from a 1-year-old infant and its mother in 2011 [8]. NDM-1-producing Enterobacteriaceae have since disseminated to various provinces in China, with the majority of such strains isolated from stool samples [9]. However, reports of isolation of carbapenem-resistant Enterobacteriaceae (CRE) from food samples remain scarce around the world.

Research – Vibrio spp. from Yesso scallop (Patinopecten yessoensis) demonstrating virulence properties and antimicrobial resistance

Wiley Online Library


We report the prevalence and characterization of Vibrio spp. isolated from marketed Yesso scallop (Patinopecten yessoensis) in Korea. A total of 30 isolates including, V. parahaemolyticus (n = 2), V. alginolyticus (n = 9), V. fluvialis (n = 7), V. diabolicus (n = 7), V. anguillarum (n = 4) and V. aestuarianus (n = 1) were isolated and identified. The phenotypic pathogenicity tests demonstrated that, 18 (60%), 21 (70%), 18 (60%), 7 (23%), 22 (73%), 21 (70%), 9 (30%), and 11 (33%) of the isolates were positive for DNase, protease, gelatinase, lipase, phospho‐lipase, amylase, slime production, and haemolysis, respectively. PCR assays revealed the prevalence of toxR, tlh, VAC, vfh, hupO, and VPI genes among the isolates with varying combinations. A close genetic affinity among V. alginolyticus and V. diabolicus strains was observed. Also the virulence genes specific to one Vibrio species were detected among other species as well. In addition, 29/30 (97%) isolates were multidrug resistant, while higher resistance rates were shown for ampicillin, colistin, vancomycin, and cephalothin. The results imply that the scallops in Korean markets harbor Vibrio spp., which are potentially virulent and multidrug resistant, thus their public health implications should not be underrated.

Practical applications

For many decades, vibrios are known for its importance in seafoodborne illnesses. Yesso scallop is the most popular and extensively cultured scallop variety in Korea. Therefore, we sought to assess the marketed fresh Yesso scallops for the prevalence and molecular characterization of Vibrio species. A total of 30 strains were isolated and identified by a series of biochemical tests, subsequent gyrB gene sequencing and phylogenetic analyses. Six Vibrio spp. were identified with V. alginolyticus as the most prevalent. Interestingly, V. alginolyticus was genetically similar to V. diabolicus. Besides, the virulence genes specific to V. alginolyticus and V. parahaemolyticus were observed in other species as well. It suggests that the detection of the species‐specific genes does not ensure the correct identification of pathogenic vibrios. Further, the occurrence of V. parahaemolyticus‐specific virulence genes in other Vibrio spp. potentially complicates the correct tracking of V. parahaemolyticus infections. In addition, 73% of these Vibrio spp. isolates showed multiple antibiotic resistance (MAR) indices higher than 0.2, which signifies their high risk of infection. Collectively, these results provide important evidence that not only the well‐known pathogenic vibrios like V. parahaemolyticus, but also other Vibrio spp. can act alike because of their similar characteristics.