Significance Effective treatment of skin-based bacterial biofilms has been identified as a serious and unmet medical need. Biofilm-protected bacteria account for ∼80% of bacterial infections in ...humans and are 50–1,000 times more resistant to antibiotics than their planktonic counterparts. Biofilms in skin are further protected by the outermost layer of skin, the stratum corneum, which serves as a natural barrier to most therapeutics. Here, we present compelling evidence for exploiting ionic liquids (ILs) as an arsenal of materials both in a concerted effort to combat antibiotic-resistant bacterial biofilms in skin as well as for topical transdermal drug delivery. Our comprehensive strategy resulted in the identification of ILs that are effective at disrupting biofilms, neutralizing pathogens, and enhancing delivery of antibiotic into skin. Moreover, ILs did not show skin irritation that is typically associated with topical formulations.
This study compared the populations of antimicrobial-resistant bacteria and the repertoire of antimicrobial resistance genes in four environments: effluent of three municipal waste water treatment ...facilities, three cattle feedlot runoff catchment ponds, three swine waste lagoons, and two "low impact" environments (a municipal lake and a relict prairie). Multiple liquid and solid samples were collected from each environment. The prevalences and concentrations of antimicrobial-resistant (AMR) Gram-negative (Escherichia coli and Salmonella enterica) and Salmonella prevalences of 83 antimicrobial resistance genes in metagenomic DNA isolated from samples pooled (n= 44) by collection date, location, and sample type were determined. The prevalences and concentrations of AMR E. coli and S. Salmonella were similar among the livestock and municipal sample sources. The levels of erythromycin-resistant enterococci were significantly higher in cattle runoff and swine waste lagoon liquid samples compared to municipal samples, but not significantly different in solid samples. Similarly, trimethoprim/sulfamethoxazole-resistant E. coli concentrations were significantly higher in swine liquid than in municipal liquid samples, but there was no difference in solid samples. Individual antimicrobial resistance genes were significantly clustered within livestock, low impact, and municipal samples, with municipal samples harboring the highest number of antimicrobial resistance genes. The numbers of class A beta-lactamase, class C beta-lactamase, and fluoroquinolone resistance genes detected were significantly higher (P < 0.05) in municipal samples than in cattle runoff or swine lagoon samples. In conclusion, we report that AMR is a very widespread phenomenon and that similar prevalences and concentrations of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes exist in cattle, human, and swine waste streams, but a higher diversity of antimicrobial resistance genes are present in human waste streams.
This study was designed to develop a multiplex PCR method with five specific primer pairs for the detection of Salmonella spp., Salmonella subspecies I, Salmonella enterica serovars Typhimurium, ...Typhi and Enteritidis. A multiplex PCR was constructed with five primer pairs for the detection of Salmonella and pathogenic Salmonella serovars, including a specific primer pair for Salmonella Typhi, based on the sequence comparison between genomic DNA sequences of 12 Salmonella strains. Each primer pair was specifically targeted to Salmonella spp., Salmonella subspecies I, Salmonella Typhimurium, Typhi and Enteritidis. This multiplex PCR was evaluated with various DNAs of Salmonella serovars that yielded high specificity for amplifying the expected PCR products of Salmonella serovars. Using this primer pair, a set of multiplex PCR was performed for the rapid identification of salmonellae and major pathogenic Salmonella serovars. Although this multiplex PCR method will need to be evaluated for a wide range of Salmonella serovars among multilaboratories, it should be useful for identifying clinically significant strains of Salmonella serovars rapidly and accurately without the need for serological testing.
SP6 is a salmonella phage closely related to coliphage K1-5. K1-5 is notable in that it encodes two polysaccharide-degrading tailspike proteins, an endosialidase that allows it to infect E. coli K1, ...and a lyase that enables it to infect K5 strains. SP6 is similar to K1-5 except that it encodes a P22-like endorhamnosidase tailspike, gp46, allowing it to infect group B Salmonella. We show here that SP6 can also infect Salmonella serogroups C
and C
and that a mutation in a putative second tailspike, gp47, eliminates this specificity. Gene 47 was fused to the coding region of the N-terminal portion of the Pseudomonas aeruginosa R2 pyocin tail fiber and expressed in trans such that the fusion protein becomes incorporated into pyocin particles. These pyocins, termed AvR2-SP47, killed serogroups C
and C
Salmonella. We conclude that SP6 encodes two tail proteins providing it a broad host range among Salmonella enterica.
