Antibiotic Resistance Related to Biofilm Formation in Klebsiella pneumoniae

A metabolomics footprinting approach using GC-MS to study inhibitory effects of the fungal metabolite diplopyrone C against nosocomial pathogen biofilms

Seen initially as wonder drugs, the widespread and often inappropriate use of antibiotics led to the development of microbial resistances. As a result, a true emergency has arisen, and a significant need has emerged to discover and develop new safe and valuable antibiotics. The captivating chemical structure of the fungal metabolite diplopyrone C has caught our attention as an excellent candidate for a circumstantial study aimed at revealing its antimicrobial and antibiofilm activities. In this work, we describe the full analytical strategy from the isolation/identification to the evaluation of the metabolomics effect on target microorganisms of this fungal metabolite. Our results show interesting antimicrobial and antibiofilm activities of diplopyrone C against two frequently isolated nosocomial pathogens (i.e., the fungus Candida albicans and the gram-negative bacterium Klebsiella pneumoniae). Moreover, a GC-MS based metabolomics footprinting approach gave an insight into the uptake and excretion of metabolites from and into the culture medium as a response to the presence of this active substance. The workflow employed in this study is suitable to exploit natural resources for the search of lead compounds for drug development.

Association Between Biofilm Formation and Extended-Spectrum Beta-Lactamase Production in Klebsiella pneumoniae Isolated from Fresh Fruits and Vegetables

The presence of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in fresh fruits and vegetables is a growing public health concern. The primary objective of this study was to investigate the relationship between biofilm formation and extended-spectrum β-lactamase (ESBL) production in K. pneumoniae strains obtained from fresh fruits and vegetables. Out of 120 samples analysed, 94 samples (78%) were found to be positive for K. pneumoniae. Among the K. pneumoniae strains isolated, 74.5% were from vegetables, whereas the remaining (25.5%) were from fresh fruits. K. pneumoniae isolates were resistant to at least three different classes of antibiotics, with ceftazidime (90%) and cefotaxime (70%) showing the highest resistance rates. While the high occurrence of ESBL-producing and biofilm-forming K. pneumoniae strains were detected in vegetables (73.5% and 73.7%, respectively), considerable amounts of the same were also found in fresh fruits (26.5% and 26.3%, respectively). The results further showed a statistically significant (P < 0.001) association between biofilm formation and ESBL production in K. pneumoniae strains isolated from fresh fruits and vegetables. Furthermore, the majority (81%) of the ESBL-producing strains harbored the blaCTX-M gene, while a smaller proportion of strains carried the blaTEM gene (30%), blaSHV gene (11%) or blaOXA (8%). This study highlights the potential public health threat posed by K. pneumoniae in fresh fruits and vegetables and emphasizes the need for strict surveillance and control measures.

The inhibition mechanism of co-cultured probiotics on biofilm formation of Klebsiella pneumoniae

AIMS

Klebsiella pneumoniae, an important opportunistic pathogen of nosocomial inflection, is known for its ability to form biofilm. The purpose of the current study is to assess how co- or mono-cultured probiotics affect K. pneumoniae's ability to produce biofilms and investigate the potential mechanisms by using a polyester nonwoven chemostat and a Caco-2 cell line.

METHODS AND RESULTS

Compared with pure cultures of Lactobacillus rhamnosus and Lactobacillus sake, the formation of K. pneumoniae biofilm was remarkably inhibited by the mixture of L. rhamnosus, L. sake, and Bacillus subtilis at a ratio of 5:5:1 by means of qPCR and FISH assays. In addition, Lactobacillus in combination with B. subtilis could considerably reduce the adherence of K. pneumoniae to Caco-2 cells by using inhibition, competition, and displacement assays. According to the RT-PCR assay, the adsorption of K. pneumoniae to Caco-2 cells was effectively inhibited by the co-cultured probiotics, leading to significant reduction in the expression of proinflammatory cytokines induced by K. pneumoniae. Furthermore, the HPLC and RT-PCR analyses showed that the co-cultured probiotics were able to successfully prevent the expression of the biofilm-related genes of K. pneumoniae by secreting plenty of organic acids as well as the second signal molecule (c-di-GMP), resulting in inhibition on biofilm formation.

CONCLUSION

Co-culture of L. sake, L. rhamnosus, and B. subtilis at a ratio of 5:5:1 could exert an antagonistic effect on the colonization of pathogenic K. pneumoniae by down-regulating the expression of biofilm-related genes. At the same time, the co-cultured probiotics could effectively inhibit the adhesion of K. pneumoniae to Caco-2 cells and block the expression of proinflammatory cytokines induced by K. pneumoniae.

Comparing antibiotic resistance and virulence profiles of Enterococcus faecium, Klebsiella pneumoniae, and Pseudomonas aeruginosa from environmental and clinical settings

Antibiotic resistance and virulence profiles of Enterococcus faecium, Klebsiella pneumoniae, and Pseudomonas aeruginosa, isolated from water sources collected in informal settlements, were compared to clinical counterparts. Cluster analysis using repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR) indicated that, for each respective species, low genetic relatedness was observed between most of the clinical and environmental isolates, with only one clinical P. aeruginosa (PAO1) and one clinical K. pneumoniae (P2) exhibiting high genetic similarity to the environmental strains. Based on the antibiograms, the clinical E. faecium Ef CD1 was extensively drug resistant (XDR); all K. pneumoniae isolates (n = 12) (except K. pneumoniae ATCC 13883) were multidrug resistant (MDR), while the P. aeruginosa (n = 16) isolates exhibited higher susceptibility profiles. The tetM gene (tetracycline resistance) was identified in 47.4 % (n = 6 environmental; n = 3 clinical) of the E. faecium isolates, while the blaKPC gene (carbapenem resistance) was detected in 52.6 % (n = 7 environmental; n = 3 clinical) and 15.4 % (n = 2 environmental) of the E. faecium and K. pneumoniae isolates, respectively. The E. faecium isolates were predominantly poor biofilm formers, the K. pneumoniae isolates were moderate biofilm formers, while the P. aeruginosa isolates were strong biofilm formers. All E. faecium and K. pneumoniae isolates were gamma (γ)-haemolytic, non-gelatinase producing (E. faecium only), and non-hypermucoviscous (K. pneumoniae only), while the P. aeruginosa isolates exhibited beta (β)-haemolysis and produced gelatinase. The fimH (type 1 fimbriae adhesion) and ugE (uridine diphosphate galacturonate 4-epimerase synthesis) virulence genes were detected in the K. pneumoniae isolates, while the P. aeruginosa isolates possessed the phzM (phenazine production) and algD (alginate biosynthesis) genes. Similarities in antibiotic resistance and virulence profiles of environmental and clinical E. faecium, K. pneumoniae, and P. aeruginosa, thus highlights the potential health risks posed by using environmental water sources for daily water needs in low-and-middle-income countries.

Polyproline peptide targets Klebsiella pneumoniae polysaccharides to collapse biofilms

Hypervirulent Klebsiella pneumoniae is known for its increased extracellular polysaccharide production. Biofilm matrices of hypervirulent K. pneumoniae have increased polysaccharide abundance and are uniquely susceptible to disruption by peptide bactenecin 7 (bac7 (1-35)). Here, using confocal microscopy, we show that polysaccharides within the biofilm matrix collapse following bac7 (1-35) treatment. This collapse led to the release of cells from the biofilm, which were then killed by the peptide. Characterization of truncated peptide analogs revealed that their interactions with polysaccharide were responsible for the biofilm matrix changes that accompany bac7 (1-35) treatment. Ultraviolet photodissociation mass spectrometry with the parental peptide or a truncated analog bac7 (10-35) reveal the important regions for bac7 (1-35) complexing with polysaccharides. Finally, we tested bac7 (1-35) using a murine skin abscess model and observed a significant decrease in the bacterial burden. These findings unveil the potential of bac7 (1-35) polysaccharide interactions to collapse K. pneumoniae biofilms.

Mechanisms of Antibiotic Resistance and Developments in Therapeutic Strategies to Combat Klebsiella pneumoniae Infection

Infections with drug-resistant bacteria have become one of the greatest public health challenges, and K. pneumoniae is among the top six drug-resistant bacteria. K. pneumoniae often causes nosocomial infections, leading to illnesses such as pneumonia, liver abscesses, soft tissue infections, urinary tract infections, bacteremia, and in some cases death. As the pathogen continues to evolve and its multidrug resistance increases, K. pneumoniae poses a direct threat to humans. Drug resistance in K. pneumoniae may occur due to the formation of biofilms, efflux pumps, and the production of β-lactamases. In many cases, resistance is further enhanced by enzymatic modification and loss of porins. Drug resistance to K. pneumoniae has led to a decline in the effectiveness of conventional therapies against this pathogen. Therefore, there is an urgent need to accelerate the development of new antibiotics and explore new therapeutic approaches such as antimicrobial peptides, phages, traditional Chinese medicine, immunotherapy, Antimicrobial nanoparticle technology, antisense oligonucleotides and gene editing technologies. In this review, we discuss the mechanisms of drug resistance in K. pneumoniae and compare several new potential therapeutic strategies to overcome drug resistance in the treatment of K. pneumoniae infections.

