Antibiotic resistance in bacteria - an emerging public health problem

Determining the effect of a new truncated CecropinA-Magenin2 (CE-MA) hybrid peptide on the expression of multidrug-resistant (MDR) Mycobacterium tuberculosis efflux genes

A significant issue in treating bacterial infections is multidrug resistance (MDR) microbes. Drug efflux pumps that reduce cellular drug accumulation are frequently linked to drug resistance. In this study, we set out to determine the effects of CE-MA truncated peptide derivatives against MDR Mycobacterium tuberculosis. Following the assessment of the minimum inhibitory concentrations (MICs) of these peptides against MDR Mycobacterium tuberculosis, a Real-Time PCR was used to examine the expression of six drug efflux pump genes. Next, an MTT assay was performed to test the cytotoxicity of peptides against the A549 cell line. The outcomes demonstrated that CE-MA significantly upregulated gene expression of mmr, and Rv0876c (⩾ 4-fold) than untreated bacteria. Also, under CMt2 stress, significant overexpression of Rv0876c and drrA was seen. However, the results show that upregulation in CMt2-treated bacteria in comparison CE-MA treated bacteria is significantly less for genes tap (P < 0.05), mmr (P < 0.0001), and Rv0876c (P < 0.001). Meanwhile, CMt1 only upregulated the Rv0876c gene and downregulated gene expression of tap, drrA, and mmr. It was also found that all three peptides have no significant effect (P > 0.05) on changing the expression of genes drrC and pstB. Less than 10% of the A549 cell line was susceptible to the toxicity of CMt1 and CMt2 at their MICs range. Our results emphasize the significance of investigating novel peptide-based approaches to combat MDR Mycobacterium tuberculosis and point to these peptides as prospective candidates for additional research.

Investigating the Therapeutic Ability of Novel Antimicrobial Peptide Dendropsophin 1 and Its Analogues through Membrane Disruption and Monomeric Pore Formation

Antimicrobial peptides (AMPs) are an alternative source of antibiotics that fight worldwide antibiotic-resistant catastrophes. Dendropsophin 1 (Dc1) is a recently invented novel AMP with 17 amino acid residues obtained from the screen secretion of a frog named Dendropsophus columbianus. Dc1 has two slightly mutated analogues, namely, Dc1.1 and Dc1.2, with improved cationicity and mean amphipathic moment to enhance the selective toxicity against microorganisms. Experimental results indicate that Dc1 and Dc1.1 have similar antimicrobial activity against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus, whereas the synthesized peptide Dc1.2 has shown antimicrobial activity against a wide range of microorganisms. However, the molecular level details of the peptide-membrane interaction and the corresponding changes in the peptide structure remain elusive. In this study, we investigate the bacterial membrane disruption capability of these AMPs by running a total of 14.2 μs long molecular dynamics (MD) simulations. Our findings suggest that all three peptides affect the upper layer of the membrane with different degrees of disruption. After penetration, Dc1 and Dc1.2 retain stable α-helices in the core region, indicating the potential to disrupt the second layer. However, secondary structure analysis shows that Dc1.2 attains extended helical regions on the C-terminus, suggesting it as the superior candidate among the analogues to have the potential of stable pore formation, leading to bacterial cell death. To speed up our study, we adopt a one-transmembrane configuration of Dc1, Dc1.1, and Dc1.2 and find toroidal pores with subsequent water leakage for Dc1.2.

Prevalence of antibiotic self-medication and knowledge of antimicrobial resistance among community members in Neno District rural Malawi: A cross-sectional study

Objectives

Despite global efforts to address antibiotic self-medication, it is still significantly prevalent. This study aimed to investigate the prevalence of antibiotic self-medication and assess knowledge of antibiotic resistance among community members in Neno District, rural Malawi.

Methods

A cross-sectional, community-based study was conducted from September to November 2023, using simple random sampling across 169 villages. Participants from two households per village were surveyed using a "drug bag" method, focusing on those who had taken antibiotics within the preceding 6 months. In addition, drug retailers were selected via snowball sampling for interviews.

Results

Of the 531 participants and 39 drug retailers, 71.1% reported antibiotic use, with 69.5% self-medicating in the past 6 months, with convenience (31.5%) and confidence (26.7%) being the reasons. Common symptoms prompting self-medication included cough (29.9%), sore throat (28.6%), and aches and pain (28.6%). Amoxicillin (61.1%) and cotrimoxazole (29.6%) were the most used antibiotics. More than half (53.1%) reused leftover antibiotics from health facilities, with employed participants significantly more likely to self-medicate. Awareness of antibiotic resistance was low (16.1%), mainly learned from hospitals. Unlawful antibiotic sales by drug retailers (46.2%) were noted.

Conclusions

The study highlights the urgent need for government-led efforts to regulate antibiotic use and increase public awareness to mitigate the impact on public health.

Photocatalytic degradation of antibiotics and antimicrobial and anticancer activities of two-dimensional ZnO nanosheets

Active pharmaceutical ingredients have emerged as an environmentally undesirable element because of their widespread exploitation and consequent pollution, which has deleterious effects on living things. In the pursuit of sustainable environmental remediation, biomedical applications, and energy production, there has been a significant focus on two-dimensional materials (2D materials) owing to their unique electrical, optical, and structural properties. Herein, we have synthesized 2D zinc oxide nanosheets (ZnO NSs) using a facile and practicable hydrothermal method and characterized them thoroughly using spectroscopic and microscopic techniques. The 2D nanosheets are used as an efficient photocatalyst for antibiotic (herein, end-user ciprofloxacin (CIP) was used as a model antibiotic) degradation under sunlight. It is observed that ZnO NSs photodegrade ~ 90% of CIP within two hours of sunlight illumination. The molecular mechanism of CIP degradation is proposed based on ex-situ IR analysis. Moreover, the 2D ZNO NSs are used as an antimicrobial agent and exhibit antibacterial qualities against a range of bacterial species, including Escherichia coli, Staphylococcus aureus, and MIC of the bacteria are found to be 5 μg/l and 10 μg/l, respectively. Despite having the biocompatible nature of ZnO, as-synthesized nanosheets have also shown cytotoxicity against two types of cancer cells, i.e. A549 and A375. Thus, ZnO nanosheets showed a nontoxic nature, which can be exploited as promising alternatives in different biomedical applications.

