Molecular Detection of Plasmid-Mediated Quinolone Resistance Genes (qnrA and aac(6?)-Ib-cr) in Drug Resistant Escherichia coli, Sudan

Background: The quinolone group, a synthetic antimicrobial, is widely used worldwide to treat many diseases, including those caused by Gram-negative bacteria. Escherichia coli and others are among the bacteria that produce quinolone resistance genes (qnr) such as qnrA and aac(6?)-Ib-cr. Objective: The present study aimed to the isolate Escherichia coli from patients attending some Hospitals in Wad Medani city, identification of drug resistance patterns and detection of the frequency of quinolones resistance genes; qnrA and aac(6?)-Ib-cr among isolated strains. Methods: A cross-sectional descriptive, hospital-based study included 119 Escherichia coli strains was conducted. A designed questionnaire used for demographic data collection and the attitude toward antimicrobials usage. Clinical specimens were processed for aerobic bacterial isolation and identification. Antimicrobial sensitivity performed by Kirby Bauer disc diffusion technique according to the CLSI guidelines. Presence of qnrA and aac(6?)-Ib-cr genes was assessed by multiplex PCR. Results: Most strains of Escherichia coli originated from urine 53.8% (64/119) and wounds 42.9% (51/119) specimens. Meropenem had the best effect against tested strains with susceptibility of 85% (101/119). Multiplex PCR assay, using specific primers, demonstrated that 41.2% (49/119) and 37.8% (45/119) of isolated Escherichia coli possessed qnrA and aac(6?)-Ib-cr genes respectively. Conclusion: The high rate of qnrA and aac (6)-Ib-cr genes among Escherichia coli necessitate the usage of molecular tools in detecting the genetic determinants of drug resistance microorganisms in countries such as Sudan.

Multiple Resistance in Clinical Isolates of Escherichia coli and Plasmid-mediated Quinolone Resistance Genes

Quinolone antibiotics have been commonly used to treat cases of multiple antibiotic resistance. Unfortunately, quinolone antibiotics have so much been resisted by infectious bacterial agents. This study aimed to evaluate the susceptibility of some clinical isolates of E. coli to some commonly used quinolone antibiotics and the determination of the plasmid-encoded quinolone resistance genes. Our results showed the plasmid quinolone-resistance genes in the following prevalence: qnr genes: qnr S (71.4 %); qnr B (15.4 %); qnr S and B (12.1 %); aac (6) lb-cr (4 %); Efflux genes: oqxA (7.7 %); oqxB (25.3 %); qepA (12.1 %); oqxA and oqxB (5.5 %). We conclude that there is a high frequency of Plasmid-mediated quinolone resistance genes in Escherichia coli isolates from clinical samples in South-Eastern Nigeria. These could be responsible for the high incidence of quinolone resistance reported in Enugu. There is a need for whole-genome sequencing to map out all resistance genes.

Distribution characteristics of integrons and plasmid-mediated quinolone resistance genes in Klebsiella aerogenes clinical isolates / 中华微生物学和免疫学杂志

Objective:To investigate the distribution of integrons and plasmid-mediated quinolone resistance (PMQR) genes in clinical isolates of Klebsiella aerogenes and to analyze the relationship between integrons and bacterial resistance to antimicrobial agents. Methods:Ninety-one Klebsiella aerogenes strains isolated from clinical samples in the Fengxian District Central Hospital from November 2015 to March 2021 were used in this study. Class 1 and class 2 integron-integrase genes ( intI1 and intI2) and PMQR genes were screened by PCR. The types of promoters and gene cassette arrays of variable regions were determined by sequencing. Besides, the relationship between integrons and antimicrobial resistance was analyzed. Results:The resistance rate of the 91 Klebsiella aerogenes isolates to aztreonam was more than 40.00% and the resistance rates to other commonly used antimicrobial agents were less than 35.00%. Among the 91 isolates, 30 carried the intI1 gene, while none of them carried the intI2 gene. Seven class 1 integron gene cassette arrays of variable regions were detected and the gene cassette array of aac(6′)-11 C- ΔereA2- IS1247- aac3- arr- ΔereA2 was detected in Klebsiella aerogenes. PcH1 with weak activity was the predominant variable region promoter of class 1 integrons. The detection rates of intI1-positive and intI1-negative isolates in ICU, neurosurgery and other clinical departments were statistically different ( P<0.05). The resistance rate of intI1-positive isolates to some commonly used antibiotics was significantly higher than that of intI1-negative isolates ( P<0.05). qnrS gene was the prevalent PMQR gene. The detection rates of integrons and PMQR genes in Klebsiella aerogenes isolates was low except for the strains isolated in 2016. Conclusions:Antimicrobial resistance in Klebsiella aerogenes was closely related to integrons. The distribution of integrons in Klebsiella aerogenes strains isolated from different clinical departments was different, and the monitoring of drug-resistant strains should be strengthened in ICU and neurosurgery. The resistance to quinolones in Klebsiella aerogenes strains in this region was mainly related to qnrS gene.

