Association of Antibiotic Resistance, Cell Adherence, and Biofilm Production with the Endemicity of Nosocomial Klebsiella pneumoniae

Comparative genomic analyses of Klebsiella pneumoniae K57 capsule serotypes isolated from bovine mastitis in China

Klebsiella pneumoniae can cause severe clinical mastitis in dairy cows, with K. pneumoniae type K57 (K57-KP) being the most common capsular serotype. To identify virulence factors and antimicrobial-resistance (AMR) genes of K57-KP with varying virulence, Galleria mellonella (greater wax moth) larvae were infected as a screening model to characterize virulence of 90 K57-KP strains, with 10 and 11 strains defined as virulent or attenuated, respectively, based on larval survival rates. Next, virulence of these 21 isolates was subsequently confirmed in adhesion and lactate dehydrogenase release assays, using bovine mammary epithelial cells cultured in vitro. Finally, genes associated with virulence and AMR were characterize with whole-genome sequencing. These 21 K57-KP strains were designated into 16 sequence types based on multi-locus sequence typing and allocated in phylogenetic analysis based on single nucleotide polymorphisms. We found great genetic diversity among isolates. In addition, adhesion-associated genes (e.g., fimA, sfaA, and focA) aminoglycoside-resistance genes (aph(6)-Id, strAB) were associated with virulence. This study provided new knowledge regarding virulence of K57-KP associated with bovine mastitis, which may inform development of novel diagnostic tools and prevention strategies for bovine mastitis.

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.

Novel Antibacterial Agents SAAP-148 and Halicin Combat Gram-Negative Bacteria Colonizing Catheters

The antibiotic management of catheter-related infections (CRIs) often fails owing to the emergence of antimicrobial-resistant strains and/or biofilm/persister apparitions. Thus, we investigated the efficacy of two novel antimicrobial agents, i.e., the synthetic peptide SAAP-148 and the novel antibiotic halicin, against Gram-negative bacteria (GNB) colonizing catheters. The antibacterial, anti-biofilm, and anti-persister activities of both agents were evaluated against Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae strains. The enrolled strains were isolated from catheters and selected based on their resistance to at least three antibiotic classes and biofilm formation potential. Furthermore, the hemolysis and endotoxin neutralization abilities of these agents were explored. The bactericidal activity of both agents was reduced in urine and plasma as compared to buffered saline. In a dose-dependent manner, SAAP-148 and halicin reduced bacterial counts in 24 h preformed biofilms on silicone elastomer discs and eliminated persisters originating from antibiotic-exposed mature 7-day biofilms, with halicin being less effective than SAAP-148. Importantly, SAAP-148 and halicin acted synergistically on E. coli and K. pneumoniae biofilms but not on A. baumannii biofilms. The peptide, but not halicin, decreased the production of IL-12p40 upon exposure to UV-killed bacteria. This preliminary study showed that SAAP-148 and halicin alone/in combination are promising candidates to fight GNB colonizing catheters.

ESKAPEE pathogens newly released from biofilm residence by a targeted monoclonal are sensitized to killing by traditional antibiotics

Introduction

The "silent" antimicrobial resistance (AMR) pandemic is responsible for nearly five million deaths annually, with a group of seven biofilm-forming pathogens, known as the ESKAPEE pathogens, responsible for 70% of these fatalities. Biofilm-resident bacteria, as they exist within the disease site, are canonically highly resistant to antibiotics. One strategy to counter AMR and improve disease resolution involves developing methods to disrupt biofilms. These methods aim to release bacteria from the protective biofilm matrix to facilitate their killing by antibiotics or immune effectors. Several laboratories working on such strategies have demonstrated that bacteria newly released from a biofilm display a transient phenotype of significantly increased susceptibility to antibiotics. Similarly, we developed an antibody-based approach for biofilm disruption directed against the two-membered DNABII family of bacterial DNA-binding proteins, which serve as linchpins to stabilize the biofilm matrix. The incubation of biofilms with α-DNABII antibodies rapidly collapses them to induce a population of newly released bacteria (NRel).

Methods

In this study, we used a humanized monoclonal antibody (HuTipMab) directed against protective epitopes of a DNABII protein to determine if we could disrupt biofilms formed by the high-priority ESKAPEE pathogens as visualized by confocal laser scanning microscopy (CLSM) and COMSTAT2 analysis. Then, we demonstrated the potentiated killing of the induced NRel by seven diverse classes of traditional antibiotics by comparative plate count.

Results

To this end, ESKAPEE biofilms were disrupted by 50%-79% using a single tested dose and treatment period with HuTipMab. The NRel of each biofilm were significantly more sensitive to killing than their planktonically grown counterparts (heretofore, considered to be the most sensitive to antibiotic-mediated killing), even when tested at a fraction of the MIC (1/250-1/2 MIC). Moreover, the bacteria that remained within the biofilms of two representative ESKAPEE pathogens after HuTipMab disruption were also significantly more susceptible to killing by antibiotics.

