Antonia Mantella

Rapid Dissemination and Diversity of CTX-M Extended-Spectrum β-Lactamase Genes in Commensal Escherichia coli Isolates from Healthy Children from Low-Resource Settings in Latin America

ABSTRACT A survey carried out in 2005 among members of a healthy population of children living in Bolivia and Peru revealed that fecal carriage of Escherichia coli strains resistant to expanded-spectrum cephalosporins was remarkably increased compared to that observed in the same settings in 2002 (1.7% in 2005 versus 0.1% in 2002). In this work, we demonstrated that this phenomenon was mainly related to the dissemination of CTX-M-type extended-spectrum β-lactamase (ESBL) determinants among commensal E. coli strains. Of 50 ESBL-producing isolates collected in the 2005 survey, 44 harbored a CTX-M-type and 6 an SHV-type (SHV-2 or SHV-12) ESBL. Compared to 2002 results, an increased diversity of CTX-M-type ESBLs was also observed: members of the CTX-M-1 group (CTX-M-15) emerged in Bolivia (where only CTX-M-2 was observed in 2002), while members of the CTX-M-9 group (CTX-M-14 and CTX-M-24) emerged in Peru (where only CTX-M-15 and CTX-M-2 were observed in 2002). A new CTX-M-2 variant named CTX-M-56 was also detected. Molecular characterization of the CTX-M-producing isolates and gene transfer experiments suggested that different mechanisms could be involved in the spreading of different CTX-M group determinants and revealed that additional resistance determinants for non-β-lactam antibiotics were preferentially carried by plasmids encoding certain CTX-M variants (CTX-M-15 and variants of the CTX-M-2 group). Three CTX-M-15-encoding conjugative plasmids from Peruvian isolates carried the new fluoroquinolone resistance gene aac(6′)-Ib-cr. To our best knowledge, this is the first report of the detection of aac(6′)-Ib-cr in Latin America.

An autochthonous case of Zika due to possible sexual transmission, Florence, Italy, 2014.

We report a case of Zika virus infection imported in Florence, Italy ex-Thailand, leading to a secondary autochthonous case, probably through sexual transmission. The two cases occurred in May 2014 but were retrospectively diagnosed in 2016 on the basis of serological tests (plaque reduction neutralisation) performed on stored serum samples. Our report provides further evidence that sexual transmission of Zika virus is possible.

Zika virus infections imported to Italy: Clinical, immunological and virological findings, and public health implications

We report the first two cases of laboratory confirmed Zika virus (ZIKV) infections imported into Italy from French Polynesia. Both patients presented with low grade fever, malaise, conjunctivitis, myalgia, arthralgia, ankle oedema, and axillary and inguinal lymphadenopathy. One patient showed leukopenia with relative monocytosis and thrombocytopenia. The diagnosis was based on ZIKV seroconversion in both cases and on ZIKV RNA detection in one patient from acute serum sample. Sera from both patients exhibited cross-reactivity with dengue virus antigens. Our immunological analysis demonstrated that recovery from ZIKV infection is associated with restoration of normal numbers of immune cells in the periphery as well as with normal function of antigen-presenting cells. ZIKV is an emerging arbovirus, which has recently spread extensively in tourist destinations on several West Pacific islands. Returning viremic travelers may ignite autochthonous infections in countries like Italy, which are infested by Aedes albopictus, a suitable vector for ZIKV. The role of clinicians is crucial and includes early diagnosis and timely notification of public health authorities in order to quickly implement adequate focal vector control measurements.

Multidrug-resistant commensal Escherichia coli in children, Peru and Bolivia.

Healthy children in urban areas have a high prevalence of fecal carriage of drug-resistant E. coli.

Population Structure and Resistance Genes in Antibiotic-Resistant Bacteria from a Remote Community with Minimal Antibiotic Exposure

ABSTRACT In a previous study, we detected unexpectedly high levels of acquired antibiotic resistance in commensal Escherichia coli isolates from a remote Guaraní Indian (Bolivia) community with very low levels of antibiotic exposure and limited exchanges with the exterior. Here we analyzed the structure of the resistant E. coli population from that community and the resistance mechanisms. The E. coli population (113 isolates from 72 inhabitants) showed a high degree of genetic heterogeneity, as evidenced by phylogenetic grouping (77% group A, 10% group B1, 8% group D, 5% group B2) and genotyping by randomly amplified polymorphic DNA (RAPD) analysis (44 different RAPD types). The acquired resistance genes were always of the same types as those found in antibiotic-exposed settings [blaTEM, blaPSE-1, catI, cmlA6, tet(A), tet(B), dfrA1, dfrA7, dfrA8, dfrA17, sul1, sul2, aphA1, aadA1, aadA2, aadA5, aadB, and sat-1]. Class 1 and class 2 integrons were found in 12% and 4% of the isolates, respectively, and harbored arrays of gene cassettes similar to those already described. The cotransferability of multiple-resistance traits was observed from selected isolates and was found to be associated with resistance conjugative plasmids of the F, P, and N types. Overall, these data suggest that the resistance observed in this remote community is likely the consequence of the dissemination of resistant bacteria and resistance genes from antibiotic-exposed settings (rather than of an independent in situ selection) which involved both the clonal expansion of resistant strains and the horizontal transfer/recombination of mobile genetic elements harboring resistance genes.

