A spatial approach for the epidemiology of antibiotic use and resistance in community-based studies: the emergence of urban clusters of Escherichia coli quinolone resistance in Sao Paulo, Brasil

Copyright © Kiffer et al; licensee BioMed Central Ltd. 2011 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background Population antimicrobial use may influence resistance emergence. Resistance is an ecological phenomenon due to potential transmissibility. We investigated spatial and temporal patterns of ciprofloxacin (CIP) population consumption related to E. coli resistance emergence and dissemination in a major Brazilian city. A total of 4,372 urinary tract infection E. coli cases, with 723 CIP resistant, were identified in 2002 from two outpatient centres. Cases were address geocoded in a digital map. Raw CIP consumption data was transformed into usage density in DDDs by CIP selling points influence zones determination. A stochastic model coupled with a Geographical Information System was applied for relating resistance and usage density and for detecting city areas of high/low resistance risk. Results E. coli CIP resistant cluster emergence was detected and significantly related to usage density at a level of 5 to 9 CIP DDDs. There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. Conclusions There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. The usage density of 5-9 CIP DDDs per 1,000 inhabitants within the same influence zone was the resistance triggering level. This level led to E. coli resistance clustering, proving that individual resistance emergence and dissemination was affected by antimicrobial population consumption

Discrepant Prevalence and Incidence of Leishmania Infection between Two Neighboring Villages in Central Mali Based on Leishmanin Skin Test Surveys

Leishmaniasis is a vector-borne disease transmitted to humans by the bite of an infected sand fly. Leishmaniasis is present in more than 88 countries and affects more than 12 million people. Depending on the species of Leishmania, the host can develop cutaneous leishmaniasis (CL), which is characterized by skin ulcers in uncovered parts of the body or a more severe form, visceral leishmaniasis, which affects the liver and spleen and is fatal if not treated. This study aims to establish the past and present infection with Leishmania parasites in two villages where recent cases have been diagnosed by the dermatology center (CNAM) in Bamako. This was achieved using a Leishmania-specific skin test that was administered annually to permanent residents of Kemena and Sougoula villages from 2006 to 2008. The results show that transmission of Leishmania is active and stable in these two villages. Moreover, despite sharing similar cultural and environmental features, the individuals from Kemena presented three times the risk of Leishmania infection compared with those from Sougoula. Our findings raise awareness of the continued presence of CL in Mali

Screening of Tanzanian medicinal plants for anti-Candida activity

BACKGROUND: Candida albicans has become resistant to the already limited, toxic and expensive anti-Candida agents available in the market. These factors necessitate the search for new anti-fungal agents. METHODS: Sixty-three plant extracts, from 56 Tanzanian plant species obtained through the literature and interviews with traditional healers, were evaluated for anti-Candida activity. Aqueous methanolic extracts were screened for anti-Candida activity by bioautography agar overlay method, using a standard strain of Candida albicans (ATCC 90028). RESULTS: Twenty- seven (48%) out of the 56 plants were found to be active. Extracts of the root barks of Albizia anthelmintica and Balanites aegyptiaca, and roots of Plectranthus barbatus showed strong activity. CONCLUSION: The extracts that showed strong anti-Candida activity are worth of further investigation in order to isolate and identify the active compounds

Distribution and seasonality of rhinovirus and other respiratory viruses in a cross-section of asthmatic children in Trinidad, West Indies

<p>Abstract</p> <p>Background</p> <p>Childhood asthma in the Caribbean is advancing in prevalence and morbidity. Though viral respiratory tract infections are reported triggers for exacerbations, information on these infections with asthma is sparse in Caribbean territories. We examined the distribution of respiratory viruses and their association with seasons in acute and stable asthmatic children in Trinidad.</p> <p>Methods</p> <p>In a cross-sectional study of 70 wheezing children attending the emergency department for nebulisation and 80 stable control subjects (2 to 16 yr of age) in the asthma clinic, nasal specimens were collected during the dry (<it>n </it>= 38, January to May) and rainy (<it>n </it>= 112, June to December) seasons. A multitarget, sensitive, specific high-throughput Respiratory MultiCode assay tested for respiratory-virus sequences for eight distinct groups: human rhinovirus, respiratory syncytial virus, parainfluenza virus, influenza virus, metapneumovirus, adenovirus, coronavirus, and enterovirus.</p> <p>Results</p> <p>Wheezing children had a higher [χ²= 5.561, <it>p </it>= 0.018] prevalence of respiratory viruses compared with stabilized asthmatics (34.3% (24) versus (vs.) 17.5% (14)). Acute asthmatics were thrice as likely to be infected with a respiratory virus (OR = 2.5, 95% CI = 1.2 – 5.3). The predominant pathogens detected in acute versus stable asthmatics were the rhinovirus (RV) (<it>n </it>= 18, 25.7% vs. <it>n </it>= 7, 8.8%; <it>p </it>= 0.005), respiratory syncytial virus B (RSV B) (<it>n </it>= 2, 2.9% vs. <it>n </it>= 4, 5.0%), and enterovirus (<it>n </it>= 1, 1.4% vs. <it>n </it>= 2, 2.5%). Strong odds for rhinoviral infection were observed among nebulised children compared with stable asthmatics (<it>p </it>= 0.005, OR = 3.6, 95% CI = 1.4 – 9.3,). RV was prevalent throughout the year (Dry, <it>n </it>= 6, 15.8%; Rainy, <it>n </it>= 19, 17.0%) and without seasonal association [χ²= 0.028, <it>p </it>= 0.867]. However it was the most frequently detected virus [Dry = 6/10, (60.0%); Rainy = 19/28, (67.9%)] in both seasons.</p> <p>Conclusion</p> <p>Emergent wheezing illnesses during childhood can be linked to infection with rhinovirus in Trinidad's tropical environment. Viral-induced exacerbations of asthma are independent of seasons in this tropical climate. Further clinical and virology investigations are recommended on the role of infections with the rhinovirus in Caribbean childhood wheeze.</p