Plant-Origin Components: New Players to Combat Antibiotic Resistance in Klebsiella pneumoniae

Klebsiella pneumoniae (Kpn) is an opportunistic pathogen that causes intrahospital complications such as pneumonia, liver abscesses, soft tissue infections, urinary infections, bacteraemia, and, in some cases, death. Since this bacterium has a higher frequency than other Gram-negative pathogens, it has become an important pathogen to the health sector. The adaptative genome of Kpn likely facilitates increased survival of the pathogen in diverse situations. Therefore, several studies have been focused on developing new molecules, synergistic formulations, and biomaterials that make it possible to combat and control infections with and dispersion of this pathogen. Note that the uncontrolled antibiotic administration that occurred during the pandemic led to the emergence of new multidrug-resistant strains, and scientists were challenged to overcome them. This review aims to compile the latest information on Kpn that generates intrahospital infections, specifically their pathogenicity-associated factors. Furthermore, it explains the natural-product-based treatments (extracts and essential oils) developed for Kpn infection and dispersion control.

Inorganic Polyphosphate Affects Biofilm Assembly, Capsule Formation, and Virulence of Hypervirulent ST23 Klebsiella pneumoniae

The emergence of hypervirulent Klebsiella pneumoniae (hvKP) strains poses a significant threat to public health due to high mortality rates and propensity to cause severe community-acquired infections in healthy individuals. The ability to form biofilms and produce a protective capsule contributes to its enhanced virulence and is a significant challenge to effective antibiotic treatment. Polyphosphate kinase 1 (PPK1) is an enzyme responsible for inorganic polyphosphate synthesis and plays a vital role in regulating various physiological processes in bacteria. In this study, we investigated the impact of polyP metabolism on the biofilm and capsule formation and virulence traits in hvKP using Dictyostelium discoideum amoeba as a model host. We found that the PPK1 null mutant was impaired in biofilm and capsule formation and showed attenuated virulence in D. discoideum compared to the wild-type strain. We performed a proteomic analysis to gain further insights into the underlying molecular mechanism. The results revealed that the PPK1 mutant had a differential expression of proteins involved in capsule synthesis (Wzi-Ugd), biofilm formation (MrkC-D-H), synthesis of the colibactin genotoxin precursor (ClbB), as well as proteins associated with the synthesis and modification of lipid A (ArnB-LpxC-PagP). These proteomic findings corroborate the phenotypic observations and indicate that the PPK1 mutation is associated with impaired biofilm and capsule formation and attenuated virulence in hvKP. Overall, our study highlights the importance of polyP synthesis in regulating extracellular biomolecules and virulence in K. pneumoniae and provides insights into potential therapeutic targets for treating K. pneumoniae infections.

Proline-Hinged α-Helical Peptides Sensitize Gram-Positive Antibiotics, Expanding Their Physicochemical Properties to Be Used as Gram-Negative Antibiotics

The outer membrane (OM) of Gram-negative bacteria is the most difficult obstacle for small-molecule antibiotics to reach their targets in the cytosol. The molecular features of Gram-negative antibiotics required for passing through the OM are that they should be positively charged rather than neutral, flat rather than globular, less flexible, or more increased amphiphilic moment. Because of these specific molecular characteristics, developing Gram-negative antibiotics is difficult. We focused on sensitizer peptides to facilitate the passage of hydrophobic Gram-positive antibiotics through the OM. We explored ways of improving the sensitizing ability of proline-hinged α-helical peptides by adjusting their length, hydrophobicity, and N-terminal groups. A novel peptide, 1403, improves the potentiation of rifampicin in vitro and in vivo and potentiates most Gram-positive antibiotics. The "sensitizer" approach is more plausible than those that rely on conventional drug discovery methods concerning drug development costs and the development of drug resistance.

Use of Essential Oils to Counteract the Phenomena of Antimicrobial Resistance in Livestock Species

Antimicrobial resistance is an increasingly widespread phenomenon that is of particular concern because of the possible consequences in the years to come. The dynamics leading to the resistance of microbial strains are diverse, but certainly include the incorrect use of veterinary drugs both in terms of dosage and timing of administration. Moreover, the drug is often administered in the absence of a diagnosis. Many active ingredients in pharmaceutical formulations are, therefore, losing their efficacy. In this situation, it is imperative to seek alternative treatment solutions. Essential oils are mixtures of compounds with different pharmacological properties. They have been shown to possess the antibacterial, anti-parasitic, antiviral, and regulatory properties of numerous metabolic processes. The abundance of molecules they contain makes it difficult for treated microbial species to develop pharmacological resistance. Given their natural origin, they are environmentally friendly and show little or no toxicity to higher animals. There are several published studies on the use of essential oils as antimicrobials, but the present literature has not been adequately summarized in a manuscript. This review aims to shed light on the results achieved by the scientific community regarding the use of essential oils to treat the main agents of bacterial infection of veterinary interest in livestock. The Google Scholar, PubMed, SciELO, and SCOPUS databases were used for the search and selection of studies. The manuscript aims to lay the foundations for a new strategy of veterinary drug use that is more environmentally friendly and less prone to the emergence of drug resistance phenomena.

Observations on phenomenological changes in Klebsiella Pneumoniae under fluidic stresses

In the present work, experiments are conducted to understand the consequence of stresses generated by flowing fluid on the bacterial morphology and virulence in microfluidic channels. We consider Klebsiella pneumoniae (KP, a clinical isolate), an ESKAPE pathogen, to be the model bacteria responsible for blood stream infections, bacteremia, including pneumonia, urinary tract infections and more. Four different stress conditions are generated by changing the flow rate and channel geometry subsequently altering the shear rate and stressing time (τ). We observe significant changes in the structural aspects of the stressed bacteria. With an increase in stressing parameters, the viability of the bacterial sample deteriorated. Most importantly, these stressed samples proliferate much more than unstressed samples inside the RAW264.7 murine macrophages. The results shed light on the complex relationship between flow stresses and bacterial virulence. Furthermore, the bacterial samples are challenged with ciprofloxacin to see how they behave under different stress conditions. The observations presented in the present study can be extended to model deadly diseases including bacteremia using organ-on-a-chip technology and to understand bacterial pathogenicity under realistic environments.

Ceragenins and Ceragenin-Based Core-Shell Nanosystems as New Antibacterial Agents against Gram-Negative Rods Causing Nosocomial Infections

The growing number of infections caused by multidrug-resistant bacterial strains, limited treatment options, multi-species infections, high toxicity of the antibiotics used, and an increase in treatment costs are major challenges for modern medicine. To remedy this, scientists are looking for new antibiotics and treatment methods that will effectively eradicate bacteria while continually developing different resistance mechanisms. Ceragenins are a new group of antimicrobial agents synthesized based on molecular patterns that define the mechanism of antibacterial action of natural antibacterial peptides and steroid-polyamine conjugates such as squalamine. Since ceragenins have a broad spectrum of antimicrobial activity, with little recorded ability of bacteria to develop a resistance mechanism that can bridge their mechanism of action, there are high hopes that this group of molecules can give rise to a new family of drugs effective against bacteria resistant to currently used antibiotics. Experimental data suggests that core-shell nanosystems, in which ceragenins are presented to bacterial cells on metallic nanoparticles, may increase their antimicrobial potential and reduce their toxicity. However, studies should be conducted, among others, to assess potential long-term cytotoxicity and in vivo studies to confirm their activity and stability in animal models. Here, we summarized the current knowledge on ceragenins and ceragenin-containing nanoantibiotics as potential new tools against emerging Gram-negative rods associated with nosocomial infections.

Evolving biofilm inhibition and eradication in clinical settings through plant-based antibiofilm agents

BACKGROUND

After almost 100 years since evidence of biofilm mode of growth and decades of intensive investigation about their formation, regulatory pathways and mechanisms of antimicrobial tolerance, nowadays there are still no therapeutic solutions to eradicate bacterial biofilms and their biomedical related issues.

PURPOSE

This review intends to provide a comprehensive summary of the recent and most relevant published studies on plant-based products, or their isolated compounds with antibiofilm activity mechanisms of action or identified molecular targets against bacterial biofilms. The objective is to offer a new perspective of most recent data for clinical researchers aiming to prevent or eliminate biofilm-associated infections caused by bacterial pathogens.

METHODS

The search was performed considering original research articles published on PubMed, Web of Science and Scopus from 2015 to April 2023, using keywords such as "antibiofilm", "antivirulence", "phytochemicals" and "plant extracts".

RESULTS

Over 180 articles were considered for this review with a focus on the priority human pathogens listed by World Health Organization, including Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Inhibition and detachment or dismantling of biofilms formed by these pathogens were found using plant-based extract/products or derivative compounds. Although combination of plant-based products and antibiotics were recorded and discussed, this topic is currently poorly explored and only for a reduced number of bacterial species.

