Breaking News
March 22, 2019 - Less invasive valve replacement can be safe and effective alternative for healthier patients
March 22, 2019 - Aphasia research reveals new, complex interactions between thought and language
March 22, 2019 - Artificial neural networks can predict how different areas in the brain respond to words
March 22, 2019 - Age-related changes to gut microbiome have adverse impact on vascular health, study shows
March 22, 2019 - Isolated seniors chat online to prevent cognitive decline
March 22, 2019 - Karyopharm Announces FDA Extension of Review Period for Selinexor New Drug Application
March 22, 2019 - Eruptive xanthomatosis
March 22, 2019 - Cause of vascular disease in kidney failure reversed in animal model
March 22, 2019 - Researchers discover possible new therapeutic strategy for pancreatic cancer
March 22, 2019 - Ebola spreads to second largest city in DRC
March 22, 2019 - Perivascular spaces contribute to worse cognitive health in older adults
March 22, 2019 - Adolescent daily users more likely to obtain electronic cigarettes from commercial sources
March 22, 2019 - FDA Approves Genentech’s Tecentriq in Combination With Chemotherapy for the Initial Treatment of Adults With Extensive-Stage Small Cell Lung Cancer
March 22, 2019 - Diabetes myths and facts: MedlinePlus Medical Encyclopedia
March 22, 2019 - TGen and ABL pursue global rollout of advanced TB test
March 22, 2019 - Traffic light labels influence people to choose healthier and more sustainable meals
March 22, 2019 - Alzheimer’s patients using antiepileptic drugs have twice the risk of pneumonia, study shows
March 22, 2019 - Skin diseases may be more prevalent than previously thought
March 22, 2019 - Overall rates of death from breast cancer are falling across the EU
March 22, 2019 - Novel plasmid could hold key to control of mosquito-borne illness
March 22, 2019 - Female Emergency Physicians Paid Less Than Males
March 22, 2019 - Estimated average glucose (eAG): MedlinePlus Medical Encyclopedia
March 22, 2019 - Experimental drug could be new option for type 2 diabetes
March 22, 2019 - Five Things To Know About The Electronic Health Records Mess
March 22, 2019 - TMJ disorders could be treated with tissue-engineered implants after successful animal study
March 22, 2019 - Team-based approach is key to successful care of pregnant women with heart failure
March 22, 2019 - Study identifies gene variant associated with accelerated cellular aging
March 21, 2019 - Salk scientists show how background noise from neurons can interrupt focused attention
March 21, 2019 - New class of drugs could help treat patients diagnosed with ovarian cancer
March 21, 2019 - Tecentriq Approved for Small Cell Lung Cancer
March 21, 2019 - Adipocyte glucocorticoid receptors play a role in developing steroid diabetes
March 21, 2019 - Climate change can affect nutrient content of crops, harming human health
March 21, 2019 - Podcast: KHN’s ‘What The Health’ Surprise! Fixing Surprise Medical Bills Is Harder Than it Looks
March 21, 2019 - Chemistry researchers patent new method for making anti-leukemia compounds
March 21, 2019 - UIC scientists identify hidden proteins in bacteria
March 21, 2019 - New Australian drug trial achieves remarkable results in patients with acute myeloid leukemia
March 21, 2019 - Females live longer when they have help raising offspring
March 21, 2019 - How did orthodontists sell orthodontics?
March 21, 2019 - In the Spotlight: From dietitian to physician assistant student
March 21, 2019 - The CRISPR Revolution: What You Need to Know
March 21, 2019 - FDA Chief Calls For Stricter Scrutiny Of Electronic Health Records
March 21, 2019 - Combined glucocorticoid and antioxidant therapy could benefit premature babies
March 21, 2019 - Low levels of certain eye proteins could serve as predictor for Alzheimer’s
March 21, 2019 - Post-traumatic holocaust survivors transmit negative views on aging to offspring
March 21, 2019 - City of Hope receives $7.5 million in grant awards to study cutaneous T cell lymphoma
March 21, 2019 - New video game-led training device helps stroke survivors regain arm mobility
March 21, 2019 - Compounds in coffee could slow prostate cancer growth
March 21, 2019 - New mobile DNA element in Wolbachia may contribute to improved disease control strategies
March 21, 2019 - Phase 2 Clinical Trial of Bermekimab Shows Potential New Standard of Care for Treatment of Hidradenitis Suppurativa, Including Significant Pain Reduction without Antibiotics
March 21, 2019 - More than one-third of patients risk major bleeding by doubling up on blood thinners
March 21, 2019 - A skeptical look at popular diets: Thumbs up for Mediterranean
March 21, 2019 - PTSD After Cardiac Arrest Predicts More Heart Trouble
March 21, 2019 - Role of immunological imprinting in elicitation of new antibodies
March 21, 2019 - Breast cancer relapse predictor tool may soon be a reality
March 21, 2019 - New computer program developed by TGen lights up cancer-causing genetic mutations
March 21, 2019 - FDA warns two breast implant makers for failure to comply with post-approval study requirements
March 21, 2019 - Butler Hospital receives COBRE grant to enhance research on neuropsychiatric illnesses
March 21, 2019 - Majority of osteoporosis clinical practice guidelines ignore patients’ voices
March 21, 2019 - Generic messages don’t help patients to lose weight
March 21, 2019 - Eisai and Imbrium Therapeutics Announce U.S. FDA Filing Acceptance of New Drug Application for Lemborexant for the Treatment of Insomnia
March 21, 2019 - Two-drug combos using popular calcium channel blocker show superiority in lowering BP
March 21, 2019 - Q BioMed and Mannin Research collaborate with McMaster University to develop GDF15 biomarker glaucoma diagnostic kit
March 21, 2019 - First-in-human pilot study shows positive results for ‘bacteria-phobic’ catheter
March 21, 2019 - Itamar Medical launches next-generation WatchPAT system for home sleep apnea testing
March 21, 2019 - Study estimates health and economic impacts of healthy food prescriptions
March 21, 2019 - Detecting fungal disease in crops with multispectral imaging system
March 21, 2019 - MIT announces creation of the Alana Down Syndrome Center
March 21, 2019 - Next-generation LVAD device clinically superior, safer for heart failure patients
March 21, 2019 - Allergan Announces FDA Approval of Avycaz (ceftazidime and avibactam) for Pediatric Patients
March 21, 2019 - Mutations in noncoding genes could play big role in regulating cancer, study finds
March 21, 2019 - A medical student’s thoughts on Match Day
March 21, 2019 - Are eggs good or bad for you?
March 21, 2019 - New analysis reveals precision oncology insights for colorectal cancer
March 21, 2019 - Pollutants appear to weaken immune system and increase pathogen virulence
March 21, 2019 - Researchers develop and validate scale for rating severity of mononucleosis
March 21, 2019 - Scientists identify generation of key immune response in mice on introducing solid food
March 21, 2019 - New nanomaterial could restore internal structure of damaged bones
March 21, 2019 - Selective destruction of prostate tumor as effective as complete prostate removal
March 21, 2019 - 2011 to 2015 Saw Increase in Psychiatric ED Visits for Youth
March 21, 2019 - Tapeworm drug targets common vulnerability in tumor cells
Common bacteria that cause foodborne diseases found to be resistant to antibiotics

