Biological Activities of Essential Oils from Leaves of Paramignya trimera (Oliv.) Guillaum and Limnocitrus littoralis (Miq.) Swingle

Biofilm Formation in Medically Important Candida Species

Worldwide, the number of infections caused by biofilm-forming fungal pathogens is very high. In human medicine, there is an increasing proportion of immunocompromised patients with prolonged hospitalization, and patients with long-term inserted drains, cannulas, catheters, tubes, or other artificial devices, that exhibit a predisposition for colonization by biofilm-forming yeasts. A high percentage of mortality is due to candidemia caused by medically important Candida species. Species of major clinical significance include C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. krusei, and C. auris. The association of these pathogenic species in the biofilm structure is a serious therapeutic problem. Candida cells growing in the form of a biofilm are able to resist persistent therapy thanks to a combination of their protective mechanisms and their ability to disseminate to other parts of the body, thus representing a threat from the perspective of a permanent source of infection. The elucidation of the key mechanisms of biofilm formation is essential to progress in the understanding and treatment of invasive Candida infections.

Minimal Inhibitory Concentrations of Thymol and Carvacrol: Toward a Unified Statistical Approach to Find Common Trends

Thymol and carvacrol are some of the most important and used components of Essential oils (EOs); they are widely studied, and there are much data available in the literature. Their Minimal Inhibitory Concentration (MIC) values found in the literature from 2005 to present were used to assess the bioactivity toward yeasts, molds, Gram-positive bacteria, and Gram-negative bacteria, as well as on some bacterial species/serotypes (Salmonella sp., Escherichia coli, E. coli O157:H7, lactic acid bacteria, Listeria monocytogenes, Staphylococcus aureus, S. epidermidis, etc.) to find possible common trends or differences between the two compounds and among the tested species. The results were quite interesting and pointed out that there is a common range for the MIC of thymol and carvacrol for some bacterial species (150-400 mg/L), with some exceptions to this generalized statement. In addition, the statistics pointed out that bacteria could experience homogeneous (S. epidermidis, E. coli O157:H7) or heterogeneous trends (for example, Salmonella sp.) depending on the existence of possible sub-species or different experimental set-ups. Moreover, this paper suggests that there are some drawbacks and issues that should be solved for the effective use of EOs, which are the strong variability among the microorganisms and the lack of standard protocols and reference strains.

Antimicrobial Secondary Metabolites from the Mangrove Plants of Asia and the Pacific

Microbes such as the White Spot Syndrome Virus account for severe losses in the shrimp farming industry globally. This review examines the literature on the mangrove plants of Asia and the Pacific with antibacterial, antifungal, or antiviral activities. All of the available data published on this subject were collected from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and a library search from 1968 to 2022. Out of about 286 plant species, 119 exhibited antimicrobial effects, and a total of 114 antimicrobial natural products have been identified including 12 with MIC values below 1 µg/mL. Most of these plants are medicinal. The mangrove plants of Asia and the Pacific yield secondary metabolites with the potential to mitigate infectious diseases in shrimp aquaculture.

Myrtle-Functionalized Nanofibers Modulate Vaginal Cell Population Behavior While Counteracting Microbial Proliferation

Vaginal infections affect millions of women annually worldwide. Therapeutic options are limited, moreover drug-resistance increases the need to find novel antimicrobials for health promotion. Recently phytochemicals were re-discovered for medical treatment. Myrtle (Myrtus communis L.) plant extracts showed in vitro antioxidant, antiseptic and anti-inflammatory properties thanks to their bioactive compounds. The aim of the present study was to create novel nanodevices to deliver three natural extracts from leaves, seeds and fruit of myrtle, in vaginal milieu. We explored their effect on human cells (HeLa, Human Foreskin Fibroblast-1 line, and stem cells isolated from skin), resident microflora (Lactobacillus acidophilus) and on several vaginal pathogens (Trichomonas vaginalis, Escherichia coli, Staphylococcus aureus, Candida albicans, Candida kefyr, Candida glabrata, Candida parapsilosis, Candida krusei). Polycaprolactone-Gelatin nanofibers encapsulated with leaves extract and soaked with seed extracts exhibited a different capability in regard to counteracting microbial proliferation. Moreover, these nanodevices do not affect human cells and resident microflora viability. Results reveal that some of the tested nanofibers are interesting candidates for future vaginal infection treatments.

Evaluation of the Antimicrobial and Antivirulent Potential of Essential Oils Isolated from Juniperus oxycedrus L. ssp. macrocarpa Aerial Parts

As a consequence of the worsening situation with multidrug-resistant (MDR) pathogens and a disparity in the commercialization of novel antimicrobial agents, scientists have been prompted to seek out new compounds with antimicrobial activity from a wide range of sources, including medicinal plants. In the present study, the antibacterial, antifungal, anti-virulence, and resistance-modulating properties of the essential oil from the Sardinian endemic Juniperus oxycedrus L. ssp. macrocarpa aerial parts were evaluated. The GC/MS analysis showed that the main compounds in the oil were α-pinene (56.63 ± 0.24%), limonene (14.66 ± 0.11%), and β-pinene (13.42 ± 0.09%). The essential oil showed potent antibacterial activity against Gram-positive bacteria (0.25–2 v/v%) and Salmonella spp. (4 v/v%). The strongest fungicidal activity was recorded against Candida auris sessile cells (median FICI was 0.088) but not against C. albicans biofilms (median FICI was 1). The oil showed potent efflux pump inhibitory properties in the case of Staphylococcus aureus and Escherichia coli. The therapeutic potential of Juniperus may be promising for future more extensive research and in vivo tests to develop new drugs against antibiotic and antifungal resistance.

Origanum vulgare L. essential oil inhibits virulence patterns of Candida spp. and potentiates the effects of fluconazole and nystatin in vitro

Background

Recurrence and resistance of Candida spp. infections is associated with the ability of these microorganisms to present several virulence patterns such as morphogenesis, adhesion, and biofilm formation. In the search for agents with antivirulence activity, essential oils could represent a strategy to act against biofilms and to potentiate antifungal drugs.