Discussion

New data presented in this study support our continued development of a combinatorial therapy wherein HuTipMab is delivered to a patient with recalcitrant disease due to an ESKAPEE pathogen to disrupt a pathogenic biofilm, along with a co-delivered dose of an antibiotic whose ability to rapidly kill the induced NRel has been demonstrated. This novel regimen could provide a more successful clinical outcome to those with chronic, recurrent, or recalcitrant diseases, while limiting further contribution to AMR.

Antimicrobial activity in Asterceae: The selected genera characterization and against multidrug resistance bacteria

Plants from the Asteraceae family are widely used as ethno medicines to treatment parasitic, malaria, hematemesis, pruritus, pyretic, anthelmintic, wound healing. The aim of this review is to provide an overview of Asteraceae plants antimicrobial activity. The most relevant results from the published studies are summarized and discussed. The species in genus of Artemisia, Echinacea, Centaurea, Baccharis, and Calendula showed antimicrobial activity. Most of these species are usually used as ethno medicines to treat infection, inflammation, and parasitics. The effective part or component for antimicrobial was essential oil and crude extract, and essential oil attracted more attention. It was also reported that nanoparticles coated with crude extract were effective against multidrug resistant bacteria. For multidrug resistant bacteria study, the species in Armtemisia were the most investigated, and Staphylococcus aureus and Escherichia coli were the most studied multidrug resistant strains. The antimicrobial activity was evaluated mainly based on the results of minimum inhibitory concentration (MIC). Few reports have been reported on minimum bactericide concentration (MBC) and its antibacterial mechanisms. According to the reported study results, some plants in Asteraceae have the potential to be developed as bacteriostatic agents and against multidrug resistant bacteria. However, most studies are still in vitro, further clinical and applied studies are needed.

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.

Genome-wide association study of Klebsiella pneumoniae identifies variations linked to carbapenems resistance

Klebsiella pneumoniae (KP) is one of the microorganisms that can acquire carbapenem-resistance (CR), and few antimicrobial therapy options exist for infections caused by Carbapenem-Resistant KP (CRKP). In recent years, with the increase of carbapenem resistance rates, treating CRKP has become a serious public health threat in clinical practice. We have collected 2,035 clinical KP isolates from a tertiary hospital in China. Whole genome sequencing data coupled with their binary antimicrobial susceptibility testing data were obtained to conduct the genome-wide association study using a bayesian-based method, including single nucleotide polymorphisms (SNPs) and genes. We identified 28 and 37 potential maker genes associated with imipenem and meropenem resistance, respectively. Among which 19 of them were selected in both drugs by genome-wide association study (GWAS), 11 genes among them were simultaneously validated in independent datasets. These genes were likely related to biofilm formation, efflux pump, and DNA repairing. Moreover, we identified 13 significant CR related SNPs in imipenem or meropenem, with one SNP located in the non-coding region and validated in the independent datasets. Our study indicates complex mechanisms of carbapenems resistance and further investigation of CRKP-related factors are warranted to better understand their contributions to carbapenems resistance. These identified biomarkers may provide targets for future drug interventions or treatments.

CTX-M-producing Escherichia coli strains: resistance to temocillin, fosfomycin, nitrofurantoin and biofilm formation

Aim: ESBL-producing and bacterial biofilms-forming Escherichia coli are associated with antimicrobial treatment failure. This study aimed to investigate the phenotypic resistance mechanisms of CTX-M E. coli against old antibiotics - cell wall synthesis inhibitors temocillin, nitrofurantoin and fosfomycin. Materials & Methods: Susceptibility to old antibiotics testing was performed using disk diffusion method, biofilm formation was evaluated spectrophotometrically, and PCR was used for the determination of CTX-M type. Results & conclusion: Temocillin was active against nearly 93%, nitrofurantoin and fosfomycin, respectively, 91.7% and 98.6% of tested E. coli. Thus, it demonstrated to be a good alternative therapeutic option against ESBL infections. Bacteria resistant to old antibiotics had CTX-M-15 or CTX-M-15, TEM-1 and OXA-1 combinations. No significant association was found between CTX-M E. coli resistance to temocillin, nitrofurantoin and fosfomycin; however, the level of biofilm formation was found as not affected by the type of CTX-M β-lactamases.

