Category Archives: Antimicrobials

Research – Eugenol as an antimicrobial wash treatment reduces Campylobacter jejuni in postharvest poultry

Wiley Online

Abstract

The efficacy of the natural plant‐derived compound, eugenol (EG), as an antimicrobial wash treatment to reduce Campylobacter jejuni in postharvest poultry was investigated. The antimicrobial efficacy of EG was studied as a suspension, emulsion, or nanoemulsion treatment (two trials each). In each trial, chicken skin samples were inoculated with C. jejuni (∼7.2 Log CFU/sample), washed with treatments (0, 0.125, 0.25, 0.5, 1, or 2% EG corresponds to 0, 7.61, 15.22, 30.45, 60.90, or 121.8 mM, respectively) for 1 min, drip dried for 2 min, and then processed at 0, 8, and 24 hr of refrigerated storage (n = 5 samples/treatment/time point). All doses of the EG suspension consistently reduced C. jejuni counts with the greatest reduction (>2.0 Log CFU/sample) for the 2% dose when compared with controls (p < .05). EG emulsions or nanoemulsions did not provide any additional reduction in C. jejuni when compared to EG suspension. Our results suggest that EG could be an effective postharvest intervention strategy for reducing C. jejuni contamination on poultry products.

Practical Applications

Campylobacter jejuni, a leading cause of foodborne illness in humans, is strongly associated with the consumption of contaminated poultry products. Interventions reducing C. jejuni contamination in poultry would reduce the risk of subsequent human infections. In this study, the antimicrobial efficacy of eugenol was studied in three different delivery systems; suspension, emulsion, or nanoemulsion. Our results demonstrated that eugenol was effective in reducing C. jejuni counts on chicken skin and can be used as a potential strategy to reduce Campylobacter on poultry products.

Research – Antibacterial mechanism of Tetrapleura tetraptera extract against Escherichia coli and Staphylococcus aureus and its application in pork

Wiley Online

Abstract

The antibacterial activity and the mechanism of Tetrapleura tetraptera root extract against Escherichia coli and Staphylococcus aureus were investigated. The mechanism of action of T. tetraptera on tested bacterial species was predominantly characterized by the study of transmission electron microscopy, which revealed severe damage on the primary target which affected the cell integrity and cell membrane permeability. The loss of soluble proteins studied by bacterial protein sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis and the decreased adenosine triphosphate and DNA contents confirmed the leakage of cell wall. In addition, the studies revealed that the root extract of T. tetraptera could also disrupt the respiratory metabolism by inhibiting the bacteria through the Embden–Meyerhof–Parnas and the hexose monophosphate pathways. T. tetraptera extract possessed a high level of antimicrobial activity in pork, which significantly reduced total viable bacterial population. This study clearly indicates that the T. tetraptera could be a potential source of new antimicrobial agent which has proven effective activity against antibiotic‐resistant strains of pathogens.

Practical Applications

Tetrapleura tetraptera is a flowering plant native to Africa with a wide range of applicability in local cuisines and traditional medicine. The T. tetraptera root extract possesses high antimicrobial activity against both gram‐positive and gram‐negative bacteria. This study could contribute to the better understanding of antibacterial mechanism of T. tetraptera. As a natural food preservative, it has broad prospect to be utilized in the meat industry.

Research – Chemical composition and antimicrobial activity against food‐related microorganisms of different essential oils from Lebanon

Wiley Online

Abstract

Essential oils (EOs) have long been recognized for their medicinal properties. Application of EOs in food preservation has gained recent interest as natural alternatives to conventional chemicals. Even though the properties of EOs are extensively documented, their effect on several food‐related microorganisms is yet to be explored. In this study, six EOs were extracted by hydrodistillation and analyzed using GC/MS techniques, and then antimicrobial activity was tested against microorganisms of food interests through minimal inhibitory concentration (MIC) techniques. Both Coridothymus capitatus and Origanum syriacum EOs showed an antifungal activity (MIC ≤ 0.625 μL/mL). Interestingly all foodborne pathogens tested were sensitive to Ccapitatus EO and two of them, Staphylococcus aureus and Listeria monocytogenes, to Osyriacum EO (MIC ≤ 1.25 μL/mL) while the beneficial food‐related bacteria (Lactobacillus sp.) were not affected (MIC ± 10 μL/mL). Finally, Cinnamomum zeylanicum EO showed a broader antimicrobial activity on all microorganisms analyzed.

Practical Applications

Essential oils from Lebanese plants could be used to selectively control foodborne pathogens, including fungi and bacteria. These essential oils could represents an alternative to conventional anti microbials as they did not affect benefiacial food‐related bacteria.

