Evidence for convergent evolution of CTX-M-14 ESBL in Escherichia coli and its prevalence.

A total of 2440 Escherichia coli strains isolated in 2003 at the Hospital de la Santa Creu i Sant Pau were evaluated for the presence of extended-spectrum beta-lactamases. Two different nucleotide sequences that encode the same beta-lactamase, CTX-M-14, were detected when the bla(CTX-M-14)-genes of 35 E. coli isolates were analysed. Thirty-two of the 35 had the previously described sequence of the bla(CTX-M-14) (AF252622), named bla(CTX-M-14a), and the remaining three isolates showed a nucleotide sequence identical to that of the bla(CTX-M-9) gene except for one nucleotide, named bla(CTX-M-14b). Characterisation of the regions surrounding the bla(CTX-M-14a) showed the ISEcp1 and the IS903 upstream and downstream, respectively, of the bla gene, whereas the regions surrounding the bla(CTX-M-14b) contained the genetic environment described for the bla(CTX-M-9) gene, the In60. Characterisation by hybridisation showed that the bla(CTX-M-14a) was present in IncK plasmids, whereas the bla(CTX-M-14b) was found in the HI2 Inc group. The CTX-M-14 ESBL in E. coli isolates is the result of the convergence of two different genes.

ESBL- and plasmidic class C beta-lactamase-producing E. coli strains isolated from poultry, pig and rabbit farms.

This study aims to determine the presence of extended-spectrum (ESBL) and plasmidic class C beta-lactamase-producing Enterobacteriaceae in poultry, pig and rabbit farms of Catalonia (Spain). PFGE typing showed a low clonal relationship among strains carrying these mechanisms of resistance. Ninety-three percent of them were resistant to two or more of the non-beta-lactam antimicrobials tested and harboured ESBL and plasmidic class C beta-lactamases. Greater diversity of these enzymes was found in strains from poultry farms, the CTX-M-9 family, especially CTX-M-14, with CMY-2 being the most frequent. The isolation of TEM-52 and SHV-2-producing Escherichia coli strains from these animal farms is noteworthy. In contrast, 73% of the strains from pig farms had CTX-M-1, and neither the CMY-type nor CTX-M-9 family enzyme was found. Likewise, it is the first time that CTX-M-1 and SHV-5 encoding strains have been isolated in pigs. On the other hand, in rabbit farms CTX-M-9 family was also the most frequent, being detected in three of a total of four strains. The last one showed a CMY-2, for the first time detected in these animals, too. In conclusion, commensal E. coli strains of food-producing animal farms are a reservoir of ESBL and plasmidic class C beta-lactamases.

A simple phenotypic method for differentiation between acquired and chromosomal AmpC beta-lactamases in Escherichia coli.

BACKGROUND: Screening methods for the detection of plasmid-mediated AmpC beta-lactamases are technically demanding. The purpose of this study was to assess screening methods for the detection of these enzymes in clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. METHODS: Isolates were selected according to a resistance phenotype consistent with production of an AmpC-type beta-lactamase. Detection of acquired ampC genes was done with a multiplex ampC-PCR and sequencing. The phenotypic detection methods evaluated included visual examination of antibiogram plates to identify the presence of scattered colonies located near the edge of the inhibition halo of cefoxitin, cefotaxime, ceftazidime and aztreonam, and a double-disc synergy test using cloxacillin (500 mg) to inhibit AmpC enzymes. RESULTS: Seventy-seven isolates were selected from among 6,209 isolates recovered. Acquired ampC genes (blaCMY-2, blaDHA-1, blaCMY-4 and blaACC-1) were found in 19 (24.7%) of these isolates, including 14 E. coli, two K. pneumoniae and three P. mirabilis isolates. The differential trait for the presence of colonies in the inhibition halo was 100% sensitive and specific. Similar results were obtained for the cloxacillin test, except for the E. coli isolates in which specificity was 10.3%. CONCLUSION: The phenotypic trait described here can be considered useful for suspecting the presence of these enzymes. The cloxacillin test was only useful in isolates lacking a natural AmpC beta-lactamase.

A simple phenotypic method for differentiation between acquired and chromosomal AmpC â -lactamases in Escherichia coli / A simple phenotypic method for differentiation between acquired and chromosomal AmpC â -lactamases in Escherichia coli

Antecedentes. El disponer de métodos fenotípicos para la detección de b-lactamasas AmpC plasmídicas sería de gran utilidad. El objetivo del presente estudio ha sido el de valorar métodos de cribado para la detección de b-lactamasas AmpC plasmídicas en cepas de Escherichia coli, Klebsiella pneumoniae y Proteus mirabilis. Métodos. Se seleccionaron las cepas en función del fenotipo de resistencia compatible con la producción de una b-lactamasa de tipo AmpC. La detección de genes ampC adquiridos se realizó mediante una técnica de multiplex PCR y secuenciación. Los métodos fenotípicos evaluados fueron el examen visual de las placas de antibiograma para detectar colonias en la proximidad del borde de los halos de inhibición de cefoxitina, cefotaxima, ceftazidima y aztreonam, y una prueba de sinergia con doble disco usando cloxacilina (500 mg) como inhibidor de enzimas AmpC. Resultados. Se seleccionaron 77 cepas de las 6.209 aisladas. En 19 (24,7%) cepas que incluyeron 14 E. coli, dos K. pneumoniae y tres P. mirabilis se detectaron genes ampC adquiridos (blaCMY-2, blaDHA-1, blaCMY-4 y blaACC-1). La característica diferencial de la presencia de colonias en el halo de inhibición mostró una sensibilidad y especificidad del 100%. Se obtuvieron resultados similares con el test de cloxacilina, excepto en cepas de E. coli en las que la especificidad fue del 10,3%. Conclusión. La característica fenotípica aquí descrita puede considerarse útil para la sospecha de la presencia de estas enzimas. El test de cloxacilina sólo resulta de utilidad en cepas carentes de una b -lactamasa AmpC cromosómica (AU)