Design,synthesis,and evaluation of fluoroquinolone derivatives as microRNA-21 small-molecule inhibitors / 药物分析学报

MicroRNA-21(miRNA-21)is highly expressed in various tumors.Small-molecule inhibition of miRNA-21 is considered to be an attractive novel cancer therapeutic strategy.In this study,fluoroquinolone de-rivatives Al-A43 were synthesized and used as miRNA-21 inhibitors.Compound A36 showed the most potent inhibitory activity and specificity for miRNA-21 in a dual-luciferase reporter assay in HeLa cells.Compound A36 significantly reduced the expression of mature miRNA-21 and increased the protein expression of miRNA-21 target genes,including programmed cell death protein 4(PDCD4)and phos-phatase and tensin homology deleted on chromosome ten(PTEN),at 10 uM in HeLa cells.The Cell Counting Kit-8 assay(CCK-8)was used to evaluate the antiproliferative activity of A36;the results showed that the IC50 value range of A36 against six tumor cell lines was between 1.76 and 13.0 μM.Meanwhile,A36 did not display cytotoxicity in BEAS-2B cells(lung epithelial cells from a healthy human donor).Furthermore,A36 significantly induced apoptosis,arrested cells at the G0/G1 phase,and inhibited cell-colony formation in HeLa cells.In addition,mRNA deep sequencing showed that treatment with A36 could generate 171 dysregulated mRNAs in HeLa cells,while the expression of miRNA-21 target gene dual-specificity phosphatase 5(DUSP5)was significantly upregulated at both the mRNA and protein levels.Collectively,these findings demonstrated that A36 is a novel miRNA-21 inhibitor.

Comparative analysis of the detection and control standards for quinolone residues in animal-derived foods and supervision among multiple regulatory sectors / 上海预防医学

In order to compare the standards for quinolone residues in animal-derived food in China and supervision among multiple regulatory sectors， we summarized and compared the current standards for the limits of quinolone residues in animal-derived food in China and sampling examination strategy among regulatory sectors. There were defects in the standard limits of lomefloxacin， pefloxacin， ofloxacin， and norfloxacin which have been banned by the Ministry of Agriculture and Rural Affairs. In addition， the determination limits of those indexes in the supervision remain inconsistent across multiple regulatory sectors. Multiple regulatory sectors on food safety should perform further risk assessment on the above problems and formulate the standards for the limits of quinolone residues in animal-derived food that may be applicable in China.

Health risk assessment of multiple antibiotic residues in meat and meat products in Shanghai from 2016 to 2020 / 上海预防医学

