Antibiotic-resistant Gram-negative Bacteria Research Articles

Distribution of antibiotic resistant bacteria and genes in sewage and surrounding environment of Tórshavn, Faroe Islands

Several studies have investigated the effects of swimming in sewage-polluted recreational beach water, highlighting the associated health hazards. To mitigate potential pathogen transmission, it is imperative that the polluted water is released away from recreational waters and foreshores, where children tend to play. At present, domestic sewage in the Faroe Islands solely undergoes primary wastewater treatment within primary settling tanks before being discharged into the ocean. Effluents are a major anthropogenic source of antibiotic resistance genes and antibiotic resistant bacteria, which are released into the environment. The aim of this study was to investigate antibiotic resistant Gram-negative bacteria and antibiotic resistance genes in influents and effluents of wastewater subjected solely to primary treatment, along with their release into the environment during both summer and winter. Water samples were collected from influents and effluents as well as with increasing distance away from the wastewater outlet and from nearby tidepools. Samples were cultured on MacConkey agar with four different antibiotics for detection of antibiotic-resistant bacteria and antibiotic resistance genes were quantified by droplet digital PCR. All multi-drug resistant bacteria were identified using the API 20E kit. We observed an overall decrease of the abundance of Gram-negative bacteria from the effluents compared to influents, however, we observed the opposite trend in the antibiotic resistance genes. Antibiotic resistant bacteria and antibiotic resistance genes in addition to multi-drug resistant bacteria were found in the surrounding oceanic and several terrestrial tidepool samples. Of the multi-drug resistant bacteria, we found, e.g., Escherichia coli, P. aeruginosa, and A. hydrophila species, which can be pathogenic, potentially causing an infection if encountering a host. These results indicate a relatively wide pollution range of the effluents from the septic tank and treated sewage released into the environment, posing a potential hazard for both humans and wildlife.

Polymyxin B nonapeptide potentiates the eradication of Gram-negative bacterial persisters.

The significance of our study lies in addressing the problem of antibiotic-resistant Gram-negative bacteria, which continue to be a global cause of mortality associated with bacterial infections. Therefore, identifying innovative therapeutic approaches is an urgent need. Recent research has highlighted the potential of selective antibacterials like polymyxins, which specifically target the lipopolysaccharides of Gram-negative bacteria. However, the clinical use of polymyxins is limited by their severe cytotoxicity. This study unveils the effectiveness of polymyxin B nonapeptide (PMBN) in significantly enhancing the eradication of persister cells in Gram-negative bacteria. Although PMBN itself does not exhibit antibacterial activity or cytotoxicity, it remarkably reduces persister cells during the treatment of antibiotics. Moreover, combining PMBN with other antibiotics reduces the emergence of resistant mutants. Our research emphasizes the utility of PMBN as a novel potentiator to decrease persister cells during antibiotic treatments for Gram-negative bacteria.

Redundant essentiality of AsmA-like proteins in Pseudomonas aeruginosa.

Given the importance of the outer membrane (OM) for viability and antibiotic resistance in Gram-negative bacteria, in the last decades, several studies have focused on the characterization of the systems involved in OM biogenesis, which have also been explored as targets for antibacterial drug development. However, the mechanism mediating translocation of glycerophospholipids (GPLs) to the OM remained unknown until recent studies provided evidence that AsmA-like proteins could be responsible for this process. Here, we demonstrate for the first time that AsmA-like proteins are essential and redundant for growth and OM integrity in a Gram-negative bacterium other than the model organism Escherichia coli and demonstrate that the human pathogen Pseudomonas aeruginosa has an additional essential AsmA-like protein that is not present in E. coli, thus expanding the range of AsmA-like proteins that play key functions in Gram-negative bacteria.