Evaluation of Antibacterial Activity of Madhuca longifolia (Mahua) Stem Extract Against Streptococcus mutans: An In Vitro Study

Introduction Madhuca longifolia is one of the important folklore medicinal plants with a plethora of established pharmaceutical properties. Its twigs are used as chewing sticks (toothbrushes), and it is believed that if a person uses it daily, it will make their gum healthy and strong. No study has ever been conducted to evaluate the antibacterial effect of M. longifolia extracts against oral microorganisms. Materials and methods Fresh stem twigs (Madkam Kaarkad) of M. longifolia were collected and dried. The dried stem was cut into small pieces, 5 g of which was mixed with 50 ml distilled water (in the ratio 1:10) and kept for two days for maceration. After two days, the liquid was filtered and the final filtrate was obtained, from which dry pellets were made and stored in the refrigerator at 4°C. Brain heart infusion agar was used as a medium to grow the lyophilized bacteria. Pure strains of Streptococcus mutans 890 were obtained from the Microbial Type Culture Collection (MTCC) and MTCC-suggested protocol was followed for the revival of lyophilized bacteria. The agar well diffusion method was used to determine the zone of inhibition. The extract of stems with different concentrations (10%, 7.5%, 5.0%, and 2.5%) and at different volumes (100 µl, 150 µl, 200 µl, and 250 µl) was transferred to the agar plates. Chlorhexidine 0.2% was used as a control and it was also transferred to agar plates, which were incubated aerobically at 37°C for 24 hours. Antibacterial activity was interpreted from the size of the diameter of zones of inhibition measured in millimeters using a measuring scale in all the agar plates. Results The minimum zone of inhibition of 11 mm at 2.5% concentration and 100 µl volume of M. longifolia extract and the maximum zone of inhibition of 20 mm at 10% concentration and 250 µl volume was notified. While for chlorhexidine at 0.2% concentration, the zone of inhibition obtained was 9.5 mm at 40 µl volume. The minimum inhibitory concentration (MIC) value of M. longifolia was found to be 35 mg/ml. Conclusion M. longifolia showed marked antibacterial activity against S. mutans and has a high MIC value. Therefore, this plant can be considered an effective agent against oral diseases like dental caries.

Molecular responses during bacterial filamentation reveal inhibition methods of drug-resistant bacteria

Bacterial antimicrobial resistance (AMR) is among the most significant challenges to current human society. Exposing bacteria to antibiotics can activate their self-saving responses, e.g., filamentation, leading to the development of bacterial AMR. Understanding the molecular changes during the self-saving responses can reveal new inhibition methods of drug-resistant bacteria. Herein, we used an online microfluidics mass spectrometry system for real-time characterization of metabolic changes of bacteria during filamentation under the stimulus of antibiotics. Significant pathways, e.g., nucleotide metabolism and coenzyme A biosynthesis, correlated to the filamentation of extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E. coli) were identified. A cyclic dinucleotide, c-di-GMP, which is derived from nucleotide metabolism and reported closely related to bacterial resistance and tolerance, was observed significantly up-regulated during the bacterial filamentation. By using a chemical inhibitor, ebselen, to inhibit diguanylate cyclases which catalyzes the synthesis of c-di-GMP, the minimum inhibitory concentration of ceftriaxone against ESBL-E. coli was significantly decreased. This inhibitory effect was also verified with other ESBL-E. coli strains and other beta-lactam antibiotics, i.e., ampicillin. A mutant strain of ESBL-E. coli by knocking out the dgcM gene was used to demonstrate that the inhibition of the antibiotic resistance to beta-lactams by ebselen was mediated through the inhibition of the diguanylate cyclase DgcM and the modulation of c-di-GMP levels. Our study uncovers the molecular changes during bacterial filamentation and proposes a method to inhibit antibiotic-resistant bacteria by combining traditional antibiotics and chemical inhibitors against the enzymes involved in bacterial self-saving responses.

Biosynthesis of Co3O4 nanomedicine by using Mollugo oppositifolia L. aqueous leaf extract and its antimicrobial, mosquito larvicidal activities

Nanotechnology is a relatively revolutionary area that generates day-to-day advancement. It makes a significant impact on our daily life. For example, in parasitology, catalysis and cosmetics, nanoparticles possess distinctive possessions that make it possible for them in a broad range of areas. We utilized Mollugo oppositifolia L. aqueous leaf extract assisted chemical reduction method to synthesize Co₃O₄ nanoparticles. Biosynthesized Co₃O₄ Nps were confirmed via UV-Vis spectroscopy, scanning electron microscope, X-ray diffraction, EDX, Fourier-transform infrared, and HR-TEM analysis. The crystallite size from XRD studies revealed around 22.7 nm. The biosynthesized Co₃O₄ nanoparticle was further assessed for mosquito larvicidal activity against south-urban mosquito larvae Culex quinquefasciatus, and antimicrobial activities. The synthesized Co₃O₄ particle (2) displayed significant larvicidal activity towards mosquito larvae Culex quinquefasciatus with the LD₅₀ value of 34.96 µg/mL than aqueous plant extract (1) and control Permethrin with the LD₅₀ value of 82.41 and 72.44 µg/mL. When compared to the standard antibacterial treatment, Ciprofloxacin, the Co₃O₄ nanoparticle (2) produced demonstrates significantly enhanced antibacterial action against the pathogens E. coli and B. cereus. The MIC for Co₃O₄ nanoparticles 2 against C. albicans was under 1 μg/mL, which was much lower than the MIC for the control drug, clotrimale, which was 2 µg per milliliter. Co₃O₄ nanoparticles 2, with a MIC of 2 μg/mL, has much higher antifungal activity than clotrimale, whose MIC is 4 μg/mL, against M. audouinii.

