Molecular epidemiology of hepatitis B virus among the indigenous population of the Curuçá and Itaquaí Rivers, Javari Valley, State of Amazonas, Brazil

INTRODUCTION: Hepatitis B virus (HBV) infection is one of the most serious public health problems in the world. In Brazil, HBV endemicity is heterogeneous, with the highest disease prevalence in the North region. METHODS: A total of 180 samples were analyzed and subjected to polymerase chain reaction (PCR) and semi-nested PCR of the HBV S-gene, with the aim of determining the prevalence of HBV-DNA (deoxyribonucleic acid) in indigenous groups inhabiting the areas near the Curuçá and Itaquaí Rivers in the Javari Valley, State of Amazonas, Brazil. RESULTS: The prevalence of the HBV-DNA S-gene was 51.1% (92/180). The analysis found 18 of 49 (36.7%) samples from the Marubo tribe, 68 of 125 (54.4%) from the Kanamary, and 6 of 6 (100%) from other ethnic groups to be PCR positive. There was no statistically significant difference in gender at 5% (p=0.889). Indigenous people with positive PCR for HBV-DNA had a lower median age (p<0.001) of 23 years. There was no statistical difference found in relation to sources of contamination or clinical aspects with the PCR results, except for fever (p<0.001). The high prevalence of HBV-DNA of 75% (15/20) in pregnant women (p=0.009) demonstrates an association with vertical transmission. CONCLUSIONS: The results confirm the high prevalence of HBV-DNA in the Javari Valley, making it important to devise strategies for control and more effective prevention in combating the spread of HBV.

New focus of active transmission of Chagas disease in indigenous populations in the Peruvian Amazon basin

Introduction Several cases of acute Chagas disease (ACD) have been reported in the Peruvian Amazon basin. Methods The objective was to describe and investigate 6 ACD cases in children from indigenous Amazon communities in the province of Datem del Marañón in Loreto department (2006-2010). Results The mean age was 3.6 years. All patients had fever, 4/6 hepatomegaly, 2/6 splenomegaly, and 5/6 had trypomastigotes of Trypanosoma cruzi on thick smears. The fatality rate was 33.3%. Rhodnius pictipes and Rhodnius robustus adults were found inside the homes and in the peri-domiciles. Conclusions All cases reported were isolated cases. We report a new focus of ACD in indigenous populations.

Ants in a hospital environment and their potential as mechanical bacterial vectors

Introduction We studied the richness and abundance of ant species, their bacteria and the bacteria isolated from patient clinical samples. Methods Ants were collected with baited traps at 64 sites in a public hospital in São Luis, State of Maranhão, Brazil. Results In total, 1,659 ants from 14 species were captured. The most frequent species were Crematogaster victima, Solenopsis saevissima, Tapinoma melanocephalum, Camponotus vittatus and Paratrechina fulva. Forty-one species of bacteria were isolated from the ants and 18 from patients. Conclusions Ants are potential vehicles for pathogenic and opportunistic bacteria, and they can represent a risk factor in nosocomial infections.

Performance of the Vitek 2 system software version 5.03 in the bacterial identification and antimicrobial susceptibility test: evaluation study of clinical and reference strains of Gram-positive cocci

Introduction. The genera Enterococcus, Staphylococcus and Streptococcus are recognized as important Gram-positive human pathogens. The aim of this study was to evaluate the performance of Vitek 2 in identifying Gram-positive cocci and their antimicrobial susceptibilities. Methods. One hundred four isolates were analyzed to determine the accuracy of the automated system for identifying the bacteria and their susceptibility to oxacillin and vancomycin. Results. The system correctly identified 77.9% and 97.1% of the isolates at the species and genus levels, respectively. Additionally, 81.8% of the Vitek 2 results agreed with the known antimicrobial susceptibility profiles. Conclusion. Vitek 2 correctly identified the commonly isolated strains; however, the limitations of the method may lead to ambiguous findings.