Common bacteria that cause foodborne diseases found to be resistant to antibiotics

image_pdfDownload PDFimage_print

Brazil’s Ministry of Health received reports of 11,524 outbreaks of foodborne diseases between 2000 and 2015, with 219,909 individuals falling sick and 167 dying from the diseases in question. Bacteria caused most outbreaks of such illnesses, including diarrhea and gastroenteritis. The most frequent were Salmonella spp., with 31,700 cases diagnosed in the period (14.4% of the total), Staphylococcus aureus (7.4%), and Escherichia coli (6.1%).

According to a survey by the Ministry of Social Development, bacteria of the genus Salmonella were the etiological agents in 42.5% of the laboratory-confirmed foodborne disease outbreaks reported in Brazil between 1999 and 2009.

Whole-genome sequencing of the main bacteria that cause acute diarrhea is the research focus for a group at the University of São Paulo led by Juliana Pfrimer Falcão, a professor at the university’s Ribeirão Preto School of Pharmaceutical Sciences (FCFRP-USP).

In an article published in PLOS ONE, biomedical scientists Amanda Aparecida Seribelli and Fernanda Almeida, who belong to Falcão’s lab, describe how they sequenced and investigated the genomes of 90 strains of a specific serovar of Salmonella enterica known as S. Typhimurium (an abbreviation of Salmonella enterica subspecies serovar Typhimurium).

The 90 strains were isolated between 1983 and 2013 at Adolfo Lutz Institute in Ribeirão Preto (São Paulo State, Brazil) and Oswaldo Cruz Foundation (Fiocruz) in Rio de Janeiro. They provide a portrait of the epidemiology of salmonellosis in Brazil in the last 30 years, coming from all regions of the country and having been collected from patients with foodborne infections or from contaminated food such as poultry, pork, or lettuce and other vegetables.

“From humans, we received samples of blood, brain abscesses, and diarrheic feces,” Seribelli told.

When the action of antibiotics in each of the 90 strains was tested, it was discovered that the vast majority were resistant to different classes of antibiotics that are part of the arsenal of medicine. The study also identified 39 genes responsible for resistance to antibiotics.

Researchers affiliated with Fiocruz, São Paulo State University’s School of Agrarian and Veterinary Sciences (FCAV-UNESP) and Adolfo Lutz Institute participated in the study. The 90 strains of S. Typhimurium were sequenced at the United States Food and Drug Administration (FDA) during Almeida’s doctoral stay.

The comparative analysis of the genomes, transcriptomes, and phenotypes of S. Typhimurium strains isolated from humans and food in Brazil was supported by São Paulo Research Foundation – FAPESP, the FDA, and the Ministry of Education’s Office for Faculty Development (CAPES).

