ANTIBACTERIAL, ANTIFUNGAL AND ANTIOXIDANT ACTIVITIES OF TUNISIAN OLEA EUROPAEA SSP. OLEASTER FRUIT PULP AND ITS ESSENTIAL FATTY ACIDS

Objective: This study was conceived to evaluate the essential fatty acids, secondary metabolite, antimicrobial and antioxidant activities of Olea europaea ssp. oleaster fruits pulp methanolic extract.Methods: Analysis of the lipid content from unexploited Olea europaea ssp. oleaster pulp was carried out using gas chromatography. The antioxidant activity was evaluated by DPPH radical scavenging. The antimicrobial activity was also tested against seven pathogenic bacteria, two fungal species and one yeast strain using two methods.Results: The obtained results showed that the major components of fatty acids were oleic acid (77.4%) and elaidic acid (17.58%). Moreover, the tested extract was rich in phenol (84.04±0.01 mg GAE/g DW) than in flavonoids (60.41±0.02 mg RE/g DW). In addition, it showed puissant antioxidant (IC50 = 28±0.01 µg/mL), antibacterial and antifungal activities. The inhibition zones diameters and the minimum inhibition concentration values for tested microorganisms were in the range of 13-18 mm and 3.125-25 mg/mL, respectively.Conclusion: This study shows that Olea europaea ssp. oleaster fruit pulp could be developed into ingredients for use in foods as the natural antioxidant and antimicrobial agent

Molecular characterisation of antimicrobial resistance and virulence genes in Escherichia coli strains isolated from diarrhoeic and healthy rabbits in Tunisia