Background. Screening methods for the detection of plasmid-mediated AmpC Beta -lactamases are technically demanding. The purpose of this study was to assess screening methods for the detection of these enzymes in clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. Methods. Isolates were selected according to a resistance phenotype consistent with production of an AmpC-type Beta-lactamase. Detection of acquired ampC genes was done with a multiplex ampC-PCR and sequencing. The phenotypic detection methods evaluated included visual examination of antibiogram plates to identify the presence of scattered colonies located near the edge of the inhibition halo of cefoxitin, cefotaxime, ceftazidime and aztreonam, and a double-disc synergy test using cloxacillin (500 mg) to inhibit AmpC enzymes. Results. Seventy-seven isolates were selected from among 6,209 isolates recovered. Acquired ampC genes (blaCMY-2, blaDHA-1, blaCMY-4 and blaACC-1) were found in 19 (24.7%) of these isolates, including 14 E. coli, two K. pneumoniae and three P. mirabilis isolates. The differential trait for the presence of colonies in the inhibition halo was 100% sensitive and specific. Similar results were obtained for the cloxacillin test, except for the E. coli isolates in which specificity was 10.3%. Conclusion. The phenotypic trait described here can be considered useful for suspecting the presence of these enzymes. The cloxacillin test was only useful in isolates lacking a natural AmpC â-lactamase (AU)

Extended-spectrum beta-lactamase-producing Enterobacteriaceae in different environments (humans, food, animal farms and sewage).

OBJECTIVES: This study aimed to determine the presence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in different environments. METHODS: Clinical samples and stool samples from animal farms, sewage, human faecal carriers attending the emergency room and faecal carriers in the context of food-borne disease outbreaks were subcultured onto MacConkey agar supplemented with cefotaxime for the detection of ESBL-producing Enterobacteriaceae. Identification, susceptibility pattern and ERIC-PCR were used for clone delineation in each sample. Community consumption of antibiotics was also recorded. RESULTS: An ESBL-producing Enterobacteriaceae prevalence of 1.9% was observed in human infections. A cross-sectional survey of human faecal carriers in the community showed a general prevalence of 6.6% with a temporal distribution. High use of antibiotics in winter coincided with a lower prevalence in carriers. ESBL-producing Enterobacteriaceae were detected in the five samples of human sewage, in samples from 8 of 10 pig farms, 2 of 10 rabbit farms, from all 10 poultry farms and in 3 of 738 food samples studied. Faecal carriage of ESBL-producing Enterobacteriaceae was detected in samples from 19 of 61 food-borne outbreaks evaluated. All food-borne outbreaks were due to enteropathogens. The prevalence of carriers in these outbreaks ranged from 4.4% to 66.6%. CONCLUSIONS: This widespread occurrence of ESBL-producing Enterobacteriaceae suggests that the community could act as a reservoir and that food could contribute to the spread of these strains.

Surveillance of extended-spectrum beta-lactamases from clinical samples and faecal carriers in Barcelona, Spain.

OBJECTIVES: The aim of the present study was to characterize and compare the extended-spectrum beta-lactamase (ESBL)-producing organisms isolated from clinical samples and faecal carriers in 2001 and 2002. METHODS: A total of 5251 Enterobacteriaceae isolated from clinical samples and 1321 stool samples were evaluated for the presence of ESBLs. The stool samples were spread onto plates of MacConkey agar containing 2 mg/L cefotaxime for selection of ESBL-producing strains. These strains were defined as those showing synergism between amoxicillin/clavulanic acid and third-generation cephalosporins. The beta-lactamases involved were characterized by isoelectric focusing, PCR assays and DNA sequencing. RESULTS: The prevalence of ESBL-producing strains among clinical Enterobacteriaceae was 1.7%. Of these, 87.6% produced CTX-M, 25.8% produced SHV and 2.2% were TEM-type-producing strains. All clinical ESBL-producing strains were Escherichia coli, with the exception of four Klebsiella pneumoniae and one Citrobacter freundii. The prevalence of faecal carriage of ESBL-producing organisms was 3.3%. Of these, 75% produced CTX-M-type enzymes followed by 22.7% SHV-producing strains. All faecal ESBL-producing strains were E. coli except for one Enterobacter cloacae and one Proteus mirabilis. This latter strain produced the PER-1 enzyme reported for the first time in Spain. CONCLUSIONS: The prevalence of ESBL-producing strains in stool samples was higher than that observed in clinical samples from the same period. The different types of ESBLs found were similar in both contexts. The most prevalent ESBLs were the CTX-M-related enzymes, with nine different types, followed by SHV-12.

Zoogeografía, ecología y protección de la familia Urocoptidae en Cuba (Gastropoda-pulmonata): parte I

Se presentan datos fundamentales con respecto a la distribución zoogeografía y relaciones con el ambiente de los urocóptidos, moluscos de notable antigüedad evolutiva que se encuentran en las antillas, américa central, norte de sudamérica, méxico y suroeste de los estados unidos. En el marco de los crecientes esfuerzos que realiza el gobierno revolucionario para la protección y conservación de la naturaleza, resulta de vital importancia la profundización en el estudio de este grupo, el mejor presentado en la mala-cofauna terrestre de Cuba. Se considera que por su marcada diversificación y endemismo, consecuencia de intensos procesos de especiación y microevolución, estos gastrópodos constituyen un modelo de gran interés para el estudio de la evolución biológica(AU)