Opportunistic Pathogenic Bacteria Research Articles

Influences of the diurnal cycle on gut microbiota in the Chinese swamp shrimp (Neocaridina denticulata)

ABSTRACT The circadian rhythm is an essential environmental factor affecting several physiological activities in organisms, including crustaceans. However, daily variations in the gut bacterial community composition of crustaceans remain poorly understood. This study aimed to elucidate variations in the gut bacterial community composition of the Chinese swamp shrimp Neocaridina denticulata with the diurnal cycle. The gut samples of 600 shrimps were collected at four time points (6:00, 12:00, 18:00, and 24:00) within a 24 h period and 16S rRNA high-throughput gene sequencing was applied. The alpha-diversity and richness of the gut bacterial community were highest in the 24:00 group. Food digestion- and absorption-related pathways were highly enriched, indicating that metabolic process pathways are influenced by the daily cycle. Opportunistic pathogenic bacteria, including Flavobacterium, Acinetobacter, and Pseudomonas, were well-represented in the 18:00 and 24:00 groups, suggesting that the daily cycle shapes pathogenic bacterial community composition in the shrimp intestine. Our findings provide new insights into the role of diurnal cycles on gut bacteria in crustaceans and may aid in improving N. denticulata aquaculture.

Changes in Amino Acid Metabolism of Staphylococcus aureus following Growth to the Stationary Phase under Adjusted Growth Conditions.

The sharp increase in infections due to Staphylococcus aureus is associated with its ability to adapt to changes in its habitat. This study aimed to investigate the differences in the cytoplasmic amino acid profiles of a clinical strain of S. aureus under five combinations of stress-induced conditions representative of a wound site by varying temperature 35–37 °C, adding 0–5% NaCl and adjusting pH 6–8. The results indicated that aspartic acid, lysine, glutamic acid and histidine were the most abundant cytoplasmic amino acids in the control samples grown under optimal growth conditions. However, the magnitudes and levels of these amino acids were altered under the various wound site conditions, which led to differential cytoplasmic amino acid profiles as characterized by multivariate analyses (PLS-DA). The total cytoplasmic amino acid content was significantly reduced in the cells grown with 2.5% NaCl added at pH 7 and 37 °C relative to the control samples and other growth regimes. However, all combinations of enhanced stress conditions showed unique and characteristic changes in the concentration profiles of the cytoplasmic amino acids. These outcomes supported the hypothesis that bacterial cells of S. aureus maintain different metabolic homeostasis under various stress-induced conditions. The potent capability of S. aureus to constantly and rapidly acclimatize to variations within the environment may reflect the crucial feature supporting its virulence as an opportunistic pathogenic bacterium to invade the wound site. Understanding the control systems governing these marked changes in amino acids during the adaptation to the potential wound site conditions of this dangerous bacterium may offer new clinical controls to combat infection.

Flavaspidic acid BB combined with mupirocin improves its anti-bacterial and anti-biofilm activities against Staphylococcus epidermidis

BackgroundThe increase in drug-resistant opportunistic pathogenic bacteria, especially of antibiotic-resistant Staphylococcus epidermidis (S. epidermidis), has led to difficulties in the treatment of skin and soft tissue infections (SSTI). The major reason for bacterial resistance is the formation of bacterial biofilm. Here, we report a promising combination therapy of flavaspidic acid BB (BB) and mupirocin, which can effectively eradicate the biofilm of S. epidermidis and eliminate its drug resistance.ResultThe susceptibility test showed that the combination of BB and mupirocin has good antibacterial and antibiofilm activities, and the fractional inhibitory concentration index (FICI) of BB combined with mupirocin was 0.51 ± 0.00 ~ 0.75 ± 0.05, showing synergistic effect. Moreover, the time-kill curve assay results indicated that the combination of drugs can effectively inhibit the planktonic S. epidermidis. After drugs treatment, the drug-combination showed significantly inhibitory effects on the metabolic activity and total biomass in each stage of biofilm formation. The synergistic effect is likely related to the adhesion between bacteria, which is confirmed by field emission scanning electron microscope. And the expression level of aap, sarA and agrA genes were detected by real-time quantitative PCR (qRT-PCR).ConclusionOur study provides the experimental data for the use of BB for the clinical treatment of skin infections and further demonstrate the potential of BB as a novel biofilm inhibitor.