[EN] The purpose of this study was to identify Escherichia coli isolates in diarrhoeic and healthy rabbits in Tunisia and characterise their virulence and antibiotic resistance genes. In the 2014-2015 period, 60 faecal samples from diarrhoeic and healthy rabbits were collected from different breeding farms in Tunisia. Susceptibility to 14 antimicrobial agents was tested by disc diffusion method and the mechanisms of gene resistance were evaluated using polymerase chain reaction and sequencing methods. Forty E. coli isolates were recovered in selective media. High frequency of resistance to tetracycline (95%) was detected, followed by different levels of resistance to sulphonamide (72.5%), streptomycin (62.5%), trimethoprim-sulfamethoxazole (60%), nalidixic acid (32.5%), ampicillin (37.5%) and ticarcillin (35%). E. coli strains were susceptible to cefotaxime, ceftazidime and imipenem. Different variants of blaTEM, tet, sul genes were detected in most of the strains resistant to ampicillin, tetracycline and sulphonamide, respectively. The presence of class 1 integron was studied in 29 sulphonamide-resistant E. coli strains from which 15 harboured class 1 integron with four different arrangements of gene cassettes, dfrA17+aadA5 (n=9), dfrA1 + aadA1 (n=4), dfrA12 + addA2 (n=1), dfrA12+orf+addA2 (n=1). The qnrB gene was detected in six strains out of 13 quinolone-resistant E. coli strains. Seventeen E. coli isolates from diarrhoeic rabbits harboured the enteropathogenic eae genes associated with different virulence genes tested (fimA, cnf1, aer), and affiliated to B2 (n=8) and D (n=9) phylogroups. Isolated E. coli strains from healthy rabbit were harbouring fim A and/or cnf1 genes and affiliated to A and B1 phylogroups. This study showed that E. coli strains from the intestinal tract of rabbits are resistant to the widely prescribed antibiotics in medicine. Therefore, they constitute a reservoir of antimicrobial-resistant genes, which may play a significant role in the spread of antimicrobial resistance. In addition, the eae virulence gene seemed to be implicated in diarrhoea in breeder rabbits in Tunisia.The work was supported by Tunisian Ministry of Higher Education, Scientific Research and Technology (LR16IP03). Many thanks go to the members of the Department of Animal Production, National Institute of Agronomy of Tunisia for their help in collecting the samples.Ben Rhouma, R.; Jouini, A.; Klibi, A.; Hamrouni, S.; Boubaker, A.; Kmiha, S.; Maaroufi, A. (2020). Molecular characterisation of antimicrobial resistance and virulence genes in Escherichia coli strains isolated from diarrhoeic and healthy rabbits in Tunisia. World Rabbit Science. 28(2):81-91. https://doi.org/10.4995/wrs.2020.10879OJS8191282Allen H.K., Donato J., Wang H.H, Cloud-Hansen K.A., Davies J. 2010. Call of the wild: antibiotic resistance genes in natural environments. Nat. Rev. Microbiol., 8: 251-259. https://doi.org/10.1038/nrmicro2312Allocatti N., Masulli M., Alexeyev M.F., Di Ilio C. 2013. Escherichia coli in Europe: An overview. Int. J. Environ. Res. Public Health., 10: 6235-6254. https://doi.org/10.3390/ijerph10126235Alonso C.A., Zarazaga M., Ben Sallem R., Jouini A., Ben Slama K., Torres C. 2017. Antibiotic resistance in Escherichia coli in Husbandry animals. The African perspective. Lett. Appl. Microbiol., 64: 318-334. https://doi.org/10.1111/lam.12724Barbosa T.M., Levy S.B. 2000. The impact of antibiotic use on resistance development and persistence. Drug Resist. Updates, 5: 303-311. https://doi.org/10.1054/drup.2000.0167Ben Said L., Jouini A., Klibi N., Dziri R., Alonso C.A., Boudabous A., Ben Slama K., Torres C. 2015. Detection of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in vegetables, soil and water of farm environment in Tunisia. Int. J. Food Microbiol., 203: 86-92. https://doi.org/10.1016/j.ijfoodmicro.2015.02.023Ben Sallem R.B., Gharsa H., Slama K.B.., Rojo-Bezares B, Estepa V., Porres-Osante N., Jouini A., Klibi N., Sáenz Y., Boudabous A., Torres C. 2013. First detection of CTX-M-, CMY-2, and QnrB19 resistance mechanisms in fecal Escherichia coli isolates from healthy pets in Tunisia. Vector Borne Zoonotic Dis., 13: 98-102. https://doi.org/10.1089/vbz.2012.1047Ben Slama K., Jouini A., Ben Sallem R., Somalo S., Sáenz Y., Estepa V., Boudabous A., Torres C. 2010. Prevalence of broad-spectrum cephalosporin-resistant Escherichia coli isolates in food samples in Tunisia and characterization of integrons and antimicrobial resistance mechanisms implicated. Int. J. Food Microbiol., 13: 281-286. https://doi.org/10.1016/j.ijfoodmicro.2009.12.003Ben Slama K., Ben Sallem R., Jouini A., Rachid S., Moussa L., Saenz Y., Estepa V., Somalo S., Boudabous A., Torres C. 2011. Diversity of genetic lineages among CTX-M-15 and CTX-M-14 producing Escherichia coli strains