Objective

To evaluate the antivirulence effect of Origanum vulgare L. essential oil (O-EO) against Candida spp. and to potentiate the effect of fluconazole and nystatin.

Methods

The effect of O-EO was evaluated on ATCC reference strains of C. albicans and non-albicans Candida species. Minimum inhibitory concentration (MIC) was determined through broth microdilution assay. Adhesion to microplates was determined by crystal violet (CV) assay. An adapted scratch assay in 24-well was used to determine the effect of essential oil on biofilms proliferation. Viability of biofilms was evaluated by MTT reduction assay and through a checkerboard assay we determined if O-EO could act synergistically with fluconazole and nystatin.

Results

MIC for C. albicans ATCC-90029 and ATCC-10231 was 0.01 mg/L and 0.97 mg/L, respectively. For non-albicans Candida strains MIC values were 2.6 mg/L for C. dubliniensis ATCC-CD36 and 5.3 mg/L for C. krusei ATCC-6258. By using these concentrations, O-EO inhibited morphogenesis, adhesion, and proliferation at least by 50% for the strains assayed. In formed biofilms O-EO decreased viability in ATCC 90029 and ATCC 10231 strains (IC50 7.4 and 2.8 mg/L respectively). Finally, we show that O-EO interacted synergistically with fluconazole and nystatin.

Conclusions

This study demonstrate that O-EO could be considered to improve the antifungal treatment against Candida spp.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03518-z.

Lipid A-Ara4N as an alternate pathway for (colistin) resistance in Klebsiella pneumonia isolates in Pakistan

Objectives

This study aimed to explore mechanism of colistin resistance amongst Klebsiella pneumoniae isolates through plasmid mediated mcr-1 gene in Pakistan. Carbapenem and Colistin resistant K. pneumoniae isolates (n  = 34) stored at − 80 °C as part of the Aga Khan University Clinical Laboratory strain bank were randomly selected and subjected to mcr-1 gene PCR. To investigate mechanisms of resistance, other than plasmid mediated mcr-1 gene, whole genome sequencing was performed on 8 clinical isolates, including 6 with colistin resistance (MIC  >  4 μg/ml) and 2 with intermediate resistance to colistin (MIC  >  2 μg/ml).

Results

RT-PCR conducted revealed absence of mcr-1 gene in all isolates tested. Whole genome sequencing results revealed modifications in Lipid A-Ara4N pathway. Modifications in Lipid A-Ara4N pathway were detected in ArnA_ DH/FT, UgdH, ArnC and ArnT genes. Mutation in ArnA_ DH/FT gene were detected in S3, S5, S6 and S7 isolates. UgdH gene modifications were found in all isolates except S3, mutations in ArnC were present in all except S1, S2 and S8 and ArnT were detected in all except S4 and S7. In the absence of known mutations linked with colistin resistance, lipid pathway modifications may possibly explain the phenotype resistance to colistin, but this needs further exploration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05867-3.

Validation of a method of broth microdilution for the determination of antibacterial activity of essential oils

OBJECTIVE

The aim of the present study was to adapt and optimize a broth microdilution method and compare it to the agar dilution method for the evaluation of activity of essential oils from medicinal plants against Gram-negative bacteria. Based on bibliographic research, active and not active oils were selected. The sensitivity and specificity were established as parameters for validation. The comparison between both methods was made using contingency analysis tables, based on the observed frequencies. For both methods, the minimum inhibitory concentration was determined against Escherichia coli strains, in an essential oil concentration range between 0.03 and 0.48% (v/v).

RESULTS

A stable emulsion formation was achieved with the addition of Tween 80 and constant agitation, guaranteeing the continuous contact of oil with bacteria (critical step in the microdilution method). The statistical analysis of results obtained with both methods presented a good sensitivity and specificity (100% in both cases), which let us correctly discriminate between active and non-active oils. The values obtained for the minimal inhibitory concentration were independent of the technique used. Finally, the obtained results show that the validated microtechnique allows important diminishment of time and resources for investigations dealing with essential oils or lipophilic extracts evaluation.

Molecular Epidemiology of Multidrug-Resistant Uropathogenic Escherichia coli O25b Strains Associated with Complicated Urinary Tract Infection in Children

Background: Uropathogenic Escherichia coli (UPEC) has increased the incidence of urinary tract infection (UTI). It is the cause of more than 80% of community-acquired cystitis cases and more than 70% of uncomplicated acute pyelonephritis cases. Aim: The present study describes the molecular epidemiology of UPEC O25b clinical strains based on their resistance profiles, virulence genes, and genetic diversity. Methods: Resistance profiles were identified using the Kirby–Bauer method, including the phenotypic production of extended-spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs). The UPEC serogroups, phylogenetic groups, virulence genes, and integrons were determined via multiplex PCR. Genetic diversity was established using pulsed-field gel electrophoresis (PFGE), and sequence type (ST) was determined via multilocus sequence typing (MLST). Results: UPEC strains (n = 126) from hospitalized children with complicated UTIs (cUTIs) were identified as O25b, of which 41.27% were multidrug resistant (MDR) and 15.87% were extensively drug resistant (XDR). The O25b strains harbored the fimH (95.23%), csgA (91.26%), papGII (80.95%), chuA (95.23%), iutD (88.09%), satA (84.92%), and intl1 (47.61%) genes. Moreover, 64.28% were producers of ESBLs and had high genetic diversity. ST131 (63.63%) was associated primarily with phylogenetic group B2, and ST69 (100%) was associated primarily with phylogenetic group D. Conclusion: UPEC O25b/ST131 harbors a wide genetic diversity of virulence and resistance genes, which contribute to cUTIs in pediatrics.