Salmonellosis

Salmonella comprises two species, S. bongori and S. enterica. The latter is the type species, with a large number of subspecies and serovars that cause more foodborne infections than any other species in Brazil and worldwide. The human and animal intestinal tract is the main natural reservoir for this pathogen, with poultry, pork and related food products serving as major transmission vectors.

The six subspecies of S. enterica are subdivided into 2,600 serovars. A serovar (short for serological variant) is a distinct variation within a species of bacteria or virus characterized by having the same number of specific surface antigens.

The most important subspecies of S. enterica from the epidemiological standpoint is S. enterica subspecies enterica, which causes the foodborne infection known as salmonellosis. The symptoms are diarrhea, fever, stomach cramps, and vomiting.

S. enterica subsp. enterica was the main cause of the 31,700 cases of salmonellosis reported in Brazil between 2000 and 2015. The most frequently isolated serovars of this subspecies are S. Typhimurium and S. Enteritidis.

S. Enteritidis is one of the leading salmonellosis-causing serovars. It first spread in a pandemic that started in Europe in the 1990s. S. Typhimurium was the most prevalent serovar before the pandemic and has continued to cause infections.

According to Almeida, all 90 strains analyzed in the study belonged to S. Typhimurium. Another researcher at FCFRP-USP (also working at the university’s Clinical, Toxicological and Bromatological Analysis Laboratory) is currently sequencing and analyzing samples containing the serovar S. Enteritidis.

Almeida took the 90 strains of S. Typhimurium to the US in 2015. “Their genomes were sequenced at the FDA’s Center for Food Safety and Applied Nutrition in Maryland under the supervision of researcher Marc W. Allard,” he said.

S. Typhimurium‘s genome contains 4.7 million base pairs. Brief reflection tells us that the study generated a mountain of data, more specifically 423 million bases corresponding to the sum of 90 genomes.

After his return to Ribeirão Preto, Almeida worked with Seribelli on a comparative analysis of the various strains’ genomes to understand their diversity and the evolutionary relationships between them.

According to Almeida, the technique used was high-throughput genotyping with SNPs (pronounced “snips” and short for single-nucleotide polymorphisms), which enabled them to identify the genetic composition (genotype) of each strain by means of DNA sequencing. SNPs are the most common markers of genetic variation. The phylogenetic results separated the 90 strains of S. Typhimurium into two groups, A and B.

“The group of samples collected from food differed from the group collected from humans,” Seribelli explained. “Food isolates were distributed between groups A and B in relatively similar numbers, suggesting that more than one subtype is circulating in foods in Brazil. Human isolates were more prevalent in group B, suggesting that a specific subtype has probably adapted to humans.”

In another important part of their research funded by FAPESP, the scientists measured antibiotic resistance in each of the 90 strains. According to the study, 65 (72.2%) of the strains proved resistant to sulfonamides, 44 (48.9%) to streptomycin, 27 (30%) to tetracycline, 21 (23.3%) to gentamicin and seven (7.8%) to ceftriaxone, a cephalosporin antibiotic.

Origin of resistance

The analysis of SNPs identified 39 genes for resistance to different classes of antimicrobial or antibiotic, such as aminoglycoside, tetracycline, sulfonamide, trimethoprim, beta-lactam, fluoroquinolone, phenicol and macrolide. Point mutations were also found in some of the genes, such as gyrA, gyrB, parC and parE.

“It’s striking that S. Typhimurium is resistant to antibiotics that can be used to treat the disease,” Seribelli said. “These drugs are available to physicians for use in combating infections that display resistance. They’re a second line of defense when microorganisms aren’t killed by the patient’s immune system since salmonellosis is normally self-limiting and doesn’t require the use of antibiotics. The main problem is when this fails and the bacteria become invasive.”

Another point that drew the scientists’ attention was the difference between the strains’ resistance over the 30-year sample collection period. “The samples of S. Typhimurium collected in the mid-1990s showed more resistance to antibiotics than samples from later years. This could be explained by the emergence in the early 1990s of the serovar S. Enteritidis, which has since become one of the main causes of salmonella infection,” Seribelli said.

S. Enteritidis has been known since the 1950s, but for a time, it caused fewer cases of the disease. This was radically changed by the S. Enteritidis pandemic, which began in the late 1980s and early 1990s in Europe and then spread around the world.

“Since then, S. Enteritidis has been one of the most prevalent serovars in Brazil and worldwide. As a result, it’s a serovar that can also be combated with antibiotics if necessary,” Seribelli said.

According to Almeida, S. Typhimurium remains one of the main serovars isolated from humans, animals and food in Brazil and worldwide.

As of the S. Enteritidis pandemic in the mid-1990s, the number of resistant strains apparently decreased compared with the number prevalent before the 1990s, but whether the virulence of these strains increased to allow them to adapt to this new niche is unknown.

“The key finding of this research is the discovery of a large number of resistance genes in the samples, considering that they were isolated from humans and food. This points to the very significant risk of contamination in Brazil today from food containing strains of Salmonella that are resistant to antimicrobials,” Almeida said.​

Source:

http://agencia.fapesp.br/isalmonella-i-found-to-be-resistant-to-different-classes-of-antibiotics/29128/

About author

Related Articles