High Prevalence of Acquired Antimicrobial Resistance Unrelated to Heavy Antimicrobial Consumption

In a very remote rural Bolivian community where the use of antimicrobials has been minimal and where exchanges with the exterior are very limited, 67% of subjects were found to be carriers of fecal Escherichia coli with acquired resistance to >/=1 antimicrobial agent(s); the highest rates were observed for tetracycline (64%), ampicillin (58%), trimethoprim-sulfamethoxazole (50%), and chloramphenicol (41%). The most relevant implication of these findings is that, in certain settings, the spread and maintenance of antimicrobial resistance can occur, regardless of whether selective pressure generated by the use of antimicrobials is present.

Burden of Unidentifiable Mycobacteria in a Reference Laboratory

ABSTRACT Modern identification techniques at the genomic level have greatly improved the taxonomic knowledge of mycobacteria. In adjunct to nucleic acid sequences, mycobacterial identification has been endorsed by investigation of the lipidic patterns of unique mycolic acids in such organisms. In the present investigation, the routine use of high-performance liquid chromatography (HPLC) of mycolic acids, followed by the sequencing of the 16S rRNA, allowed us to select 72 mycobacterial strains, out of 1,035 screened, that do not belong to any of the officially recognized mycobacterial species. Most strains (i.e., 47) were isolated from humans, 13 were from the environment, 3 were from animals, and 9 were from unknown sources. The majority of human isolates were grown from the respiratory tract and were therefore most likely not clinically significant. Some, however, were isolated from sterile sites (blood, pleural biopsy, central venous catheter, or pus). Many isolates, including several clusters of two or more strains, mostly slow growers and scotochromogenic, presented unique genetic and lipidic features. We hope the data reported here, including the results of major conventional identification tests, the HPLC profiles of strains isolated several times, and the whole sequences of the 16S rRNA hypervariable regions of all 72 mycobacteria, may encourage reporting of new cases. The taxonomy of the genusMycobacterium is, in our opinion, still far from being fully elucidated, and the reporting of unusual strains provides the best background for the recognition of new species. Our report also shows the usefulness of the integration of novel technology to routine diagnosis, especially in cases involving slow-growing microorganisms such as mycobacteria.

Patterns of antimicrobial use and antimicrobial resistance among healthy children in Bolivia

Summary

Detection of CTX-M-Type β-Lactamase Genes in Fecal Escherichia coli Isolates from Healthy Children in Bolivia and Peru

ABSTRACT A survey was carried out from August to November 2002 to evaluate the antimicrobial susceptibilities of fecal Escherichia coli isolates from 3,208 healthy children from four different urban areas of Latin America, two in Bolivia (Camiri and Villa Montes) and two in Peru (Yurimaguas and Moyobamba). Ceftriaxone-resistant E. coli isolates were detected in four children, one from each of the areas sampled. The isolates exhibited a multidrug-resistant phenotype, including resistance to oxyimino-cephalosporins and aztreonam, and the MICs of ceftazidime for the isolates were lower than those of cefotaxime. By PCR and sequencing, the blaCTX-M-2 determinant was detected in three isolates and the blaCTX-M-15 determinant was detected in one isolate (from Peru). The CTX-M-2-producing isolates belonged to three different phylogenetic groups (groups A, B2, and D), while the CTX-M-15-producing isolate belonged to phylogenetic group D. The blaCTX-M-2 determinants were transferable to E. coli by conjugation, while conjugative transfer of the blaCTX-M-15 determinant was not detectable. Plasmids harboring the blaCTX-M-2 determinant exhibited similar restriction profiles, and in all of them the gene was located on a 2.2-kb PstI fragment, suggesting a genetic environment similar to that present in In35 and InS21. The findings of the present study confirm the widespread distribution of CTX-M-type β-lactamases and underscore the role that commensal E. coli isolates could play as a potential reservoir of these clinically relevant resistance determinants. This is the first report of CTX-M-type enzymes in Bolivia and Peru and also the first report of the detection of CTX-M-15 in Latin America.

Antibiotic resistance in a very remote Amazonas community

In a very remote human community of the Peruvian Amazonas with minimal antibiotic exposure, high levels of acquired resistance to the oldest antibiotics (ampicillin, tetracycline, trimethoprim/sulfamethoxazole, streptomycin and chloramphenicol) were detected in commensal Escherichia coli, with remarkable diversity of resistant clones and of resistance genes and plasmids. This pattern was similar overall to that previously observed in a very remote community of Bolivia. It was also similar to that observed in the nearest urban area, except for a lower dominance of resistant isolates and the absolute lack of quinolone resistance in the remote community. Present findings suggest that antibiotic resistance observed in remote communities with minimal antibiotic exposure is a general phenomenon contributed by complex mechanisms and provide new insights into the mechanisms involved in this phenomenon.