Antimicrobial Activities against Opportunistic Pathogenic Bacteria Using Green Synthesized Silver Nanoparticles in Plant and Lichen Enzyme-Assisted Extracts.

Enzyme-assisted extraction is a valuable tool for mild and environmentally-friendly extraction conditions to release bioactive compounds and sugars, essential for silver nanoparticle (AgNP) green synthesis as capping and reducing agents. In this research, plant and fungal kingdoms were selected to obtain the enzyme-assisted extracts, using green synthesized AgNPs. For the synthesis, pseudo-cereal Fagopyrum esculentum (F. esculentum) and lichen Certaria islandica (C. islandica) extracts were used as environmentally-friendly agents under heating in an aqueous solution. Raw and enzyme-assisted extracts of AgNPs were characterized by physicochemical, phytochemical, and morphological characteristics through scanning and transmission electron microscopy (SEM and TEM), as well as Fourier transform infrared spectroscopy (FTIR). The synthesized nanoparticles were spherical in shape and well dispersed, with average sizes ranging from 10 to 50 nm. This study determined the total phenolic content (TPC) and in vitro antioxidant activity in both materials by applying standard methods. The results showed that TPC, ABTS•+, FRAP, and DPPH• radical scavenging activities varied greatly in samples. The AgNPs derived from enzymatic hydrolyzed aqueous extracts C. islandica and F. esculentum exhibited higher antibacterial activity against the tested bacterial pathogens than their respective crude extracts. Results indicate that the extracts’ biomolecules covering the AgNPs may enhance the biological activity of silver nanoparticles and enzyme assistance as a sustainable additive to technological processes to achieve higher yields and necessary media components.

In vitro study on the antimicrobial activity of eleven essential oils against oral cavity microbiota

Obtained from aromatic plants, essential oils have been utilised as natural food preservatives. Their ability to inhibit microorganism growth results from their varied chemical compositions. Furthermore, due to their classification as generally recognised as safe (GRAS) and low toxicity levels, there has been an increased study of essential oils’ compositions and antimicrobial properties against pathogens living in the human oral cavity. An initial evaluation was conducted with 11 essential oils to verify their antimicrobial activities in vitro against opportunistic pathogenic bacteria Staphylococcus aureus, Streptococcus sanguinis and Streptococcus mutans, also a model yeast Candida albicans. The antimicrobial activity was evaluated by agar disk diffusion assay, while PT kindly provided chemical composition data. Darjeeling Sembrani Aroma. The result showed that tested essential oils exhibited an inhibition zone range of 8.13 to 40.00 mm for bacteria and 7.63 to 44.04 mm for yeast. Chemical compositions of the oils revealed that the major compounds are monoterpenes, followed by sesquiterpenes and phenylpropanoids.

Gut Microbiota Characteristics Are Associated With Severity of Acute Radiation-Induced Esophagitis.

BackgroundAcute radiation-induced esophagitis (ARIE) is one of the most debilitating complications in patients who receive thoracic radiotherapy, especially those with esophageal cancer (EC). There is little known about the impact of the characteristics of gut microbiota on the initiation and severity of ARIE.Materials and MethodsGut microbiota samples of EC patients undergoing radiotherapy (n = 7) or concurrent chemoradiotherapy (n = 42) were collected at the start, middle, and end of the radiotherapy regimen. Assessment of patient-reported ARIE was also performed. Based on 16S rRNA gene sequencing, changes of the gut microbial community during the treatment regimen and correlations of the gut microbiota characteristics with the severity of ARIE were investigated.ResultsThere were significant associations of several properties of the gut microbiota with the severity of ARIE. The relative abundance of several genera in the phylum Proteobacteria increased significantly as mucositis severity increased. The predominant genera had characteristic changes during the treatment regimen, such as an increase of opportunistic pathogenic bacteria including Streptococcus. Patients with severe ARIE had significantly lower alpha diversity and a higher abundance of Fusobacterium before radiotherapy, but patients with mild ARIE were enriched in Klebsiella, Roseburia, Veillonella, Prevotella_9, Megasphaera, and Ruminococcus_2. A model combining these genera had the best performance in prediction of severe ARIE (area under the curve: 0.907).ConclusionThe characteristics of gut microbiota before radiotherapy were associated with subsequent ARIE severity. Microbiota-based strategies have potential use for the early prediction of subsequent ARIE and for the selection of interventions that may prevent severe ARIE.

