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Existen bacterias que se adaptan a diferentes ambientes y hospederos, incluyendo humanos y animales, con los que pueden establecer una relación simbiótica; sin embargo, en condiciones especiales, pueden comportarse como patógenos oportunistas, provocando infecciones que se consideran zoonóticas. Objetivo: Revisar reportes actuales que ponen en evidencia la presencia de las bacterias Staphylococcus aureus y Escherichia coli resistentes a antibióticos en animales de compañía y humanos.Materiales y métodos: Se realizó una búsqueda de literatura en bases de datos de libre acceso y repositorios electrónicos con un periodo de publicación de 2015 a 2022. Resultados: Se describen las características de S. aureus y E. coli que han sido aisladas de mascotas y humanos alrededor del mundo, así como la prevalencia y tasas de resistencia a diferentes grupos de antibióticos. Conclusiones: Los reportes analizados en esta revisión sugieren que el contacto estrecho entre humanos y animales puede favorecer la transmisión bidireccional de bacterias resistentes a los antimicrobianos; por lo que es necesario evaluar medidas desde el punto de vista “Una Salud” para propiciar una sana convivencia basada en la responsabilidad de los dueños, a fin de procurar el bienestar común de los humanos y sus mascotas.

Multidrug-resistant Pseudomonas aeruginosa is one of the main opportunistic pathogens causing severe infection. One of the mechanisms involved in the resistance to imipenem in clinical isolates is the loss of the OprD porin. Changes like substitutions, deletions, insertions, or mutations in the oprD gene can modify the conformation of OprD porin or inhibit its presence and generate resistance to carbapenems. The aim of this work was to obtain anti-OprD polyclonal antibodies and to determine by both immunofluorescence microscopy (IFI) and Western blot assays, the presence of the OprD porin in resistant-carbapenem P. aeruginosa strains with different changes in the oprD gene. Changes in the gene oprD were identified in clinical isolates of P. aeruginosa. When proteins were translated, several polymorphisms were found; however, these did not affect the presence of OprD porin (PCM25, PCM36, and PCM78). Also it was detected an insertion sequence ISPa1328 (PCM52) and a premature stop codon (PCM91), which inhibited the presence of the OprD porin. This study shows how changes in the oprD gene of P. aeruginosa clinical isolates affect the presence of the OprD porin detected by Western blot and indirect immunofluorescence assays using specific polyclonal anti-OprD antibodies generated in this work.

The link between E. coli strains contaminating foods and human disease is unclear, with some reports supporting a direct transmission of pathogenic strains via food and others highlighting their role as reservoirs for resistance and virulence genes. Here we take a genomics approach, analyzing a large set of fully-assembled genomic sequences from E. coli available in GenBank. Most of the strains isolated in food are more closely related to each other than to clinical strains, arguing against a frequent direct transmission of pathogenic strains from food to the clinic. We also provide strong evidence of genetic exchanges between food and clinical strains that are facilitated by plasmids. This is based on an overlapped representation of virulence and resistance genes in plasmids isolated from these two sources. We identify clusters of phylogenetically-related plasmids that are largely responsible for the observed overlap and see evidence of specialization, with some food plasmid clusters preferentially transferring virulence factors over resistance genes. Consistent with these observations, food plasmids have a high mobilization potential based on their plasmid taxonomic unit classification and on an analysis of mobilization gene content. We report antibiotic resistance genes of high clinical relevance and their specific incompatibility group associations. Finally, we also report a striking enrichment for adhesins in food plasmids and their association with specific IncF replicon subtypes. The identification of food plasmids with specific markers (Inc and PTU combinations) as mediators of horizontal transfer between food and clinical strains opens new research avenues and should assist with the design of surveillance strategies.

Objectives The aim of this study was to identify Acinetobacter spp. strains from paediatric patients, to determine their genetic relationship, to detect antibiotic resistance genes and to evaluate the role of efflux pumps in antibiotic resistance. Methods A total of 54 non-duplicate, non-consecutive Acinetobacter spp. isolates were collected from paediatric patients. Their genetic relationship, antibiotic resistance profile, efflux pump activity, antibiotic resistance genes and plasmid profile were determined. Results The isolates were identified as 24 Acinetobacter haemolyticus, 24 Acinetobacter calcoaceticus–baumannii (Acb) complex and 1 strain each of Acinetobacter junii, Acinetobacter radioresistens, Acinetobacter indicus, Acinetobacter lwoffii, Acinetobacter ursingii and Acinetobacter venetianus. The 24 A. haemolyticus were considered genetically unrelated. One strain was resistant to carbapenems, two to cephalosporins, two to ciprofloxacin and sixteen to aminoglycosides. The antibiotic resistance genes blaOXA-214 (29%), blaOXA-215 (4%), blaOXA-264 (8%), blaOXA-265 (29%), blaNDM-1 (4%), aac(6ʹ)-Ig (38%) and the novel variants blaOXA-575 (13%), blaTEM-229 (75%), aac(6ʹ)-Iga (4%), aac(6ʹ)-Igb (13%) and aac(6ʹ)-Igc (42%) were detected. Among 24 Acb complex, 5 were multidrug-resistant, carbapenem-resistant strains carrying blaOXA-51 and blaOXA-23; they were genetically related and had the same plasmid profile. Other species were susceptible. In some strains of A. haemolyticus and Acb complex, the role of RND efflux pumps was evidenced by a decrease in the MICs for cefotaxime, amikacin and ciprofloxacin in the presence of an efflux pump inhibitor. Conclusions This study identified isolates of A. haemolyticus carrying new β-lactamase variants and shows for the first time the contribution of efflux pumps to antibiotic resistance in this species.

