Intraspecific variation in immune gene expression and heritable symbiont density.

Host genetic variation plays an important role in the structure and function of heritable microbial communities. Recent studies have shown that insects use immune mechanisms to regulate heritable symbionts. Here we test the hypothesis that variation in symbiont density among hosts is linked to intraspecific differences in the immune response to harboring symbionts. We show that pea aphids (Acyrthosiphon pisum) harboring the bacterial endosymbiont Regiella insecticola (but not all other species of symbionts) downregulate expression of key immune genes. We then functionally link immune expression with symbiont density using RNAi. The pea aphid species complex is comprised of multiple reproductively-isolated host plant-adapted populations. These 'biotypes' have distinct patterns of symbiont infections: for example, aphids from the Trifolium biotype are strongly associated with Regiella. Using RNAseq, we compare patterns of gene expression in response to Regiella in aphid genotypes from multiple biotypes, and we show that Trifolium aphids experience no downregulation of immune gene expression while hosting Regiella and harbor symbionts at lower densities. Using F1 hybrids between two biotypes, we find that symbiont density and immune gene expression are both intermediate in hybrids. We propose that in this system, Regiella symbionts are suppressing aphid immune mechanisms to increase their density, but that some hosts have adapted to prevent immune suppression in order to control symbiont numbers. This work therefore suggests that antagonistic coevolution can play a role in host-microbe interactions even when symbionts are transmitted vertically and provide a clear benefit to their hosts. The specific immune mechanisms that we find are downregulated in the presence of Regiella have been previously shown to combat pathogens in aphids, and thus this work also highlights the immune system's complex dual role in interacting with both beneficial and harmful microbes.

Predicting microbial growth dynamics in response to nutrient availability.

Developing mathematical models to accurately predict microbial growth dynamics remains a key challenge in ecology, evolution, biotechnology, and public health. To reproduce and grow, microbes need to take up essential nutrients from the environment, and mathematical models classically assume that the nutrient uptake rate is a saturating function of the nutrient concentration. In nature, microbes experience different levels of nutrient availability at all environmental scales, yet parameters shaping the nutrient uptake function are commonly estimated for a single initial nutrient concentration. This hampers the models from accurately capturing microbial dynamics when the environmental conditions change. To address this problem, we conduct growth experiments for a range of micro-organisms, including human fungal pathogens, baker's yeast, and common coliform bacteria, and uncover the following patterns. We observed that the maximal nutrient uptake rate and biomass yield were both decreasing functions of initial nutrient concentration. While a functional form for the relationship between biomass yield and initial nutrient concentration has been previously derived from first metabolic principles, here we also derive the form of the relationship between maximal nutrient uptake rate and initial nutrient concentration. Incorporating these two functions into a model of microbial growth allows for variable growth parameters and enables us to substantially improve predictions for microbial dynamics in a range of initial nutrient concentrations, compared to keeping growth parameters fixed.

Genomic characterization of an emerging Enterobacteriaceae species: the first case of co-infection with a typical pathogen in a human patient.

BACKGROUND: Opportunistic pathogens are important for clinical practice as they often cause antibiotic-resistant infections. However, little is documented for many emerging opportunistic pathogens and their biological characteristics. Here, we isolated a strain of extended-spectrum ß-lactamase-producing Enterobacteriaceae from a patient with a biliary tract infection. We explored the biological and genomic characteristics of this strain to provide new evidence and detailed information for opportunistic pathogens about the co-infection they may cause. RESULTS: The isolate grew very slowly but conferred strong protection for the co-infected cephalosporin-sensitive Klebsiella pneumoniae. As the initial laboratory testing failed to identify the taxonomy of the strain, great perplexity was caused in the etiological diagnosis and anti-infection treatment for the patient. Rigorous sequencing efforts achieved the complete genome sequence of the isolate which we designated as AF18. AF18 is phylogenetically close to a few strains isolated from soil, clinical sewage, and patients, forming a novel species together, while the taxonomic nomenclature of which is still under discussion. And this is the first report of human infection of this novel species. Like its relatives, AF18 harbors many genes related to cell mobility, various genes adaptive to both the natural environment and animal host, over 30 mobile genetic elements, and a plasmid bearing blaCTX-M-3 gene, indicating its ability to disseminate antimicrobial-resistant genes from the natural environment to patients. Transcriptome sequencing identified two sRNAs that critically regulate the growth rate of AF18, which could serve as targets for novel antimicrobial strategies. CONCLUSIONS: Our findings imply that AF18 and its species are not only infection-relevant but also potential disseminators of antibiotic resistance genes, which highlights the need for continuous monitoring for this novel species and efforts to develop treatment strategies.