Whole genome sequencing of Klebsiella pneumoniae clinical isolates sequence type 627 isolated from Egyptian patients

Klebsiella pneumoniae is considered a threat to public health especially due to multidrug resistance emergence. It is largely oligoclonal based on multi-locus sequence typing (MLST); in Egypt, ST 627 was recently detected. Despites the global dissemination of this ST, there is still paucity of information about it. Herein, we used 4 K. pneumoniae ST627 for whole genome sequencing utilizing an Illumina MiSeq platform. Genome sequences were examined for resistance and virulence determinants, capsular types, plasmids, insertion sequences, phage regions, and Clustered Regularly Interspaced Palindromic Repeats (CRISPR) regions using bioinformatic analysis. The molecular characterization revealed 15 and 65 antimicrobial resistance and virulence genes, respectively. Resistance genes such as tet(D), aph(3’’)-Ib, aph(6)-Id, blaTEM-234, fosA, and fosA6; were mainly responsible for tetracycline, aminoglycoside, and fosfomycin resistance; respectively. The capsular typing revealed that the four strains are KL-24 and O1v1. One plasmid was found in all samples known as pC17KP0052-1 and another plasmid with accession no. NZ_CP032191.1 was found only in K90. IncFIB(K) and IncFII(K) are two replicons found in all samples, while ColRNAI replicon was found only in K90. Entero P88, Salmon SEN5, and Klebsi phiKO2 intact phage regions were identified. All samples harbored CRISPR arrays including CRISPR1 and CRISPR2. Our results shed light on critical tasks of mobile genetic elements in ST 627 in antibiotic resistance spreading.

Antimicrobial Resistance and Virulence Characteristics of Klebsiella pneumoniae Isolates in Kenya by Whole-Genome Sequencing

Klebsiella pneumoniae is a globally significant opportunistic pathogen causing healthcare-associated and community-acquired infections. This study examined the epidemiology and the distribution of resistance and virulence genes in clinical K. pneumoniae strains in Kenya. A total of 89 K. pneumoniae isolates were collected over six years from five counties in Kenya and were analyzed using whole-genome sequencing and bioinformatics. These isolates were obtained from community-acquired (62/89) and healthcare-associated infections (21/89), and from the hospital environment (6/89). Genetic analysis revealed the presence of blaNDM-1 and blaOXA-181 carbapenemase genes and the armA and rmtF genes known to confer pan-aminoglycoside resistance. The most abundant extended-spectrum beta-lactamase genes identified were blaCTX-M-15 (36/89), blaTEM (35/89), and blaOXA (18/89). In addition, one isolate had a mobile colistin resistance gene (mcr-8). Fluoroquinolone resistance-conferring mutations in gyrA and parC genes were also observed. The most notable virulence factors were those associated with hyper-virulence (rmpA/A2 and magA), yersiniabactin (ybt), salmochelin (iro), and aerobactin (iuc and iutA). A total of 38 distinct sequence types were identified, including known global lineages ST14, ST15, ST147, and ST307, and a regional clone ST17 implicated in regional outbreaks. In addition, this study genetically characterized two potential hypervirulent isolates and two community-acquired ST147 high-risk clones that contained carbapenemase genes, yersiniabactin, and other multidrug resistance genes. These results demonstrate that the resistome and virulome of Kenyan clinical and hospital environmental K. pneumoniae isolates are diverse. The reservoir of high-risk clones capable of spreading resistance, and virulence factors have the potential to cause unmanageable infection outbreaks with high morbidity and mortality.

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.

Global Prevalence of Nosocomial Multidrug-Resistant Klebsiella pneumoniae: A Systematic Review and Meta-Analysis

The emergence of nosocomial multidrug-resistant Klebsiella pneumoniae is an escalating public health threat worldwide. The prevalence of nosocomial infections due to K. pneumoniae was recorded up to 10%. In this systematic review and meta-analysis, which were conducted according to the guidelines of Preferred Reporting Items for Systematic Review and Meta-Analysis, 1092 articles were screened from four databases of which 47 studies fulfilled the selected criteria. By performing a random-effect model, the pooled prevalence of nosocomial multidrug-resistant K. pneumoniae was estimated at 32.8% (95% CI, 23.6-43.6), with high heterogeneity (I2 98.29%, p-value < 0.001). The estimated prevalence of this pathogen and a few related studies were discussed, raising awareness of the spread of multidrug-resistant K. pneumoniae in the healthcare setting. The emergence of nosocomial multidrug-resistant K. pneumoniae is expected to increase globally in the future, and the best treatments for treating and preventing this pathogen should be acknowledged by healthcare staff.

Antibacterial and antibiofilm efficacy of Ag NPs, Ni NPs and Al2O3 NPs singly and in combination against multidrug-resistant Klebsiella pneumoniae isolates

BACKGROUND

Although traditional antibiotic therapy provided an effective approach to combat pathogenic bacteria, the long-term and widespread use of antibiotic results in the evolution of multidrug-resistant bacteria. Recent progress in nanotechnology offers an alternative opportunity to discover and develop novel antibacterial agents.

