Neotropical Entomology 34(6): 999-1006 (2005) Formigas Como Agentes Carreadores de Bactérias Resistentes em Hospitais RESUMO -A presença de bactérias resistentes a antimicrobianos e carreadas por formigas isoladas em hospitais foi investigada em Campos dos Goytacazes, RJ. Três instituições de saúde foram visitadas nos períodos de 2001 a 2002 e amostras foram coletadas em áreas de cuidados médicos consideradas críticas baseando-se em critérios de maior risco para a aquisição de infecções por pacientes hospitalizados. Quatro espécies de formigas foram identificadas, Tapinoma melanocephalum (Fabricius) (63,1%), Paratrechina longicornis (Latreille) (21,1%), Monomorium pharaonis (L.) (10,5%) e Solenopsis saevissima (S. Smith) (5,3%) como carreadoras de 21 morfoespécies de bactérias. Os testes de identificação bacteriana e de perfil de resistência antimicrobiana foram realizados por meio de kits padronizados e avaliados por método automatizado. Entre as bactérias isoladas, algumas foram consideradas multirresistentes, incluindo o gênero Acinetobacter, Streptococcus, Gemella, e Klebsiella. Para análise antimicrobiana do gênero Enterobacter foi utilizado o método padrão de difusão em disco. Os resultados sugerem que existem riscos para pacientes que procuram por assistência de saúde nos hospitais estudados e a ocorrência de bactérias emergentes em hospitais carreadas por formigas devem ser consideradas. PALAVRAS-CHAVE: Infecçcão nosocomial, antimicrobiano, controle, formiga urbana ABSTRACT -The presence of antimicrobial-resistant bacteria and carried by ants isolated from hospitals was investigated in Campos dos Goytacazes, RJ, Brazil. Three health institutions were visited from 2001 to 2002 and samples were collected within critical areas of medical care based on criteria of greater risk of patient hospital acquired-infection. Four ant species were identified, Tapinoma melanocephalum (Fabricius) (63.1%), Paratrechina longicornis (Latreille) (21.1%), Monomorium pharaonis (L.) (10.5%), and Solenopsis saevissima (S. Smith) (5.3%) carrying 21 species of bacteria. The tests for bacteria species identification and antimicrobial-resistance profile were carried out by using standardized kits and evaluated by automated equipment. Among the bacteria isolates, some were considered multiresistant isolates, including genera Acinetobacter, Streptococcus, Gemella, and Klebsiella. For Enterobacter antibacterial analysis the disk diffusion standard method was used. The results suggest that there are risks for patients which seek for health assistance in the hospitals studied, and the presence of emerging bacteria isolates in hospital carried by ants must be considered.

Although only discovered in 1999, the symbiotic filamentous actinobacteria present on the integument of certain species of leaf-cutting ants have been the subject of intense research. These bacteria have been shown to specifically suppress fungal garden parasites by secretion of antibiotics. However, more recently, a wider role for these bacteria has been suggested from research revealing their generalist anti-fungal activity. Here we show, for the first time, evidence for a role of these bacteria in the defence of young worker ants against a fungal entomopathogen. Experimental removal of the bacterial bio-film using an antibiotic resulted in a significant increase in susceptibility of worker ants to infection by the entomopathogenic fungus Metarhizium anisopliae . This is the first direct evidence for the advantage of maintaining a bacterial bio-film on the cuticle as a defensive strategy of the ants themselves and not exclusively for protection of the fungus garden.

Alzheimeŕs disease (AD) represents the most prevalent neurodegenerative disorder that causes cognitive decline in old age. In its early stages, AD is associated with microstructural abnormalities in white matter (WM). In the current study, multiple indices of diffusion tensor imaging (DTI) and brain volumetric measurements were employed to comprehensively investigate the landscape of AD pathology. The sample comprised 58 individuals including cognitively normal subjects (controls), amnestic mild cognitive impairment (MCI) and AD patients. Relative to controls, both MCI and AD subjects showed widespread changes of anisotropic fraction (FA) in the corpus callosum, cingulate and uncinate fasciculus. Mean diffusivity and radial changes were also observed in AD patients in comparison with controls. After controlling for the gray matter atrophy the number of regions of significantly lower FA in AD patients relative to controls was decreased; nonetheless, unique areas of microstructural damage remained, e.g., the corpus callosum and uncinate fasciculus. Despite sample size limitations, the current results suggest that a combination of secondary and primary degeneration occurrs in MCI and AD, although the secondary degeneration appears to have a more critical role during the stages of disease involving dementia.

Neotropical Entomology 31(2): 241-244 (2002) ABSTRACT -The leaf-cutting ants Atta sexdens (L.) and Atta laevigata (Smith) constitute serious pests of agriculture and forestry in Brazil. These ants are parasitized by the phorids Neodohrniphora tonhascai Brown and Neodohrniphora erthali Brown (Diptera: Phoridae), respectively. The parasitic potential of N. tonhascai against its host has been previously investigated, but no equivalent information is available for N. erthali. The objectives of this study were to evaluate the oviposition behavior and some biological characteristics of N. erthali in relation to its host and to determine the parasitic potential of N. tonhascai against A. laevigata, considering that in many parts of southeastern Brazil nests of A. sexdens and A. laevigata are found in close proximity of each other. These data were obtained from female N. erthali and N. tonhascai collected in the field in Viçosa (Minas Gerais State) and released singly in an observation chamber placed between a laboratory nest of A. laevigata and its foraging arena. Neodohrniphora tonhascai took less time selecting its hosts, attacked more ants and had greater rate of parasitism in relation to N. erthali. We could not establish whether A. laevigata is parasitized by N. tonhascai in the field, but the reproductive success of N. tonhascai in the laboratory demonstrated that A. laevigata is a suitable host to this parasitoid. The types of defense displayed by A. laevigata against both phorid species were markedly different, and these results suggest that foragers take specific defensive steps in order to reduce the possibility of parasitism by phorid flies.KEY WORDS: Attini, Neodohrniphora tonhascai, Neodohrniphora erthali, parasitoid, biological control. 242Bragança et al.Throughout most of their range, Atta spp. leaf-cutting ants are parasitized by flies of the genus Neodohrniphora (Diptera: Phoridae) (Prado 1976, Disney 1994, Brown 2001. These flies pursue and attack the larger foragers walking along trails, but nearby ants are also disturbed by flies' attacking bouts. Neodohrniphora have been implicated in the diel shift of foraging activity exhibited by Atta cephalotes (L.) (Orr 1992, Feener & Brown 1993 and in the reduction of the forager force size of Atta sexdens (L.) (Bragança et al. 1998, Tonhasca & Bragança 2000. When exposed to a Neodohrniphora species, young A. sexdens colonies (less than 1-year old) stop completely their foraging activity within five minutes of initial contact with the parasitoids (D.D.O. Moreira, unpubl.). In older colonies, A. sexdens foragers react to the presence of these flies by abandoning their loads and returning to the nest (Bragança et al. 1998). Consequently, the occurrence of Neodohrniphora represents a disruptive factor in the foraging of Atta leaf-cutting ants.Atta sexdens and Atta laevigata (Smith) are two of the most common leaf-cutting ants in Brazil, and both represent serious pests of agriculture and forestry (Fowler et al. 1989 Tonhasca (1996), where it was incorrectly n...