Mechanisms of group B Streptococcus-mediated preterm birth: lessons learnt from animal models.

Group B Streptococcus (GBS) is an opportunistic pathogenic bacterium which upon colonization in the female reproductive tract can cause preterm births, fetal injury, and demise. Several determinants for GBS pathogenesis have been explored so far through the studies using animal models ranging from mice to non-human primates. The results from these experimental data have identified outer membrane vesicles, β-hemolysin, hyaluronidase, and Cas9 of GBS as major virulence factors leading to preterm births. Most of these factors drive inflammation through activation of NLRP3 and elevated production of IL1-β. However, the absence of one of the factors from the pathogen reduces but does not completely abolish the pathogenesis of GBS suggesting the involvement of more than one factor in causing preterm birth. This makes further exploration of other virulence factors of GBS pathogenesis important in gaining an insight into the mechanistic basis of GBS-mediated preterm births.Lay summaryGroup B Streptococcus (GBS) is a pathogenic bacteria whose infection in the reproductive tract during pregnancy can cause premature delivery. This bacterial infection is one of the major causes of death of mother and baby during pregnancy, and the bacteria is prevalent in all parts of the world. This makes the research on GBS so important and many of the mechanisms behind GBS infection during pregnancy still remain unexplored. In this review, we have outlined how various animal models contributed in finding the mechanism of GBS pathogenesis. The review also focuses on compiling various virulence factors which makes GBS pathogenic in the vulnerable. Understanding the mechanisms of infection by GBS will be crucial in developing drugs and vaccines to protect against the harmful effects of the bacteria.

Influence of different regimens of volumetric therapy on perioperative intestinal flora in the surgical patients with pancreas tumor, a randomized controlled trial study

BackgroundIt is not clear whether the perioperative intestinal microenvironment of patients undergoing pancreatic tumor surgery is affected by intraoperative fluid therapy.MethodFifty-eight patients who underwent a confined excision of pancreas mass at this center were enrolled. The patients were grouped according to the random number table in these two groups: the liberal fluid infusion (LFI) group and the goal-directed fluid therapy (GDFT) group. Perioperative anesthesia management was carried out by the same team of anesthesiologists according to a preset anesthetic protocol. Fecal samples were collected twice: within 2 days before the surgery and at 6 to 8 days postoperatively. The collected fecal samples were sequenced through microbial diversity high-throughput 16 s-rDNA; and the differential changes of intestinal flora were analyzed.ResultsMain components of flora in the sample were significantly different between LFI and GDFT groups. As shown by the difference in species, in GDFT group, more constituent bacteria participated in the metabolism inside human body and the restoration of coagulation function, including: prevotella, roseburia, lachnospiracea, dialister and clostridium (P < 0.05); in LFI group, more constituent bacteria were opportunistic pathogenic bacteria, including: enterococcus, pseudomonas aeruginosa, and acinetobacter baumannii (P < 0.05).ConclusionFor surgical patients with pancreas tumor, there are significant differences of intestinal flora in diversity between GDFT and LFI. GDFT seems to play a more important role in protection and restoration of intestinal flora.Clinical trial registrationChiCTR2000035187.

