Culture Plate Method Research Articles

Susceptibility to Vancomycin of Biofilm Producing Staphylococci Isolated from Tertiary Care Hospital of Nepal

BACKGROUND: Methicillin resistance and biofilm-producing Staphylococci are emerging as multidrug-resistant strains narrowing the efficacy of antimicrobial therapy. Although vancomycin is used as the drug of choice to treat such isolates, different studies worldwide have documented the emergence of strains that are intermediately susceptible or resistant to this antibiotic. OBJECTIVE: The study aimed to determine the minimum inhibitory concentration of vancomycin to methicillin-resistant and biofilm-producing staphylococci isolated from different clinical specimens. METHODS: 375 staphylococci isolated from different clinical specimens over one year were included in the study. Biofilm formation was determined by the Tissue culture plate method (TCP), and ica genes were identified by Polymerase Chain Reaction (PCR). Antibiotic susceptibility and methicillin resistance were done following Clinical and Laboratory Standards Institute (CLSI) guidelines. The minimum inhibitory concentration (MIC) of vancomycin in all isolates was determined by the agar dilution method. RESULTS: Among 375 Staphylococci studied, 43% and 57% represented S. aureus and Coagulase-Negative Staphylococci (CNS), respectively. The rate of Methicillin-Resistant S. aureus (MRSA) and Methicillin-Resistant Coagulase Negative Staphylococci (MRCNS) were 81.4% and 66.8% respectively and determined by the disc diffusion method. The most potential antibiotics were tetracycline and chloramphenicol showing sensitivity to more than 90% isolates. The Minimum Inhibitory Concentration (MIC) value of oxacillin for staphylococci ranged from 0.125-32 μg/ml. Oxacillin agar diffusion method showed 51.6% and 79.9% isolates as MRSA and MRCNS, respectively, revealing a very high percentage of S. aureus and CNS isolates as methicillin-resistant. All isolates had susceptible vancomycin MICs that ranged from 0.125-2 μg/ml. Two S. aureus isolated from Central Venous Catheter (CVC) and catheter specimens were detected with intermediate susceptibility to vancomycin. Similarly, three CNS isolated from blood, CVC, and wound/pus (w/p) were intermediately susceptible to vancomycin. Strong biofilm formation was observed in 22.1% of clinical isolates, and the ica gene was detected among 22.9% of isolates. Only one S. aureus detected as a biofilm producer by the TCP method was found to have intermediate susceptibility to vancomycin. CONCLUSIONS: The increment in vancomycin MIC among methicillin-resistant and biofilm-producing staphylococci is alarming. Strict control measures to prevent methicillin-resistant isolates spread and routine surveillance for vancomycin-resistant isolates must be incorporated in hospitals to prevent antimicrobial treatment failure.

Biofilm Formation and Its Association with Antimicrobial Resistance among Clinical Isolates of Acinetobacter baumanii at a Tertiary Care Hospital in Dhaka City of Bangladesh

Background: Acinetobacter baumanii is responsible for nosocomial infections which are related to the biofilm forming capacity of this pathogen.
 Objective: The purpose of the present study was to detect biofilm formation in clinical isolates of Acinetobacter baumannii and to observe relationship between biofilm formations with its antimicrobial resistance.
 Methodology: This cross-sectional study was conducted in the Department of Microbiology of Dhaka Medical College and Hospital, Dhaka, Bangladesh from July 2015 to June 2016. Acinetobacter baumannii was isolated from different specimens and was identified and were screened for biofilm production by tissue culture plate method. Antimicrobial susceptibility test was done by disc diffusion method.
 Results: A total 300 samples were studied of which 26(8.7%) were Acinetobacter baumannii. From 26 isolated Acinetobacter baumannii, 16(61.5%) were biofilm producers. Biofilm producing Acinetobacter baumannii were 100% resistant to ceftriaxone, ceftazidime, amoxiclav, amikacin and ciprofloxacin. Resistance to imipenem, meropenem, cephotaxime, cefepime and gentamicin were also higher among biofilm producing Acinetobacter baumannii isolates than non-biofilm producers.
 Conclusions: In conclusion the ability of Acinetobacter baumannii forms biofilm and biofilm production has strong association with antimicrobial resistance.
 Bangladesh Journal of Infectious Diseases December 2021;8(2):82-86

