基于高通量共聚焦激光扫描显微镜方法定量分析副溶血性弧菌生物被膜结构

【目的】副溶血性弧菌是水产品中常见的食源性致病菌,生物被膜的形成对副溶血性弧菌的环境生存和传播至关重要。这项工作的目的是评估临床和环境中分离出的44株副溶血性弧菌菌株形成的生物被膜的结构多样性。【方法】该研究基于共聚焦激光扫描显微镜的高通量方法,使用与高分辨率成像兼容的96孔微量滴定板,结合结构分析软件ISA-2来研究生物被膜形成和结构,分析22株食品与22株临床来源的副溶血性弧菌菌株形成的生物被膜结构参数(生物体积、平均厚度、粗糙系数)。【结果】CLSM图像显示,44株副溶血性弧菌菌株在培养48h后能够形成3D结构,进一步比较分析了临床来源菌株与环境来源菌株形成的生物被膜结构异同,发现临床菌株生物被膜的变异系数比环境菌株生物被膜的变异系数小,且同时携带tdh和trh两种毒力因子的菌株生物被膜变异性最小。凝聚层次聚类分析结果显示,副溶血性弧菌生物被膜可以分为致密且表面光滑(39%)、斑驳且表面粗糙(27%)、疏松且表面坑洼(34%),临床菌株易形成致密且表面光滑和斑驳且表面粗糙的生物被膜,而环境菌株易形成致密且表面光滑和疏松且表面坑洼的生物被膜。【结论】该研究深入了解了副溶血性弧菌生物被膜结构差异性,为今后对临床和环境来源的副溶血性弧菌生物被膜采取不同的防控和清除措施提供了理论支撑。     

Antibacterial potential of Forsythia suspensa polysaccharide against resistant Enterobacter cloacae with SHV‐12 extended‐spectrum β‐lactamase (ESBL)

In this study, a homogenous polysaccharide (FSP), with an average molecular weight of 9.08 × 10⁴ Da, was isolated from Forsythia suspense and its antibacterial potential against Enterobacter cloacae producing SHV‐12 ESBL was investigated. Growth kinetics, in vitro competition and biofilm formation experiments demonstrated that SHV‐12 ESBL contributed to a fitness benefit to E cloacae strain. The antibacterial activity of FSP (2.5, 5.0 and 10.0 μg/mL) was tested against E cloacae bearing SHV‐12 ESBL gene using bacterial sensitivity, agar bioassay and agar well diffusion assays. It was found that the addition of FSP demonstrated potent antibacterial activities against this bacterial as showed by the decrease of bacterial growth and the increase of the inhibition zone diameter. Furthermore, SHV‐12 ESBL gene expression was decreased in E cloacae strain following different FSP treatment in a concentration‐dependent manner. In conclusion, these data showed that FSP exhibited potent good antibacterial activity against E cloacae producing SHV‐12 ESBL via inhibition of SHV‐12 ESBL gene expression, which may promote the development of novel natural antibacterial agents to treat infections caused by this drug‐resistant bacterial pathogen.     

Antibiotic susceptibility and occurrence of ESBL, IBL and MBL in Pseudomonas aeruginosa strains

The aim of this study was to evaluate the drug susceptibility of P. aeruginosa strains and to detect strains producing inducible beta-lactamases (IBL), extended-spectrum beta-lactamases (ESBL), and metallo-beta-lactamases (MBL). During 6 month (October 2005 - March 2006), 66 strains of P. aeruginosa strains were cultured from clinical specimens obtained from patients of two of hospitals in Siedlce and from patients of outpatient clinics. All the strains were identified in the automatic ATB (bio Mérieux). The susceptibility of bacteria to antibiotics was tested by standard disc diffusion method. The majority of strains were susceptible to meropenem (89.4%), piperacillin combined with tazobactam (84.8%), ciprofloxacin (84.8%) and piperacillin (83.3%). Many of our strains were resistant to carbenicillin (69.7%), mezlocillin (45.5%), gentamicin (42.4%) and netylmicin (30.3%). 6 strains (9.1%) were multidrug-resistant (MDR). Inducible beta-lactamases were detected with the use double disc method according to Sanders and Sanders. ESBL-producing strains were detected with double disc test (DDST) according to Jarlier et al. These strains were identified as ESBL-positive on the basis of the DDST were also determined using a double disc (DD) test according to Appleton. Production of metallo-beta-lactamases (MBL) was examined with the use of Etest MBL (AB Biodisk, Sweden) and the double disc test according to Arakava et al. Sixty-five IBL-producing strains (98.5% of all strains) and three strains (4.5%) with MBL activity were detected. Strains producing extended beta-lactamases (ESBL) were not found.     

