Multidrug-resistant Species Research Articles

A Self-Forming Hydrogel from a Bactericidal Copolymer: Synthesis, Characterization, Biological Evaluations and Perspective Applications

Objects touched by patients and healthcare workers in hospitals may harbor pathogens, including multi-drug resistant (MDR) staphylococci, enterococci (VRE), Escherichia coli, Acinetobacter, and Pseudomonas species. Medical devices contaminated by these pathogens may also act as a source of severe and difficult-to-treat human infections, thus becoming a critical public health concern requiring urgent resolutions. To this end, we recently reported the bactericidal effects of a cationic copolymer (CP1). Here, aiming at developing a bactericidal formulation possibly to be used either for surfaces disinfection or to treat skin infections, CP1 was formulated as a hydrogel (CP1_1.1-Hgel). Importantly, even if not cross-linked, CP1 formed the gel upon simple dispersion in water, without requiring gelling agents or other additives which could be skin-incompatible or interfere with CP1 bactericidal effects in possible future topical applications. CP1_1.1-Hgel was characterized by attenuated-total-reflectance Fourier transform infrared (ATR-FTIR) and UV-Vis spectroscopy, as well as optic and scanning electron microscopy (OM and SEM) to investigate its chemical structure and morphology. Its stability was assessed by monitoring its inversion properties over time at room temperature, while its mechanical characteristics were assessed by rheological experiments. Dose-dependent cytotoxicity studies performed on human fibroblasts for 24 h with gel samples obtained by diluting CP_1.1-Hgel at properly selected concentrations established that the 3D network formation did not significantly affect the cytotoxic profile of CP1. Also, microbiologic investigations carried out on two-fold serial dilutions of CP1-gel confirmed the minimum inhibitory concentrations (MICs) previously reported for the not formulated CP1.Selectivity indices values up to 12 were estimated by the values of LD50 and MICs determined here on gel samples.

Antibacterial Activity of Lemon Juice on Multi-Drug Resistant Klebsiella species Harboring blaOXA-48 Gene

Klebsiella species cause a wide range of infections, and infections caused by multi-drug resistant species have significantly higher rates of morbidity and mortality. Extended spectrum β-lactamase ESBL prodan emergingd carbapenem resistant K. pneumoniae is emerging problem in hospital settings worldwise. However, the distribution of blaOXA-48 in Klebsiella pneumoniae has rarely been described from Nepal. This study was carried out to evaluate in vitro antibacterial activity of lemon juice against clinical isolates of Klebsiella having blaOXA-48 gene. A total of 667 clinical specimens were processed for the identification of Klebsiella species by morphological, cultural and biochemical tests. Methods of antimicrobial susceptibility testing and confirmation of extended spectrum beta lactamase (ESBL) were adopted from the guidelines of the Clinical Laboratory Standard Institute (2018), and blaOXA-48 gene was detected by polymerase chain reaction. The antibacterial activity of lemon juice was assayed using agar well diffusion, and the bactericidal effect of lemon juice was determined by the broth dilution method. Out of 204 culture positive isolates, 29.5% were Klebsiella species of which 16.7% were ESBL producers. Among 19 isolates positive to Modified Hodge test, 68.4% were detected with the plasmid mediated blaOXA-48 gene. The MIC of lemon juice ranged from 12.5-50% (v/v), and the bacteriostatic activity was observed after 6-8 hours of exposure. The tested varieties of lemon juice showed potential inhibitory activity against Klebsiella species indicating that lemon juice has the potential to be used as an antibacterial agent.

Efficacy of chlorhexidine in advanced performance technology formulation in decolonizing the skin using Candida auris skin colonization mouse model

The incidence of Candida auris, an emerging multidrug resistant fungal species, is increasing. The ability of this yeast to colonize the human skin could lead to infections. Identifying agents to reduce the skin fungal burden is critical. Chlorhexidine formulated in a new Advanced Performance Technology formulation (APT-CH) was significantly more effective than untreated controls. Additional studies are warranted.

Prevalence and multidrug resistance of Enterococcus species isolated from chickens at slaughterhouses in Nakhon Ratchasima Province, Thailand.

