Peptides for Coating TiO2 Implants: An In Silico Approach.

Titanium is usually used in the manufacturing of metal implants due to its biocompatibility and high resistance to corrosion. A structural and functional connection between the living bone and the surface of the implant, a process called osseointegration, is mandatory for avoiding prolonged healing, infections, and tissue loss. Therefore, osseointegration is crucial for the success of the implantation procedure. Osseointegration is a process mediated by bone-matrix progenitor cells' proteins, named integrins. In this study, we used an in silico approach to assemble and test peptides that can be strategically used in sensitizing TiO2 implants in order to improve osseointegration. To do so, we downloaded PDB structures of integrins α5ß1, αvß3, and αIIbß3; their biological ligands; and low-cost proteins from the Protein Data Bank, and then we performed a primary (integrin-protein) docking analysis. Furthermore, we modeled complex peptides with the potential to bind to the TiO2 surface on the implant, as well as integrins in the bone-matrix progenitor cells. Then we performed a secondary (integrin-peptide) docking analysis. The ten most promising integrin-peptide docking results were further verified by molecular dynamics (MD) simulations. We recognized 82 peptides with great potential to bind the integrins, and therefore to be used in coating TiO2 implants. Among them, peptides 1 (GHTHYHAVRTQTTGR), 3 (RKLPDATGR), and 8 (GHTHYHAVRTQTLKA) showed the highest binding stability during the MD simulations. This bioinformatics approach saves time and more effectively directs in vitro studies.

Genetic and Biochemical Diversity of Clinical Acinetobacter baumannii and Pseudomonas aeruginosa Isolates in a Public Hospital in Brazil.

Life-threatening bacterial infections are a major concern in health care services worldwide. This retrospective study aimed to demonstrate genetic and biochemical diversity in isolates of Acinetobacter baumannii and Pseudomonas aeruginosa from a public hospital in Brazil. A total of 63 isolates collected from different sites of infection and hospital sectors were characterized, and their susceptibility profile to antibiotics was assessed for 18 drugs belonging to 8 antimicrobial categories using the automated BACTEC system. Genetic diversity was assessed using the multiple locus variable number tandem repeat analysis. Among the isolates of A. baumannii, 83% were classified as extensively drug resistant (XDR), and 17 genotypic profiles were identified. About 67% of P. aeruginosa isolates were susceptible to antimicrobials and were distributed into 37 genotypic profiles, revealing genetic heterogeneity. This study has demonstrated the multicolonization of investigated pathogens and the high frequency (95.8%) of multidrug-resistant and XDR, as well as high genetic diversity, among the isolates supporting the continuous need to monitor these species in the hospital environment.

High-resolution genome-wide analysis is essential for the identification of ambiguous Aeromonas strains.

Aeromonads are mainly opportunistic pathogens; however, many species are emerging as important human pathogens. Therefore, monitoring these bacteria and their accurate characterization of its species is highly important. Aeromonas Aer593 strain was recovered from a diarrhoea outbreak and did not group with any previously described Aeromonas species by housekeeping gene sequencing. To clarify the taxonomic position of Aer593, its genome was sequenced and analysed by multilocus phylogenetic analysis (MLPA), in silico DNA-DNA hybridization (isDDH), average nucleotide identity (ANI) and core genome-based phylogenetic analyzes. The MLPA with the housekeeping genes gyrB, rpoD, recA, dnaJ, gyrA and dnaX ranked the Aer593 isolate into an independent branch suggesting that it could represent a new species. However, the identity percentages of Aer593 to A. caviae strains using robust genomic analysis by isDDH and ANI were at least 81.3% and 97.8%, respectively, defining Aer593 as A. caviae. Multilocus sequence typing (MLST) presented an exact match against only a single allele (groL96) and the novel ST648 was assigned for this strain. The core genome-based phylogenetic analyses with a total of 863 orthologous genes also grouped the Aer593 isolate with A. caviae reference strains. These findings warn about the possibility of misidentification of some Aeromonas strains by MLPA and show that high-resolution genome-wide analysis is essential for the correct identification of ambiguous Aeromonas strains.

Genetic diversity and virulence potential of clinical and environmental Aeromonas spp. isolates from a diarrhea outbreak.

BACKGROUND: Aeromonas spp. are gram-negative bacteria that can cause a variety of infections in both humans and animals and play a controversial role in diarrhea outbreaks. Our aim was to identify clinical and environmental Aeromonas isolates associated with a cholera outbreak in a northeast county of Brazil at the species level. We also aimed to determine the genetic structure of the bacterial population and the virulence potential of the Aeromonas isolates. METHODS AND RESULTS: Analysis based on concatenated sequences of the 16S rRNA and gyrB genes suggested the classification of the 119 isolates studied into the following species: A. caviae (66.9%), A. veronii (15.3%), A. aquariorum (9.3%), A. trota (3.4%), A. hydrophila (3.4%) and A. jandaei (1.7%). One isolate did not fit any Aeromonas species assessed, which might indicate a new species. The haplotype network based on 16S rRNA gene sequences identified 59 groups among the 119 isolates and 26 reference strains, and it clustered almost all A. caviae isolates into the same group. The analysis of the frequency patterns of seven virulence-associated genes (alt, ast, hlyA, aerA, exu, lip, flaA/B) revealed 29 virulence patterns composed of one to seven genes. All the isolates harbored at least one gene, and three of them harbored all seven virulence genes. CONCLUSION: The results emphasize the need to improve local water supply and maintain close monitoring of possible bacterial contamination in the drinking water.