Antimicrobial and Environmental activity of biogenic CS-GO nanoparticles on Uropathogens

Bioproduction options for nanoparticles are becoming a highly significant subject, with environmental and economic benefits over physical and chemical processes. The purpose of the current study is to detect the antimicrobial activity of chitosan-Graphene oxide nanoparticles that include The Minimum Inhibitory Concentration (MIC) is a method of determining antibacterial activity, Antibiofilm Activity by Tissue culture plate method, Antioxidant activity, and finally the hemolysis activity of mixing nanoparticles CS-GO that synthesis biologically. the result of Antibacterial activity showed the ID50 for inhibition is at a concentration (1 mg/ml), while the Antibiofilm activity result shows the high concentration of CS-GO nanoparticles (16 mg/ml) showed the higher activity in inhibition of biofilm formation while the less concentration (0.6mg/ml) appeared very low inhibition activity on biofilm formation. The antioxidant activity of nanoparticles showed the high scavenging ability at a concentration (600 mg/ml) as (54.06%) while the less concentration (100mg/ml) appeared scavenger ability as (29.42%) also the hemolysis activity on CS-GO nanoparticles on blood showed different ability at different concentration, the preferred concentration (1mg/ml) show no hemolysis on blood.

Ajwa-Dates (Phoenix dactylifera)-Mediated Synthesis of Silver Nanoparticles and Their Anti-Bacterial, Anti-Biofilm, and Cytotoxic Potential

Green nanotechnology is the evolution of cost-effective and environmentally friendly processes for the production of metal-based nanoparticles due to medicinal importance and economic value. The aim of the present study was to biosynthesize and characterize silver nanoparticles (AgNPs) using the seed extract of Ajwa dates (Aw). The anti-bacteriostatic activity of biosynthesized Aw–AgNPs against Gram-positive and Gram-negative bacterial strains was evaluated. The anti-biofilm activity was examined by the tissue culture plate method. Lastly, the anti-cancer potential of Aw–AgNPs was investigated against the human breast cancer cell line HCC712. UV–visible absorption spectra exhibited the plasmon resonance peak at 430 nm, with the solution undergoing rapid color changes that verified the existence of biosynthesized silver nanoparticles in the solution. TEM and SEM images illustrated that the Aw–AgNPs were spherical and between 15 and 80 nm in diameter. The reduction and stabilization of Aw–AgNPs was due to the functional groups present in the biomolecules of the Ajwa seeds, as identified by FTIR. The Aw–AgNPs exhibited significant anti-bacterial activity against all the tested bacterial strains. Moreover, the Aw–AgNPs efficiently hampered the biofilm formation of the bacterial strains and exhibited cytotoxicity at various concentrations. Overall, these findings suggest that biosynthesized Aw–AgNPs may be used as a potential therapeutic formulation against bacterial infections and breast cancer.

High level of persister frequency in clinical staphylococcal isolates

BackgroundStaphylococcus aureus is a notorious human pathogen that causes often lethal systemic conditions that are mostly medical device associated biofilm infections. Similarly, coagulase negative staphylococci are emerging as leading pathogen for nosocomial infections owing to their ability to form biofilm on implanted medical equipment. Chronic in nature, these infections are difficult to treat. Such recalcitrance of these infections is caused mainly due to the presence of persister cells, which exhibit transient yet extreme tolerance to antibiotics. Despite tremendous clinical significance, there is lack of studies on persister cells formation among clinical bacterial isolates. Considering the importance of factors influencing persister formation, in this study, we evaluate the association of antibiotic tolerance with biofilm production, antibiotic stress, growth phase, specimen type, and dependency on staphylococcal species. Biofilm formation was detected among 375 clinical staphylococcal isolates by quantitative tissue culture plate method (TCP) and icaAD genes by genotypic method. The antibiotic susceptibility was determined by Kirby Bauer disc diffusion method while minimum inhibitory concentration values were obtained by agar dilution method. Persister cells were measured in the susceptible staphylococcal isolates in the presence of clinically relevant antibiotics.ResultsIn the study, 161 (43%) S. aureus and 214 (57%) coagulase negative staphylococci (CNS) were isolated from different clinical samples. TCP method detected biofilm production in 84 (52.2%) S. aureus and 90 (42.1%) CNS isolates. The genotypic method detected icaAD genes in 86 (22.9%) isolates. Majority (> 90%) of both the biofilm producers and non-producers were sensitive to chloramphenicol and tetracycline but were resistant to penicillin. Interestingly, all isolates were sensitive to vancomycin irrespective of biofilm production. While high persister frequency was observed among all staphylococci isolates in the stationary growth phase, the persister frequency in exponential growth phase was statistically high among isolates possessing icaAD genes compared to icaAD negative isolates.ConclusionThe research findings provide strong evidence that the clinical staphylococcal isolates exhibit extreme antibiotic tolerance suggesting their causal link with treatment failures. Understanding the factors influencing the formation and maintenance of persister cells are of utmost important aspect to design therapeutics and control recalcitrant bacterial infections.

