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In this study, the photoinactivation of Legionella by visible light is investigated. The success of this approach would offer new prospects for technical water disinfection and maybe even for therapeutic measures in cases of Legionella infections. Therefore, Legionella rubrilucens was dispensed on buffered charcoal yeast extract medium agar plates and illuminated with different doses of violet light generated by 405 nm light-emitting diodes (LEDs). A strong photoinactivation effect was observed. A dose of 125 J/ cm2 reduced the bacterial concentration by more than 5 orders of magnitude compared to Legionella on unirradiated agar plates. The necessary dose for a one log-level reduction was about 24 J/cm2. These results were obtained for extracellular L. rubrilucens, but other Legionella species may exhibit a similar behavior.

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Bacterial antimicrobial resistance mediated by the production of extended-spectrum β-lactamases (ESBLs) is considered a major threat for treatment of Salmonella and Shigella infections. This study aimed to investigate antibiotic resistance patterns of Salmonella and Shigella spp. and presence of CTX-M from three teaching hospitals in Iran. In the present study, 58 clinical Shigella and 91 Salmonella isolates were recovered between 2009 and 2013 from 3 teaching hospitals in Iran. After culture and antimicrobial susceptibility testing, ESBL-positive isolates were subjected to further investigations. These included polymerase chain reaction (PCR) amplification and DNA sequencing of bla CTX-M-15 encoding plasmid. In both genera, high sensitivity to gentamicin and amikacin, but high resistance to ampicillin, tetracycline, and trimethoprim—sulfamethoxazole, was found. Molecular investigation showed that 31.8% isolates of Salmonella spp. and 34.48% isolates of Shigella spp. were CTX-M positive and all of them were also positive for ISEcpI. Protein translation, comparing with reference sequences, showed that all CTX-M isolates belong to CTX-M-15. The present study suggests that the resistance of ESBLs-producing Salmonella and Shigella spp. in Iran hospitals is very serious. Therefore, strategies to minimize the spread of ESBL-producing isolates should be implemented.

Open access

Host immune responses are crucial for combating enteropathogenic infections including Campylobacter jejuni. Within 1 week following peroral C. jejuni infection, secondary abiotic IL-10−/− mice develop severe immunopathological sequelae affecting the colon (ulcerative enterocolitis). In the present study, we addressed whether pathogen-induced pro-inflammatory immune responses could also be observed in the small intestines dependent on the innate receptor nucleotide-oligomerization-domain-protein 2 (Nod2). Within 7 days following peroral infection, C. jejuni stably colonized the gastrointestinal tract of both IL-10−/− mice lacking Nod2 (Nod2−/− IL-10−/−) and IL-10−/− controls displaying bloody diarrhea with similar frequencies. Numbers of apoptotic and regenerating epithelial cells increased in the small intestines of C. jejuni-infected mice of either genotype that were accompanied by elevated ileal T and B lymphocyte counts. Notably, ileal T cell numbers were higher in C. jejuni-infected Nod2−/− IL-10−/− as compared to IL-10−/− counterparts. Furthermore, multifold increased concentrations of pro-inflammatory cytokines including IFN-γ, TNF, and MCP-1 could be measured in small intestinal ex vivo biopsies derived from C. jejuni-infected mice of either genotype. In conclusion, C. jejuni-induced pro-inflammatory immune responses affected the small intestines of both Nod2−/− IL-10−/− and IL-10−/− mice, whereas ileal T lymphocyte numbers were even higher in the former.

