Genomic characterization of Salmonella enterica serovar Choleraesuis from Brazil reveals a swine gallbladder isolate harboring colistin resistance gene mcr-1.1.

Salmonella enterica serovar Choleraesuis (S. Choleraesuis) is a swine-adapted serovar associated to invasive infections in humans. In Brazil, data of strains of this serovar are scarce. In the present study, six S. Choleraesuis strains of animal (n = 5) and human (n = 1) origin from Brazil were screened for phenotypic antimicrobial resistance using disk-diffusion assay and using whole-genome sequencing data to search for antimicrobial resistance genes, plasmids, prophages, and Salmonella pathogenicity islands (SPIs). Its genetic relatedness was evaluated by MLST and SNP analysis. A single isolate from swine gallbladder harbored the colistin resistance gene mcr-1.1 into a IncX4 plasmid. In the six strains analyzed, resistance was found to tetracycline, nalidixic acid, ciprofloxacin, ampicillin, piperacillin, streptomycin, cefazoline, gentamycin, sulfamethoxazole-trimethoprim, and choloramphenicol, along with resistance genes aac(6')-Iaa, aac(3)-IV, aph(3'')-Ib, aph(6)-Id, aph(4)-Ia, aadA1, aph(3')-IIa, blaTEM-1A, floR, sul1, sul2, tet(B), drfA1, erm(B), mph(B), lnu(G), qacE, and gyrA point mutation Serine83 → Tyrosine and parC Threonine57 → Serine. Furthermore, IncF and IncH plasmids, ten SPIs, and seven prophage types were detected. All strains were assigned to ST145 and five belonged to a common SNP cluster of S. Choleraesuis strains from Brazil. The presence of S. Choleraesuis isolated from animals harboring relevant antimicrobial resistance profiles and virulence determinants reinforced the urge for enhanced surveillance to avoid its transmission to humans through food items.

Structural and Biochemical Characterization of the Novel CTX-M-151 Extended-Spectrum ß-Lactamase and Its Inhibition by Avibactam.

The diazabicyclooctane (DBO) inhibitor avibactam (AVI) reversibly inactivates most serine ß-lactamases, including the CTX-M ß-lactamases. Currently, more than 230 unique CTX-M members distributed in five clusters with less than 5% amino acid sequence divergence within each group have been described. Recently, a variant named CTX-M-151 was isolated from a Salmonella enterica subsp. enterica serovar Choleraesuis strain in Japan. This variant possesses a low degree of amino acid identity with the other CTX-Ms (63.2% to 69.7% with respect to the mature proteins), and thus it may represent a new subgroup within the family. CTX-M-151 hydrolyzes ceftriaxone better than ceftazidime (kcat/Km values 6,000-fold higher), as observed with CTX-Ms. CTX-M-151 is well inhibited by mechanism-based inhibitors like clavulanic acid (inactivation rate [kinact]/inhibition constant [Ki ] = 0.15 µM-1 · s-1). For AVI, the apparent inhibition constant (Kiapp), 0.4 µM, was comparable to that of KPC-2; the acylation rate (k2/K) (37,000 M-1 · s-1) was lower than that for CTX-M-15, while the deacylation rate (koff) (0.0015 s-1) was 2- to 14-fold higher than those of other class A ß-lactamases. The structure of the CTX-M-151/AVI complex (1.32 Å) reveals that AVI adopts a chair conformation with hydrogen bonds between the AVI carbamate and Ser70 and Ser237 at the oxyanion hole. Upon acylation, the side chain of Lys73 points toward Ser130, which is associated with the protonation of Glu166, supporting the role of Lys73 in the proton relay pathway and Glu166 as the general base in deacylation. To our knowledge, this is the first chromosomally encoded CTX-M in Salmonella Choleraesuis that shows similar hydrolytic preference toward cefotaxime (CTX) and ceftriaxone (CRO) to that toward ceftazidime (CAZ).

Chlorine dioxide: an evaluation based on a microbial decay approach during mango packing process.

Mango is highly consumed worldwide; nonetheless, its consumption has been related to foodborne outbreaks. This study was performed to evaluate bacterial transference during mango postharvest management and the feasibility of adopting chlorine dioxide as first choice disinfectant in mango packinghouse. Chlorine dioxide (3 and 5 ppm) and sodium hypochlorite (100 and 200 ppm) were evaluated at different turbidity and times against Salmonella Choleraesuis and Listeria monocytogenes. Bacterial transference was higher from water to fruit than vice-versa (49.17%). Chlorine dioxide (5 ppm) achieved the highest Salmonella reductions at low turbidity reaching 2.13 Log10 at 10 min; meanwhile, Listeria was totally reduced in all conditions. Bacterial decay kinetic showed that chlorine dioxide 5 ppm was 34-fold faster than sodium hypochlorite at 200 ppm in reducing 1 Log10 of Salmonella. Chlorine dioxide reached faster bacterial inactivation decay over sodium hypochlorite; its usage is safe and meets the regulatory standards set for mango processing.

