Evaluation of oxacillin and cefoxitin disks for detection of resistance in coagulase negative staphylococci

Coagulase-negative Staphylococcus spp. was considered nonpathogenic until the emergence of multiresistance and the demonstration of their participation as infectious agents. In Brazil, oxacillin resistance may be present in over 80% of isolates, and the Clinical and Laboratory Standards Institute standardized a disk-diffusion method to predict this resistance in Staphylococcus. The aim of this study was to evaluate the variability among commercial disks of oxacillin (1 µg) and cefoxitin (30 µg) widely used in clinical laboratories of microbiology, compared with mecA gene and minimum inhibitory concentration (MIC) of oxacillin. The use of oxacillin and cefoxitin disks simultaneously allowed the detection of important differences, particularly, in less frequent species such as S. cohnii, S. haemolyticus, S. saprophyticus, and S. sciuri. Disks of cefoxitin of the brand 2 displayed good correlation with the mecA gene (98.7%) and oxacillin MIC (97.8%), while major discrepancies were observed using disks of brand 1. One of the critical points in the diffusion disk test is the quality of the disks: the use of better quality disks associated with molecular methods lead to better results to define the best antibiotic therapy.

Recognition of the epidemiological significance of Neisseria meningitidis capsular serogroup W135 in the Rio de Janeiro region, Brazil

Neisseria meningitidis retains its ability to cause endemic and hiperendemic disease in human population living in any environment, as well as localized outbreaks and massive epidemics in civilians and military personnel. In Rio de Janeiro it has been reported in the 1990s as prolonged outbreak of serogroup B and at least one epidemic of serogroup C was well defined, both demanding quick action by the Public Health authorities. We report here the emergence of serogroup W135 meningococcal disease causing endemic and case cluster in Rio de Janeiro during the first years of this new century.

Hospitalization due to norovirus and genotypes of rotavirus in pediatric patients, state of Espírito Santo

Viruses are the leading cause for hospitalization due to gastroenteritis worldwide. Group A rotaviruses (RV) are the most prevalent and are assorted in glycoproteins (G) and protease sensitive (P) dual genotypes based on polymorphic genes that encode the external VP7 and VP4 capsid proteins, respectively. Noroviruses (NoV) have increasingly answered by sporadic gastroenteritis. This study aimed to determine the prevalence of NoV and RV in 68 hospitalized children, between July 2004 and November 2006, at a pediatric hospital in Vitória city, state of Espírito Santo, Southeastern Brazil. Nucleic acid was extracted from fecal suspension following the guanidine-silica procedure. Reverse transcriptase-polymerase chain reaction (RT-PCR) and polyacrylamide gel electrophoresis were employed for NoV and RV detection, respectively. RV genotyping was accomplished using RT-PCR followed by heminested multiplex PCR with specific primers for the most prevalent types of G and P. Fecal samples were positive for NoV and RV in 39.7% (27/68) and 20.5% (14/68), respectively and together were responsible for 60% (41/68) of the cases. RV genotypes were: 50% G9P[8], 28.7% G2P[4], 7.1% G1P[8], G2P[8] and G?P[8]. Vomit was a prominent manifestation observed in 92% and 85% of the NoV and RV cases, respectively. The median hospitalization was 5 and 5.5 days for the patients infected with NoV and RV, respectively. The data showed that NoV prevailed over RV and it also corroborated the emergence of RV G9 genotype followed by G2P[4], reinforcing the need for RV genotype surveillance.

Comparison of tests for the detection of circulating filarial antigen (Og4C3-ELISA and AD12-ICT) and ultrasound in diagnosis of lymphatic filariasis in individuals with microfilariae

Significant advances were made in the diagnosis of filariasis in the 1990s with the emergence of three new alternative tools: ultrasound and tests to detect circulating antigen using two monoclonal antibodies, Og4C3 and AD12-ICT-card. This study aimed to identify which of these methods is the most sensitive for diagnosis of infection. A total of 256 individuals, all male and carrying microfilariae (1-15,679 MF/mL), diagnosed by nocturnal venous blood samples, were tested by all three techniques. The tests for circulating filarial antigen concurred 100% and correctly identified 246/256 (96.69%) of the positive individuals, while ultrasound detected only 186/256 (73.44%). Of the circulating antigen tests, ICT-card was the most convenient method for identification of Wuchereria bancrofti carriers. It was easy to perform, practical and quick.

Occurrence and composition of class 1 and class 2 integrons in clinical and environmental O1 and non-O1/non-O139 Vibrio cholerae strains from the Brazilian Amazon

This study identified and characterised class 1 and 2 integrons in clinical and environmental Vibrio cholerae O1 and non-O1/non-O139 strains isolated from the Brazilian Amazon. The aadA2 and aadA7 gene cassettes were found in class 1 integrons in two genotypes of environmental V. cholerae non-O1/non-O139. Empty integrons were found in strains from the Brazilian cholera epidemic. A class 2 integron was detected in one strain from the V. cholerae Amazonia lineage harbouring sat1 and aadA1 genes. All isolates were resistant to aminoglycosides, indicating aadA functionality. These findings suggest that environmental bacteria act as cassette reservoirs that favour the emergence of resistant pathogens.

