Origin and proliferation of multiple-drug resistance in bacterial pathogens

Can Porphyrin-Triphenylphosphonium Conjugates Enhance the Photosensitizer Performance Toward Bacterial Strains?

Antimicrobial photodynamic treatment (aPDT) offers an alternative option for combating microbial pathogens, and in this way, addressing the challenges of growing antimicrobial resistance. In this promising and effective approach, cationic porphyrins and related macrocycles have emerged as leading photosensitizers (PS) for aPDT. In general, their preparation occurs via N-alkylation of nitrogen-based moieties with alkyl halides, which limits the ability to fine-tune the features of porphyrin-based PS. Herein, is reported that the conjugation of porphyrin macrocycles with triphenylphosphonium units created a series of effective cationic porphyrin-based PS for aPDT. The presence of positive charges at both the porphyrin macrocycle and triphenylphosphonium moieties significantly enhances the photodynamic activity of porphyrin-based PS against both Gram-positive and Gram-negative bacterial strains. Moreover, bacterial photoinactivation is achieved with a notable reduction in irradiation time, exceeding 50%, compared to 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP), used as the reference and known as good PS. The improved capability of the porphyrin macrocycle to generate singlet oxygen combined with the enhanced membrane interaction promoted by the presence of triphenylphosphonium moieties represents a promising approach to developing porphyrin-based PS with enhanced photosensitizing activity.

Genomic diversity and antimicrobial resistance in clinical Klebsiella pneumoniae isolates from tertiary hospitals in Southern Ghana

OBJECTIVES

Comprehensive data on the genomic epidemiology of hospital-associated Klebsiella pneumoniae in Ghana are scarce. This study investigated the genomic diversity, antimicrobial resistance patterns, and clonal relationships of 103 clinical K. pneumoniae isolates from five tertiary hospitals in Southern Ghana-predominantly from paediatric patients aged under 5 years (67/103; 65%), with the majority collected from urine (32/103; 31%) and blood (25/103; 24%) cultures.

METHODS

We generated hybrid Nanopore-Illumina assemblies and employed Pathogenwatch for genotyping via Kaptive [capsular (K) locus and lipopolysaccharide (O) antigens] and Kleborate (antimicrobial resistance and hypervirulence) and determined clonal relationships using core-genome MLST (cgMLST).

RESULTS

Of 44 distinct STs detected, ST133 was the most common, comprising 23% of isolates (n = 23/103). KL116 (28/103; 27%) and O1 (66/103; 64%) were the most prevalent K-locus and O-antigen types. Single-linkage clustering highlighted the global spread of MDR clones such as ST15, ST307, ST17, ST11, ST101 and ST48, with minimal allele differences (1-5) from publicly available genomes worldwide. Conversely, 17 isolates constituted novel clonal groups and lacked close relatives among publicly available genomes, displaying unique genetic diversity within our study population. A significant proportion of isolates (88/103; 85%) carried resistance genes for ≥3 antibiotic classes, with the blaCTX-M-15 gene present in 78% (n = 80/103). Carbapenem resistance, predominantly due to blaOXA-181 and blaNDM-1 genes, was found in 10% (n = 10/103) of the isolates.

CONCLUSIONS

Our findings reveal a complex genomic landscape of K. pneumoniae in Southern Ghana, underscoring the critical need for ongoing genomic surveillance to manage the substantial burden of antimicrobial resistance.

Anti-Infection of Oral Microorganisms from Herbal Medicine of Piper crocatum Ruiz & Pav

The WHO Global Status Report on Oral Health 2022 reveals that oral diseases caused by infection with oral pathogenic microorganisms affect nearly 3.5 billion people worldwide. Oral health problems are caused by the presence of S. mutans, S. sanguinis, E. faecalis and C. albicans in the oral cavity. Synthetic anti-infective drugs have been widely used to treat oral infections, but have been reported to cause side effects and resistance. Various strategies have been implemented to overcome this problem. Synthetic anti-infective drugs have been widely used to treat oral infections, but they have been reported to cause side effects and resistance. Therefore, it is important to look for safe anti-infective alternatives. Ethnobotanical and ethnopharmacological studies suggest that Red Betel leaf (Piper crocatum Ruiz & Pav) could be a potential source of oral anti-infectives. This review aims to discuss the pathogenesis mechanism of several microorganisms that play an important role in causing health problems, the mechanism of action of synthetic oral anti-infective drugs in inhibiting microbial growth in the oral cavity, and the potential of red betel leaf (Piper crocatum Ruiz & Pav) as an herbal oral anti-infective drug. This study emphasises the importance of researching natural components as an alternative treatment for oral infections that is more effective and can meet global needs.

Effectiveness of 5-aminolevulinic acid photodynamic therapy in treating dissecting cellulitis of the scalp and pathological changes in skin lesions: A retrospective study

BACKGROUND

Dissecting cellulitis of the scalp (DCS) has a significant impact on the physical well-being and body image of the patient. Since DCS often responds poorly to conventional treatments, there is a need to identify alternative treatment strategies. This study aimed to explore the effectiveness of 5-aminolevulinic acid photodynamic therapy (ALA-PDT) in treating DCS.

METHODS

Twelve male patients with DCS treated solely with ALA-PDT between June 2022 and June 2023 at our institution were enrolled in this study. Two patients underwent a biopsy before and after treatment for comparison. The efficacy of the treatments was assessed 10 days after treatment by evaluating the symptom scores recorded on medical records and by assessing the photographs acquired before and after treatment. In addition, the impact of the treatment on pain relief and median recurrence rate were also extracted.

RESULTS

Out of the 12 enrolled patients, the majority of the patients (75%) had a significant reduction in the nodules or abscesses. The pain relief was significant in 3 patients (25%), and moderate in 7 patients (58.3%). For the subcutaneous sinus tract symptoms, 3 patients (27.3%) showed moderate improvement, and 7 (63.6%) had a mild improvement. Six patients (75%) had mild improvement in their alopecia. The pathology results showed a decrease in the number of lymphocytes, macrophages, and neutrophils within the skin lesions following the administration of ALA-PDT.

CONCLUSION

ALA-PDT can effectively reduce the DCS symptoms and the number of lymphocytes, macrophages, and neutrophils within the skin lesions.

The modern alchemy of clinical pathology: turning the output of microbiology laboratory operations into gold

The clinical microbiology laboratory generates a huge amount of high-quality data that play a vital role in clinical care. With proper extraction, cleaning, analysis, and validation pipelines, these data can serve multiple other purposes that include supporting laboratory operations, understanding local epidemiology, informing hospital-specific policies, and public health surveillance. In this review, I use one of the core activities of the microbiology laboratory, antimicrobial susceptibility testing (AST), to illustrate several potential applications of next-generation data analytics. The first involves continuous monitoring of commercial AST systems using comparisons of minimum inhibitory concentration (MIC) distributions over time to trigger re-verification when statistically significant differences are detected. An extension of this is temporal analysis of joint MIC distributions to understand performance for multidrug-resistant organisms. More sophisticated analyses involve linking microbiologic data to clinical metadata to gain insight into the clinical validity of AST data and to inform treatment policies. The elements of a robust, validated analysis engine using routine data streams already exist, but numerous challenges must be overcome to make it a reality. Most importantly, it will require the sustained collaboration and advocacy of hospital leadership, microbiologists, clinicians, antimicrobial stewardship, data scientists, and regulatory agencies. Though no small feat, achieving this vision would provide an important resource for microbiology laboratories facing a rapidly evolving practice landscape and further cement its role as an integral part of a learning health system.

Diagnostics for Public Health - Infectious Disease Surveillance and Control

AbstractAccurate diagnostics are critical in public health to ensure successful disease tracking, prevention, and control. Many of the same characteristics are desirable for diagnostic procedures in both medicine and public health: for example, low cost, high speed, low invasiveness, ease of use and interpretation, day-to-day consistency, and high accuracy. This review lays out five principles that are salient when the goal of diagnosis is to improve the overall health of a population rather than that of a particular patient, and it applies them in two important use cases: pandemic infectious disease and antimicrobial resistance.