The development of platinum-rhodium alloy coatings on SS304 using a pulse/direct electrodeposition technique and their application to antibacterial activity

The current research focused on the development of Platinum–Rhodium alloy coating (Pt– Rh) on SS304 and its applications in antibacterial studies. Electrodeposition is considered to be one of the most suitable methods because it enhances the therapeutic effects of noble metals (Pt–Rh alloy). The electrodeposited coating is an economical and time-saving alternative to existing coating methods. The newly developed Pt–Rh coating was investigated using a scanning electron microscope (SEM) and an atomic force microscope (AFM). Using the agar Petri plate and broth culture method, the antibacterial effect of the platinum-rhodium alloy was investigated against Gram-negative Escherichia coli and Gram-positive bacteria such as Staphylococcus saprophytes, Bacillus Subtilis, and Enterococcus faecalis. The Pt–Rh alloy coated samples obtained by Direct current (DC) and Pulse coating (PC 50% and PC 75%) were examined for antibacterial study. The PC 75% Pt–Rh alloy coating exhibits significant antibacterial activity, demonstrating a maximum zone of inhibition while leaving the rest of the coated samples by DC and PC 50% duty cycles. The study also found that when the concentration of Pt–Rh solution rises from 5 μL to 15 μL, so does the antibacterial activity. The findings of the study showed that electrodeposited platinum-rhodium alloy metal ions may be handy bacteriostatic in the coming years.

Biofilm Production and its Association with Multi Drug Resistance in Pseudomonas aeruginosa among ICU Patients with Special Reference to ESBL, AmpC and MBL production

Multidrug resistant Pseudomonas aeruginosa is an alarming and emerging public health problem globally across the developing countries. Pseudomonas aeruginosa is still a major cause for nosocomial infection and approx 10-20% of these patients are admitted to the ICU’s. Bacterial isolates those are biofilm producers are more drug resistant than biofilm Non-producers. The aim of the present study was to evaluate the production of biofilm and β-lactamases (ESBL, MBL, AmpC) in multi drug resistant Pseudomonas aeruginosa isolated from ICU patients. The present cross-sectional prospective study was carried out in the Department of Microbiology, Santosh Medical College & Hospital, Ghaziabad, Uttar-Pradesh, India. A total of 115 isolates of P. aeruginosa were isolated from 502 clinical samples. After confirmation of MDR status of P. aeruginosa further processing for biofilm and beta lactamases was performed accordingly. Biofilm production was done by test tube method and tissue culture plate method along with phenotypic profiling of ESBL, MBL and AmpC was performed by disc potentiation test; IMP-EDTA combined disc test and Cefoxitin Cloxacillin Double Disc synergy test (CC-DDST) respectively. Out of 502 total human clinical samples 115 isolates were Pseudomonas aeruginosa giving the prevalence rate of 23%. Among 115 isolates of P. aeruginosa 60 (52%) were MDR phenotypes, Out of 60 MDR isolates 23 (38.3%) were ESBL producers, 22 (36.6%) were MBL producers, and 3(5%) were AmpC producers. Out of total 115 isolates 68(59%) isolates were biofilm producers and 47 (40.8%) were biofilm non-producers. Strict antibiotic policies with early detection of beta lactamases and detection of biofilm production should be performed regularly for all clinical isolates of Pseudomonas aeruginosa so as to guide antibiotic selection along with better management of severe infection in ICU patients.