Novel mesoporous silica nanocarriers containing gold; a rapid diagnostic tool for tuberculosis

Tuberculosis (TB) is major health concern and reason of deaths from decades to current date. Even though with a lot of advancements, diagnostic techniques, and discovery of standard antibiotics TB remains crucial challenge and can create worst scenario for human health in near future. Nanoparticles play emerging role in diagnosis and treatment of TB. In this study, we developed mesoporous silica nanoparticles containing gold (MSNs@GNPs) for rapid diagnosis and treatment of TB. The physicochemical characterization revealed effective surface morphology and particles diameter, that is applicable for in vitro applications. The in vitro antimicrobial analysis revealed that the designed MSNs@GNPs has retained significantly lower minimal inhibitory concentration (MIC) values and can effectively demolish mycobacterium tuberculosis (Mtb). Furthermore, the diagnosis efficiency of the MSNs@GNPs was evaluated by calorimetric analysis. Which demonstrates that MSNs@GNPs can be used for rapid diagnosis of the tuberculosis when applied on in vitro culture of the Mtb. The current study needs further verification on human's clinical samples from tuberculosis patients. However, MSNs@GNPs can be a versatile clinical approach for the rapid diagnosis and clinical treatment of the tuberculosis.

Antibacterial and anti-Trichomonas Vaginalis effects of Rosa Damascena mill petal oil (a persian medicine product), aqueous and hydroalcoholic extracts

Background

Oils in traditional medicine are important products and used routinely for therapeutic purposes. Rose oil (Rosa damascene Mill), a product of Persian medicine, is advised for the treatment of Infectious diseases related to the female genitourinary tract. In the present study, R. damascena petal oil, aqueous, and hydroalcoholic extracts were evaluated for their in vitro antibacterial and anti-Trichomonas vaginalis effects.

Methods

Anti-trichomonas activity evaluation of extracts and oil were assayed by the Homocytometery method. Their antibacterial effects against Escherichia coli, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and clinically isolated Group B Streptococcus were assayed by broth microdilution in 96-well plates.

Results

The MIC of hydroalcoholic and aqueous extracts ranged from 25-50 and 25-100 mg/ml, respectively. Rose oil at all administered doses failed to show any antibacterial activity.

Conclusion

All extracts and oil concentrations showed some degree of growth inhibition activity on T. vaginalis; however, hydroalcoholic extract was more efficient.

The Inhibitory Efficiencies of Geraniol as an Anti-Inflammatory, Antioxidant, and Antibacterial, Natural Agent Against Methicillin-Resistant Staphylococcus aureus Infection in vivo

Introduction

Antibiotics wee widely used as feed additives in animal husbandry. With the increase of drug resistance of bacteria, there is an urgent need to find alternatives to antibiotics. Clinically, methicillin-resistant Staphylococcus aureus (MRSA) infections account for about 25% to 50% of Staphylococcus aureus infections worldwide. Similarly, it is also one of the pathogens that cause serious animal infections.

Methods

We established a mouse model of systemic infection of MRSA to study the preventive effect of geraniol on MRSA and the immunomodulatory effect of geraniol. The mice in the experiment were injected with geraniol by intramuscular injection and were fed intraperitoneally with minimum lethal dose of MRSA. Then, the survival rate, inflammatory cytokines, oxidative stress factors in serum were measured. These values were used to estimate the bacterial load in different organs and to assess histopathological changes in the lungs, liver and kidneys.

Results

The above-mentioned two ways of using geraniol could prevent MRSA infection in vivo in mice and showed a significant dose–response relationship. In other words, geraniol significantly decreased the concentrations of inflammatory cytokines and oxidative stress factors in MRSA-infected mice. At the same time, the level of glutathione peroxidase also increased in a dose–proportional relationship. In the group of mice treated with geraniol, their superoxide dismutase levels were significantly higher than those in the vancomycin. After treatment with geraniol, the burden of MRSA decreased. No obvious histopathological abnormalities were found in the liver and kidney of MRSA-infected mice. In addition, geraniol improved the inflammatory changes in the lungs.

Conclusion

The results indicated that geraniol was a natural substance that could be used as an anti-inflammatory, antioxidant and antibacterial substance to protect mice from MRSA systemic infection. Generally, the research shows that as a natural medicine, geraniol has broad potential in the development and application of antibiotic substitutes.

A Network Pharmacology-Based Investigation to the Pharmacodynamic Material Basis and Mechanisms of the Anti-Inflammatory and Anti-Viral Effect of Isatis indigotica

Purpose

Isatis indigotica (Ii) is a cruciferous herb that is widely distributed in China, and its roots and leaves have been used in two renowned antipyretic detoxicate crude drugs in Chinese Pharmacopoeia, Radix (R) and Folium (F) Isatidis. However, the pharmacodynamic material basis and underlying mechanisms of the herbal efficacy remained to be elucidated.

Methods

Ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was adopted for the chemical profiling of R and F Isatidis. The active ingredients were screened out through the prediction of gastrointestinal absorption and druglikeness analysis using SwissADME. A herb-ingredient-target network was constructed through target prediction of the herbal active ingredients and anti-inflammation or anti-viral properties, followed by protein-protein interaction analysis. Then, the potential relevant signaling pathways were predicted by pathway enrichment. Finally, for verification, RAW 264.7 cell line was adopted to examine the anti-inflammatory and anti-viral activities of 6 representative ingredients in Ii.

Results

Seventy-three compounds have been identified from Ii through UPLC-Q-TOF-MS. A total of 17 potential active ingredients were screened through pharmacokinetics and drug-likeness evaluation using SwissADME. It was shown that key targets might include TNF, AKT1, SRC, IL2, CASP9, and CASP3 in our herb-ingredient-target network, and isovitexin, a flavonoid, tended to participate in the inflammatory response, indoles were more likely to affect the cell proliferation processes, and lignans might have a broader affinity to key targets than the other active ingredients, such as regulating immune system (targeting IL-2) and PI3K-Akt signaling pathway. In vitro, indigo and secoisolariciresinol diglucoside markedly reduced TNF-α expression in Poly (I: C)-incubated cells. Isovitexin significantly inhibited TNF-α expression, and isatin treatment markedly reduced IL-1β expression in LPS-incubated cells.

Conclusion

As the pharmacodynamics material basis of Ii, indoles, lignans, and flavonoids are believed to confer beneficial properties through various cellular aspects with multiple signaling pathways involved.