METHODS

A total of 51 K. pneumoniae strains were collected from several specimens of hospitalized patients and identified by two parallel methods (biochemical tests and Vitek-2 system). The antibiotic sensitivity of isolates was evaluated by disk diffusion antibiogram and Vitek-2 system. The biofilms formation ability of antibiotic-resistant strains was examined by microtiter plate and tube methods based on crystal violet staining. The molecular technique was used to determine key genes responsible for biofilms formation of clinical isolates. The antibacterial and antibiofilm activities of Ag NPs, Ni NPs, Al₂O₃ NPs singly (NPs) and in combination (cNPs) were investigated against selected strains using standard methods. Moreover, the cytotoxicity of NPs was evaluated on mouse neural crest-derived (Neuro-2A) cell line.

RESULTS

The results of bacterial studies revealed that more than 80 % of the isolates were resistant to commonly used antibiotics and about 95 % of them were able to form biofilms. Moreover, the presence of fimA and mrkA genes were determined in all biofilm-producing strains. The results of antibacterial and antibiofilm activities of NPs and cNPs demonstrated the lower MIC and MBEC values for Al₂O₃ NPs singly as well as for Ag/Ni cNPs and Ag/Al₂O₃ cNPs in combination, respectively. Overall, the inhibitory effects of cNPs were superior to NPs against all strains. Furthermore, the results of the checkerboard assays showed that Ag NPs act synergistically with two other NPs against multidrug-resistant Klebsiella pneumoniae (MDR-K. pneumoniae) isolates. The in vitro cytotoxicity assay revealed no significant toxicity of NPs against Neuro-2A cells.

CONCLUSION

In the present study, the combination of Ag NPs, Ni NPs, and Al₂O₃ NPs were used against MDR-K. pneumoniae strains and antibacterial and antibiofilm activities were observed for Ag/Ni cNPs and Ag/Al₂O₃ cNPs.

Biofilm Formation of Clinical Klebsiella pneumoniae Strains Isolated from Tracheostomy Tubes and Their Association with Antimicrobial Resistance, Virulence and Genetic Diversity

(1) Background: Due to the commonness of tracheotomy procedures and the wide use of biomaterials in the form of tracheostomy tubes (TTs), the problem of biomaterial-associated infections (BAIs) is growing. Bacterial colonization of TTs results in the development of biofilms on the surface of biomaterials, which may contribute to the development of invasive infections in tracheostomized patients. (2) Methods: Clinical strains of K. pneumoniae, isolated from TTs, were characterized according to their ability to form biofilms, as well as their resistance to antibiotics, whether they harbored ESβL genes, the presence of selected virulence factors and genetic diversity. (3) Results: From 53 patients, K. pneumoniae were detected in 18 of the TTs examined, which constituted 34% of all analyzed biomaterials. Three of the strains (11%) were ESβL producers and all had genes encoding CTX-M-1, SHV and TEM enzymes. 44.4% of isolates were biofilm formers, SEM demonstrating that K. pneumoniae formed differential biofilms on the surface of polyethylene (PE) and polyvinyl chloride (PVC) TTs in vitro. A large range of variation in the share of fimbrial genes was observed. PFGE revealed sixteen genetically distinct profiles. (4) Conclusions: Proven susceptibility of TT biomaterials to colonization by K. pneumoniae means that the attention of research groups should be focused on achieving a better understanding of the bacterial pathogens that form biofilms on the surfaces of TTs. In addition, research efforts should be directed at the development of new biomaterials or the modification of existing materials, in order to prevent bacterial adhesion to their surfaces.

Association between biofilm-production and antibiotic resistance in Escherichia coli isolates: A laboratory-based case study and a literature review

Bacteria can enhance their survival by attaching to inanimate surfaces or tissues, and presenting as multicellular communities encased in a protective extracellular matrix called biofilm. There has been pronounced interest in assessing the relationship between the antibiotic resistant phenotype and biofilm-production in clinically-relevant pathogens. The aim of the present paper was to provide additional experimental results on the topic, testing the biofilm-forming capacity of Escherichia coli isolates using in vitro methods in the context of their antibiotic resistance in the form of a laboratory case study, in addition to provide a comprehensive review of the subject. In our case study, a total of two hundred and fifty (n = 250) E. coli isolates, originating from either clean-catch urine samples (n = 125) or invasive samples (n = 125) were included. The colony morphology of isolates were recorded after 24h, while antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method. Biofilm-formation of the isolates was assessed with the crystal violet tube-adherence method. Altogether 57 isolates (22.8%) isolates were multidrug resistant (MDR), 89 isolates (35.6%) produced large colonies (>3 mm), mucoid variant colonies were produced in 131 cases (52.4%), and 108 (43.2%) were positive for biofilm formation. Biofilm-producers were less common among isolates resistant to third-generation cephalosporins and trimethoprim-sulfamethoxazole (P = 0.043 and P = 0.023, respectively). Biofilms facilitate a protective growth strategy in bacteria, ensuring safety against environmental stressors, components of the immune system and noxious chemical agents. Being an integral part of bacterial physiology, biofilm-formation is interdependent with the expression of other virulence factors (especially adhesins) and quorum sensing signal molecules. More research is required to allow for the full understanding of the interplay between the MDR phenotype and biofilm-production, which will facilitate the development of novel therapeutic strategies.

