Microbial resistance: The role of efflux pump superfamilies and their respective substrates

Tackling multi-drug resistant fungi by efflux pump inhibitors

The emergence of multidrug-resistant fungi is of grave concern, and its infections are responsible for significant deaths among immunocompromised patients. The treatment of fungal infections primarily relies on a clinical class of antibiotics, including azoles, polyenes, echinocandins, polyketides, and a nucleotide analogue. However, the incidence of fungal infections is increasing as the treatment for human and plant fungal infections overlaps with antifungal drugs. The need for new antifungal agents acting on different targets than known targets is undeniable. Also, the pace at which loss of fungal susceptibility to antibiotics cannot be undermined. There are several modes by which fungi can develop resistance to antibiotics, including reduced drug uptake, drug target alteration, and a reduction in the cellular concentration of the drug due to active extrusions and biofilm formation. The efflux pump's overexpression in the fungi primarily reduced the antibiotic's concentration to a sub-lethal concentration, thus responsible for developing resistant fungus strains. Several strategies are used to check antibiotic resistance in multi-drug resistant fungi, including synthesizing antibiotic analogs and giving antibiotics in combination therapies. Among them, the efflux pump protein inhibitors are considered potential adjuvants to antibiotics and can block the efflux of antibiotics by inhibiting efflux pump protein transporters. Moreover, it can sensitize the antifungal drugs to multi-drug resistant fungi with overexpressed efflux pump proteins. This review discusses the natural lead molecules, repurposable drugs, and formulation strategies to overcome the efflux pump activity in the fungi.

Genetic basis of antibiotic resistance in bovine mastitis and its possible implications for human and ecological health

Bovine mastitis is a mammary gland inflammation that can occur due to infectious pathogens, Staphylococcus aureus and Escherichia coli, which are, respectively, the most prevalent Gram-positive and Gram-negative bacteria associated with this disease. Currently, antibiotic treatment has become more complicated due to the presence of resistant pathogens. This review, therefore, aims to identify the most common resistance genes reported for these strains in the last four years. During the review, it was noted that blaZ, blaSHV, blaTEM, and blaampC are the most reported genes for S. aureus and E. coli, associated with drug inactivation, mainly β-lactamases. They are characterized by generating bacterial resistance to β-lactam antibiotics, the most common treatment in animal and human bacterial treatments (penicillins and cephalosporins, among others). Genes associated with efflux systems were also present in the two strains and included norA, tetA, tetC, and tetK, which generate resistance to macrolide and tetracycline antibiotics. Additionally, the effects of spreading resistance between animals and humans through direct contact (such as consumption of contaminated milk) or indirect contact (through environmental contamination) has been deeply discussed, emphasizing the importance of having adequate sanitation and antibiotic control and administration protocols.

Computational evaluation of efflux pump homologues and lignans as potent inhibitors against multidrug-resistant Salmonella typhi

Typhoid fever, caused by Salmonella enterica serovar typhi, presents a substantial global health threat, particularly in regions with limited healthcare infrastructure. The rise of multidrug-resistant strains of S. typhi exacerbates this challenge, severely compromising conventional treatment efficacy due to over activity of efflux pumps. In our study, a comprehensive exploration of two fundamental aspects to combat MDR in S. typhi is carried out; i.e. employing advanced bioinformatics analyses and AlphaFold AI, We successfully identified and characterised a putative homologue, ABC-TPA, reminiscent of the P-glycoprotein (P-gp) known for its role in multidrug resistance in diverse pathogens. This discovery provides a critical foundation for understanding the potential mechanisms driving antibiotic resistance in S. typhi. Furthermore, employing computational methodologies, We meticulously assessed the potential of lignans, specifically Schisandrin A, B, and C, as promising Efflux Pump Inhibitors (EPIs) against the identified P-gp homologue in S. typhi. Noteworthy findings revealed robust binding interactions of Schisandrin A and B with the target protein, indicating substantial inhibitory capabilities. In contrast, Schisandrin C exhibited instability, showing varied effectiveness among the evaluated lignans. Pharmacokinetics and toxicity predictions underscored the favourable attributes of Schisandrin A, including prolonged action duration. Furthermore, high systemic stability and demanished toxicity profile of SA and SB present their therapeutic efficacy against MDR. This comprehensive investigation not only elucidates potential therapeutic strategies against MDR strains of S. typhi but also highlights the relevance of computational approaches in identifying and evaluating promising candidates. These findings lay a robust foundation for future empirical studies to address the formidable challenges antibiotic resistance poses in this clinically significant infectious diseases.