Exploring the diversity of the fungal community in Chinese traditional Baijiu daqu starters made at low-, medium- and high-temperatures

Daqu is a traditional Chinese baijiu starter. To investigate the composition of the microbial community of daqu starters, high-throughput sequencing (HTS) combined with culture-dependent method was used to analyze the fungal diversity of thirty starters made at three temperatures (low-, medium- and high-temperature). In the study, we isolated 420 isolates of fungal strains through the plate culture method. Saccharomyces cerevisiae, Wickerhamomyces anomalus and Saccharomycopsis fibuligera were the most common yeasts encountered in these daqu starters, accounting for 79% of the relative abundance. HTS showed that the dominant genera in low-temperature daqu were distinct from those of medium- and high-temperature. The genera, Thermomyces and Thermoascus, exhibited a higher relative abundance and were considered to be the dominant flora in high-(75%) and medium-(47%) temperature starters, respectively. These two genera were thermotolerant fungi. Saccharomycetaceae was the predominant microflora in low-temperature daqu with a relative abundance of 68%. The present study suggests that the effect of the daqu processing temperature on the fungal community was important and that a knowledge of microbial composition should help to screen fermentation strains thus improving the quality of baijiu liquor.

Development of a device for cultivation and isolation of microbes using a specialized cellulose film

A device was developed for the cultivation and isolation of microbes using a specialized cellulose film (SCF). This method can solve problems associated with the agar plate method. It can also be used for other culture-related operations, which is not possible with the traditional agar plate culture method.

Screening Some Extracellular Enzymes of Wild Mushrooms from Pt. Ravishankar Shukla University Campus

Wild mushrooms are well known to produce wide range of bioactive metabolites and different types of enzymes. In this study 5 wild mushroom samples were collected which belongs to different groups. Samples were isolated and observed the culture characteristics, during the growth of mycelia many biochemical changes are known to occur, as a result of which enzymes are secreted extracellularly to degrade the insoluble materials into the substrates. Primary screening of extracellular amylase and cellulose were carried out by plate culture method in the GYP media with soluble starch to test the amylase activity and for cellulase, CMC (Carboxymethyl cellulose) plate assay was used. All the mushroom cultures differ in context of extracellular enzymatic activity. The activity of amylase enzyme was substantially higher in all the mushroom cultures. In the screening of cellulase enzyme two cultures were observed as positive. Present study suggests the capacity of these wild mushrooms in the production of biotechnologically useful enzymes with great industrial importance.

Isolation and Identification of Biofilm-Producing, Drug-Resistant Coagulase Negative Staphylococci from a Hospital Environment in Northern Philippines

Healthcare-associated infections (HCAIs) are considered adverse outcomes of confinement in a healthcare facility. Biofilm-producing, drug-resistant bacteria have further aggravated the problem with HCAIs. This study determined the prevalence, antibiotic susceptibility, and biofilm phenotype of coagulase-negative staphylococci (CoNS) isolated from a hospital environment in Northern Philippines. The identification of CoNS species and the determination of antibiotic susceptibility were done using an automated assay. Biofilm production was detected using tissue culture plate (TCP) and Congo red agar (CRA) methods. Out of 220 surfaces and 26 air samples collected, 103 (41.9%) CoNS strains were isolated, predominated by S. epidermidis with 30.1% prevalence. The medical ward was found to have the highest prevalence of CoNS at 64%. The CoNS isolates exhibited a variable resistance profile; the highest was found against penicillin (97.1%) and oxacillin (54.3%). Isolates manifesting resistance to linezolid and vancomycin were also detected. From the 103 CoNS isolates, 52 (50.5%) biofilm producers were detected using the TCP method, and 39 (37.9%) were detected by the CRA method. Statistically significant difference was found between the biofilm biomass and the slime-producing pattern. This study revealed the prevalence of biofilm-producing, drug-resistant strains of CoNS in a Level 3 hospital in Northern Philippines. This warrants further enhancement of infection prevention and control programs to avert the emergence of more biofilm-producing, drug-resistant bacterial strains that could pose formidable threats to public health.