In Silico Design,Synthesis, and In Vitro Evaluation of Novel Amphipathic Short Linear Peptides Against Clinically Relevant Bacterial Biofilms

Microbial biofilms are organized communities of cells that are associated with a wide spectrum of resistant and chronic infections that lead to the treatment failure. Accordingly, there is an urgent demand to create novel effective therapeutic drugs that can inhibit biofilm formation with new mechanisms of action to surmount the current escalating resistance. In this study, in silico hybrid model was utilized to develop three novel short linear peptides (4, 5, and 6) with potential biofilm inhibiting activities (scores?>?1.0). The peptides were composed of cationic and hydrophobic residues. They were synthesized using solid-phase strategy. Synthesized peptides were purified and characterized by reverse-phase high-performance liquid chromatography and matrix-assisted laser desorption/ionization spectroscopy, respectively. They were evaluated using in vitro assay as potential inhibitors of clinically relevant Gram-positive and Gram-negative biofilms. Peptide (4) with five positive charges at physiological pH (4 cationic moieties and W:R?=?1:4) showed activity against biofilms of Gram-positive strains (Staphylococcus epidermidis and Listeria monocytogenes). On the other hand, peptide (5) with six positive charges (5 cationic moieties and W:R?=?2:2) demonstrated activity against Gram-positive (S. epidermidis) and Gram-negative (Escherichia coli) biofilms. Interestingly, peptide (6), with seven positive charges (6 cationic moieties and W:R?=?2:5) revealed higher and broader spectrum of activity against biofilms of Gram-positive (S. epidermidis, S. aureus, L. monocytogenes) and Gram-negative (E. coli).

     

Extended spectrum beta-lactamase and metallo beta-lactamase production among <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> isolated from different clinical samples in a tertiary care hospital in Kathmandu,Nepal

Background

Extended spectrum beta-lactamase (ESBL) and metallo beta-lactamase (MBL) production in Klebsiella pneumoniae and Escherichia coli are the commonest modes of drug resistance among these commonly isolated bacteria from clinical specimens. So the main purpose of our study was to determine the burden of ESBL and MBL production in E. coli and K. pneumoniae isolated from clinical samples. Further, the antimicrobial susceptibility patterns of E. coli and K. pneumoniae were also determined.

Methods

A cross-sectional study was conducted at Om Hospital and Research Centre, Kathmandu, Nepal by using the E. coli and K. pneumoniae isolated from different clinical samples (urine, pus, body fluids, sputum, blood) from May 2015 to December 2015. Antimicrobial susceptibility testing was performed by Kirby-Bauer disc diffusion technique. Extended spectrum beta-lactamase production was detected by combined disc method using ceftazidime and ceftazidime/clavulanic acid discs and cefotaxime and cefotaxime/clavulanic acid discs. Similarly, metallo beta-lactamase production was detected by combined disc assay using imipenem and imipenem/ethylenediaminetetracetate discs. Bacteria showing resistance to at least three different classes of antibiotics were considered multidrug resistant (MDR).