Open access

The metacommunity perspective has substantially advanced our understanding of how local (within community) and dispersal (between community) processes influence the assembly of communities. The increased recognition of dispersal processes makes it necessary to re-evaluate former views on community organization in different ecological systems and for specific organisms. Stream systems have long been considered from a linear perspective, in which local community organization was examined along the longitudinal profile, from source to mouth. However, the hierarchically branching (i.e. dendritic) structure of stream networks also significantly affects both local and regional scale community organization, which has just only recently been fully recognized by ecologists. In this review, I examine how the shift from a strictly linear to a dendritic network perspective influenced the thinking about the organization of fish metacommunities in stream networks. I argue that while longitudinal patterns in the structure of fish communities are relatively well known, knowledge is still limited about how the structure of the stream network ultimately affects the spatial and temporal dynamics of metacommunities. I suggest that scaling metapopulation models up to the metacommunity level can be useful to further our understanding of the spatial structure of metacommunities. However, this requires the delineation of local communities and the quantification of the contribution of dispersal to local community dynamics. Exploring patterns in diversity, spatial distribution and temporal dynamics of metacommunities is not easily feasible in continuous stream habitats, where some parts of the habitat network are exceptionally hard to sample representatively. Combination of detailed field studies with modelling of dispersal is necessary for a better understanding of metacommunity dynamics in stream networks. Since most metacommunity level processes are likely to happen at the stream network level, further research on the effects of stream network structure is needed. Overall, separation of the effect of dispersal processes from local scale community dynamics may yield a more mechanistic understanding of the assembly of fish communities in stream networks, which may also enhance the effectiveness of restoration efforts.

Open access

Phenotypic and genotypic evaluation of wheat genetic resources and development of segregating populations are pre-requisites for identifying rust resistance genes. The objectives of this study were to assess adult plant resistance (APR) of selected wheat genotypes to leaf rust and stem rust and to develop segregating populations for resistance breeding. Eight selected Kenyan cultivars with known resistance to stem rust, together with local checks were evaluated for leaf rust and stem rust resistance at seedling stage and also across several environments. Selected diagnostic markers were used to determine the presence of known genes. All eight cultivars were crossed with local checks using a bi-parental mating design. Seedling tests revealed that parents exhibited differential infection types against wheat rust races. Cultivars Paka and Popo consistently showed resistant infection types at seedling stage, while Gem, Romany, Pasa, Fahari, Kudu, Ngiri and Kariega varied for resistant and susceptible infection types depending on the pathogen race used. The control cultivars Morocco and McNair consistently showed susceptible infection types as expected. In the field, all cultivars except for Morocco showed moderate to high levels of resistance, indicating the presence of effective resistance genes. Using diagnostic markers, presence of Lr34 was confirmed in Gem, Fahari, Kudu, Ngiri and Kariega, while Sr2 was present in Gem, Romany, Paka and Kudu. Seedling resistance gene, Sr35, was only detected in cultivar Popo. Overall, the study developed 909 F6:8 recombinant inbred lines (RILs) as part of the nested mating design and are useful genetic resources for further studies and for mapping wheat rust resistance genes.

Open access
European Journal of Microbiology and Immunology
Authors: Comoé Koffi Donatien Benie, Adjéhi Dadié, Nathalie Guessennd, Nadège Ahou N’gbesso-Kouadio, N’zebo Désiré Kouame, David Coulibaly N’golo, Solange Aka, Etienne Dako, Koffi Marcellin Dje, and Mireille Dosso

Pseudomonas aeruginosa owns a variability of virulence factors. These factors can increase bacterial pathogenicity and infection severity. Despite the importance of knowledge about them, these factors are not more characterized at level of strains derived from local food products. This study aimed to characterize the virulence potential of P. aeruginosa isolated from various animal products. Several structural and virulence genes of P. aeruginosa including lasB, exoS, algD, plcH, pilB, exoU, and nan1 were detected by polymerase chain reaction (PCR) on 204 strains of P. aeruginosa. They were isolated from bovine meat (122), fresh fish (49), and smoked fish (33). The 16S rRNA gene was detected on 91.1% of the presumptive strains as Pseudomonas. The rpoB gene showed that 99.5% of the strains were P. aeruginosa. The lasB gene (89.2%) was the most frequently detected (p < 0.05). In decreasing importance order, exoS (86.8%), algD (72.1%), plcH (72.1%), pilB (40.2%), and exoU (2.5%) were detected. The lasB gene was detected in all strains of P. aeruginosa serogroups O11 and O16. The prevalence of algD, exoS, and exoU genes in these strains varied from 51.2% to 87.4%. The simultaneous determination of serogroups and virulence factors is of interest for the efficacy of surveillance of infections associated with P. aeruginosa.