Cell Size and the Initiation of DNA Replication in Bacteria

In eukaryotes, DNA replication is coupled to the cell cycle through the actions of cyclin-dependent kinases and associated factors. In bacteria, the prevailing view, based primarily from work in Escherichia coli, is that growth-dependent accumulation of the highly conserved initiator, DnaA, triggers initiation. However, the timing of initiation is unchanged in Bacillus subtilis mutants that are ∼30% smaller than wild-type cells, indicating that achievement of a particular cell size is not obligatory for initiation. Prompted by this finding, we re-examined the link between cell size and initiation in both E. coli and B. subtilis. Although changes in DNA replication have been shown to alter both E. coli and B. subtilis cell size, the converse (the effect of cell size on DNA replication) has not been explored. Here, we report that the mechanisms responsible for coordinating DNA replication with cell size vary between these two model organisms. In contrast to B. subtilis, small E. coli mutants delayed replication initiation until they achieved the size at which wild-type cells initiate. Modest increases in DnaA alleviated the delay, supporting the view that growth-dependent accumulation of DnaA is the trigger for replication initiation in E. coli. Significantly, although small E. coli and B. subtilis cells both maintained wild-type concentration of DnaA, only the E. coli mutants failed to initiate on time. Thus, rather than the concentration, the total amount of DnaA appears to be more important for initiation timing in E. coli. The difference in behavior of the two bacteria appears to lie in the mechanisms that control the activity of DnaA

Phylogeography and Population Structure of Glossina fuscipes fuscipes in Uganda: Implications for Control of Tsetse

Glossina fuscipes fuscipes is the most common species of tsetse in Uganda, where it transmits human sleeping sickness and nagana, a related disease of cattle. A consortium of African countries dedicated to controlling these diseases is poised to begin area wide control of tsetse, but a critical question remains: What is the most appropriate geographical scale for these activities? To address this question, we used population genetics to determine the extent of linkage between populations of tsetse confined to discrete patches of riverine habitat. Our results suggest that Uganda was colonized by two distinct lineages of G. f. fuscipes, which now co-occur only in a narrow band across central Uganda. Evidence for interbreeding at the zone of contact and movement of genes from the south to the north suggest that this historical genetic structure may dissolve in the future. At smaller scales, we have demonstrated that exchange of genes among neighboring populations via dispersal is at equilibrium with the differentiating force of genetic drift. Our results highlight the need for investment in vector control programs that account for the linkage observed among tsetse populations. Given its genetic isolation and its location at the far edge of G. fuscipes' range, the Lake Victoria region appears to be an appropriate target for area wide control

The Influence of Spatial Registration on Detection of Cerebral Asymmetries Using Voxel-Based Statistics of Fractional Anisotropy Images and TBSS

The sensitivity of diffusion tensor imaging (DTI) for detecting microstructural white matter alterations has motivated the application of voxel-based statistics (VBS) to fractional anisotropy (FA) images (FA-VBS). However, detected group differences may depend on the spatial registration method used. The objective of this study was to investigate the influence of spatial registration on detecting cerebral asymmetries in FA-VBS analyses with reference to data obtained using Tract-Based Spatial Statistics (TBSS). In the first part of this study we performed FA-VBS analyses using three single-contrast and one multi-contrast registration: (i) whole-brain registration based on T2 contrast, (ii) whole-brain registration based on FA contrast, (iii) individual-hemisphere registration based on FA contrast, and (iv) a combination of (i) and (iii). We then compared the FA-VBS results with those obtained from TBSS. We found that the FA-VBS results depended strongly on the employed registration approach, with the best correspondence between FA-VBS and TBSS results when approach (iv), the “multi-contrast individual-hemisphere” method was employed. In the second part of the study, we investigated the spatial distribution of residual misregistration for each registration approach and the effect on FA-VBS results. For the FA-VBS analyses using the three single-contrast registration methods, we identified FA asymmetries that were (a) located in regions prone to misregistrations, (b) not detected by TBSS, and (c) specific to the applied registration approach. These asymmetries were considered candidates for apparent FA asymmetries due to systematic misregistrations associated with the FA-VBS approach. Finally, we demonstrated that the “multi-contrast individual-hemisphere” approach showed the least residual spatial misregistrations and thus might be most appropriate for cerebral FA-VBS analyses