Use of allyl isothiocyanate and carbon nanotubes in an antimicrobial film to package shredded, cooked chicken meat.

We developed antimicrobial packaging incorporated with allyl isothiocyanate (AIT) and carbon nanotube (CNT), and this packaging was used for shredded cooked chicken meat inoculated with Salmonella Choleraesuis. The following parameters were analysed during the 40 days of storage: microbial counts, colour characteristics and changes in the oxidation of the meat as well as changes in the mechanical properties of the film, the structure of the antimicrobial film and the diffusion of the antimicrobial agent into the food. The incorporation of AIT into the films increased the elongation at the break (E) value of the films and decreased the tensile strength (TS) value of the films. The CNT was important to retain the AIT which is a volatile substance in the film. The diffusion of the AIT from the film into the chicken reduced the microbial contamination, controlled oxidation and reduced the colour changes. Thus, these packages were effective for the 40 days of storage.

Septicemia por salmonella no tiphy / Salmonella non tiphy septicemia

Se trata de un paciente con tos de 5 meses de evolución, fiebre de 3 meses, que ha visto otros servicios de salud para solucionar su problema. Con investigaciones negativas para tuberculosis, un cultivo de esputo con klebsiella Pneumoniae por lo que recibió ciprofloxacina durante 5 días. Viene al hospital Vozandes Quito, aún con fiebre, malestar genera y odinofagia. En el examen físico un eritema leve en orofaringe y un ganglio cervical, el resto normal. Es hospitalizado como fiebre de origen desconocido y se inicia investigaciones básicas que inicialmente destacan alteración en reactantes de fase aguda y hepatopatía. Con exámenes más invasivos se dermina por un mielocultivo la presencia de salmonella cholerasuis. Luego de 4 días de 2 gramos diarios de ceftriaxona intravenosa cede la fiebre. A los 7 días de antibióticoterapia sistémica, sale con el alta y toma ciprofloxacina 750 mg dos veces al día por 10 días más. Presentamos dos revisiones bibliográficas sobre fiebre de origen a determinar y salmonellosis por choleraesuis. En el Ecuador se han reportado pocos casos de infección por salmonella cholerasuis, en un estudio realizado en 1989 y 1993 entre todas las especies de salmonelas el 36% eran de serotipo Cholerasuis, Se ha aislado de tejidos de pollo, a diferencia de Asia donde es frecuente que habite en cerdos. Se transmite a través agua y alimentos contaminados. Se caracteriza por dos tipos de presentación clínica: Síndrome e bacteriemia sostenida con fiebre e infecciones focales extraintestinales. Todavía no hemos encontrado resistencia antibiótica, como se ha reportado en otros países.

This is a patient with a cough of 5 months of evolution, fever of 3 months, who has seen other health services to solve his problem. With negative investigations for tuberculosis, a sputum culture with klebsiella Pneumoniae so he received ciprofloxacin for 5 days. He comes to the Vozandes Quito hospital, even with fever, general discomfort and odynophagia. On physical examination, a slight erythema in the oropharynx and a cervical ganglion, the rest normal. He is hospitalized as a fever of unknown origin and basic investigations are started that initially highlight alteration in acute phase reactants and liver disease. With more invasive examinations, the presence of salmonella cholerasuis is revealed by a myeloculture. After 4 days of 2 grams daily of intravenous ceftriaxone fever subsides. After 7 days of systemic antibiotic therapy, she is discharged and takes ciprofloxacin 750 mg twice a day for 10 more days. We present two bibliographic reviews on fever of origin to be determined and choleraesuis salmonellosis. In Ecuador, few cases of salmonella cholerasuis infection have been reported. In a study carried out in 1989 and 1993, 36% of all salmonella species were of the Cholerasuis serotype. They have been isolated from chicken tissues, unlike Asia, where it is frequently inhabits pigs. It is transmitted through contaminated food and water. It is characterized by two types of clinical presentation: syndrome and sustained bacteremia with fever and focal extra-intestinal infections. We have not yet found antibiotic resistance, as has been reported in other countries.