Results

Of total 1568 different clinical samples processed, 268 (17.1%) samples were culture positive. Among which, E. coli and K. pneumoniae were isolated from 138 (51.5%) and 39 (14.6%) samples respectively. Of the total isolates 61 (34.5%) were ESBL producers and 7 (4%) isolates were found to be MBL producers. High rates of ESBL production (35.9%) was noted among the clinical isolates from outpatients, however no MBL producing strains were isolated from outpatients. Among 138 E. coli and 39 K. pneumoniae, 73 (52.9%) E. coli and 23 (59%) K. pneumoniae were multidrug resistant. The lowest rates of resistance was seen toward imipenem followed by piperacillin/tazobactam, amikacin and cefoperazone/sulbactam.

Conclusions

High rate of ESBL production was found in the E. coli and K. pneumoniae isolated from outpatients suggesting the dissemination of ESBL producing isolates in community. This is very serious issue and can’t be neglected. Regular monitoring of rates of ESBL and MBL production along with multidrug resistance among clinical isolates is very necessary.

     

Prevalence of Community-Occurring Extended Spectrum β-Lactamase-Producing <Emphasis Type="Italic">Enterobacteriaceae</Emphasis> in Brazil

The occurrence of extended-spectrum-β-lactamase (ESBL)-producing strains in the community was investigated in a private laboratory located in Juiz de Fora, Brazil. All enterobacterial isolates analysed were collected from urine of human patients between the years 2000 and 2002. ESBL production was confirmed by double disk screening, combination disk method, and Etest ESBL strip. The isoelectric point of each β-lactamase was determined in the crude extracts from each isolate. Detection of ESBL genes was performed by polymerase chain reaction and the genetic relatedness of the isolates determined by pulsed-field gel electrophoresis (PFGE). Of the 1,481 isolates, 22 (12 Klebsiella pneumoniae, 7 Escherichia coli, 1 Providencia stuartii, 1 Citrobacter freundii, and 1 Serratia marcescens) were identified as ESBL producers. The frequency of ESBL producers in the community was 1.48%. TEM-type enzymes were identified in 95.4% of the isolates, followed by the SHV type. Seven strains produced CTX-M–type enzymes. This study showed that strains producing multiple β-lactamases are also present in community-acquired bacterial isolates. Multiple strains exhibiting identical PFGE genotypes were found in individual patients indicating a common source of acquisition.     

Staphylococcus aureus biofilm susceptibility to small and potent β2,2-amino acid derivatives

Small antimicrobial β^2,2-amino acid derivatives (Mw < 500 Da) are reported to display high antibacterial activity against suspended Gram-positive strains combined with low hemolytic activity. In the present study, the anti-biofilm activity of six β^2,2-amino acid derivatives (A1–A6) against Staphylococcus aureus (ATCC 25923) was investigated. The derivatives displayed IC₅₀ values between 5.4 and 42.8 μM for inhibition of biofilm formation, and concentrations between 22.4 and 38.4 μM had substantial effects on preformed biofilms. The lead derivative A2 showed high killing capacity (log R), and it caused distinct ultrastructural changes in the biofilms as shown by electron and atomic force microscopy. The anti-biofilm properties of A2 was preserved under high salinity conditions. Extended screening showed also high activity of A2 against Escherichia coli (XL1 Blue) biofilms. These advantageous features together with high activity against preformed biofilms make β^2,2-amino acid derivatives a promising class of compounds for further development of anti-biofilm agents.     

In vitro activity of three different antimicrobial agents against ESBL producing Escherichia coli and Klebsiella pneumoniae blood isolates