Antimicrobial Resistance and Biofilm Formation of Bordetella bronchiseptica in Central China, with Evidence of a Rare Heteroresistance Strain to Gentamicin

Bordetella bronchiseptica is a significant contributor to respiratory disease in pigs, leading to substantial economic losses in the swine industry worldwide. We isolated 52 B. bronchiseptica strains from 542 samples collected from pigs with atrophic rhinitis and bronchopneumonia in central China. Multi-locus sequence typing identified two prevalent sequence types: ST6 (69.23%) and ST7 (30.77%). PCR-based detection of seven virulence genes (fhaB, prn, cyaA, dnt, bteA, fla, and bfrZ) revealed that six of these genes were present in over 90% of the isolates, with bfrZ being the exception at 59.62%. Antimicrobial susceptibility testing, performed using the K-B method, demonstrated high sensitivity to enrofloxacin, polymyxin, and doxycycline but a notable resistance to tylosin, trimethoprim, tobramycin, ciprofloxacin, and amikacin. Remarkably, 86.54% of the isolates exhibited a multidrug-resistant phenotype. Notably, we successfully screened a strain of B. bronchiseptica with a heteroresistance phenotype to gentamicin using population analysis profiling, which is a rare case. Biofilm-formation assays indicated that 96.15% of the isolates possessed biofilm-forming capabilities. These findings provide crucial insights into the prevalence of B. bronchiseptica in central China, facilitating the development of effective preventive measures to safeguard both animal and human health.

Antimicrobial potential of phytocompounds of Acorus calamus: in silico approach

Medicinal plants are used from prehistoric time to cure various life-threatening bacterial diseases. Acorus calamus is an important medicinal plant widely used to cure gastrointestinal, respiratory, kidney and liver disorders. The objective of the current research was to investigate the interaction of major phytoconstituents of Acorus calamus with bacterial (6VJE) and fungal (1EA1) protein targets. Protein-ligand interactions were estimated using the AutoDock software, drug likeness was predicted by using the molinspiration server and toxicity was predicted with the swissADME and protox II servers. MD simulation of phytocompounds with the best profiles was done on the GROMACS software for 100 ns. Molecular docking results showed among all the selected major phytoconstituents, that β-cadinene showed best binding interaction in complex with bacterial (6VJE) and fungal (1EA1) protein targets with binding energy -7.66 ± 0.1 and -7.73 ± 0.15 kcal mol-1, respectively. Drug likeness and toxicity predictions showed that β-cadinene follows all rules of drug likeness and toxicity. MD simulation study revealed that β-cadinene fit in binding pocket of bacterial and fungal targets and found to be stable throughout the duration of the simulation. Based on the observations from this in-silico study it is being proposed that β-cadinene, a major phytocompound of Acorus calamus, can be considered for the treatment of bacterial and fungal infections since the study shows that it might be one of the compounds that contributes majorly to the plant's biological activity. This study needs in vitro and in vivo validation.Communicated by Ramaswamy H. Sarma.

HILIC-IM-MS for Simultaneous Lipid and Metabolite Profiling of Bacteria

Although MALDI-ToF platforms for microbial identifications have found great success in clinical microbiology, the sole use of protein fingerprints for the discrimination of closely related species, strain-level identifications, and detection of antimicrobial resistance remains a challenge for the technology. Several alternative mass spectrometry-based methods have been proposed to address the shortcomings of the protein-centric approach, including MALDI-ToF methods for fatty acid/lipid profiling and LC-MS profiling of metabolites. However, the molecular diversity of microbial pathogens suggests that no single "ome" will be sufficient for the accurate and sensitive identification of strain- and susceptibility-level profiling of bacteria. Here, we describe the development of an alternative approach to microorganism profiling that relies upon both metabolites and lipids rather than a single class of biomolecule. Single-phase extractions based on butanol, acetonitrile, and water (the BAW method) were evaluated for the recovery of lipids and metabolites from Gram-positive and -negative microorganisms. We found that BAW extraction solutions containing 45% butanol provided optimal recovery of both molecular classes in a single extraction. The single-phase extraction method was coupled to hydrophilic interaction liquid chromatography (HILIC) and ion mobility-mass spectrometry (IM-MS) to resolve similar-mass metabolites and lipids in three dimensions and provide multiple points of evidence for feature annotation in the absence of tandem mass spectrometry. We demonstrate that the combined use of metabolites and lipids can be used to differentiate microorganisms to the species- and strain-level for four of the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa) using data from a single ionization mode. These results present promising, early stage evidence for the use of multiomic signatures for the identification of microorganisms by liquid chromatography, ion mobility, and mass spectrometry that, upon further development, may improve upon the level of identification provided by current methods.

Crosslinking kiwifruit-derived DNA with natural aromatic aldehydes generates membranolytic antibacterial nanogels

Improper use of antibiotics has led to the global rise of drug-resistant biofilm bacteria. Thus, researchers have been increasingly interested in green materials that are highly biocompatible and have low toxicity. Here, nanogels (NGs) with imine bonds were synthesized by crosslinking kiwifruit-derived DNA's primary amine and aromatic aldehydes (cuminaldehyde, p-anisaldehyde, or vanillin) under water-in-hexane emulsion processes. Transmission electron microscope showed that the NGs had spherical geometry with an average particle size ranging from 40 to 140 nm and that the zeta potential indicated a negative charge. Additionally, the DNA-aromatic aldehyde NGs showed low cytotoxicity toward normal cell organoids and human RBCs in cell viability tests. These NGs were also tested against four pathogenic bacteria for various assays. DNA-vanillin (DNA-VA) NGs exhibited significant antibacterial effects against bacteria with very low inhibitory concentrations as seen in a minimum inhibitory concentration assay. Scanning electron microscope observation revealed that the bacteria were deformed, and immunoblotting detected intracellular groEL protein expression. In agreement with these results, DNA-aromatic aldehyde NGs successfully protected C. elegans from P. aeruginosa-induced lethality. These DNA NGs provided a multivalent 3D space for antibacterial aromatic aldehydes to tether, enhancing their interaction with the bacterial wall. These results offer a new direction for the development of novel antibiotics in the future.

Rational Design of Amphipathic Antimicrobial Peptides with Alternating L-/D-Amino Acids That Form Helical Structures

Antimicrobial peptides (AMPs) are promising therapeutic agents against bacteria. We have previously reported an amphipathic AMP Stripe composed of cationic L-Lys and hydrophobic L-Leu/L-Ala residues, and Stripe exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria. Gramicidin A (GA), composed of repeating sequences of L- and D-amino acids, has a unique β6.3-helix structure and exhibits broad antimicrobial activity. Inspired by the structural properties and antimicrobial activities of LD-alternating peptides such as GA, in this study, we designed Stripe derivatives with LD-alternating sequences. We found that simply alternating L- and D-amino acids in the Stripe sequence to give StripeLD caused a reduction in antimicrobial activity. In contrast, AltStripeLD, with cationic and hydrophobic amino acids rearranged to yield an amphipathic distribution when the peptide adopts a β6.3-helix, displayed higher antimicrobial activity than AltStripe. These results suggest that alternating L-/D-cationic and L-/D-hydrophobic amino acids in accordance with the helical structure of an AMP may be a useful way to improve antimicrobial activity and develop new AMP drugs.

The Discovery of Novel Agents against Staphylococcus aureus by Targeting Sortase A: A Combination of Virtual Screening and Experimental Validation

Staphylococcus aureus (S. aureus), commonly known as "superbugs", is a highly pathogenic bacterium that poses a serious threat to human health. There is an urgent need to replace traditional antibiotics with novel drugs to combat S. aureus. Sortase A (SrtA) is a crucial transpeptidase involved in the adhesion process of S. aureus. The reduction in virulence and prevention of S. aureus infections have made it a significant target for antimicrobial drugs. In this study, we combined virtual screening with experimental validation to identify potential drug candidates from a drug library. Three hits, referred to as Naldemedine, Telmisartan, and Azilsartan, were identified based on docking binding energy and the ratio of occupied functional sites of SrtA. The stability analysis manifests that Naldemedine and Telmisartan have a higher binding affinity to the hydrophobic pockets. Specifically, Telmisartan forms stable hydrogen bonds with SrtA, resulting in the highest binding energy. Our experiments prove that the efficiency of adhesion and invasion by S. aureus can be decreased without significantly affecting bacterial growth. Our work identifies Telmisartan as the most promising candidate for inhibiting SrtA, which can help combat S. aureus infection.