Objective:To determine the current status of multiple antibiotic residues in meat and meat products in Shanghai based on a 5-year surveillance， and perform the health risk assessment. Methods:We performed the examination in accordance with the Manual for National Food Contamination and Harmful Factor Risk Monitoring， and conduct health risk assessment according to the national limit standards on the monitoring data of 2016‒2020. Results:The total detection rate of multiple antibiotics in meat and meat products in Shanghai was determined to be 16.03%， in which the total unqualified rate was 1.97%. Moreover， the detection rate of quinolones was 2.78% and its unqualified rate was 0.83%. The unqualified rate of loxacin in cooked meat products was 2.12%. The detection rate of tetracyclines was 17.06% and its unqualified rate was 0.34%， in which the highest detection rate was identified in doxycycline （11.64%）. The detection rate of sulfonamides was 3.16%， in which the highest detection rate was in sulfamethazine （1.05%）. The detection rate of florfenicol was 5.15% and its unqualified rate was 0.12%. The difference of ofloxacin residues between diverse food categories （χ2=17.44， P<0.05） and processing links （χ2 =14.10， P<0.05） was statistically significant. In addition， the sum amount of ofloxacin， enrofloxacin and ciprofloxacin in cooked meat products was higher than other food categories； the unqualified rate and residual amount of ofloxacin available in online stores and catering links were both higher. The residual amount of doxycycline and the unqualified rate in the online store link were significantly higher than those in other links. Based on preliminary assessment， the high exposure values in the 97.5 percentile of meat and meat products accounted for a very low proportion of the corresponding acceptable daily intake （ADI） and posed a low health risk to the population. Conclusion:The total detection rate of tetracyclines in meat and meat products is relatively high， which obviously accumulates in the offals of livestock and poultry. In addition， some antibiotics， such as ofloxacin and doxycycline， are relatively high in catering and online stores. It is recommended to strengthen the supervision of quinolones in cooked meat products， especially ofloxacin， enrofloxacin， and ciprofloxacin， and improve the supervision of doxycycline in meat and meat products in online stores.

Analysis of serum and drug resistance levels between food source and human salmonella / 公共卫生与预防医学

Objective To analyze serotype distribution, drug resistance, quinolone resistance gene carrying status and genetic relationship of foodborne Salmonella and human Salmonella isolates in Changzhou from 2012 to 2018, to provide scientific basis for the prevention and control of Salmonella. Methods The serum type was identified by serum agglutination and liquid chip. The antibiotic sensitivity was determined by micro broth dilution method. The quinolone antibiotic resistance gene was determined by gene sequencing method. The multilocus sequence typing ( MLST ) typing was performed on quinolone-resistant Salmonella, and the genetic relationship was analyzed by BioNumerics 8.0. Results A total of 10 and 36 serotypes were detected in 46 foodborne Salmonella strains and 152 human Salmonella strains, respectively. The dominant serotypes were Indiana Salmonella and Salmonella typhimurium. Erythromycin resistance rate was the highest in both Salmonella strains, and the proportion of multidrug-resistant bacteria was 93.47 % ( 43 / 46 ) and 80.92 % ( 123 / 152 ), respectively. 38 strains of quinolone-resistant foodborne Salmonella GyrA subunit mainly occurred double mutations Asp87Asn, Ser83Phe, ParC subunit mainly occurred single mutation Ser80Arg, 119 strains of quinolone-resistant human Salmonella qnrS gene detection rate was higher, reached 68.1 % ( 81 / 119 ) ; The dominant ST types of quinolone-resistant Salmonella from two sources were ST17 and ST19, respectively. Conclusions The antibiotic sensitivity of the two Salmonella resistant strains from Changzhou was the same ; Synergistic drug resistance, but both quinolone resistance genemutations and carry inconsistent ; The ST type distribution of quinolone resistant strains isalso inconsistent, and the genetic relationship is far. It is suggested that the probability of Salmonella resistant bacteria infection caused by food transmission in our region is small, and the treatment of the two should be differentiated.

Research progress of new antimicrobial agents for drug-resistant pathogenic bacteria / 中华临床感染病杂志

This article reviews the status quo of new antimicrobial agents that have been approved or undergoing phase Ⅱ/Ⅲ clinical trials in last five years at home and abroad, including new β-lactamase inhibitors and their compound preparations, oxazolidinones, tetracyclines, aminoglycosides, glycopeptides, quinolones, new antifungal agents, cyclic lipopeptides and new anti-mycobacterial agents. The antibacterial activities, main mechanisms of drug resistance, and progress of clinical studies of 27 new drugs were introduced to provide a reference for their clinical application.