Biofilm Formation and Antibiotic Resistance of S. aureus Strains isolated from Chronic Traumatic Wounds

Staphylococcal biofilms are the prominent cause of chronic wound infection and antibiotic resistance. It acts as a reservoir for bacteria, making wound healing difficult. Biofilm infections increase the hospital stays and cost to the patients. The current study explores the phenotypic and genotypic detection of S. aureus biofilm from chronic traumatic wounds and their association with antibiotic resistance. A prospective observational study was conducted from April 2020 to March 2021. S. aureus isolates were identified by the MALDI-TOF. Antibiotic susceptibility was determined by VITEK 2. Biofilm production detected by tissue culture plate method and associated ica genes were diagnosed through multiplex PCR. Overall, 67 isolates were investigated. The frequency of biofilm production in S. aureus was 73.1%, and most of the isolates were moderate biofilm producers (38.8%). The presence of intracellular adhesion (ica) operon among these isolates was 85.7% and also significantly associated with the strength of biofilm mass formation. Ica A was the predominant biofilm-producing gene (42.9%). Biofilm producing Methicillin-resistant S. aureus were as high as 75%, and multidrug resistant strains were significantly associated with biofilm formation. But frequency of ica genes were noted more in Methicillin sensitive S. aureus (65.2%). High frequency of biofilm in S. aureus of isolates was responsible for the development of chronic non-healing traumatic wounds. Biofilm-producing isolates showed greater multidrug-resistance. Phenotypically MRSA expressed more biofilm, but ica operon was documented in MSSA. It emphasized the further need for ica independent pathway exploration for MRSA biofilm synthesis.

An evaluation of three different biofilm detection methods in orthopedic implant associated infections and its implication in healthcare system

: Biofilms are defined as microbially derived sessile communities characterized by the cells that are irreversibly attached to a substratum. These organisms have been associated with implant associated infectionsThe present study is therefore undertaken 1. To compare the three screening methods used for detection of biofilm formation (Tissue culture plate method, Tube method and Congo red agar method) and 2. To correlate the antibiotic resistance pattern of biofilm producers and non biofilm producers. : A prospective study was carried out in the department of microbiology, on all orthopedic implant associated infections from September 2015 to July 2016 on aspirated pus samples. A total of 120 non repetitive clinical isolates were taken and subjected to biofilm detection. All the bacterial isolates were identified by standard biochemical tests. Antibiotic susceptibility test of bacterial isolates was performed by Kirby Bauer disk diffusion method according to Clinical Laboratory Standard Institute (CLSI) guidelines on Muller Hinton Agar (MHA). A reference strain of Staphylococcus epidermidis ATCC 35984(positive biofilm producer) and Staphylococcus epidermidis ATCC 12228(non biofilm producer) were used as controls. Tissue culture plate method was considered as gold standard as it detected 25% biofilm producers which included 12% weak biofilm producers which was missed by congo red agar (CRA) and tube method (TM). Also, this correlated to methicillin resistant staphylococcus aureus (MRSA), ESBL, amp-c and MDR pattern of antibiogram. : TCP is considered as most reliable screening method for biofilm detection and should be routinely employed to prevent treatment failures as these organisms are intrinsically resistant to many antimicrobials leading to implant associated infections.

New update on molecular diversity of clinical Staphylococcus aureus isolates in Iran: antimicrobial resistance, adhesion and virulence factors, biofilm formation and SCCmec typing.

Staphylococcus aureus is often considered as a potential pathogen and resistant to a wide range of antibiotics. The pathogenicity of this bacterium is due to the presence of multiple virulence factors and the ability to form biofilm. SCCmec types I, II and III are mainly attributed to HA-MRSA, while SCCmec types IV and V have usually been reported in CA-MRSA infections. In this study, we performed a cross-sectional study to determine the antimicrobial resistance, adhesion and virulence factors, biofilm formation and SCCmec typing of clinical S. aureus isolates in Iran. S. aureus isolates were identified using microbiological standard methods and antibiotic susceptibility tests were performed as described by the Clinical and Laboratory Standards Institute (CLSI) guidelines. Inducible resistance phenotype and biofilm formation were determined using D-test and tissue culture plate methods, respectively. Multiplex-PCRs were performed to detect adhesion and virulence factors, antibiotic resistance genes, biofilm formation and SCCmec typing by specific primers. Among 143 clinical samples, 67.8% were identified as MRSA. All isolates were susceptible to vancomycin. The prevalence of cMLSB, iMLSB and MS phenotypes were 61.1%, 22.2% and 14.8%, respectively. The TCP method revealed that 71.3% of isolates were able to form biofilm. The predominant virulence and inducible resistance genes in both MRSA and MSSA isolates were related to sea and ermC respectively. SCCmec type III was the predominant type. Data show the high prevalence rates of virulence elements among S. aureus isolates, especially MRSA strains. This result might be attributed to antibiotic pressure, facilitating clonal selection.

