CL 64, 855, a potent do anti-Trypanosoma cruzi drug, is also mutagenic in the salmonella/microsome assay

The nitroimidazole-tiadiazole derivative CL 64,855 (2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole, a potent anti-trypanosomal drug, was assayed in a short-term bacterial mutagenicity test with Salmonella typhimurium strains TA 98, TA 100 and TA 102. Results indicate that CL 64,855 is a potent frameshift mutagen detected by strains TA 98 and TA 102. CL 64,855 was able to revert the indicators strains at concentrations as low as 0.1 µg/plate. Metabolic activation experiments with rat liver microsomal fractions did not increase the mutagenic action of Cl 64,855.

Sorotipos de Salmonella isolados de processos entéricos humanos em Recife-Pernambuco, durante o triênio 1978-1980

De 13.196 coproculturas realizadas durante o triênio 1978-1980 em Recife, Pernambuco, foram isoladas 1.720 salmonelas, das quais 1.387 foram caracterizadas sorologicamente. O estudo global possibilitou o reconhecimento de 63 sorotipos concentrados em primeiro plano no grupo sorológico B (73,18%) e identificando-se como tipos mais incidentes: S. typhimurium, S. saint-paul, S. poona, S. derby, S. agona, S. newport, S. oranienburg, S. infantis, S. tshiongwe e S. ndolo, que representaram 1.231 amostras ou 88,75% do total de isolamentos. Algumas considerações de ordem epidemiológica e bacteriológica são discutidas em relação aos quatros sorotipos mais freqüentes.

Rapid detection by transmission electron microscopy of mycoplasma contamination in sera and cell cultures

Transmission electon microscopy has been employed for the rapid detection of mycoplasma in sera and cell cultures. High speed centrifugation of sera or low speed centrifugation of cell debris, followed by negative staining of the resuspended pellet, detected mycoplasma contamination more frequently than a culture method followed by direct fluorescence (DAPI), which was used as a control procedure. The appearance of the mycoplasma cell border and content gives some information about particle viability.

Colicinogeny in Salmonella serovars isolated in Brazil

A study of colicinogeny was made in 748 strains of Salmonella (97 serovars) isolated from different sources; human (291), animal (119), environmental (141), food (102) and animal feed (95). Colicin production was detected in 64 strains (8.6%), particularly isolated from foods (30.4%). Col. E1 (53) and Ia (44) were the most frequently observed, especially in S. agona for environment and food sources. Col V production was identified in 5 strains of S. typhimurium within 8 producer cultures isolated from humans. Its relationship with the sources and serovars of Salmonella are discussed.

A Salmonella agona outbreak in a pediatric hospital in the city of Rio de Janeiro, Brazil

Six Salmonella Agona strains from an outbreak of 15 days duration which occurred in a public hospital in Rio de Janeiro, Brazil, were analyzed. The outbreak involved six infants (mean age, 24 days; mean body weight, 1612 g), all of them with severe clinical signs and symptoms. Two of them had surgical implications, two were preterm and two had respiratory distress at birth. The Salmonella strains were resistant to nine antimicrobial agents (ampicillin, cephalotin, cefriaxone, gentamicin, amykacin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracyclin). Analysis of the plasmid pattern of the wild strains and of the transconjugants confirmed that these were identical strains.

Detection of hilA gene sequences in serovars of Salmonella enterica sufigbspecies enterica

hilA gene promoter, component of the Salmonella Pathogenicity Island 1, has been found in Salmonella serovar Typhimurium, being important for the regulation of type III secretion apparatus genes. We detected hilA gene sequences in Salmonella serovars Typhi, Enteritidis, Choleraesuis, Paratyphi A and B, and Pullorum, by polymerase chain reaction (PCR) and hybridization techniques. The primers to carry out PCR were designed according to hilA sequence. A low stringency hybridization with the probe pVV441 (hilA open-reading-frame plasmid) was carried out. To find hilA gene sequences in other Salmonella sp. suggest that these serovars could have similar sequences of this kind of virulence genes.

The effect of nitric oxide combined with fluoroquinolones against Salmonella enterica serovar Typhimurium in vitro

Two regulons, soxRS and marRAB, are associated with resistance to quinolones or multiple antibiotic in Salmonella enterica serovar Typhimurium. These regulons are activated by nitric oxide and redox-cycling drugs, such as paraquat and cause on activation of the acrAB-encoded efflux pump. In this study, we investigated the effect of nitric oxide (NO) alone and in combination with ofloxacin, ciprofloxacin, and pefloxacin against S. typhimurium clinical isolates and mutant strains in vitro. We did not observe synergistic effect against clinical isolates and SH5014 (parent strain of acr mutant), while we found synergistic effect against PP120 (soxRS mutant) and SH7616 (an acr mutant) S. typhimurium for all quinolones. Our results suggest that the efficiencies of some antibiotics, including ofloxacin, ciprofloxacin, and pefloxacin are decreased via activation of soxRS and marRAB regulons by NO in S. enterica serovar Typhimurium. Further studies are warranted to establish the interaction of NO with the genes of Salmonella and, with multiple antibiotic resistance.