Antimicrobial Resistance Mechanisms and Virulence of Colistin- and Carbapenem-Resistant Acinetobacter baumannii Isolated from a Teaching Hospital in Taiwan

Acinetobacter baumannii, a Gram-negative bacterium, is an important nosocomial pathogen. Colistin-resistant A. baumannii is becoming a new concern, since colistin is one of the last-line antibiotics for infections by carbapenem-resistant A. baumannii. From 452 carbapenem-resistant isolates collected in a teaching hospital in Taipei, Taiwan, we identified seven that were resistant to colistin. Carbapenem resistance in these isolates is attributed to the presence of carbapenemase gene bla_OXA-23 in their genomes. Colistin resistance is presumably conferred by mutations in the sensor kinase domain of PmrB found in these isolates, which are known to result in modification of colistin target lipid A via the PmrB-PmrA-PmrC signal transduction pathway. Overexpression of pmrC, eptA, and naxD was observed in all seven isolates. Colistin resistance mediated by pmrB mutations has never been reported in Taiwan. One of the seven isolates contained three mutations in lpxD and exhibited an altered lipopolysaccharide profile, which may contribute to its colistin resistance. No significant difference in growth rates was observed between the isolates and the reference strain, suggesting no fitness cost of colistin resistance. Biofilm formation abilities of the isolates were lower than that of the reference. Interestingly, one of the isolates was heteroresistant to colistin. Four of the isolates were significantly more virulent to wax moth larvae than the reference.

An Investigation of the Male Genitourinary Abscess Originated from Urinary Tract in a Tertiary Hospital, Shanghai, China, from 2004 to 2019

Background

Male genitourinary abscess is one of the serious complications of urinary tract infections (UTIs). There were few researches on the clinical and pathogenic characteristics of male genitourinary abscess.

Patients and Methods

A retrospective observational study was conducted between January 2004 and April 2019. Male patients with genitourinary abscess originated from urinary tract, including sites of scrotum, testis, epididymis, spermatic cord, and prostate, were enrolled. Clinical and microbial records were collected and analyzed, and antimicrobial susceptibility testings were performed according to CLSI standard. Whole-genome sequencing was applied to detect the β-lactamase genes and virulence genes, as well as to determine the multilocus-sequence typing (MLST) of the collected Klebsiella pneumoniae (K. pneumoniae) isolates.

Results

A total of 22 male patients were included. The main clinical symptoms were fever (86.4%), scrotal swelling (68.2%), local skin warmth (59.1%) and ulceration (45.5%). Urinary irritation was often presented in prostate involved abscess. Ultrasound features had a 94.7% positive rate. Surgical treatment, including abscess drainage, was helpful to the prognosis. No matter where the specimens obtained from, including blood, urine or pus, multidrug-resistant K. pneumoniae was the dominant (11 cases, 50.0%) microorganism in positive cultures. Nine of eleven K. pneumoniae isolates had been preserved and recovered. As for MLST typing, all the nine available isolates of K. pneumoniae belonged to the ST11 type and characterized with bla_KPC-2 carbapenemase gene. Virulence genes rmpA2, ybtS, kfuC, wzi, aerobactin genes (iucABCD and iutA) and type 3 fimbriae genes (mrkAD) were identified in all the K. pneumoniae isolates.

Conclusion

It seemed that more patients under 35 years old were vulnerable to genitourinary abscess. There was an increasing trend that multidrug-resistant K. pneumoniae isolates with multiple virulence genes were involved in male genitourinary abscess. Prompt and proper antibiotic use, combined with adequate drainage of the abscess, was important to prognosis.

Progress of Plant Medicine Derived Extracts and Alkaloids on Modulating Viral Infections and Inflammation

Viral infectious diseases are serious threats to human health in both developing and developed countries. Although there is the continued development of new drugs from synthetic sources as antiviral agents, medicinal plants continue to provide the basic raw materials for some of the most important antiviral drugs. Alkaloids are a class of pharmacologically active plant compounds that are usually alkaline in nature. In this review, we tried to summarize recent progress in herb-based antiviral research, the advantages of using active plant compounds as antiviral agents, and the inflammatory responses initiated by alkaloids, based on the literature from 2009 to 2019, for the treatment of conditions, including influenza, human immunodeficiency virus, herpes simplex virus, hepatitis, and coxsackievirus infections. Articles are retrieved from PubMed, Google Scholar, and Web of Science using relevant keywords. In particular, the alkaloids from medicinal plants responsible for the molecular mechanisms of anti-inflammatory actions are identified and discussed. This review can provide a theoretical basis and approaches for using various alkaloids as antiviral treatments. More research is needed to develop alkaloidal compounds as antiviral therapeutic agents and potential regulators of the anti-inflammatory response.

Antibacterial and Antimicrobial Effects of Xanthorrhizol in the Prevention of Dental Caries: A Systematic Review

Background

Xanthorrhizol is one of the numerous phytochemicals whose pharmacological benefits have been explored for its antibacterial and antimicrobial effects. In light of the role bacteria play for initiating tooth decay, this present systematic review assessed xanthorrhizol’s effect against dental caries.

Methods

The electronic databases including Pubmed, Scopus and Embase were searched up to September 2020, Studies examining the antibacterial and antimicrobial effects of xanthorrhizol in the prevention and treatment of dental caries.

Results

Eleven studies met the criteria for final inclusion. Findings from these studies showed that xanthorrhizol showed significant inhibition of notable caries causing bacteria including Streptococcus mutans, Streptococcus sanguinis, Enterococcus faecalis and Bacillus cereus. Furthermore, there was no reported toxicity. However, it could not selectively target the growth of cariogenic bacteria.

Conclusion

So far, studies exploring the use of xanthorrhizol as a potential drug for the prevention and treatment of dental caries have shown promising outcomes. However, more work needs to be done especially in areas such as optimal dose or concentration, in addition, in vitro, in vivo and clinical studies and selective targeting of cariogenic bacteria has been performed.