[Microbiological testing of flexible endoscopes: contribution of the approach of accreditation in the implementation of regulation]. / Analyse microbiologique des solutions de contrôle d'endoscope : apport de la démarche d'accréditation dans la mise en application de la réglementation.

The microbiological surveillance of flexible endoscopes reprocessing involves counts of the mesophilic total aerobic revivable flora and the detection of indicator microorganisms of dysfunction. We presented the assay at the COFRAC certification, to ensure a maximal level of confidence in the quality of our results. The existing quality system management was used by the type B widened flexible scope for data from previous accreditations for the identification of Staphylococcus aureus, Enterococci and Enterobacteriaceae. The quality insurance of the results and the technical authorization were guaranteed by the participation at a program of interlaboratory comparisons and the elaboration of internal quality controls. Risks analyses and conventions were wrote with endoscopy sectors. The visit led the opening of a single and not critical deviation sheet on the control of consumables and the accreditation for the analysis was pronounced.

High intensity light pulses to reduce microbial load in fresh cheese.

The present study focused on the utilisation of High Intensity Light Pulses (HILP) treatment to preserve mozzarella cheese. First, the susceptibility of Pseudomonas fluorescens and Enterobacteriaceae to HILP (fluences from 0·39 to 28·0 J/cm2) in a transparent liquid was evaluated (in-vitro tests). Afterwards, the effects on inoculated mozzarella cheese were also assessed. Then untreated (Control) and HILP treated samples were packaged and stored at 10 °C for 2 weeks. Enterobacteriaceae, Pseudomonas spp. and pH were monitored during storage. In a transparent liquid (in-vitro tests) there was a significant microbial inactivation just with 2 s of treatment. On the inoculated cheese a relevant microbial reduction of about 1 log cycle was observed, according to the exposure to the treatments. For Pseudomonas spp. in particular, in the treated samples, the microbiological acceptability limit (106 cfu/g) was never reached after 2 weeks of refrigerated storage. To sum up, the efficacy of this treatment is very interesting because a microbial reduction was observed in treated samples. HILP treatment is able to control the microbial growth and may be considered a promising way to decontaminate the surface of mozzarella cheese.

Cryptosporidium and Giardia removal by secondary and tertiary wastewater treatment.

Wastewater disposal may be a source of environmental contamination by Cryptosporidium and Giardia. This study was conducted to evaluate the prevalence of Cryptosporidium oocysts and Giardia cysts in raw and treated wastewater effluents. A prevalence of 100% was demonstrated for Giardia cysts in raw wastewater, at a concentration range of 10 to 12,225 cysts L(-1), whereas the concentration of Cryptosporidium oocysts in raw wastewater was 4 to 125 oocysts L(-1). The removal of Giardia cysts by secondary and tertiary treatment processes was greater than those observed for Cryptosporidium oocysts and turbidity. Cryptosporidium and Giardia were present in 68.5% and 76% of the tertiary effluent samples, respectively, at an average concentration of 0.93 cysts L(-1) and 9.94 oocysts L(-1). A higher detection limit of Cryptosporidium oocysts in wastewater was observed for nested PCR as compared to immune fluorescent assay (IFA). C. hominis was found to be the dominant genotype in wastewater effluents followed by C. parvum and C. andersoni or C. muris. Giardia was more prevalent than Cryptosporidium in the studied community and treatment processes were more efficient for the removal of Giardia than Cryptosporidium. Zoonotic genotypes of Cryptosporidium were also present in the human community. To assess the public health significance of Cryptosporidium oocysts present in tertiary effluent, viability (infectivity) needs to be assessed.

Chemically defined diet alters the protective properties of fructo-oligosaccharides and isomalto-oligosaccharides in HLA-B27 transgenic rats.