Research -Anti‐listeria activity and shelf life extension effects of Lactobacillus along with garlic extract in ground beef

Wiley Online

Abstract

The current study investigates the effect of Lactobacillus reuteri and Lactobacillus plantarum combined with water extract of garlic on microbial growth, chemical changes, and sensory attributes in ground beef samples at refrigeration condition (+4°C) up to 12 days of storage. in vitro study revealed that garlic extract combined with L. reuteri or L. plantarum caused 2.13 and 2.57 log reduction in the Listeria monocytogenes count, respectively. Combination of L. plantarum and 1% garlic extract significantly (p < .05) reduced aerobic mesophilic bacteria (1.64 log cycle) and L. monocytogenes (1.44 log cycle) counts in ground beef. Lipid oxidation was also significantly (p < .05) lower in samples treated with L. plantarum plus garlic extract (1%). Furthermore, higher sensory scores were received by samples treated with Lactobacillus plus garlic extract. In conclusion, the combination of L. plantarum and garlic extract was found to be suitable to use in ground beef by controlling the L. monocytogenes growth and increasing its shelf life.

Practical Applications

Garlic extract not only has an antimicrobial activity but also has a stimulatory effect on the Lactobacillus spp. growth. On the other hand, some Lactobacillus strains can inhibit pathogenic bacteria. Then, the combination of Lactobacillus and garlic extract may be used to produce new bio‐preserved and functional meat products. The current study indicated the potential of Lactobacillus combined with garlic extract to control microbial and chemical changes in ground beef. The combination of Lactobacillus plantarum and garlic extract significantly (p < .05) reduced Listeria monocytogenes counts and lipid oxidation rates and improved the sensory scores in ground beef.

Research – Assessing the Efficacy of Sodium Bisulfate and Organic Acid Treatments for Control of Salmonella Typhimurium in Rendered Chicken Fat Applied to Pet Foods

Journal of Food Protection

ABSTRACT

This study was conducted to evaluate the effects of sodium bisulfate (SBS), lactic acid (LA), phosphoric acid (PA), and combinations of organic acids with SBS on Salmonella in rendered chicken fat and in water. The MICs of the antimicrobials individually and in combination were determined. Efficacies of the antimicrobials against Salmonella were tested in both media. The MICs of SBS, LA, and PA were 0.5, 0.5, and 0.25%, respectively. At the given concentrations in the water phase, 0.5% SBS was more effective (P < 0.05; 2.7-log reduction) than LA and PA at 0 h. SBS and LA were more effective (P < 0.05) than PA with >4-log reductions at 2 h and complete kill at 6 h. After 24 h, each of the chemicals completely eliminated the Salmonella. However, because of low recovery in the fat phase, Salmonella was not detected after 12 h and all three chemicals effectively reduced (P < 0.05) Salmonella at 6 h compared with the control. When combinations were used in the water phase, SBS plus butyric acid decreased (P < 0.05) Salmonella by >5.5 log CFU/mL after 12 h. The SBS+LA combinations were effective (P < 0.05) after 2 h. The combinations of SBS+PA resulted in ∼3.5-log reductions in Salmonella (P < 0.05) after 6 h. In the fat phase, except for the SBS+PA combination, Salmonella reduction was not different from that for the positive control. When SBS was combined with organic acids, Salmonella inhibition was achieved at a lower SBS concentration, indicating a possibly synergistic effect of these chemicals. These results suggest that inclusion of SBS or LA at 0.5% individually or a combination of SBS with organic acids could reduce Salmonella in rendered chicken fat contaminated by residual water encountered during storage and transport.

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

Academic Journals

Abstract

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

Abstract

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 – Perception Problems for Multidrug-Resistant Organisms

Contagion Live

We’ve all seen the statistics—each year in the United States, 2 million people will get an antibiotic-resistant infection and at least 23,000 will die as a result of them. Moreover, multidrug-resistant organisms (MDROs) represent an increasing threat to global health as it’s estimated that their mortality rates will exceed those of cancer by 2050. It’s easy to see such data and focus on how to cut down the rates or how to increase antimicrobial stewardship without thinking about the perceptions or emotional impact of these infections.

How do health care workers experience MDROs? What about patients? These types of questions are rarely discussed in infection prevention or antimicrobial resistance efforts but, nonetheless, play a critical role. A new study from a research team in Germany sought to truly understand how these perceptions affect efforts such as hand hygiene, disinfection, and isolation. We all too often focus on the isolation and rapid identification of patients with MDROs but rarely discuss the social and psychological implications of such infections.

Investigators used a socio-constructivist focus and a mixed-method approach to conduct the study, which was broken into sections that included discussions, peer-assisted objective-structured clinical examination, and constructive efforts like card surveys and papers. Topics included infectious diseases and microbiology, basic hygiene procedures, communication techniques, and special protective hazardous material equipment. The research team had 51 health care workers from 13 professions across 5 hospitals participate in this training and data collection. Overall, they found that there are significant barriers both in educating clinicians and then informing patients and family members, and also in handling emotional responses in patients diagnosed and isolated with an MDRO infection.

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

Journal of Food Protection

ABSTRACT

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.

HIGHLIGHTS
  • 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.

Abstract

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.