Enterococcus is a commensal bacteria found in humans and animals, which can cause human nosocomial infections. One of the most contaminated enterococcal sources is poultry meat. Therefore, this study estimated the prevalence and antimicrobial resistance (AMR) profile of Enterococcus from chickens and their meat products at local slaughterhouses in Nakhon Ratchasima Province, Thailand. From January 2021 to March 2022, 558 samples from 279 cloacal swabs and breast meat were collected from 31 local slaughterhouses in the area. Then, the samples were screened for Enterococcus using modified de Man, Rogosa, and Sharpe agar. Next, selected Gram-positive, catalase-negative, and cocci-shaped colonies were investigated for enterococcal confirmation using Enterococcosel Agar (EA). We also cultivated the samples directly on EA. However, the disk diffusion method was used to investigate positive Enterococcus resistance profiles to 16 antimicrobial agents. Finally, selected phenotypic multidrug-resistant (MDR) Enterococcus isolates were further assessed to identify AMR genes by polymerase chain reaction. Investigations showed that the prevalence of Enterococcus isolates from the chicken cloacal swabs and meat samples were 29.75% (83/279) and 28.32% (78/279), respectively. Most Enterococcus positive isolates were resistant to colistin, followed by cefoxitin, cephalexin, and streptomycin. These isolates also showed a prevalence of MDR species (65.22%; 105/161) and 66 patterns. Furthermore, selected MDR Enterococcus (MDRE) from cloacal swabs and breast meat were positive for the resistant extended-spectrum beta-lactamase TEM genes at 71.43% (20/28) and 78.26% (18/23), respectively, whereas other AMR genes detected in the selected MDR enterococci from the cloacal swabs and breast meat were beta-lactamase TEM (bla TEM [0%, 1.96%]), Class 1 integrase (intI1 [14.28%, 0%]), colistin (mrc-1 [3.57%, 0%]), and vancomycin (vanA [14.28%, 0%]). This study indicated that phenotypic MDRE correlated with extended-spectrum beta-lactamase TEM gene presence, leading to an AMR reservoir that can be transferred to other bacteria.

Extracellularly Released Molecules by the Multidrug-Resistant Fungal Pathogens Belonging to the Scedosporium Genus: An Overview Focused on Their Ecological Significance and Pathogenic Relevance.

The multidrug-resistant species belonging to the Scedosporium genus are well recognized as saprophytic filamentous fungi found mainly in human impacted areas and that emerged as human pathogens in both immunocompetent and immunocompromised individuals. It is well recognized that some fungi are ubiquitous organisms that produce an enormous amount of extracellular molecules, including enzymes and secondary metabolites, as part of their basic physiology in order to satisfy their several biological processes. In this context, the molecules secreted by Scedosporium species are key weapons for successful colonization, nutrition and maintenance in both host and environmental sites. These biologically active released molecules have central relevance on fungal survival when colonizing ecological places contaminated with hydrocarbons, as well as during human infection, particularly contributing to the invasion/evasion of host cells and tissues, besides escaping from the cellular and humoral host immune responses. Based on these relevant premises, the present review compiled the published data reporting the main secreted molecules by Scedosporium species, which operate important physiopathological events associated with pathogenesis, diagnosis, antimicrobial activity and bioremediation of polluted environments.

Development and in vitro characterization of a humanized scFv against fungal infections.

The resistance and the birth of new intrinsic and multidrug-resistant pathogenic species like C. auris is creating great concern in the antifungal world. Given the limited drug arsenal and the lack of effectiveness of the available compounds, there is an urgent need for innovative approaches. The murine mAb 2G8 was humanized and engineered in silico to develop a single-chain fragment variable (hscFv) antibody against β-1,3-glucans which was then expressed in E. coli. Among the recombinant proteins developed, a soluble candidate with high stability and affinity was obtained. This selected protein is VL-linker-VH oriented, and it is characterized by the presence of two ubiquitin monomers at the N-terminus and a His tag at the C-terminus. This construct, Ub2-hscFv-His, guaranteed stability, solubility, efficient purification and satisfactory recovery of the recombinant product. HscFv can bind β-1,3-glucans both as coated antigens and on C. auris and C. albicans cells similarly to its murine parental and showed long stability and retention of binding ability when stored at 4°, -20° and -80° C. Furthermore, it was efficient in enhancing the antifungal activity of drugs caspofungin and amphotericin B against C. auris. The use of biological drugs as antifungals is limited; here we present a promising hscFv which has the potential to be useful in combination with currently available antifungal drugs.