Parishin From Gastrodia Elata Ameliorates Aging Phenotype in Mice in a Gut Microbiota-Related Manner

The physiological and pathological processes that accompany aging can seriously affect the quality of life of the elderly population. Therefore, delaying aging and developing antiaging products have become popular areas of inquiry. Gut microbiota plays an important role in age-related phenotypes. The present study aimed to investigate the antiaging effects and underlying mechanism of parishin, a phenolic glucoside isolated from traditional Chinese medicine Gastrodia elata. Samples from adult (12 weeks), low-dose (10 mg/kg/d) or high-dose (20 mg/kg/d) parishin-treated and untreated aged (19 months) mice were collected to determine blood indicators, gut microbiota and metabolome, and cardiopulmonary histopathological features. The results showed that parishin treatment ameliorates aging-induced cardiopulmonary fibrosis and increase in serum p16Ink4a, GDF15, and IL-6 levels. Furthermore, parishin treatment alleviated dysbiosis in gut microbiota, including altered microbial diversity and the aberrant abundance of opportunistic pathogenic bacteria such as Turicibacter and Erysipelatoclostridium. Gene function prediction and gut metabolome analysis results indicated that the parishin treatment-altered gut microbiota played important roles in sugar, lipid, amino acid and nucleic acid metabolism, and improved gut metabolic disorders in aged mice. In conclusion, the present study provides an experimental basis of potential applications of parishin against aging.

Digestive Characteristics of Hericium erinaceus Polysaccharides and Their Positive Effects on Fecal Microbiota of Male and Female Volunteers During in vitro Fermentation.

Hericium erinaceus polysaccharides (HEPs) have attracted widespread attention in regulating gut microbiota (GM). To investigate digestibility and fermentation of HEPs and their effects on GM composition, three polysaccharide fractions, namely, HEP-30, HEP-50, and HEP-70, were fractionally precipitated with 30%, 50%, and 70% ethanol concentrations (v/v) from hot water-soluble extracts of Hericium erinaceus, respectively. Three kinds of prepared HEPs were structurally characterized and simulated gastrointestinal digestion, and their effects on human fecal microbiota fermentations of male and female and short-chain fatty acid (SCFA) production in vitro were clarified. Under digestive conditions simulating saliva, stomach, and small intestine, HEPs were not significantly influenced and safely reached the distal intestine. After 24 h of in vitro fermentation, the content of SCFAs was significantly enhanced (p < 0.05), and the retention rates of total and reducing sugars and pH value were significantly decreased (p < 0.05). Thus, HEPs could be utilized by GM, especially HEP-50, and enhanced the relative abundance of SCFA-producing bacteria, e.g., Bifidobacterium, Faecalibacterium, Blautia, Butyricicoccus, and Lactobacillus. Furthermore, HEPs reduced the relative abundances of opportunistic pathogenic bacteria, e.g., Escherichia-Shigella, Klebsiella, and Enterobacter. This study suggests that gradual ethanol precipitation is available for the preparation of polysaccharides from Hericium erinaceus, and the extracted polysaccharide could be developed as functional foods with great development value.

Microbiota Survey of Sliced Cooked Ham During the Secondary Shelf Life.

Sliced cooked ham packaged in a modified atmosphere is a popular ready-to-eat product, subjected to abundant microbial contamination throughout its shelf life that can lead to deterioration of both sensorial properties and safety. In this study, the microbial load and the chemical–physical features of cooked ham of five producers were monitored for a period of 12 days after the opening of the packages (i.e., the secondary shelf life), during which the products were stored in a domestic refrigerator at 5.2 ± 0.6°C. The sensorial properties presented a perceivable decay after 8 days and became unacceptable after 12 days. High-performance liquid chromatography analysis and solid-phase microextraction coupled with gas chromatography profiling of volatile metabolites indicated that lactic acid, ethanol, acetic acid, acetoin, 3-methyl-1-butanol, and 2-3 butanediol were the main metabolites that characterized the evolution of the analyzed cooked ham. The microbiota was monitored by 16S ribosomal RNA gene profiling and culture-dependent techniques. Already at the opening of packages, all the products presented high microbial load, generally dominated by lactic acid bacteria, with evident differences among the products. The increase of lactic acid bacteria somehow protected samples from abundant contamination by other bacteria, concurring with the evolution of more safe products. This role was exerted by numerous Latilactobacillus, Leuconostoc, and Carnobacterium species, among which the most frequently detected were Latilactobacillus sakei, Latilactobacillus sakei carnosum, Leuconostoc mesenteroides, and Carnobacterium divergens. Some products presented more complex communities that encompassed Proteobacteria such as Moellerella wisconsensis, Proteus hauseri, Brochothrix thermosphacta, and less frequently Pseudomonas, Erwinia, and Massilia. Opportunistic pathogenic bacteria such as Escherichia coli and Vibrio sp. were found in small quantities. The yeasts Kazachstania servazzii and Debaryomyces hansenii occurred already at 0 days, whereas various species of Candida (Candida zeylanoides, Candida sake, Candida norvegica, and Candida glaebosa) were abundant only after 12 days. These results indicated that the microbiological contaminants overgrowing during the secondary shelf life did not derive from environmental cross-contamination at the opening of the tray but were already present when the packages were opened, highlighting the phases of production up to the packaging as those crucial in managing the safety risk associated to this product.