High-throughput computational screening for identification of potential hits against bacterial Acriflavine resistance protein B (AcrB) efflux pump

Antibiotic resistance is a pressing global health challenge, driven in part by the remarkable efflux capabilities of efflux pump in AcrB (Acriflavine Resistance Protein B) protein in Gram-negative bacteria. In this study, a multi-approached computational screening strategy encompassing molecular docking, In silico absorption, distribution, metabolism, excretion and toxicity (ADMET) analysis, druglikeness assessment, molecular dynamics simulations and density functional theory studies was employed to identify novel hits capable of acting against AcrB-mediated antibiotic resistance. Ligand library was acquired from the COCONUT database. Performed computational analyses unveiled four promising hit molecules (CNP0298667, CNP0399927, CNP0321542 and CNP0269513). Notably, CNP0298667 exhibited the highest negative binding affinity of −11.5 kcal/mol, indicating a possibility of strong potential to disrupt AcrB function. Importantly, all four hits met stringent druglikeness criteria and demonstrated favorable in silico ADMET profiles, underscoring their potential for further development. MD simulations over 100 ns revealed that the CNP0321542-4DX5 and CNP0269513-4DX5 complexes formed robust and stable interactions with the AcrB efflux pump. The identified hits represent a promising starting point for the design and optimization of novel therapeutics aimed at combating AcrB-mediated antibiotic resistance in Gram-negative bacteria. Communicated by Ramaswamy H. Sarma

Susceptibility analysis of various bacteria towards colistin and other antibiotics in clinical isolates

This study aimed to determine the susceptibility of Gram-negative bacilli isolated from various clinical samples of patients admitted to ICUs of hospitals in Telangana region against colistin and compared with other antibiotics. In the present study clinical pathogen isolates were used for the susceptibility test. A total of 1852 consecutive Gram-negative isolates were tested for Colistin susceptibility. All the bacterial isolates of (e.g., , ), and were included. All Colistin resistant isolates were processed to detect the minimum inhibitory concentration (MIC) of antibiotics by the broth micro-dilution method. It was observed that in . and the susceptibility was quite significant whereas it was not much significant for other species of bacteria studied namely, , , , and . . and resistance indicated that there is an argent need to get the current situation under control by implementing appropriate measures to slow down the progression of antibiotic resistance in gram-negative bacteria in Telangana. and showed significant resistance to Colistin compared with other antibiotics than other gram-negative bacilli isolated from various clinical samples. There is a shortage of clinical data available in South India regarding the prevalence of colistin resistance. This study is one of the few studies that indicate the current scenario of resistance of gram-negative bacteria in this particular area.

Effect of Gram-positive bacteria on antibiotic resistance in Gram-negative bacteria

Antibiotics are one of the most common treatments for bacterial infections, but the emergence of antibiotic resistance is a major threat to the control of infectious diseases. Many factors contribute to the development of antibiotic resistance. One is bacterial conjugation from Gram-positive to Gram-negative bacteria where there is a transfer of resistance genes from Gram-positive to Gram-negative bacteria that could increase antibiotic resistance in the latter. In light of these observations, we decided to test whether Gram-negative bacteria that came into contact with Gram-positive bacteria had a higher resistance to the antimicrobial properties of spices than Gram-negative bacteria that did not come into contact with Gram-positive bacteria. We hypothesized that Gram-negative bacteria that had been exposed to Gram-positive bacteria would be more resistant to antibiotics than unexposed Gram-negative bacteria. To test our hypothesis, we cultured and subcultured lettuce (Gram-negative) bacteria and forearm (Gram-positive) bacteria, as well as lettuce bacteria that encountered forearm bacteria, on agar plates using powdered ginger, which has previously been shown to have antimicrobial properties to assess antibiotic resistance. We found that lettuce bacteria that encountered forearm bacteria were indeed more resistant to ginger since they showed more growth than lettuce bacteria. These results indicate that Gram-positive bacteria may transfer their resistance genes to Gram-negative bacteria, resulting in increased antibiotic resistance. If thousands of Gram-positive bacteria become antibiotic-resistant and pass those genes to Gram-negative bacteria found in the human body, it can make bacterial infections more difficult to treat.