Analysis of antibiotic resistance and virulence patterns in Klebsiella pneumoniae isolated from human urinary tract infections in India

In this study, 504 urine samples collected from patients suffering from urinary tract infection (UTIs) were screened for the presence of Klebsiella pneumoniae. The overall occurrence of Klebsiella spp. and K. pneumoniae was found to be 23·2% (117/504) and 16·8% (85/504) respectively. Antibiotic susceptibility testing of 85 K. pneumoniae isolates was carried out by disc diffusion which revealed alarming levels of antibiotic resistance (ABR). Antimicrobial resistance was prominently observed against cefpodoxime (76·47%) followed by ampicillin (70·59%), ceftriaxone (52·94%), cefoxitin (50·59%), amoxyclav (48·24%), ofloxacin (45·88%), cefotaxime (44·71%), cefepime (43·53%) and doxycycline hydrochloride (40%). A small percentage of strains also exhibited resistance to other antimicrobials in the range of 7-35%. Around 77·6% of the isolates were found to be resistant to three or more antibiotic classes and 66·7% of the isolates had multiple antibiotic resistance index values >0·2. Screening of virulence genes in 85 K. pneumoniae isolates revealed that uge gene was the most predominant (11/85, 12·9%), followed by rmpA (9/85, 10·5%), kfu (4/85, 4·7%) and aerobactin genes (2/85, 2·35%). Further, the overall percentage of biofilm producers were found to be 17·65% (15/85). This study warrants hospitals and health care centres to reduce misuse of antibiotics and manage UTI with appropriate treatment after performing antibiotic susceptibility testing.

Molecular Characterization and Survive Abilities of Salmonella Heidelberg Strains of Poultry Origin in Brazil

The aim of the study was to evaluate the genotypic and phenotypic characteristics of 20 strains of S. Heidelberg (SH) isolated from broilers produced in southern Brazil. The similarity and presence of genetic determinants linked to virulence, antimicrobial resistance, biofilm formation, and in silico-predicted metabolic interactions revealed this serovar as a threat to public health. The presence of the ompC, invA, sodC, avrA, lpfA, and agfA genes was detected in 100% of the strains and the luxS gene in 70% of them. None of the strains carries the bla_SHV, mcr-1, qnrA, qnrB, and qnrS genes. All strains showed a multidrug-resistant profile to at least three non-β-lactam drugs, which include colistin, sulfamethoxazole, and tetracycline. Resistance to penicillin, ceftriaxone (90%), meropenem (25%), and cefoxitin (25%) were associated with the presence of bla_CTX–M and bla_CMY–2 genes. Biofilm formation reached a mature stage at 25 and 37°C, especially with chicken juice (CJ) addition. The sodium hypochlorite 1% was the least efficient in controlling the sessile cells. Genomic analysis of two strains identified more than 100 virulence genes and the presence of resistance to 24 classes of antibiotics correlated to phenotypic tests. Protein-protein interaction (PPI) prediction shows two metabolic pathways correlation with biofilm formation. Virulence, resistance, and biofilm determinants must be constant monitoring in SH, due to the possibility of occurring infections extremely difficult to cure and due risk of the maintenance of the bacterium in production environments.

Characterization of Multidrug-Resistant Biofilm-Producing Escherichia coli and Klebsiella pneumoniae in Healthy Cattle and Cattle with Diarrhea

This study describes comparative occurrence and characterization of multidrug-resistant (MDR) Escherichia coli and Klebsiella pneumoniae (KP) in healthy cattle (HC) and cattle with diarrhea (DC) in India. During 2018-2020, 72 MDR isolates, including 35 E. coli (DC: 27; HC 8) and 37 K. pneumoniae (DC: 34; HC: 3), from 251 rectal swabs (DC: 219; HC: 32) were investigated for extended-spectrum beta-lactamase (ESBL), AmpC type β-lactamase and carbapenemase production, antimicrobial susceptibility profile, biofilm production, and efflux pump activity. Fifty-five MDR isolates were ESBL producers (ESBLPs) (DC: 50; HC: 5) and ESBLPs from DC were coresistant to multiple antibiotics. The blaCTX-M gene (50) was the most frequently detected β-lactamases followed by blaAmpC (22), blaTEM1 (13), blaCMY-6 (6), blaOXA1 (5), blaPER (2), blaDHA, and blaFOX and blaSHV12 (1 each). Plasmid-mediated quinolone resistance determinants qnrB, qnrS, qnrA, and qepA were detected in 18, 16, 2, and 3 isolates, respectively. Twenty three isolates revealed mutation in gyrA and parC genes. Tetracycline-resistance markers tetA, tetB, tetC, and tetE were detected in 33, 10, 3, and 2 isolates, respectively. Only one of the 41 imipenem-resistant isolates harbored blaNDM-5 and two were colistin-resistant. Altogether, 20 MDR isolates were strong biofilm producers and 19 harbored different virulence factors. This is the first ever report from India on the presence of MDR Enterobacteriaceae with resistance to even last-resort antimicrobials in the bovine diarrhea.