Environmental surveillance of antimicrobial resistance in a rapidly developing catchment.

Development and spread of AMR from various sources such as hospitals, pharmaceutical industries, animal farms and human habitations is not well understood. We conducted a pilot study to assess the prevalence of AMR by taking a case of rapidly developing catchment in Western India. For this, we selected four sub-catchments/regions with a dominant source of antibiotics, viz. areas with (a) dense poultry farms (4 farms/km2), (b) sparse number of poultry farms (2 farms/km2), (c) agricultural fields and (d) habitation (village). The environmental samples (soil, litter and water) were subjected to Kirby-Bauer/antibiotic disc susceptibility test to assess the resistance pattern in the bacterial species. Preliminary investigations showed the presence of seven multidrug-resistant bacterial species in the litter from poultry farms, with five species having a MAR index greater than 0.2. No evidence of AMR was observed in the vicinity (water and soil) of the poultry farms. This could be attributed to the rigorous disinfection protocols followed at the poultry farms to prevent infection in the fresh batch of chickens. However, in agricultural fields where the litter is used as manure, seven multiple drugs resistant with two species scoring a MAR index greater than 0.2 were observed. MAR index of less than 0.2 was observed for Escherichia coli and Enterobacter species isolated from village and control site (soil), respectively, indicating negligible contamination by antibiotics at sub-catchments. This study provides an approach to investigate the effects of multiple factors on the prevalence of AMR at the catchment scale.

Antimicrobial and Antioxidant Activities of Secondary Metabolites of an Endophytic fungus of Azadirachta indica

Background: Recent upsurge in the mortality rate and long hospital stays as a result of antimicrobial resistance caused by multi-drug resistant bacteria is a huge burden to public health sector. Intensive search for more effective and newer agents to deal with these problems. Endophytes are a novel source of potentially useful medicinal compounds. Aim: The study aimed at evaluating the antimicrobial and antioxidant activities of an endophytic fungus isolated from Azadirachta indica against multi drug resistant bacteria species. Method: Endophytic fungus was isolated from fresh leaves of Azadirachta indica. The fungus was fermented in rice medium, and the secondary metabolites were extracted. The antimicrobial activity of the extract against laboratory strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Bacillus subtilis, Candida albicans, Aspergillus niger) was determined. The fungal extract was also evaluated for antioxidant activity using the DPPH assay method. Using GC-FID analysis, some constituents of the fungal extracted were identified. Result: At 1 and 0.5 mg/mL, the fungal extract demonstrated antibacterial activity against Klebsiella pneumoniae but no activity against the other test microbes. However, the fungal extract of A. indica showed excellent antioxidant activity due to possession of bioactive secondary metabolites. Conclusion: The result of GC-FID showed the presence of Rutin, Lunamarin, Anthocyanin, Catechin, Naringenin, Flavan 3 ol, Sapogernin, Tannin, Spartein, Naringin, Flavonones, Steroids, Kaemferol, Cyanogenic glycoside, Phytate, Epicatechin, Reseveratol, Cardic glycoside and Epihedrine at different concentrations. This study reveals the dynamic potentials of the endophytic fungus of A. indica as the bedrock of naturally occurring bioactive agent. 
 Keywords: Azadirachta indica, endophytes, GC-FID, secondary metabolites, medicinal plants, phytochemicals.

EMERGENCE OF EXTENDED SPECTRUM BETA-LACTAMSE (ESBL) PRODUCING CITROBACTER - A NOSOCOMIAL PATHOGEN OF GREAT CONCERN

Background: Multidrug resistant Citrobacter species are emerging as nosocomial pathogens. Among the Citrobacter species, C. freundii is the most frequent isolate recovered from various clinical samples. Aims and objectives: i) To determine the frequency of isolation of Citrobacter from various clinical samples. ii) To analyse the antibiogram of Citrobacter species with special reference to ESBL production. The prospecti Method: ve study was carried out for a period of one year. The clinical samples were subjected to culture and sensitivity as per standard conventional methods and automated Vitek 2 compact system. The frequency of recovery of Citrobacter species was 6.44%, Results: of which the predominant was C. freundii (86%). Isolation was maximum from indoor patients (78.83%), the commonest sample being pus (25.9%) followed by urine (22.5%). The ESBL production was detected in 30.03% cases. Nosocomial infections due Conclusion: to ESBL producing Citrobacter species calls for the need of implementation of effective infection control measures, thus limiting the burden of this superbug.