Prevalence of extended-spectrum beta-lactamases producing isolates obtained from patients of pediatric critical care unit in a tertiary care hospital

Background: Over the past decades, antibiotic-resistant Gram-negative bacteria commonly Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae have increased significantly. These microorganisms have great clinical importance because they increase hospital stay of the patients in the intensive care unit (ICU) leading to high morbidity and mortality. Because of their role in increasing morbidity and mortality, this study was performed to isolate extended-spectrum beta-lactamase (ESBL) producing Gram-negative bacilli screened by phenotypical method and further projected into molecular characterization by polymerase chain reaction. Aims and Objectives: The aims and objectives are to isolate the Gram-negative multidrug-resistant strains from clinically suspected bacterial infections in patients of neonatal, sick newborn, and pediatric ICU and to study antibiotic sensitivity pattern of isolated Gram-negative multidrug-resistant strains with special reference to molecular characterization. Materials and Methods: A total of 100 Gram-negative bacilli were isolated. Screening of ESBL positivity was done by double-disk synergy test (combined disc test method). Their antibiogram profile was interpreted. With the use of designed primers, 26 ESBL isolates each of E. coli and Klebsiella spp. were processed for molecular analysis of beta-lactamase family genes TEM and CTX-M. Results: Within the 100 samples, majority of the isolates (45%) were Klebsiella spp. and 40% was E. coli isolates. Highest ESBL-producing organisms were observed within E. coli (65%). Prevalence bla-TEM gene was highest followed by bla-CTX-M. These ESBL-producing organisms were found to be resistant to multiple classes of antibiotics. With extensive ESBL surveillance and proper usage of antibiotics, this threatening rise of antibiotic resistance can be mitigated. Conclusion: Gram-negative isolates showed high resistance to commonly used antibiotics. Significant proportions of them were MDR strains. Such high antibiotic resistance is associated with significant morbidity and mortality among pediatric population. MDR along with possession of ESBL associated resistance genes among Gram-negative bacilli pose a serious problem in therapeutic management of patients. Our study signifies that there is a high probability of Gram- negative bacilli to be multi-drug resistant and ESBL positive and earliest detection of such cases should be made.

Synthesis, antibacterial and antimonooxidase activity of 4-(2-methyl-1,3-oxazol-5-yl)benzenesulfonamide

A new method for obtaining 4-(2-methyl-1,3-oxazol-5-yl)benzenesulfonamide an antiglaucomatous drug candidate oxazopt was developed using a diazotization reaction. A combined potentiated effect of the antimicrobial action of carbapenems (meropenem) and aminoglycosides (gentamicin) against antibiotic-resistant gram-positive bacteria Enterococcus faecium, Enterococcus faecalis and gram-negative bacteria Escherichia coli and antimonooxidase effect in vitro was revealed for this compound.

Synergistic antibacterial effects of exopolysaccharides/nickel-nanoparticles composites against multidrug-resistant bacteria

The need for an alternative treatment to fight infectious diseases caused by antibiotic-resistant bacteria is increasing. A possible way to overcome bacterial resistance to antibiotics is by reintroducing commonly used antibiotics with a sensitizer capable of enhancing their antimicrobial effect in resistant bacteria. Here, we use a composite composed of exopolysaccharide capped-NiO NPs, with antimicrobial effects against antibiotic-resistant Gram-positive and Gram-negative bacteria. It potentiated the antimicrobial effects of four different antibiotics (ampicillin, kanamycin, chloramphenicol, and ciprofloxacin) at lower concentrations than their minimal inhibitory concentrations. We observed that the Ni-composite synergistically enhanced, fourfold, the antibacterial effect of kanamycin and chloramphenicol against multidrug-resistant Staphylococcus aureus and Pseudomonas aeruginosa, as well as ampicillin against multidrug-resistant Staphylococcus aureus, and ciprofloxacin against multidrug-resistant Pseudomonas aeruginosa by eightfold. We also found that Ni-composite could not inhibit biofilm synthesis on the tested bacterial strains. Our results demonstrated the possibility of using metal nanoparticles, like NiO, as a sensitizer to overcome bacterial antibiotic resistance.