Haemophilus influenzae is the causal agent of invasive pediatric diseases, such as meningitis, epiglottitis, pneumonia, septic arthritis, pericarditis, cellulitis, and bacteremia (serotype b). Non-typeable H. influenzae (NTHi) strains are associated with localized infections, such as otitis media, conjunctivitis, sinusitis, bronchitis, and pneumonia, and can cause invasive diseases, such as as meningitis and sepsis in immunocompromised hosts. Enolase is a multifunctional protein and can act as a receptor for plasminogen, promoting its activation to plasmin, which leads to the degradation of components of the extracellular matrix, favoring host tissue invasion. In this study, using molecular docking, three important residues involved in plasminogen interaction through the plasminogen-binding motif (251EFYNKENGMYE262) were identified in non-typeable H. influenzae enolase (NTHiENO). Interaction with the human plasminogen kringle domains is conformationally stable due to the formation of four hydrogen bonds corresponding to enoTYR253-plgGLU1 (K2), enoTYR253-plgGLY310 (K3), and enoLYS255-plgARG471/enoGLU251-plgLYS468 (K5). On the other hand, in vitro assays, such as ELISA and far-western blot, showed that NTHiENO is a plasminogen-binding protein. The inhibition of this interaction using polyclonal anti-NTHiENO antibodies was significant. With these results, we can propose that NTHiENO–plasminogen interaction could be one of the mechanisms used by H. influenzae to adhere to and invade host cells.

Background/purpose Uropathogenic E. coli (UPEC) is the main cause of urinary tract infection (UTI) and it is known that pregnant women have a higher risk for UTI. UPEC has a variety of virulence and antibiotic resistance factors that facilitate its pathogenic success and it is crucial to know which are the susceptibility patterns, Extended-Spectrum-β-Lactamase (ESBL) production, virulence genes, pathogenicity islands (PAI), phylogenetic groups and serotypes among strains isolated from pregnant and non-pregnant women. Methods One hundred fifty UPEC strains were isolated from pregnant and non-pregnant women from two different Mexican states (Sonora and Puebla). Strains were analyzed using the Kirby-Bauer method for the determination of antibiotic susceptibility and ESBL. Virulence genes, PAIs and phylogenetic groups were determined using a multiplex PCR. Strains were serotyped by an agglutination assay. Blood agar and CAS agar were used for phenotypic assays. Results 92.7% of UPEC strains showed multidrug-resistant (MDR), 6.7% extremely-resistant (XDR) and 0.6% pandrug-resistant (PDR). The highest resistance was determined to be for β-lactam antibiotics (>72% in both states) and 44.5% of the UPEC strains were ESBL+. The predominant virulence genes found were fimH (100%), iucD (85%) and iha (60%). The strains isolated from pregnant women from Puebla presented a large percentage of genes associated with upper urinary tract infections. PAIs were found in 51% and 68% of the strains from Sonora and Puebla, respectively. All the strains were siderophores producers and 41.5% produced hemolysis. The serotypes found were diverse and belonged to phylogroups A, B2 and C. Conclusion The UPEC strains from this study are MDR with tendency to XDR or PDR, they can cause upper UTIs and are serotypically and phylogenetically diverse, which supports the need to develop new strategies for UTI treatment in pregnant and non-pregnant Mexican women.

Introduction: The emergence of extended-spectrum β-lactamases (ESBLs)-producing Escherichia coli clones are a public health concern worldwide. Scarce information does exist about the spread of ESBLs-producing E. coli in pediatric patients from developing countries. Methodology: E. coli strains were analyzed by multilocus-sequence-typing, pulsed-field-gel-electrophoresis and phylogenetic group. The antimicrobial-resistance genes were detected by PCR, and plasmid content by the PCR-based replicon-typing. Horizontal transfer was tested by conjugation and the location of the blaCTX-M-15 gene by Southern blot hybridization. Results: Thirty-two cefotaxime-resistant E. coli were recovered. Eleven of them were ESBL-producing isolates, which were well characterized and ascribed to seven sequence types and five phylogroups. The ESBL CTX-M-15 was the most prevalent enzyme (9 of 11). Plasmids of variable sizes (40-220 kb) were visualized, and the incompatibility (Inc) group FIB plasmid-replicon was detected in the ESBL strains and transferred by conjugation in 45.45% of them. Plasmid-borne toxin-antitoxin systems were the most frequently detected systems, strongly associated to IncF plasmids. The CTX-M-15-encoding gene was located on IncFIB plasmids. Conclusions: Even though a small number of ESBL-producing strains was recovered, we evidenced that IncFIB plasmids carry the blaCTX-M-15 gene, highlighting the role of IncF-type plasmids in facilitating the spread and maintenance of ESBL-encoding genes, which further favors the rapid increase of the antimicrobial resistance dissemination in disease-causing E. coli strains in pediatric patients.