CONCLUSIONS

This review clearly demonstrates that plant-based products or derivative compounds may be a promising therapeutic strategy to eliminate bacterial biofilms and their associated infections. After thoroughly reviewing the vast amount of research carried out over years, it was concluded that plant-based products are mostly able to prevent biofilm formation through inhibition of quorum sensing signals, but also to disrupt mature biofilms developed by multidrug resistant bacteria targeting the biofilm extracellular polymeric substance. Flavonoids and phenolic compounds seemed the most effective against bacterial biofilms.

Advances in Material Modification with Smart Functional Polymers for Combating Biofilms in Biomedical Applications

Biofilms as living microorganism communities are found anywhere, and for the healthcare sector, these constitute a threat and allied mechanism for health-associated or nosocomial infections. This review states the basis of biofilms and their formation. It focuses on their relevance for the biomedical sector, generalities, and the major advances in modified or new synthesized materials to prevent or control biofilm formation in biomedicine. Biofilm is conceptualized as an aggregate of cells highly communicated in an extracellular matrix, which the formation obeys to molecular and genetic basis. The biofilm offers protection to microorganisms from unfavorable environmental conditions. The most frequent genera of microorganisms forming biofilms and reported in infections are Staphylococcus spp., Escherichia spp., and Candida spp. in implants, heart valves, catheters, medical devices, and prostheses. During the last decade, biofilms have been most commonly related to health-associated infections and deaths in Europe, the United States, and Mexico. Smart, functional polymers are materials capable of responding to diverse stimuli. These represent a strategy to fight against biofilms through the modification or synthesis of new materials. Polypropylene and poly-N-isopropyl acrylamide were used enough in the literature analysis performed. Even smart polymers serve as delivery systems for other substances, such as antibiotics, for biofilm control.

Evaluation of the Ability to Form Biofilms in KPC-Producing and ESBL-Producing Klebsiella pneumoniae Isolated from Clinical Samples

The appearance of Klebsiella pneumoniae strains producing extended-spectrum β-lactamase (ESBL), and carbapenemase (KPC) has turned into a significant public health issue. ESBL- and KPC-producing K. pneumoniae's ability to form biofilms is a significant concern as it can promote the spread of antibiotic resistance and prolong infections in healthcare facilities. A total of 45 K. pneumoniae strains were isolated from human infections. Antibiograms were performed for 17 antibiotics, ESBL production was tested by Etest ESBL PM/PML, a rapid test was used to detect KPC carbapenemases, and resistance genes were detected by PCR. Biofilm production was detected by the microtiter plate method. A total of 73% of multidrug resistance was found, with the highest resistance rates to ampicillin, trimethoprim-sulfamethoxazole, cefotaxime, amoxicillin-clavulanic acid, and aztreonam. Simultaneously, the most effective antibiotics were tetracycline and amikacin. bla_CTX-M, bla_TEM, bla_SHV, aac(3)-II, aadA1, tetA, cmlA, catA, gyrA, gyrB, parC, sul1, sul2, sul3, bla_KPC, bla_OXA, and bla_PER genes were detected. Biofilm production showed that 80% of K. pneumoniae strains were biofilm producers. Most ESBL- and KPC-producing isolates were weak biofilm producers (40.0% and 60.0%, respectively). There was no correlation between the ability to form stronger biofilms and the presence of ESBL and KPC enzymes in K. pneumoniae isolates.

Revisiting ESKAPE Pathogens: virulence, resistance, and combating strategies focusing on quorum sensing

The human-bacterial association is long-known and well-established in terms of both augmentations of human health and attenuation. However, the growing incidents of nosocomial infections caused by the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp.) call for a much deeper understanding of these organisms. Adopting a holistic approach that includes the science of infection and the recent advancements in preventing and treating infections is imperative in designing novel intervention strategies against ESKAPE pathogens. In this regard, this review captures the ingenious strategies commissioned by these master players, which are teamed up against the defenses of the human team, that are equally, if not more, versatile and potent through an analogy. We have taken a basketball match as our analogy, dividing the human and bacterial species into two teams playing with the ball of health. Through this analogy, we make the concept of infectious biology more accessible.

What’s old is new again: Insights into diabetic foot microbiome

Diabetes is a chronic disease that is considered one of the most stubborn global health problems that continues to defy the efforts of scientists and physicians. The prevalence of diabetes in the global population continues to grow to alarming levels year after year, causing an increase in the incidence of diabetes complications and health care costs all over the world. One major complication of diabetes is the high susceptibility to infections especially in the lower limbs due to the immunocompromised state of diabetic patients, which is considered a definitive factor in all cases. Diabetic foot infections continue to be one of the most common infections in diabetic patients that are associated with a high risk of serious complications such as bone infection, limb amputations, and life-threatening systemic infections. In this review, we discussed the circumstances associated with the high risk of infection in diabetic patients as well as some of the most commonly isolated pathogens from diabetic foot infections and the related virulence behavior. In addition, we shed light on the different treatment strategies that aim at eradicating the infection.

Synergy of Plant Essential Oils in Antibiotic Therapy to Combat Klebsiella pneumoniae Infections

Increased antibiotic resistance presents a health problem worldwide. The World Health Organization published a list of pathogens considered a priority for designing new treatments. Klebsiella pneumoniae (Kp) is a top-priority microorganism, highlighting the strains that produce carbapenemases. Developing new efficient therapies or complementing existing treatments is a priority, and essential oils (EOs) provide an alternative. EOs could act as antibiotic adjuvants and enhance antibiotic activity. Employing standard methodologies, the antibacterial activity of the EOs and their synergic effect with antibiotics were detected. A string test was used to identify the impact of the EOs over the hypermucoviscosity phenotype presented by Kp strains, and Gas Chromatography-Mass Spectrometry analysis identified EOs and the composition of EOs. The potential of EOs for designing synergistic therapies with antibiotics to combat the infection of KPC diseases was demonstrated. In addition, the alteration of the hypermucoviscosity phenotype was shown as the principal mechanism of a synergic action between EOs and antibiotics. The differential composition of the EOs lets us identify some molecules that will be analyzed. Synergic activity of EOs and antibiotics can provide a solid platform for combating multiresistant pathogens that represent a severe health sector problem, such as Kp infections.

Hematogenous prosthetic knee joint infection with Klebsiella pneumoniae caused by asymptomatic gallbladder abscess: a case report and literature review

Klebsiella pneumoniae has the ability to form biofilm; therefore, the treatment of prosthetic joint infection involving K. pneumoniae is often challenging. This report describes the first case of acute hematogenous prosthetic knee joint infection with K. pneumoniae that occurred as a result of an asymptomatic gallbladder abscess. The patient was a 78-year-old man who underwent bilateral total knee arthroplasty 6 years ago. He had pain and swelling in his right knee. The synovial fluid culture of the right knee revealed K. pneumoniae and prosthetic joint infection was diagnosed. Computed tomography revealed a gallbladder abscess in the absence of right upper abdominal pain. The patient underwent simultaneous debridement of the knee and open cholecystectomy. The treatment was successful and the prosthesis was retained. In cases of hematogenous prosthetic joint infection with K. pneumoniae, other sources of infection should be suspected and investigated regardless of whether they are symptomatic.

Alterations in Antibiotic Susceptibility of Staphylococcus aureus and Klebsiella pneumoniae in Dual Species Biofilms

In the last decades, it has been shown that biofilm-associated infections in most cases are caused by rather two or even more pathogens than by single microorganisms. Due to intermicrobial interactions in mixed communities, bacteria change their gene expression profile, in turn leading to alterations in the biofilm structure and properties, as well as susceptibility to antimicrobials. Here, we report the alterations of antimicrobials efficiency in mixed biofilms of Staphylococcus aureus-Klebsiella pneumoniae in comparison with mono-species biofilms of each counterpart and discuss possible mechanisms of these alterations. In cell clumps detached from dual-species biofilms, S. aureus became insensitive to vancomycin, ampicillin, and ceftazidime compared to solely S. aureus cell clumps. In turn, the increased efficiency of amikacin and ciprofloxacin against both bacteria could be observed, compared to mono-species biofilms of each counterpart. Scanning electron microscopy and confocal microscopy indicate the porous structure of the dual-species biofilm, and differential fluorescent staining revealed an increased number of polysaccharides in the matrix, in turn leading to more loose structure and thus apparently providing increased permeability of the dual-species biofilm to antimicrobials. The qRT-PCR showed that ica operon in S. aureus became repressed in mixed communities, and polysaccharides are produced mainly by K. pneumoniae. While the molecular trigger of these changes remains undiscovered, detailed knowledge of the alterations in antibiotic susceptibility to given drugs opens doors for treatment correction options for S. aureus-K. pneumoniae biofilm-associated infections.