Antibiotic-Loaded Smart Platelet: A Highly Effective Invisible Mode of Killing Both Antibiotic-Sensitive and -Resistant Bacteria

Microbial pathogenesis is considered one of the most critical health challenges worldwide. Although several antibiotics have been procured and used, the microbes often manage to escape and become resistant to antibiotics. Thus, the discovery of new antibiotics and designing smart approaches toward their delivery are of great importance. In many cases, the delivery agents using foreign chemicals like lipids or polymers induce immunogenic responses of varying degrees and are limited to a shorter circulatory time and burst release. In the current work, we have designed a novel antibiotic delivery system where the antibiotic is encapsulated into a blood component-platelet. Platelets have been previously reported as efficient drug delivery vehicles for targeting cancer cells. On the other hand, during platelet-bacterial interaction, platelets can act as covercytes. Keeping this in mind, smart antibiotic-loaded platelets have been used for killing bacterial cells. The loading of the antibiotic was done using its typical nature of engulfing surrounding small molecules. The water-soluble antibiotics were loaded directly into the platelet, whereas the hydrophobic antibiotics were preloaded in polycaprolactone (FDA-approved polymer)-based nanovesicles to make them solubilized prior to loading inside the platelets. The antibiotic-loaded platelets (containing hydrophilic antibiotics or hydrophobic antibiotic -encapsulated polymer nanoparticles) were found to be stable when studied through platelet aggregometry. The carrier showed bactericidal effects at a significantly lower concentration at which the free antibiotic has negligible efficacy. This could be attributed to the molecular confinement of the antibiotics inside the platelets, therefore causing localization of the drug and leading to efficient activity against bacteria. Interestingly, the smart antibiotic-loaded platelets were capable of killing the resistant strains too at the same lower concentration regime. Therefore, the antibiotic-loaded platelet could emerge as a potential strategy for efficient delivery of antibiotics with a significant reduction of the dose required to achieve the intended antibacterial efficacy. Moreover, this antibiotic delivery method can be very useful to minimize immunogenic responses due to antibiotic administration and to avoid the development of drug resistance due to the invisible mode of delivery.

In-Vitro Catalytic and Antibacterial Potential of Green Synthesized CuO Nanoparticles against Prevalent Multiple Drug Resistant Bovine Mastitogen Staphylococcus aureus

Nanoparticles prepared from bio-reduction agents are of keen interest to researchers around the globe due to their ability to mitigate the harmful effects of chemicals. In this regard, the present study aims to synthesize copper oxide nanoparticles (CuO NPs) by utilizing root extracts of ginger and garlic as reducing agents, followed by the characterization and evaluation of their antimicrobial properties against multiple drug resistant (MDR) S. aureus. In this study, UV-vis spectroscopy revealed a reduced degree of absorption with an increase in the extract amount present in CuO. The maximum absorbance for doped NPs was recorded around 250 nm accompanying redshift. X-ray diffraction analysis revealed the monoclinic crystal phase of the particles. The fabricated NPs exhibited spherical shapes with dense agglomeration when examined with FE-SEM and TEM. The crystallite size measured by using XRD was found to be within a range of 23.38-46.64 nm for ginger-doped CuO and 26-56 nm for garlic-doped CuO. Green synthesized NPs of ginger demonstrated higher bactericidal tendencies against MDR S. aureus. At minimum and maximum concentrations of ginger-doped CuO NPs, substantial inhibition areas for MDR S. aureus were (2.05-3.80 mm) and (3.15-5.65 mm), and they were measured as (1.1-3.55 mm) and (1.25-4.45 mm) for garlic-doped NPs. Conventionally available CuO and crude aqueous extract (CAE) of ginger and garlic roots reduced MB in 12, 21, and 38 min, respectively, in comparison with an efficient (100%) reduction of dye in 1 min and 15 s for ginger and garlic doped CuO NPs.

The Pathways to Create Containers for Bacteriophage Delivery

Antimicrobial resistance is a global public health threat. One of the possible ways to solve this problem is phage therapy, but the instability of bacteriophages hinders the development of this approach. A bacteriophage delivery system that stabilizes the phage is one of the possible solutions to this problem. This study is dedicated to exploring methods to create encapsulated forms of bacteriophages for delivery. We studied the effect of proteolytic enzymes on the destruction of the polyelectrolyte microcapsule shell and revealed that protease from Streptomyces griseus was able to destroy the membrane of the microcapsule (dextran sulfate/polyarginine)3 ((DS/PArg)3). In addition, the protease decreased the activity of the bacteriophage in the second hour of incubation, and the phage lost activity after 16 h. It was found that a medium with pH 9.02 did not affect the survival of the bacteriophage or E. coli. The bacteriophages were encapsulated into polyelectrolyte microcapsules (DS/PArg)3. It was established that it is impossible to use microcapsules as a means of delivering bacteriophages since the bacteriophages are inactivated. When bacteriophages were included inside a CaCO3 core, it was demonstrated that the phage retained activity before and after the dissolution of the CaCO3 particle. From the results of this study, we recommend using CaCO3 microparticles as a container for bacteriophage delivery through the acidic stomach barrier.