Extended spectrum beta-lactamases (ESBLs) usually associated with multiple drug resistance, including beta-lactam and non-beta-lactam antibiotics. This resistance can cause Limitation in the choice of drugs appropriate for using in clinical practice, especially in life-threatening infections. In this study we aimed to investigate in vitro activity of meropenem, ciprofloxacine and amikacin against ESBL-producing and non-producing blood isolates of Escherichia coli and Klebsiella pneumoniae strains. Fifty-eight E. coli (21 ESBL-producing, 37 non-ESBL producing) and 99 K. pneumoniae (54 ESBL-producing, 45 non-ESBL producing) strains were included in the study. The presence of ESBL was investigated by double disk synergy test and E-test methods. Antibiotic susceptibility test was done by microdilution method according to NCCLS guideline. In vitro susceptibilities of ESBL producing E. coli and K. pneumoniae strains were found as 100% for meropenem, 33.3% and 25.9% for ciprofloxacine, 94.5% and 83.3% for amikacin. It was observed that; meropenem was equally active agent in both ESBL-producing and non-producing strains, and its activity was not affected by ESBL production. Whereas amikacin activity was minimally affected and ciprofloxacine activity was markedly decreased by ESBL production. In conclusion, meropenem seems to be better choice of antibiotic should be used for ESBL positive life-threatening infections, because of remaining highest activity.     

Multi-drug resistant,biofilm-producing high-risk clonal lineage of Klebsiella in companion and household animals

Antimicrobial resistance is a global emergency which needs one health approach to address. The present study was conducted to detect the prevalence of beta-lactamase and biofilm-producing Klebsiella strains in rectal swabs (n = 624) collected from healthy dogs, cats, sheep and goats reared as companion or household animals in India. The dogs and cats were frequently exposed to third- or fourth-generation cephalosporins for therapy. The sheep and goats were occasionally exposed to antibiotics and had environmental exposure. Phenotypical ESBL (n = 93) and ACBL (n = 88)-producing Klebsiella were isolated significantly more (P < 0·05) from companion animals than household animals. Majority of the Klebsiella possessed bla_CTX-M-15. The sequences bla_CTX-M-15.2, bla_CTX-M-197 and bla_CTX-M-225 are reported first time from the companion animals. All ACBL-producing isolates possessed bla_AmpC. The present study detected 65·8% of Klebsiella strains as biofilm producers possessing the studied biofilm associated genes. The isolates showed phenotypical resistance against chloramphenicol, tetracycline, doxycycline, co-trimoxazole, ampicillin, cefotaxime/clavulanic acid. The present study showed that companion and household animals (dogs, cats, sheep, goats) may act as a carrier of ESBL/biofilm-producing, multi-drug resistant, high-risk clonal lineage of Klebsiella.     

Extended spectrum beta-lactamases in <Emphasis Type="Italic">Escherichia coli</Emphasis> strains isolated from homemade white cheeses: prevalence and antibiotic susceptibility

The present study included 223 E. coli strains isolated from homemade white cheeses and was undertaken to determine the prevalence of extended spectrum β-lactamases (ESBL)-producing strains and antibiotic susceptibility. ESBL production was detected using three methods: the NCCLS disk diffusion test, the double disk synergy test and the NCCLS confirmatory test. By the disk diffusion test, 48% isolates were determined as potential ESBL producers. ESBL production by the double disk test and the phenotypic confirmatory test was found to be 16.1 and 9.9%, respectively. Susceptibility of all isolates against 16 antimicrobials was tested by the disk diffusion method. All strains were imipenem- and cefepime-susceptible. Susceptibility of E. coli to ceftazidime, ceftriaxon, cefotaxime and aztreonam was found to be 93.7, 96.4, 81.2, 90.6%, respectively. The least effective antibiotics were ampicillin with a rate of 68.6% and cefuroxime with a rate of 69.1%.     