Phages for treatment of Klebsiella pneumoniae infections

Klebsiella pneumoniae is an opportunistic pathogen involved in both hospital- and community-acquired infections. K. pneumoniae is associated with various infections, including pneumonia, septicemia, meningitis, urinary tract infection, and surgical wound infection. K. pneumoniae possesses serious virulence, biofilm formation ability, and severe resistance to many antibiotics especially hospital-acquired strains, due to excessive use in healthcare systems. This limits the available effective antibiotics that can be used for patients suffering from K. pneumoniae infections; therefore, alternative treatments are urgently needed. Bacteriophages (for short, phages) are prokaryotic viruses capable of infecting, replicating, and then lysing (lytic phages) the bacterial host. Phage therapy exhibited great potential for treating multidrug-resistant bacterial infections comprising K. pneumoniae. Hence, this chapter emphasizes and summarizes the research articles in the PubMed database from 1948 until the 15th of December 2022, addressing phage therapy against K. pneumoniae. The chapter provides an overview of K. pneumoniae phages covering different aspects, including phage isolation, different morphotypes of isolated phages, in vitro characterization, anti-biofilm activity, various therapeutic forms, in vivo research and clinical studies.

Antibiotic Susceptibility, Biofilm-Forming Ability, and Prevalence of Extended-Spectrum Beta-Lactamase (ESBL)- and Biofilm-Associated Genes Among Klebsiella pneumoniae Isolates from Hospitalized Patients in Northwest of Iran

Klebsiella pneumoniae is an opportunistic bacterium, which is globally recognized for its high prevalence and antimicrobial resistance (AMR). Biofilm-forming capability, susceptibility testing, and phenotypic confirmatory test for extended-spectrum beta-lactamase (ESBL)-producing isolate recognition of 104 K. pneumoniae isolates were performed according to the Clinical Laboratory Standard Institute (CLSI) guidelines. The prevalence of ESBL-associated genes bla-VIM, bla-NDM, and bla-OXA-48, as well as biofilm-associated genes luxS, fimH1, wza, and mrkD, was determined by multiplex PCR. The highest resistance rate was against ampicillin (100.0%). Among the 104 K. pneumoniae isolates, 52 (50.0%) and 31 (29.8%) isolates were determined as multi- and extensively drug resistant (MDR, XDR), respectively. Moreover, 21 (40.4%) isolates were determined as ESBL producing. Among 50 biofilm-producing K. pneumoniae isolates, 7 (14.0%), 15 (30.0%), and 28 (56.0%) isolates exhibited high, moderate, and weak levels of biofilm formation, respectively. A number of 41 (78.8%) isolates were susceptible to colistin, and 10 (19.2%) were resistant. AMR was significantly higher (P < 0.05) in the biofilm-forming isolates compared with non-biofilm formers.

In Vitro Activity of Fosfomycin on Multidrug-Resistant Strains of Klebsiella pneumoniae and Klebsiella oxytoca Causing Urinary Tract Infection

With the emergence of multi-drug resistant strains among Klebsiella isolates, the use of old drugs such as fosfomycin has been considered. In this context, we investigated the effect of fosfomycin on biofilm-producing Klebsiella pneumoniae and Klebsiella oxytoca strains isolated from ICU patients. A total of 90 isolates of Klebsiella pneumoniae and 30 isolates of Klebsiella oxytoca were collected from the ICU ward. All isolates were confirmed by biochemical and genotypic methods. Antibiotic susceptibility testing was performed by disc diffusion method and for fosfomycin and colistin, minimum inhibitory concentration (MIC) was done using micro broth dilution. The presence of the beta-lactamase encoding genes, biofilm-related genes, and fosfomycin resistance-related genes was detected by PCR. Finally, for fosfomycin-resistant isolates, we determined the sequence type by the MLST method. Sensitivity rate to fosfomycin in Klebsiella pneumoniae and Klebsiella oxytoca isolates was 92.2% and 100%, respectively. Fosfomycin was the most active antimicrobial agent with 96% sensitivity among all tested antibiotics. All tested isolates could produce biofilm. The frequency of biofilm-related genes for Klebsiella pneumoniae was as follows: 95.5% fimH, 86.6% mrkD, 77.7% mrkA, and 50% wcaG. The frequency of these genes for Klebsiella oxytoca was as follows: 56.6% fimA, 46.6% mrkA, 93.3% matB, and 90% pilQ. Only 4.4% of Klebsiella pneumoniae isolates showed resistance to fosfomycin, and the fosA gene was detected in all of them. Our results showed that fosfomycin effectively inhibits multidrug-resistant (MDR) strains of Klebsiella pneumoniae and Klebsiella oxytoca.

Investigating Klebsiella pneumoniae biofilm preservation for scanning electron microscopy

Klebsiella pneumoniae biofilm formation is associated with chronic and relapsing infections. Scanning electron microscopy (SEM) is a powerful tool for characterizing biofilm structure and studying their formation. Reliable visualization of biofilm structure requires careful sample preservation, otherwise there may be loss of non-covalent interactions that are susceptible to damage during the dehydration and washing preparation steps. However, no standard procedure has been adopted in the literature to fix K. pneumoniae biofilm for scanning electron microscopy studies. This lack of standardization makes it challenging to compare results between studies and determine the degree to which native structures have been preserved. To advance this critical area of study, we investigated different scanning electron microscopy fixation methods for K. pneumoniae biofilm preservation. Our study reveals the impact preparation steps can have on retaining in biofilm architecture observed using scanning electron microscopy. Using fixation methods developed through our studies, we show that although species that overproduce capsular extracellular polysaccharides produced more robust biofilms, K. pneumoniae can form a developed biofilm in the absence of capsular polysaccharides.

Asymptomatic nasopharyngeal bacterial carriage, multi-drug resistance pattern and associated factors among primary school children at Debre Berhan town, North Shewa, Ethiopia

BACKGROUND

Nasopharyngeal carriage of bacteria is the main source for transmission of pathogens across individuals and horizontal spread of organisms in the community. It is an important risk factor for the acquisition of community-acquired respiratory tract infection. It is the major public health problem among children. The asymptomatic carriage of nasopharyngeal bacteria is different globally, particularly in Africa, carriage is higher in children and decreases with increasing age, 63.2% in children less than 5 years, 42.6% in children 5-15 years, and 28.0% in adults older than 15 years.

OBJECTIVE

The aims of this study was to determine asymptomatic nasopharyngeal bacterial carriage, multi-drug resistance pattern and associated factors among primary school children at Debre Berhan town, North Shewa, Ethiopia.

METHODS

Institutional based cross-sectional study was conducted at Debre Berhan town primary schools from February 1 to April 30, 2021. Primarily, the schools were stratified into two strata, public and private primary schools. From a total of sixteen government and fourteen private primary schools, five government and five private schools were selected by using a simple random sampling technique. Socio-demographic variables and potential risk factors were assessed using a structured questionnaire. A total of 384 nasopharyngeal swab samples were collected using sterile swabs aseptically; and inoculated on Blood agar, Chocolate agar, MacConkey agar, and Mannitol salt agar. The colony was characterized to isolate bacteria, and bacterial identification was performed by Gram reaction, hemolysis patterns, colonial characteristics and pigmentation, catalase test, coagulase test, mannitol fermentation test, oxidase test, fermentation of carbohydrates, H₂S production, motility, formation of indole, triple sugar iron agar (TSI), citrate utilization, lysine decarboxylase or methyl red vogues proskur utilization, urea hydrolysis and satellitism tests. Antimicrobial sensitivity tests were performed by using modified Kirby-Bauer disk diffusion method. Data were entered into statistical package Epi data 4.0.0.6 and transferred to and analyzed using SPSS software version-23. P value of < 0.05 with Odds ratio (OR) and 95% confidence interval (CIs) was considered as statistically significant.

RESULTS

The overall prevalence of nasopharyngeal carriage of bacterial isolate was 35.7% (95% CI 30.7-40.7%). The predominant isolates were Staphylococcus aureus 54.5% followed by coagulase-negative Staphylococcus 35.8%, and Streptococcus pyogens 4.5%. Most bacterial isolates were susceptible to chloramphenicol, ciprofloxacin, gentamycin, nitrofurantoin, azithromycin, ciprofloxacin; and the overall multidrug resistance pattern of isolated bacteria was 62.03% out of 137 bacterial isolates. Numbers of rooms ≤ 2 per house [AOR = 5.88, 95%CI 1.26-27.57], having history of hospitalization [AOR = 4.08, 95%CI 1.45-11.53], passive smoking [AOR = 4.87, 95%CI 1.49-15.97], family size of > 5 members [AOR = 2.17, 95%CI 1.24-3.81], and number of students in the classroom [AOR = 2.35,95%CI 1.37-4.02] were statistically significant associated risk factors for nasopharyngeal bacteria carriage.

CONCLUSION

Asymptomatic nasopharyngeal bacteria carriage in children is alarming for community-acquired infection. The overall multidrug resistance was very high. The risk of the carriage was increased with having a history of passive smoking, being in large family size and number of students per class. Longitudinal follow-up studies would be helpful for better understanding the infection risk in bacterial pathogen carriers.