Colistin and anti-Gram-positive bacterial agents against Acinetobacter baumannii

Introduction Acinetobacter baumannii has attained an alarming level of resistance to antibacterial drugs. Clinicians are now considering the use of older agents or unorthodox combinations of licensed drugs against multidrug-resistant strains to bridge the current treatment gap. We investigated the in vitro activities of combination treatments that included colistin with vancomycin, norvancomycin or linezolid against multidrug-resistant Acinetobacter baumannii. Methods The fractional inhibitory concentration index and time-kill assays were used to explore the combined effects of colistin with vancomycin, norvancomycin or linezolid against 40 clinical isolates of multidrug-resistant Acinetobacter baumannii. Transmission electron microscopy was performed to evaluate the interactions in response to the combination of colistin and vancomycin. Results The minimum inhibitory concentrations (MICs) of vancomycin and norvancomycin for half of the isolates decreased below the susceptibility break point, and the MIC of linezolid for one isolate was decreased to the blood and epithelial lining fluid concentration using the current dosing regimen. When vancomycin or norvancomycin was combined with subinhibitory doses of colistin, the multidrug-resistant Acinetobacter baumannii test samples were eradicated. Transmission electron microscopy revealed that subinhibitory doses of colistin were able to disrupt the outer membrane, facilitating a disruption of the cell wall and leading to cell lysis. Conclusions Subinhibitory doses of colistin significantly enhanced the antibacterial activity of vancomycin, norvancomycin, and linezolid against multidrug-resistant Acinetobacter baumannii.

Aerobic bacterial profile and antibiotic resistance in patients with diabetic foot infections

ABSTRACTINTRODUCTION: This study aimed to determine the frequencies of bacterial isolates cultured from diabetic foot infections and assess their resistance and susceptibility to commonly used antibiotics.METHODS: This prospective study included 41 patients with diabetic foot lesions. Bacteria were isolated from foot lesions, and their antibiotic susceptibility pattern was determined using the Kirby-Bauer disk diffusion method and/or broth method [minimum inhibitory concentration (MIC)].RESULTS: The most common location of ulceration was the toe (54%), followed by the plantar surface (27%) and dorsal portion (19%). A total of 89 bacterial isolates were obtained from 30 patients. The infections were predominantly due to Gram-positive bacteria and polymicrobial bacteremia. The most commonly isolated Gram-positive bacteria were Staphylococcus aureus, followed by Staphylococcus saprophyticus, Staphylococcus epidermidis, Streptococcus agalactiae, and Streptococcus pneumoniae. The most commonly isolated Gram-negative bacteria were Proteus spp. and Enterobacterspp., followed by Escherichia coli, Pseudomonasspp., and Citrobacterspp. Nine cases of methicillin-resistant Staphylococcus aureus (MRSA) had cefoxitin resistance, and among these MRSA isolates, 3 were resistant to vancomycin with the MIC technique. The antibiotic imipenem was the most effective against both Gram-positive and Gram-negative bacteria, and gentamicin was effective against Gram-negative bacteria.CONCLUSIONS: The present study confirmed the high prevalence of multidrug-resistant pathogens in diabetic foot ulcers. It is necessary to evaluate the different microorganisms infecting the wound and to know the antibiotic susceptibility patterns of the isolates from the infected wound. This knowledge is crucial for planning treatment with the appropriate antibiotics, reducing resistance patterns, and minimizing healthcare costs.

Tree species diversity in a seasonally-dry forest: the case of the Pinkaití site, in the Kayapó Indigenous Area, Southeastern limits of the Amazon

This study investigates patterns of forest structure and tree species diversity in an anthropogenic palm grove and undisturbed areas at the seasonally-dry Pinkaití research station, in the Kayapó Indigenous Area. This site, managed by the Conservation International do Brasil, is the most southeastern site floristically surveyed in the Amazon until now. The secondary and a nearby undisturbed forest were sampled in a group of 52 floristic plots of 0.0625-ha (25x25-m) where all trees with DBH > 10 cm were measured and identified. The analyses were complemented with other two floristic plots of 1-ha (10x1000-m). The present study has shown that the Pinkaití, like other seasonally-dry forests, have great heterogeneity in forest structure and composition, associated with biotic characteristics of the most important tree species, natural disturbance and history of land-use. The palm grove, moderately dominated by the arborescent palm Attalea maripa (Aubl.) Mart., presented high tree species diversity and was floristically similar to undisturbed forests at the study site. It is discussed the importance of large arborescent palms for the seasonally-dry Amazon forests regeneration.