in a Tunisian hospital. Curr. Microbiol., 62: 1794-1801. https://doi.org/10.1007/s00284-011-9930-4Blanco J.E., Blanco M., Blanco J., Mora A., Balaguer L., Mourino M., JuÁrez A., Jansen W.H. 1996. O serogroups, biotypes, and eae genes in Escherichia coli strains isolated from diarrheic and healthy rabbits. J. Clin. Microbiol., 34: 3101- 3107. https://doi.org/10.1128/JCM.34.12.3101-3107.1996Blanco M., Blanco J.E., Dahbi G., Alonso M.P., Mora A., Corira M.A.A., Madrid C., Juárez A., Bernárdez M.I., González E.A., Blanco J. 2006. Identification of two new intimin types in atypical enteropathogenic Escherichia coli. Int. Microbiol., 9: 103-110.Brinas L., Zarazaga M., Saenz Y., Ruiz-Larrea F., Torres C. 2002. Beta-lactamases in ampicillin-resistant Escherichia coli isolates from foods, humans, and healthy animals. Antimicrob. Agents Chemother., 46: 3156-3163. https://doi.org/10.1128/AAC.46.10.3156-3163.2002Bryan A., Shapir N., Sadowsky M.J. 2004. Frequency and distribution of tetracycline resistance genes in genetically diverse, nonselected and nonclinical Escherichia coli strains isolated from diverse human and animal sources. Appl. Environ. Microbiol., 70: 2503-2507. https://doi.org/10.1128/AEM.70.4.2503-2507.2004Camarda A., Pennelli D., Battista P., Martella V., Greco L., Alloggio I., Mazzolini E. 2004. Virulence genes and antimicrobial resistance patterns of enteropathogenic Escherichia coli from rabbits in southern Italy. In Proc.: 8th World Rabbit Congress., September 7-10, 2004, Puebla, Mexico, 470-476.Clermont O., Bonacorsi S., Bingen E., 2000. Rapid and simple determination of the Escherichia coli phylogenetic group. Appl. Environ. Microb., 66: 4555-4558. https://doi.org/10.1128/AEM.66.10.4555-4558.2000Clermont O., Lavolly M., Vimont S., Deschamps C., Forestier C., Branger C., Denamur E., Arlet G. 2008. The CTX-M15-producing Escherichia coli diffusing clone belongs to a highly virulent B2 phylogenic subgroup. J. Antimicrob. Chemother., 61: 1024-1028. https://doi.org/10.1093/jac/dkn084Clinical and Laboratory Standards Institute. 2015. Performance standards for antimicrobial susceptibility testing. Twenty-fifth informational supplement. Clinical and Laboratory Standards Institute document M100-S25, CLSI, Wayne, PA.Coque T.M., Novais A., Carattoli A., Poirel L., Pitout J., Peixe L., Baquero F., Cantón R., Nordmann P. 2008. Dissemination of clonally related Escherichia coli strains expressing extendedspectrum β-lactamase CTX-M-15. Emerg. Infect. Dis., 14: 195-200. https://doi.org/10.3201/eid1402.070350Da Costa P.M., Loureiro L., Matos A.J.F. 2013. Transfer of Multidrug-Resistant Bacteria between intermingled ecological niches: the interface between Humans, Animals and the environment. Int. J. Environ. Res. Public Health., 10: 278-294. https://doi.org/10.3390/ijerph10010278Dotto G., Giacomelli M., Grilli G., Ferrazzi V., Carattoli A., Fortini D., Piccirillo A. 2014. High prevalence of oqxAB in Escherichia coli isolates from domestic and wild lagomorphs in Italy. Microb. Drug Resist., 20: 118-123. https://doi.org/10.1089/mdr.2013.0141Eager H., Swan G., van Vuuren M. 2015. A survey of antimicrobial usage in animals in South Africa 479 with specific reference to food animals. J. S. Afr. Vet. Assoc., 83: 16. https://doi.org/10.4102/jsava.v83i1.16Guardabassi L., Schwarz S., Lloyd D.H., 2004. Pet animals as reservoirs of antimicrobial-resistant bacteria. J. Antimicrob. Chemother., 54: 321-332. https://doi.org/10.1093/jac/dkh332Hai S.W., Qi R.P., Y. Gao M. et al. 2014. Study on molecular characterization of Class I integron and integron-associated antimicrobial resistance in Escherichia coli from beef cattle. China Animal Husbandry Veterinary Medicine., 41: 63-67.Jacoby G.A., Griffin C., Hooper D.C. 2011. Citrobacter spp. as a source of qnrB alleles. Antimicrob. Agents Chemother., 55: 4979-4984. https://doi.org/10.1128/AAC.05187-11Johnson T.J., Logue C.M., Johnson J.R., Kuskowski M.A., Sherwood J.S., Barnes H.J., DebRoy C., Wannemuehler Y.M., Obata-Yasuoka M., Spanjaard L., Nolan L.K. 2012. Associations between multidrug resistance, plasmid content, and virulence potential among extra-intestinal pathogenic and commensal Escherichia coli from humans and poultry. Foodborne Pathog. Dis., 9: 37-46. https://doi.org/10.1089/fpd.2011.0961Jouini A., Ben Slama K., Saenz Y., Klibi N., Costa D., Vinué L., Zarazaga M., Boudabous A., Torres C. 2009. Detection of Multiple-Antimicrobial Resistance and Characterization of the Implicated Genes in Escherichia coli isolates from Foods of Animal Origin in Tunis. J. Food Protect., 72: 1082-1088. https://doi.org/10.4315/0362-028X-72.5.1082Kaper J.B., Nataro J.P., Mobley H.L. 2004. Pathogenic Escherichia coli. Nat. Rev. Microbiol., 2: 123-140. https://doi.org/10.1038/nrmicro818Lauková A., Strompfová V., Szabóová