An Explorative Review on Advanced Approaches to Overcome Bacterial Resistance by Curbing Bacterial Biofilm Formation

The continuous emergence of multidrug-resistant pathogens evoked the development of innovative approaches targeting virulence factors unique to their pathogenic cascade. These approaches aimed to explore anti-virulence or anti-infective therapies. There are evident concerns regarding the bacterial ability to create a superstructure, the biofilm. Biofilm formation is a crucial virulence factor causing difficult-to-treat, localized, and systemic infections. The microenvironments of bacterial biofilm reduce the efficacy of antibiotics and evade the host's immunity. Producing a biofilm is not limited to a specific group of bacteria; however, Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus biofilms are exemplary models. This review discusses biofilm formation as a virulence factor and the link to antimicrobial resistance. In addition, it explores insights into innovative multi-targeted approaches and their physiological mechanisms to combat biofilms, including natural compounds, phages, antimicrobial photodynamic therapy (aPDT), CRISPR-Cas gene editing, and nano-mediated techniques.

Biofilm Lifestyle in Recurrent Urinary Tract Infections

Urinary tract infections (UTIs) represent one of the most common infections that are frequently encountered in health care facilities. One of the main mechanisms used by bacteria that allows them to survive hostile environments is biofilm formation. Biofilms are closed bacterial communities that offer protection and safe hiding, allowing bacteria to evade host defenses and hide from the reach of antibiotics. Inside biofilm communities, bacteria show an increased rate of horizontal gene transfer and exchange of resistance and virulence genes. Additionally, bacterial communication within the biofilm allows them to orchestrate the expression of virulence genes, which further cements the infestation and increases the invasiveness of the infection. These facts stress the necessity of continuously updating our information and understanding of the etiology, pathogenesis, and eradication methods of this growing public health concern. This review seeks to understand the role of biofilm formation in recurrent urinary tact infections by outlining the mechanisms underlying biofilm formation in different uropathogens, in addition to shedding light on some biofilm eradication strategies.

FeoC from Klebsiella pneumoniae uses its iron sulfur cluster to regulate the GTPase activity of the ferrous iron channel

Bacteria depend on the ferrous iron transport (Feo) system for the uptake of ferrous iron (Fe²⁺). The Feo system is crucial for colonization and virulence of pathogens. In γ-proteobacteria, the system consists of FeoA, FeoB, and FeoC. The function of FeoA remains unknown. FeoB likely forms the channel, whose regulation has been suggested to involve its GTPase domain (part of its NFeoB domain). FeoC from Klebsiella pneumonia was found to contain a [4Fe4S] cofactor, whose presence was speculated to enhance the GTPase activity of FeoB (Hsueh, K.-L., et al., J. Bacteriol. 2013 195(20): 4726-34). We present results here that support and extend that hypothesis. We monitored the GTPase activity of FeoB by NMR spectroscopy and found that the presence of 7% FeoC-[4Fe-4S]³⁺ (the highest level of cofactor achieved in vitro) increased the GTPase rate of NFeoB by 3.6-fold over NFeoB. The effect depends on the oxidation state of the cluster; with reduction of the cluster to [4Fe-4S]²⁺ the GTPase greatly decreased the GTPase rate. From the effects of point mutations in FeoC on GTPase rates, we conclude that Lys62 and Lys68 on FeoC each contribute to increased GTPase activity on NFeoB. Mutation of Thr37 of NFeoB to Ser nearly abolished the GTPase activity. The GTPase activity of the isolated K. pneumoniae NFeoB-FeoC complex (NFeoBC) was found to be higher in KCl than in NaCl solution. We solved the X-ray structure of the NFeoBC crystallized from KCl and compared it with a prior X-ray structure crystalized from NaCl. We propose a hypothesis, consistent with these results, to explain the factors that influence the GTPase activity. Bacteria may use the oxygen-sensitive cluster as a sensor to up-regulate the gate closing speed.

Klebsiella pneumoniae: an update on antibiotic resistance mechanisms

Klebsiella pneumoniae colonizes mucosal surfaces of healthy humans and is responsible for one third of all Gram-negative infections in hospitalized patients. K. pneumoniae is compatible with acquiring antibiotic resistance elements such as plasmids and transposons encoding various β-lactamases and efflux pumps. Mutations in different proteins such as β-lactamases, efflux proteins, outer membrane proteins, gene replication enzymes, protein synthesis complexes and transcription enzymes also generate resistance to antibiotics. Biofilm formation is another strategy that facilitates antibiotic resistance. Resistant strains can be treated by combination therapy using available antibiotics, though proper management of antibiotic consumption in hospitals is important to reduce the emergence and proliferation of resistance to current antibiotics.

Synergistic effect and antibiofilm activity of the antimicrobial peptide K11 with conventional antibiotics against multidrug-resistant and extensively drug-resistant Klebsiella pneumoniae

Introduction

Infections caused by drug-resistant Klebsiella pneumoniae are now a serious problem for public health, associated with high morbidity and mortality due to limited treatment options. Therefore, new antibacterial agents or a combination of agents as the first line of treatment are urgently needed. K11 is a novel antimicrobial peptide (AMP) that has demonstrated in vitro antimicrobial activity against several types of bacteria. Additionally, K11 has previously shown no hemolytic activity. Herein, the antibacterial activity, the synergistic action of K11 in combination with different conventional antibiotics and the antibiofilm activity of K11 against multidrug-resistant (MDR) and extensively drug-resistant (XDR) K. pneumoniae were investigated. Meanwhile, the stability and ability to induce the bacterial resistance of K11 were also tested.

Methods

Fifteen clinical isolates of MDR/XDR K. pneumoniae were used in this study. The minimum inhibitory concentration (MIC) of K11 against these isolates was determined by the broth microdilution method. In vitro synergy between K11 and antibiotics was evaluated using the checkerboard methodology. The antibiofilm activity of K11 against K. pneumoniae strong biofilm producers were explored by the crystal violet staining. The stability in different environments and resistance induction of K11 were evaluated by MIC determination.

Results

The MIC values of K11 against MDR/XDR K. pneumoniae isolates were 8-512 μg/mL. Intriguingly, the synergistic effects were clearly observed for K11 in combination with chloramphenicol, meropenem, rifampicin, or ceftazidime, whereas no synergy was observed when K11 was combined with colistin. Besides, K11 effectively prevented biofilm formation against K. pneumoniae strong biofilm producers in a concentration-dependent manner starting at 0.25×MIC and exerted an enhancing effect when administered in combination with meropenem, chloramphenicol, or rifampicin. Additionally, K11 demonstrated high thermal and wide pH stability along with good stability in serum and physiological salts. Significantly, K. pneumoniae showed no induction of resistance even after prolonged exposure to a sub-inhibitory concentration of K11.

Conclusion

These findings indicate that K11 is a promising candidate with potent antibacterial and antibiofilm activities without inducing resistance and acts synergistically with conventional antibiotics against drug-resistant K. pneumoniae.

Biochemical and molecular mechanisms of antibiotic resistance in Salmonella spp

Salmonella is a diverse Gram-negative bacterium that represents the major disease burden worldwide. According to WHO, Salmonella is one of the fourth global causes of diarrhoeal disease. Antibiotic resistance is a worldwide health concern, and Salmonella spp. is one of the microorganisms that can evade the toxicity of antimicrobials via antibiotic resistance. This review aims to deliver in-depth knowledge of the molecular mechanisms and the underlying biochemical alterations perceived in antibiotic resistance in Salmonella. This information will help understand and mitigate the impact of antibiotic-resistant bacteria on humans and contribute to the state-of-the-art research developing newer and more potent antibiotics.

Recent Advances in Nanotechnology for the Management of Klebsiella pneumoniae-Related Infections

Klebsiella pneumoniae is an important human pathogen that causes diseases such as urinary tract infections, pneumonia, bloodstream infections, bacteremia, and sepsis. The rise of multidrug-resistant strains has severely limited the available treatments for K. pneumoniae infections. On the other hand, K. pneumoniae activity (and related infections) urgently requires improved management strategies. A growing number of medical applications are using nanotechnology, which uses materials with atomic or molecular dimensions, to diagnose, eliminate, or reduce the activity of different infections. In this review, we start with the traditional treatment and detection method for K. pneumoniae and then concentrate on selected studies (2015-2022) that investigated the application of nanoparticles separately and in combination with other techniques against K. pneumoniae.

Potential for Microbial Cross Contamination of Laundry from Public Washing Machines

Although clothes washing machines remove dirt, microorganisms are not reliably removed by modern cold-water machine-washing practices. Microbial bioburden on clothing originates from the wearer’s skin, the environment (indoor and outdoor), and the washing machine itself. While most clothing microbes are commensals, microbes causing odors and opportunistic pathogens may also be present. Understanding the extent of microbial transfer from washing machines to clothes may inform strategies for odor control and for mitigating the transmission of microbes through the laundering process. This study was designed to quantify and identify bacteria/fungi transferred from laundromat machines to sentinel cotton washcloths under standard cold-water conditions. Bacterial 16S rRNA and fungal ITS sequencing enabled identification of microorganisms in the washcloths following laundering. Total plate-based enumeration of viable microorganisms also was performed, using growth media appropriate for bacteria and fungi. Opportunistic human bacterial pathogens, including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp., were recovered. The fungal bioburden was ~two-fold lower than the bacterial bioburden. Most sequences recovered were assigned to non-pathogenic fungi, such as those from genera Malassezia and Ascomycota. These results suggest that public washing machines represent a source of non-pathogenic and pathogenic microbial contamination of laundered garments.