Orange passion fruit (Passiflora caerulea L.) as a new raw material for acetic fermentation: evaluation of organic acids and phenolic profile, in vitro digestion, and biological activities

BACKGROUND

This study evaluated for the first time the potential of orange passion fruit as a base for alcoholic and acetic fermentations, with a view to assessing its profile of organic acids and polyphenols, in vitro digestion, and biological activities.

RESULTS

In terms of aliphatic organic acids, malic acid was the majority in the wine (3.19 g L-1), while in the vinegar, it was acetic acid (46.84 g L-1). 3,4-Dihydroxybenzoic acid (3,4-DHB) was the major phenolic compound in the wine and vinegar samples (3443.93 and 2980.00 μg L-1, respectively). After the in vitro gastrointestinal simulation stage, the wine showed high bioaccessibility for the compounds sinipaldehyde (82.97%) and 2,4-dihydroxybenzoic acid (2,4-DHBA, 81.27%), while the vinegar exhibited high bioaccessibility for sinipaldehyde (89.39%). Through multivariate analysis, it was observed that 3,4-DHB was highly concentrated in the different digested fractions obtained from the wine. In contrast, in the vinegar, the stability of isorahmenetin and Quercetin 3-o-rhamnoside was observed during the in vitro digestion simulation. Lastly, the vinegar stood out for its inhibition rates of α-amylase (23.93%), α-glucoside (18.34%), and angiotensin-converting enzyme (10.92%). In addition, the vinegar had an inhibitory effect on the pathogenic microorganisms Salmonella enteritidis, Escherichia coli, and Listeria monocytogenes.

CONCLUSION

Orange passion fruit has proved to be a promising raw material for the development of fermented beverages. Therefore, this study provides an unprecedented perspective on the use and valorization of orange passion fruit, contributing significantly to the advancement of knowledge about fermented products and the associated nutritional and functional possibilities. © 2024 Society of Chemical Industry.

An Integrated Pipeline and Overexpression of a Novel Efflux Transporter, YoeA, Significantly Increases Plipastatin Production in Bacillus subtilis

Plipastatin, an antimicrobial peptide produced by Bacillus subtilis, exhibits remarkable antimicrobial activity against a diverse range of pathogenic bacteria and fungi. However, the practical application of plipastatin has been significantly hampered by its low yield in wild Bacillus species. Here, the native promoters of both the plipastatin operon and the sfp gene in the mono-producing strain M-24 were replaced by the constitutive promoter P43, resulting in plipastatin titers being increased by 27% (607 mg/mL) and 50% (717 mg/mL), respectively. Overexpression of long chain fatty acid coenzyme A ligase (LCFA) increased the yield of plipastatin by 105% (980 mg/mL). A new efflux transporter, YoeA, was identified as a MATE (multidrug and toxic compound extrusion) family member, overexpression of yoeA enhanced plipastatin production to 1233 mg/mL, an increase of 157%, and knockout of yoeA decreased plipastatin production by 70%; in contrast, overexpression or knockout of yoeA in mono-producing surfactin and iturin engineered strains only slightly affected their production, demonstrating that YoeA acts as the major exporter for plipastatin. Co-overexpression of lcfA and yoeA improved plipastatin production to 1890 mg/mL, which was further elevated to 2060 mg/mL after abrB gene deletion. Lastly, the use of optimized culture medium achieved 2514 mg/mL plipastatin production, which was 5.26-fold higher than that of the initial strain. These results suggest that multiple strain engineering is an effective strategy for increasing lipopeptide production, and identification of the novel transport efflux protein YoeA provides new insights into the regulation and industrial application of plipastatin.

Modulators of Candida albicans Membrane Drug Transporters: A Lucrative Portfolio for the Development of Effective Antifungals

The escalating prevalence of membrane drug transporters and drug efflux pumps in pathogenic yeast like Candida albicans necessitates a comprehensive understanding of their roles in MDR. The overexpression of drug transporter families, ABC and MFS, implicated in MDR through drug efflux and poses a significant challenge in the diagnosis and treatment of fungal infection. Various mechanisms have been proposed for MDR; however, the upregulation of ABC and MFS superfamily transporters is most noticeable in MDR. The direct inhibition of these transporters seems an efficient strategy to overcome this problem. The goal of the article is to present an overview of the prospect of utilizing these modulators of C. albicans drug transports as effective antifungal molecules against MDR addressing a critical gap in the field. The review tries to address to prevent drug extrusion by modulating the expression of drug transporters of C. albicans. The review discussed the progress in identifying potent, selective, and non-toxic modulators of these transporters to develop some effective antifungals and overcome MDR. We reviewed major studies in this area and found that recent work has shifted toward the exploration of natural compounds as potential modulators to restore drug sensitivity in MDR fungal cells. The focus of this review is to survey and interpret current research information on modulators of C. albicans drug transporters from natural sources emphasizing those compounds that are potent antifungal agents.