R., Bónai A., Matics Z., Kovács M., Pogány Simonová M. 2019. Enterococci from pannon white rabbits: detection, identification, biofilm and screening for virulence factors. World Rabbit Sci., 27: 31-39. https://doi.org/10.4995/wrs.2019.10875Marinho C., Igrejas G., Gonçalves A., Silva N., Santos T., Monteiro R., Gonçalves D., Rodrigues T., Poeta P. 2014. Azorean wild rabbits as reservoirs of antimicrobial resistant Escherichia coli. Anaerobe, 30: 116-119. https://doi.org/10.1016/j.anaerobe.2014.09.009Panteado A.S., Ugrinivich L.A., Blanco J., Blanco M., Andrade J.R.C., Correa S.S., De Castro A.F.P. 2002. Serobiotypes and virulence genes of Escherichia coli strains isolated from diarrheic and healthy rabbits in Brazil. Vet. Microb., 89: 41-51. https://doi.org/10.1016/S0378-1135(02)00148-7Pohl P.H., Peeters J.E.E., Jacquemin R., Lintermans P.F., Mainil J.G. 1993. Identification of eae sequences in enteropathogenic Escherichia coli strains from rabbits. Infect. Immun., 61: 2203-2206. https://doi.org/10.1128/IAI.61.5.2203-2206.1993Poirel L., Bonnin R.A., Nordmann P. 2012. Genetic support and diversity of acquired extended-spectrum beta-lactamases in Gram-negative rods. Infect. Genet. Evol., 12: 883-893. https://doi.org/10.1016/j.meegid.2012.02.008Qing F.K., Yi G., Ze H.Y., YA J.L., Wei H.M., Zhao B.D., Yu W.Z., Guan W. 2006. Detection of quinolone resistance and plasmid mediated quinolone gene in Escherichia coli isolated from rabbit. Chin. J. Prev. Vet. Med., 38: 944-948.Ruiz J., Simon K., Horcajada J.P., Velasco M., Barranco M., Roig G., Moreno-Martínez A., Martínez J.A., Jiménez de Anta T., Mensa J., Vila J. 2002. Differences in virulence factors among clinical isolates of Escherichia coli causing cystitis and pyelonephritis in women and prostatitis in men. J. Clin. Microbiol., 40: 4445-4449. https://doi.org/10.1128/JCM.40.12.4445-4449.2002Sáenz Y., Zarazaga M., Briñas L., Lantero M., Ruiz-Larrea F., Torres C. 2001. Antibiotic resistance in Escherichia coli isolates obtained from animals, foods and humans in Spain. Int. J. Antimicrob. Agents.,18: 353-358. https://doi.org/10.1016/S0924-8579(01)00422-8Saenz Y., Briñas L., Domínguez E., Ruiz J., Zarazaga M., Vila J., Torres C. 2004. Mechanisms of resistance in multiple-antibio resistant Escherichia coli strains of human, animal, and food origins. Antimicrob. Agents Chemother., 48: 3996-4001. https://doi.org/10.1128/AAC.48.10.3996-4001.2004Santos T., Silva N., Igrejas G, Rodrigues P., Micael J., Rodrigues T., Resendes R., Gonçalves A., Marinho C., Gonçalves D., Cunha R., Poeta P. 2013. Dissemination of antibiotic resistant Enterococcus spp. and Escherichia coli from wild birds of Azores Archipielago. Anaerobe., 24: 25-31. https://doi.org/10.1016/j.anaerobe.2013.09.004Silva N., Igrejas G., Figueiredo N., Gonçalves, A., Radhouani H., Rodrigues J., Poeta P. 2010. Molecular characterization of antimicrobial resistance in enterococci and Escherichia coli isolates from European wild rabbit (Oryctolagus cuniculus). Sci Total Environ., 408: 4871-4876. https://doi.org/10.1016/j.scitotenv.2010.06.046Swennes A.G., Buckley E.M., Parry N.M.A., Madden C.M., Garcia A., Morgan P.B., Astrofsky K.M., Fox J.G. 2012. Enzootic Enteropathogenic Escherichia coli Infection in Laboratory Rabbits. J. Clin. Microbiol., 50: 2353-2358. https://doi.org/10.1128/JCM.00832-12Teshager T., Herrero I.A., Porrero M.C., Garde J., Moreno M.A., Domínguez L. 2000. Surveillance of antimicrobial resistance in Escherichia coli strains isolated from pigs at Spanish slaughterhouses. Int. J. Antimicrob. Agents, 15: 137-142. https://doi.org/10.1016/S0924-8579(00)00153-9Van den Bogaard A.E., London N., Stobberingh E.E. 2000. Antimicrobial resistance in pig faecal samples from The Netherlands (five abattoirs) and Sweden. J. Antimicrobial Chemother., 45: 663-671. https://doi.org/10.1093/jac/45.5.663Wang J., Sang L., Chen Y., Sun S., Chen D., Xie X. 2019. Characterisation of Staphylococcus aureus strain causing severe respiratory disease in rabbits. World Rabbit Sci., 27: 41-48. https://doi.org/10.4995/wrs.2019.10454Werner G., Gfrörer S., Fleige C., Witte W., Klare I. 2008. Tigecycline-resistant Enterococcus faecalis strain isolated from a German ICU patient. J. Antimicrob Chemother., 61: 1182-1183. https://doi.org/10.1093/jac/dkn065Yoon S.H., Jeong H., Kwon S.K., Kim J.F. 2009. Genomics, Biological Features, and Biotechnological Applications of Escherichia coli B: Is B for better. In: Lee S.Y. (eds). Systems Biology and Biotechnology of Escherichia coli., 1-17. https://doi.org/10.1007/978-1-4020-9394-4_1Zhao X., Yang J., Ju Z., Chang W., Sun S. 2018. Molecular characterization of antimicrobial resistance in Escherichia coli from rabbit farms in Tai'an, China. Hindawi, Biomed Research International., 2018: 1-7. https://doi.org/10.1155/2018/860764