Isolation, Characterization, and Effect on Biofilm Formation of Bacteriocin Produced by Lactococcus lactis F01 Isolated from Cyprinus carpio and Application for Biopreservation of Fish Sausage

The aim of this work was the screening of bacteriocin-producing LABs isolated from fish, the selection of promising/prominent strain(s), the characterization of the bacteriocin produced, and the evaluation of its potential to be used as biopreservative(s). Amplification and sequencing of the 16S rRNA gene of the bacteriocin-producing strain was performed. Then a partial purification of the produced bacteriocin, using a combination of ammonium sulfate and chloroform-methanol precipitation, was done. Its molecular weight was determined by SDS-PAGE. In addition, the action spectrum, the hemolysis test, and its ability to inhibit biofilm formation were analyzed. A total of 88 isolates of lactic acid bacteria (LAB) including one bacteriocin producer, which was identified as Lactococcus lactis F01, were collected. The bacteriocin was partially purified with an estimated yield of 40%. Regarding the SDS-PAGE profile, the secreted bacteriocin has molecular weight of about 3.5 kDa and was identified as class I bacteriocin. The antimicrobial test showed that the bacteriocin inhibits pathogenic and/or spoilage bacteria, 10 Gram-positive and 16 Gram-negative bacterial species. Moreover, it can inhibit biofilm formation from 1.3% (Escherichia coli) to 63.92% (Pseudomonas aeruginosa ATCC15692) depending on the strain. The hemolytic activity of novel bacteriocin was observed at the concentration of 10 μg/ml of bacteriocin crude extract, which was $0.7\pm 0.0029\%$ . In addition, it exhibited good thermal and pH stability with retained antibacterial activity of 85.25% after treatment at 121°C for 20 min, as well as at a pH range between 2.0 and 10.0. Moreover, this bacteriocin showed the ability to inhibit the growth of bacterial culture load in fish sausage stored at 8°C for 28 days. Considering the results obtained, bacteriocin could be potentially exploited as an alternative to chemical preservatives or as a substitute for antibiotics.

Emergence of a NDM-1-producing ST25 Klebsiella pneumoniae strain causing neonatal sepsis in China

Carbapenem-resistant Klebsiella pneumoniae (CRKP) seriously threaten the efficacy of modern medicine with a high associated mortality rate and unprecedented transmission rate. In this study, we isolated a clinical K. pneumoniae strain DY1928 harboring bla_NDM-1 from a neonate with blood infection. Antimicrobial susceptibility testing indicated that DY1928 was resistant to various antimicrobial agents, including meropenem, imipenem, ceftriaxone, cefotaxime, ceftazidime, cefepime, piperacillin-tazobactam, and amoxicillin-clavulanate. S1 nuclease-pulsed field gel electrophoresis (S1-PFGE), southern blot and conjugation experiment revealed that the bla_NDM-1 gene was located on a conjugative plasmid of IncA/C2 type with a 147.9 kb length. Whole-genome sequencing showed that there was a conservative structure sequence (bla_NDM-1-ble-trpF-dsbD) located downstream of the bla_NDM-1 gene. Multilocus sequence typing (MLST) classified DY1928 as ST25, which was a hypervirulent K. pneumoniae type. Phylogenetic analysis of genomic data from all ST25 K. pneumoniae strains available in the NCBI database suggested that all bla_NDM-1 positive strains were isolated in China and had clinical origins. A mouse bloodstream infection model was constructed to test the virulence of DY1928, and 11 K. pneumoniae strains homologous to DY1928 were isolated from the feces of infected mice. Moreover, we found that DY1928 had a tendency to flow from the blood into the intestine in mice and caused multiple organ damage. To our knowledge, this is the first study to report an infection caused by bla_NDM-1-positive ST25 K. pneumoniae in the neonatal unit. Our findings indicated that stricter surveillance and more effective actions were needed to reduce the risk of disseminating such K. pneumoniae strains in clinical settings, especially in neonatal wards.

Les misérables: a Parallel Between Antimicrobial Resistance and COVID-19 in Underdeveloped and Developing Countries

Purpose of Review

The COVID-19 pandemic has been responsible for more than 6.3 million deaths worldwide. During the pandemic, the indiscriminate use of antibiotics has increased, contributing to the spread of multidrug-resistant bacteria. In this review, we aim to determine the spread and impact of antibiotic treatments in patients with COVID-19, focusing on underdeveloped and developing countries.

Recent Findings

Meta-analysis revealed that bacterial co-infections and secondary infections are relatively rare in COVID-19 patients, corresponding to less than 20% of hospitalized patients. Even so, most of these patients have received antibiotic treatments.

Summary

This review discusses how the COVID-19 pandemic could increase the emergence of multidrug-resistant strains to currently available antibiotics. Initially, we discussed the spread and impact of multidrug resistance of ESKAPE pathogens associated with nosocomial infections and analyzed their risk of secondary infections in patients with COVID-19. Then we highlight three factors related to the spread of resistant bacteria during the current pandemic: overprescription of antibiotics followed by self-medication. Finally, we discussed the lack of availability of diagnostic tests to discriminate the etiologic agent of a disease. All these factors lead to inappropriate use of antibiotics and, therefore, to an increase in the prevalence of resistance, which can have devastating consequences shortly. The data compiled in this study underscore the importance of epidemiological surveillance of hospital isolates to provide new strategies for preventing and controlling infections caused by multidrug-resistant bacteria. In addition, the bibliographic research also highlights the need for an improvement in antibiotic prescribing in the health system.

Probiotics: Lactic Acid Bacteria have Antibacterial Activity and Downregulate Biofilm Genes of Uropathogenic E. coli

Urinary tract infections (UTIs) are regarded as one of the most serious infections worldwide. Uro Pathogenic E. coli (UPEC) accounts for nearly 80% of UTI infections in females. This study investigated the antibacterial and antibiofilm effects of Lactobacillus acidophilus (l. acidophilus) and Lactobacillus plantarum (lb. plantarum) on multidrug-resistant E. coli obtained from urine samples. Complete bacteriological identification was conducted on 45 E. coli isolated from 80 urine samples of females with UTIs. Antibiotic susceptibility test was performed on all isolates by nine antibiotics. Ten out of the 45 isolates exhibited multidrug resistance (MDR). L. acidophilus and Lb. plantarum showed marked inhibition of MDR E. coli isolates on agar by a diffusion method (16 ± 0.04: 23 ± 0.05 mm). Moreover, L. acidophilus and Lb. plantarum strains inhibited the ability of UPEC to form a biofilm by 56.3% and 39.63%, respectively. The expression of biofilm genes of E. coli are as follows: csgA, crl, csgD showed remarkable downregulation after treatment with probiotics suspension: 0.00364: 0.19078 fold, 0.0005: 0.1894 fold, and 0.0490: 0.0883 for L. acidophilus, respectively. On the other hand, downregulation of biofilm gene expression for csgA, crl, csgD after treatment with Lb. plantarum suspension were expressed by fold changes as follows: 0.0769: 0.3535 fold, 0.05440: 0.12940 fold, and 0.06745: 0.4146, respectively. These findings show that L. acidophilus and Lb. plantarum exhibit potent antibacterial and antibiofilm action against MDR UPEC at both genotypic and phenotypic levels, and appear to be a promising solution in therapeutic applications for recurrent and persistent UTIs.

Prevalence of the fimbrial operon mrkABCD, mrkA expression, biofilm formation and effect of biocides on biofilm formation in carbapenemase-producing Klebsiella pneumoniae isolates belonging or not to high-risk clones

BACKGROUND

The role of mrkA adhesin expression, biofilm production, biofilm viability and biocides in the biofilms of carbapenemase-producing K. pneumoniae isolates was investigated.

METHODS

Seventeen isolates representing different sequence types and carbapenemases were investigated. mrkA expression was determined by real-time RT-PCR. Biofilm production (25°C and 37°C, with and without humidity) was determined by the crystal violet assay. The effect of isopropanol, povidone-iodine, sodium hypochlorite, chlorhexidine digluconate, benzalkonium chloride, ethanol and triclosan on biofilms was determined. The effect of povidone-iodine on biofilm biomass and thickness was also determined by Confocal Laser Scanning Microscopy (CLSM).

RESULTS

mrkA expression ranged 28.2-1.3 (high or intermediate-level; 64% of HR clones) and 21.5-1.3 (50% of non-HR clones). At 25°C biofilm formation was observed in 41% of isolates (absence of humidity) and 35% of isolates (presence of humidity), whereas at 37°C it was observed in 76% of isolates, with and without humidity. At 25°C biofilm producers were more frequently observed in HR clones (45% with humidity and 55% without humidity) than non-HR clones (17% with and without humidity). Biofilm viability from day 21 was higher at 25°C than 37°C. The greatest decrease in biofilm formation was observed with povidone iodine (29% decrease), which also decrease biofilm thickness.