副溶血性弧菌-霍乱弧菌混合生物被膜形成过程研究

【目的】研究副溶血性弧菌(Vibrioparahaemolyticus,VP)和霍乱弧菌(Vibriocholera,VC)混合生物被膜的形成过程。【方法】在4、8、12、24、36、48、60、72 h测定单独条件下VP、VC及其混合后生物被膜的形成情况,通过结晶紫染色法、平板菌落计数法、测定胞外多糖、胞外蛋白,通过荧光原位杂交(FISH)观察混合生物被膜形成。【结果】虽然形成的混合生物被膜量介于VC和VP之间,但混合生物被膜在形成过程中,成熟期后生物被膜量的变化较小,对环境的抗性增强。混合生物被膜中拥有更多的活菌,混合生物被膜形成过程中胞外蛋白和胞外多糖的变化体现出其可能在对抵御不适应环境中起重要作用,通过FISH可观察到不同时期生物被膜的变化过程。【结论】VC与VP共同形成生物被膜的过程中,混合生物被膜总量虽然减少,但混合生物被膜中拥有更多的活菌,这可能引起更大的危害。研究混合生物被膜形成过程中被膜的变化,可为有害生物被膜的控制提供基础。     

Antifungal Activity,Antibiofilm and Association Studies with O-Alkylamidoximes against Cryptococcus spp.

This is the first study that describes the antifungal and anti-biofilm potential of O-alkylamidoximes against strains of Cryptococcus neoformans and Cryptococcus gattii. In vitro tests have shown that O-alkylamidoximes are capable of inhibiting fungal growth and biofilm formation of the C. neoformans and C. gattii strains, suggesting, from molecular docking, the potential for interaction with the Hsp90. The associations between O-alkylamidoximes and amphotericin B were beneficial. Therefore, O-alkylamidoximes can be a useful alternative to contribute to the limited arsenal of drugs, since they showed a powerful action against the primary agents of Cryptococcosis.     

Anti-virulence activity of novel (1-heteroaryloxy-2-hydroxypropyl)- phenylpiperazine derivatives against both wild-type and clinical drug-resistant Candida albicans strains

Candida albicans is an important human fungal pathogen. Our previous study disclosed that aryloxy-phenylpiperazine skeleton was a promising molecule to suppress C. albicans virulence by inhibiting hypha formation and biofilm formation. In order to deeply understand the efficacy and mechanism of action of phenylpiperazine compounds, and obtain new derivatives with excellent activity against C. albicans, hence, we synthesized three series of (1-heteroaryloxy-2-hydroxypropyl)-phenylpiperazines and evaluated their inhibitory activity against C. albicans both in vitro and in vivo in this study. Compared with previously reported aryloxy-phenylpiperazines, part of these heteroaryloxy derivatives improved their activities by strongly suppressing hypha formation and biofilm formation in C. albicans SC5314. Especially, (9H-carbazol-4-yl)oxy derivatives 25 , 26 , 27 and 28 exhibited strong activity in reducing C. albicans virulence in both human cell lines in vitro and mouse infection models in vivo. The compound 27 attenuated the virulence of various clinical C. albicans strains, including clinical drug-resistant C. albicans strains. Moreover, additive effects of the compound 27 with antifungal drugs against drug-resistant C. albicans strains were also discussed. Furthermore, the compound 27 significantly improved the composition and richness of the faecal microbiota in mice infected by C. albicans. These findings indicate that these piperazine compounds have great potential to be developed as new therapeutic drugs against C. albicans infection.     

Molecular characterization of the β‐lactamases in Escherichia coli and Klebsiella pneumoniae from a tertiary care hospital in Riyadh,Saudi Arabia

The widespread use of antimicrobials has increased the occurrence of multidrug resistant microbes. The commonest mechanism of antimicrobial resistance in Enterobacteriaceae is production of β‐lactamases such as metallo‐β‐lactamases (MBL) and extended spectrum β‐lactamases (ESBL). Few studies have used a molecular approach to characterize the prevalence of β‐lactamases. Here, the prevalence of different β‐lactamases was characterized by performing three multiplex PCRs targeting genes similar to those described in earlier publications. Antimicrobial susceptibility tests for all isolates were performed using the agar dilution method. β‐lactamase was detected in 72% of the isolates, the detection rate being 64% in 2011 and 75% in 2012. The isolates were highly resistant to carbapenems such as meropenem and imipenem and susceptible to colistin and tigecycline. In this study, 22% of isolates contained both MBL and ESBL. ESBL was detected more frequently in Escherichia coli isolates, whereas carbapenemase was detected more frequently in Klebsiella pneumoniae isolates. These findings suggest the spread of multi‐resistant ESBL and MBL producers in the community. Our results have implications for patient treatment and also indicate the need for increased surveillance and molecular characterization of isolates.     