Comparative genomics with a multidrug-resistant Klebsiella pneumoniae isolate reveals the panorama of unexplored diversity in Northeast Brazil

The emergence of community acquired infections increases the public health concern on K. pneumoniae and closely related bacteria among which antimicrobial resistance spreads. We report a multidrug-resistant K. pneumoniae isolate, B31, of a patient infected in the community and admitted to an intensive care unit in Northeast Brazil. Antimicrobial susceptibility and genome information were thoroughly investigated to characterize B31 in front of 172 sequenced strains of different countries. Assigned to the Sequence Type 15, which is globally spread, B31 presented extended spectrum beta-lactamase, tigecycline and ciprofloxacin resistance. Genome sequencing revealed most resistance genes being carried by plasmids with high dissemination potential. The absence of main virulence factors, like yersiniabactin and colibactin, apparently suggests a mild pathogenic strain which, on the contrary, persisted and caused severe infection in a previously healthy patient. The present study contributes to unveil the unclear genomic scenario of virulent and multidrug-resistant K. pneumoniae in Brazil.

Graphene Oxide Coatings as Tools to Prevent Microbial Biofilm Formation on Medical Device

The clinical challenge on surface engineering of medical devices to prevent microorganisms adhesion and biofilm formation, has become an essential aspect for medical implants. Antibacterial properties of Graphene Oxide (GO) have been demonstrated across a broad spectrum of bacteria, and the different mechanisms of action with which this nanomaterial interacts with the microbial surface have been elucidated in detail. Innovative protective coatings based on graphene film and hydrogel could represent an innovative solution for the prevention of nosocomial pathogens colonization on implantable device. This brief review mainly focuses on the applications of graphene in nanomedicine with a particular deepening on the antibacterial properties of GO and GO-based nanomaterials. In order to evaluate the possible future applications of GO as an anti-biofilm coating material for medical devices, studies on the ability of graphene coated surface to prevent microbial adhesion are also discussed. A concise review on in vitro toxicity and in vivo safety is also presented.

Genotypic characterisation and antimicrobial resistance of Pseudomonas aeruginosa strains isolated from patients of different hospitals and medical centres in Poland

Background

Pseudomonas aeruginosa is a Gram-negative bacteria responsible for infections in immunocompromised patients and is one of the most common causes of nosocomial infections particularly in intensive care and burn units. We aimed to investigate the population structure of P. aeruginosa strains isolated from patients at different hospital wards. Methods: We analysed the possible presence of P. aeruginosa epidemic or endemic strains in hospitals of the selected region. A genotyping analysis was performed for P. aeruginosa isolates (n = 202) collected from patients of eleven hospitals in north-western Poland. Collections of P. aeruginosa were genotyped using pulsed-field gel electrophoresis (PFGE). Phenotypic screening for antibiotic susceptibility was performed for the common antimicrobial agents.

Results

Pseudomonas aeruginosa isolates were distributed among 116 different pulsotype groups. We identified 30 groups of clonally related strains, each containing from 2 to 17 isolates and typed the obtained 13 unique patterns, designated as A, D, E, J, K, M, N, Ó, P, T, X, AC, AD, and AH. The two largest clusters, D and E, contained 17 and 13 isolates, respectively. Strains of these groups were continuously isolated from patients at intensive care units and burn units, indicating transmission of these strains.

Conclusions

In this study, we demonstrate the clonal relatedness of P. aeruginosa strains and their constant exchange in hospitals over a period of 15 months. The obtained results indicate a predominantly non-clonal structure of P. aeruginosa.