Toward efficient dye degradation and the bactericidal behavior of Mo-doped La2O3 nanostructures

In this study, different concentrations (0, 0.02, 0.04, and 0.06 wt%) of Mo doped onto La2O3 nanostructures were synthesized using a one-pot co-precipitation process. The aim was to study the ability of Mo-doped La2O3 samples to degrade toxic methylene blue dye in different pH media. The bactericidal potential of synthesized samples was also investigated. The structural properties of prepared samples were examined by XRD. The observed XRD spectrum of La2O3 showed a cubic and hexagonal structure, while no change was recorded in Mo-doped La2O3 samples. Doping with Mo improved the crystallinity of the samples. UV-Vis spectrophotometry and density functional theory calculations were used to assess the optical characteristics of Mo-La2O3. The band gap energy was reduced while the absorption spectra showed prominent peaks due to Mo doping. The HR-TEM results revealed the rod-like morphology of La2O3. The rod-like network appeared to become dense upon doping. A significant degradation of MB was confirmed with Mo; furthermore, the bactericidal activities against S. aureus and E. coli were measured as 5.05 mm and 5.45 mm inhibition zones, respectively, after doping with a high concentration (6%) of Mo.

Green synthesis of silver nanoparticles with algae and the importance of capping agents in the process

BACKGROUND

Nanoparticle synthesis is a very interesting area of research currently due to the wide applications of nanoparticles. The nanoparticles have a diameter ranging between 1 and 100 nm and they are used in different fields like electronics, pharmaceuticals, cosmetics, biotechnology, medicines, etc. Nanoparticles have gained the interest of researchers due to their large surface-to-volume ratio and their capability to interact effectively with other particles. Several different methods can be used for the production of silver nanoparticles (AgNPs) including chemical, physical, and biological. Out of all the methods, the biological method is considered the cleanest and safest as no toxic chemicals are used in the process. The biological method includes the use of bacteria, fungi, algae, and plant extract for the synthesis. Algal synthesis of AgNPs is especially interesting because of the high capacity of the algae to take in metals and reduce metal ions. Algae is a widely distributed organism and its availability is abundant; an added advantage is their growth under laboratory conditions. These organisms can help in large-scale production at a low cost.

SHORT CONCLUSION

This review article explains the different factors that should be considered for the effective synthesis of AgNPs using algae. Capping agents also affect the stability of nanoparticles. It also sheds light on the importance of capping agents in the synthesis of AgNPs. Alga-mediated synthesis of AgNPs along with the use of different capping agents can help in modulating the stability and size of the nanoparticles, thereby improving its cost-effectiveness and environment-friendly production.

The Influence of Polyanions and Polycations on Bacteriophage Activity

Phage therapy is a great alternative to antibiotic drugs, but it can't effectively overcome the over-acidic medium of the stomach. We offer the use of polyelectrolyte microcapsules as a protective means of bacteriophage. It is necessary to understand the influence of polyelectrolytes on bacteriophage survival. The work studied the effect of polyanions and polycations on the coliprotetic bacteriophage's viability. We have shown that polyallylamine decreased bacteriophage's viability during increasing polyelectrolyte concentration and polyarginine had a lower inhibitory effect (then PAH) on the activity of the bacteriophage due to polyelectrolyte concentration from 0.05 to 5 mg/mL. It was shown that the inhibition of the bacteriophage by polyallylamine had an electrostatic nature and the use of high ionic strength prevented the formation of the PAH-protein capsid complex. Polystyrene sulfonate does not affect bacteriophage viability during increasing polyelectrolyte concentration from 0.05 mg/mL to 1 mg/mL. Polystyrene sulfonate decreases the viability of bacteriophage from 5 mg/mL of polyelectrolyte concentration. Dextran sulfate inhibits bacteriophage activity at 20-30%. Dextran inhibits bacteriophage activity by 80% at diapason concentration from 0.05 to 5 mg/mL and loses the inhibition effect from a concentration of 5 mg/mL.

Bacteriophages and the One Health Approach to Combat Multidrug Resistance: Is This the Way?

Antimicrobial resistance necessitates action to reduce and eliminate infectious disease, ensure animal and human health, and combat emerging diseases. Species such as Acinetobacter baumanniii, vancomycin resistant Enterococcus, methicillin resistance Staphylococcus aureus, and Pseudomonas aeruginosa, as well as other WHO priority pathogens, are becoming extremely difficult to treat. In 2017, the EU adopted the “One Health” approach to combat antibiotic resistance in animal and human medicine and to prevent the transmission of zoonotic disease. As the current therapeutic agents become increasingly inadequate, there is a dire need to establish novel methods of treatment under this One Health Framework. Bacteriophages (phages), viruses infecting bacterial species, demonstrate clear antimicrobial activity against an array of resistant species, with high levels of specificity and potency. Bacteriophages play key roles in bacterial evolution and are essential components of all ecosystems, including the human microbiome. Factors such are their specificity, potency, biocompatibility, and bactericidal activity make them desirable options as therapeutics. Issues remain, however, relating to their large-scale production, formulation, stability, and bacterial resistance, limiting their implementation globally. Phages used in therapy must be virulent, purified, and well characterized before administration. Clinical studies are warranted to assess the in vivo pharmacokinetics and pharmacodynamic characteristics of phages to fully establish their therapeutic potential.