Haemophilus influenzae is a common organism of the human upper respiratory tract; this bacterium is responsible of a wide spectrum for respiratory infections and can generate invasive diseases such as meningitis and septicemia. These infections are associated with H. influenzae encapsulated serotype b. However, the incidence of invasive disease caused by nontypeable H. influenzae (NTHi) has increased in the post-H. influenzae serotype b (Hib) vaccine era. Currently, an effective vaccine against NTHi is not available; due to this, it is important to find an antigen capable to confer protection against NTHi infection. In this study, 10 linear B cell epitopes and 13 CTL epitopes and a putative plasminogen-binding motif (252FYNKENGMY260) and the presence of enolase on the surface of different strains of H. influenzae were identified in the enolase sequence of H. influenzae. Both in silico and experimental results showed that recombinant enolase from H. influenzae is immunogenic that could induce a humoral immune response; this was observed mediating the generation of specific polyclonal antibodies anti-rNTHiENO that recognize typeable and nontypeable H. influenzae strains. The immunogenic properties and the superficial localization of enolase in H. influenzae, important characteristics to be considered as a new candidate for the development of a vaccine, were demonstrated.

Purpose: Pseudomonas aeruginosa infections in hospitals constitute an important problem due to the increasing multidrug resistance (MDR) and carbapenems resistance. The knowledge of resistance mechanisms in Pseudomonas strains is an important issue for an adequate antimicrobial treatment. Therefore, the objective was to investigate other antimicrobial resistance mechanisms in MDR P. aeruginosa strains carrying bla IMP , make a partial plasmids characterization, and determine if modifications in oprD gene affect the expression of the OprD protein. Methodology: Susceptibility testing was performed by Kirby Bauer and by Minimum Inhibitory Concentration (presence/absence of efflux pump inhibitor); molecular typing by Pulsed-field gel electrophoresis (PFGE), resistance genotyping and integrons by PCR and sequencing; OprD expression by Western blot; plasmid characterization by MOB Typing Technique, molecular size by PFGE-S1; and bla location by Southern blot. IMP Results: Among the 59 studied P. aeruginosa isolates, 41 multidrug resistance and carbapenems resistance isolates were detected and classified in 38 different PFGE patterns. Thirteen strains carried bla IMP; 16 bla GES and four carried both genes. This study centered on the 17 strains harboring bla IMP . New variants of β-lactamases were identified (bla GES-32, bla IMP-56, bla IMP-62 ) inside of new arrangements of class 1 integrons. The presence of bla IMP gene was detected in two plasmids in the same strain. The participation of the OprD protein and efflux pumps in the resistance to carbapenems and quinolones is shown. No expression of the porin OprD due to stop codon or IS in the gene was found. Conclusions: This study shows the participation of different resistance mechanisms, which are reflected in the levels of MIC to carbapenems. This is the first report of the presence of three new variants of β-lactamases inside of new arrangements of class 1 integrons, as well as the presence of two plasmids carrying bla IMP in the same P. aeruginosa strain isolated in a Mexican hospital.

Purpose Broad-spectrum cephalosporin resistance is rapidly increasing in Escherichia coli, representing a food safety problem. The purpose of this paper is to characterize eight extended-spectrum-ß-lactamase (ESBL) and acquired AmpC ß-lactamase-producing E. coli isolates and virotypes associated, obtained from chicken and pork food samples in Puebla, Mexico. Design/methodology/approach Samples (36 from chicken and 10 from pork) were cultured on Levine agar plates supplemented with cefotaxime (2 mg/L) for isolation of cefotaxime-resistant (CTXR) E. coli. CTXR-E. coli isolates were detected in 33 of 46 samples (72 percent), and one isolate/sample was characterized (28 from chicken and 5 from pork), for ESBL production, phylogenetic group, sequence typing, resistance and virulence genes by PCR and sequencing. Findings Results showed 16 ESBL-E. coli (35 percent) (12/16 belonging to phylogroup B1) and 8 CMY-2-E. coli (17 percent). ESBL detected were as follows (number of isolates): CTX-M-2 (8); CTX-M-1 (2); CTX-M-15 (1); SHV-2a (4) and TEM-52c (1). In total, 20 different sequence types (STs) were identified among the ESBL- or CMY-2-producing E. coli strains, which included four new ones. The CTX-M-15 β-lactamase was detected in one E. coli ST617-ST10 Cplx-B1 strain that also carried ibeA gene. One CMY-2-positive strain of lineage ST224-B2 was detected and it carried the qnrA1 gene. Originality/value In this study, a ST131-based virotyping scheme for strains from food of animal origin was established since this kind of strains constitutes an important vehicle of virulent ESBL- and CMY-2-producing E. coli isolates, which could be transmitted to humans by direct contact or through the food chain.