In vitro and in vivo Effect of Antimicrobial Agent Combinations Against Carbapenem-Resistant Klebsiella pneumoniae with Different Resistance Mechanisms in China

Objective

This study aimed to evaluate the in vitro and in vivo effects of different combinations of antimicrobial agents against carbapenemase-producing and non-producing Klebsiella pneumoniae from China.

Methods

A checkerboard assay of meropenem (MEM), amikacin (AK), tigecycline (TGC), colistin (COL) and their combinations was carried out against 58 clinical carbapenem-resistant K. pneumoniae (CRKp) isolates, including 11 carbapenemase-non-producing K. pneumoniae isolates and 21 isolates producing KPC-2 enzyme, 11 NDM-1, 13 IMP, one VIM-1 and one OXA-48. The checkerboard assay was analyzed by the fractional inhibitory concentration index (FICI). A time-kill assay and Galleria mellonella infection model were conducted to evaluate the in vitro and in vivo effects of the four drugs alone and in combination.

Results

In the checkerboard assay, TGC+AK and MEM+AK combinations showed the highest synergistic effect against KPC-2 and NDM-1 carbapenemase-producing isolates, with synergy+partial synergy (defined as FICI <1) rates of 76.2% and 71.4% against KPC-2 producers, and 54.5% and 81.8% against NDM-1 producers. TGC+AK and MEM+COL combinations showed the highest rate of synergistic effect against IMP-producing isolates. Against carbapenemase-non-producing isolates, TGC+COL and TGC+AK combinations showed the highest rate of synergy effect (63.6% and 54.5%). MEM+AK showed a synergistic effect against one VIM-1 producer (FICI=0.31) and an additivite effect (FICI=1) against one OXA-48 producer. In the time-kill assay, COL+AK, COL+TGC, COL+MEM and AK+TGC showed good synergistic effects against the KPC-2-producing isolate D16. COL+MEM and COL+TGC combinations showed good effects against the NDM-1-producing isolate L13 and IMP-4-producing isolate L34. Against the carbapenemase-non-producing isolate Y105, MEM+TGC and COL+AK showed high synergistic effects, with log₁₀CFU/mL decreases of 6.2 and 5.5 compared to the most active single drug. In the G. mellonella survival assay, MEM-based combinations had relatively high survival rates, especially when combined with colistin, against KPC-2 producers (90% survival rate) and with amikacin against metallo-beta-lactamase producers (95-100% survival rate).

Conclusion

Our study suggests that different antimicrobial agent combinations should be considered against CRKp infections with different resistance mechanisms.

Clinical Impact and Risk Factors of Nonsusceptibility to Third-Generation Cephalosporins Among Hospitalized Adults with Monomicrobial Enterobacteriaceae Bacteremia in Southern Taiwan: A Multicenter Study

Background

Reducing the effectiveness of broad-spectrum cephalosporins against Enterobacteriaceae infections has been recognized. This study aimed to investigate risk factors and clinical significance of third-generation cephalosporin nonsusceptibility (3GC-NS) among the cases of monomicrobial Enterobacteriaceae bacteremia (mEB) at regional or district hospitals.

Methods

The study was conducted at three hospitals in southern Taiwan between Jan. 2017 and Oct. 2019. Only the first episode of mEB from each adult (aged ≥20 years) was included. The primary outcome was in-hospital crude mortality.

Results

Overall there were 499 episodes of adults with mEB included, and their mean age was 74.5 years. Female predominated, accounting for 53% of all patients. Escherichia coli (62%) and Klebsiella pneumoniae (21%) were two major causative species. The overall mortality rate was 15% (73/499), and patients infected by 3GC-NS isolates (34%, 172/499) had a higher mortality rate than those by 3GC-susceptible isolates (66%, 327/499) (21% vs 11%, P=0.005). By the multivariate analysis, 3GC-NS was the only independent prognostic determinant (adjusted odds ratio [AOR], 1.78; P=0.04). Of note, male (AOR 2.02, P=0.001), nosocomial-acquired bacteremia (AOR 2.77, P<0.001), and usage of nasogastric tube (AOR 2.01, P=0.002) were positively associated with 3GC-NS, but P. mirabilis bacteremia (AOR 0.28, P=0.01) and age (AOR 0.98, P=0.04) negatively with 3GC-NS.

Conclusion

For adults with Enterobacteriaceae bacteremia, 3GC-NS signifies a significant prognostic impact. Efforts to rapid identification of such antimicrobial resistance profiles should be incorporated into antimicrobial stewardship programs to achieve favorable outcomes.

Evaluation of Anti-Biofilm Capability of Cordycepin Against Candida albicans

Introduction

The opportunistic pathogen Candida albicans can form biofilms, resulting in drug resistance with great risk to medical treatment.

Methodology

We investigated the ability of C. albicans to form biofilms on different materials, as well as the inhibitory and eradicating effects of cordycepin on biofilm. The action mechanism of cordycepin against biofilm was studied by crystal violet staining, XTT [2, 3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction method, phenol-sulfuric acid method, cellular superficial hydrophobicity (CSH) assay, and confocal laser scanning microscope observation. We also evaluated the acute toxicity of cordycepin in vivo.

Results

The results showed facile formation of biofilms by C. albicans on polypropylene. The 50% minimum inhibitory concentration (MIC₅₀) of cordycepin was 0.062 mg/mL. A concentration of 0.125 mg/mL significantly decreased biofilm formation, metabolic activity, secretion of extracellular polysaccharides, and relative CSH. Cordycepin could inhibit biofilm formation at low concentration without affecting fungal growth. In addition, cordycepin effectively eradicated 59.14% of mature biofilms of C. albicans at a concentration of 0.5 mg/mL. For acute toxicity, the LD₅₀ (50% of lethal dose) of cordycepin was determined as higher than 500 mg/kg for mice.

Conclusion

The results of this study show that cordycepin significantly inhibited and eradicated biofilms by decreasing metabolic activity, the ratio of living cells, the hydrophobicity, and damaging the extracellular polysaccharides of biofilm. These findings should facilitate more effective application of cordycepin and suggest a new direction for the treatment of fungal infections.