Non-digestible oligosaccharides (NDO) were shown to reduce inflammation in experimental colitis, but it remains unclear whether microbiota changes mediate their colitis-modulating effects. This study assessed intestinal microbiota and intestinal inflammation after feeding chemically defined AIN-76A or rat chow diets, with or without supplementation with 8 g/kg body weight of fructo-oligosaccharides (FOS) or isomalto-oligosaccharides (IMO). The study used HLA-B27 transgenic rats, a validated model of inflammatory bowel disease (IBD), in a factorial design with 6 treatment groups. Intestinal inflammation and intestinal microbiota were analysed after 12 weeks of treatment. FOS and IMO reduced colitis in animals fed rat chow, but exhibited no anti-inflammatory effect when added to AIN-76A diets. Both NDO induced specific but divergent microbiota changes. Bifidobacteria and Enterobacteriaceae were stimulated by FOS, whereas copy numbers of Clostridium cluster IV were decreased. In addition, higher concentrations of total short-chain fatty acids (SCFA) were observed in cecal contents of rats on rat chow compared to the chemically defined diet. AIN-76A increased the relative proportions of propionate, iso-butyrate, valerate and iso-valerate irrespective of the oligosaccharide treatment. The SCFA composition, particularly the relative concentration of iso-butyrate, valerate and iso-valerate, was associated (P ≤ 0.004 and r ≥ 0.4) with increased colitis and IL-1 ß concentration of the cecal mucosa. This study demonstrated that the protective effects of fibres on colitis development depend on the diet. Although diets modified specific cecal microbiota, our study indicates that these changes were not associated with colitis reduction. Intestinal inflammation was positively correlated to protein fermentation and negatively correlated with carbohydrate fermentation in the large intestine.

Characterization of Raoultella planticola Rs-2 microcapsule prepared with a blend of alginate and starch and its release behavior.

To judiciously use Raoultella planticola Rs-2 and develop its biodegradable and controlled-release formulations, Rs-2 was encapsulated with various combinations of sodium alginate (NaAlg) and starch. Sodium alginate, soluble starch, and CaCl2 showed good biocompatibility with Rs-2 for preparing microcapsules. These microcapsules were spherical in shape and their particle size, embedding rate, swelling ratio of Rs-2 microcapsules and release numbers of viable Rs-2 cells increased with the increasing of starch and NaAlg concentrations. Meanwhile, the biodegradability of the microcapsules constantly increases when the wt% of starch increased, but decreased when the amount of NaAlg increased. In addition, the release mechanism of microcapsules was consistent with that of the Ritger-Peppas model, which involves the Case II diffusion mechanism. In summary, the desired properties of the microcapsules can be modulated by varying the starch and alginate amounts of capsule materials. This process has broad application prospects to meet the needs of agricultural production.

Dynamic interplay between the periplasmic and transmembrane domains of GspL and GspM in the type II secretion system.

The type II secretion system (T2SS) is a multiprotein nanomachine that transports folded proteins across the outer membrane of gram-negative bacteria. The molecular mechanisms that govern the secretion process remain poorly understood. The inner membrane components GspC, GspL and GspM possess a single transmembrane segment (TMS) and a large periplasmic region and they are thought to form a platform of unknown function. Here, using two-hybrid and pull-down assays we performed a systematic mapping of the GspC/GspL/GspM interaction regions in the plant pathogen Dickeya dadantii. We found that the TMS of these components interact with each other, implying a complex interaction network within the inner membrane. We also showed that the periplasmic, ferredoxin-like, domains of GspL and GspM drive homo- and heterodimerizations of these proteins. Disulfide bonding analyses revealed that the respective domain interfaces include the equivalent secondary-structure elements, suggesting alternating interactions of the periplasmic domains, L/L and M/M versus L/M. Finally, we found that displacements of the periplasmic GspM domain mediate coordinated shifts or rotations of the cognate TMS. These data suggest a plausible mechanism for signal transmission between the periplasmic and the cytoplasmic portions of the T2SS machine.

Polymerase chain reaction amplification length-dependent ethidium monoazide suppression power for heat-killed cells of Enterobacteriaceae.