Efflux Pump Inhibition-Based Screening and Anti-Infective Evaluation of Punica granatum Against Bacterial Pathogens

Drug efflux pumps contribute to bacterial multidrug resistance (MDR), reducing antibiotic effectiveness and causing treatment failures. Besides their role in MDR, efflux pumps also assist in the transportation of quorum sensing (QS) signal molecules and increased the tolerance of biofilms. Recently, the search for efflux pump inhibitors from natural sources, including anti-infective plants, has gained attention as a potential therapy against drug-resistant bacteria. In this study, 19 traditional Indian medicinal plants were screened for their efflux pump inhibitory activity against Escherichia coli TGI. The promising extract, i.e., Punica granatum was subsequently fractioned in the solvents of increasing polarity. Among them, at sub-MIC active EPI fraction was PGEF (P. granatum ethyl acetate fraction), further investigated for anti-infective potential against Chromobacterium violaceum 12,472, Pseudomonas aeruginosa PAO1, and Serratia marcescens MTCC 97. PGEF was also evaluated for in vivo efficacy in Caenorhabditis elegans model. Major phytocompounds were analyzed by mass spectroscopic techniques. At respective Sub-MIC, PGEF reduced violacein production by 71.14% in C. violaceum 12,472. Moreover, PGEF inhibited pyocyanin (64.72%), pyoverdine (48.17%), protease (51.35%), and swarming motility (44.82%) of P. aeruginosa PAO1. Furthermore, PGEF reduced the production of prodigiosin and exoprotease by 64.73% and 61.80%, respectively. Similarly, at sub-MIC, PGEF inhibited (≥ 50%) biofilm development in all test pathogens. The key phytocompounds detected in active fraction include 5-hydroxymethylfurfural, trans-p-coumaric acid 4- glucoside, (-)-Epicatechin 3'-O-glucuronide, and ellagic acid. Interestingly, PGEF also demonstrated anti-infective efficacy against the PAO1-infected C. elegans test model and highlighting its therapeutic potential as an anti-infective agent to combat drug-resistant problems.

Evaluation of Antimicrobial Activity of Kitaibelia vitifolia Extract against Proven Antibiotic-Susceptible and Multidrug-Resistant (MDR) Strains of Bacteria of Clinical Origin

The goal of the present research was to screen the antimicrobial activity of an ethanolic extract of Kitaibelia vitifolia against 30 multidrug-resistant (MDR) bacterial strains isolated from healthcare-associated infections. Minimum inhibitory concentrations (MICs) of the samples against the tested bacteria were determined using the microdilution method. MDR bacterial strains were characterized using standard biochemical tests and the commercial identification systems API 20 NE and API 20 E as: Klebsiella spp. (18 isolates-I); methicillin-resistant Staphylococcus aureus (MRSA)-3; Acinetobacter spp.-3; Pseudomonas aeruginosa-5; vancomycin-resistant Enterococcus (VRE)-1. The sensitivity of isolated bacterial strains was determined using the disc diffusion method against 25 commonly used antibiotics. The highest level of sensitivity to K. vitifolia extract was confirmed in 88.89% of Klebsiella spp. isolates, E. coli ATCC 25922, two strains of MRSA (1726, 1063), Acinetobacter spp. strain 1578, and VRE strain 30, like Enterococcus faecalis ATCC 29212 (MIC =< 2.44 μg/mL). The lowest sensitivity was exhibited by 75.00% of Acinetobacter spp. (strains 1577 and 6401), where the highest values for MICs were noted (1250 μg/mL). The results indicate that the extract of K. vitifolia could be a possible source for creating new, efficient, and effective natural medicines for combat against MDR strains of bacteria.

Sterilizing orthodontic appliances: A systematic review and meta-analysis on the available methods

Infection control is essential to protect both the doctor and the patient by preventing the spread of infectious diseases. There is no exception in the field of dentistry, particularly in orthodontics, where numerous appliances are used for a variety of functions and also because the mouth cavity has the highest concentration of bacteria of any body part. Through this systematic review, we aimed to assess the various methods of sterilization employed in an orthodontic setting. Using relevant keywords, reference searches, and citation searches, the databases such as PubMed, MEDLINE, Web of Science, Cochrane, and Scopus were all searched; a total of 206 documents were found, of which 113 were initially selected. The remaining 23 distinct papers were initially made available after 90 publications that were identical to or similar to one another were eliminated. The final selection was made from eight documents that met all inclusion and exclusion requirements. The existing methods of sterilization were found to be competent in dealing with the microorganisms found in a typical orthodontic setting. The chemical method of sterilization was the norm in most of the studies that we assessed, with glutaraldehyde and peracetic acid (PAA) being the most commonly employed compounds for disinfection. PROSPERO Registration Number: CRD42022380831.