Detection of Extended-Spectrum β-Lactamases (ESBL) Producing Enterobacteriaceae from Fish Trapped in the Lagoon Area of Bizerte, Tunisia

Extended-spectrum β-lactamase and their molecular mechanism in Enterobacteriaceae were analyzed in 126 fish samples of 9 various wild species, living in the lagoon of Bizerte in Tunisia. Fifty-nine (59) Gram-negative strains were isolated and identified as Escherichia coli (n=24), Klebsiella pneumonia (n=21), Citrobacter freundii (n=8), and Shigella boydii (n=6). Forty-seven ESBL producers were identified using the synergic test. β-Lactamase genes detected were blaCTX-M-1 (E. coli/15; K. pneumonia/8; C. freundii/1; Sh. boydii/1), blaCTX-M-1+ blaOXA-1 (E. coli/4; K. pneumonia/3), blaCTX-M-1+ blaTEM-1-a (K. pneumonia/2), blaCTX-M-15+ blaTEM-1-a (K. pneumonia/1; Sh. boydii/1), blaCTX-M-15+ blaOXA-1 (K. pneumonia/1), blaCTX-M-15 (E. coli/3; K. pneumonia/1; Sh. boydii/3), and blaCTX-M-9 (C. freundii/3). Most strains (84.7%) showed a multiresistant phenotype. qnrA and qnrB genes were identified in six E. coli and in ten E. coli+one K. pneumonia isolates, respectively. The resistance to tetracycline and sulfonamide was conferred by the tet and sul genes. Characterization of phylogenic groups in E. coli isolates revealed phylogroups D (n=20 strains), B2 (n=2), and A (n=2). The studied virulence factor showed prevalence of fimA genes in 9 E. coli isolates (37.5%). Similarly, no strain revealed the three other virulence factors tested (eae, aer, and cnf1). Our findings confirmed that the lagoons of Bizerte may be a reservoir of multidrug resistance/ESBL-producing Enterobacteriaceae. This could lead to indisputable impacts on human and animal health, through the food chain