Ninety-six methicillin-susceptible Staphylococcus aureus (MSSA) and 11 methicillin-resistant coagulase-negative staphylococci (MRCNS) were recovered from food of animal origin. Multi-drug resistance was detected in 34.1% of isolates. Tetracycline-resistant staphylococci harbored tetK gene (68.8%). Erythromycin/clindamycin-resistant staphylococci carried lnuA/lnuB genes frequently alone or combined with msrA gene. The sec gene was detected in 15.6% of MSSA and two isolates harbored the immune evasion cluster. The spa t337 predominated among MSSA strains. Two ermC-positive MRCNS isolates were observed, five mecA-positive carried SCCmec IVa and 6 were non-typeable by the IWG-SCC classification. These results demonstrate that food of animal origin can be a potential source for spreading of multidrug-resistance gene.

Purpose. Haemophilus influenzae is a commensal organism found in the upper respiratory tract of humans. When H. influenzae becomes a pathogen, these bacteria can move out of their commensal niche and cause multiple respiratory tract diseases such as otitis media, sinusitis, conjunctivitis and bronchitis in children, and chronic obstructive pulmonary disease in adults. However, H. influenzae is currently considered a non-flagellate bacterium. Methodology and Results. In this study, 90 clinical isolates of H. influenzae strains (typeable and non-typeable) showed different degrees of the swarm-motility phenotype in vitro. Keys findings. One of these strains, NTHi BUAP96, showed the highest motility rate and its flagella were revealed using transmission electron microscopy and Ryu staining. Moreover, the flagellar genes fliC and flgH exhibited high homology with those of Actinobacillus pleuropneumoniae, Escherichia coli and Shigella flexneri. Furthermore, Western blot analysis, using anti-flagellin heterologous antibodies from E. coli, demonstrated cross-reaction with a protein present in NTHi BUAP96. Conclusion. This study provides, for the first time, information on flagellar expression in H. influenzae, representing an important finding related to its evolution and pathogenic potential.

Acinetobacter calcoaceticus-baumannii complex isolates have been frequently associated with hospital and community infections, with A. baumannii being the most common. Other Acinetobacter spp. not belonging to this complex also cause infections in hospital settings, and the incidence has increased over the past few years. Some species of the Acinetobacter genus possess a great diversity of antibiotic resistance mechanisms, such as efflux pumps, porins, and resistance genes that can be acquired and disseminated by mobilizable genetic elements. By means of whole-genome sequencing, we describe in the clinical Acinetobacter haemolyticus strain AN54 different mechanisms of resistance that involve blaOXA-265, blaNDM-1, aphA6, aac(6’)-Ig, and a resistance-nodulation-cell division-type efflux pump. This strain carries six plasmids, of which the plasmid pAhaeAN54e contains blaNDM-1 in a Tn125-like transposon that is truncated at the 3′ end. This strain also has an insertion sequence IS91 and seven genes encoding hypothetical proteins. The pAhaeAN54e plasmid is nontypable and different from other plasmids carrying blaNDM-1 that have been reported in Mexico and other countries. The presence of these kinds of plasmids in an opportunistic pathogen such as A. haemolyticus highlights the role that these plasmids play in the dissemination of antibiotic resistance genes, especially against carbapenems, in Mexican hospitals.

Multidrug-resistant bacteria are a growing problem in different environments and hosts, but scarce information exists about their prevalence in reptiles. The aim of this study was to analyze the resistance mechanisms, molecular typing, and plasmid content of cefotaxime-resistant (CTX(R)) Escherichia coli isolates recovered from cloacal samples of 71 turtles sheltered in a herpetarium in Mexico. CTX(R)-E. coli were recovered in 11 of 71 samples (15.5%), and one isolate/sample was characterized. Extended-spectrum β-lactamase (ESBL)-producing E. coli isolates were detected in four samples (5.6%): two strains carried the blaCTX-M-2 gene (phylogroup D and ST2732) and two contained the blaCTX-M-15 gene (phylogroup B1 and lineages ST58 and ST156). The blaCMY-2 gene was detected by PCR in E. coli isolates of eight samples (9.8%) (one of them also carried blaCTX-M-2); these isolates were distributed into phylogroups A (n = 1), B1 (n = 6), and D (n = 1) and typed as ST155, ST156, ST2329, and ST2732. Plasmid-mediated quinolone resistance (PMQR) genes were detected in five isolates [aac(6')Ib-cr, qnrA, qnrB19, and oqxB]. From three to five replicon plasmids were detected among the strains, being IncFIB, IncI1, IncFrep, and IncK the most prevalent. ESBL or pAmpC genes were transferred by conjugation in four strains, and the blaCTX-M-15 and blaCMY-2 genes were localized in IncFIB or IncI1 plasmids by Southern blot hybridization assays. Class 1 and/or class 2 integrons were detected in eight strains with six different structures of gene cassette arrays. Nine pulsed-field gel electrophoresis patterns were found among the 11 studied strains. To our knowledge, this is the first detection of ESBL, CMY-2, PMQR, and mobile determinants of antimicrobial resistance in E. coli of turtle origin, highlighting the potential dissemination of multidrug-resistant bacteria from these animals to other environments and hosts, including humans.