Identification of Pseudomonas aeruginosa strains isolated from Dorper sheep milk with subclinical-mastitis infection by uniplex PCR using 16S rRNA, lasI/R, gyrB and ecfX genes

Pseudomonas aeruginosa is an opportunistic and versatile pathogenic bacterium that can adapt in various environmental condition, which play a role in multiple virulence factor and resistance to antibiotics. Moreover, molecular identification techniques using single target gene is more susceptible to error and false positive. Thus, the detection of this strain with high specificity and sensitivity is crucial in order to control this pathogenic bacterium. The aim of this study was to evaluate six bacteria strains (13-1, 66-1, 00-1, 46-1, 10-R and 67-1) isolated from Dorper sheep milk and two P. aeruginosa ATCC strains (ATCC BAA-2108 and ATCC27853) for prompt identification of the strains based on uniplex polymerase chain reaction which targeting PA-SS, PA-GS, lasI/R, gyrB and ecfX genes. In the present study, the Dorper sheep milk’s samples (n = 32) were collected and tested with California mastitis test (CMT). Out of 32 milk’s samples, six of the samples were detected with strong mastitis, and thus were continued with inoculation process on selective media Pseudomonas Agar P (for pyocyanin) or F (fluorescein) and MacConkey agar for differentiation. After extraction of the bacteria chromosomal DNA, uniplex PCR amplification were carried out by using 16S rRNA (PA-SS and PA-GS) primers and specific P. aeruginosa genes (lasI/R, gyrB and ecfX) primers. The specificity of the primers was also examined by non-Pseudomonas species as a control for data comparison. Sequence analysis has revealed that six of the isolated samples were confirmed as P. aeruginosa strains with the respective genes sequence confirmed by BLAST and Clustal Omega. From this study, lasI/R, gyrB and ecfX were highly reliable primers with the percentage of identification of more than 95.0% as compared to PA-SS and PA-GS which were less than 90.0%. This study concludes that highly specific and sensitive assay has been developed using lasI/R, gyrB and ecfX targeted genes for the detection of P. aeruginosa strains isolated from fresh sheep milk samples.

Monitoring and evaluation of antibiotic resistance genes in three rivers in northeast China.

Antibiotic resistance genes (ARGs) have become an important public health problem. In this study, we used metagenomic sequencing to analyze the composition of ARGs in selected original habitats of northeast China, comprising three different rivers and riverbank soils of the Heilongjiang River, Tumen River, and Yalu River.Twenty types of ARG were detected in the water samples. The major ARGs were multidrug resistance genes, at approximately 0.5 copies/16S rRNA, accounting for 57.5% of the total ARG abundance. The abundance of multidrug, bacitracin, beta-lactam, macrolide-lincosamide-streptogramin, sulfonamide, fosmidomycin, and polymyxin resistance genes covered 96.9% of the total ARG abundance. No significant ecological boundary of ARG diversity was observed. The compositions of the resistance genes in the three rivers were very similar to each other, and 92.1% of ARG subtypes were shared by all water samples. Except for vancomycin resistance genes, almost all ARGs in riverbank soils were detected in the river water. About 31.05% ARGs were carried by Pseudomonas. Opportunistic pathogenic bacteria carrying resistance genes were mainly related to diarrhea and respiratory infections. Multidrug and beta-lactam resistance genes correlated positively with mobile genetic elements (MGEs), indicating a potential risk of diffusion.The composition of ARGs in three different rivers was similar, indicating that climate plays an important role in ARG occurrence. ARG subtypes in river water were almost completely the same as those in riverbank soil. ARGs had no significant geographical distribution characteristics. Many ARGs were carried by human pathogenic bacteria related to diarrhea and respiratory infections, such as Pseudomonas aeruginosa and Aeromonas caviae. In general, our results provide a valuable dataset of river water ARG distribution in northeast China. The related ecological and geographical distribution characteristics should be further explored.

