Research Publications (Food Safety)

ICP2 is a virulent bacteriophage (phage) that preys on Vibrio cholerae. ICP2 was first isolated from cholera patient stool samples. Some of these stools also contained ICP2-resistant isogenic V. cholerae strains harboring missense mutations in the trimeric outer membrane porin protein OmpU, identifying it as the ICP2 receptor.

We identified an erm42-carrying integrative and conjugative element, ICE_erm42, in 26.4% of multidrug-resistant Salmonella enterica serovar Albany isolates recovered from cases of human salmonellosis between 2014 and 2019 in Taiwan. ICE_erm42-carrying strains displayed high-level resistance to azithromycin, and the element could move into the phylogenetically distant species Vibrio cholerae via conjugation.

We evaluated human-like the efficacy of intravenous doses of fosfomycin of 8 g every 8 h (8 g/Q8h) and of amikacin (15 mg/kg/Q24h) in monotherapy and in combination against six fosfomycin-heteroresistant Escherichia coli isolates using a hollow-fiber infection model (HFIM). Six fosfomycin-heteroresistant E. coli isolates (four with strong mutator phenotype) and the control strain E. coli ATCC 25922 were used.

Current guidelines recommend against systematic screening for or treating asymptomatic bacteriuria (AB) among kidney transplant (KT) recipients, although the evidence regarding episodes occurring early after transplantation or in the presence of anatomical abnormalities is inconclusive. Oral fosfomycin may constitute a good option for the treatment of posttransplant AB, particularly due to the emergence of multidrug-resistant (MDR) uropathogens.

Polyketide synthase 13 (Pks13) is an important enzyme found in Mycobacterium tuberculosis that condenses two fatty acyl chains to produce α-alkyl β-ketoesters, which in turn serve as the precursors for the synthesis of mycolic acids that are essential building blocks for maintaining the cell wall integrity of M. tuberculosis. Coumestan derivatives have recently been identified in our group as a new chemotype that exerts its antitubercular effects via targeting of Pks13.

Topical antibiotic preparations, such as fusidic acid (FA) or mupirocin, are used in the prevention and treatment of superficial skin infections caused by staphylococci. Previous genomic epidemiology work has suggested an association between the widespread use of topical antibiotics and the emergence of methicillin-resistant Staphylococcus aureus in some settings. In this study, we provide experimental proof of coselection for multidrug resistance in S.

AcrAB-TolC is a major tripartite multidrug efflux pump conferring resistance to a wide variety of compounds in Gram-negative pathogens. Many AcrB mutants have been constructed through site-directed mutagenesis to probe the mechanism of AcrB function in antibiotic resistance. However, much less is known about the actual drug resistance-related mutants that naturally occur in clinically isolated pathogens.

The use of colistin as a last-resort antimicrobial is compromised by the emergence of resistant enterobacteria with acquired determinants like mcr genes, mutations that activate the PmrAB system, or still unknown mechanisms. This work analyzed 74 Escherichia coli isolates from healthy swine, turkey, or bovine, characterizing their colistin resistance determinants.

Author(s): Yingshu He, Ruixi Chen, Yan Qi, Joelle K. Salazar, Shimei Zhang, Mary Lou Tortorello, Xiangyu Deng, Wei Zhang

Antimicrobial resistance is recognized as one of the major global health challenges of the 21st century. Synergistic combinations for antimicrobial therapies can be a good strategy for the treatment of multidrug resistant infections. We examined the ability of a group of 29 plant essential oils as substances which enhance the antibiotic activity.

Author(s): Adrian M. Whatmore, Jeffrey T. Foster

The potential employment of 18 commercial Tunisian essential oils (EOs) as natural food preservatives was investigated. Their antimicrobial activity was evaluated against two food-borne bacteria (Escherichia coli O157:H7 and Klebsiella pneumoniae) by the agar-well diffusion method and, subsequently, by determining the minimum inhibitory concentration (MIC); while their antioxidant activity was assayed by the DPPH test.