A practical method to determine Staphylococcus aureus using bioconjugated gold nanoparticles is reported. The protocol uses gold nanoparticles stabilized by tetramethylrhodamine isothiocyanate labeled streptavidin followed by functionalization with biotinylated anti-staphylococcus aureus antibodies. The streptavidin stabilized gold nanoparticles were obtained by titration and analyzed by ultraviolet-visible spectroscopy and transmission electron microscopy. The obtained fluorescent bioconjugate selectively linked to the surface of S. aureus in samples contaminated with the microorganism, as demonstrated by confocal micrographs. The biorecognition process was performed by mixing the fluorescent bioconjugate with the sample. Bacterial dilutions from 1 × 108 to 1 × 102 cell/ml of S. aureus were determined, obtaining sensitivity values of 1 × 105 cell/ml by photoluminescence and 1 × 102 cell/ml by bioimpedance. This methodology represents a useful bioanalytical approach for the determination of Staphy...

Acinetobacter calcoaceticus-baumannii complex isolates have been frequently associated with hospital and community infections, with A. baumannii being the most common. Other Acinetobacter spp. not ...

Background The widespread Escherichia coli clone ST131 implicated in multidrug-resistant infections has been recently reported, the majority belonging to O25:H4 serotype and classified into five main virotypes in accordance with the virulence genes carried. Methods Pathogenicity Islands I and II (PAI-I and PAI-II) were determined using conventional PCR protocols from a set of four E. coli CTXR ST131 O25:H4/H30-Rx strains collected from healthy donors’ stool. The virulence genes patterns were also analyzed and compared them with the virotypes reported previously; then adherence, invasion, macrophage survival and biofilm formation assays were evaluated and AIEC pathotype genetic determinants were investigated. Findings Non-reported virulence patterns were found in our isolates, two of them carried satA, papA, papGII genes and the two-remaining isolates carried cnfI, iroN, satA, papA, papGII genes, and none of them belonged to classical ST131 virotypes, suggesting an endemic distribution of virulence genes and two new virotypes. The presence of PAI-I and PAI-II of Uropathogenic E. coli was determined in three of the four strains, furthermore adherence and invasion assays demonstrated higher degrees of attachment/invasion compared with the control strains. We also amplified intI1, insA and insB genes in all four samples. Interpretation The results indicate that these strains own non-reported virotypes suggesting endemic distribution of virulence genes, our four strains also belong to an AIEC pathotype, being this the first report of AIEC in México and the association of AIEC with healthy donors.

Purpose Pseudomonas aeruginosa infections in hospitals constitute an important problem due to the increasing multidrug resistance (MDR) and carbapenems resistance. The knowledge of resistance mechanisms in Pseudomonas strains is an important issue for an adequate antimicrobial treatment. Therefore, the objective was to investigate other antimicrobial resistance mechanisms in MDR P. aeruginosa strains carrying blaIMP, make a partial plasmids characterization, and determine if modifications in oprD gene affect the expression of the OprD protein. Methodology Susceptibility testing was performed by Kirby Baüer and by Minimum Inhibitory Concentration (presence/absence of efflux pump inhibitor); molecular typing by Pulsed-field gel electrophoresis (PFGE), resistance genotyping and integrons by PCR and sequencing; OprD expression by Western blot; plasmid characterization by MOB Typing Technique, molecular size by PFGE-S1; and blaIMP location by Southern blot. Results Among the 59 studied P. aeruginosa isolates, 41 multidrug resistance and carbapenems resistance isolates were detected and classified in 38 different PFGE patterns. Thirteen strains carried blaIMP; 16 blaGES and four carried both genes. This study centered on the 17 strains har-boring blaIMP. New variants of β-lactamases were identified (blaGES-32, blaIMP-56, blaIMP-62) inside of new arrangements of class 1 integrons. The presence of blaIMP gene was detected in two plasmids in the same strain. The participation of the OprD protein and efflux pumps in the resistance to carbapenems and quinolones is shown. No expression of the porin OprD due to stop codon or IS in the gene was found. Conclusions This study shows the participation of different resistance mechanisms, which are reflected in the levels of MIC to carbapenems. This is the first report of the presence of three new variants of β-lactamases inside of new arrangements of class 1 integrons, as well as the presence of two plasmids carrying blaIMP in the same P. aeruginosa strain isolated in a Mexican hospital.