Antibacterial, anti-efflux, anti-biofilm, anti-slime (exopolysaccharide) production and urease inhibitory efficacies of novel synthesized gold nanoparticles coated Anthemis atropatana extract against multidrug- resistant Klebsiella pneumoniae strains

In this study, the antibacterial, anti-efflux, anti-biofilm, anti-slime (exopolysaccharide) production and urease inhibitory efficacies of green synthesized gold nanoparticles (AuNPs) coated Anthemis atropatana extract against multidrug- resistant (MDR) Klebsiella pneumoniae strains were evaluated. The green synthesized AuNPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffractometer (XRD), particle size distribution, zeta potential and Fourier-transform infrared spectroscopy (FTIR). Then, antibacterial, anti-slime (exopolysaccharide) production, anti-biofilm and anti-efflux activities of AuNPs were investigated using micro-dilation, Congored agar, microtiter plate and MIC of ethidium bromide methods, respectively. Subsequently, the expression of mrkA, wzm and acrB genes was evaluated using quantitative Real-Time PCR (qRT-PCR). The synthesized AuNPs exhibited antibacterial activity against MDR strains of K. pneumoniae (minimum inhibitory concentration (MIC) of 6.25-50 µg/ml), as well as showed significant anti-slime (exopolysaccharide) production, anti-biofilm and anti-efflux activities against MDR strains. AuNPs showed significant inhibition against jack-bean urease and down-regulated the expression of mrkA, wzm and acrB genes. Moreover, the in vitro cytotoxic activity confirmed by MTT assay on the HEK-293 normal cell line showed negligible cytotoxicity. Thus, the present study suggests the potential use of AuNPs in the development of novel therapeutics for the prevention of biofilm-associated K. pneumoniae infections.

Efflux pump activity, biofilm formation and antibiotic resistance profile of Klebsiella spp. isolated from clinical samples at Lagos University Teaching Hospital

Objective

Nosocomial and community acquired multidrug resistant Klebsiella infections are wide spread resulting in high morbidity and mortality due to limited number of antibiotics treatment options. This study investigated efflux pump activity, biofilm forming potential and antibiotic susceptibility profile of Klebsiella spp. isolated from clinical samples in a tertiary hospital in Lagos Nigeria. Eighteen clinical Klebsiella spp. isolated from urine, blood and sputum were subjected to antibiotic susceptibility testing using the disc diffusion method. Efflux pump activity was evaluated by the ethidium bromide cartwheel method and biofilm forming ability was determined by the tissue culture plate technique.

Results

All 18 (100%) Klebsiella isolates were resistant to cefuroxime, cefixime, amoxicillin − clavulanate, ampicillin + cloxacillin, cefotaxime, and imipenem. Seventeen (94.4%) were resistant to ofloxacin while sixteen (88.9%) were resistance to nalidixic acid, Gentamicin and levofloxacin. All Klebsiella isolates possessed active efflux pump with the ability to form biofilm. However, their biofilm forming capabilities varied as 4 (22.2%) were strong, 3 (16.7%) were moderate and 11 (61.1%) were weak biofilm formers. Findings in this study reveal multiple factors at play in mediating the high level of antibiotic resistance observed in Klebsiella isolates. Hence a multifaceted approach is advocated in managing the infections caused by the pathogen.

Identifying novel inhibitor of quorum sensing transcriptional regulator (SdiA) of Klebsiella pneumoniae through modelling, docking and molecular dynamics simulation

In this study, attempts have been made to identify novel inhibitor(s) of SdiA (a homolog of LuxR transcription regulator) of Klebseilla pneumoniae using various computational techniques. 4LFU was used as a template to model the structure of SdiA. ProCheck, Verify3D, Ramachandran plot scores and ProSA-Web confirmed the good quality of the model as the root mean square deviation (RMSD) between SdiA model, and 4LFU template was estimated to be 0.21 Å. The secondary structural contents of SdiA model were predicted using PDBsum. The only binding site of SdiA was identified (area = 523.083 Ų and volume = 351.044 ų) using CASTp. Molecular docking at three different levels [high throughput virtual screening, standard-precision (SP) and extra-precision (XP) dockings] with increasingly stringent conditions was performed using Glide on Selleck's express pick library (L3600). A total of 61 ligands were found to bind with high affinities to the active site of SdiA. Further, the effect of solvent on protein-ligand interaction was evaluated by performing molecular mechanics-general born surface area (Prime/MM-GBSA). On the basis of Prime/MM-GBSA score, molecular dynamics simulation (50 ns) was performed on the ligand (WAY-390139-A) showing lowest binding energy to confirm the stability of protein-ligand complex. Docking energy and the corresponding binding affinity of WAY-390139-A towards SdiA were estimated to be -13.005 kcal mol^-1 and 3.46 × 10⁹ M^-1, respectively. Our results confirm that WAY-390139-A binds at the autoinducer binding site of SdiA with high affinity and stability and can be further exploited as potential drug against K. pneumoniae after experimental validation.Communicated by Ramaswamy H. Sarma.