A Novel Mismatched PCR-Restriction Fragment Length Polymorphism Assay for Rapid Detection of gyrA and parC Mutations Associated With Fluoroquinolone Resistance in Acinetobacter baumannii

BACKGROUND: Mutations in the quinolone resistance-determining regions (QRDRs) of Acinetobacter baumannii DNA gyrase (gyrA) and topoisomerase IV (parC) are linked to fluoroquinolone (FQ) resistance. We developed a mismatched PCR-restriction fragment length polymorphism (RFLP) assay to detect mutations in the gyrA and parC QRDRs associated with FQ resistance in A. baumannii. METHODS: Based on the conserved sequences of A. baumannii gyrA and parC, two primer sets were designed for mismatched PCR-RFLP to detect mutations in gyrA (codons 83 and 87) and parC (codons 80 and 84) by introducing an artificial restriction enzyme cleavage site into the PCR products. This assay was evaluated using 58 A. baumannii strains and 37 other Acinetobacter strains that have been identified by RNA polymerase β-subunit gene sequence analysis.

Mismatch amplification mutation assay-polymerase chain reaction: A method of detecting fluoroquinolone resistance mechanism in bacterial pathogens

The mismatch amplification assay is a modified version of polymerase chain reaction (PCR) that permits specific amplification of gene sequences with single base pair change. The basis of the technique relies on primer designing. The single nucleotide mismatch at the 3' proximity of the reverse oligonucleotide primer makes Taq DNA polymerase unable to carry out extension process. Thus, the primers produce a PCR fragment in the wild type, whereas it is not possible to yield a product with a mutation at the site covered by the mismatch positions on the mismatch amplification mutation assay (MAMA) primer from any gene. The technique offers several advantages over other molecular methods, such as PCR-restriction fragment length polymorphism (RFLP) and oligonucleotide hybridization, which is routinely used in the detection of known point mutations. Since multiple point mutations in the quinolone resistance determining region play a major role in high-level fluoroquinolone resistance in Gram-negative bacteria, the MAMA-PCR technique is preferred for detecting these mutations over PCR-RFLP and sequencing technology.

Next-generation strategy for treating drug resistant bacteria: Antibiotic hybrids

Resistance against nearly all antibiotics used clinically have been documented in bacteria. There is an ever-increasing danger caused by multidrug-resistant Gram-negative bacteria in both hospital and community settings. In Gram-negative bacteria, intrinsic resistance to currently available antibiotics is mainly due to overexpressed efflux pumps which are constitutively present and also presence of protective outer membrane. Combination therapy, i.e., use of two or more antibiotics, was thought to be an effective strategy because it took advantage of the additive effects of multiple antimicrobial mechanisms, lower risk of resistance development and lower mortality and improved clinical outcome. However, none of the benefits were seen in in vivo studies. Antibiotic hybrids are being used to challenge the growing drug resistance threat and increase the usefulness of current antibiotic arsenal. Antibiotic hybrids are synthetic constructs of two molecules which are covalently linked. These could be two antibiotics or antibiotic with an adjuvant (efflux pump inhibitor, siderophore, etc.) which increases the access of the antibiotics to the target. The concepts, developments and challenges in the future use of antibiotic hybrids are discussed here. Majority of the studies have been conducted on fluoroquinolones and aminoglycosides molecules. The antibiotic tobramycin has the property to enhance the action of antimicrobial agents against which the multidrug-resistant Gram-negative bacteria were earlier resistant, and thus potentiating the action of legacy antibiotics. Antibiotic hybrids may have a role as the silver bullet in Gram-negative bacteria to overcome drug resistance as well as extend the spectrum of existing antibiotics

Plasmid-mediated fluoroquinolone resistance associated with extra-intestinal Escherichia coli isolates from hospital samples

Background & objectives: Infection from fluoroquinolone-resistant extra-intestinal Escherichia coli is a global concern. In this study, isolation and characterization of fluoroquinolone-resistant extra-intestinal E. coli isolates obtained from hospital samples were undertaken to detect plasmid-mediated quinolone resistance (PMQR) genes. Methods: Forty three isolates of E. coli obtained from patients with extra-intestinal infections were subjected to antibiogram to detect fluoroquinolone resistance. The mechanism of fluoroquinolone resistance was determined by the detection of PMQR genes and mutations in quinolone resistance determining region (QRDR). Results: Of the 43 isolates, 36 were resistant to nalidixic acid (83.72%) and 28 to ciprofloxacin (65.11%). Eight E. coli isolates showed total resistance to both the antimicrobials without any minimum inhibitory concentration. The detection of PMQR genes with qnr primers showed the presence of qnrA in two, qnrB in six and qnrS in 21 isolates. The gene coding for quinolone efflux pump (qepA) was not detected in any of the isolates tested. The presence of some unexpressed PMQR genes in fluoroquinolone sensitive isolates was also observed. Interpretation & conclusions: The detection of silent PMQR genes as observed in the present study presents a risk of the transfer of the silent resistance genes to other microorganisms if present in conjugative plasmids, thus posing a therapeutic challenge to the physicians. Hence, frequent monitoring is to be done for all resistance determinants.