Prevalence of antibiotic-resistant gram-negative bacteria among patients with urinary tract infection at a facility in Ado Ekiti, Ekiti-State, Nigeria

Urinary Tract Infections (UTIs) constitute a huge public health burden especially in developing countries. This study was carried out to determine the current incidence of antibiotic resistance among Gram-negative bacteria recovered from urine of patients with UTI. This study used a cohort study design wherein one hundred and twenty one (121) mid-stream urine samples were collected and cultured onto sterile Cysteine Lactose Electrolyte Deficient medium (CLED) and MacConkey agar plates. All bacteria recovered were tested for resistance to the selected antibiotics as follows: ceftazidime (30 μg), ceftriaxone (30 μg), gentamicin (1 0μg), ampicillin (10 μg), meropenem (10 μg), ertapenem (10 μg), tetracycline (30 μg), norfloxacin (10 μg) and pefloxacin (5 μg). Twenty (20) isolates were chosen for detection of extended spectrum beta-lactamase producers using the double disk synergy test (DDST). All the bacteria were tested for biofilm production and haemolysis. Among the one hundred and twenty-one (121) mid-stream urine samples collected from patients, forty-six (46) samples grew significant bacteria. The bacteria recovered were Klebsiella pneumonia17 (37.0%), Klebsiella oxytoca 2 (4.3%), Escherichia coli (32.6%) and Proteus mirabilis (26.0%). Overall, the bacteria showed the highest resistance to pefloxacin (97.8%) and least resistance to meropenem (34.7%). The bacteria also showed high multiple resistance. All the bacteria subjected to DDST were confirmed as extended-spectrum beta-lactamase ESBL producers. Forty (43.6%) bacteria were designated as strong biofilm producers while 17.4 % bacteria showed hemolysis. The findings obtained in this study have ramifications for clinical management of UTI and public health public health in general. There should be strict enforcement of antibiotic stewardship.

Revolutionizing Gram-negative bacteria detection: FLIM and multicolor imaging based selective interaction study using colistin passivated carbon dots

The rising prevalence of antibiotic-resistant Gram-negative bacteria presents a major challenge for healthcare and requires the development of new and effective detection techniques. In this study, we present a novel and simple method for the selective detection of Gram-negative bacteria using multi-emissive colistin-passivated carbon dots (m-CCD) based on Fluorescence Lifetime (FLT) response and bioimaging. The m-CCD was synthesized using a one-step microwave-assisted hydrothermal process, and its interaction with Gram-negative bacteria was studied using Fluorescence Lifetime Imaging Microscopy (FLIM) and automated Confocal Laser Scanning Microscopy (CLSM). The investigations revealed a notable reduction in the FLT of m-CCD-treated Gram-negative bacteria (average lifetime of m-CCD, (τavg) m-CCD is 3.91 ns and m-CCD treated Gram-negative bacteria, (τavg) m-CCD-bac is 1.57 ns), demonstrating the selective interaction between them. Furthermore, the CLSM data revealed high specificity of m-CCD for Gram-negative bacteria, even in polymicrobial samples. Importantly, we also demonstrate that this method can quantify Escherichia coli (E. coli) cells with two linear ranges such as 3.40 × 105 – 9.80 × 105 CFU mL−1 and 6.90 × 107–4.14 × 108 CFU mL−1 in standard culture and real samples such as tap water and human urine with a limit of detection ∼ 3.68–4.89 × 104 CFU mL−1. This straightforward method has great potential for the rapid and selective detection of Gram-negative bacteria, paving the way for early diagnosis and treatment of bacterial infections.