In Vitro Activity of Essential Oils Distilled from Colombian Plants against Candidaauris and Other Candida Species with Different Antifungal Susceptibility Profiles.

Multi-drug resistant species such as Candida auris are a global health threat. This scenario has highlighted the need to search for antifungal alternatives. Essential oils (EOs), or some of their major compounds, could be a source of new antifungal molecules. The aim of this study was to evaluate the in vitro activity of EOs and some terpenes against C. auris and other Candida spp. The eleven EOs evaluated were obtained by hydro-distillation from different Colombian plants and the terpenes were purchased. EO chemical compositions were obtained by gas chromatography/mass spectrometry (GC/MS). Antifungal activity was evaluated following the CLSI standard M27, 4th Edition. Cytotoxicity was tested on the HaCaT cell line and fungal growth kinetics were tested by time–kill assays. Candida spp. showed different susceptibility to antifungals and the activity of EOs and terpenes was strain-dependent. The Lippia origanoides (thymol + p-cymene) chemotype EO, thymol, carvacrol, and limonene were the most active, mainly against drug-resistant strains. The most active EOs and terpenes were also slightly cytotoxic on the HaCaT cells. The findings of this study suggest that some EOs and commercial terpenes can be a source for the development of new anti-Candida products and aid the identification of new antifungal targets or action mechanisms.

Finding a Needle in a Haystack - In Silico Search for Environmental Traces of Candida auris.

Candida auris, first described from an ear infection in Japan, is an important emerging multidrug-resistant pathogenic fungal species. Its environmental niche remained a mystery until its isolation from the wetlands of the Andaman Islands, India, in 2020. We screened a subset of the world's largest sequence repository, the Sequence Read Archive at National Center for Biotechnology Information, using a DNA metabarcoding approach based on either the internal transcribed spacer (ITS)1 or ITS2 region of the official primary fungal DNA barcode, to identify potential environmental sources of C. auris. Our search identified 34 matches with partial C. auris ITS sequences from seven metabarcoding studies, providing wider evidence for the presence of C. auris outside human-maintained facilities.

Antibacterial Activity of Metallic Nanoparticles against Multidrug-Resistant Pathogens Isolated from Environmental Samples: Nanoparticles/Antibiotic Combination Therapy and Cytotoxicity Study.

Multidrug-resistant organisms have increased the prevalence of infectious diseases and have become the leading source of death globally. The adverse effects associated with conventional antibiotics cannot be underestimated, and as a result, the quest for antibacterial agents has received great attention over the years. Therefore, the current research was designed to synthesize and examine the antibacterial properties of two metallic nanoparticles, silver nanoparticles (AgNPs) and zinc oxide nanoparticles (ZnONPs), as well as their antibiotic combination therapy against multidrug-resistant bacteria. AgNPs and ZnONPs were synthesized by the coprecipitation method and characterized. Thereafter, their antibacterial activity against multidrug-resistant bacteria was investigated using the microdilution technique. Subsequently, the interactions between the synthesized nanoparticles and antibiotics were evaluated by checkerboard assay. Time-kill assays were carried out to assess bacteriostatic or bactericidal effects, and the cytotoxicity study was carried out by MTT assay. The SEM analysis of AgNPs and ZnONPs were spherical with an average size of 21.03 and 43.37 nm, respectively. FTIR analysis showed the characteristics of the metal-oxygen vibrational band for both materials around 450 cm-1, which indicated the successful synthesis of these antibacterial agents. The EDX characterization revealed Zn and O with 77.89% and 18.24% abundance in ZnONPs and Ag with 95.65% abundance in AgNPs. UV-vis absorption spectra of AgNPs was obtained around 400 nm. ZnONPs showed a moderate antibacterial effect against Enterococcus species with a MIC range of 2.5-5 mg/mL, while AgNPs demonstrated a strong antibacterial effect against the tested bacterial strains with a MIC range of 0.078-0.039 mg/mL. The ZnONPs were found to be cytotoxic against Vero cell lines at the tested concentrations, whereas AgNPs had no cytotoxic effect at lower concentrations. Their combination activities showed synergetic and additive effects. These findings revealed that these synthesized materials could serve as alternate antibacterial agents against multidrug-resistant Acinetobacter baumanni and Enterococcus species.