Wastewater-Based Surveillance of Antimicrobial Resistance in Niger: An Exploratory Study

Wastewater-based surveillance is increasingly recognized as an important approach to monitoring population-level antimicrobial resistance (AMR). In this exploratory study, we examined the use of metagenomics to evaluate AMR using untreated wastewater samples routinely collected by the Niger national polio surveillance program. Forty-eight stored samples from two seasons each year over 4 years (2016-2019) in three regions were selected for inclusion in this study and processed using unbiased DNA deep sequencing. Normalized number of reads of genetic determinants for different antibiotic classes were compared over time, by season, and by location. Correlations in resistance were examined among classes. Changes in reads per million per year were demonstrated for several classes, including decreases over time in resistance determinants for phenicols (-3.3, 95% CI: -8.7 to -0.1, P = 0.029) and increases over time for aminocoumarins (3.8, 95% CI: 0.0 to 11.4, P = 0.043), fluoroquinolones (6.8, 95% CI: 0.0 to 20.5, P = 0.048), and beta-lactams (0.85, 95% CI: 0.1 to 1.7, P = 0.006). Sulfonamide resistance was higher in the post-rainy season compared with the dry season (5.2-fold change, 95% CI: 3.4 to 7.9, P < 0.001). No differences were detected when comparing other classes by season or by site for any antibiotic class. Positive correlations were identified in genetic determinants of resistance among several antibiotic classes. These results demonstrate the potential utility of leveraging existing wastewater sample collection in this setting for AMR surveillance.

Photodynamic therapy: a new approach to the treatment of Nontuberculous Mycobacterial skin and soft tissue infections

Nontuberculous mycobacterial skin and soft tissue infections are rising and are causing social concern due to the growth of cosmetic dermatology and immune-compromised populations. For the treatment of nontuberculous mycobacteria, several novel strategies have been investigated. One of them, photodynamic therapy, is a recently developed therapeutic strategy that has shown promise in managing nontuberculous mycobacterial skin and soft tissue infections. In this review, we first present an overview of the current status of the therapy and then summarize and analyze the cases of photodynamic therapy used to treat nontuberculous mycobacterial skin and soft tissue infections. We also discussed the feasibility of photodynamic therapy for treating nontuberculous mycobacterial skin soft tissue infections and the related mechanisms, providing a potential new option for clinical treatment.

Fish collagen peptides' modulating effect on human skin microbiota against pathogenic Staphylococcus aureus

Aim: The current research aims to design effective strategies to enhance the body's immune system against pathogenic bacteria. Methods: Skin commensals were isolated, identified and cultured in fish collagen peptides (FCPs). Results: After culturing in FCP, the skin commensals were used in a dose-dependent manner for Staphylococcus aureus in a dual-culture test, which showed significant growth inhibition of the pathogenic bacteria, which concluded that FCP induced the immune defense system of skin microbiota against pathogenic strains. Conclusion: Results have validated that fish collagen peptide plays a vital role in the growth of selected human skin flora and induces more defensive immunity against pathogenic S. aureus bacteria in dual-culture experimentation.

Evolution of Vaccines Formulation to Tackle the Challenge of Anti-Microbial Resistant Pathogens

The increasing diffusion of antimicrobial resistance (AMR) across more and more bacterial species emphasizes the urgency of identifying innovative treatment strategies to counter its diffusion. Pathogen infection prevention is among the most effective strategies to prevent the spread of both disease and AMR. Since their discovery, vaccines have been the strongest prophylactic weapon against infectious diseases, with a multitude of different antigen types and formulative strategies developed over more than a century to protect populations from different pathogens. In this review, we review the main characteristics of vaccine formulations in use and under development against AMR pathogens, focusing on the importance of administering multiple antigens where possible, and the challenges associated with their development and production. The most relevant antigen classes and adjuvant systems are described, highlighting their mechanisms of action and presenting examples of their use in clinical trials against AMR. We also present an overview of the analytical and formulative strategies for multivalent vaccines, in which we discuss the complexities associated with mixing multiple components in a single formulation. This review emphasizes the importance of combining existing knowledge with advanced technologies within a Quality by Design development framework to efficiently develop vaccines against AMR pathogens.

Cryo-EM-based structural insights into supramolecular assemblies of γ-hemolysin from S. aureus reveal the pore formation mechanism

γ-Hemolysin (γ-HL) is a hemolytic and leukotoxic bicomponent β-pore-forming toxin (β-PFT), a potent virulence factor from the Staphylococcus aureus Newman strain. In this study, we performed single-particle cryoelectron microscopy (cryo-EM) of γ-HL in a lipid environment. We observed clustering and square lattice packing of octameric HlgAB pores on the membrane bilayer and an octahedral superassembly of octameric pore complexes that we resolved at resolution of 3.5 Å. Our atomic model further demonstrated the key residues involved in hydrophobic zipping between the rim domains of adjacent octameric complexes, providing additional structural stability in PFTs post oligomerization. We also observed extra densities at the octahedral and octameric interfaces, providing insights into the plausible lipid-binding residues involved for HlgA and HlgB components. Furthermore, the hitherto elusive N-terminal region of HlgA was also resolved in our cryo-EM map, and an overall mechanism of pore formation for bicomponent β-PFTs is proposed.

Nanosilver/DCOIT-containing surface coating effectively and constantly reduces microbial load in emergency room surfaces

BACKGROUND

Colonization of near-patient surfaces in hospitals plays an important role as a source of healthcare-associated infections. Routine disinfection methods only result in short-term elimination of pathogens.

AIM

To investigate the efficiency of a newly developed antimicrobial coating containing nanosilver in long-term reduction of bacterial burden in hospital surfaces to close the gap between routine disinfection cycles.

METHODS

In this prospective, double-blinded trial, frequently touched surfaces of a routinely used treatment room in an emergency unit of a level-I hospital were treated with a surface coating (nanosilver/DCOIT-coated surface, NCS) containing nanosilver particles and another organic biocidal agent (4,5-dichloro-2-octyl-4-isothiazolin-3-one, DCOIT), whereas surfaces of another room were treated with a coating missing both the nanosilver- and DCOIT-containing ingredient and served as control. Bacterial contamination of the surfaces was examined using contact plates and liquid-based swabs daily for a total trial duration of 90 days. After incubation, total microbial counts and species were assessed.

FINDINGS

In a total of 2880 antimicrobial samples, a significant reduction of the overall bacterial load was observed in the NCS room (median: 0.31 cfu/cm²; interquartile range: 0.00-1.13) compared with the control coated surfaces (0.69 cfu/cm²; 0.06-2.00; P < 0.001). The nanosilver- and DCOIT-containing surface coating reduced the relative risk of a critical bacterial load (defined as >5 cfu/cm²) by 60% (odds ratio 0.38, P < 0.001). No significant difference in species distribution was detected between NCS and control group.

CONCLUSION

Nanosilver-/DCOIT-containing surface coating has shown efficiency for sustainable reduction of bacterial load of frequently touched surfaces in a clinical setting.

Genomic Characteristics and Molecular Epidemiology of Multidrug-Resistant Klebsiella pneumoniae Strains Carried by Wild Birds

This study aimed to explore the relationship between wild birds and the transmission of multidrug-resistant strains. Klebsiella pneumoniae was isolated from fresh feces of captured wild birds and assessed by the broth microdilution method and comparative genomics. Four Klebsiella pneumoniae isolates showed different resistance phenotypes; S90-2 and S141 were both resistant to ampicillin, cefuroxime, and cefazolin, while M911-1 and S130-1 were sensitive to most of the 14 antibiotics tested. S90-2 belongs to sequence type 629 (ST629), and its genome includes 30 resistance genes, including blaCTX-M-14 and blaSHV-11, while its plasmid pS90-2.3 (IncR) carries qacEdelta1, sul1, and aph(3')-Ib. S141 belongs to ST1662, and its genome includes a total of 27 resistance genes, including blaSHV-217. M911-1 is a new ST, carrying blaSHV-1 and fosA6, and its plasmid pM911-1.1 (novel) carries qnrS1, blaLAP-2, and tet(A). S130-1 belongs to ST3753, carrying blaSHV-11 and fosA6, and its plasmid pS130-1 [IncFIB(K)] carries only one resistance gene, tet(A). pM911-1.1 and pS90-2.3 do not have conjugative transfer ability, but their resistance gene fragments are derived from multiple homologous Enterobacteriaceae strain chromosomes or plasmids, and the formation of resistance gene fragments (multidrug resistance region) involves interactions between multiple mobile element genes, resulting in a complex and diverse resistance plasmid structure. The homologous plasmids related to pM911-1.1 and pS90-2.3 were mainly from isolated human-infecting bacteria in China, namely, K. pneumoniae and Escherichia coli. The multidrug-resistant K. pneumoniae isolates carried by wild birds in this study had drug resistance phenotypes conferred primarily by multidrug resistance plasmids that were closely related to human-infecting bacteria. IMPORTANCE Little is known about the pathogenic microorganisms carried by wild animals. This study found that the multidrug resistance phenotype of Klebsiella pneumoniae isolates carried by wild birds was mainly attributed to multidrug resistance plasmids, and these multidrug resistance plasmids from wild birds were closely related to human-infecting bacteria. Wild bird habitats overlap to a great extent with human and livestock habitats, which further increases the potential for horizontal transfer of multidrug-resistant bacteria among humans, animals, and the environment. Therefore, wild birds, as potential transmission hosts of multidrug-resistant bacteria, should be given attention and monitored.