Molecular Epidemiology and Characterization of Carbapenem-Resistant Klebsiella pneumoniae Isolated from Urine at a Teaching Hospital in Taiwan

Urinary tract infections (UTIs) are common in clinics and hospitals and are associated with a high economic burden. Enterobacterium Klebsiella pneumoniae is a prevalent agent causing UTIs. A high prevalence of carbapenem-resistant K. pneumoniae (CRKP) has emerged recently and is continuing to increase. Seventeen urinary CRKP isolates collected at a teaching hospital in Taiwan from December 2016 to September 2017 were analyzed to elucidate their drug resistance mechanisms. Two-thirds of the isolates were obtained from outpatients. Antimicrobial susceptibility tests demonstrated multidrug resistance in all the isolates. Multilocus sequence typing analysis showed high diversity among the isolates. PCR analysis demonstrated the presence of carbapenemases in three isolates. All isolates carried at least one other extended-spectrum β-lactamase, including TEM, DHA, and CTX-M. Fifteen isolates contained mutations in one of the outer membrane porins that were assessed. The expression levels of the acrB and/or oqxB efflux pump genes, as determined by qRT-PCR, were upregulated in 11 isolates. Six isolates might have utilized other efflux pumps or antimicrobial resistance mechanisms. These analyses demonstrated a highly diverse population and the presence of complex resistance mechanisms in urinary isolates of K. pneumoniae.

KO. Phytochemical Screening and Potential Antibacterial Activity of Defatted and Nondefatted Methanolic Extracts of Xao Tam Phan (Paramignya trimera (Oliv.) Guillaum) Peels against Multidrug-Resistant Bacteria

Xao tam phan (Paramignya trimera (Oliv.) Guillaum) is a traditional herbal medicine in Vietnam. Previous investigations reported mainly compounds and bioactivities of roots, stems, and leaves while there is limited information about those of fruits. This study aims to reveal the difference in the chemical profile of defatted peel (DP) and nondefatted peel (NDP) methanolic extracts of P. trimera using colorimetric reactions and liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) analysis. We also showed the potential antibacterial activity of two extracts against clinically isolated bacteria strains including P. aeruginosa, Salmonella sp., and S. aureus with the MIC values < 100 μg/mL. This preliminary result proves the traditional usage of this herbal medicine and can be helpful for further investigation on the isolation and identification of the new compounds in P. trimera peels.

Thymol Nanoemulsion: A New Therapeutic Option for Extensively Drug Resistant Foodborne Pathogens

Foodborne pathogens have been associated with severe and complicated diseases. Therefore, these types of infections are a concern for public health officials and food and dairy industries. Regarding the wide-spread multidrug resistant (MDR) and extensively drug resistant (XDR) foodborne pathogens such as Salmonella Enteritidis (S. Enteritidis), new and alternative therapeutic approaches are urgently needed. Therefore, we investigated the antimicrobial, anti-virulence, and immunostimulant activities of a stable formulation of thymol as thymol nanoemulsion in an in vivo approach. Notably, treatment with 2.25% thymol nanoemulsion led to a pronounced improvement in the body weight gain and feed conversion ratio in addition to decreases in the severity of clinical findings and mortality percentages of challenged chickens with XDR S. Enteritidis confirming its pronounced antimicrobial activities. Moreover, thymol nanoemulsion, at this dose, had protective effects through up-regulation of the protective cytokines and down-regulation of XDR S. Enteritidis sopB virulence gene and interleukins (IL)-4 and IL-10 cytokines as those hinder the host defenses. Furthermore, it enhanced the growth of gut Bifidobacteria species, which increases the strength of the immune system. For that, we suggested the therapeutic use of thymol nanoemulsion against resistant foodborne pathogens. Finally, we recommended the use of 2.25% thymol nanoemulsion as a feed additive for immunocompromised individuals as well as in the veterinary fields.

Microbial Contamination of Chicken Litter Manure and Antimicrobial Resistance Threat in an Urban Area Setting in Cameroon

We conducted a pilot study to assess microbiological safety of chicken litter, an affordable organic and main fertilizer used in Cameroon and worldwide. A convenience sampling of 26 farms was done and a questionnaire was administered. Samples of litter were aseptically collected. E. coli and Salmonella spp. were isolated using CLSI standards. Antibiotic susceptibility testing was performed using the disc diffusion method and a micro broth dilution method for colistin. In broiler farms, 90% of participating farmers gave antibiotic prophylaxis. The prevalence of E. coli and Salmonella spp. was 59.1% and 15.5%, respectively. All E. coli isolates were multidrug resistant as well as 36.4% for Salmonella spp. No resistance was found against cefepime and imipenem. All Salmonella spp. tested were found sensitive to colistin while 26.7% of E. coli spp. were colistin resistant. Contamination of chicken litter may be an underestimated source of antimicrobial resistance (AMR) transmission towards animals, humans and the environment with multidrug resistant E. coli and Salmonella spp. This shows the need and opportunity for a One Health approach in AMR surveillance and control in Cameroon. Continued surveillance in chicken litter would enable monitoring of AMR risks and trends.

Clinical and Microbiological Characteristics of Invasive and Hypervirulent Klebsiella pneumoniae Infections in a Teaching Hospital in China

Purpose

To investigate the clinical and microbiological characteristics of invasive and hypervirulent Klebsiella pneumoniae (HvKP) in a teaching hospital in Southern China.

Patients and Methods

A total of 495 non-repetitive K. pneumoniae strains were isolated from Dongguan People’s Hospital affiliated to Southern Medical University in 2018. Multivariate analysis was performed using the patients’ clinical data to identify the risk factors for HvKP.