Dietary S. maltophilia induces supersized lipid droplets by enhancing lipogenesis and ER-LD contacts in C. elegans

ABSTRACT Dietary and symbiotic bacteria can exert powerful influence on metazoan lipid metabolism. Recent studies have emerged that microbiota have a role in animal obesity and related health disorders, but the mechanisms by which bacteria influence lipid storage in their host are unknown. To reduce the complexity of the relationship between gut microbiota and the host, Caenorhabditis elegans (C. elegans) has been chosen as a model organism to study interspecies interaction. Here, we demonstrate that feeding C. elegans with an opportunistic pathogenic bacterium Stenotrophomonas maltophilia (S. maltophilia) retards growth and promotes excessive neutral lipid storage. Gene expression analysis reveals that dietary S. maltophilia induces a lipogenic transcriptional response that includes the SREBP ortholog SBP-1, and fatty acid desaturases FAT-6 and FAT-7. Live imaging and ultrastructural analysis suggest that excess neutral lipid is stored in greatly expanded lipid droplets (LDs), as a result of enhanced endoplasmic reticulum (ER)-LD interaction. We also report that loss of function mutations in dpy-9 in C. elegans confers resistance to S. maltophilia. Dietary S. maltophilia induces supersized LDs by enhancing lipogenesis and ER-LD contacts in C. elegans. This work delineates a new model for understanding microbial regulation of metazoan physiology.

Case report of enterobacter hormaechei in sheep with respiratory disease and death

BackgroundEnterobacter hormaechei is typically a opportunistic pathogenic bacterium in humans, and no pathological change of of Enterobacter hormaechei in diseased sheep has previously been documented.Case presentationThree free-range, four-month-old female sheep were ill with respiratory disease and died three days after receiving treatment with ceftiofur sodium. A frozen lung sample of one sheep was studied using bacterium isolation, and lung samples of the other two sheep were collected and analyzed by histopathological examination and bacterium isolation. The 16S rRNA gene sequences and biochemical characteristics of the isolates were analyzed. All results showed the isolated strain to be Enterobacter hormaechei. Phylogenetic analysis of the 16S rRNA sequence showed three representative strains were most closely related to the strains isolated from calf. Antimicrobial sensitivity tests indicated that no sensitivity to the β-lactam antimicrobials involved in treatment of sheep respiratory disease in China. Detection of the genes responsible for β-lactam resistance showed that all three isolates from sheep harbor blaSHV and blaKPC. Interstitial pneumonia, bronchial epithelial cells shedding, and massive mucous secretion were observed in the lung histopathological sections. Immunohistochemical staining showed that specific staining was mainly limited to the alveoli and alveolar septum.ConclusionsThis appears to be the first report of pathological changes in lungs of sheep with respiratory disease and death associated with Enterobacter hormaechei.

Screening of antibacterial activities of Bacillus spp. isolated from the Parangkusumo coastal sand dunes, Indonesia

Abstract Background: The emergence of multidrug-resistant bacteria because of poor understanding of the issue and the misuse of antibiotics has become global health concern. Therefore, the discovery of novel antibacterial drugs is urgently needed. New antibacterial compounds may be found in the Bacillus species, which are abundant in sand dune ecosystems. Herein, we examined samples from the Parangkusumo coastal sand dunes in Indonesia. Methods: Samples were collected from three areas in the sand dunes (the area closest to the sea, the core area of sand dunes, and the area farthest from the sea). The samples were inoculated on Luria Bertani agar. Morphological and molecular identification was performed on the basis of 16S rRNA. The samples’ antimicrobial activity was evaluated with the disc diffusion method and compared with that of opportunistic pathogenic bacteria. Results: Five species of Bacillus were successfully isolated from the Parangkusumo coastal sand dunes. To our knowledge, this is the first report of the isolation of Bacillus aryabhattai in Indonesia. All samples showed antimicrobial activity against pathogenic bacteria. B. velezensis and B. subtilis showed antibacterial activity against Gram-positive bacteria, whereas B. aryabhattai and B. megaterium showed antibacterial activity against Gram-negative bacteria, and B. spizizenii showed antibacterial activity toward Gram-positive and Gram-negative bacteria. Conclusion: Five Bacillus species were successfully isolated from the Parangkusumo coastal sand dunes, Indonesia, and all samples showed antimicrobial activity toward opportunistic pathogenic bacteria. The crude antimicrobial compounds from B. megaterium, B. aryabhattai, B. subtilis, and B. spizizenii showed the highest growth-inhibition activity against E. coli, P. aeruginosa, B. cereus, and S. aureus, respectively.