Open access

Reliable identification of pathogenic Burkholderia spp. like Burkholderia mallei and Burkholderia pseudomallei in clinical samples is desirable. Three different selective media were assessed for reliability and selectivity with various Burkholderia spp. and nontarget organisms.

Mast Burkholderia cepacia agar, Ashdown + gentamicin agar, and B. pseudomallei selective agar were compared. A panel of 116 reference strains and well-characterized clinical isolates, comprising 30 B. pseudomallei, 20 B. mallei, 18 other Burkholderia spp., and 48 nontarget organisms, was used for this assessment.

While all B. pseudomallei strains grew on all three tested selective agars, the other Burkholderia spp. showed a diverse growth pattern. Nontarget organisms, i.e., nonfermentative rod-shaped bacteria, other species, and yeasts, grew on all selective agars. Colony morphology did not allow unambiguous discrimination.

While the assessed selective media reliably allowed the growth of a wide range of B. pseudomallei strains, growth of other Burkholderia spp. is only partially ensured. Growth of various nontarget organisms has to be considered. Therefore, the assessed media can only be used in combination with other confirmative tests in the diagnostic procedure for the screening for melioidosis or glanders.

Open access

Secondary abiotic mice generated by broad-spectrum antibiotic treatment provide a valuable tool for association studies with microbiota derived from different vertebrate hosts. We here generated human microbiota-associated (hma) mice by human fecal microbiota transplantation of secondary abiotic mice and performed a comprehensive survey of the intestinal microbiota dynamics in offspring of hma mice over 18 weeks following weaning as compared to their mothers applying both cultural and molecular methods. Mice were maintained under standard hygienic conditions with open cages, handled under aseptic conditions, and fed autoclaved chow and water. Within 1 week post weaning, fecal loads of commensal enterobacteria and enterococci had decreased, whereas obligate anaerobic bacteria such as Bacteroides/Prevotella species and clostridia were stably colonizing the intestines of hma offspring at high loads. Lactobacilli numbers were successively increasing until 18 weeks post weaning in both hma offspring and mothers, whereas by then, bifidobacteria were virtually undetectable in the former only. Interestingly, fecal lactobacilli and bifidobacteria were higher in mothers as compared to their offspring at 5 and 18 weeks post weaning. We conclude that the intestinal microbiota composition changes in offspring of hma mice, but also their mothers over time particularly affecting aerobic and microaerobic species.

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This study was carried out in order to investigating the effect of travelling on the transmission of tuberculosis from high- to low-burden TB countries. Mycobacteria samples isolated from patients of distinct and relatively co-related countries (Azerbaijan Republic and Tabriz [located in the northwest of Iran]) were analyzed through 15 loci MIRU-VNTR typing method. PCR was done using special primers for each of the loci; then the number of allele repeats for all loci were determined by the size of their fragments. Finally, the created numeric patterns for each isolate were analyzed and clustered, using MIRU-VNTRplus.org website. All 119 isolates dispersing at 106 distinct patterns were composed of 10 clusters with 23 members and 96 unique patterns. Nine and five loci had high and moderate discriminatory power, respectively, but only one of them was poor in clustering. The study showed that 89.08% of TB cases involved resulted from the reactivation pattern and 10.92% were related to ongoing transmission. Although Azerbaijan Republic is a higher-burden TB region than Tabriz and Azerbaijan people make frequent tours to Tabriz to receive low or free medical services, the findings showed no TB transmission from the regions at least during the year of the study.

Open access

Melanin-concentrating hormone (MCH), the neuropeptide produced mainly in the hypothalamus, plays an operative role in regulating food intake and the sleep/wake cycle. Considering that these physiological functions pursue diurnal variations, we checked whether the total hypothalamic MCH level depends on the time of the day. The aggregated MCH peptide content of the whole MCH neuron population was significantly higher at the end of the sleeping period (lights on), than at the end of the active period (lights off). This result, together with earlier observations, indicates that in contrast to the MCH gene expression, the level of MCH peptide is object of circadian variation in the hypothalamus.

Open access