The proportion of ESBL-producing enterobacteria in Uruguay's paediatric hospital during the study period was 2.3 per 1000 hospitalized patients. The number of different microorganisms detected, as well as the various EBSLs, suggests the occurrence of sporadic episodes instead of nosocomial outbreaks. Nevertheless, the presence of new resistance genes reinforces the necessity for permanent surveillance programmes.

The aim of this work was to study the prevalence of Listeria monocytogenes in foods obtained in retail shops and food industries located in Montevideo-Uruguay, and to identify the serogroups of the obtained isolates. Three-thousand one-hundred and seventy-five food samples (frozen, deli meats, ready-to-eat and cheese) were analyzed. The obtained isolates were serogrouped by multiplex PCR and serotyped by conventional procedure. Genetic comparisons were performed using pulsed-field gel electrophoresis on a sub-set of isolates belonging to the same serotype successively recovered from the same establishment. L. monocytogenes was isolated from 11.2% of samples. The highest prevalence was observed in frozen foods (38%), followed by cheese (10%). 1/2b and 4b were the most frequently identified serotypes. In six of 236 analyzed establishments we successively recovered L. monocytogenes isolates belonging to the same serotype. Most of them corresponded to serotype 1/2b. Pulsed-field gel electrophoresis profiles suggest that at least 33% of L. monocytogenes 1/2b isolates are genetically related and that may remain viable for prolonged periods. The observed prevalence of L. monocytogenes was lower than reported in neighboring countries. Our findings highlight the role that frozen foods may play in the spread of this pathogen, and the relevance of serotypes 1/2b and 4b.

One hundred and twenty-six epidemiologically sequential, unrelated, carbapenem-resistant Acinetobacter baumannii isolates from nine hospitals in six countries of South America were collected between July 2013 and June 2014. Genes coding for Ambler class D and B carbapenemases were sought by PCR. All isolates were typed using the 3-locus sequence typing and blaOXA-51-like sequence-based typing techniques. The blaOXA-23 gene was recovered in all the participating hospitals and in all the isolates of seven of nine medical centres. The blaOXA-72 gene was only recovered in the two medical centres from Guayaquil city, Ecuador. Trilocus sequence typing revealed the presence of sequence groups SG2, SG4 and SG5. blaOXA-51-like sequence-based typing revealed the presence of blaOXA-132, blaOXA-65, blaOXA-69 and blaOXA-64. Our results showed that the population of carbapenem-resistant A. baumannii in South America was principally associated with ST79, ST25 and ST15 (92 %) and harboured the blaOXA-23 gene mainly. CC2 was not detected.

We studied 13 extended-spectrum ␤-lactamase (ESBL)-producing enteropathogenic Escherichia coli isolates from children suffering acute diarrhea in Uruguay. ESBL characterization in crude extracts showed a single band at pI 5.4. PCR amplification and sequencing data allowed identification of bla PER-2 and bla TEM-116 . Retrospective analysis suggests that these strains were disseminated in the community, even if unnoticed, prior to their access to the hospital environment more than a decade ago.

We analyzed 90 nonduplicates community-associated methicillin-resistant S. aureus (CA-MRSA) strains isolated from skin and soft-tissue infections. All strains were mecA positive. Twenty-four of the 90 strains showed inducible macrolide-lincosamide-streptogramin B resistance. All strains produced α-toxin; 96% and 100% of them displayed positive results for lukS-F and cna genes, respectively. Eigthy-five strains expressed capsular polysaccharide serotype 8. Six different pulsotypes were discriminated by pulsed-field gel electrophoresis (PFGE) and three predominant groups of CA-MRSA strains (1, 2, and 4) were identified, in agreement with phenotypic and genotypic characteristics. Strains of group 1 (pulsotype A, CP8+, and Panton-Valentine leukocidin (PVL)+) were the most frequently recovered and exhibited a PFGE band pattern identical to other CA-MRSA strains previously isolated in Uruguay and Brazil. Three years after the first local CA-MRSA report, these strains are still producing skin and soft-tissue infections demonstrating the stability over time of this community-associated emerging pathogen.

