Authors:Ama Szmolka, Barbara Lestár, Judit Pászti, Péter Z. Fekete, and Béla Nagy
Enterotoxigenic E. coli (ETEC) bacteria frequently cause watery diarrhoea in newborn and weaned pigs. Plasmids carrying genes of different enterotoxins and fimbrial adhesins, as well as plasmids conferring antimicrobial resistance are of prime importance in the epidemiology and pathogenesis of ETEC. Recent studies have revealed the significance of the porcine ETEC plasmid pTC, carrying tetracycline resistance gene tet(B) with enterotoxin genes. In contrast, the role of tet(A) plasmids in transferring resistance of porcine ETEC is less understood. The objective of the present study was to provide a comparative analysis of antimicrobial resistance and virulence gene profiles of porcine post-weaning ETEC strains representing pork-producing areas in Central Europe and in the USA, with special attention to plasmids carrying the tet(A) gene. Antimicrobial resistance phenotypes and genotypes of 87 porcine ETEC strains isolated from cases of post-weaning diarrhoea in Austria, the Czech Republic, Hungary and the Midwest USA was determined by disk diffusion and by PCR. Central European strains carrying tet(A) or tet(B) were further subjected to molecular characterisation of their tet plasmids. Results indicated that > 90% of the ETEC strains shared a common multidrug resistant (MDR) pattern of sulphamethoxazole (91%), tetracycline (84%) and streptomycin (80%) resistance. Tetracycline resistance was most frequently determined by the tet(B) gene (38%), while tet(A) was identified in 26% of all isolates with wide ranges for both tet gene types between some countries and with class 1 integrons and resistance genes co-transferred by conjugation. The virulence gene profiles included enterotoxin genes (lt, sta and/or stb), as well as adhesin genes (k88/f4, f18). Characterisation of two representative tet(A) plasmids of porcine F18+ ETEC from Central Europe revealed that the IncF plasmid (pES11732) of the Czech strain (~120 kb) carried tet(A) in association with catA1 for chloramphenicol resistance. The IncI1 plasmid (pES2172) of the Hungarian strain (~138 kb) carried tet(A) gene and a class 1 integron with an unusual variable region of 2,735 bp composed by two gene cassettes: estX-aadA1 encoding for streptothricin-spectinomycin/streptomycin resistance exemplifying simultaneous recruitment, assembly and transfer of multidrug resistance genes by the tet(A) plasmid of porcine ETEC. By this we provide the first description of IncF and IncI1 type plasmids of F18+ porcine enterotoxigenic E. coli responsible for cotransfer of the tet(A) gene with multidrug resistance. Additionally, the unusual determinant estX, encoding for streptothricin resistance, is first reported here in porcine enterotoxigenic E. coli.
Authors:Barbara Ujvári, László Makrai, and Tibor Magyar
San Millan , A. , Escudero , J. A. , Gutierrez , B. , Hidalgo , L. , Garcia , N. , Llagostera , M. , Dominguez , L. and Gonzalez-Zorn , B. ( 2009 ): Multiresistance in Pasteurella multocida is mediated by coexistence of small plasmids
Authors:Ervin Albert, Rita Sipos, Szilárd Jánosi, Péter Kovács, Árpád Kenéz, Adrienn Micsinai, Zsófia Noszály, and Imre Biksi
but two strains were resistant to at least three or more classes of antimicrobial agents, fulfilling the term of multiresistance. The antibiogram also helps to allocate the recovered isolates to the most probable host group. For instance, tetracycline
Authors:Raquel Santos, Miguel Grilo, Mónica Araújo, José Luís Monteiro, and Manuela Oliveira
third of the Gram-positive cocci ( n = 10, 27.7%) presented a multiresistance profile, which is characterized by resistance to more than three classes of antimicrobial compounds.