Engineered Biosensors for Diagnosing Multidrug Resistance in Microbial and Malignant Cells

To curtail pathogens or tumors, antimicrobial or antineoplastic drugs have been developed. These drugs target microbial/cancer growth and survival, thereby improving the host's health. In attempts to evade the detrimental effects of such drugs, these cells have evolved several mechanisms over time. Some variants of the cells have developed resistances against multiple drugs or antimicrobial agents. Such microorganisms or cancer cells are said to exhibit multidrug resistance (MDR). The drug resistance status of a cell can be determined by analyzing several genotypic and phenotypic changes, which are brought about by significant physiological and biochemical alterations. Owing to their resilient nature, treatment and management of MDR cases in clinics is arduous and requires a meticulous approach. Currently, techniques such as plating and culturing, biopsy, gene sequencing, and magnetic resonance imaging are prevalent in clinical practices for determining drug resistance status. However, the major drawbacks of using these methods lie in their time-consuming nature and the problem of translating them into point-of-care or mass-detection tools. To overcome the shortcomings of conventional techniques, biosensors with a low detection limit have been engineered to provide quick and reliable results conveniently. These devices are highly versatile in terms of analyte range and quantities that can be detected to report drug resistance in a given sample. A brief introduction to MDR, along with a detailed insight into recent biosensor design trends and use for identifying multidrug-resistant microorganisms and tumors, is presented in this review.

Recent Approaches for Downplaying Antibiotic Resistance: Molecular Mechanisms

Antimicrobial resistance (AMR) is a ubiquitous public health menace. AMR emergence causes complications in treating infections contributing to an upsurge in the mortality rate. The epidemic of AMR in sync with a high utilization rate of antimicrobial drugs signifies an alarming situation for the fleet recovery of both animals and humans. The emergence of resistant species calls for new treatments and therapeutics. Current records propose that health drug dependency, veterinary medicine, agricultural application, and vaccination reluctance are the primary etymology of AMR gene emergence and spread. Recently, several encouraging avenues have been presented to contest resistance, such as antivirulent therapy, passive immunization, antimicrobial peptides, vaccines, phage therapy, and botanical and liposomal nanoparticles. Most of these therapies are used as cutting-edge methodologies to downplay antibacterial drugs to subdue the resistance pressure, which is a featured motive of discussion in this review article. AMR can fade away through the potential use of current cutting-edge therapeutics, advancement in antimicrobial susceptibility testing, new diagnostic testing, prompt clinical response, and probing of new pharmacodynamic properties of antimicrobials. It also needs to promote future research on contemporary methods to maintain host homeostasis after infections caused by AMR. Referable to the microbial ability to break resistance, there is a great ultimatum for using not only appropriate and advanced antimicrobial drugs but also other neoteric diverse cutting-edge therapeutics.

Insights into coastal microbial antibiotic resistome through a meta-transcriptomic approach in Yucatan

Antibiotic resistance (AR) is one of the greatest human and clinical challenges associated with different pathogenic organisms. However, in recent years it has also become an environmental problem due to the widespread use of antibiotics in humans and livestock activities. The ability to resist antibiotics comes from antibiotic resistance genes (ARGs) and our understanding of their presence in coastal environments is still limited. Therefore, the objective of the present study was to explore the presence and possible differences in the microbial resistome of four sites from the Yucatan coast through the evaluation of the composition and abundance of ARGs using a high-throughput analysis of metatranscriptomic sequences. In total, 3,498 ARGs were uncovered, which participate in the resistance to tetracycline, macrolide, rifamycin, fluoroquinolone, phenicol, aminoglycoside, cephalosporin, and other antibiotics. The molecular mechanisms of these ARGs were mainly efflux pump, antibiotic target alteration and antibiotic target replacement. In the same way, ARGs were detected in the samples but showing dissimilar enrichment levels. With respect to the sampling sites, the ARGs were present in all the samples collected, either from preserved or contaminated areas. Importantly, sediments of the preserved area of Dzilam presented the second highest level of ARGs detected, probably as a consequence of the antibiotics dragged to the coast by submarine groundwater discharge. In general, the resistance to a single antibiotic was greater than multiresistance, both at the level of gene and organisms; and multiresistance in organisms is acquired mainly by recruiting different monoresistance genes. To our knowledge, this is the first study that describes and compares the resistome of different samples of the Yucatan coast. This study contributes to generating information about the current state of antibiotic resistance on the Yucatan coasts for a better understanding of ARGs dissemination and could facilitate the management of ARGs pollution in the environment.

Analysis of the Distribution and Antibiotic Resistance of Pathogens Causing Infections in Hospitals from 2017 to 2019

Background. Antibiotic resistance is a global public health problem, leading to high mortality and treatment costs. To achieve more efficient treatment protocols and better patient recovery, the distribution and drug resistance of pathogens in our hospital were investigated, allowing significant clinical guidance for the use of antimicrobials. Methods. In this retrospective study (2017–2019), 3482 positive samples were isolated from 43,981 specimens in 2017; 3750 positive specimens were isolated from 42,923 specimens in 2018; and 3839 positive pathogens were isolated from 46,341 specimens in 2019. These samples were from various parts of the patients, including the respiratory tract, urine, blood, wound secretions, bile, and puncture fluids. The distribution and antibiotic resistance of these isolated pathogens from the whole hospital were analyzed. Results. The results from pathogen isolation showed that Escherichia coli (12.8%), Staphylococcus aureus (11%), Klebsiella pneumoniae (10.8%), Pseudomonas aeruginosa (10.7%), and Acinetobacter baumannii (6.4%) represented the five main pathogenic bacteria in our hospital. Pseudomonas aeruginosa (16.2% and 17.5%) occupied the largest proportion in the central intensive care unit (central ICU) and respiratory intensive care unit (RICU), while Acinetobacter baumannii (15.4%) was the most common pathogen in the emergency intensive care unit (EICU). The resistance rate of Escherichia coli to trimethoprim and minocycline was 100%, and the sensitivity rate to ertapenem, furantoin, and amikacin was above 90%. The resistance rate of Pseudomonas aeruginosa to all antibiotics, such as piperacillin and ciprofloxacin, was under 40%. The sensitivity rate of Acinetobacter baumannii to tigecycline and minocycline was less than 30%, and the resistance rate to many drugs such as piperacillin, ceftazidime, and imipenem was above 60%. Extended-spectrum β-lactamases (ESBLs)-producing Klebsiella pneumoniae (ESBLs-KPN) and carbapenem-resistant Klebsiella pneumoniae (CRE-KPN), ESBLs-producing Escherichia coli (ESBLs-ECO) and carbapenem-resistant Escherichia coli (CRE-ECO), multidrug-resistant Acinetobacter baumannii (MDR-AB), multidrug-resistant Pseudomonas aeruginosa (MDR-PAE), and methicillin-resistant Staphylococcus aureus (MRSA) are all important multidrug-resistant bacteria found in our hospital. The resistance rate of ESBLs-producing Enterobacteriaceae to ceftriaxone and amcarcillin-sulbactam was above 95%. CRE Enterobacteriaceae bacteria showed the highest resistance to amcarcillin-sulbactam (97.1%), and the resistance rates of MDR-AB to cefotaxime, cefepime, and aztreonam were 100%. The resistance rates of MDR-PAE to ceftazidime, imipenem, and levofloxacin were 100%, and the sensitivity rate to polymyxin B was above 98%. The resistance rate of MRSA to oxacillin was 100%, and the sensitivity rate to linezolid and vancomycin was 100%. Conclusion. The distribution of pathogenic bacteria in different hospital departments and sample sources was markedly different. Therefore, targeted prevention and control of key pathogenic bacteria in different hospital departments is necessary, and understanding both drug resistance and multiple drug resistance of the main pathogenic bacteria may provide guidance for the rational use of antibiotics in the clinic.