The polymerase chain reaction (PCR) can confirm the presence of bacteria, but it is unable to differentiate between live and dead bacteria. Although ethidium monoazide (EMA)- and propidium monoazide (PMA)-based PCR have been evaluated, a quantity of ≥ 10(3)cells/ml dead cells produces a false-positive reading at 40 to 50 cycles (K. Rudi et al., Appl. Environ. Microbiol. 71 (2005) 1018-1024). After confirming the precision of real-time PCR of a long DNA target (16S or 23S ribosomal RNA [rRNA] gene, 1490 or 2840 bp), we evaluated the degree of suppression of an EMA treatment on the 16S/23S PCR using various amplification lengths (110-2840 bp) with heat-killed cells of Enterobacteriaceae (e.g., Salmonella enteritidis). We found that the inhibition rate was proportional to the PCR amplification length; short DNA (110 bp) amplification slightly delayed the threshold cycle (C(T)) of heat-killed cells of Enterobacteriaceae when compared with no EMA treatment. Regardless of the amplification length, the C(T) delay using live cells of Enterobacteriaceae with EMA was negligible. Thus, our real-time PCR of a long DNA (16S or 23S) template following EMA treatment is a rapid viable bacterial assay, which can potentially target all genera, for testing pasteurized milk that may have originally been contaminated with high levels of dead bacteria.

Phenotypic detection of broad-spectrum beta-lactamases in microbiological practice.

BACKGROUND: Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality. Their routine detection in microbiology laboratories is still a problem. The aim of this study was to compare the sensitivity of selected phenotypic methods. MATERIAL/METHODS: A total of 106 strains of the Enterobacteriaceae family were tested, in which molecular biology methods confirmed the presence of genes encoding ESBL or AmpC. In ESBL-positive strains, the sensitivity of the ESBL Etest (AB Biodisk) and a modified double-disk synergy test (DDST) were evaluated. AmpC strains were tested by a modified AmpC disk method using 3-aminophenylboronic acid. For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used. RESULTS: The sensitivity of the ESBL Etest was 95%; the modified DDST yielded 100% sensitivity for ESBL producers and the AmpC test correctly detected 95% of AmpC-positive strains. The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively. CONCLUSIONS: The detection of ESBL and AmpC beta lactamases should be based on specific phenotypic methods such as the modified DDST, ESBL Etest, AmpC disk test and the modified microdilution method.

Carbon metabolism of enterobacterial human pathogens growing in epithelial colorectal adenocarcinoma (Caco-2) cells.

Analysis of the genome sequences of the major human bacterial pathogens has provided a large amount of information concerning their metabolic potential. However, our knowledge of the actual metabolic pathways and metabolite fluxes occurring in these pathogens under infection conditions is still limited. In this study, we analysed the intracellular carbon metabolism of enteroinvasive Escherichia coli (EIEC HN280 and EIEC 4608-58) and Salmonella enterica Serovar Typhimurium (Stm 14028) replicating in epithelial colorectal adenocarcinoma cells (Caco-2). To this aim, we supplied [U-(13)C(6)]glucose to Caco-2 cells infected with the bacterial strains or mutants thereof impaired in the uptake of glucose, mannose and/or glucose 6-phosphate. The (13)C-isotopologue patterns of protein-derived amino acids from the bacteria and the host cells were then determined by mass spectrometry. The data showed that EIEC HN280 growing in the cytosol of the host cells, as well as Stm 14028 replicating in the Salmonella-containing vacuole (SCV) utilised glucose, but not glucose 6-phosphate, other phosphorylated carbohydrates, gluconate or fatty acids as major carbon substrates. EIEC 4608-58 used C(3)-compound(s) in addition to glucose as carbon source. The labelling patterns reflected strain-dependent carbon flux via glycolysis and/or the Entner-Doudoroff pathway, the pentose phosphate pathway, the TCA cycle and anapleurotic reactions between PEP and oxaloacetate. Mutants of all three strains impaired in the uptake of glucose switched to C(3)-substrate(s) accompanied by an increased uptake of amino acids (and possibly also other anabolic monomers) from the host cell. Surprisingly, the metabolism of the host cells, as judged by the efficiency of (13)C-incorporation into host cell amino acids, was not significantly affected by the infection with either of these intracellular pathogens.

Weibull analyses of bacterial interaction forces measured using AFM.

Statistically significant conclusions from interaction forces obtained by AFM are difficult to draw because of large data spreads. Weibull analysis, common in macroscopic bond-strength analyses, takes advantage of this spread to derive a Weibull distribution, yielding the probability of occurrence of a force value and the dependability of the data set. Here we propose Weibull distribution as a new way to present nanoscopic bacterial interaction forces obtained using AFM.

Structures of two novel, serologically nonrelated core oligosaccharides of Yokenella regensburgei lipopolysaccharides differing only by a single hexose substitution.