P028 To Study the Susceptibility of Caspofungin in Azole Resistant Candidemia of High-Risk Neonates of Nicu by E-STRIP (MIC) Method andTime to Think for Preventive Measures

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PMBackgroundThe rise in azole-resistant candidemia among bloodstream infections of critically ill neonates had made treatment choices difficult for neonate ICU clinicians. There is gross evidence of an epidemiological shift to non-albicans Candida. Newer class of antifungal drugs especially Echinocandins (caspofungin) came into real-time practice in azole-resistant Candida causing sepsis.Objective1) To study the azole-resistance in the Candida isolates from the blood sample.2) To develop preventive strategies and protocols.Material and MethodsA total of 222 blood samples collected from NICU from the high-risk neonates with suspected sepsis, who were admitted in the study period and were processed and were evaluated as per the Standard Mycological techniques followed by antifungal susceptibility done according to CLSI guidelines (M44-A2 and M60).ResultsOf 222 blood samples 58 (26.12%) were pure isolates of Candida, of which 17 (29.31%) were C. albicans and 41 (70.68%) were non-albicans Candida. In which C. glabrata (30/41), C. tropicalis (4/41), C. parapsiliosis (6/41), C. krusei (1/41). Maximum resistance was found against fluconazole 39/58 (67.24%) by disc diffusion method. These isolates are maintained and checked for caspofungin and fluconazole susceptibility by the e-strip method in under process (results will be disclosed later).ConclusionThis study concludes that fluconazole resistance is on the rise. A newer class of drugs Echinocandins have come to the rescue. Strict infection control strategies, appropriate preventive, and therapeutic measures such as prophylactic antifungal use, and a restrictive policy of antibiotic use should be implemented by the health care workers and officials in NICU. Care should be taken for emerging multi-drug resistant species like C. auris.

Environmental bacterial and fungal contamination in high touch surfaces and indoor air of a paediatric intensive care unit in Maputo Central Hospital, Mozambique in 2018

SummaryBackgroundThe hospital environment serves as a reservoir of microorganisms which may be associated with healthcare-associated infections (HCAI). The study of environmental contamination with microorganisms is a method for the assessment of hospital environmental hygiene. We sought to evaluate the environmental colonisation of a national reference hospital unit, using the total aerobic colony count (ACC) and the isolated microorganisms, as assessment tools.MethodsA cross-sectional study was conducted in the Paediatric Intensive Care Unit (PICU) of the Hospital Central de Maputo during a four-week period in 2018. Surfaces and air were sampled before and after room cleaning, using swabs and passive air method. Those samples were processed at the microbiology laboratory where total ACC levels were evaluated, and microorganisms were isolated, identified and assessed for antibiotic susceptibility.DiscussionComparison of the total median ACC of the indoor air (287 cfu/m3 before and 195 cfu/m3 after) and surfaces (0.38 cfu/cm2 before and 0.33 cfu/cm2 after) before and after room cleaning did not show significant differences (P>0.05). Microorganisms of epidemiological importance, including coagulase negative staphylococci (CoNS), Klebsiella pneumoniae and Serratia odorifera were isolated and all of these three were multi-drug resistant (MDR).ConclusionThe results showed controlled contamination levels on high touch surfaces in the patient environment and a high level of contamination of the indoor air suggesting deficiencies in the PICU environmental decontamination process. There was evidence of the presence of fungi and MDR species of epidemiological importance in the context of HCAI.