Distribution of Plasmid-Mediated Quinolone Resistance, Integrons and AdeABC Efflux Pump Genes in Nosocomial Isolates of Acinetobacter baumannii

Background: Acinetobacter baumannii is anopportunistic pathogen associated with nosocomialinfections. Extensive use of quinolones has resulted inan increase of resistance in this organism worldwide.Aim and Objectives: To study the association betweenPMQR genes, integron carriage as well as the possiblerole of AdeABC efflux pump in ciprofloxacinresistance as well as multidrug resistance in clinicalisolates of A. baumannii. We studied the presence ofPlasmid-Mediated-Quinolone Resistance (PMQR);AdeABC efflux pump genes and integron carriage inIntensive Care Unit (ICU) isolates of A. baumannii.Material and Methods: Fifty six non-duplicate clinicalisolates of A. baumannii were obtained from twoth th hospital ICUs in Tehran from March 5 2014 to July 202015. Susceptibility to 10 antibiotics was determinedby disc diffusion. Presence of PMQR (aac(6')-Ib-cr,qnrA, qnrB, qnrC, qnrD and qnrS), adeABC efflux andclass I and II integron genes were detected byPolymerase Chain Reaction (PCR). Results: Allisolates were Multidrug-Resistant (MDR) amongwhich, qnrB and aac(6')-Ib-cr were detected in 7.1%and 26.8% of the isolates, respectively. However, qnrA,qnrC, qnrD and qnrS were not observed. Presence ofadeA and adeB was observed in 100% and adeC in73.2% of the isolates. Overall, integron carriage wasobserved in (94.6%) of the isolates including qnrBpositive and 73.3% of the aac(6')-Ib-cr carryingisolates. Conclusion: Our results show that quinoloneresistance is not associated with PMQR genes. On theother hand, the AdeABC efflux pump is clearlyresponsible for MDR in our A. baumannii isolates including resistance to quinolones. No association wasfound between PMQR and integron carriage.

Recent Developments And Multiple Biological Activities Available With 1, 8-Naphthyridine Derivatives: A Review

Within the wide range of nitrogen-containing heterocyclic compounds, the derivatives of 1,8-naphthyridine (NPTR) have gained a rising interest due to their reported versatile biological activities. The derivatives of NPTR scaffold are found to invite special interest from researchers nowadays on the significance of their manifestations of multiple attractive pharmacological activities which establish them as an effective and versatile tool in pharmaceutical chemistry and drug discovery. The diverse biological activities mainly include anti-inflammatory, antimicrobial, antiviral, anticancer, antihypertensive and analgesic activities. Novel NPTR scaffold has emerged its potency to treat neurological diseases like depression and Alzheimer's disease. Further these agents possess different inhibitory activities, such as anti-HIV, anti-osteoporotic, αvβ3 antagonism, antimalarial, platelet aggregation, anti-oxidant, anti-allergic, gastric antisecretory, anticonvulsant, epidermal growth factor receptor (EGFR) inhibition, protein kinase inhibition, ionotropic properties, β3 antagonism, phosphodiesterase 4 (PDE 4) inhibitions, adenosine receptor agonistic activity, adrenoceptors antagonism and DNA stabilizing activity, etc. In this review, we highlight the updates of different 1,8-naphthyridine derivatives and explain the key data available in the context of various biological activities of NPTR derivatives available from the literature. This may direct opportunity in researches in the synthesis of novel medicinal agents and the development of new heterocycles for modification of existing biological actions as well as evaluation of other possible pharmacological activities.