2-Hydroxy-4-methoxybenzaldehyde from Hemidesmus indicus is antagonistic to Staphylococcus epidermidis biofilm formation

Abstract

Staphylococcus epidermidis (SE) is an opportunistic nosocomial pathogen that accounts for recalcitrant device-related infections worldwide. Owing to the growing interest in plants and their secondary metabolites targeting bacterial adhesion, this study was intended to uncover the anti-biofilm potential of Hemidesmus indicus and its major constituent 2-hydroxy-4-methoxybenzaldehyde (HMB) against SE. The minimum biofilm inhibitory concentration (MBIC) of H. indicus root extract and HMB were found to be 500 and 250?µg ml^?1, respectively. The results of time-dependent biofilm inhibition and mature biofilm disruption assays confirmed that HMB targets initial cell adhesion. Furthermore, interference by HMB in the expression of adhesin genes (icaA, aap and bhp) and biofilm components was associated with an increased susceptibility of SE to oxidative stress and antibiotics. To conclude, this study reports for the first time HMB as a potential drug against SE biofilms.     

Evaluation of a chromogenic agar medium for the detection of extended-spectrum ß-lactamase-producing Enterobacteriaceae

Aim: To compare the performance of a new chromogenic agar medium CHROMagar ESBL (KC‐ESBL) to chromID ESBL (SB‐ESBL) for the detection and presumptive identification of extended‐spectrum β‐lactamase (ESBL)‐producing Enterobacteriaceae directly from clinical specimens. Methods and Results: A total of 256 specimens were screened for ESBL producers. Also, the genotypes of the ESBLs and plasmid‐mediated AmpC β‐lactamases (pAmpCBLs) were characterized by PCR and sequencing. Among the 256 specimens, 17 (6·6%) ESBL producers were isolated on both media. The sensitivity, specificity, positive predictive value and negative predictive value were higher for KC‐ESBL (100, 93·3, 51·5 and 100%, respectively) than for SB‐ESBL (88·2, 92·9, 46·9 and 99·1%, respectively) (P = 0·72). Enterobacteriaceae harbouring pAmpCBL genes as well as chromosomal cephalosporinase‐ and penicillinase‐hyperproducing Enterobacteriaceae and Pseudomonas aeruginosa accounted for the false‐positive results. Conclusion: KC‐ESBL can detect ESBL producers from clinical specimens with good selectivity and rapid presumptive identification by means of colony colour at 24 h. Significance and Impact of the Study: This is the first study that has evaluated the performance of KC‐ESBL that enables the detection and presumptive identification of ESBL producers from clinical specimens.     

Campanula portenschlagiana Roem. et Schult.: Chemical and Antimicrobial Activities

The phytochemical profile and the antimicrobial effects of the volatile oil and the aqueous extract of Campanula portenschlagiana, a wild growing plant endemic to Croatia, were described. In the volatile oil, 53 compounds were identified by GC‐FID and GC/MS analyses. Diterpene alcohols constituted the major compound class with labda‐13(16),14‐dien‐8‐ol as the main compound. The aqueous extract was characterized by the total phenolic content. The antimicrobial potential of the volatile oil and the aqueous extract was evaluated against a diverse range of microorganisms comprising food‐spoilage and food‐borne pathogens. The volatile oil exhibited interesting and promising antimicrobial effects against the tested species, which were generally more pronounced against Gram‐negative bacteria. In addition, the inhibitory effect of this volatile oil was also evaluated against eleven extended‐spectrum β‐lactamase (ESBL)‐producing isolates. The results suggest that the C. portenschlagiana volatile oil might be used as antimicrobial agent against ESBL‐producing isolates and Gram‐negative bacteria.     