Author(s): Woorim Yeom, Hoikyung Kim, Larry R. Beuchat, Jee-Hoon Ryu

Author(s): Marcela Suárez-Esquivel, Nazareth Ruiz-Villalobos, Warren Hidalgo-Jara, Carlos Chacón-Díaz, Ana Mariel Zúñiga-Pereira, Mario Masís-Mora, Ericka Fernández-Fernández, Gabriela Hernández-Mora, Elías Barquero-Calvo, Esteban Chaves-Olarte, Nicholas R. Thomson, Jeffrey T. Foster, Edgardo Moreno, Caterina Guzmán Verri

This study aimed to evaluate the effects of beef patty formulations and pressure levels on the inactivation of spoilage microbiota and native Shiga toxin-producing Escherichia coli (STEC) O157:H7. Beef patties were made with different salt and fat content (A: 1% NaCl – 10% fat, B: 2% NaCl – 10% fat, C: 1% NaCl – 20% fat and D: 2% NaCl – 20% fat) and treated at 400 and 600 MPa. STEC reductions after 400 and 600 MPa were 2 and 4 log CFU/g, respectively.

The Staphylococcus aureus Tet38 membrane protein has distinct functions, including drug efflux and host cell attachment and internalization mediated by interaction with host cell CD36. Using structural modeling and site-directed mutagenesis, we identified key amino acids involved in different functions. Tet38, a member of the major facilitator superfamily, is predicted to have 14 transmembrane segments (TMS), 6 cytoplasmic loops, and 7 external loops.

Listeria monocytogenes is a Gram-positive, intracellular pathogen that is highly adapted to invade and replicate in the cytosol of eukaryotic cells. Intermediate metabolites in the menaquinone biosynthesis pathway are essential for the cytosolic survival and virulence of L. monocytogenes, independent of the production of menaquinone (MK) and aerobic respiration.

Enterotoxigenic Escherichia coli (ETEC) contributes significantly to the substantial burden of infectious diarrhea among children living in low- and middle-income countries. In the absence of a vaccine for ETEC, children succumb to acute dehydration as well as nondiarrheal sequelae related to these infections, including malnutrition.

Enterohemorrhagic Escherichia coli (EHEC) infections can result in a wide range of clinical presentations despite that EHEC strains belong to the O157:H7 serotype, one of the most pathogenic forms. Although pathogen virulence influences disease outcome, we emphasize the concept of host-pathogen interactions, which involve resistance or tolerance mechanisms in the host that determine total host fitness and bacterial virulence.

Author(s): G.K. Sivaraman, K.H. Muneeb, S. Sudha, Bibek Shome, Jennifer Cole, Mark Holmes

Author(s): R. Kaavya, R. Pandiselvam, S. Abdullah, N.U. Sruthi, Yasendra Jayanath, C. Ashokkumar, Anandu Chandra Khanashyam, Anjineyulu Kothakota, S.V. Ramesh

Methicillin-resistant Staphylococcus aureus is one of the major clinical problems in hospitals because of its resistance to many antimicrobials. Biocides are used in hospitals to control nosocomial infections. This work aimed to investigate the relationship between the presence of integrons and reduced susceptibility to both biocides and antimicrobials in nosocomial multidrug-resistant (MDR)-MRSA isolates.

The continual increase in resistance to antibacterial drugs has become a major public health problem, and their indiscriminate use in agriculture, aquaculture, and the treatment of human and animal diseases has severely contributed to the occurrence and spread of multidrug resistance genes. This study phylogenetically characterized multidrug-resistant bacteria isolated from seafood cocktails. Seafood cocktail dishes from 20 establishments on public roads were sampled.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widespread in European pig production, and an increasing number of humans attract infections with this bacterium. Although most infections occur in humans with direct livestock contact, an increasing number of infections occur in humans without any established livestock contact.