Characterization of Primary Action Mode of Eight Essential Oils and Evaluation of Their Antibacterial Effect against Extended-Spectrum β-Lactamase (ESBL)-Producing <i>Escherichia coli</i> Inoculated in Turkey Meat

The current study aims to evaluate the antimicrobial activity of eight essential oils (EOs) against multidrug-resistant Escherichia coli strains, producing extended-spectrum β-lactamase (ESBL) enzymes and isolated from foods. Disc-diffusion assay showed that the inhibition diameters generated by EOs varied significantly among the tested EOs and strains. In fact, EOs extracted from Thymus capitaus, Eucalyptus camaldulensis, Trachyspermum ammi and Mentha pulegium exerted an important antimicrobial effect against tested strains, with the diameters of inhibition zones varied between 20 and 27 mm. Moreover, minimal inhibition and bactericidal concentration (MIC and MBC) values demonstrated that T. capitatus EOs generate the most important inhibitory effect against E. coli strains, with MIC values ranging from 0.02 to 0.78%. Concerning the mode of action of T. capitatus EO, the obtained data showed that treatment with this EO at its MIC reduced the viability of E. coli strains, their tolerance to NaCl and promoted the loss of 260-nm-absorbing material. In addition, in the presence of T. capitatus EO, cells became disproportionately sensitive to subsequent autolysis. Moreover, the inhibitory effect of T. capitatus was evaluated against two E. coli strains, experimentally inoculated (105 CFU/g) in minced turkey meat, in the presence of two different concentrations of EO (MIC and 2 × MIC), and stored for 15 days. In both samples, EO exerted a bacteriostatic effect in the presence of concentrations equal to MIC. Interestingly, at 2 × CMI concentration, the bactericidal activity was pronounced after 15 days of storage. Our results highlighted that the use of essential oils, specially of T. capitatus, to inhibit or prevent the growth of extended-spectrum β-lactamase (ESBL)-producing E. coli in food, may be a promising alternative to chemicals

Methicillin-Resistant <i>Staphylococcus</i> <i>aureus</i> Strains Isolated from Burned Patients in a Tunisian Hospital: Molecular Typing, Virulence Genes, and Antimicrobial Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major causes of a variety of infections in hospitals and the community. Their spread poses a serious public health problem worldwide. Nevertheless, in Tunisia and other African countries, very little molecular typing data on MRSA strains is currently available. In our study, a total of 64 MRSA isolates were isolated from clinical samples collected from burned patients hospitalized in the Traumatology and Burns Center of Ben Arous in Tunisia. The identification of the collection was based on conventional methods (phenotypic and molecular characterization). The characterization of the genetic support for methicillin resistance was performed by amplification of the mecA gene by polymerase chain reaction (PCR), which revealed that 78.12% of S. aureus harbors the gene. The resistance of all the collection to different antibiotic families was studied. Indeed, the analysis of strain antibiotic susceptibility confirmed their multi-resistant phenotype, with high resistance to ciprofloxacin, gentamicin, penicillin, erythromycin, and tetracycline. The resistance to the last three antibiotics was conferred by the blaZ gene (73.43%), the erm(C) gene (1.56%), the msr(A) gene (6.25%), and tet(M) gene (7.81%), respectively. The clonal diversity of these strains was studied by molecular typing of the accessory gene regulator (agr) system, characterization of the SCCmec type, and spa-typing. The results revealed the prevalence of agr types II and III groups, the SCCmec type III and II cassettes, and the dominance of spa type t233. The characterization of the eight enterotoxins genes, the Panton-Valentine leukocidin and the toxic shock syndrome toxin, was determined by PCR. The percentage of virulence genes detected was for enterotoxins (55%), tst (71.88%), leukocidin E/D (79.69%), and pvl (1.56%) factors. Furthermore, our results revealed that the majority of the strains harbor IEC complex genes (94%) with different types. Our findings highlighted the emergence of MRSA strains with a wide variety of toxins, leukocidin associated with resistance genes, and specific genetic determinants, which could constitute a risk of their spread in hospitals and the environment and complicate infection treatment

Lineages, Virulence Gene Associated and Integrons among Extended Spectrum &beta;-Lactamase (ESBL) and CMY-2 Producing Enterobacteriaceae from Bovine Mastitis, in Tunisia

Extended Spectrum Beta-Lactamase (ESBL) Enterobacteriaceae are becoming widespread enzymes in food-producing animals worldwide. Escherichia coli and Klebseilla pneumoniae are two of the most significant pathogens causing mastitis. Our study focused on the characterization of the genetic support of ESBL/pAmpC and antibiotic resistance mechanisms in cefotaxime-resistant (CTXR) and susceptible (CTXS) Enterobacteriaceae isolates, recovered from bovine mastitis in Tunisia, as well as the analyses of their clonal lineage and virulence-associated genes. The study was carried out on 17 ESBL/pAmpC E. coli and K. pneumoniae and 50 CTXS&nbsp;E. coli. Detection of resistance genes and clonal diversity was performed by PCR amplification and sequencing. The following &beta;-lactamase genes were detected: blaCTX-M-15 (n = 6), blaCTX-M-15 + blaOXA-1 (2), bla CTX-M-15 + blaOXA-1 + blaTEM-1b (2), blaCTX-M-15 + blaTEM-1b (4), blaCMY-2 (3). The MLST showed the following STs: ST405 (n = 4 strains); ST58 (n = 3); ST155 (n = 3); ST471 (n = 2); and ST101 (n = 2). ST399 (n = 1) and ST617 (n = 1) were identified in p(AmpC) E. coli producer strains. The phylogroups A and B1 were the most detected ones, followed by the pathogenic phylogroup B2 that harbored the shigatoxin genes stx1/stx2, associated with the cnf, fimA, and aer virulence factors. The qnrA/qnrB, aac(6&prime;)-Ib-cr genes and integrons class 1 with different gene cassettes were detected amongst these CTXR/S isolated strains. The presence of different genetic lineages, associated with resistance and virulence genes in pathogenic bacteria in dairy farms, may complicate antibiotic therapies and pose a potential risk to public health