Immunochemical analysis of the Yokenella regensburgei lipopolysaccharides (LPS) indicated the presence of the core oligosaccharide-related immunotypes among the investigated strains. The structure of the core oligosaccharide segment of the Y. regensburgei LPS has been investigated using chemical methods, mass spectrometry, and (1)H, (13)C NMR spectroscopy. It was concluded that the core oligosaccharides of the strains PCM 2476 and PCM 2477 are composed of an undecasaccharide. The combined data revealed two immunotypes of the core oligosaccharide recognized by antibodies against the whole bacterial cells. The structural differences between the core oligosaccharides are limited to the outermost terminal hexopyranose residue. In the core oligosaccharide of the strain PCM 2476, it was identified as alpha-d-Glcp and in that of the strain PCM 2477 as alpha-d-Galp. This subtle difference between the glycoforms of the LPS core appeared to be essential for formation of the epitopes recognized by the specific antibodies directed against the Y. regensburgei whole bacterial cells. The oligosaccharides are not substituted by phosphate groups. Instead, the carboxyl groups of Kdo and galacturonic acid residues present in the core provide the negative charges. The undecasaccharides represent a novel core type of bacterial LPS, which is characteristic for Y. regensburgei.

Associations among milk quality indicators in raw bulk milk.

The objective of this study was to determine characteristics and associations among bulk milk quality indicators from a cohort of dairies that used modern milk harvest, storage, and shipment systems and participated in an intensive program of milk quality monitoring. Bulk milk somatic cell count (SCC), total bacteria count (TBC), coliform count (CC), and laboratory pasteurization count (LPC) were monitored between July 2006 and July 2007. Bulk milk samples were collected 3 times daily (n = 3 farms), twice daily (n = 6 farms), once daily (n = 4 farms), or once every other day (n = 3 farms). Most farms (n = 11) had direct loading of milk into tankers on trucks, but 5 farms had stationary bulk tanks. The average herd size was 924 cows (range = 200 to 2,700), and daily milk produced per herd was 35,220 kg (range = 7,500 to 105,000 kg). Thresholds for increased bacterial counts were defined according to the 75th percentile and were >8,000 cfu/mL for TBC, >160 cfu/mL for CC, and >or=310 cfu/mL for LPC. Means values were 12,500 (n = 7,241 measurements), 242 (n = 7,275 measurements), and 226 cfu/mL (n = 7,220 measurements) for TBC, CC, and LPC, respectively. Increased TBC was 6.3 times more likely for bulk milk loads with increased CC compared with loads containing fewer coliforms. Increased TBC was 1.3 times more likely for bulk milk with increased LPC. The odds of increased TBC increased by 2.4% for every 10,000-cells/mL increase in SCC in the same milk load. The odds of increased CC increased by 4.3% for every 10,000-cells/mL increase in SCC. The odds of increased CC increased by 1% for every 0.1 degrees C increase in the milk temperature upon arrival at the dairy plant (or at pickup for farms with bulk tank). Laboratory pasteurization count was poorly associated with other milk quality indicators. Seasonal effects on bacterial counts and milk temperature varied substantially among farms. Results of this study can be used to aid the interpretation and analysis of indicators of milk quality intensively produced by dairy processors' laboratories.

Detección de betalactamasas de espectro extendido en cepas de la familia enterobacteriaceae / Extended spectrum betalactamase detection in enterobacteriaceae family strains

La alta incidencia de las enfermedades infecciosas y el surgimiento de enterobacterias resistentes a los antibióticos representan un gran problema actualmente, siendo las cepas productoras de Betalactamasas de Espectro Extendido (BLEE) un ejemplo de este fenómeno. A fin de determinar la producción de BLEE en cepas pertenecientes a la familia Enterobacteriaceae aisladas en el Centro de Referencia Bacteriológica del Servicio Autónomo del Hospital Universitario de Maracaibo, durante el periodo enero 2006-diciembre 2007, se analizaron 3883 enterobacterias distribuidas en 14 especies diferentes. Para la detección de BLEE se utilizó como método preliminar el de Kirby-Baüer, siguiendo los lineamientos del CLSI; adicionalmente se utilizaron pruebas confirmatorias como sinergia del doble disco, el método del disco combinado y el método de E-Test ESBL. Del total de enterobacterias estudiadas 951 (24,49 por ciento) fueron productoras de BLEE. K. oxytoca (43,33 por ciento), K. pneumoniae (40,10 por ciento), y Enterobacter cloacae (31,54 por ciento), fueron los microorganismos con mayor producción de BLEE. Al correlacionar la producción de BLEE con el servicio de atención del paciente, se encontró asociación estadísticamente significativa (p<0,05) entre la producción de BLEE y las UCI. Estos resultados reflejan el uso excesivo de antibióticos, lo que trae como consecuencia la aparición y diseminación de la resistencia