A new serovar and a new serological variant belonging to Salmonella enterica subspecies diarizonae

Description of a new serovar (S. IIIb 16:k:e,n,x,z15) and a new serological variant (S. IIIb 42:z10:e,n,x,z15:z60 ) belonging to the genus Salmonella isolated from stool specimens of Brazilian snakes (Crotalus durissus).

Antimicrobial susceptibility, phage types, and pulsetypes of Salmonella Typhimurium, in São Paulo, Brazil

A total of 283 Salmonella Typhimurium strains isolated from cases of human infections and non human sources, were examined for antimicrobial susceptibilityand the incidence of resistance was 38% and multiple resistance (to three or more antimicrobials) was 15%. All 43 multidrug-resistant strains (MDR) and 13 susceptible ones were characterized by phage typing and pulsed- field gel electrophoresis (PFGE). The strains encompassed 14 definitive phage types (DT), three were untypable (UT), and 18 atypicals or reaction does not conform (RDNC), which belonged to 21 PFGE patterns, A1-A21. The predominant phage types were DT49, DT193, and RDNC and two strains belonging to DT 104 and 104b were also identified. The most commum PFGE patterns were A1 and A8. Analysis by PFGE and phage typing demonstrated that the most of the MDR were multiclonal and association among multiresistance, phage typing, and PFGE patterns was not so significant.

Anti-flagellin antibody responses elicited in mice orally immunized with attenuated Salmonella enterica serovar Typhimurium vaccine strains

In the present study we investigated the flagellin-specific serum (IgG) and fecal (IgA) antibody responses elicited in BALB/c mice immunized with isogenic mutant derivatives of the attenuated Salmonella enterica serovar Typhimurium (S. Typhimurium) SL3261 strain expressing phase 1 (FliCi), phase 2 (FljB), or no endogenous flagellin. The data reported here indicate that mice orally immunized with recombinant S. Typhimurium strains do not mount significant systemic or secreted antibody responses to FliCi, FljB or heterologous B-cell epitopes genetically fused to FliCi. These findings are particularly relevant for those interested in the use of flagellins as molecular carriers of heterologous antigens vectored by attenuated S. Typhimurium strains.

Tracing lineage by phenotypic and genotypic markers in Salmonella enterica subsp. enterica serovar 1,4,[5],12:i:- and Salmonella Typhimurium isolated in state of São Paulo, Brazil

Fifty-three Salmonella 1,4,[5],12:i:- and 45 Salmonella Typhimurium strains were characterised using phage typing, plasmid profiles and pulsed-field gel electrophoresis (PFGE) for comparison. The majority of the strains were subdivided into definitive type (DT) 41 (22.6%) and DT 193 (18%) and the 60-MDa plasmid was detected in 94.3% and 84.4% of strains, respectively. Genetic diversity was observed among all strains and 90% presented a > 70% similarity through PFGE analysis. These results suggest a close relationship between Salmonella 1,4,[5],12:i:- and Salmonella Typhimurium at the serotype level.

TLR5-dependent immunogenicity of a recombinant fusion protein containing an immunodominant epitope of malarial circumsporozoite protein and the FliC flagellin of Salmonella Typhimurium

Recently, we described the improved immunogenicity of new malaria vaccine candidates based on the expression of fusion proteins containing immunodominant epitopes of merozoites and Salmonella enterica serovar Typhimurium flagellin (FliC) protein as an innate immune agonist. Here, we tested whether a similar strategy, based on an immunodominant B-cell epitope from malaria sporozoites, could also generate immunogenic fusion polypeptides. A recombinant His6-tagged FliC protein containing the C-terminal repeat regions of the VK210 variant of Plasmodium vivax circumsporozoite (CS) protein was constructed. This recombinant protein was successfully expressed in Escherichia coli as soluble protein and was purified by affinity to Ni-agarose beads followed by ion exchange chromatography. A monoclonal antibody specific for the CS protein of P. vivax sporozoites (VK210) was able to recognise the purified protein. C57BL/6 mice subcutaneously immunised with the recombinant fusion protein in the absence of any conventional adjuvant developed protein-specific systemic antibody responses. However, in mice genetically deficient in expression of TLR5, this immune response was extremely low. These results extend our previous observations concerning the immunogenicity of these recombinant fusion proteins and provide evidence that the main mechanism responsible for this immune activation involves interactions with TLR5, which has not previously been demonstrated for any recombinant FliC fusion protein.