Antibiotic-Potentiating Activity of the Schinus terebinthifolius Raddi Essential Oil against MDR Bacterial Strains

Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus are the primary bacteria that cause clinical infections, such as urinary and intestinal infections, pneumonia, endocarditis, and sepsis. Bacterial resistance is an innate natural occurrence in microorganisms, resulting from mutations or the lateral exchange of genetic material. This serves as evidence for the association between drug consumption and pathogen resistance. Evidence has demonstrated that the association between conventional antibiotics and natural products is a promising pharmacological strategy to overcome resistance mechanisms. Considering the large body of research demonstrating the significant antimicrobial activities of Schinus terebinthifolius Raddi, the present study aimed to evaluate the chemical composition and antibiotic-enhancing effects of Schinus terebinthifolius Raddi essential oil (STEO) against the standard and multidrug-resistant strains of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The STEO was extracted by hydrodistillation using a Clevenger-type vacuum rotary evaporator. The Minimum Inhibitory Concentration (MIC) of the STEO was assessed by the microdilution method to evaluate the antibacterial activity. The antibiotic-enhancing activity of the essential oil was assessed by determining the MIC of antibiotics in the presence of a sub-inhibitory concentration (MIC/8) of the natural product. The GC-MS analysis revealed alpha-pinene (24.3%), gamma-muurolene (16.6%), and myrcene (13.7%) as major constituents of the STEO. The STEO potentiated the enhanced antibacterial activity of norfloxacin and gentamicin against all the strains and increased the action of penicillin against the Gram-negative strains. Therefore, it is concluded that although the STEO does not exhibit clinically effective antibacterial activity, its association with conventional antibiotics results in enhanced antibiotic activity.

Persistence of Salmonella Typhimurium and antibiotic resistance genes in different types of soil influenced by flooding and soil properties

Salmonella is a zoonotic foodborne bacterial pathogen that can seriously harm health. Persistence of Salmonella and antibiotic resistance genes (ARGs) in different types of soil under flooding and natural conditions are rare explored. This study investigated the dynamic changes of the Salmonella, ARGs and bacterial communities in three types of soils applied with pig manure in lab scale. Abundance of the Salmonella Typhimurium in soils reduced to the detection limit varied from 40 to 180 days, most of the Salmonella did not survive in soil for more than 90 days. Flooding and soil texture (content of sand) promote the decline rate of Salmonella. No Salmonella was found have acquired resistance gene from the soil or manure after 90 days. 64 ARGs and 11 MGEs were quantified, abundance of these genes and risky ARGs both gradually decline along with the extension of time. Most of the extrinsic ARGs cannot colonize in soil, cellular protection and antibiotic deactivation were their main resistance mechanism. Multidrug resistance and efflux pump were the dominant class and mechanism of soil intrinsic ARGs. Flooding can affect the ARGs profiles by reducing the types of extrinsic ARGs invaded into soil and inhibit the proliferation of intrinsic genes. Soil sand content, soil moisture and nutrition concentrations had significant direct effect on the abundance or profile of ARGs. Soil bacterial community structures also changed along with the extension of time and affected by flooding. Network analyses between ARGs and bacteria taxa revealed that Actinobacteria and Myxococcia were the main hosts of intrinsic ARGs, some taxa may play a role in inhibiting extrinsic ARGs colonization in the soils. These findings unveil that saturate soil with water may play a positive role in reducing potential risk of Salmonella and ARGs in the farmland environment.

Microbial resistance to sanitizers in the food industry: review

Hygiene programs which comprise the cleaning and sanitization steps are part of the Good Hygiene Practices (GHP) and are considered essential to ensure food safety and quality. Inadequate hygiene practices may contribute to the occurrence of foodborne diseases, development of microbial resistance to sanitizers, and economic losses. In general, the sanitizer resistance is classified as intrinsic or acquired. The former is an inherent characteristic, naturally present in some microorganisms, whereas the latter is linked to genetic modifications that can occur at random or after continuous exposure to a nonnormal condition. The resistance mechanisms can involve changes in membrane permeability or in the efflux pump, and enzymatic activity. The efflux pump mechanism is the most elucidated in relation to the resistance caused by the use of different types of sanitizers. In addition, microbial resistance to sanitizers can also be favored in the presence of biofilms due to the protection given by the glycocalyx matrix and genetic changes. Therefore, this review aimed to show the main microbial resistance mechanisms to sanitizers, including genetic modifications, biofilm formation, and permeability barrier.