Application of four molecular typing methods for analysis of Mycobacterium fortuitum group strains causing post-mammaplasty infections

A cluster of cases of post-augmentation mammaplasty surgical site infections occurred between 2002 and 2004 in Campinas, in the southern region of Brazil. Rapidly growing mycobacteria were isolated from samples from 12 patients. Eleven isolates were identified as Mycobacterium fortuitum and one as Mycobacterium porcinum by PCR-restriction digestion of the hsp65 gene. These 12 isolates, plus six additional M. fortuitum isolates from non-related patients, were typed by pulsed-field gel electrophoresis (PFGE) and three PCR-based techniques: 16S-23S rRNA internal transcribed spacer (ITS) genotyping; randomly amplified polymorphic DNA (RAPD) PCR; and enterobacterial repetitive intergenic consensus (ERIC) PCR. Four novel M. fortuitum allelic variants were identified by restriction analysis of the ITS fragment. One major cluster, comprising six M. fortuitum isolates, and a second cluster of two isolates, were identified by the four methods. RAPD-PCR and ITS genotyping were less discriminative than ERIC-PCR. ERIC-PCR was comparable to PFGE as a valuable complementary tool for investigation of this type of outbreak.Universidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, SP, BrazilFleury Ctr Med Diagnost, São Paulo, BrazilInst Adolfo Lutz Registro, São Paulo, BrazilInst Vozza Med & Diagnose LTDA, Campinas, BrazilCtr Vigilancia Epidemiol Prof Alexandre Vranjac, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, SP, BrazilWeb of Scienc

Cooperation between Apoptotic and Viable Metacyclics Enhances the Pathogenesis of Leishmaniasis

Mimicking mammalian apoptotic cells by exposing phosphatidylserine (PS) is a strategy used by virus and parasitic protozoa to escape host protective inflammatory responses. With Leishmania amazonensis (La), apoptotic mimicry is a prerogative of the intramacrophagic amastigote form of the parasite and is modulated by the host. Now we show that differently from what happens with amastigotes, promastigotes exposing PS are non-viable, non-infective cells, undergoing apoptotic death. As part of the normal metacyclogenic process occurring in axenic cultures and in the gut of sand fly vectors, a sub-population of metacyclic promastigotes exposes PS. Apoptotic death of the purified PS-positive (PSPOS) sub-population was confirmed by TUNEL staining and DNA laddering. Transmission electron microscopy revealed morphological alterations in PSPOS metacyclics such as DNA condensation, cytoplasm degradation and mitochondrion and kinetoplast destruction, both in in vitro cultures and in sand fly guts. TUNELPOS promastigotes were detected only in the anterior midgut to foregut boundary of infected sand flies. Interestingly, caspase inhibitors modulated parasite death and PS exposure, when added to parasite cultures in a specific time window. Efficient in vitro macrophage infections and in vivo lesions only occur when PSPOS and PS-negative (PSNEG) parasites were simultaneously added to the cell culture or inoculated in the mammalian host. The viable PSNEG promastigote was the infective form, as shown by following the fate of fluorescently labeled parasites, while the PSPOS apoptotic sub-population inhibited host macrophage inflammatory response. PS exposure and macrophage inhibition by a subpopulation of promastigotes is a different mechanism than the one previously described with amastigotes, where the entire population exposes PS. Both mechanisms co-exist and play a role in the transmission and development of the disease in case of infection by La. Since both processes confer selective advantages to the infective microorganism they justify the occurrence of apoptotic features in a unicellular pathogen

Biased-corrected richness estimates for the Amazonian tree flora

Amazonian forests are extraordinarily diverse, but the estimated species richness is very much debated. Here, we apply an ensemble of parametric estimators and a novel technique that includes conspecific spatial aggregation to an extended database of forest plots with up-to-date taxonomy. We show that the species abundance distribution of Amazonia is best approximated by a logseries with aggregated individuals, where aggregation increases with rarity. By averaging several methods to estimate total richness, we confirm that over 15,000 tree species are expected to occur in Amazonia. We also show that using ten times the number of plots would result in an increase to just ~50% of those 15,000 estimated species. To get a more complete sample of all tree species, rigorous field campaigns may be needed but the number of trees in Amazonia will remain an estimate for years to come