Whole-genome sequencing-based prediction and analysis of antimicrobial resistance in Yersinia enterocolitica from Ningxia, China

Focusing on resistance trends and transmission patterns of pathogenic microorganisms is a major priority for national surveillance programs. The use of whole-genome sequencing for antimicrobial susceptibility testing (WGS-AST) is a powerful alternative to traditional microbiology laboratory methods. Yersinia enterocolitica antimicrobial resistance (AMR) in the Ningxia Hui Autonomous Region has yet to be described thoroughly in current studies. We assessed and monitored the development of Y. enterocolitica AMR in the Ningxia Hui Autonomous Region during 2007–2019 based on WGS-AST. Resistance genotypes were predicted based on WGS. Antimicrobial resistance testing using classical microbiology determined resistance to 13 antimicrobial agents in 189 Y. enterocolitica isolates from Ningxia. The highest resistance level was 97.88% for cefazolin, followed by ampicillin (AMP) (44.97%), ciprofloxacin (CIP) (25.40%), streptomycin (STR) (11.11%), and tetracycline (TET) (10.58%). Isolates emerged as chloramphenicol (CHL) and trimethoprim/sulfamethoxazole (SXT) resistant. The primary plasmid types were IncFII(Y) and ColRNAI. The TET, STR, and SXT resistance were mediated by the tetA, aph(6)-Id, aph(3″)-Ib, and sul2 genes located on the IncQ1 plasmid. The resistant strains were predominantly biotype 4/O:3/ST429 and the hosts were pigs and patients. The number of multidrug-resistant (MDR) strains was of concern, at 27.51%. At present, the prediction of antimicrobial resistance based on WGS requires a combination of phenotypes. From 2007 to 2019, Y. enterocolitica isolates from the Ningxia Hui Autonomous Region showed a relatively high rate of resistance to cefazolin (CZO) and some resistance to AMP, CIP, STR, and TET. CIP, SXT, and TET showed a relatively clear trend of increasing resistance. Plasmids carrying multiple drug resistance genes are an important mechanism for the spread of antimicrobial resistance. Isolates with low pathogenicity were more likely to present an AMR phenotype than non-pathogenic isolates.

Self-Medication with Antibiotics: Prevalence, Practices and Related Factors among the Pakistani Public

Self-medication with antibiotics (SMA) has become considerably common in developing countries, which is a critical factor for driving antibiotic resistance. Individuals involved in SMA generally do not have adequate knowledge regarding the appropriate use, indications and dosage of these drugs. The objective of the present study was to investigate population SMA practices, knowledge and sociodemographic factors associated with SMA in Islamabad, Pakistan. The study adopted a cross-sectional methodology and data collection was performed through an anonymous, structured and pilot-tested questionnaire, which was interview-administered. Inferential statistics and multivariate logistic regression were performed. Out of 480 participants, 55.6% (n = 267) were male with a mean age of 37.1 ± 10.1 years; the total prevalence of SMA was 32.5%. Ciprofloxacin (42.9%) was the most commonly used antibiotic to treat coughs or colds, a runny nose, flu or sore throat, diarrhea or fevers, which were relevant reasons for SMA. Findings from multivariate logistic regression showed that predictors of SMA were: male gender (95% CI: 0.383–1.005), age (95% CI: 0.317–0.953) and highest level of education (95% CI: 0.961–0.649). Despite reasonable access to healthcare facilities, people are still obtaining antibiotics without prescription, bypassing diagnostic and consultative healthcare services. Thus, the government must implement strict healthcare policies to restrict the sale of antibiotics without prescriptions, while at the same time, targeted public awareness campaigns about the proper use of antibiotics are also required.

Structure-Activity Relationships for 5''-Modifications of 4,5-Aminoglycoside Antibiotics

Modification at the 5''-position of 4,5-disubstituted aminoglycoside antibiotics (AGAs) to circumvent inactivation by the APH(3',5'') class of aminoglycoside modifying enzymes (AMEs) has been widely reported.  Such modifications, however, impact activity against wild type bacteria and affect target selectivity in unpredictable ways thereby hindering drug development.  We present a systematic survey of modifications to the 5''-position of the 4,5-AGAs and of the related 5- O -furanosyl apramycin derivatives. In the neomycin and the apralog series, all modifications were well-tolerated, but other 4,5-AGAs require the presence of a hydrogen bonding group at the 5''-position for maintenance of high antibacterial activity. Though the 5''-amino modification resulted in comparable activity to the parent compounds, reduced selectivity against the human cytosolic decoding A site renders this modification generally unfavorable in paromomycin, propylamycin, and ribostamycin. Installation of a 5''-formamido group and, to a lesser degree, a 5''-ureido group resulted in comparable activity to the parents without the selectivity cost of the 5''-amino modification. The lessons learned from this work will aid in the design of next-generation AGAs capable of circumventing susceptibility to AMEs while maintaining high antibacterial activity and target selectivity.

Antimicrobial Resistance of Tannin Extract against E. coli Isolates from Sheep

Plants have been long valuable sources of natural materials that have served to preserve human and animal health; as a result, pharmacological purposes have arisen from the use of plant compounds in most countries, according to a World Health Organization report. The present study aimed to assess the antimicrobial resistance of tannin extract against Escherichia coli (E. coli) isolates in sheep. A total of 100 samples from sheep were used to isolate E. coli and treated with tannin extract (90% purity) to investigate the in vitro effect, as compared to some antibiotics (Clindamycin, Cephalexin, Kanamycin, Tetracycline, and Vancomycin). The bacterial samples were cultured in a selective and differential medium, and Gram staining was used to examine them. The biochemical assays were performed to purify and expose these cultures; moreover, the API 20E system and Rapid^TM ONE kits were utilized to confirm the bacterial strain. Based on the findings, 50% of the samples showed a positive result for the presence of E. coli. The well diffusion technique was used to investigate the antibacterial activity to confirm the antibacterial action of tannin extract (from pomegranate peel) in different concentrations against E. coli. The highest zone of inhibition for the bacteria ranged from 12±0.5 to 30.3±0.2 at 50% concentrations, proving that tannins extract was significantly effective against E. coli. The presence of E. coli was detected in 50 % of the samples. The well-diffusion technique was used to evaluate the antimicrobial property of tannin extract through various concentrations with the highest zone of inhibition for the bacteria ranging from 12.5 to 30.30.2 at 50%, demonstrating that tannin extract was significantly effective on E. coli.

Carvacrol Enhances the Antimicrobial Potency of Berberine in Bacillus subtilis

The essential oil carvacrol from oregano displays a wide range of biological activities among which is found the inhibition of efflux pumps. Thus, using carvacrol, the current work undertook the effort to potentiate the antimicrobial activity of berberine, a natural product with limited antimicrobial efficacy due to its efflux. Following the selection of concentrations for the combinatorial treatments, guided by checkerboard microtiter plate assay and growth experiments, ethidium bromide accumulation assay was used to find that 25 μg mL^-1 carvacrol displayed a weak efflux pump inhibitor character in Bacillus subtilis. Scanning electron microscopy images and cellular material leakage assays showed that carvacrol at this concentration neither altered the morphology nor the permeability of the membrane alone but when combined with 75 μg mL^-1 berberine. Among the efflux pumps of different families found in B. subtilis, except for BmrA and Mdr, the increase in the expressional changes was striking, with Blt displaying ~ 4500-fold increase in expression under the combination treatment. Overall, the findings demonstrated that carvacrol potentiated the effect of berberine; however, not only multiple pumps but also different targets may be responsible for the observed activity.

Analysis of multiple bacterial species and antibiotic classes reveals large variation in the association between seasonal antibiotic use and resistance

Understanding how antibiotic use drives resistance is crucial for guiding effective strategies to limit the spread of resistance, but the use-resistance relationship across pathogens and antibiotics remains unclear. We applied sinusoidal models to evaluate the seasonal use-resistance relationship across 3 species (Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae) and 5 antibiotic classes (penicillins, macrolides, quinolones, tetracyclines, and nitrofurans) in Boston, Massachusetts. Outpatient use of all 5 classes and resistance in inpatient and outpatient isolates in 9 of 15 species-antibiotic combinations showed statistically significant amplitudes of seasonality (false discovery rate (FDR) < 0.05). While seasonal peaks in use varied by class, resistance in all 9 species-antibiotic combinations peaked in the winter and spring. The correlations between seasonal use and resistance thus varied widely, with resistance to all antibiotic classes being most positively correlated with use of the winter peaking classes (penicillins and macrolides). These findings challenge the simple model of antibiotic use independently selecting for resistance and suggest that stewardship strategies will not be equally effective across all species and antibiotics. Rather, seasonal selection for resistance across multiple antibiotic classes may be dominated by use of the most highly prescribed antibiotic classes, penicillins and macrolides.