ANALYSIS OF THE ANTIBIOGRAM PROFILES OF BIOFILM FORMING STAPHYLOCOCCUS AUREUS AND ESCHERICHIA COLI

Background and Objectives: Bacteria that attach to the surfaces and produce polymeric matrix resulting in the biofilms formation are involved in a wider range of human infections. Biofilms forming Staphylococcus aureus and Escherichia coli are considered to be highly antibiotics resistant. This study aimed to analysis the antibiogram profile of biofilm forming S. aureus and E. coli in Mukalla city, Hadhramaut,Yemen. Methods: Sixty clinical isolates of S. aureus and E. coli were isolated from different clinical samples, and identified by standard bacteriological methods, then subjected to biofilm formation detection by tissue culture plate (TCP) method. The antibiotics susceptibility test was performed by disc diffusion (Kirby-Bauer) method. Chi-square test was used to analyze the data and p value< 0.05 was taken as significant. Results: Among the total isolates S. aureus and E. coli, TCP method detected 55% of isolates as strong, 25% as moderate and 25% as weak/non-biofilm producers. Biofilm forming of S. aureus developed significantly higher degrees of antibiotic resistance of amoxicillin/clavulanic acid100%, ceftazidime 95.8%, cefotaxime62.5%, cefadroxil 45.8%, ciprofloxacin 41.7% and ceftriaxone 25% with significant statistics correlation the resistance of amoxicillin/clavulanic acid and ceftazidime and bacterial biofilm production (p-value< 0.05). The rates of antibiotics resistance biofilm E. coli were 100%, 91.7%, 75%, 70.8%, 66.7%, 62.5% and 33.3%for amoxicillin/clavulanic acid, cefadroxil, cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin and co-trimoxazole respectively with statistically significant correlation of cefadroxil resistance (p-value < 0.05). Conclusion: TCP method showed that S. aureus and E. coli isolates have high degree of biofilm forming ability. A high antibiotics resistance found in biofilm producers isolates than non-biofilm producers. Peer Review History: Received: 23 October 2021; Revised: 1 December; Accepted: 17 December, Available online: 15 January 2022 Academic Editor: Dr. Nuray Arı, Ankara University, Turkiye, ari@ankara.edu.tr UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file: Reviewer's Comments: Average Peer review marks at initial stage: 5.0/10 Average Peer review marks at publication stage: 7.0/10 Reviewers: Dr. Wadhah Hassan Ali Edrees, Hajja University, Yemen, edress2020@gmail.com Dr. Tamer Elhabibi, Suez Canal University, Egypt, tamer_hassan@pharm.suez.edu.eg Dr. Rawaa Souhil Al-Kayali, Aleppo University, Syria, rawah67@hotmail.com Rola Jadallah, Arab American University, Palestine, rola@aauj.edu Similar Articles: PREVALENCE OF STAPHYLOCOCCUS AUREUS IN DENTAL INFECTIONS AND THE OCCURRENCE OF MRSA IN ISOLATES PREVALENCE OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) AND ANTIMICROBIAL SUSCEPTIBILITY PATTERNS AT A PRIVATE HOSPITAL IN SANA'A, YEMEN

Distribution of IcaA and IcaB Genes in Biofilm-Producing Methicillin-Resistance Staphylococcus aureus

Background: Biofilm-producing methicillin-resistance Staphylococcus aureus (MRSA) strains may reduce the penetration rate of antibiotics which leads to treatment failure; therefore, the aim of our study was to assess the presence of icaA and icaB biofilm-producing genes in clinically isolated MRSA strains. Materials and Methods: All pus samples received in the microbiology laboratory were processed as per the standard microbiological procedure for the isolation of S. aureus. Detection of MRSA is done by the cefoxitin disc diffusion method. Phenotypic detection of biofilm in all MRSA strains was accessed by tissue culture plate (TCP) method and polymerase chain reaction as genotypic method was used for detection of icaA and icaB genes. Results: A total of 222 S. aureus were isolated from pus specimens. Out of these, 127 isolates were MRSA (57%). TCP method demonstrated that 68% of MRSA were biofilm producers, on the other hand, 52 (41%) strains showed the presence of icaA gene, and 39 (31%) strains showed the presence of icaB genes in 127 MRSA strains. Conclusion: The detection of biofilm in S. aureus should be considered as essential for better management of diseases caused by biofilm-producing S. aureus strains.