Fisheries and fishing effort at the Indigenous Reserves Ashaninka/Kaxinawá, river Breu, Brazil/Peru

This article aimed to describe the subsistence fisheries of traditional populations of three ethnic groups, one Ashaninka and two Kaxinawá, lying on the banks of the River Breu. Initially, monitors were trained to fill logbooks with data from fisheries of the villages during an annual cycle (august/1995 august/1996). Based on these data, it was realized an inventory of the most common fish species caught as well as one about the fishing environment. The following results were obtained: i) Indians prefer to use pools, locally known as "poços", for fishing; ii) the most common caught species are the "mandis" (35%, Pimelodidae), armored catfishes (Loricariidae), specially Hypostomus sp. (25%), the "curimatá" (9%, Prochilodus sp.) and the "saburus" (8%, Curimatidae), among others; iii) the fishing gears that lead to a high rate of fishing are the native "tingui", nets and bow and arrows; iv) fisheries are more intensive during summer; v) the fishing effort and their associated factors statistically significant in predicting the catches in the Indian Reserve were f1 = number of fishermen, f2 = (number of fishermen*total time devoted to fishing), f3 = [(number of fishermen)*(total time devoted to fishing)-(the time displacement)] and the factor villages and fishing gears; vi) although almost all the fisheries are done by walking to the fishing places, catches increase when paddle boats are used; and vii) the most active fishermen belong to Kaxinawá tribe.

Bacterial cellulose as a novel substrate for retinal pigment epithelium cells transplantation in age-related macular degeneration

Tese de Doutoramento em Engenharia Química e Biológica.

Epidemiological studies of Mansonella ozzardi (Nematoda, Onchocercidae) in indigenous communities of Pauini municipality, Amazonas, Brazil

The Mansonella ozzardi has a widespread distribution among the indigenous and riverine communities of Amazonas, Brazil. We estimated the prevalence of Mansonella ozzardi in indigenous communities of the Pauini municipality, Amazonas state, Brazil and the rate of parasitic infection in vectors. We collected thick blood smears from individuals from six Apurinã indigenous communities along the Purus River and its tributaries. Collections of simuliids were made and dissected, and the larval instars of M. ozzardi identified. The overall prevalence of M. ozzardi was 28.40%, with the highest incidence among males and agricultural workers. Among age groups, children 2-9 years of age had the lowest incidence, while individuals older than 58 exhibited the highest rates of infection. We found infected simuliids in three communities, with Parasitic Infection Rates (PIR) of 0.34-6.58%. The prevalence of M. ozzardi among the Apurinã people is high, possibly related to the diary activities of the riparian people, where a high abundance of the vectors exists.

The influence of biofilm formation by Gardnerella vaginalis and other anaerobes on bacterial vaginosis

Bacterial vaginosis (BV) is the worldwide leading vaginal disorder in women of reproductive age. BV is characterized by the replacement of beneficial lactobacilli and the augmentation of anaerobic bacteria. Gardnerella vaginalis is a predominant bacterial species, however, BV is also associated with other numerous anaerobes, such as Atopobium vaginae, Mobiluncus mulieris, Prevotella bivia, Fusobacterium nucleatum and Peptoniphilus sp.. Currently, the role of G. vaginalis in the etiology of BV remains a matter of controversy. It is however known that, in BV patients, a biofilm is usually formed on the vaginal epithelium and G. vaginalis is typically the predominant species. So, the current paradigm is that the establishment of a biofilm plays a key role in the pathogenesis of BV. This review provides background on the influence of biofilm formation by G. vaginalis and other anaerobes in the polymicrobial etiology of BV, through its initial adhesion until biofilm formation and discusses the commensal and synergic interactions established between them to understand the phenotypic shift of G. vaginalis' biofilms into BV establishment.

Engineering modular viral scaffolds for targeted bacterial population editing

Bacteria are central to human health and disease, but existing tools to edit microbial consortia are limited. For example, broad-spectrum antibiotics are unable to precisely manipulate bacterial communities. Bacteriophages can provide highly specific targeting of bacteria, but assembling well-defined phage cocktails solely with natural phages can be a time-, labor- and cost-intensive process. Here, we present a synthetic biology strategy to modulate phage host ranges by engineering phage genomes in Saccharomyces cerevisiae. We used this technology to redirect Escherichia coli phage scaffolds to target pathogenic Yersinia and Klebsiella bacteria, and conversely, Klebsiella phage scaffolds to target E. coli by modular swapping of phage tail components. The synthetic phages achieved efficient killing of their new target bacteria and were used to selectively remove bacteria from multi-species bacterial communities with cocktails based on common viral scaffolds. We envision this approach accelerating phage biology studies and enabling new technologies for bacterial population editing.