The double-disk test for macrolide resistance characterization
Authors:Hafsa Lamrani Alaoui, Khalid Oufdou, and Nour-Eddine Mezrioui
The dynamic and antibiotic resistance of faecal coliforms, faecal streptococci and
, isolated by standard membrane filtration methods from suburban and rural untreated groundwater supplies, were scrutinized in this study. The annual average densities of these bacteria were respectively 1891 colony forming units (c.f.u.)/100 mL, 1246 c.f.u./100 mL and 206 c.f.u./100 mL. The total occurrence of faecal coliforms and faecal streptococci during the period of study was 94%. Detectable
was present in 88% of samples. A total of 320 faecal coliforms, 338 faecal streptococci and 208
strains, were examined for their resistance to eighteen antibiotics. The overall resistance (resistance to at least one antibiotic) of these bacteria was 100%. The multiresistance (resistance to at least two antibiotics) of faecal coliforms and faecal streptococci was 94%, whereas 100% of
strains were multiresistant. The monoresistance (resistance to one antibiotic) of faecal coliforms and faecal streptococci strains was 5%, but the monoresistance was not expressed among
strains. Faecal coliforms were most commonly resistant towards sulfamethoxazole (91%), cephalothin (88%) and ampicillin (84%). Faecal streptococci isolates were resistant to polymyxin (87%), to sulfamethoxazole (86%) and to nalidixic acid (85%). The highest prevalence of resistance was noted among
isolates. More than 90% of these strains were resistant to cephalothin (95%), cephotaxim (93%) and polymyxin (92%). The occurrence of faecal pollution bacteria and the presence of high levels of multiple antibiotic resistant bacteria in rural and suburban groundwaters used by local populations, without previous treatment, may have important public health implications.
Authors:Seyedeh Marzieh Jabbari Shiadeh, Leila Azimi, Taher Azimi, Ali Pourmohammad, Mehdi Goudarzi, Bahare Gholami Chaboki, and Ali Hashemi
Antibiotic resistance and especially multiresistance in Enterococci, is a serious public health issue especially in infections of immunocompromised patients. EfrAB is a heterodimeric multidrug ATP-binding cassette (ABC) transporter that causes endogenous resistance to antimicrobials including fluoroquinolones in Enterococcus spp. The aim of this study was to seek the gene expression rate and role of efrAB efflux pump in ciprofloxacin resistant Enterococcus faecalis and Multilocus Sequence Typing (MLST) of multiresistant isolates. Phenotypic and genotyping identification of 80 E. faecalis isolates were performed. Minimum inhibitory concentrations (MICs) to ciprofloxacin (CIP) were measured with and without carbonylcyanide 3-chlorophenylhydrazone (CCCP) by broth microdilution. After DNA extraction and sequencing for detection of efrA and efrB genes, the efrAB efflux positive isolates that were resistant to ciprofloxacin and showed decrease of ciprofloxacin MIC range were identified. Isolates that exhibited decrease in ciprofloxacin MIC range from two to ten folds were assessed for biofilm formation and finally, the expression levels of efrB, efrA genes were measured by quantitative Real-Time PCR (qRT-PCR). High rates of resistance to tetracycline and minocycline and low rates of resistance to the most antibiotics used in this study were detected. The results in this study indicated that the incidence of Multiple drug resistance (MDR) was 23.7% and all isolates that were resistant to ciprofloxacin revealed several degrees of overexpression in efrA and efrB genes. Our study found two ST480 and one ST847 in E. faecalis isolates. In conclusion, despite of low frequency of resistance to the most antibiotics and MDRs in our region, we found one ST480 isolate with resistance to eight antibiotics that also exists in other parts of the world.
Authors:Dolores Cid, José Francisco Fernández-Garayzábal, Chris Pinto, Lucas Domínguez, and Ana Isabel Vela
. A. , Gutierrez , B. , Hidalgo , L. , Garcia , N. , Llagostera , M. , Dominguez , L. and Gonzalez-Zorn , B. ( 2009 ): Multiresistance in Pasteurella multocida is mediated by coexistence of small plasmids . Antimicrob. Agents
Authors:Leila Ben Said, Raoudha Dziri, Nadia Sassi, Carmen Lozano, Karim Ben Slama, Imen Ouzari, Carmen Torres, and Naouel Klibi
Gomez , J. A. , van Schaik , W. , Freitas , A. R. , Coque , T. M. , Weaver , K. E. , Francia , M. V. , Witte , W. and Werner , G. ( 2010 ): Multiresistance megaplasmid pLG1 bearing a hylEfm genomic island in hospital Enterococcus
Authors:Yosra Chebbi, Siwar Frigui, Anis Raddaoui, Dorra Belloumi, Amel Lakhal, Lamia Torjemane, Nour Ben Abeljelil, Saloua Ladeb, Tarek Ben Othmen, Rym El Fatmi, and Wafa Achour
increased by immunosuppression induced by myeloablative chemotherapy as well as by the use of central venous catheters (CVC), essential tool for many treatments prescribed in these patients. CoNS isolates are characterized by their multi-resistance to