Integrons are genetic platforms able to excise, integrate and express antibiotic resistance gene cassettes (GCs). Here we investigated the complete genetic organisation, genetic environment, location and conjugative transferability of a collection of class 2 integrons carried by Escherichia coli strains from different sources (poultry/pork meat, animals and humans). PCR cartography was conducted to determine the genetic arrangement of the integrons, their physical linkage to Tn7 and chromosomal insertion at the attTn7 site. Clonal relatedness of specific isolates was determined by MLST and DO-PCR. Transferability of class 2 integrons was tested by conjugation. The resulting transconjugants were characterised by antimicrobial resistance genotyping, S1-PFGE and replicon typing. Although a limited diversity of GCs was shown, a high percentage of novel structures was identified owing to the integration of insertion sequence (IS) elements at different sites (IS3/IS4/IS5/IS21 families). Insertion of IS10 in the attI2 site of a class 2 integron, between Pc2B and Pc2C promoters, was likely mediated by a site-specific transposition event. Chromosomal insertion of integrons at attTn7 was confirmed in 80% of the isolates. Conjugation experiments demonstrated that 29% of class 2 integrons could be mobilised to E. coli CHS26, demonstrating that they can be located in conjugative/mobilisable elements at a low frequency. Reported structures evidence how class 2 integrons have evolved by the activity of integron integrases and the invasion of ISs. Since most of them are chromosomally located, dispersion is predominantly vertical, although conjugation events also contribute to the spread of class 2 integrons among bacterial communities. Fil: Alonso, Carla Andrea. Universidad de la Rioja; España Fil: Cortés Cortés, Gerardo. Benemérita Universidad Autónoma de Puebla; México Fil: Maamar, Elaa. University Of Tunis El Manar; Túnez Fil: Masso, Mariana Guillermina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; Argentina Fil: Rocha Gracia, Rosa del Carmen. Benemérita Universidad Autónoma de Puebla; México Fil: Torres, Carmen. Universidad de la Rioja; España Fil: Centron, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; Argentina Fil: Quiroga, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; Argentina

The presence of extended spectrum β-lactamase (ESBL) and plasmid-mediated AmpC β-lactamase (pAmpC) producing Escherichia coli, along with the mechanisms of antimicrobial resistance and the molecular types of isolates, was investigated in faecal samples from 53 healthy dogs in Mexico. Samples were inoculated on Levine agar plates with 2 µg/mL cefotaxime for recovery of cefotaxime-resistant (CTX(R)) E. coli. CTX(R)E. coli isolates were recovered from 9/53 (17%) samples; one isolate was characterised from each positive sample. ESBL producing E. coli isolates were detected in 3/53 (6%) samples; these isolates carried the blaCTX-M-15 gene and one isolate also carried blaSHV-2. These three ESBL-positive E. coli isolates belonged to phylogroup A and sequence types ST617, ST410 or ST3944. The remaining 6/53 (11%) samples contained pAmpC positive isolates; these isolates carried the blaCMY-2 gene, which encodes CMY-2 β-lactamase. These six isolates belonged to phylogroups A (n = 2), B1 (n = 1) and D (n = 3), and sequences types ST1431, ST57, ST93 and ST4565. One CMY-2 β-lactamase positive E. coli isolate of lineage ST93 had the -32 mutation in the chromosomal ampC promoter/attenuator region. Five ESBL/pAmpC positive E. coli isolates carried class 1 integrons (dfrA17-aadA5, aadA and aadA/aadB arrays were detected in three isolates) and one isolate carried a class 2 integron (dfrA12-sat2-aadA1). The aac(6')Ib-cr, aac(3)-II, qnrB19, tet(A), tet(B), cmlA, and sul3 genes were also detected. All studied isolates showed unrelated PFGE-patterns. To our knowledge, this is the first description of ESBL-producing E. coli and the second of pAmpC-producing E. coli from healthy dogs in America. Our results suggest the potential zoonotic role of dogs in the transmission to humans of ESBL and pAmpC E. coli in the household environment.

The Authors regret that one of the Authors, Maria Paula Quiroga, was erroneously not tagged as a corresponding Author. The authors would like to apologise for any inconvenience caused.

Objectives The resistance mechanisms, molecular type and plasmid content of cefotaxime-resistant Escherichia coli isolated from faecal samples of healthy volunteers in Puebla, Mexico, were characterised. Methods and results Cefotaxime-resistant E. coli were recovered from 11 (18%) of 60 healthy volunteers. The isolates (one per sample) were characterised as multidrug-resistant and phenotypically extended-spectrum β-lactamase (ESBL)-producing strains. Genes encoding resistance to β-lactams (blaCTX-M-15, blaCTX-M-14a, blaCTX-M-14b, blaOXA-1, blaTEM-1b), quinolones [aac(6′)-Ib-cr, qnrB19], aminoglycosides [aac(3′)-II] and tetracycline [tet(A), tet(B)] were detected among the 11 ESBL-producing E. coli by PCR and sequencing, as well as gene cassette arrays in class 1 (dfrA17–aadA5) and class 2 (dfrA1–sat2–aadA1) integrons. Seven pulsotypes were identified by XbaI PFGE and the strains were distributed into phylogroups (number of isolates) A (2), B2 (4) and D (5). Seven sequence types were identified, four of them novel (ST5060, ST5079, ST5080 and ST5081), associated with phylogroups A–D. Transfer of a 140-kb IncFIA plasmid carrying the blaCTX-M-15 gene was evidenced in the ST5060 strain. Four CTX-M-15-producing E. coli strains of phylogroup B2 belonged to the ST131 complex, and IncFIB plasmids of 130 kb and 155 kb were detected in two of them. Multiple plasmid addiction systems were also found. Serotyping and fimH subtyping of ST131-B2 strains identified the ST131-B2-O25:H4-H30-Rx subclone. Additionally, this subclone and CTX-M-14-producing isolates were detected among residents living in the same household, suggesting clonal dissemination. Conclusions This study reports the detection of E. coli ST131-B2-O25:H4-H30-Rx subclone in healthy humans in Mexico, highlighting its dissemination in the community setting.