Evaluation of phenotypic and genotypic patterns of aminoglycoside resistance in the Gram-negative bacteria isolates collected from pediatric and general hospitals

The purpose of the current study was to evaluate the phenotypic and genotypic patterns of aminoglycoside resistance among the Gram-negative bacteria (GNB) isolates collected from pediatric and general hospitals in Iran. A total of 836 clinical isolates of GNB were collected from pediatric and general hospitals from January 2018 to the end of December 2019. The identification of bacterial isolates was performed by conventional biochemical tests. Susceptibility to aminoglycosides was evaluated by the disk diffusion method (DDM). The frequency of genes encoding aminoglycoside-modifying enzymes (AMEs) was screened by the PCR method via specific primers. Among all pediatric and general hospitals, the predominant GNB isolates were Acinetobacter spp. (n = 327) and Escherichia coli (n = 144). However, E. coli (n = 20/144; 13.9%) had the highest frequency in clinical samples collected from pediatrics. The DDM results showed that 64.3% of all GNB were resistant to all of the tested aminoglycoside agents. Acinetobacter spp. and Klebsiella pneumoniae with 93.6%, Pseudomonas aeruginosa with 93.4%, and Enterobacter spp. with 86.5% exhibited very high levels of resistance to gentamicin. Amikacin was the most effective antibiotic against E. coli isolates. In total, the results showed that the aac (6')-Ib gene with 59% had the highest frequency among genes encoding AMEs in GNB. The frequency of the surveyed aminoglycoside-modifying enzyme genes among all GNB was found as follows: aph (3')-VIe (48.7%), aadA15 (38.6%), aph (3')-Ia (31.3%), aph (3')-II (14.4%), and aph (6) (2.6%). The obtained data demonstrated that the phenotypic and genotypic aminoglycoside resistance among GNB was quite high and it is possible that the resistance genes may frequently spread among clinical isolates of GNB.

T7 Phage as an Emerging Nanobiomaterial with Genetically Tunable Target Specificity

Bacteriophages, also known as phages, are specific antagonists against bacteria. T7 phage has drawn massive attention in precision medicine owing to its distinctive advantages, such as short replication cycle, ease in displaying peptides and proteins, high stability and cloning efficiency, facile manipulation, and convenient storage. By introducing foreign gene into phage DNA, T7 phage can present foreign peptides or proteins site-specifically on its capsid, enabling it to become a nanoparticle that can be genetically engineered to screen and display a peptide or protein capable of recognizing a specific target with high affinity. This review critically introduces the biomedical use of T7 phage, ranging from the detection of serological biomarkers and bacterial pathogens, recognition of cells or tissues with high affinity, design of gene vectors or vaccines, to targeted therapy of different challenging diseases (e.g., bacterial infection, cancer, neurodegenerative disease, inflammatory disease, and foot-mouth disease). It also discusses perspectives and challenges in exploring T7 phage, including the understanding of its interactions with human body, assembly into scaffolds for tissue regeneration, integration with genome editing, and theranostic use in clinics. As a genetically modifiable biological nanoparticle, T7 phage holds promise as biomedical imaging probes, therapeutic agents, drug and gene carriers, and detection tools.

Co-occurrence of genes encoding carbapenemase, ESBL, pAmpC, and Non-β-Lactam resistance among Klebsiella pneumonia and E. coli clinical isolates in Tunisia

This study aimed to investigate the molecular mechanisms of carbapenem and colistin resistance in K. pneumoniae and E. coli isolates obtained from hospitalized patients in Carthagene International Hospital of Tunis. A total of 25 K. pneumoniae and 2 E. coli clinical isolates with reduced susceptibility to carbapenems were recovered. Susceptibility testing and phenotypic screening tests were carried out. ESBL, AmpC, carbapenemase, and other antibiotic resistance genes were sought by PCR-sequencing. The presence of plasmid-mediated colistin resistance genes (mcr-1-8) was examined by PCR and the nucleotide sequence of the mgrB gene was determined. The analysis of plasmid content was performed by PCR-Based Replicon Typing (PBRT). The clonality of isolates was assessed by PFGE and multilocus sequence typing (MLST). All of the isolates produced carbapenemase activity. They showed a great variation in the distribution of ESBL, AmpC, carbapenemase, and other plasmid-mediated resistance determinants. K. pneumoniae isolates carried bla_NDM-1 (n=11), bla_OXA-48 (n=11), bla_NDM-1 + bla_OXA-48 (n=1), bla_NDM-1 + bla_VIM-1 (n=1), bla_OXA-204 (n=1), along with bla_CTX-M , bla_OXA , bla_TEM , bla_CMY , bla_DHA and bla_SHV genes variants on conjugative plasmid of IncL/M, IncR, IncFII_K , IncFIB, and IncHI1 types. Three sequence types ST101, ST307, and ST15 were identified. The mgrB alteration g109a (G37S) was detected in a single colistin-resistant, NDM-1 and OXA-48-coproducing K. pneumoniae isolate. The two E. coli isolates belonged to ST95, co-produced NDM-1 and CTX-M-15, and harbored plasmid of IncFII and IncFIB types. To our knowledge, this is the first report in Tunisia of NDM-1, OXA-48, and CTX-M-15 coexistence in colistin-resistant K. pneumoniae ST15.

Pelzer B, Khodamoradi Y, Vehreschild MJGT. The role of the human gut microbiota in colonization and infection with multidrug-resistant bacteria

About 100 years ago, the first antibiotic drug was introduced into health care. Since then, antibiotics have made an outstanding impact on human medicine. However, our society increasingly suffers from collateral damage exerted by these highly effective drugs. The rise of resistant pathogen strains, combined with a reduction of microbiota diversity upon antibiotic treatment, has become a significant obstacle in the fight against invasive infections worldwide.Alternative and complementary strategies to classical "Fleming antibiotics" comprise microbiota-based treatments such as fecal microbiota transfer and administration of probiotics, live-biotherapeutics, prebiotics, and postbiotics. Other promising interventions, whose efficacy may also be influenced by the human microbiota, are phages and vaccines. They will facilitate antimicrobial stewardship, to date the only globally applied antibiotic resistance mitigation strategy.In this review, we present the available evidence on these nontraditional interventions, highlight their interaction with the human microbiota, and discuss their clinical applicability.

A Bayesian approach to modeling antimicrobial multidrug resistance

Multidrug resistance (MDR) has been a significant threat to public health and effective treatment of bacterial infections. Current identification of MDR is primarily based upon the large proportions of isolates resistant to multiple antibiotics simultaneously, and therefore is a belated evaluation. For bacteria with MDR, we expect to see strong correlations in both the quantitative minimum inhibitory concentration (MIC) and the binary susceptibility as classified by the pre-determined breakpoints. Being able to detect correlations from these two perspectives allows us to find multidrug resistant bacteria proactively. In this paper, we provide a Bayesian framework that estimates the resistance level jointly for antibiotics belonging to different classes with a Gaussian mixture model, where the correlation in the latent MIC can be inferred from the Gaussian parameters and the correlation in binary susceptibility can be inferred from the mixing weights. By augmenting the laboratory measurement with the latent MIC variable to account for the censored data, and by adopting the latent class variable to represent the MIC components, our model was shown to be accurate and robust compared with the current assessment of correlations. Applying the model to Salmonella heidelberg samples isolated from human participants in National Antimicrobial Resistance Monitoring System (NARMS) provides us with signs of joint resistance to Amoxicillin-clavulanic acid & Cephalothin and joint resistance to Ampicillin & Cephalothin. Large correlations estimated from our model could serve as a timely tool for early detection of MDR, and hence a signal for clinical intervention.

Discovery of a novel class of small-molecule antibacterial agents against Staphylococcus aureus

Background: With constantly increasing resistance against the known antibiotics, the search for novel antibacterial compounds is a challenge. The number of synthetic antibacterial agents is limited. Materials & methods: We discovered novel small-molecule antibacterial agents that are accessible via a simple two-step procedure. The evaluation against Staphylococcus aureus showed antibacterial effects depending on the substituent positioning at the residues of the molecular scaffold. Additionally, we investigated the potential of the compounds to increase the antibacterial activity of tetracycline. Results: The most effective antibacterial compounds possessed a 3-methoxy function at an aromatic residue. In combination with tetracycline, we found a strong effect for a few compounds in boosting the antibacterial activity, so the first promising lead compounds with dual activities could be identified.