Promising strategies for future treatment of Klebsiella pneumoniae biofilms

Klebsiella pneumoniae is a Gram-negative pathogenic bacterium that has the ability to aggregate as biofilm, representing one of the main agents in hospital infections, showing high rates of resistance to antibiotics. The K. pneumoniae biofilm aggregates are composed mainly of extracellular polysaccharides, eDNA and proteins. Besides, biofilms can attach to medical devices, such as endotracheal tubes and catheters, but are most dangerous on body surfaces. Here, we discuss the recent findings about the resistance mechanisms of K. pneumoniae biofilms, including genes and protein involved in 'classic', multidrug-resistant and hypervirulent strains, and also virulence factors. In addition, we also explore new strategies for possible treatment of these biofilms, and recently discovered molecules which may lead to future treatments.

Antibody-recruiting protein-catalyzed capture agents to combat antibiotic-resistant bacteria

Antibiotic resistant infections are projected to cause over 10 million deaths by 2050, yet the development of new antibiotics has slowed. This points to an urgent need for methodologies for the rapid development of antibiotics against emerging drug resistant pathogens. We report on a generalizable combined computational and synthetic approach, called antibody-recruiting protein-catalyzed capture agents (AR-PCCs), to address this challenge. We applied the combinatorial protein catalyzed capture agent (PCC) technology to identify macrocyclic peptide ligands against highly conserved surface protein epitopes of carbapenem-resistant Klebsiella pneumoniae, an opportunistic Gram-negative pathogen with drug resistant strains. Multi-omic data combined with bioinformatic analyses identified epitopes of the highly expressed MrkA surface protein of K. pneumoniae for targeting in PCC screens. The top-performing ligand exhibited high-affinity (EC₅₀ ∼50 nM) to full-length MrkA, and selectively bound to MrkA-expressing K. pneumoniae, but not to other pathogenic bacterial species. AR-PCCs that bear a hapten moiety promoted antibody recruitment to K. pneumoniae, leading to enhanced phagocytosis and phagocytic killing by macrophages. The rapid development of this highly targeted antibiotic implies that the integrated computational and synthetic toolkit described here can be used for the accelerated production of antibiotics against drug resistant bacteria.

Biofilm formation and antibiotic resistance of Klebsiella pneumoniae isolated from clinical samples in a tertiary care hospital, Klaten, Indonesia

Background

Klebsiella pneumoniae (K. pneumoniae) is a common cause of health-care associated infections (HAIs) and has high levels of antibiotic resistance. These bacteria are well-known for their ability to produce biofilm. The purpose of this study was to identify the antibiotic resistance pattern and biofilm-producing capacity of K. pneumoniae isolated from clinical samples in a tertiary care hospital in Klaten, Indonesia.

Methods

K. pneumoniae was isolated from inpatients in Soeradji Tirtonegoro Hospital Klaten from June 2017 to May 2018. Identification of K. pneumoniae isolate was done by analyzing colony morphology, microscopic examination, and by performing biochemical testing. Testing of antibiotics susceptibility and biofilm-producing capacity used the Kirby-Bauer disk diffusion method and adherence quantitative assays, respectively.

Results

A total of 167 (17.36%) K. pneumoniae isolates were isolated from 962 total clinical bacterial isolates during the study. Most of them were collected from patients aged more than 60 years old and were mainly obtained from respiratory specimens (51.50%). Most of K. pneumoniae isolates were extensively resistant to antibiotics. A more favorable profile was found only towards meropenem, amikacin, and piperacillin-tazobactam, showing 1.20%; 4.79% and 10.53% of resistance, respectively. The overall proportion of multidrug-resistant K. pneumoniae isolates was 54.49%. In addition, 148 (85.63%) isolates were biofilm producers, with 45 (26.95%) isolates as strong, 48 (28.74%) isolates as moderate, and 50 (29.94%) isolates as weak biofilm producers.

Conclusion

Most of the K. pneumoniae isolates demonstrated resistance to a wide range of antibiotics and are biofilm producers.

Biofilm formation by multidrug resistant Enterobacteriaceae strains isolated from solid organ transplant recipients

Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant bacteria (MDR). In this study, the biofilm-forming capability of 209 MDR strains (Escherichia coli n = 106, Klebsiella pneumoniae n = 78, and Enterobacter spp. n = 25) isolated from rectal swabs in the first 48 hours before or after kidney (93 patients), liver (60 patients) or kidney/pancreas transplants (5 patients) were evaluated by using a microplate assay. Thirty-nine strains were isolated before transplant and 170 strains were isolated post-transplant. Overall, 16% of E. coli strains, 73% of K. pneumoniae strains and 4% Enterobacter strains showed moderate or strong biofilm production. Nine strains isolated from infection sites after transplantation were responsible of infections in the first month. Of these, 4 K. pneumoniae, 1 E. coli and 1 Enterobacter spp. strains isolated pre-transplant or post-transplant as colonizers caused infections in the post-transplant period. Our results suggest that in vitro biofilm formation could be an important factor for adhesion to intestine and colonization in MDR K. pneumoniae strains in SOT recipients, but this factor appears to be less important for MDR E. coli and Enterobacter spp.