Pseudomonas aeruginosa associated pulmonary infections and in vitro amplification virulent rhamnolipid (rhlR) gene.

Pseudomonas aeruginosa is a common opportunistic pathogenic bacterium with the ability to develop a strong communication pathway by quorum sensing system and different virulent factors. Among the various important secretions of P. aeruginosa rhamnolipid is important biological detergent, believed to be involved in the development of the biofilm and intercellular communication. It readily dissolves the lung surfactants that are then easily catalyzed by the phospholipases and in this way is involved in the acute pulmonary infection. research work was designed to investigate virulence and gene associated with virulence in P. aeruginosa responsible for pulmonary infections. In current study polymerase chain reaction (PCR) was used for the detection of the rhlR (rhamnolipid encoding) gene of isolated strains. A number of assays were performed that ensured its virulent behavior. Disc diffusion method was used to check its antibiotic resistance. Isolated strains were resistant to a number of antibiotics applied. It was found that males are more prone to respiratory infections as compared to females. Male members with age of 44-58 and 59-73 are at a higher risk, while females with age of 44-58 are also at a risk of pulmonary infections. Antibiotic resistance was observed by measuring zone of inhibition in strains GCU-SG-M4, GCU-SG-M3, GCU-SG-M5, GCU-SG-M2, GCU-SG-M1 and GCU-SG-M6. GCU-SG-M2 was resistant to fluconazole (FLU), clarithromycin (CLR), cefixime (CFM) and Penicillin (P10). No zone of inhibition was observed. But it showed unusual diffused zone around the Ak and MEM antibiotic discs. rhl R gene and 16s rRNA gene were characterized and analyzed. Findings from current study would help in raising awareness about antibiotic resistance of P. aeruginosa, and also the sequence of rhl R gene can be used as the diagnostic marker sequence to identify the virulent rhl R gene sequence from the samples when isolated from sputum of Pneumonia patients.

Investigating Pathogenicity and Virulence of Staphylococcus pettenkoferi: An Emerging Pathogen.

Staphylococcus pettenkoferi is a coagulase-negative Staphylococcus identified in 2002 that has been implicated in human diseases as an opportunistic pathogenic bacterium. Its multiresistant character is becoming a major health problem, yet the pathogenicity of S. pettenkoferi is poorly characterized. In this study, the pathogenicity of a S. pettenkoferi clinical isolate from diabetic foot osteomyelitis was compared with a Staphylococcus aureus strain in various in vitro and in vivo experiments. Growth kinetics were compared against S. aureus, and bacteria survival was assessed in the RAW 264.7 murine macrophage cell line, the THP-1 human leukemia monocytic cell line, and the HaCaT human keratinocyte cell line. Ex vivo analysis was performed in whole blood survival assays and in vivo assays via the infection model of zebrafish embryos. Moreover, whole-genome analysis was performed. Our results show that S. pettenkoferi was able to survive in human blood, human keratinocytes, murine macrophages, and human macrophages. S. pettenkoferi demonstrated its virulence by causing substantial embryo mortality in the zebrafish model. Genomic analysis revealed virulence factors such as biofilm-encoding genes (e.g., icaABCD; rsbUVW) and regulator-encoding genes (e.g., agr, mgrA, sarA, saeS) well characterized in S. aureus. This study thus advances the knowledge of this under-investigated pathogen and validates the zebrafish infection model for this bacterium.