CONCLUSIONS

Biofilm formation in carbapenemase-producing K. pneumoniae is related to mrkA expression. Biofilm formation is affected by temperature (37°C>25°C) whereas humidity has little effect. Biofilm viability is affected by temperature (25°C>37°C). At 25°C, HR clones are more frequently biofilm producers than non-HR clones. Povidone-iodine can decrease biofilm production and biofilm thickness.

Development of the degradation bacteria in household food waste and analysis of the microbial community in aerobic composting

By screening the strains and testing different combinations of diverse bacteria, we developed a compound bacteria agent composing of 5 g Bacillus amyloliquefacien (B2), 10 g Pseudomonas aeruginosa (F4), 5 g Paenibacillus lautus (303), and 10 mL composite strains (DOD) for the degradation of household food waste (HFW). The final mass loss of HFW in aerobic composting with the compound bacteria agent B2+F4+303+DOD (group C) was 84.52%, increased by 20.83% over that loss in natural composting (group A). Analysis of 16S rRNA high-throughput sequencing showed that the phyla in the group A and the group C mainly included Firmicutes, Proteobacteria and Cyanobacteria. At the genus level, Pediococcus was the dominant genus in the group A, of which the microbial community performed better to maintain microbial system stable in the later stage of composting, while Weissella accounted for a larger proportion of the group C that acted well in reducing final mass of composting. The Ochrobactrum was closely related to the removal of odours in the early stage of the group C. The relative abundance of compound bacteria agent was always at a rather low level, suggested that it affected the composting process by changing the proportion of dominant bacteria in the compost. This article is protected by copyright. All rights reserved.

Human pandemic K27-ST392 CTX-M-15 extended-spectrum-β-lactamase-positive Klebsiella pneumoniae: A one health clone threatening companion animals

Extended spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae is a medically important pathogen that commonly causes human nosocomial infections. Since veterinary emergency and critical care services have also significantly progressed over the last decades, there are increasing reports of ESBL-producing K. pneumoniae causing hospital-associated infections in companion animals. We present microbiological and genomic analysis of a multidrug-resistant ESBL-positive K. pneumoniae (LCKp01) isolated from a fatal infection in a dog admitted to a veterinary intensive care unit. LCKp01 strain belonged to the sequence type ST392 and displays a KL27 (wzi-187) and O-locus 4 (O4). A broad resistome and presence of the bla_CTX-M-15 ESBL gene were predicted. SNP-based phylogenomic analysis, using an international genome database, clustered LCKp01 (60–80 SNPs differences) with K. pneumoniae ST392 from human and animal infections, isolated at 4-year interval, whereas phylogeographical analysis confirmed successful expansion of ST392 as a global clone of One Health concern.

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A fatal infection by a multidrug-resistant K. pneumoniae in dog was investigated.

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Identification of human pandemic K. pneumoniae ST392/CTX-M-15 clone is highlighted.

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Phylogenomic analysis revealed clonal relatedness with nosocomial lineages.

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Phylogeographical analysis confirmed expansion of ST392 as global One Health clone.

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Dissemination of K. pneumoniae ST392 at the human-animal interface is discussed.

Light-activated molecular machines are fast-acting broad-spectrum antibacterials that target the membrane

The increasing occurrence of antibiotic-resistant bacteria and the dwindling antibiotic research and development pipeline have created a pressing global health crisis. Here, we report the discovery of a distinctive antibacterial therapy that uses visible (405 nanometers) light-activated synthetic molecular machines (MMs) to kill Gram-negative and Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, in minutes, vastly outpacing conventional antibiotics. MMs also rapidly eliminate persister cells and established bacterial biofilms. The antibacterial mode of action of MMs involves physical disruption of the membrane. In addition, by permeabilizing the membrane, MMs at sublethal doses potentiate the action of conventional antibiotics. Repeated exposure to antibacterial MMs is not accompanied by resistance development. Finally, therapeutic doses of MMs mitigate mortality associated with bacterial infection in an in vivo model of burn wound infection. Visible light-activated MMs represent an unconventional antibacterial mode of action by mechanical disruption at the molecular scale, not existent in nature and to which resistance development is unlikely.

Disinfecting Action of Gaseous Ozone on OXA-48-Producing Klebsiella pneumoniae Biofilm In Vitro

Klebsiella pneumoniae is an emerging multidrug-resistant pathogen that can contaminate hospital surfaces in the form of a biofilm which is hard to remove with standard disinfectants. Because of biofilm resistance to conservative disinfectants, the application of new disinfection technologies is becoming more frequent. Ozone gas has antimicrobial activity but there is lack of data on its action against K. pneumoniae biofilm. The aim of this study was to investigate the effects and mechanisms of action of gaseous ozone on the OXA-48-procuding K. pneumoniae biofilm. A 24 h biofilm of K. pneumoniae formed on ceramic tiles was subsequently exposed to different concentrations of ozone during one and two hours to determine the optimal ozone concentration. Afterwards, the total bacteria count, total biomass and oxidative stress levels were monitored. A total of 25 ppm of gaseous ozone was determined to be optimal ozone concentration and caused reduction in total bacteria number in all strains of K. pneumoniae for 2.0 log₁₀ CFU/cm², followed by reduction in total biomass up to 88.15%. Reactive oxygen species levels significantly increased after the ozone treatment at 182% for the representative K. pneumoniae NCTC 13442 strain. Ozone gas in the concentration of 25 ppm caused significant biofilm reduction but did not completely eradicate the K. pneumoniae biofilm formed on ceramics. In conclusion, ozone gas has great potential to be used as an additional hygiene measure in joint combat against biofilm in hospital environments.

In-Human Multiyear Evolution of Carbapenem-Resistant Klebsiella pneumoniae Causing Chronic Colonization and Intermittent Urinary Tract Infections: A Case Study

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a frequent pathogen of the urinary tract, but how CRKP adapts in vivo over time is unclear. We examined 10 CRKP strains from a patient who experienced chronic colonization and recurrent urinary tract infections over a period of 4.5 years. We performed whole-genome sequencing and phenotypic assays to compare isolates that had evolved relative to the first isolate collected and to correlate genetic and phenotypic changes over time with the meropenem-containing regimen received. Phylogenetic analysis indicated that all 10 strains originated from the same sequence type 258 (ST258) clone and that three sublineages (SL) evolved over time; strains from two dominant sublineages were selected for detailed analysis. Up to 60 new mutations were acquired progressively in genes related to antibiotic resistance, cell metabolism, and biofilm production over time. Doubling of meropenem MICs, increases in biofilm production and bla_KPC expression, and altered carbon metabolism occurred in the latter strains from the last sublineage compared to the initial strain. Subinhibitory meropenem exposure in vitro significantly induced or maintained high levels of biofilm production in colonizing isolates, but isolates causing infection were unaffected. Despite acquiring different mutations that affect carbon metabolism, overall carbon utilization was maintained across different strains. Together, these data showed that isolated urinary CRKP evolved through multiple adaptations affecting carbon metabolism, carbapenem resistance, and biofilm production to support chronic colonization and intermittent urinary tract infections. Our findings highlight the pliability of CRKP in adapting to repeated antibiotic exposure and should be considered when developing novel therapeutic and stewardship strategies. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae (CRKP) can cause a variety of infections such as recurrent urinary tract infections (rUTI) with the ability to change with the host environment over time. However, it is unclear how CRKP adapts to the urinary tract during chronic infections and colonization. Here, we studied the evolution of CRKP strains from a patient who experienced chronic colonization and recurrent UTIs over a period of 4.5 years despite multiple treatment courses with meropenem-containing regimens. Our findings show the flexibility of CRKP strains in developing changes in carbapenem resistance, biofilm production, and carbon metabolism over time, which could facilitate their persistence in the human body for long periods of time in spite of repeated antibiotic therapy.

Comparison of three culture media in assessing the sensitivity of antibiotics to common foodborne microorganisms

This study aimed to determine the antibiotic susceptibility of seven antibiotics, (Amoxicillin (AX), Ampicillin (AM), Chloramphenicol (C), Ciprofloxacin (CIP), Doxycycline (DO), Gentamicin (CN) and Neomycin (N)) on some common microorganisms that cause food poisoning. Furthermore, we aimed to compare three types of culture media in assessing antibiotics susceptibility. A sensitivity test was carried out using six bacterial isolates: Micrococcus spp., Staphylococcus aureus, Escherichia coli, Salmonella spp., Proteus mirabilis, Pseudomonas aeruginosa. These bacterial isolates were identified at the Food Microbiology Division, Public Health Laboratory using three culture media: Mueller Hinton Agar (MHA), Antibiotic Assay Medium A (AAM), and nutrient agar (NA). The results showed that all of these media are suitable to test antibiotic sensitivity. Bacterial sensitivity and resistance between these media (P≤0.01) were recorded, with significant differences found at the tested probability level.