Objectives: To characterize the location and genetic environments of qnr, aac(6')-Ib-cr and qepA genes related to quinolone resistance in 19 Escherichia coli, Klebsiella pneumoniae and Klebsiella oxytoca strains. Methods: Genetic environments of the indicated genes were studied by cloning, PCR mapping and sequencing. The location of these genes was analysed by S1-PFGE and PFGE-I-CeuI and hybridization with specific probes. Associated antibiotic resistance mechanisms and molecular typing of strains were also investigated. Results: The studied strains carried the aac(6')-Ib-cr, qepA, qnrS1, qnrB6, qnrB4 and oqxAB genes, with aac(6')-Ib-cr being the most prevalent. E. coli strains belonged to sequence types (STs) ST648, ST131, ST224 and ST205, and K. pneumoniae strains to ST433, ST341, ST152, ST15 and ST431. Different genetic environments of quinolone resistance genes were observed, and some of them had not been previously detected and registered in GenBank. The aac(6')-Ib-cr gene was mainly located in class 1 integrons or associated with the Tn1721 transposon in E. coli and associated with the aac(3)-II gene in Klebsiella. All these structures contained mechanisms of gene acquisition and/or dissemination, such as IS26. The studied quinolone resistance genes were mostly detected in IncF and IncN plasmids in E. coli and in IncR plasmids in Klebsiella, but in some strains the chromosomal location of the aac(6')-Ib-cr gene was detected for the first time. The bla CTX-M-15, bla OXA-1, tet(A), aac(3)-II and aph(3')-Ia genes and class 1 integrons were found in most strains. Conclusions: The aac(6')-Ib-cr gene was detected for the first time in the chromosome, although a plasmidic location was the most frequently found, with differentiation of plasmids types in E. coli versus Klebsiella. © The Author 2012. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

An outbreak due to a Klebsiella pneumoniae clone occurred in a neonatal intensive care unit of a Spanish Hospital in which three newborns were infected (all with gestational age ≤29 weeks; two of them died) and seven were colonized (gestational age32 weeks; none died). One K. pneumoniae strain per patient was further characterized. The 10 strains showed an indistinguishable pulsed-field-gel-electrophoresis pattern, were typed in the phylogenetic group KpI and were ascribed into a new sequence type registered as ST341. All 10 strains presented the same multiple-antibiotic-resistant phenotype, showed extended-spectrum-beta-lactamase production, and harbored the bla(CTX-M-15), bla(SHV-11), bla(OXA-1,)aac(6')-Ib-cr, qnrS1, aac(3)-II, aph(3')-Ia and aadA5 resistance genes. No class 1 or class 2 integrons were detected. The bla(CTX-M-15) gene presented the following genetic environment: ISEcp1-bla(CTX-M-15)-orf477. These strains contained two copies of the aac(6')-Ib-cr gene included in the following new genetic environments: aac(3)-II-IS26-aac(6')-Ib-cr-bla(OXA-1) and aac(3)-II-IS26-ΔcatB3-bla(OXA-1)-aac(6')-Ib-cr (registered at GenBank with accession numbers GQ438247 and GQ438248, respectively). The genetic environment of the qnrS1 gene (IS26-ΔISEcl2-qnrS1) (GenBank accession number GQ438249) was also not described previously. The aac(6')-Ib-cr, qnrS1, bla(CTX-M-15), aac(3)-II, and bla(OXA-1) genes, located in a plasmid of 33.5 kb, could be transferred to Escherichia coli by transformation.

Hormones play a significant role in murine Taenia crassiceps cysticercosis, and they may also participate in the susceptibility to Taenia solium cysticercosis. In the present study, in vitro effects are reported for human chorionic gonadotropin (hCG) on the larval stages of T. crassiceps (WFU strain) and T. solium. Our results reveal the presence of receptors for hCG in different developmental phases of both cultured parasites. On day 30, both taeniid species had the highest percentage of receptors in the neck, strobila, and suckers, but these receptors decreased by day 60, delimiting the segments and the exterior of the developing proglottids in T. solium. At the same time, there was a large number of hCG receptors in the area of the presumptive cirrus organ and in calcareous corpuscles within the parenchyma. This is the first report detecting receptors for hCG on different larval stages of T. crassiceps and T. solium. A direct effect of hCG could be recognized by the cysticerci as a factor contributing to the growth and development of T. crassiceps and T. solium cysticerci, respectively.