Antibiotic prescription patterns for treating dental infections in children among general and pediatric dentists in teaching institutions of Karachi, Pakistan

BACKGROUND

Antibiotics are regularly prescribed by dental professionals in their practice, for the purpose of dental treatment as well as for the prevention of infection. The inappropriate use of antibiotics is a significant factor in the rise of antibiotic resistance. There is an immediate need for the advancement of prescribing guidelines and instructive polices to encourage the rational and appropriate utilization of medications especially antibiotics in dentistry.

OBJECTIVE

The aim of this study was to identify the frequency of antibiotic prescription for treating dental infections in children among dentists in teaching institutions of Karachi, Pakistan and whether they are adhering to the prescribed international guidelines.

METHODS

A cross-sectional study was conducted in three private and two public colleges of Karachi. After taking written informed consent and checking the inclusion criteria, a total of 380 participants were interviewed using a pre-designed validated questionnaire which included demographic profile and clinical case scenarios. Data were entered and analyzed on SPSS version 20. Inferential analysis was performed using chi-square test. The significance level was set at 0.05.

RESULTS

Of the 380 subjects, a majority (71.3%) treated 15 or less children per month (n = 271) while 28.7% of dentists (n = 109) treated more than 15 children per month. Overall adherence to American Academy of Pediatric Dentistry guidelines was low from 26.1% to 44.2%. The difference between adherence of dentists with low and high volume of pediatric patients was significantly different for case scenarios 1, 3, 4 and 5 (p<0.001 for all) where dentists who treated 15 or less children per month were more likely to be adherent to standard antibiotic prescription guidelines than those who treated more than 15 children per month.

CONCLUSIONS

This study shows that majority of dentists, particularly dentists with high volume of pediatric patients lacked adherence to professional guidelines for prescribing antibiotics for treating dental infection in children. There seem to be a lack of harmony between the recommended professional guidelines and the antibiotic prescribing pattern of dentists. Regular updates and continuing medical education for the health professionals regarding comprehensible and specific professional guidelines may lead to improved adherence of antibiotics prescription amongst dentists.

Green Synthesized Phytochemically (Zingiber officinale and Allium sativum) Reduced Nickel Oxide Nanoparticles Confirmed Bactericidal and Catalytic Potential

Phyto-synthesized nanoparticles (NPs) having reduced chemical toxicity have been focused globally and become essential component of nanotechnology recently. We prepared green phytochemically (ginger and garlic) reduced NiO-NPs to replace synthetic bactericidal and catalytic agent in textile industry. NPs were characterized using ultra-violet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesis of NPs was confirmed by XRD and UV-Vis having strong absorption at 350 nm with size ranged between 16-52 nm for ginger and 11-59 nm for garlic. Scanning and transmission electron microscopy confirmed pleomorphism with cubic- and more spherical-shaped NPs. Moreover, exact quantities of garlic and ginger extracts (1:3.6 ml) incorporated to synthesize NiO-NPs have been successfully confirmed by FTIR. Phytochemically reduced NPs by garlic presented enhanced bactericidal activity against multiple drug-resistant Staphylococcus aureus at increasing concentrations (0.5, 1.0 mg/50 μl) and also degraded methylene blue (MB) dye efficiently. Conclusively, green synthesized NiO-NPs are impending activists to resolve drug resistance as well as environment friendly catalytic agent that may be opted at industrial scale.

Antimicrobial and antibiofilm activities of Clostridium butyricum supernatant against Acinetobacter baumannii

Acinetobacter baumannii is the major nosocomial pathogen that causes serious infections such as ventilator-associated pneumonia and bacteremia due to its biofilms. Hence, this study investigated the antimicrobial and antibiofilm potentials of cell-free supernatants (CFS) obtained from Clostridium butyricum, as probiotic, against A. baumannii. Our results demonstrated that C. butyricum CFS inhibited A. baumannii cell growth in planktonic culture. Also, C. butyricum CFS not only inhibited the biofilm development and dispersed mature biofilms, but also suppressed the metabolic activity of biofilm cells, showing antibiofilm activity. The biofilm components reduced by C. butyricum CFS were observed via confocal laser scanning microscopy. In addition, C. butyricum CFS exhibited antivirulence effect by inhibiting the motility of A. baumannii. Furthermore, C. butyricum CFS significantly downregulated the expression of efflux pump-related genes including adeA, adeB and adeC in A. baumannii. Our data demonstrate that C. butyricum CFS showed antimicrobial and antibiofilm effects on A. baumannii. These effects are closely associated with suppression of motility and efflux pump-related genes in A. baumannii. The findings suggest that C. butyricum CFS can be used as a new therapeutic alternative against biofilm-associated infection caused by multidrug-resistant A. baumannii.

Susceptibility of oral bacteria to antibacterial photodynamic therapy

Effective methods for managing the oral microbiome are necessary to ensure not only the oral but also the systemic health of a human body. The purpose of this study was to determine the sensitivity of four photosensitizers (PSs) to blue light in six representative oral bacterial species that cause intraoral diseases. The following six strains were investigated: Actinomyces israelii, Enterococcus faecium, Fusobacterium nucleatum, Lactobacillus gasseri, Streptococcus mutans, Veillonella parvula. PS stock solutions (1 mg/ml) were prepared by dissolving curcumin and protoporphyrin-IX in dimethyl sulfoxide, and resazurin and riboflavin in distilled water. The inoculation of 20 ml of a bacterial suspension cultured for 24 hours was mixed with 1,980 ml of each test solution, and then a light source was placed in front of the mixture. The irradiation wavelength was 405 nm and its applied energy was 25.3 J. The independent-samples t-test and one-way analysis of variance within groups were performed to compare the antibacterial effects in the four PSs. The antibacterial susceptibility when using different PSs and visible blue-light irradiation differed between the bacterial strains. Antibacterial photodynamic therapy that includes light exposure and PSs can be used to control the oral bacteria strains related to oral disease.