The high incidence of infectious diseases and the rise of antibiotic-resistant enterobacteria represent a great medical problem today, and the Extended Spectrum Betalactamase (ESBL)-producing strains are an example of this phenomenon. In order to determine the production of ESBL in strains pertaining to the Enterobacteria family, isolated in the Bacteriological Reference Center at Maracaibo’s University Hospital from January 2006-December 2007, 3883 strains of enterobacteria were analyzed, distributed among 14 different species. To detect ESBL, the Kirby-Baüer test was used as a preliminary method, following the CLSI guidelines; additionally, confirmatory tests such as double disc synergy, the combined disc and E-test ESBL methods were used. Of all the enterobacteria studied, 951 (24.49 percent) were ESBL producers. K. oxytoca (43.33 percent), K. pneumoniae (40.10 percent), and Enterobacter cloacae (31.54 percent) were the microorganisms with greater ESBL production. When correlating ESBL production with the patient services, a statistically significant association (p0.05) between ESBL production and the ICU was detected. These results reflect that excessive antibiotic use produces the appearance and dissemination of resistance

Long-term impacts of pasture irrigation with treated sewage effluent on shallow groundwater quality.

The study investigated the effects of 26 years of effluent irrigation on chemical and bacteriological quality of shallow (<3.0 m) groundwater. Annual loading rates for N and P exceeded pasture requirements, while trace metals were either lower or higher than guideline limits. Effluent irrigation removed TN (44-71%), TP (80%), Cr (96%) and coliform bacteria (87-99.9%) while Zn, Cu and Cd removal was negligible probably due to their enhanced mobility. Analysis of groundwater samples from effluent-irrigated and non-irrigated control sites showed that effluent irrigation increased the levels of all measured parameters compared to the control. Average groundwater quality parameters from effluent-irrigated sites compared to the control were: pH (6.1 vs. 5.7), EC (0.71 vs. 0.53 dS m(-1)), concentrations (mg L(-1)) for TP (2.3 vs. 0.3), DP (1.0 vs. 0.1), TN (15.1 vs. 2.5), NH(4)-N (2.6 vs. 0.5), NO(3)-N (4.1 vs. 1.3), Zn (0.4 vs. 0.05), Cu (0.13 vs. 0.02), Cd (0.05 vs. 0.01) and Cr (0.06 vs. 0.03). Across effluent-irrigated sites, FC and TC were 25 and 288 cfu/100 ml, respectively, versus nil for the control. Overall, effluent irrigation led to groundwater contamination by N, P, trace metals and coliform bacteria, which could threaten the long-term sustainability of the practice.

Evolution of antimicrobial susceptibility patterns of aerobic and facultative gram-negative bacilli causing intra-abdominal infections: results from the SMART studies 2003-2007

Study for Monitoring Antimicrobial Resistance Trends(SMART) is an ongoing global antimicrobial surveillance programfocused on clinical isolates from intra-abdominal infections(IAI). The objective of this subanalysis was to assessthe evolution of the antimicrobial susceptibility patternsamong aerobic and facultative gram-negative bacilli (GNB)recovered over a 5-year period at our institution. We testedthe in vitro activity of the antimicrobials, commonly used totreat IAI, against consecutive unique isolates from IAI usingmicrodilution techniques according to the CLSI guidelinesfor MIC testing. All isolates were screened phenotypically forextended-spectrum beta-lactamase (ESBL) production. Isolatesrecovered within 48 h of hospitalization were consideredcommunity-acquired (CA). Over the study period a total of572 aerobic and facultative gram-negative bacilli were recoveredfrom 510 patients, of which 258 (45%) were CA. Enterobacteriaceaecomposed 91% of the total isolates. Escherichiacoli was the most common isolated species (52%).Susceptibility rates of Enterobacteriaceae ranged from96.5 %-100 % to ertapenem, 96.5 %-100 % to imipenem,87.7%-94.3% to piperacillin-tazobactam, 85.1%-94.3% tocefotaxime, 89.5%-100% to cefepime, 76.3%-84.8% to ciprofloxacin,and 93.8%-100% to amikacin. ESBL were detectedin 6.3% of E. coli, 5.7% of Klebsiella spp. and 2.7% ofEnterobacter spp. ESBL producers generally had a more antibiotic-resistant profile than non-ESBL producers and 16% ofthem were CA. Susceptibility rates to ertapenem, imipenem,piperacillin-tazobactam, ceftazidime, cefepime, ciprofloxacinand amikacin were, respectively, for P. aeruginosa:28.2 %, 58.9%, 82%, 84.6 %, 76.9 %, 71.8% and 82%; forAcinetobacter baumannii: 33.3 %, 100 %, 66.6 %, 66.6 %,66.6%, 66.6% y 66.6%, and for Stenotrophomonas maltophilia:0%, 0%, 0%, 28.6%, 0%, 42.9% and 14.3% (AU)