The genus Klebsiella belongs to the family Enterobacteriaceae, and is currently considered to be non-motile and non-flagellated. In the present work, 25 Klebsiella strains isolated from nosocomial infections were assessed for motility under different growth conditions. One Klebsiella isolate, KpBUAP021, demonstrated a swim-like motility phenotype. The K. pneumoniae genotype was confirmed by 16S rRNA and rpoB gene sequence analysis. Multilocus sequence typing analysis also revealed that the KpBUAP021 strain places it in the ST345 sequence type, and belongs to the phylogenetic Kpl group. Transmission electron microscopy and the Ryu staining technique revealed that KpBUAP021 expresses polar flagella. Finally, the presence of fliC, fliA and flgH genes in this K. pneumoniae strain was confirmed. This report presents the first evidence for flagella-mediated motility in a K. pneumoniae clinical isolate, and represents an important finding related to its evolution and pathogenic potential. © 2016 The Authors.

We report that Brucella abortus and Brucella melitensis agglutinate human (A+ and B+), hamster and rabbit erythrocytes, a heretofore undescribed feature in this genus. This activity was associated with a 29-kDa surface protein (SP29) that bound selectively to these erythrocytes and this binding was inhibited by rabbit anti-SP29 antibodies. Hemagglutination was inhibited by pretreatment of erythrocytes with neuraminidase and by preincubation of B. abortus with chondroitin sulfate, N-acetylneuraminic acid and N-acetylneuramin-lactose.

Associating high morbid-mortality with sepsis makes it necessary to have a rapid detection and identification of the causal microorganism. The objective of this study is on the standardization and use of the nested-polymerase chain reaction (PCR) method for the differentiation of Gram-positive and Gram-negative bacteria in patients with sepsis-septic shock. PCR, using whole blood from clinically healthy individuals with various concentrations of bacterial DNA (0.5 pg to 0.5 ng) from Gram-positive and Gram-negative bacteria was standardized. Additionally, the method was assayed in patients from Pediatric Intensive Care Unit (PICU) and Intensive Care Unit (ICU) of the University Hospital in Puebla, Mexico. Samples were drawn from 10 adults (25 samples) and 21 children (40 samples) diagnosed with sepsis. Each sample was assayed by nested-PCR and blood culture. Nested-PCR sensitivity results were different among bacterial DNAs assayed. The nested-PCR was positive (89%) in samples from patients with a positive blood culture. The nested-PCR was also positive (12%) in samples with negative blood culture, but with a documented sepsis. Nested-PCR described here needs additional confirmation as a diagnostic tool of sepsis. This method, which uses whole blood, could be an additional auxiliary in combination with blood culture for the early diagnosis and the selection of a specific antimicrobial therapy against sepsis. Key words: Sepsis-septic shock, nested- polymerase chain reaction (PCR), sepsis diagnosis.

Centro de Investigaciones en Ciencias Microbiologicas, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla (BUAP), Puebla, Mexico; Area Bioquimica y Biologia Molecular, Universidad de La Rioja, Logrono, Spain; Facultad de Medicina, licenciatura en Biomedicina, BUAP, Puebla, Mexico; Laboratorio de Analisis Clinicos Ehrlich, Puebla, Mexico; Hospital Universitario, BUAP, Puebla, Mexico

Background Interferon (IFN)-α receptor 1 (ifnar1) and suppressor of cytokine signaling 1 (socs1) transcription levels were quantified in peripheral blood mononuclear cells (PBMC) of 59 patients infected with hepatitis C virus (HCV) and 17 non-infected individuals. Samples were obtained from patients infected with HCV that were either untreated or treated with IFN-α2 plus ribavirin for 1 year and divided into responders and non-responders based on viral load reduction 6 months after treatment. Ifnar1 and socs1 transcription was quantified by real-time RT-PCR, and the fold difference (2-ΔΔCT) with respect to hprt housekeeping gene was calculated. Results Ifnar1 transcription increased significantly in HCV-infected patients either untreated (3.26 ± 0.31), responders (3.1 ± 0.23) and non-responders (2.18 ± 0.23) with respect to non-infected individuals (1 ± 0.34; P = 0.005). Ifnar1 transcription increased significantly (P = 0.003) in patients infected with HCV genotypes 1a (4.74 ± 0.25) and 1b (2.81 ± 0.25) but not in 1a1b (1.58 ± 0.21). No association was found of Ifnar1 transcription with disease progress, initial viral load or other clinical factors. With respect to socs1 transcription, values were similar for non-infected individuals (1 ± 0.28) and untreated patients (0.99 ± 0.41) but increased in responders (2.81 ± 0.17) and non-responder patients (1.67 ± 0.41). Difference between responder and non-responder patients was not statistically significant. Socs1 transcription increased in patients infected with HCV genotypes 1a and 1b (2.87 ± 0.45 and 2.22 ± 0.17, respectively) but not in 1a1b (1.28 ± 0.40). Socs1 transcript was absent in three patients infected with HCV genotype 1b. A weak correlation between ifnar1 and socs1 transcription was found, when Spearman's correlation coefficient was calculated. Conclusion Our results suggest that HCV infection may up-regulate ifnar1 transcription. HCV genotypes differ in their capacity to affect ifnar1 and socs1 transcription, as well as in the ability to evade the antiviral response.