A role for the Gram-negative outer membrane in bacterial shape determination

The cell envelope of Gram-negative bacteria consists of three distinct layers: the cytoplasmic membrane, a cell wall made of peptidoglycan (PG), and an asymmetric outer membrane (OM) composed of phospholipid in the inner leaflet and lipopolysaccharide (LPS) glycolipid in the outer leaflet. The PG layer has long been thought to be the major structural component of the envelope protecting cells from osmotic lysis and providing them with their characteristic shape. In recent years, the OM has also been shown to be a load-bearing layer of the cell surface that fortifies cells against internal turgor pressure. However, whether the OM also plays a role in morphogenesis has remained unclear. Here, we report that changes in LPS synthesis or modification predicted to strengthen the OM can suppress the growth and shape defects of Escherichia coli mutants with reduced activity in a conserved PG synthesis machine called the Rod complex (elongasome) that is responsible for cell elongation and shape determination. Evidence is presented that OM fortification in the shape mutants restores the ability of MreB cytoskeletal filaments to properly orient the synthesis of new cell wall material by the Rod complex. Our results are therefore consistent with a role for the OM in the propagation of rod shape during growth in addition to its well-known function as a diffusion barrier promoting the intrinsic antibiotic resistance of Gram-negative bacteria.

Precision Dosing of Antibiotics and Potentiators by Hypoxia-Responsive Nanoparticles for Overcoming Antibiotic Resistance in Gram-Negative Bacteria.

The stalling development of antibiotics, especially against intrinsically resistant Gram-negative pathogens associated with outer membranes, leads to an emerging antibiotic crisis across the globe. To breathe life into existing drugs, we herein report a hypoxia-responsive nanoparticle (NP) that encapsulates a hydrophobic antibiotic, rifampicin, and a cationic potentiator, polysulfonium. The simultaneous release of antibiotics and potentiators can be promoted and inhibited in response to the severity of bacterial-induced hypoxia, leading to antimicrobial dosing in a precision manner. Under the synergism of polysulfoniums with membrane-disruption capability, the NPs can intensively decrease the antibiotic dose by up to 66-95% in eliminating planktonic Gram-negative P. aeruginosa bacteria and achieve an 8-log reduction of bacteria in mature biofilms at rifampicin MIC. The NP formulation demonstrates that precision dosing of antibiotics and potentiators regulated by hypoxia provides a promising strategy to maximize efficacy and minimize toxicity in treating Gram-negative bacterial infection.

Prevalence of antibiotic-resistant Gram-negative bacteria having extended-spectrum β-lactamase phenotypes in polluted irrigation-purpose wastewaters from Indian agro-ecosystems.

Antibiotic resistance in bacteria has emerged as a serious public health threat worldwide. Aquatic environments including irrigation-purpose wastewaters facilitate the emergence and transmission of antibiotic-resistant bacteria and antibiotic resistance genes leading to detrimental effects on human health and environment sustainability. Considering the paramount threat of ever-increasing antibiotic resistance to human health, there is an urgent need for continuous environmental monitoring of antibiotic-resistant bacteria and antibiotic resistance genes in wastewater being used for irrigation in Indian agro-ecosystems. In this study, the prevalence of antibiotic resistance in Gram-negative bacteria isolated from irrigation-purpose wastewater samples from Sirmaur and Solan districts of Himachal Pradesh was determined. Bacterial isolates of genera Escherichia, Enterobacter, Hafnia, Shigella, Citrobacter, and Klebsiella obtained from 11 different geographical locations were found to exhibit resistance against ampicillin, amoxyclav, cefotaxime, co-trimoxazole, tobramycin, cefpodoxime and ceftazidime. However, all the isolates were sensitive to aminoglycoside antibiotic gentamicin. Enterobacter spp. and Escherichia coli showed predominance among all the isolates. Multidrug-resistance phenotype was observed with isolate AUK-06 (Enterobacter sp.) which exhibited resistant to five antibiotics. Isolate AUK-02 and AUK-09, both E. coli strains showed resistant phenotypes to four antibiotics each. Phenotypic detection revealed that six isolates were positive for extended-spectrum β-lactamases which includes two isolates from Enterobacter spp. and E. coli each and one each from Shigella sp. and Citrobacter sp. Overall, the findings revealed the occurrence of antibiotic resistant and ESBL-positive bacterial isolates in wastewaters utilized for irrigation purpose in the study area and necessitate continuous monitoring and precautionary interventions. The outcomes of the study would be of significant clinical, epidemiological, and agro-environmental importance in designing effective wastewater management and environmental pollution control strategies.