Results

Eighty-one isolates were HvKP (16.4%, 81/495), of which 43 (53.1%) were invasive HvKP, whereas 38 (46.9%) were non-invasive HvKP. The incidence of extended spectrum beta-lactamases (ESBLs) in HvKP and classic K. pneumoniae (cKP) were 7.4% (6/81) and 28.0% (116/414), respectively (p<0.05). Multivariate analysis indicated that diabetes mellitus (odds ratio [OR]=12.849, 95% confidence interval [CI]: 1.494–110.511, P=0.020) was an independent risk factor for invasive HvKP infection. Altogether, 51.2% (22/43) of invasive HvKP infections were treated with antimicrobial therapy combined with surgical drainage, and achieved good prognosis. K1-ST23 HvKP accounted for a higher proportion of invasive infections than non-invasive infections (P<0.05), but there was no statistical difference in the prognosis between the two groups (P>0.05). The most prevalent virulence genes in HvKP were rmpA 98.7% (80/81), followed by rmpA2 (82.7%, 67/81), iroN (98.7%, 80/81), and iutA 90.1% (70/81). There was no significant difference in the distribution of virulence genes between invasive HvKP and non-invasive HvKP isolates (P>0.05).

Conclusion

Invasive HvKP infection in this study was positively associated with diabetes as independent risk factors. Antibiotic therapy combined with surgical drainage is one of the most effective treatment measures of HvKP infection. Adequate attention should be paid to HvKP infection in clinical and microbiological laboratories.

Essential Oil of Calotropis procera: Comparative Chemical Profiles, Antimicrobial Activity, and Allelopathic Potential on Weeds

Plants are considered green resources for thousands of bioactive compounds. Essential oils (EOs) are an important class of secondary compounds with various biological activities, including allelopathic and antimicrobial activities. Herein, the present study aimed to compare the chemical profiles of the EOs of the widely distributed medicinal plant Calotropis procera collected from Saudi Arabia and Egypt. In addition, this study also aimed to assess their allelopathic and antimicrobial activities. The EOs from Egyptian and Saudi ecospecies were extracted by hydrodistillation and analyzed via GC-MS. The correlation between the analyzed EOs and those published from Egypt, India, and Nigeria was assessed by principal component analysis (PCA) and agglomerative hierarchical clustering (AHC). The allelopathic activity of the extracted EOs was tested against two weeds (Bidens pilosa and Dactyloctenium aegyptium). Moreover, the EOs were tested for antimicrobial activity against seven bacterial and two fungal strains. Ninety compounds were identified from both ecospecies, where 76 compounds were recorded in Saudi ecospecies and 33 in the Egyptian one. Terpenes were recorded as the main components along with hydrocarbons, aromatics, and carotenoids. The sesquiterpenes (54.07%) were the most abundant component of EO of the Saudi sample, while the diterpenes (44.82%) represented the mains of the Egyptian one. Hinesol (13.50%), trans-chrysanthenyl acetate (12.33%), 1,4-trans-1,7-cis-acorenone (7.62%), phytol (8.73%), and myristicin (6.13%) were found as the major constituents of EO of the Saudi sample, while phytol (38.02%), n-docosane (6.86%), linoleic acid (6.36%), n-pentacosane (6.31%), and bicyclogermacrene (4.37%) represented the main compounds of the Egyptian one. It was evident that the EOs of both ecospecies had potent phytotoxic activity against the two tested weeds, while the EO of the Egyptian ecospecies was more effective, particularly on the weed D. aegyptium. Moreover, the EOs showed substantial antibacterial and antifungal activities. The present study revealed that the EOs of Egyptian and Saudi ecospecies were different in quality and quantity, which could be attributed to the variant environmental and climatic conditions. The EOs of both ecospecies showed significant allelopathic and antimicrobial activity; therefore, these EOs could be considered as potential green eco-friendly resources for weed and microbe control, considering that this plant is widely grown in arid habitats.

Antimicrobial Resistance in Escherichia coli and Resistance Genes in Coliphages from a Small Animal Clinic and in a Patient Dog with Chronic Urinary Tract Infection

Antimicrobial resistance is on the rise in certain pathogens that infect pets and their owners. This has raised concerns about the use of antibiotics and the transfer of resistance elements in small animal clinics. We sampled a surgery unit, diagnostic rooms after disinfection, and a dog with chronic urinary tract infection (UTI), in a small animal clinic in Austria, and isolated/characterized phages and Escherichia (E.) coli for antimicrobial resistance, resistance genes and transduction ability. Neither the coliphages nor E. coli were isolated in the 20 samples of the surgery units and diagnostic rooms. From the urinary tract of the dog, we recovered 57 E. coli isolates and 60 coliphages. All of the E. coli isolates were determined as resistant against nalidixic acid, 47 against ampicillin, 34 against sulfonamides, and 33 against streptomycin. No isolate held resistance against tetracycline, trimethoprim, kanamycin, or chloramphenicol. Among the 60 phages, 29 tested positive for one or more resistance gene(s) by PCR, but none was able to transduce it to a laboratory strain or to an E. coli isolated from samples. Nevertheless, six phages out of 60 were able to transduce ampicillin resistance (bla gene) after being grown on a puc19 harboring E. coli strain.

The impact that β-citronellol isomers have on the biofilm formation of Candida yeasts

Infections associated with biofilms developed by Candida spp. are becoming a great problem due to its resistance against the immune response of the host and the action of antifungal agents. Hence, finding substances that can inhibit the development of biofilms increases the likelihood that these compounds one day can become good antifungals applied in the clinic. The aim of this study was to evaluate the effect of β-citronellol enantiomers on the biofilm formation by Candida albicans and Candida tropicalis isolated from bloodstream infections. Inhibition was evaluated by reading microplates treated with different concentrations of R-(+)-β-citronellol, S-(-)-β-citronellol and amphotericin B, compared to negative control, in spectrophotometer at 590 nm. All tested concentrations of β-citronellol enantiomers inhibited the biofilm formation of Candida. However, it is still necessary to evaluate the behavior of these isomers on mature biofilms, so that they can become more viable as antifungal therapeutical agents.