Phase variation of the Salmonella enterica opvAB operon generates a bacterial lineage with standard lipopolysaccharide structure (OpvAB super(OFF)) and a lineage with shorter O-antigen chains (OpvAB ...super(ON)). Regulation of OpvAB lineage formation is transcriptional, and is controlled by the LysR-type factor OxyR and by DNA adenine methylation. The opvAB regulatory region contains four sites for OxyR binding (OBS sub(A-D)), and four methylatable GATC motifs (GATC sub(1-4)). OpvAB super(OFF) and OpvAB super(ON) cell lineages display opposite DNA methylation patterns in the opvAB regulatory region: (i) in the OpvAB super(OFF) state, GATC sub(1) and GATC sub(3) are non-methylated, whereas GATC sub(2) and GATC sub(4) are methylated; (ii) in the OpvAB super(ON) state, GATC sub(2) and GATC sub(4) are non-methylated, whereas GATC sub(1) and GATC sub(3) are methylated. We provide evidence that such DNA methylation patterns are generated by OxyR binding. The higher stability of the OpvAB super(OFF) lineage may be caused by binding of OxyR to sites that are identical to the consensus (OBS sub(A) and OBS sub(c)), while the sites bound by OxyR in OpvAB super(ON) cells (OBS sub(B) and OBS sub(D)) are not. In support of this view, amelioration of either OBS sub(B) or OBS sub(D) locks the system in the ON state. We also show that the GATC-binding protein SeqA and the nucleoid protein HU are ancillary factors in opvAB control.
Summary
In livestock production, antibiotics are used to promote animal growth, control infections and thereby increase profitability. This practice has led to the emergence of multiresistant ...bacteria such as Salmonella, of which some serovars are disseminated in the environment. The objective of this study is to evaluate microcin J25 as an inhibitor of Salmonella enterica serovars of various origins including human, livestock and food. Among the 116 isolates tested, 37 (31.8%) were found resistant to at least one antibiotic, and 28 were multiresistant with 19 expressing the penta‐resistant phenotype ACSSuT. Microcin J25 inhibited all isolates, with minimal inhibitory concentration values ranging from 0.06 μg/ml (28.4 nM) to 400 μg/ml (189 μM). Interestingly, no cross‐resistance was found between microcin J25 and antibiotics. Multiple sequence alignments of genes encoding for the different proteins involved in the recognition and transport of microcin J25 showed that only ferric‐hydroxamate uptake is an essential determinant for susceptibility of S. enterica to microcin J25. Examination of Salmonella strains exposed to microcin J25 by transmission electronic microscopy showed for the first‐time involvement of a pore formation mechanism. Microcin J25 was a strong inhibitor of several multiresistant isolates of Salmonella and may have a great potential as an alternative to antibiotics.
Salmonella enterica serovars cause severe disease in humans, such as gastroenteritis and typhoid fever. The bacteria are able to invade and replicate within host cells, including epithelial cells and ...macrophages. Pathogenesis of Salmonella is facilitated by a type III secretion system (T3SS) encoded by genes of Salmonella pathogenicity island 2 (SPI-2). Intracellular replication occurs in a specialized membrane compartment, the Salmonella-containing vacuole (SCV), and depends on translocation of approximately 30 effector proteins via the SPI-2 T3SS into the host endomembrane system and cytoplasm. In this review we discuss the many different functions of these effectors, which range from maintaining the integrity of the SCV and its juxtanuclear location, to interference with the host cytoskeleton and immune signalling.
192 Food samples (commonly consumed 8 food types), 355 animal samples (animal feces of bovine, ovine, goat and chicken) and 50 samples from clinical human cases in Sanliurfa city, Turkey in a year ...were collected to determine the Salmonella enterica subsp. enterica mosaic in Turkey. 161 Salmonella isolates represented 17 serotypes, 20 sequence types (STs) and 44 PFGE patterns (PTs). 3 serotypes, S. Enteritidis, S. Typhimurium and S. Kentucky, were recovered from three different hosts. The highest discriminatory power was obtained by PFGE (SID=0.945), followed by MLST (SID=0.902) and serotyping (SID=0.885) for all isolates. The prevalence of antimicrobial resistance genes (aadA1, aadA2, strA, strB, aphA1-Iab, blaTEM-1, blaPSE-1, tetA) was highly correlated with phenotypic profiles of aminoglycoside, ß-lactam and tetracycline groups (kappa >0.85). From our knowledge, this is the first study reporting spatial and temporal distribution of Salmonella species through phenotypic and genetic approaches over farm to fork chain in Turkey. Thus, our data provided further information for evolution, ecology and transmission of Salmonella in Turkey.
•Salmonella serotype diversity has changed in food, animal and human isolates.•PFGE has given more diverged subtypes compared to MLST and serotyping.•Multidrug resistance is mostly observed in serotypes: Infantis, Hadar, Typhimurium.•Distribution of antimicrobial resistance genes varied within source, and serotype.
PDF