A Barrier to Entry: Examining the Bacterial Outer Membrane and Antibiotic Resistance

Gram-negative bacteria can resist antibiotics by changing the permeability via their outer membrane. These bacteria have a complex cell envelope that incorporates an outer membrane separating the periplasm from the external environment. This outer membrane contains many protein channels, also known as porins or nanopores, which mainly allow the influx of hydrophilic compounds, including antibiotics. One probable way bacteria may possibly develop antibiotic resistance is by reworking to reduce the inflow through these outer membrane porins or nanopores. The challenge now is to recognize and potentially comprehend the molecular basis of permeability via the bacterial outer membrane. To address this challenge, this assessment builds upon the author’s previous work to develop a comprehensive understanding of membrane porins and their crucial role in the influx of antibiotics and solutes. Furthermore, the work aspires to investigate the bacterial response to antibiotic membrane permeability and nurture discussion toward further exploration of the physicochemical parameters governing the translocation/transport of antibiotics through bacterial membrane porins. By augmenting our understanding of these mechanisms, we may devise novel approaches to mitigate antibiotic resistance in Gram-negative bacteria.

Identification of natural CTXM-15 inhibitors from aqueous extract of endophytic bacteria Cronobactersakazaki.

Nyctanthes arbor-tristis is one of India's valuable and populous medicinal plants which belongs to the family Oleaceae, and widely recognize as night jasmine. Over the years till date, different parts of the plant are used to treat or cure different ailments via various means of traditional medicine. Endophytes are organisms that live in the cell or body of other organisms with no apparent negative impact on the host which they inhabit and are of great source of novel bioactive compounds possessing important economic value. Secondary metabolites were identified in the aqueous extract of Cronobactersakazakii through quantitative phytochemical and GC-MS analysis. Antibacterial activity of the extract against clinical and ATCC strains of E. coli was assessed. Biological activity spectra of these compounds were predicted and categorized either as probably active (Pa) or probably inactive (Pi). Drug-likeness of bioactive compounds was determined as well as their ability to target protein (CTXM-15) responsible for antibiotic resistance in Gram-negative bacteria. Results revealed the presence of active compounds with pharmacological activities and considerable pharmacokinetics parameters. In addition, ligand-protein interactions of compounds with CTXM-15 proteins were identified. These results suggest that bioactive compounds of endophytic Cronobactersakazakii could contain novel chemical entities for the development of antibiotics against pathogenic microbes and other drugs for the amelioration of several infections.

Antibiotic Susceptibility Patterns for Carbapenem-Resistant Enterobacteriaceae.

Carbapenem is a broad-spectrum beta-lactam antibiotic considered the last choice for the treatment of antibiotic-resistant Gram-negative bacteria. Thus, the increasing rate of carbapenem resistance (CR) in Enterobacteriaceae is an urgent public health threat. This study aimed to evaluate the antibiotic susceptibility pattern of carbapenem-resistant Enterobacteriaceae (CRE) to new and old antibiotics. In this study, Klebsiella pneumoniae, E. coli, and Enterobacter spp. were collected from 10 hospitals in Iran for one year. CRE is recognized by resistance to meropenem and/or imipenem disk after identification of the collected bacteria. Antibiotic susceptibility of CRE against fosfomycin, rifampin, metronidazole, tigecycline, and aztreonam was detected by disk diffusion method and colistin by MIC. In this study, 1222 E. coli, 696 K. pneumoniae, and 621 Enterobacter spp. were collected from 10 hospitals in Iran in one year. Fifty-four E. coli (4.4%), 84 K. pneumoniae (12%), and 51 Enterobacter spp. (8.2%) were CRE. All CRE strains were resistant to metronidazole and rifampicin. Tigecycline has the highest sensitivity on CRE and levofloxacin for Enterobacter spp. Tigecycline showed an acceptable effectiveness rate of sensitivity on the CRE strain. Therefore, we suggest that clinicians consider this valuable antibiotic to treat CRE.