The SET-domain protein CgSet4 negatively regulates antifungal drug resistance via the ergosterol biosynthesis transcriptional regulator CgUpc2a

Invasive fungal infections, which pose a serious threat to human health, are increasingly associated with a high mortality rate and elevated health care costs, owing to rising resistance to current antifungals and emergence of multidrug-resistant fungal species. Candida glabrata is the second to fourth common cause of Candida bloodstream infections. Its high propensity to acquire resistance toward two mainstream drugs, azoles (inhibit ergosterol biosynthesis) and echinocandins (target cell wall), in clinical settings, and its inherent low azole susceptibility render antifungal therapy unsuccessful in many cases. Here, we demonstrate a pivotal role for the SET {suppressor of variegation 3 to 9 [Su(var)3–9], enhancer of zeste [E(z)], and trithorax (Trx)} domain–containing protein, CgSet4, in azole and echinocandin resistance via negative regulation of multidrug transporter–encoding and ergosterol biosynthesis (ERG) genes through the master transcriptional factors CgPdr1 and CgUpc2A, respectively. RNA-Seq analysis revealed that C. glabrata responds to caspofungin (CSP; echinocandin antifungal) stress by downregulation and upregulation of ERG and cell wall organization genes, respectively. Although CgSet4 acts as a repressor of the ergosterol biosynthesis pathway via CgUPC2A transcriptional downregulation, the CSP-induced ERG gene repression is not dependent on CgSet4, as CgSet4 showed diminished abundance on the CgUPC2A promoter in CSP-treated cells. Furthermore, we show a role for the last three enzymes of the ergosterol biosynthesis pathway, CgErg3, CgErg5, and CgErg4, in antifungal susceptibility and virulence in C. glabrata. Altogether, our results unveil the link between ergosterol biosynthesis and echinocandin resistance and have implications for combination antifungal therapy.

A robust ROS generation nanoplatform combating periodontitis via sonodynamic/chemodynamic combination therapy

Periodontitis is a popular bacteria-induced chronic disease with the absence of effective and noninvasive therapeutic strategies. Sonodynamic therapy (SDT), proved to be promising against infections of bacteria especially multidrug-resistant species by producing reactive oxygen species (ROS), has been considered as tremendous potential in antibacterial application for periodontitis treatment. However, the low quantum yield of ROS remains a significant challenge for SDT. In this study, a novel nano-sonosensitizer was prepared for robust ROS generation via growing TiO2 on dendritic large pore mesoporous silica nanoparticles (DLMSNs) followed by deposition of Ag (DT-Ag) and modifying with the quaternary ammonium chitosan (DT-Ag-CS+). In vitro antibacterial effects of DT-Ag-CS+ were investigated in porphyromonas gingivalis (P. gingivalis) which is a well-recognized periodontal pathogenic bacterium, and in vivo anti-periodontitis effects were evaluated using Wistar rats with ligature-induced periodontitis. The obtained DT-Ag-CS+ exhibited excellent SDT and chemodynamic therapy (CDT) performances both in vitro and in vivo, owing to the deposition of noble metal Ag, and greater chance to penetrate into bacterial cells due to the highly positive-charged CS+ on the surface of DT-Ag. Altogether, a multifunctional DT-Ag-CS+ nano-sonosensitizer has shown promising clinical application for combining SDT and CDT against periodontitis.

Synthesis, Characterization and Broad-Spectrum Bactericidal Effects of Ammonium Methyl and Ammonium Ethyl Styrene-Based Nanoparticles.

Untreatable infections, growing healthcare costs, and increasing human mortality due to the rising resistance of bacteria to most of the available antibiotics are global phenomena that urgently require the discovery of new and effective antimicrobial agents. Cationic macromolecules, acting as membrane disruptors, are widely studied, and several compounds, including two styrene-based copolymers developed by us (P5 and P7), have proved to possess potent broad-spectrum antibacterial effects, regardless of the resistance profiles of the bacteria. Here, we first reported the synthesis and physicochemical characterization of new cationic nanoparticles (NPs) (CP1 and OP2), obtained by polymerizing the monomers 4-ammoniummethylstyrene (4-AMSTY) and 4-ammoniumethylstyrene (4-AESTY) hydrochlorides, whose structures were designed using the cationic monomers of P5 and P7 as template compounds. The antibacterial activity of CP1 and OP2 was assessed against several Gram-positive and Gram-negative multi-drug resistant (MDR) pathogens, observing potent antibacterial effects for both CP1 (MICs = 0.1–0.8 µM) and OP2 (MICs = 0.35–2.8 µM) against most of the tested isolates. Additionally, time-killing studies carried out with CP1 and OP2 on different strains of the most clinically relevant MDR species demonstrated that they kill pathogens rapidly. Due to their interesting physicochemical characteristics, which could enable their mutual formulation as hydrogels, CP1 and OP2 could represent promising ingredients for the development of novel antibacterial dosage forms for topical applications, capable of overcoming severe infections sustained by bacteria resistant to the presently available antibiotics.