Biotyping, Virulotyping and Biofilm Formation Ability of ESBL-Klebsiella pneumoniae Isolates from Nosocomial Infections

The aim of this study was to investigate the frequency, molecular characterization, virulence genes, resistance genes and antimicrobial profile of nosocomial extended spectrum beta lactamase producing Klebsiella species. A total of 22 (12.2%) K. pneumoniae strains were isolated from 180 clinical samples collected from hospitalized patients in Egypt. K. pneumoniae biotypes were B1 (72.8%), B3 (13.6%) and B4 (13.6%). The isolates were classified for the capsular serotypes, 86.4% (20/22) were of K1 serotype, while only two isolates (13.64%) were of K2 serotype. Hypermucoviscous K. pneumoniae isolates accounted for 68.2%. Biofilm formation ability of K. pneumoniae was determined by microtitre plate method. The majority of the isolates (40.9%) were moderate biofilm producers, while 27.3% were strong biofilm producers. All K. pneumoniae strains were positive for fimH and traT genes, while magA was identified in only 63.6% of the isolates. The antibiotic susceptibility profile of the isolates (n=22) was determined by the disc diffusion technique using 23 different antibiotics. Streptomycin and imipenem are the most effective antibiotics against 22 tested K. pneumoniae isolates with sensitivity rates of 63.64% and 54.54%, respectively. All tested K. pneumoniae isolates showed high resistance to amoxicillin∕clavulanate (100%), cefuroxime (100%) and ceftazidime (95.45%). Extended spectrum beta lactamases (ESBL) production and the presence of ESBL related genes were tested in the isolates. All the isolates tested positive for blaVIM, NDM1, and blaTEM, while only 81.8 percent tested positive for the blaSHV gene. Increasing antimicrobial resistance in K. pneumoniae causing nosocomial infections limits the use of antimicrobial agents for treatment. Furthermore, the spread of biofilm, multiple drug resistant and ESBL-producing K. pneumoniae isolates is a public threat for hospitalized patients.

Antimicrobial Peptides as an Alternative for the Eradication of Bacterial Biofilms of Multi-Drug Resistant Bacteria

Bacterial resistance is an emergency public health problem worldwide, compounded by the ability of bacteria to form biofilms, mainly in seriously ill hospitalized patients. The World Health Organization has published a list of priority bacteria that should be studied and, in turn, has encouraged the development of new drugs. Herein, we explain the importance of studying new molecules such as antimicrobial peptides (AMPs) with potential against multi-drug resistant (MDR) and extensively drug-resistant (XDR) bacteria and focus on the inhibition of biofilm formation. This review describes the main causes of antimicrobial resistance and biofilm formation, as well as the main and potential AMP applications against these bacteria. Our results suggest that the new biomacromolecules to be discovered and studied should focus on this group of dangerous and highly infectious bacteria. Alternative molecules such as AMPs could contribute to eradicating biofilm proliferation by MDR/XDR bacteria; this is a challenging undertaking with promising prospects.

Modular 3D-Printed Peg Biofilm Device for Flexible Setup of Surface-Related Biofilm Studies

Medical device-related biofilms are a major cause of hospital-acquired infections, especially chronic infections. Numerous diverse models to study surface-associated biofilms have been developed; however, their usability varies. Often, a simple method is desired without sacrificing throughput and biological relevance. Here, we present an in-house developed 3D-printed device (FlexiPeg) for biofilm growth, conceptually similar to the Calgary Biofilm device but aimed at increasing ease of use and versatility. Our device is modular with the lid and pegs as separate units, enabling flexible assembly with up- or down-scaling depending on the aims of the study. It also allows easy handling of individual pegs, especially when disruption of biofilm populations is needed for downstream analysis. The pegs can be printed in, or coated with, different materials to create surfaces relevant to the study of interest. We experimentally validated the use of the device by exploring the biofilms formed by clinical strains of Escherichia coli and Klebsiella pneumoniae, commonly associated with device-related infections. The biofilms were characterized by viable cell counts, biomass staining, and scanning electron microscopy (SEM) imaging. We evaluated the effects of different additive manufacturing technologies, 3D printing resins, and coatings with, for example, silicone, to mimic a medical device surface. The biofilms formed on our custom-made pegs could be clearly distinguished based on species or strain across all performed assays, and they corresponded well with observations made in other models and clinical settings, for example, on urinary catheters. Overall, our biofilm device is a robust, easy-to-use, and relevant assay, suitable for a wide range of applications in surface-associated biofilm studies, including materials testing, screening for biofilm formation capacity, and antibiotic susceptibility testing.

Biofilm Formation and Associated Gene Expression in Multidrug-Resistant Klebsiella pneumoniae Isolated from Clinical Specimens

Biofilms reduce the bacterial growth rate, inhibit antibiotic penetration, lead to the development of persister cells and facilitate genetic exchange. The biofilm-associated Klebsiella pneumoniae infections have not been well studied, and their implications in overcoming the effects of antimicrobial therapy are yet to be fully understood. Hence this study evaluated the antibiotic resistance pattern, antibiotic resistance determinants of extended-spectrum beta-lactamase (ESBL) family. Biofilm-forming ability of seventy multidrug-resistant clinical isolates of K. pneumoniae and the biofilm-associated genes of representative biofilm formers from a tertiary care hospital were also assessed. The K. pneumoniae isolated from urine exhibited resistance towards ceftazidime, nalidixic acid and meropenem. Isolates from blood were resistant to cefuroxime. Higher rates of resistance were observed towards cefuroxime, nalidixic acid, and meropenem for the isolates from the endotracheal aspirate. Extended spectrum beta-lactamase production by CLSI's disc diffusion-based confirmation test revealed all the K. pneumoniae to be as ESBL producers. Most of the isolates harboured the bla gene variants, bla_SHV and bla_TEM. Majority of the isolates were colistin sensitive. 97.1% of the K. pneumoniae produced biofilm. K. pneumoniae isolated from pus and blood produced fully established biofilms. Strong biofilm formers were sensitive to co-trimoxazole and ciprofloxacin. Moderate biofilm formers exhibited sensitivity towards meropenem and imipenem. Expression of the fimH gene was increased, while mrkD showed reduced expression among the strong biofilm formers. Moderate biofilm formers showed variable expression of the genes associated with the biofilm formation. The weak and non-biofilm formers showed reduced expression of both the fimbrial genes. Multidrug-resistant isolates produced ESBLs and formed well-established biofilms.

Exploring Klebsiella pneumoniae capsule polysaccharide proteins to design multiepitope subunit vaccine to fight against pneumonia

BACKGROUND

Klebsiella pneumoniae is an emerging human pathogen causing neonatal lung disease, catheter-associated infections, and nosocomial outbreaks with high fatality rates. Capsular polysaccharide (CPS) protein plays a major determinant in virulence and is considered as a promising target for vaccine development.

RESEARCH DESIGN AND METHODS

In this study, we used immunoinformatic approaches to design a multi-peptide vaccine against K. pneumonia. The epitopes were selected through several immune filters, such as antigenicity, conservancy, nontoxicity, non-allergenicity, binding affinity to HLA alleles, overlapping epitopes, and peptides having common epitopes.

RESULTS

Finally, a construct comprising 2 B-Cell, 8 CTL, 2 HTL epitopes, along with adjuvant, linkers was designed. Peptide-HLA interaction analysis showed strong binding of these epitopes with several common HLA molecules. The in silico immune simulation and population coverage analysis of the vaccine showed its potential to evoke strong immune responses.. Further, the interaction between vaccine and immune was evaluated by docking and simulation, revealing high affinity and complex stability. Codon adaptation and in silico cloning revealed higher expression of vaccine in E. coli K12 expression system.

CONCLUSIONS

Conclusively, the findings of the present study suggest that the designed novel multi-epitopic vaccine holds potential for further experimental validation against the pathogen.

Computational design and characterization of a multiepitope vaccine against carbapenemase-producing Klebsiella pneumoniae strains, derived from antigens identified through reverse vaccinology

Klebsiella pneumoniae is a Gram-negative pathogen of clinical relevance, which can provoke serious urinary and blood infections and pneumonia. This bacterium is a major public health threat due to its resistance to several antibiotic classes. Using a reverse vaccinology approach, 7 potential antigens were identified, of which 4 were present in most of the sequences of Italian carbapenem-resistant K. pneumoniae clinical isolates. Bioinformatics tools demonstrated the antigenic potential of these bacterial proteins and allowed for the identification of T and B cell epitopes. This led to a rational design and in silico characterization of a multiepitope vaccine against carbapenem-resistant K. pneumoniae strains. As adjuvant, the mycobacterial heparin-binding hemagglutinin adhesin (HBHA), which is a Toll-like receptor 4 (TLR-4) agonist, was included, to increase the immunogenicity of the construct. The multiepitope vaccine candidate was analyzed by bioinformatics tools to assess its antigenicity, solubility, allergenicity, toxicity, physical and chemical parameters, and secondary and tertiary structures. Molecular docking binding energies to TLR-2 and TLR-4, two important innate immunity receptors involved in the immune response against K. pneumoniae infections, and molecular dynamics simulations of such complexes supported active interactions. A codon optimized multiepitope sequence cloning strategy is proposed, for production of recombinant vaccine in classical bacterial vectors. Finally, a 3 dose-immunization simulation with the multiepitope construct induced both cellular and humoral immune responses. These results suggest that this multiepitope construct has potential as a vaccination strategy against carbapenem-resistant K. pneumoniae and deserves further validation.