Antiviral effect of Hornstedtia bella Škorničk essential oil from the whole plant against vaccinia virus (VV)

In the prevention of epidemic and pandemic emerging and neglected viral infections, natural products are an important source of lead compounds. Hornstedtia bella Škorničkis is a rhizomatous herb growing in the forest of central Vietnam. Hornstedtia bella essential oil (Hb EO) was recently characterised by our group as endowed of antimicrobial activity against Staphylococcus aureus Methicillin-Resistant strains. Here, we describe for the first time the evaluation of Hb EO against a spectrum of viruses responsible for important human diseases. Hb EO resulted active against Vaccinia virus (VV) (EC₅₀ values 80 μg/mL), closely related to variola virus, causative agent of smallpox. Hb EO was able to strongly reduce the viral VV titer in cell-based assay at not cytotoxic concentration and its potential mode of action was characterised by virucidal activity evaluation followed by time-of-addition assay. Furthermore, Hb EO antiviral activity was implemented in a combination study with the mycophenolic acid.

Synergistic Effect of Pseudolaric Acid B with Fluconazole Against Resistant Isolates and Biofilm of Candida tropicalis

Purpose

Candida tropicalis (C. tropicalis) has emerged as an important fungal pathogen due to its increasing resistance to conventional antifungal agents, especially fluconazole (FLC). Pseudolaric acid B (PAB), a herbal-originated diterpene acid from Pseudolarix kaempferi Gordon, has been reported to possess inhibitory activity against fungus. The present study aims to investigate the antifungal effect of PAB alone and in combination with FLC on planktonic and biofilm cells of C. tropicalis.

Methods

The antifungal activity of PAB against planktonic isolates was evaluated alone and in combination with FLC using the chequerboard microdilution method and growth curve assay. The anti-biofilm effects were quantified by tetrazolium (XTT) reduction assay, which were further confirmed by scanning electron microscopy (SEM) and fluorescent microscope to observe morphological changes of biofilm treated with PAB and FLC.

Results

It was revealed that PAB alone exhibited similar inhibitory activity against FLC-resistant and FLC-susceptible strains with median MIC ranging from 8 to 16 µg/mL. When administered in combination, synergism was observed in all (13/13) FLC-resistant and (2/9) FLC-susceptible strains with FICI ranging from 0.070 to 0.375. Moreover, the concomitant use of PAB and FLC exhibited a strong dose-dependent synergistic inhibitory effect on the early and mature biofilm, eliminating more than 80% biofilm formation. SEM found that PAB, different from azoles, could significantly inhibit spore germination and destroy the cell integrity causing cell deformation, swelling, collapse and outer membrane perforation.

Conclusion

PAB was highly active against FLC-resistant isolates and biofilm of C. tropicalis, particularly when combined with FLC. These findings suggest that PAB may have potential as a novel antifungal agent with different targets from azole drugs.

Phytochemical Compositions and Biological Activities of Essential Oils from the Leaves, Rhizomes and Whole Plant of Hornstedtia bella Škorničk

The rapid emergence of drug-resistant strains and novel viruses have motivated the search for new anti-infectious agents. In this study, the chemical compositions and cytotoxicity, as well as the antibacterial, antifungal, antitrichomonas, and antiviral activities of essential oils from the leaves, rhizomes, and whole plant of Hornstedtia bella were investigated. The GC/MS analysis showed that β-pinene, E-β-caryophyllene, and α-humulene were found at high concentrations in the essential oils. The essential oils exhibited (i) inhibition against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis with minimum inhibitory concentrations (MIC) and minimum lethal concentration (MLC) values from 1 to 4% (v/v); (ii) MIC and MLC values from 2 to 16% (v/v) in Candida tropicalis and Candida parapsilosis; (iii) MIC and MLC values from 4 to 16% in Enterococcus faecalis; and (iv) MIC and MLC values from 8 to greater than or equal to 16% (v/v) in the remaining strains, including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, and Candida glabrata. In antitrichomonas activity, the leaves and whole-plant oils of Hornstedtia bella possessed IC₅₀, IC₉₀, and MLC values of 0.008%, 0.016%, and 0.03% (v/v), respectively, whilst those of rhizomes oil had in turn, 0.004%, 0.008%, and 0.016% (v/v).Besides, the leaf oil showed a weak cytotoxicity against Vero 76 and MRC-5; meanwhile, rhizomes and whole-plant oils did not exert any toxic effects on cell monolayers. Finally, these oils were not active against EV-A71.

Comparison of In Vitro Antibacterial Activity of Epaltes divaricata and Vetiveria zizanioides against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital- and community-acquired infections worldwide. Therefore, this study was conducted to explore the antibacterial activity of the two medicinal plants Epaltes divaricata and Vetiveria zizanioides against strains of MRSA which were isolated from patients with skin and soft tissue infections. Hexane, ethanol, and water extracts of E. divaricata (whole plant) and V. zizanioides (roots) were prepared. Clinical isolates of MRSA strains (n = 20) were used for the study. Bacterial susceptibility was tested using a disc diffusion assay. Minimum inhibitory concentration (MIC) was determined by a broth microdilution method. Vancomycin was used as the positive control. Hexane, ethanol, and water extracts of E. divaricata showed inhibitory zones against MRSA. Except for water extract, both hexane and ethanol extracts of V. zizanioides showed inhibitory zones. MIC ranges of hexane, ethanol, and water extracts in E. divaricata were 0.012-0.32 mg/mL, 0.019-2.4 mg/mL, and 0.019-0.48 mg/mL, respectively. Respective MIC ranges of hexane and ethanol extracts of V. zizanioides were 0.003-0.032 mg/mL and 0.019-2.4 mg/mL. The hexane extract of V. zizanioides inhibited 55% of the selected MRSA strains at a relatively low MIC value of 0.012 mg/mL. The hexane extract of both plants demonstrated inhibition of 75% of MRSA strains at a MIC value of 0.064 mg/mL. Ethanol extract of V. zizanioides and E. divaricata, respectively, inhibited 70% and 45% of MRSA strains at the MIC of 0.096 mg/mL, whereas water extract of E. divaricata inhibited 80% of MRSA strains at the same MIC. Both E. divaricata and V. zizanioides were equally effective against MRSA at a MIC of 0.064 mg/mL. But V. zizanioides was more effective since the hexane extract inhibited more than 50% of MRSA strains at significantly a lower MIC value of 0.012 mg/mL. Fractionation, purification, and identification of active compounds will warrant further evaluation of the therapeutic potential of both plant extracts.