Veterinary medicinal product usage among food animal producers and its health implications in Central Ethiopia

Background

Antimicrobials and anthelmintics are the most commonly used veterinary drugs to control animal diseases. However, widespread use of these drugs could contribute to the emergence of drug resistance. Information on the practice of antimicrobial usage among food animal raising communities in Central Ethiopia is scarce. We used a standardised questionnaire survey to assess knowledge, awareness, and practices related to drug use and resistance in food animals among the farmers in and around Bishoftu town.

Results

Of the total of 220 livestock owners interviewed, around 80% of the respondents were not able to define what antimicrobials are and for what purposes they are used. Only 14.1% (n = 31) of the respondents had awareness about antimicrobial resistance (AMR) and its consequences; and 35.5% (n = 11/31) and 9.7% (n = 3/31) of them agreed that the irrational use of antimicrobials in animals could lead to AMR in animals and humans. Oxytetracycline was the most commonly available antibiotic in veterinary drug shops/pharmacies and the most widely used drug in the area. However, 43.3% of the respondents did not see clinical improvements after using antibiotics. Similarly, the respondents explained that no response was observed in 73.3, 70.8 and 52.5% of the cases after medication with anthelmintics, antiprotozoal and acaricides, respectively. About 56.7% of the respondents considered traditional medicines equally important to modern medicines. It was also noted that there were illegal drug vendors, dispensing medicines under unfavourable conditions which include a direct exposure to sunlight, which practice violates the drug handling and storage recommendations given by WHO.

Conclusion

The study revealed that there is a general lack of awareness among food animal owners about the correct use of antibiotics and anthelmintics. The widespread misuse and improper drug dispensing and handling practices observed in this study can affect the drug quality and can also contribute to the development of drug resistance in central Ethiopia.

Antimicrobial usage by pastoralists in food animals in North-central Nigeria: The associated socio-cultural drivers for antimicrobials misuse and public health implications

Antimicrobials are used to maintain good health and productivity of food animals. Misuse of antibiotics in livestock contributes to development of antimicrobial resistance, an emerging One Health issue. This study assessed pastoralists' knowledge and practices regarding antimicrobial usage, explore pathways for resistant pathogens emergence and associated social drivers for antimicrobial misuse in pastoral herds of North-central Nigeria. An interview questionnaire-based cross-sectional survey was conducted in randomly selected pastoral households. Descriptive and analytical statistical analyses were performed at 95% confidence level. All the 384 pastoralists participated in the study. Majority (58%) of respondents had no formal education. Only 8.1% of respondents knew antibiotic misuse to be when given under-dose and 70.1% of them did not know what misuse entailed. About 58.3% reported self-prescription of antimicrobials used on animals, while 67% of them reported arbitrary applications for dosage determination. Most frequently used antimicrobials were tetracycline (96.6%), tylosin (95.6%) and penicillin (94.0%). Identified pathways for antimicrobial resistant pathogens spread to humans were through contaminated animal products; contaminated animals and fomites; and environmental wastes. Improper antimicrobial usage (p < 0.001), non-enforcement of laws regulating antimicrobial usage (p < 0.001), weak financial status (p < 0.001), low education and expertise (p < 0.001), and nomadic culture (p < 0.001), influenced antimicrobials misuse in livestock. The study revealed low levels of knowledge and practices regarding antimicrobial usage in livestock. Socio-cultural activities significantly influenced antimicrobials misuse in livestock. Improve pastoralists' knowledge about effects of antimicrobials misuse and promotion of prudent usage in livestock will mitigate antimicrobial resistance menace in animals and humans.

Effect of Photodynamic Antibacterial Chemotherapy Combined with Antibiotics on Gram-Positive and Gram-Negative Bacteria

The well-known and rapidly growing phenomenon of bacterial resistance to antibiotics is caused by uncontrolled, excessive and inappropriate use of antibiotics. One of alternatives to antibiotics is Photodynamic Antibacterial Chemotherapy (PACT). In the present study, the effect of PACT using a photosensitizer Rose Bengal alone and in combination with antibiotics including methicillin and derivatives of sulfanilamide synthesized by us was tested against antibiotic-sensitive and antibiotic-resistant clinical isolates of Gram-positive S. aureus and Gram-negative P. aeruginosa. Antibiotic-sensitive and resistant strains of P. aeruginosa were eradicated by Rose Bengal under illumination and by sulfanilamide but were not inhibited by new sulfanilamide derivatives. No increase in sensitivity of P. aeruginosa cells to sulfanilamide was observed upon a combination of Rose Bengal and sulfanilamide under illumination. All tested S. aureus strains (MSSA and MRSA) were effectively inhibited by PACT. When treated with sub-MIC concentrations of Rose Bengal under illumination, the minimum inhibitory concentrations (MIC) of methicillin decreased significantly for MSSA and MRSA strains. In some cases, antibiotic sensitivity of resistant strains can be restored by combining antibiotics with PACT.