Essential Oils from Thymus capitatus and Thymus algeriensis as Antimicrobial Agents to Control Pathogenic and Spoilage Bacteria in Ground Meat

The antibacterial effects of essential oils (EOs) extracted from Thymus capitatus and Thymus algeriensis were assessed and evaluated against four pathogenic bacteria (Escherichia coli (ATCC 25922), Listeria monocytogenes (ATCC 19118), Staphylococcus aureus (ATCC 25923), and Salmonella typhimurium (ATCC 1402)) and one spoilage bacterium (Pseudomonas aeruginosa (ATCC 27853)). Both investigated EOs presented significant antimicrobial activities against all tested bacteria with a greater antibacterial effect of T. capitatus EO. In fact, the results indicated that the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of T. capitatus EO are in the range of 0.006–0.012% and 0.012–0.025%, respectively, while those of T. algeriensis EO ranged between 0.012 and 0.025% and 0.05%, respectively. Furthermore, the inhibitory effects of both EOs were appraised against the spoilage bacterium P. aeruginosa, inoculated in minced beef meat, at two different loads (105 and 108 CFU) mixed with different concentrations of EOs (0.01, 0.05, 1, and 3%) and stored at 4°C for 15 days. The obtained data demonstrated that the antibacterial effect of tested EOs varies significantly in regard to the levels of meat contamination and the concentrations of EOs. In fact, in the presence of 0.01 and 0.05% of oils, a decrease in bacterial growth p<0.01 was observed; but, such an effect was more pronounced in the presence of higher concentrations of EOs (1 and 3%), regardless the level of meat contamination. Besides, at the low contamination level, both EOs exerted a rapid and a more pronounced antibacterial effect, as compared to the high contamination level. The results illustrated the efficacy of both EOs as preservatives in food against well-known pathogens of food-borne diseases and food spoilage, particularly in P. aeruginosa in beef meat. As regards sensory evaluation, the presence of T. capitatus EO proved to improve the sensory quality of minced beef meat

First Detection of Human ST131-CTX-M-15-O25-B2 Clone and High-Risk Clonal Lineages of ESBL/pAmpC-Producing E. coli Isolates from Diarrheic Poultry in Tunisia

International audienceCirculation of a multi-resistance clone of bacteria associated with genetic elements in diseased animals constitutes a global public health problem. Our study focused on the characterization of the support of ESBL in cefotaxime resistant E. coli (CTXR) isolates recovered from poultry with diarrhea, analysis of their clonal lineage, and virulence-associated genes. The study was carried out on 130 samples of chickens with diarrhea, collected in 2015 from poultry farms in Tunisia. Isolates of 20 CTXR E. coli strains were identified as ESBL and AmpC β- lactamase producers. The following β-lactamase genes (number of isolates) were detected: blaCTX-M-15+ blaOXA1 (4), blaCTX-M-15 + blaOXA1 + blaTEM-1b (2), blaCTX-M-1 + blaTEM-1b (9), blaCTX-M-1 (2), blaCMY2 + blaTEM-1b (3). Six E. coli harboring blaCTXM-15 were allocated to ST131-B2-O25b-; six and three blaCTX-M-1 were grouped in ST155, ST10, and ST58, respectively, related to the phylogroup D and A. The qnrB gene, the variant aac(6′)-Ib-cr, and the class 1 integrons with different gene cassettes, were detected amongst our 20 isolated strains, which were classified as ExPEC and aEPEC. Our findings highlighted the emergence of the human pandemic ST131-CTX-M-15-O25-B2 clone and the high risk of such clonal lineage strains in diarrheic poultry, in Tunisia, which could constitute a risk of their transfer to healthy animals and humans