A small (8.2-kb) ColE1 plasmid encoding TEM-144 (a new ␤-lactamase with a ceftazidimase profile) was sequenced by a gene-walking strategy. The bla TEM allele was carried on a Tn2 element, disrupting a Rom protein gene. TEM-144 differs from TEM-1 by two mutations (R164C and E240K) and from the ceftazidimehydrolyzing TEM-91 by one mutation (T182M).The TEM-derived extended-spectrum ␤-lactamases (ESBLs) include more than 100 variants (11) originated by one to four amino acidic modifications relative to TEM-1 or TEM-2. Modifications of a few residues have been described to be responsible for TEM-derived ESBL activity, namely, Glu-104, . Interestingly, bla TEM genes are frequently embedded in transposable elements such as Tn2 inserted in wide-host-range plasmids (12).Two Salmonella enterica serovar Derby isolates with decreased susceptibility to ceftazidime were detected in a previous study of samples of poultry origin (6). An 8.2 kb-plasmid (pSD1 and pST12) was obtained from isolates SD1 and ST12. Both plasmids showed identical restriction patterns when digested with PstI, displaying three fragments of about 5, 3, and 0.7 kb (data not shown), and could be transferred by transformation (24) coli Genetic Stock Center). MICs were determined as specified by the CLSI (formerly NCCLS) (18). Both transformants CAG12177/pSD1 and CAG12177/pST12 had identical antibiotic susceptibility profiles, which were also similar to those of isolates SD1 and ST12 (Table 1). The MICs of ceftriaxone and ceftazidime, with and without clavulanic acid, suggested that they produced enzymes hydrolyzing ceftazidime more efficiently than ceftriaxone (Table 1). Transformants remained fully susceptible to the carbapenems and to other families of antibiotics such as aminoglycosides, tetracyclines, quinolones, and sulfonamides.Crude extracts of both original and transformant strains displayed, after isoelectrofocusing (21), a single ␤-lactam-hydrolyzing band at an apparent pI of 5.6 when revealed with 0.5 mM nitrocefin (data not shown).PCRs (25) with specific bla TEM primers were positive when plasmid DNA (both from the original poultry isolates as well as from the transformants) was used as a template but yielded negative results with primers specific for bla SHV , bla CTX-M , bla PER-2 , and bla OXA genes (for primer descriptions, see Table 2). Sequence analysis of PCR products revealed the presence of a bla TEM allele encoding a new TEM-derived enzyme, showing two amino acid differences compared to TEM-1 (R164C and E240K). These modifications occurred by two nucleotide substitutions (in boldface type): CGT3TGT at position 692 and GAG3AAG at position 917, respectively, as described previously by Ambler et al. (1). Only one difference could be detected compared with TEM-91 (13), namely, T182M (ATG3ACG). The amino acidic sequence of mature TEM-144 had a predicted pI of 5.6, consistent with the value previously observed by isoelectric focusing.TEM-144 has two mutations known to be involved in the extension of substrate specificity of TEM-type enzymes ...

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Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes are worldwide recognized zoonotic pathogens. Recent reports have emerged about the circulation of antimicrobial-resistant STEC and L. monocytogenes isolates. To assess the frequency of antimicrobial resistance and related genes in these pathogens, we studied 45 STEC and 50 L. monocytogenes isolates locally recovered from different sources. Antimicrobial susceptibility testing was performed by disk-diffusion method, and the genomic sequences of three selected STEC and from all 50 L. monocytogenes isolates were analyzed for antibiotic resistance genes. Four STEC and three L. monocytogenes isolates were phenotypically resistant to at least one of the antibiotics tested. Resistance genes aph(3 ′′)-Ib, aph(3 ′)-Ia, aph(6)-Id, bla T EM−1B , sul2, mef(A), and tet(A) were found in a human STEC ampicillin-resistant isolate. All L. monocytogenes isolates harbored fosX, lin, mdrL, lde fepA, and norB. Overall resistance in L. monocytogenes and STEC was low or middle. However, the high load of resistance genes found, even in susceptible isolates, suggests that these pathogens could contribute to the burden of antimicrobial resistance.