Prediction of Antimicrobial Potential of a Chemically Modified Peptide From Its Tertiary Structure

Designing novel antimicrobial peptides is a hot area of research in the field of therapeutics especially after the emergence of resistant strains against the conventional antibiotics. In the past number of in silico methods have been developed for predicting the antimicrobial property of the peptide containing natural residues. This study describes models developed for predicting the antimicrobial property of a chemically modified peptide. Our models have been trained, tested and evaluated on a dataset that contains 948 antimicrobial and 931 non-antimicrobial peptides, containing chemically modified and natural residues. Firstly, the tertiary structure of all peptides has been predicted using software PEPstrMOD. Structure analysis indicates that certain type of modifications enhance the antimicrobial property of peptides. Secondly, a wide range of features was computed from the structure of these peptides using software PaDEL. Finally, models were developed for predicting the antimicrobial potential of chemically modified peptides using a wide range of structural features of these peptides. Our best model based on support vector machine achieve maximum MCC of 0.84 with an accuracy of 91.62% on training dataset and MCC of 0.80 with an accuracy of 89.89% on validation dataset. To assist the scientific community, we have developed a web server called "AntiMPmod" which predicts the antimicrobial property of the chemically modified peptide. The web server is present at the following link (http://webs.iiitd.edu.in/raghava/antimpmod/).

Assessment of General Public's Knowledge and Opinions towards Antibiotic Use and Bacterial Resistance: A Cross-Sectional Study in an Urban Setting, Rufisque, Senegal

Background: Bacterial resistance is a major public health problem worldwide. One solution to this scourge is to sensitize the general public on rational use of antibiotics. Our goal was to assess people’s knowledge and opinions about antibiotic use and bacterial resistance in an urban setting. Method: We performed a cross-sectional study. A convenience sampling was done. A questionnaire was administered to 400 persons during face-to-face interviews. Results: Most respondents thought that antibiotics are effective against colds/flu (69.8%), cough (72.3%) and sore throat (64.4%). At the same time, 42.8% stated that antibiotic therapy can be stopped as soon as the symptoms disappear. Only 8.8% and 41.8% of people knew that handwashing and vaccination prevented bacterial resistance. Globally, 7% of people had a good knowledge. Socio-demographic variables were not associated with the level of knowledge. The main sources of information were entourage and pharmacy staff. Regarding the opinions, 78.3% of surveyed participants the people thought that that people overuse antibiotics. Additionally, 28% said that they have no role to play against bacterial resistance. Conclusion: People living in an urban setting had a low knowledge about antibiotic use and bacterial resistance. There is a need to implement awareness campaigns. Further studies on population practices toward antibiotic use are necessary.

Silver-, calcium-, and copper molybdate compounds: Preparation, antibacterial activity, and mechanisms

Developing novel compounds with antimicrobial properties can be an effective approach to decreasing the number of healthcare-associated infections, particularly in the context of medical devices and touch surfaces. A variety of molybdate powders (Ag₂MoO₄, CaMoO₄, CuMoO₄ and Cu₃Mo₂O₉) were synthesized and characterized, and Escherichia coli was used as a model gram-negative bacterium to demonstrate their antimicrobial properties. Optical density measurements, bacterial colony growth, and stained gel images for protein expression clearly showed that silver- and copper molybdates inhibit bacterial growth, whereas CaMoO₄ exhibited no bactericidal effect. All tests were performed in both daylight and darkness to assess the possible contribution of a photocatalytic effect on the activity observed. The main mechanism responsible for the antibacterial effect observed for Ag₂MoO₄ is related to Ag⁺ release in combination with medium acidification, whereas for compounds containing copper, leaching of Cu²⁺ ions is proposed. All these effects are known to cause damage at the cellular level. A photocatalytic contribution to the antibacterial activity was not clearly observable. Based on the pH and solubility measurements performed for powders in contact with various media (ultrapure water and bacterial growth medium), silver molybdate (Ag₂MoO₄) was identified as the best antibacterial candidate. This compound has great potential for further use in hybrid powder-polymer/varnish systems for touch surfaces in healthcare settings.

Assessment of antibiotic use in farm animals in Rwanda

The irrational use of antibiotics in humans and animals is highly related to the emergence and increase of antibiotic-resistant bacteria worldwide. A cross-sectional survey aimed at evaluating the current level of practices regarding antibiotic use in farm animals in Rwanda was carried out countrywide. Interviews were conducted on 229 farmers rearing different types of animals. The study has revealed that almost all respondent farmers could name at least one antibiotic used in farm animals and peni-streptomycin was named by most of them (95.6%). The use of antibiotics in farm animals was observed in the majority of respondents (97.4%). It was found that 44.4 and 26.5% of respondents reported that they used antibiotics for disease prevention and growth promotion, respectively. The use of non-prescribed antibiotics in animals was also reported by more than the half of respondent farmers (55.6%). The majority of farmers had a moderate level of practices regarding antibiotic use in farm animals (73.5%), very few had a high level (26%) and only one respondent had a low level. The high level of practices in regard to antibiotic use in animals was associated with the location of the farm, the type of reared animals, and the rearing system. The results of this study give an insight into antibiotics usage practices in farm animals in Rwanda. The generated information can guide sensitizations and promotions of the prudent use of antibiotics among farmers in order to limit the increase of antibiotic resistance in the country.