Rapid Identification of Alkaloids in Evodia rutaecarpa by HPLC-Q-TOF-MS/MS / 中国实验方剂学杂志

Objective:To obtain the information of alkaloids in Evodia rutaecarpa by HPLC-Q-TOF-MS/MS. Method:Inter Sustain-C18 column (4.6 mm×250 mm,5 μm) was used with 0.2% formic acid water-acetonitrile as the mobile phase for gradient elution. The column temperature was 25℃,the volume flow rate was 1.0 mL·min-1,and the sample volume is 5 μL. The detection wavelength was 245 nm,and the chromatographic effluent was detected and analyzed by using both positive and negative ions. Result:According to molecular ion peaks and secondary mass spectrometry characteristic fragment ions,as well as the mass spectrometry information of reference substances and relevant literature reports,more than 40 major peaks were analyzed,and 21 alkaloids were identified from the methanol extract of E. rutaecarpa, including 10 kinds of indole alkaloids,10 kinds of quinolone alkaloids,and 1 kind of ephedrine. Main types of alkaloids in E. rutaecarpa were basically clarified. And the research found that the alkaloids have a good response mainly in the positive mode. Conclusion:Based on HPLC-Q-TOF-MS/MS technology, high-performance liquid chromatography (HPLC) separation,mass spectrometry determination of molecular mass,pyrolysis data,literature analysis and retrieval were performed to quickly,accurately and comprehensively identify alkaloids in E. rutaecarpa, so as to provide a scientific basis for the further extraction and separation of the chemical constituents of E. rutaecarpa.

Synthesis and Antibacterial Activity of Novel 7-Phosphoryl Quinolone Derivatives / 中国药学杂志

OBJECTIVE: To search more effective antibacterial candidate agents by designing a series of 7-phosphoryl quinolone derivatives,exploring the synthetic methods, and evaluating their antibacterial activities. METHODS: The quinolone derivatives were synthesized using phosphate and quinolone intermediates as raw materials and alkaline ionic liquid [Bmim] OH as catalyst with microwave assistance. The antibacterial activities of the products were evaluated by agar dilution method. RESULTS: Eight title compounds were prepared, and their structures were clearly established by IR, NMR and MS. The in vitro experiment showed that the derivatives had potential antibacterial activity. Especially, compound Ⅱc showed more potent activities against S. aureus, E. coli, MREC-1# and MREC-2# with minimum inhibitory concentrations (MICs) of 1.6, 6.4, 12.8,6.4 mg•mL-1, respectively, and the MICs of compound Ⅱ gagainst S. aureus, E. coli, MREC-1# and MREC-2# were 1.6, 3.2, 6.4, 6.4 mg•mL-1, respectively. Its activity on drug-resistant bacteria was better than that of the control drug norfloxacin. CONCLUSION: The quinolone derivatives are highly active on drug-resistant bacteria.It is worth of further study.

Mechanisms of quinolone resistance of carbapenem-resistant Enterobacteriaceae / 中国感染控制杂志

Objective To study the prevalence of plasmid-mediated quinolone resistance (PMQR) genes in carbapenem-resistant Enterobacteriaceae (CRE) and its resistance mechanism.Methods Clinically isolated CRE strains in a hospital from March 2015 to March 2018 were collected, then identified and performed antimicrobial susceptibility test by VITEK2 Compact analyzer, carriage of PMQR genes qnrA, qnrB, qnrS, qepA and acc (6') Ib-cr were determined by polymerase chain reaction (PCR) and sequencing, the horizontal transfer of PMQR genes were verified by plasmid conjugation test.Results Resistance rates of carbapenem-resistant Escherichia coli and carbapenem-resistant Klebsiella pneumoniae to quinolones were 100％ and 15.56％-33.33％ respectively.Detection rate of acc (6') Ib-cr gene was the highest (87.72％), followed by qnrB (77.19％) and qnrS (17.54％), 2 strains (3.51％) carried qnrA gene, qepA gene was not isolated, 84.21％ of strains harbored 2 or 3 PMQR genes.PMQR gene was transfected into all the 8 conjugated strains, but minimum inhibitory concentration value of quinolones didn't change significantly.Conclusion The detection rate of PMQR genes in CRE in this hospital is high, but there is a certain sensitivity to quinolones.