Phenotypic Detection of Biofilm Formation in Clinical Isolates of Methicillin-Resistant Staphylococcus aureus

Background: Staphylococcus aureus is one of the common pathogens which causes mild-to-severe diseases. Moreover, its ability to produce biofilm along with drug resistance makes it more notorious and difficult to treat; therefore, early biofilm detection can help in better management of diseases caused by methicillin-resistant S. aureus (MRSA). Materials and Methods: All clinically isolated S. aureus were screened for their antibiotic susceptibility pattern followed by MRSA status by cefoxitin disk-diffusion method. Evaluation of biofilm-producing nature of biofilm was accessed by tissue culture plate (TCP), tube adhesion (TA), and Congo red agar (CRA) methods. Results: Of all S. aureus isolates, 57% had MRSA status. TCP method showed that 68% of MRSA were biofilm producers. TA method showed 55% and CRA method showed 46% biofilm production. Conclusion: Early detection of MRSA and biofilm could be very beneficial to control S. aureus infection. Of all three biofilm detection methods, TCP method was effective in detecting biofilm, followed by TA and CRA methods.

Importance of detection of Strongyloides stercoralis DNA in fecal samples from patients with type 2 diabetes mellitus

ObjectiveThe association between diabetes and Strongyloides infection remains controversial. This study aimed to detect Strongyloides stercoralis DNA in the feces of patients with Diabetes Mellitus type 2 (DM2). MethodsFecal samples were analyzed via the Lutz, Rugai, and agar plate culture methods. PCR amplification was performed using two targets (PCR-genus and PCR-species) located on the S. stercoralis 18S ribosomal. ResultsThe positivity for S. stercoralis using parasitological methods was 1.1%. PCR-genus (14.13%) demonstrated a higher positivity than PCR-species (9.78%). ConclusionThe results confirm the greater positivity of the molecular diagnosis in relation to parasitological methods, reinforcing its use as an additional tool for the diagnosis of S. stercoralis infection in patients with DM2 living in endemic areas for this helminthiasis.