Effect of cinnamaldehyde on biofilm formation and sarA expression by methicillin‐resistant Staphylococcus aureus

Aims: To investigate the antibiofilm effect of cinnamaldehyde on methicillin‐resistant Staphylococcus aureus (MRSA) and analyse the effect of subminimum inhibitory concentrations (MICs) of cinnamaldehyde on the expression of the biofilm‐related gene sarA. Methods and Results: The MICs and minimum bactericidal concentrations (MBCs) were determined using a microtitre broth dilution method. Biofilm susceptibility was determined using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) staining and colony forming unit (CFU) counting assays. Antibiofilm effects were studied with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). SarA expression was assessed by real‐time PCR. MICs and MBCs were in the range 0·0625–0·5% (v/v). The killing effects were concentration dependent. At a concentration of 5× MIC, all strains in biofilm were decreased to lower than 20% of the control groups. SEM and CLSM images indicated that a 5× MIC concentration of cinnamaldehyde was able to detach and kill existing biofilms. Apart from strain JB‐06, real‐time PCR showed that the expression of sarA of all other strains was decreased upon exposure to sub‐MICs of cinnamaldehyde. Conclusions: These data showed the strong killing effect of cinnamaldehyde against MRSA within biofilms. Significance and Impact of the Study: This study indicated the potential of cinnamaldehyde as an inhibitory agent for use in MRSA biofilm‐related infections.     

Providencia isolates carrying bla (PER-1) and bla (VIM-2) genes: biofilm-forming capacity and biofilm inhibitory concentrations for carbapenem antibiotics

Multidrug-resistant clinical isolates of Providentia carrying bla _PER-1 and bla _VIM-2 were evaluated for the abilities to form biofilm and high biofilm forming capacity was demonstrated in them. Minimum biofilm inhibitory concentrations (MBICs), minimum biofilm eradication concentrations (MBECs), and minimum inhibitory concentrations (MICs) for imipenem and meropenem were also determined. In all tested strains, the MBICs were higher than the MICs for both drugs. Interestingly, the MBICs and the MBEC₅₀ for meropenem were lower than those for imipenem in the isolates producing high amounts of biofilm, suggesting that meropenem is superior to imipenem in the growth inhibition and eradication of biofilm forming Providentia strains.     

Naringin inhibits the biofilms of metallo-β-lactamases (MβLs) producing Pseudomonas species isolated from camel meat

Food producing animals harbouring bacteria carrying drug resistance genes especially the metallo-beta-lactamase (MBL) pose high risk for the human population. In addition, formation of biofilm by these drug resistant pathogens represents major threat to food safety and public health. In this study, metallo-β-lactamases (MβLs) producing Pseudomonas spp. from camel meat were isolated and assessed for their biofilm formation. Further, in vitro and in silico studies were performed to study the effect of flavone naringin on biofilm formation against isolated Pseudomonas spp. A total of 55% isolates were found to produce metallo-β-lactamase enzyme. Naringin mitigated biofilm formation of Pseudomonas isolates up to 57%. Disturbed biofilm architecture and reduced the colonization of bacteria on glass was observed under scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). The biofilm related traits such as exopolysaccharides (EPS) and alginate production was also reduced remarkably in the presence of naringin. Eradication of preformed biofilms (32–60%) was also observed at the respective 0.50 × MICs. Molecular docking revealed that naringin showed strong affinity towards docked proteins with binding energy ranging from −8.6 to −8.8 kcal mol⁻¹. Presence of metallo-β-lactamase producers indicates that camel meat could be possible reservoir of drug-resistant Pseudomonas species of clinical importance. Naringin was successful in inhibiting biofilm formation as well as eradicating the preformed biofilms and demonstrated strong binding affinity towards biofilm associated protein. Thus, it is envisaged that naringin could be exploited as food preservative especially against the biofilm forming food-borne Pseudomonas species and is a promising prospect for the treatment of biofilm based infections.