Disseminated Nocardia farcinica involves the spinal cord: a case report and review of the literature

BackgroundNocardia is a relatively rare opportunistic pathogenic bacteria group, commonly seen in patients with immunocompromised or defective immune system. It can affect multiple organs of the body and cause disseminated infection, among which most occurs in the lung, secondly in the nervous system, soft tissues, rare in the spinal cord and pituitary. No case has been reported involving lung, spinal cord, skin and pituitary gland at the same time.Case presentationWe report a 55-year-old female with Nocardia infection involving the lung, skin, spinal cord, and pituitary gland. The patient underwent a full set of imaging examinations and showed typical imaging findings. Chest computed tomography (CT) showed multiple nodules with cavities in the lungs. The magnetic resonance imaging (MRI) of the vertebral body showed abnormal signal of the entire spinal cord with cavity formation and ring enhancement. The subcutaneous nodules of the abdomen were punctured under ultrasound. Through the etiological tissue culture of subcutaneous nodules and the second generation sequencing of cerebrospinal fluid, the diagnosis was finally confirmed.ConclusionDisseminated Nocardiosis is an uncommon disease. This article will report a rare case of disseminated Nocardiosis simultaneously involving the lung, spinal cord, subcutaneous soft tissue and pituitary gland, especially with neuropathy as the initial symptom. Imaging is helpful for the early diagnosis of the disease and pathological and microbiological examinations are helpful for its confirming.

Gut microbiota in burned patients with Clostridioides difficile infection

BackgroundThe survival rate of patients with severe burn is positively associated with increasing the incidence of the Clostridioides difficile (C. difficile) infection (CDI). The surviving rate of severe burn patients now has an improved but the incidence of Clostridioides difficile (C. difficile) infection (CDI) has been continues increasing during recent two decades.This study assessed the molecular typing and phenotypic characterization isolates of C. difficile in burn patients with diarrhea, as well as environmental and skin infections with C. difficile spores at a referral burn hospital in Isfahan, Iran. It mainly aimed to evaluate the dominant bacterial structure in the gut microbiome of burned subjects with and without CDI. MethodsIn general, 309 samples were collected from 189 burned patients with hospital-acquired diarrhea and 120 swabs were collected from the healthcare workers’ dominant hands, different sites of patients’ skin, and medical tools. In addition, C. difficile isolates were characterized considering the existence of antibiotic resistance and toxin genes. Clinical cultures with identification of organisms and antibiotic susceptibility were done. C. difficle isolates were then genotyped and compared to clinical outcomes. Finally, the clinical characteristics of the participants were gathered through their records, and the bacterial targets of the gut microbiome were detected using quantitative real-time polymerase chain reaction (PCR). ResultsBased on the findings, 51 C. difficile isolates were detected from 189 severe burn patients hospitalized in the hospital. Further, PCR amplification tcdB and tcdA showed 23 isolates (12.2%) as toxigenic. Overall, 18.3% (22/120) of skin and environment samples demonstrated a positive result for C. difficile colonization. A low concentration of metronidazole and vancomycin (MIC90, 0.5, and 1.2 mg/L) inhibited all toxigenic C. difficile strains. Moreover, these isolates represented the highest rates of resistance to moxifloxacin and clindamycin (MIC90, 0.5, and 1.6 mg/L). A significantly reduced abundance of Clostridium spp., Bacteroidetes, and Bifidobacterium and an increase in the quantity of Firmicutes was observed in the gastrointestinal microbiome of burn patients (P < 0.01). Burn patients with CDI showed a significant decrease in Faecalibacterium prausnitzii (F. prausnitzii) while higher Akkermansia muciniphila (A. muciniphila) loads in comparison with healthy controls (P < 0.001 and P < 0.05). Contrarily, burned cases displayed increased levels of opportunistic pathogenic bacteria including the members of Enterococcus spp. and Escherichia coli (P < 0.05). ConclusionsDespite appropriate infection control strategies in the burn intensive care unit, CDI remains prevalent in severe burn patients. Eventually, the overgrowth of A. muciniphila and the decreased abundance of F. prausnitzii in burn cases with CDI could be potential predictive microbiome biomarkers in burned patients.