Structure-Function Analysis of the Transmembrane Protein AmpG from Pseudomonas aeruginosa

AmpG is a transmembrane protein with permease activity that transports meuropeptide from the periplasm to the cytoplasm, which is essential for the induction of the ampC encoding β-lactamase. To obtain new insights into the relationship between AmpG structure and function, comparative genomics analysis, secondary and tertiary structure modeling, site-directed mutational analyses and genetic complementation experiments were performed in this study. AmpGs from different genera of bacteria (Escherichia coli, Vibrio cholerae and Acinetobacter baumannii) could complement AmpG function in Pseudomonas aeruginosa. The minimal inhibitory concentration (MIC) to ampicillin is 512 μg/ml for wild type strain PAO1, while it is 32 μg/ml for an ampG deletion mutant strain (PAO1ΔampG) with a corresponding decrease in the activity of the ampC-encoded β-lactamase. Site-directed mutagenesis of conserved AmpG residues (G29, A129, Q131 and A197) resulted in a loss of function, resulting in a loss of resistance to ampicillin in PAO1ΔampG. The G29A, G29V, A129T, A129V, A129D, A197S and A197D mutants had lower resistance to ampicillin and significantly decreased activity of the AmpC β-lactamase. The G29A, G29V, A129V, A197S and A197D mutants had decreased ampG mRNA transcript levels. The A129T and A129D mutants had normal ampG mRNA transcript levels, but the function of the protein was drastically reduced. Our experimental results demonstrate that the conserved amino acids played essential roles in maintaining the function of AmpG. Combined with the AmpG structural information, these critical amino acids can be targeted for the development of new anti-bacterial agents.

Antibacterial, Structural and Optical Characterization of Mechano-Chemically Prepared ZnO Nanoparticles

Structural investigations, optical properties and antibacterial performance of the pure Zinc Oxide (ZnO) nanoparticles (NPs) synthesized by mechano-chemical method are presented. The morphology, dimensions and crystallinity of the ZnO NPs were controlled by tweaking the mechanical agitation of the mixture and subsequent thermal treatment. ZnO nanoparticles in small (< 20 nm) dimensions with spherical morphology and narrow size distribution were successfully obtained after treating the mechano-chemically prepared samples at 250°C. However, higher temperature treatments produced larger particles. TEM, XRD and UV-Vis spectroscopy results suggested crystalline and phase pure ZnO. The NPs demonstrated promising antibacterial activity against Gram negative foodborne and waterborne bacterial pathogens i.e. Enteropathogenic E. coli (EPEC), Campylobacter jejuni and Vibrio cholerae as well as Gram positive methicillin resistant Staphylococcus aureus (MRSA), thus potential for medical applications. Scanning electron microscopy and survival assay indicated that most probably ZnO nanoparticles cause changes in cellular morphology which eventually causes bacterial cell death.

Microbicidal activity of TiO2 nanoparticles synthesised by sol-gel method

In this study, the authors investigated antimicrobial activity of TiO2 nanoparticles (NPs) synthesised by sol-gel method. As synthesised TiO2 NPs were characterised by X-ray diffraction, scanning electron microscopy and ultraviolet-visible absorption spectroscopy. The antimicrobial activity of calcined TiO2 nanoparticle samples was examined in day light on Gram positive bacteria (Staphylococcus aureus, Streptococcus pneumonia and Bacillus subtilis), Gram negative bacteria (Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli) and fungal test pathogen Candida albicans. The synthesised TiO2 NPs were found to be effective in visible light against Streptococcus pneumonia, Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa and Candida albicans.

Exploring the evidence base for national and regional policy interventions to combat resistance

The effectiveness of existing policies to control antimicrobial resistance is not yet fully understood. A strengthened evidence base is needed to inform effective policy interventions across countries with different income levels and the human health and animal sectors. We examine three policy domains-responsible use, surveillance, and infection prevention and control-and consider which will be the most effective at national and regional levels. Many complexities exist in the implementation of such policies across sectors and in varying political and regulatory environments. Therefore, we make recommendations for policy action, calling for comprehensive policy assessments, using standardised frameworks, of cost-effectiveness and generalisability. Such assessments are especially important in low-income and middle-income countries, and in the animal and environmental sectors. We also advocate a One Health approach that will enable the development of sensitive policies, accommodating the needs of each sector involved, and addressing concerns of specific countries and regions.

Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

Background

Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe₂O₃ nanoparticles against Gram-positive and Gram-negative bacteria.

Methods and results

Nanosized particles of three metal oxides (ZnO, CuO, and Fe₂O₃) were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe₂O₃, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria.

Conclusion

Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe₂O₃ nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe₂O₃.

Bacterial infections in Lilongwe, Malawi: aetiology and antibiotic resistance

Background

Life-threatening infections present major challenges for health systems in Malawi and the developing world because routine microbiologic culture and sensitivity testing are not performed due to lack of capacity. Use of empirical antimicrobial therapy without regular microbiologic surveillance is unable to provide adequate treatment in the face of emerging antimicrobial resistance. This study was conducted to determine antimicrobial susceptibility patterns in order to inform treatment choices and generate hospital-wide baseline data.

Methods

Culture and susceptibility testing was performed on various specimens from patients presenting with possible infectious diseases at Kamuzu Central Hospital, Lilongwe, Malawi.

Results

Between July 2006 and December 2007 3104 specimens from 2458 patients were evaluated, with 60.1% from the adult medical service. Common presentations were sepsis, meningitis, pneumonia and abscess. An etiologic agent was detected in 13% of patients. The most common organisms detected from blood cultures were Staphylococcus aureus, Escherichia coli, Salmonella species and Streptococcus pneumoniae, whereas Streptococcus pneumoniae and Cryptococcus neoformans were most frequently detected from cerebrospinal fluid. Haemophilus influenzae was rarely isolated. Resistance to commonly used antibiotics was observed in up to 80% of the isolates while antibiotics that were not commonly in use maintained susceptibility.

Conclusions

There is widespread resistance to almost all of the antibiotics that are empirically used in Malawi. Antibiotics that have not been widely introduced in Malawi show better laboratory performance. Choices for empirical therapy in Malawi should be revised accordingly. A microbiologic surveillance system should be established and prudent use of antimicrobials promoted to improve patient care.