High Frequency of OXA-253-Producing Acinetobacter baumannii in Different Hospitals in Recife, Brazil.

Here, we report the isolation of 31 Acinetobacter baumannii strains producing OXA-253 in a single large Brazilian city. These strains belonged to five different sequence types (STs), including 4 STs not previously associated with blaOXA-253 In all strains, the blaOXA-253 gene was located in a plasmid within a genetic environment similar to what was found previously in Brazil and Italy. The reported data emphasize the successful transmission of the blaOXA-253 gene through a large area and the tendency for this resistance determinant to remain in the A. baumannii population.

Development of duplex-PCR for identification of Aeromonas species

Introduction The number of reports of intestinal infections caused by Aeromonas spp. has increased significantly in recent years. In most clinical laboratories, identification of these bacteria is carried out by general phenotypic tests that sometimes do not accurately differentiate Aeromonas and Vibrio. Methods A duplex-polymerase chain reaction (PCR) was developed directed to 2 targets identifying Aeromonas spp. pathogenic to humans. Results The duplex-PCR results were reproducible and specific for Aeromonas spp. pathogenic to humans. Conclusions This method will allow differentiation between Vibrio and Aeromonas spp. in patients with in cholera-like symptoms and can also be used in water quality monitoring. .

Development of duplex-PCR for identification of Aeromonas species.

INTRODUCTION: The number of reports of intestinal infections caused by Aeromonas spp. has increased significantly in recent years. In most clinical laboratories, identification of these bacteria is carried out by general phenotypic tests that sometimes do not accurately differentiate Aeromonas and Vibrio. METHODS: A duplex-polymerase chain reaction (PCR) was developed directed to 2 targets identifying Aeromonas spp. pathogenic to humans. RESULTS: The duplex-PCR results were reproducible and specific for Aeromonas spp. pathogenic to humans. CONCLUSIONS: This method will allow differentiation between Vibrio and Aeromonas spp. in patients with in cholera-like symptoms and can also be used in water quality monitoring.

The aquatic environment as a reservoir of Vibrio cholerae O1 in hydrographic basins of the state of Pernambuco, Brazil.

After the worldwide cholera epidemic in 1993, permanent environmental monitoring of hydrographic basins was established in Pernambuco, Brazil, where cholera is endemic. After a quiescent period, 4 rfbN (serogroup O1) positive water samples that were culture negative were detected by multiplex single-tube nested PCR (MSTNPCR); 2 of these were also ctxA (cholera toxin) positive. From May to June 2012, 30 V. cholerae O1 isolates were obtained by culturing samples. These isolates were analyzed for the presence of virulence genes by PCR, intergenic spacer region 16S-23S PCR (ISR-PCR), and pulsed field gel electrophoresis (PFGE). The isolates were positive for the rfbN gene and negative for the assessed pathogenic genes and were classified into 2 groups by ISR and the same profile by PFGE. Close genetic similarity was observed between them (2012) and environmental strains from 2004 to 2005, indicating the permanence of endemic V. cholerae O1 in the region.

Molecular characterization of Aeromonas spp. and Vibrio cholerae O1 isolated during a diarrhea outbreak / Caracterização molecular de Aeromonas spp. e Vibrio cholerae O1 isolados durante um surto de diarréia

This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.

O objetivo deste trabalho foi estabelecer o potencial patogênico e a relação clonal de isolados de Aeromonas sp. e Vibrio cholerae obtidos durante um surto de diarréia. Isolados clínicos e ambientais foram investigados quanto à presença de genes de virulência e sua relação clonal foi obtida através de amplificação da Região Espaçadora Intergênica (REI) 16S-23S. Quatro genes de Aeromonas (lip, exu, gcat, flaA/B) foram encontrados em alta frequência embora o gene lip tenha se mostrado ausente em algumas espécies. Um quinto gene, aerA, foi raramente encontrado em A. caviae, a espécie mais abundante. O perfil da REI revelou alta heterogeneidade entre os isolados de Aeromonas e nenhuma correlação com espécie. Em contraste, todas as amostras de V. cholerae amplificaram os genes investigados (ctxA, tcpA, zot e ace) e revelaram perfil clonal através de REI e RAPD. Embora Aeromonas tenha sido o principal patógeno isolado, o perfil da REI não é compatível como única causa para os eventos de diarréia, enquanto a relação clonal de V. cholerae aponta esse microrganismo como o provável agente do surto. Estes resultados reforçam a necessidade de definir melhor o papel de Aeromonas em diarréias e de que forma essas bactérias se beneficiam quando em co-infecção com V. cholerae.

Molecular characterization of Aeromonas spp. and Vibrio cholerae O1 isolated during a diarrhea outbreak.

This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.