Antimicrobial potency of Punica granatum peel extract: Against multidrug resistant clinical isolates

Normal human flora such as Staphylococcus aureus, Staphylococcus epidermidis, Cutibacterium acnes, Corynebacterium kroppenstedtii, and Escherichia coli could emerge as highly potent opportunistic skin and enteric pathogens. Due to their emerging resistance towards antibiotics, the scope of existing antibacterial therapy and treatment regime is very limited. In the present study, Punica granatum (P. granatum) peel extract is used as an antibacterial agent active against multidrug-resistant bacteria. Interaction with P. granatum peel extract showed strong antibacterial activity with minimum inhibitory concentration value and zone of inhibition ranging between 780 μg/ml to 6250 μg/ml and 20 ± 0.0 to 24.33 ± 2.082 mm respectively. These values evident a strong antibacterial efficacy against antibiotic-resistant Gram-positive (S. aureus, S. epidermidis, C. acnes, and C. kroppenstedtii clinical isolate NB-2) and Gram-negative (E. coli) bacteria. Interestingly, PGP extract also showed a concentration-dependent reduction of biofilm-embedded bacteria, observed 93.2 % ± 1.8 eradication at 25,000 μg/ml with respect to control, in S. epidermidis ATCC 35984 bacterium. PGP extract exhibited strong antioxidant activity and observed 94.7 ± 0.06 % scavenging activity at 1000 μg/ml PGP extract concentration as determined by the cell-free assay. Further, a promising synergistic effect of PGP extract with the commercial antimicrobials such as piroctolamine, zinc pyrithione, and tetracycline against multi-drug resistant, C. kroppenstedtii clinical isolate NB-2 is evaluated. Greater antibacterial potential of the synergistic effect of the peel's extract with the drugs has been observed when compared to the drug alone suggesting that the P. granatum could be the potent antimicrobial agent against antibiotic-resistant skin infection-causing bacteria.

Bacterial physiology: A novel periplasmic glucan promotes cell envelope stress management

A newly discovered pathway relying on the production and modification of periplasmic oligosaccharides is required for proper cell-envelope homeostasis and antibiotic resistance in Gram-negative bacteria.

Crosstalk between imbalanced gut microbiota caused by antibiotic exposure and rotavirus replication in the intestine

ObjectiveRotavirus (RV), one of non-enveloped double-strained RNA viruses, can cause infantile diarrheal illness. It is widely accepted that RV is transmitted mainly via feces-oral route. However, infected asymptomatic adults are becoming the source of infection. It is necessary to explore the underlying mechanism of RV replication in adult's intestine. MethodsAfter recruiting healthy volunteers and RV asymptomatic carriers, we firstly investigated the association of animal-derived food intake with antibiotic level in urine samples. Secondly, we compared the difference in the structure of gut microbiota, and identified the taxa that most likely explained the difference. Finally, we investigated the impact of lipopolysaccharide (LPS), produced by gram-negative bacteria, on RV replication in vivo and in vitro. ResultsWe found that 10% of participants were RV asymptomatic carriers in our study. High intake of animal-derived food was positively correlated to antibiotic level in urine samples. The disrupted gut microbiota in RV carriers was characterized by high abundance of antibiotic resistant gram-negative bacteria and high level of LPS. The disrupted gut microbiota caused by penicillin treatment was benefit to RV replication in vivo. LPS enhanced RV thermal stability in vitro. ConclusionsOur findings suggest that the imbalanced gut microbiota caused by antibiotic exposure plays an important role in RV replication, and brings risk to health complications.