Evidence of Virulent Multi-Drug Resistant and Biofilm-Forming Listeria Species Isolated from Various Sources in South Africa.

Listeriosis is a foodborne disease caused by Listeria monocytogenes species and is known to cause severe complications, particularly in pregnant women, young children, the elderly, and immunocompromised individuals. The aim of this study was to investigate the presence of Listeria species in food and water using both biochemical and species-specific PCR analysis. L. monocytogenes isolates were further screened for the presence of various antibiotic resistance, virulence, and biofilm-forming determinants profiles using phenotypic and genotypic assays. A total of 207 samples (composed of meat, milk, vegetables, and water) were collected and analyzed for presence of L. monocytogenes using species specific PCR analysis. Out of 267 presumptive isolates, 53 (19.85%) were confirmed as the Listeria species, and these comprised 26 L. monocytogenes, 3 L. innocua, 2 L. welshimeri, and 1 L. thailandensis. The remaining 21 Listeria species were classified as uncultured Listeria, based on 16SrRNA sequence analysis results. A large proportion (76% to 100%) of the L. monocytogenes were resistant to erythromycin (76%), clindamycin (100%), gentamicin (100%), tetracycline (100%), novobiocin (100%), oxacillin (100%), nalidixic acid (100%), and kanamycin (100%). The isolates revealed various multi-drug resistant (MDR) phenotypes, with E-DA-GM-T-NO-OX-NA-K being the most predominant MDR phenotypes observed in the L. monocytogenes isolates. The virulence genes prfA, hlyA, actA, and plcB were detected in 100%, 68%, 56%, and 20% of the isolates, respectively. In addition, L. monocytogenes isolates were capable of forming strong biofilm at 4 °C (%) after 24 to 72 h incubation periods, moderate for 8% isolates at 48 h and 20% at 72 h (p < 0.05). Moreover, at 25 °C and 37 °C, small proportions of the isolates displayed moderate (8–20%) biofilm formation after 48 and 72 h incubation periods. Biofilm formation genes flaA and luxS were detected in 72% and 56% of the isolates, respectively. These findings suggest that proper hygiene measures must be enforced along the food chain to ensure food safety.

Antimicrobial activities of Nardostachys jatamansi extract against multidrug resistant bacterial species

At present, multidrug resistant (MDR) bacteria have become widespread worldwide, leading to high morbidity and mortality rates in bacterial infections. Again, as there is practically no new antimicrobial agent in the pipeline, this will create a threat to humanity for their survival. In this study, we explored the possible antimicrobial action of ethanolic extract of a typical plant of West Bengal, Nardostachys jatamansi, against MDR and American Type Culture Collection (ATCC) strain bacteria. Antimicrobial activities of Nardostachys jatamansi ethanol extract were studied by disc diffusion technique, and then minimum inhibitory concentration (MIC) determination was done by serial dilution in Mueller Hinton broth. Ethanolic extract of Nardostachys jatamansi showed antimicrobial activities with MIC varied between 2.77- 5.82 mg/mL in both MDR and ATCC bacteria. Ethanolic extract of Nardostachys jatamansi is an effective antimicrobial agent on MDR bacteria and may help save the lives of many critically ill patients.

Decoding the antifungal resistance mechanisms in biofilms of emerging, ubiquitous and multidrug-resistant species belonging to the Scedosporium/Lomentospora genera.

Scedosporium/Lomentospora spp. are multidrug-resistant pathogens able to cause diverse types of infections with typical biofilm characteristics, which makes the treatment a hard issue. We deciphered the resistance mechanisms to classical antifungals developed in the biofilm formed by these fungi.