Category Archives: Antibiotic Resistance

Research -Antibiotic-free poultry meat less likely to harbor multidrug-resistant Salmonella

CIDRAP Campylobacter kswfoodworld

An analysis by researchers in Pennsylvania found that meat from conventionally raised poultry harbored nearly twice as much multidrug-resistant Salmonella as meat from antibiotic-free poultry, according to a study reported today at IDWeek 2019.

The findings come from a study conducted by scientists with the Pennsylvania Department of Health, Penn State College of Medicine, and the Food and Drug Administration (FDA) that examined non-typhoidal Salmonella cultures from nearly 3,500 samples of chicken and turkey bought from randomly selected stores in Pennsylvania from 2008 through 2017. Analysis of the Salmonella cultures found that 55% of those from conventionally raised poultry meat were resistant to three or more antibiotic classes, compared with 28% of the cultures from the antibiotic-free poultry meat.

Salmonella is a leading cause of foodborne illness, affecting more than 1.2 million Americans each year. While most cases are self-limiting, some salmonellosis cases require antibiotics and hospitalization. Drug-resistant Salmonella is harder to treat and can cause more severe and sometimes deadly infections.

Research – Antibiotic resistant phenotypes of Staphylococcus aureus isolated from fresh and fermented milk in parts of Nasarawa State, Nigeria

Academic Journals


This work was aimed at determining the occurrence and antibiogram of Staphylococcus aureusisolated from fresh and fermented milk samples in parts of Nasarawa State, Nigeria. A total of 180 samples comprising of fresh raw milk, bulk milk, nono, and kindirmo were collected over a period of 6 months (May to October, 2017). Standard microbiological procedures were employed in the isolation, identification, characterisation, and determination of the antibiogram of S. aureus from the milk samples. Characterisation of the S. aureus isolates was by morphological, biochemical characteristics using conventional methods, Microgen® STAPH-ID kits. Confirmed isolates were tested for susceptibility or resistance to a panel of 11 commonly used antibiotics using the agar disc diffusion technique. Out of the 180 milk samples examined, 9 S. aureus were isolated giving a prevalence of 5.0%. The occurrence of S. aureus was higher in nono (12.1%) and kindirmo (10.6%) than in fresh raw milk (5.9%). The high occurrence of S. aureus in nono disproved the assertion that fermented foods are not good media for the survival and growth of S. aureus. The antibiotic susceptibility profile of the S. aureus isolates indicated all of the nine isolates were completely resistant to cefoxitin, ampicillin, and amoxicillin/clavulanic acid. The isolates were moderately resistant to erythromycin (22.2%), sulphamethoxazole/trimethoprim (22.2%), and tetracycline (44.4%). Five antibiotic resistance patterns were recorded among the isolates. All of the isolates had a multiple antibiotics resistance (MAR) index of 0.3 and above, an indication of possible antibiotic misuse in the areas studied.

Research – Antimicrobial resistance profile of Escherichia coli isolates recovered from diarrheic patients at Selam Health Center, Addis Ababa, Ethiopia

Academic Journals


Antimicrobials have been playing an important role in preventing illness and death associated with infections due to bacteria. However, the emergence and spread of resistance by pathogens have decreased the effectiveness of the commonly prescribed antimicrobials. Intestinal Escherichia coli are among bacterial pathogens that are endowed with such resistance traits because they are important source and reservoir of genes that encode antimicrobial resistance. To determine the antimicrobial resistance profile of fecal isolates of E. coli from diarrheic patients. Stool samples were collected consecutively from 100 individuals who visited Selam Health Center during the study period, April to June 2018. Samples were collected and transported under sterile condition to the National Clinical Bacteriology and Mycology reference Laboratory, Ethiopian Public Health Institute. The samples were streaked on MacConkey agar and incubated overnight at 37°C. E. coli isolates were further confirmed using conventional biochemical tests. Antimicrobial susceptibility status was determined using the disk diffusion method on Mueller Hinton agar as recommended by the Clinical Laboratory Standard Institute. The raw data was compiled and entered to spreadsheet and analysis was done using SPSS Version 20 with p-value ≤0.05 considered statistically significant. Out of the 100 patients, 43 were female and the rest were male. Confirmed E. coli were isolated from 73 individuals. Antimicrobial susceptibility testing showed that E. coli isolated in this study were highly resistant to trimethoprim-sulfamethoxazole 49 (67.1%) and amoxicillin-clavulanic acid 47(64.4 %). No isolates showed resistance to gentamicin and tobramicin.  Of all the isolates, 11(15.1%) were multidrug resistant. No association was observed between antimicrobial resistance status and sex of individuals included in this study. However, there was an association between age and resistance patterns. Resistance to commonly prescribed antibiotics among E. coli isolated in this study was high and a considerable proportions of the strains were multidrug resistant. This is an indication for an alarming rate of resistance of intestinal E. coli to first line antimicrobials. To reduce the problem, regular monitoring and education for the community are very important.

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.