20% ALA-PDT pretreated by fire needle in patients with dissecting cellulitis of the scalp: An interim analysis

BACKGROUND

Dissecting cellulitis of the scalp (DCS) is a rare but distinctive, chronic suppurative condition, and the treatment is a therapeutic challenge. Recently, treatment of DCS with 5-aminolaevulinic acid photodynamic therapy (ALA-PDT) has been considered as a potential option.

OBJECTIVE

To evaluate the efficacy and safety of 20% ALA-PDT pretreated by fire needle in the treatment of DCS.

MATERIALS AND METHODS

Topical 20% ALA-PDT with fire needle intervention as a pretreatment, was applied to six patients with DCS. All patients completed three sessions treatment at an interval of ten days. They were assessed for the efficacy at the baseline and on ten days after each treatment. According to the reduction of lesions and the improvements of patients' symptoms after each session, the objective assessment of therapeutic effect was divided into four grades. The adverse effects were recorded.

RESULTS

A total of six male patients were enrolled in our study. After three sessions of ALA-PDT, among them, three patients recovered, two patients achieved significant improvement and one patient achieved partial response.Patient 4 (Pt.4) relapsed at 6-month follow-up. Pt.1 and Pt.6. maintained complete response after one year follow-up. We also found that the clearance rate of the popular/nodular and cyst/abscess was much higher than sinus.

CONCLUSION

20% ALA-PDT pretreated by fire needle could be an effective, minimally-invasive, safe method for DCS patients. Lesion in the early stages have a better response than sinus.

Novel Micro-Nano Optoelectronic Biosensor for Label-Free Real-Time Biofilm Monitoring

According to the World Health Organization forecasts, AntiMicrobial Resistance (AMR) is expected to become one of the leading causes of death worldwide in the following decades. The rising danger of AMR is caused by the overuse of antibiotics, which are becoming ineffective against many pathogens, particularly in the presence of bacterial biofilms. In this context, non-destructive label-free techniques for the real-time study of the biofilm generation and maturation, together with the analysis of the efficiency of antibiotics, are in high demand. Here, we propose the design of a novel optoelectronic device based on a dual array of interdigitated micro- and nanoelectrodes in parallel, aiming at monitoring the bacterial biofilm evolution by using optical and electrical measurements. The optical response given by the nanostructure, based on the Guided Mode Resonance effect with a Q-factor of about 400 and normalized resonance amplitude of about 0.8, allows high spatial resolution for the analysis of the interaction between planktonic bacteria distributed in small colonies and their role in the biofilm generation, calculating a resonance wavelength shift variation of 0.9 nm in the presence of bacteria on the surface, while the electrical response with both micro- and nanoelectrodes is necessary for the study of the metabolic state of the bacteria to reveal the efficacy of antibiotics for the destruction of the biofilm, measuring a current change of 330 nA when a 15 µm thick biofilm is destroyed with respect to the absence of biofilm.

Virulence Genes Profile and Antimicrobial Susceptibility of Community-Acquired Bacterial Urinary Tract Infections in a Brazilian Hospital

Urinary tract infections (UTI) are one of the most common diseases worldwide and Escherichia coli is the most common causative bacteria. Empirical treatment is challenging due to antimicrobial or multidrug-resistance. The aims of this study were to determine the uropathogens and their antimicrobial susceptibility profile, as well as to identify the phylogroups and virulence genes of E. coli strains, associated with community-acquired UTI in outpatients admitted at a Brazilian Hospital in southeast Brazil. In total, 47 bacterial strains were isolated from 47 patients, 44 women and 2 men (no gender record from one patient). The age of the patients whose urine culture were positive varied from 0 (less than one month) to 104 years. Most of the isolates were E. coli (41/47), followed by Klebsiella pneumoniae (2/47), Klebsiella variicola/Klebsiella aerogenes (1/47), Pseudomonas aeruginosa (1/47), Proteus mirabilis (1/47), and Citrobacter koseri (1/47). Most E. coli strains were classified as phylogroup B2 (15/41 = 36.59%) and B1 (12/41 = 29.27%) and the most common virulence genes among E. coli strains were fimH (31/41 = 75.61%), iutA (21/41 = 51.22%), and tratT (16/41 = 39.02%). Among the E. coli strains, 59% were multidrug-resistance and strains that were ampicillin, sulfamethoxazole/trimethoprim, or tetracycline-resistant exhibited more chance to be multidrug-resistance, with an odds ratio of 100.00 [95% confidence interval (CI) 9.44-1059.26], 22.50 (95% CI 3.95-128.30), and 12.83 (95% CI 2.68-61.45), respectively. Our results showed that E. coli was the main etiological agent identified and demonstrated high frequency of multidrug-resistance and virulence factors in bacterial strains isolated from UTIs.

Resistance genes and extracellular proteins relieve antibiotic stress on the anammox process

The anaerobic ammonium oxidation (anammox) process is regarded as a promising approach to treat antibiotic-containing wastewater. Therefore, it is urgent to elucidate the effects of various antibiotics on the anammox process. Moreover, the mechanism of extracellular polymeric substance (EPS) as protective barriers to relieve antibiotic stress remain unclear. Therefore, the single and combined effects of erythromycin (ETC) and sulfamethoxazole (SMZ), and interactions between EPS and antibiotics were investigated in this study. Based on a 228-day continuous flow experiment, high concentrations of ETC and SMZ had significant inhibitory effects on the nitrogen removal performance of the anammox process, with the abundances of corresponding antibiotic resistance genes (ARGs) increasing. In addition, the combined inhibitory effect of the two antibiotics on the anammox process was more significant and longer-lasting than that of the single. However, the anammox process was able to quickly recover from deterioration. The tolerance of anammox granules to the stress of low-concentration antibiotics was probably attributed to the increase in ARGs and secretion of EPS. Molecular docking simulation results showed that proteins in EPS could directly bind with SMZ and ETC at the sites of GLU-307, HYS-191, ASP-318 and THR-32, respectively. These findings improved our understanding of various antibiotic effects on the anammox process and the interaction mechanism between antibiotics and proteins in EPS.

A prospective study of the effect of fire micro-needling plus 5% topical ALA-PDT for the treatment of dissecting cellulitis of the scalp

BACKGROUND

Different therapies have been used for dissecting cellulitis of the scalp (DCS) with poor results. Topical 5-aminolaevulinic acid photodynamic therapy (ALA-PDT) is effective for many inflammatory skin diseases.

OBJECTIVES

To evaluate the efficacy and safety of fire micro-needling plus 5% ALA-PDT on DCS.

METHODS

Forty-two male DCS patients were enrolled and treated by four sessions of fire micro-needling plus 5% ALA-PDT (occlusion time: 3 h, 100 mW/cm² for 20-32 min, 633 ± 10 nm LED) with an interval of 1-2 weeks. The reduction of lesions was evaluated at each follow-up visit. The patients` symptoms were evaluated by Dermatology Life Quality Index (DLQI). All of the side effects were recorded.

RESULTS

Forty-one DCS patients finished the treatments and the marked effective rate (MER) reached 65.85%. Ten patients (24.39%) were cured and 17 patients (41.46%) achieved excellent improvement. The median of lesion numbers decreased significantly from 25 to 7 (p < 0.001) with DLQI from 13 to 2 (p < 0.001). Although all the ten cured patients had a relapse during the 12-month follow-up, 5/10 patients had a remission of more than 6 months. All the patients tolerated PDT well with mild adverse effects.

CONCLUSIONS

Fire micro-needling plus 5% ALA-PDT is effective for Chinese male DCS patients without the need to take systemic drugs.

Price equation captures the role of drug interactions and collateral effects in the evolution of multidrug resistance

Bacterial adaptation to antibiotic combinations depends on the joint inhibitory effects of the two drugs (drug interaction [DI]) and how resistance to one drug impacts resistance to the other (collateral effects [CE]). Here we model these evolutionary dynamics on two-dimensional phenotype spaces that leverage scaling relations between the drug-response surfaces of drug-sensitive (ancestral) and drug-resistant (mutant) populations. We show that evolved resistance to the component drugs - and in turn, the adaptation of growth rate - is governed by a Price equation whose covariance terms encode geometric features of both the two-drug-response surface (DI) in ancestral cells and the correlations between resistance levels to those drugs (CE). Within this framework, mean evolutionary trajectories reduce to a type of weighted gradient dynamics, with the drug interaction dictating the shape of the underlying landscape and the collateral effects constraining the motion on those landscapes. We also demonstrate how constraints on available mutational pathways can be incorporated into the framework, adding a third key driver of evolution. Our results clarify the complex relationship between drug interactions and collateral effects in multidrug environments and illustrate how specific dosage combinations can shift the weighting of these two effects, leading to different and temporally explicit selective outcomes.