El Study for Monitoring Antimicrobial ResistanceTrends (SMART) es un programa mundial de vigilancia deresistencia a antimicrobianos de microorganismos aisladosde infecciones intraabdominales. El objetivo de estesubanálisis fue estudiar la evolución de los patrones desensibilidad a antimicrobianos de bacilos gramnegativosaerobios y facultativos aislados durante un períodode 5 años en nuestra institución. Se determinaron las concentracionesmínimas inhibitorias (CMI) de los antimicrobianosmás comúnmente usados para tratar infecciones intraabdominalespor el método de microdilución en caldosiguiendo las recomendaciones del CLSI frente a aisladosconsecutivos procedentes de pacientes con estas infecciones.En todos los aislados se confirmó fenotípicamente laproducción de betalactamasas de espectro extendido(BLEE). Se consideraron de adquisición comunitaria aquellosmicroorganismos aislados durante un máximo de 48 h dehospitalización. Durante el período de estudio se recogieronun total de 572 bacilos gram-negativos aerobios y facultativoscorrespondientes a 510 pacientes, de los cuales258 (45%) fueron de adquisición comunitaria. El 91% de los aislados fueron enterobacterias y Escherichia coli fue laespecie más frecuentemente aislada (52%). Los porcentajesde sensibilidad de las enterobacterias a lo largo de los5 años oscilaron entre el 96,5-100 % para ertapenem, el96,5-100% para imipenem, el 87,7-94,3% para piperacilina-tazobactam, el 85,1-94,3% para cefotaxima, el 89,5-100% para cefepima, el 76,3-84,8% para ciprofloxacinoy el 93,8-100% para amikacina. Se detectaron BLEE en el6,3% de los aislados de E. coli, el 5,7% de Klebsiella spp.y 2,7% de Enterobacter spp. Los aislados productores deBLEE presentaron generalmente mayor multirresistenciaa otros antibióticos que los no productores de BLEE y el16% de ellos fueron de adquisición comunitaria (AU)

Evaluation of media for simultaneous enumeration of total coliform and Escherichia coli in drinking water supplies by membrane filtration techniques.

This study evaluated three different dehydrated media for simultaneous detection and enumeration of total coliform (TC) and Escherichia coli in drinking water samples with a standard membrane filtration procedure. The experiment indicated that the differential coliform agar (DCA) medium was the most effective among the tested media in enumerating TC and E. coli, without the need for extensive accompanying confirmation tests. The results for DCA medium were highly reproducible for both TC and E. coli with standard deviation of 6.0 and 6.1, respectively. A high agreement (82%) was found between DCA and m-Endo media on 152 drinking water samples in terms of TC positive. The DCA medium also reduced concealment of background bacteria.

Pile composting of two-phase centrifuged olive husk residues: technical solutions and quality of cured compost.

The present work proposed an economically sustainable solution for composting olive humid husks (OHH) and leaves (OL) at a small/medium sized olive oil mill. We planned and set up a composting plant, the prototype taking the form of a simplified low-cost turning machine, and evaluated the use of an inoculum of one year-old composted humid husks (CHH) and sheep manure (SM) to facilitate the starting phase of the process. Trials were carried out using four piles under different experimental conditions (turnover, static, and type of inoculum). The best results were achieved with turnover and an inoculum that induced fast start-up and a correct evolution of the composting process. The final product was a hygienically clean, cured compost.