Current epidemiological status of schistosomiasis in the state of Pernambuco, Brazil

Uncontrolled peripheral urbanisation coupled with environmental degradation has affected the status of schistosomiasis in Pernambuco (PE), Brazil. This endemic disease continues to perpetuate its transmission in rural areas and has also become a cause for concern in coastal towns of the state. The lack of basic infrastructure (sanitation and health programmes) to support the new urban areas leads to faecal contamination of natural aquatic environments, resulting in consequent infection of vector snails and the emergence of new sources of schistosomiasis transmission. In the present paper, we discuss the current epidemiological status of schistosomiasis in PE. We have consolidated and analysed information from parasitological, malacological and morbidity surveys undertaken by the group of researchers at the Laboratory of Schistosomiasis, Centro de Pesquisas Aggeu Magalhães-Fiocruz. The results of our analysis show: (i) the maintenance of the levels of schistosomiasis in the rural Zona da Mata, PE, (ii) the record of the human cases of schistosomiasis and the foci of infected snails detected along the coast of PE through 2007, (iii) the high record of the severe clinical form of schistosomiasis in the metropolitan region of Recife (RMR) and (iv) new breeding sites of schistosomiasis vector snails that were identified in a 2008 survey covering the RMR and the coastal localities of PE.

Circulation of hantaviruses in the influence area of the Cuiabá-Santarém Highway

We describe evidence of circulation of hantaviruses in the influence area of the Santarém-Cuiabá Highway (BR-163) in the Brazilian Amazon through the prevalence of specific antibodies against hantaviruses in inhabitants living in four municipalities of this area: Novo Progresso (2.16%) and Trairão (4.37%), in state of Pará (PA), and Gua-rantã do Norte (4.74%) and Marcelândia (9.43%), in state of Mato Grosso. We also demonstrate the ongoing association between Castelo dos Sonhos virus (CASV) and hantavirus pulmonary syndrome (HPS) cases in the Castelo dos Sonhos district (municipality of Altamira, PA) and the first report of CASV in the municipalities of Novo Progresso and Guarantã do Norte. The results of this work highlight the risk for a possible increase in the number of HPS cases and the emergence of new hantavirus lineages associated with deforestation in this Amazonian area after the conclusion of paving works on BR-163 Highway.

Plasmodium falciparum gametocyte carriage, emergence, clearance and population sex ratios in anaemic and non-anaemic malarious children

Anaemia in falciparum malaria is associated with an increased risk of gametocyte carriage, but its effects on transmission have not been extensively evaluated in malarious children. Plasmodium falciparum gametocyte carriage, emergence, clearance, population sex ratios (SR) (defined as the proportion of gametocytes that are male), inbreeding rates and temporal changes in SR were evaluated in 840 malarious children. Gametocyte carriage pre-treatment was at a level of 8.1%. Anaemia at enrolment was an independent risk factor for gametocyte carriage post-treatment. The emergence of gametocytes seven days post-treatment was significantly more frequent in anaemic children (7/106 vs. 10/696, p = 0.002). In the initially detected gametocytes, the proportion of children with a male-biased SR (MBSR) (> 0.5) was significantly higher in anaemic children (6/7 vs. 3/10, p = 0.027). Pre-treatment SR and estimated inbreeding rates (proportion of a mother's daughters fertilised by her sons) were similar in anaemic and non-anaemic children. Pre-treatment SR became more female-biased in non-anaemic children following treatment. However, in anaemic children, SR became male-biased. Anaemia was shown to significantly increase gametocyte emergence and may significantly alter the SR of emerging gametocytes. If MBSR is more infective to mosquitoes at low gametocytaemia, then these findings may have significant implications for malaria control efforts in endemic settings where malaria-associated anaemia is common.

Chemoresistance of Plasmodium falciparum and Plasmodium vivax parasites in Brazil: consequences on disease morbidity and control

In Brazil, malaria still remains a clinically important febrile syndrome for local populations and travelers, occurring mostly in the Amazon Basin. This review aims to report the main efforts employed to control this disease since the 1940s and the emergence of Plasmodium falciparum and Plasmodium vivax chemoresistance to chloroquine and sulphadoxine-pyrimethamine among other drugs. Additionally, in vivo, in vitro and molecular studies as well as malaria chemoresistance consequences on disease morbidity and policy treatment guidelines were commented.