Structure-activity relationship study of amphipathic antimicrobial peptides using helix-destabilizing sarcosine

Antimicrobial peptides (AMPs) are potential therapeutic agents against bacteria. We recently showed that a rationally designed AMP, termed Stripe, with an amphipathic distribution of native cationic and hydrophobic amino acids on its helical structure exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria with negligible hemolytic activity and cytotoxicity. In this study, the structure-activity relationship of Stripe was elucidated by designing a series of antimicrobial peptides whereby amino acid residues of Stripe were exchanged with helix-destabilizing sarcosine residues. Stripe 1-5 peptides with hydrophobic amino acids substituted with sarcosine were predominantly unstructured and showed no antimicrobial activity, except against Escherichia coli (E. coli) (DH5α) cells. The activity against E. coli (DH5α) cells and the helicity of Stripe 1-5 peptides decreased concomitantly as the number of sarcosine residue substitutions increased. Stripe 1-5 peptides showed no hemolytic activity or cytotoxicity. The results indicate that sarcosine substitutions provide an approach to study the structure-activity relationship of helical AMPs, and the helicity of Stripe is an important feature defining its activity.

Gut resistome of preschool children after prolonged mass azithromycin distribution: a cluster-randomized trial

We evaluated the gut resistome of children from communities treated with 10 twice-yearly azithromycin distributions. While the macrolide resistance remained higher in the azithromycin arm, the selection of non-macrolide resistance observed at earlier time points did not persist. Longitudinal resistance monitoring should be a critical component of mass distribution programs.

Genomic surveillance of antimicrobial resistance shows cattle and poultry are a moderate source of multi-drug resistant non-typhoidal Salmonella in Mexico

Multi-drug resistant (MDR) non-typhoidal Salmonella (NTS) is a public health concern globally. This study reports the phenotypic and genotypic antimicrobial resistance (AMR) profiles of NTS isolates from bovine lymph nodes (n = 48) and ground beef (n = 29). Furthermore, we compared genotypic AMR data of our isolates with those of publicly available NTS genomes from Mexico (n = 2400). The probability of finding MDR isolates was higher in ground beef than in lymph nodes:χ2 = 12.0, P = 0.0005. The most common resistant phenotypes involved tetracycline (40.3%), carbenicillin (26.0%), amoxicillin-clavulanic acid (20.8%), chloramphenicol (19.5%) and trimethoprim-sulfamethoxazole (16.9%), while more than 55% of the isolates showed decreased susceptibility to ciprofloxacin and 26% were MDR. Conversely, resistance to cephalosporins and carbapenems was infrequent (0-9%). MDR phenotypes were strongly associated with NTS serovar (χ2 = 24.5, P<0.0001), with Typhimurium accounting for 40% of MDR strains. Most of these (9/10), carried Salmonella genomic island 1, which harbors a class-1 integron with multiple AMR genes (aadA2, blaCARB-2, floR, sul1, tetG) that confer a penta-resistant phenotype. MDR phenotypes were also associated with mutations in the ramR gene (χ2 = 17.7, P<0.0001). Among public NTS isolates from Mexico, those from cattle and poultry had the highest proportion of MDR genotypes. Our results suggest that attaining significant improvements in AMR meat safety requires the identification and removal (or treatment) of product harboring MDR NTS, instead of screening for Salmonella spp. or for isolates showing resistance to individual antibiotics. In that sense, massive integration of whole genome sequencing (WGS) technologies in AMR surveillance provides the shortest path to accomplish these goals.

Antimicrobial Susceptibility among Pathogens Isolated in Early- versus Late-Onset Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is associated with increased hospital stay and high morbidity and mortality in critically ill patients. The aims of this study were to (i) determine the incidence of multidrug-resistant (MDR) pathogens in the first episodes of VAP and to assess potential differences in bacterial profiles of subjects with early- versus late-onset VAP. This was a retrospective cohort study over a period of 18 months including all patients who had a first episode of VAP confirmed by positive bacterial culture. Subjects were distributed into two groups according to the number of intubation days: early-onset VAP (<5 days) or late-onset VAP (≥5 days). The primary endpoint was the nature of causative pathogens and their resistance profiles. Sixty patients were included, 29 men and 31 women, with an average age of 38 ± 16 years. The IGS 2 at admission was 40.5 [32–44] and APACHE was 19 [15–22]. Monomicrobial infections were diagnosed in 77% of patients (n = 46). The most frequently isolated bacteria were A. baumannii, 53% (n = 32); P. aeruginosa in 37% (n = 22); Enterobacterales in 28% (n = 17) and S. aureus in 5% (n = 3). Ninety-seven percent of the bacteria were MDR. The VAP group comprised 36 (60%) episodes of early-onset VAP and 24 (40%) episodes of late-onset VAP. There was no significant difference in the distribution of the bacterial isolates, nor in terms of antibacterial resistances between early- and late-onset VAPs. Our data support recent observations that there is no microbiological difference in the prevalence of potential MDR pathogens or in their resistance profiles associated with early- versus late-onset VAPs, especially in countries with high rates of MDR bacteria.

Analysis of Multidrug Resistance in Staphylococcus aureus with a Machine Learning-Generated Antibiogram

Multidrug resistance (MDR) surveillance consists of reporting MDR prevalence and MDR phenotypes. Detailed knowledge of the specific associations underlying MDR patterns can allow antimicrobial stewardship programs to accurately identify clinically relevant resistance patterns. We applied machine learning and graphical networks to quantify and visualize associations between resistance traits in a set of 1,091 Staphylococcus aureus isolates collected from one New York hospital between 2008 and 2018. Antimicrobial susceptibility testing was performed using reference broth microdilution. The isolates were analyzed by year, methicillin susceptibility, and infection site. Association mining was used to identify resistance patterns that consisted of two or more individual antimicrobial resistance (AMR) traits and quantify the association among the individual resistance traits in each pattern. The resistance patterns captured the majority of the most common MDR phenotypes and reflected previously identified pairwise relationships between AMR traits in S. aureus Associations between β-lactams and other antimicrobial classes (macrolides, lincosamides, and fluoroquinolones) were common, although the strength of the association among these antimicrobial classes varied by infection site and by methicillin susceptibility. Association mining identified associations between clinically important AMR traits, which could be further investigated for evidence of resistance coselection. For example, in skin and skin structure infections, clindamycin and tetracycline resistance occurred together 1.5 times more often than would be expected if they were independent from one another. Association mining efficiently discovered and quantified associations among resistance traits, allowing these associations to be compared between relevant subsets of isolates to identify and track clinically relevant MDR.

Shotgun metagenomics reveals a heterogeneous prokaryotic community and a wide array of antibiotic resistance genes in mangrove sediment

Saline tolerant mangrove forests partake in vital biogeochemical cycles. However, they are endangered due to deforestation as a result of urbanization. In this study, we have carried out a metagenomic snapshot of the mangrove ecosystem from five countries to assess its taxonomic, functional and antibiotic resistome structure. Chao1 alpha diversity varied significantly (P < 0.001) between the countries (Brazil, Saudi Arabia, China, India and Malaysia). All datasets were composed of 33 phyla dominated by eight major phyla covering >90% relative abundance. Comparative analysis of mangrove with terrestrial and marine ecosystems revealed the strongest heterogeneity in the mangrove microbial community. We also observed that the mangrove community shared similarities to both the terrestrial and marine microbiome, forming a link between the two contrasting ecosystems. The antibiotic resistant genes (ARG) resistome was comprised of nineteen level 3 classifications dominated by multidrug resistance efflux pumps (46.7 ± 4.3%) and BlaR1 family regulatory sensor-transducer disambiguation (25.2 ± 4.8%). ARG relative abundance was significantly higher in Asian countries and in human intervention datasets at a global scale. Our study shows that the mangrove microbial community and its antibiotic resistance are affected by geography as well as human intervention and are unique to the mangrove ecosystem. Understanding changes in the mangrove microbiome and its ARG is significant for sustainable development and public health.