两种镉积累型小麦根际微生物群落结构及功能多样性

PDF HTML阅读 XML下载 导出引用 引用提醒 两种镉积累型小麦根际微生物群落结构及功能多样性 DOI: 10.5846/stxb202104170997 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 安徽省自然科学基金项目（2008085MD120）；北京市农林科学院创新能力建设专项（KJCX20210439） Rhizosphere microbial community structure and functional diversity in two Cd-accumulating wheat cultivars Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探究不同积累型小麦品种对根际微生物群落结构及功能多样性的影响，以镉低积累型小麦济麦22和镉高积累型小麦冀5265为研究材料，采用分离培养法和Biolog-Eco微平板法分析根际细菌数量、可培养优势群落结构以及微生物群落功能多样性。结果表明：污染土壤济麦22根际总细菌数量和抗Cd细菌数量均显著高于冀5265，而非污染土壤中两品种间无差异。污染土济麦22根际发现较多产脲酶和高镉抗性菌株（200 mg/L）。污染土济麦22根际优势菌多为Arthrobacter sp.和Bacillus sp.，冀5265根际优势菌主要为Streptomyces sp.；非污染土济麦22与冀5265根际优势菌群相似，均以Bacillus sp.为主。Biolog试验结果表明，两个小麦品种根际微生物群落对碳源的利用能力存在差异，济麦22根际微生物AWCD值、Mc Intosh指数、Shannon-Wiener指数、Simpson指数在污染土和无污染土中均显著高于冀5265。因此，污染土壤中不同积累型小麦品种根际微生物群落结构及功能多样性均存在差异，该研究结果对于揭示高低积累型小麦根际微生物机制提供了重要参考依据。 Abstract:In order to investigate the effects of the different accumulating wheat cultivars on rhizosphere microorganism community structure and functional diversity, low Cd-accumulating wheat Jimai 22 (JM22) and high Cd-accumulating wheat Ji 5265 (JI5265) were planted in pots filled with contaminated soil and non-contaminated soil and collected at the tillering stage of wheat. In total, four experimental treatments were set up, containing JM22 grown in contaminated soil (CJM), JI5265 grown in contaminated soil (CJI), JM22 grown in non-contaminated soil (NJM) and JI5265 grown in non-contaminated soil (NJI). The number of rhizosphere bacteria, community structure of culturable dominant bacteria and microbial community functional diversity were analyzed by traditional dilution plate culture method and Biolog-Eco microplate method. The results from the standard spread-plate method showed that the population of total bacteria and Cd-resistant bacteria in rhizosphere soil of JM22 were significantly higher than those of JI5265 in contaminated soil, but there was no significant difference in the population of total bacteria and Cd-resistant bacteria of rhizosphere soil between the two different accumulating wheat cultivars in non-contaminated soil. Studies on the biological characteristics of the isolated strains showed that more urease producing bacterial strains and Cd-resistant bacterial strains (200 mg/L) in rhizosphere soil of JM22 grown in contaminated soil were isolated than those of JI5265 grown in contaminated soil. Based on 16S rRNA gene sequences analysis, bacterial community composition was different in rhizosphere soil between cultivar JM22 and cultivar JI5265 in contaminated soil. Most of the dominant rhizosphere bacteria in JM22 were identified as Arthrobacter sp. and Bacillus sp., while Streptomyces sp. predominated in rhizosphere soil of wheat JI5265 in contaminated soil. The dominant rhizosphere bacteria in JM22 and JI5265 grown in non-contaminated soil were similar, and they were mainly Bacillus sp. The Biolog-Eco plate experiment results showed that there were differences in the utilization of carbon sources between the two wheat cultivars, and the average well color development (AWCD) values, Mc Intosh index, Shannon-Wiener index and Simpson index of rhizosphere microbes of wheat cultivar JM22 were significantly higher than those of cultivar JI5265 in both contaminated soil and non-contaminated soil after 120 h of incubation. Taken together, the community structure and functional diversity of rhizosphere microorganisms in the two Cd-accumulating wheat cultivars grown in contaminated soil were different. The results provide an important reference for understanding the rhizosphere microbial mechanism in high and low accumulating wheats. 参考文献 相似文献 引证文献

Antibiotic Resistance, Biofilm Formation and Sub-Inhibitory Hydrogen Peroxide Stimulation in Uropathogenic Escherichia coli.

Uropathogenic Escherichia coli (UPEC) is the most prevalent cause of urinary tract infections (UTIs). Biofilm formation and antibiotic resistance could be high among the causative agent. The purpose of this study was to determine antibiotic resistance, biofilm production, and biofilm-associated genes, bcsA and csgD, and sub-inhibitory hydrogen peroxide (H2O2) stimulation in UPEC for biofilm formation. A total of 71 UPEC were collected from a tertiary care hospital in Kathmandu and subjected to identify antibiotic susceptibility using Kirby-Bauer disk diffusion. The biofilm formation was assessed using microtiter culture plate method while pellicle formation was tested by a tube method. In representative 15 isolates based on biofilm-forming ability, bcsA and csgD were screened by conventional polymerase chain reaction, and treated with sub-lethal H2O2. The UPEC were found the most susceptible to meropenem (90.2%), and the least to ampicillin (11.3%) in vitro and 90.1% of them were multi-drug resistant (MDR). Most UPEC harbored biofilm-producing ability (97.2%), and could form pellicle at 37°C. Among representative 15 isolates, csgD was detected only among 10 isolates (66.67%) while bcsA gene was present in 13 isolates (86.67%). This study revealed that level of biofilm production elevated after sub-lethal H2O2 treatment (P = .041). These findings suggested that the pathogens are emerging as MDR. The biofilm production is high and the majority of selected strains contained bcsA and csgD genes. Pellicle formation test was suggestive to be an alternative qualitative method to screen biofilm production in UPEC. The sub-inhibitory concentration of H2O2 may contribute in increasing biofilm formation in UPEC.