Treatment of an Aedes aegypti colony with the Cry11Aa toxin for 54 generations results in the development of resistance

To study the potential for the emergence of resistance in Aedes aegypti populations, a wild colony was subjected to selective pressure with Cry11Aa, one of four endotoxins that compose the Bacillus thuringiensis serovar israelensis toxin. This bacterium is the base component of the most important biopesticide used in the control of mosquitoes worldwide. After 54 generations of selection, significant resistance levels were observed. At the beginning of the selection experiment, the half lethal concentration was 26.3 ng/mL and had risen to 345.6 ng/mL by generation 54. The highest rate of resistance, 13.1, was detected in the 54th generation. Because digestive proteases play a key role in the processing and activation of B. thuringiensis toxin, we analysed the involvement of insect gut proteases in resistance to the Cry11Aa B. thuringiensis serovar israelensis toxin. The protease activity from larval gut extracts from the Cry11Aa resistant population was lower than that of the B. thuringiensisserovar israelensis susceptible colony. We suggest that differences in protoxin proteolysis could contribute to the resistance of this Ae. aegypti colony.

Influenza A virus infection of healthy piglets in an abattoir in Brazil: animal-human interface and risk for interspecies transmission

Asymptomatic influenza virus infections in pigs are frequent and the lack of measures for controlling viral spread facilitates the circulation of different virus strains between pigs. The goal of this study was to demonstrate the circulation of influenza A virus strains among asymptomatic piglets in an abattoir in Brazil and discuss the potential public health impacts. Tracheal samples (n = 330) were collected from asymptomatic animals by a veterinarian that also performed visual lung tissue examinations. No slaughtered animals presented with any noticeable macroscopic signs of influenza infection following examination of lung tissues. Samples were then analysed by reverse transcription-polymerase chain reaction that resulted in the identification of 30 (9%) influenza A positive samples. The presence of asymptomatic pig infections suggested that these animals could facilitate virus dissemination and act as a source of infection for the herd, thereby enabling the emergence of influenza outbreaks associated with significant economic losses. Furthermore, the continuous exposure of the farm and abattoir workers to the virus increases the risk for interspecies transmission. Monitoring measures of swine influenza virus infections and vaccination and monitoring of employees for influenza infection should also be considered. In addition regulatory agencies should consider the public health ramifications regarding the potential zoonotic viral transmission between humans and pigs.

Serologic survey of West Nile virus in horses from Central-West, Northeast and Southeast Brazil

Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country.

Evidence of an increased incidence of day 3 parasitaemia in Suriname: an indicator of the emerging resistance of Plasmodium falciparum to artemether

The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3 compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether.

The multifaceted resources and microevolution of the successful human and animal pathogen methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important bacterial pathogens based on its incidence and the severity of its associated infections. In addition, severe MRSA infections can occur in hospitalised patients or healthy individuals from the community. Studies have shown the infiltration of MRSA isolates of community origin into hospitals and variants of hospital-associated MRSA have caused infections in the community. These rapid epidemiological changes represent a challenge for the molecular characterisation of such bacteria as a hospital or community-acquired pathogen. To efficiently control the spread of MRSA, it is important to promptly detect the mecA gene, which is the determinant of methicillin resistance, using a polymerase chain reaction-based test or other rapidly and accurate methods that detect the mecA product penicillin-binding protein (PBP)2a or PBP2’. The recent emergence of MRSA isolates that harbour a mecA allotype, i.e., the mecC gene, infecting animals and humans has raised an additional and significant issue regarding MRSA laboratory detection. Antimicrobial drugs for MRSA therapy are becoming depleted and vancomycin is still the main choice in many cases. In this review, we present an overview of MRSA infections in community and healthcare settings with focus on recent changes in the global epidemiology, with special reference to the MRSA picture in Brazil.

Structure-based drug design studies of the interactions ofent-kaurane diterpenes derived from Wedelia paludosa with the Plasmodium falciparumsarco/endoplasmic reticulum Ca2+-ATPase PfATP6

Malaria is responsible for more deaths around the world than any other parasitic disease. Due to the emergence of strains that are resistant to the current chemotherapeutic antimalarial arsenal, the search for new antimalarial drugs remains urgent though hampered by a lack of knowledge regarding the molecular mechanisms of artemisinin resistance. Semisynthetic compounds derived from diterpenes from the medicinal plant Wedelia paludosawere tested in silico against the Plasmodium falciparumCa2+-ATPase, PfATP6. This protein was constructed by comparative modelling using the three-dimensional structure of a homologous protein, 1IWO, as a scaffold. Compound 21 showed the best docking scores, indicating a better interaction with PfATP6 than that of thapsigargin, the natural inhibitor. Inhibition of PfATP6 by diterpene compounds could promote a change in calcium homeostasis, leading to parasite death. These data suggest PfATP6 as a potential target for the antimalarial ent-kaurane diterpenes.