Molecular characteristics of qnrS1-positive Escherichia coli resistant to quinolone / 中华微生物学和免疫学杂志

Objective To analyze the molecular characteristics of qnrS-positive Escherichia coli ( E. coli) strains resistant to quinolone. Methods A total of 57 qnrS1-positive clinical isolates were collect-ed from Fujian Medical University Union Hospital. Plasmid-mediated quinolone resistance ( PMQR) genes [qnrA, qnrB, qnrC, qnrD, aac(6′)-Ib-cr, qepA and oqxAB] andβ-lactamase genes (blaCTX-M-1, blaCTX-M-2, blaCTX-M-8 , blaCTX-M-9 , blaSHV and blaTEM ) were detected by PCR and then sequenced. Agar dilution method was used to analyze the antimicrobial susceptibility of the qnrS1-positive strains. Phylogenetic analysis was conducted using PCR. Multilocus sequence typing ( MLST) was performed for phenotyping. Enterobacterial repetitive intergenic consensus-polymerase chain reaction ( ERIC-PCR) was used to evaluate the genetic sim-ilarity between those isolates. Transferability of the qnrS1 genes carried by the 57 strains was examined by conjugation test with the sodiumazide-resistant E. coli J53 as the recipient strain. Mutations in the quinolone resistance-determining regions ( QRDR) in those strains were analyzed by PCR. Results All of the qnrS1-positive E. coli strains showed high resistance to quinolones. PMQR genes were harbored by 14 (24. 6％) isolates. Extended spectrum β-lactamases (ESBLs)-producing isolates accounted for 68. 4％. Mutations in the QRDR of gyrA, gyrB, parC and parE genes were found in 56 (98. 2％) strains and the most frequent point mutations were S83L (89. 5％) in gyrA gene, S80I (54. 4％) in parC gene and P415V (28. 1％) in parE gene. The qnrS1 gene was successful transferred from 13 (22. 8％) isolates to E. coli J53 by conjuga-tion. Five plasmid incompatibility groups were detected. Phylogenetic analysis showed that there were 36 (63. 2％), 13 (22. 8％), 1 (1. 8％) and 7 (12. 3％) isolates belonging to groups A, B1, B2 and D, respectively. The 57 qnrS1-positive E. coli strains were assigned to 50 ERIC types and 39 sequence types ( ST) based on the results of ERIC-PCR and MLST. Conclusions Mutations in the QRDR in E. coli strains were associated with qnrS1 gene and might play a critical role in the dissemination of quinolone-resistant bacteria.

Synthesis Of Novel Heterocyclic Quinolone Compound For Anti -tubercular Activity

In last few decades, though significant progress has been made in the treatment and control strategies of tubercular infections by introducing new diagnostic and monitoring tools and combination therapy, it still continues to be se-vere problem. The need of study was only because of there are many drugs in market to treat infection but most of the drugs are showing resistance because of the same it is difficult to treat the infection. In this study we chosen quinolone nucleus for study and over it. Thus with the aim of developing novel molecule with improved potency for treating Mycobacterium tuberculosisH37Rv strain infections and with decreased probability of developing drug re-sistance. Methodology:The synthesis of Quinolone derivatives, starting from substituted aniline and ethyl acetoace-tate, by conventional organic reaction and results of investigations of their anti-mycobacterial activity.Results: MICs of the synthesized compounds are compared with existing drugs Cytotoxicity. The substituted quinolones are synthe-sized by taking mixture of7-substituted-2-(3-chloro-2-oxopropyl) quinolin-4(1H)-one and different secondary amines. Many compounds have shown promising activity while some were inactive. Conclusion:It was found that Compound A1,A3,B1,B3,have shown promising anti tubercular activity whereas compound A2, A4,B2,B4were showing moderate anti tubercular activity against std. Streptomycin.

Observation of a new pattern of mutations in gyrA and parC within Escherichia coli exhibiting fluroquinolone resistance

Therapeutic options with quinolones are severely compromised in infections caused by members of Enterobacteriaceae family. Mutations in chromosomal region are one of the major reasons for bacterial resistance towards this group of antibiotic. The aim of the study is to detect the mutations in gyr A and par C responsible for quinolone resistance among clinical isolates of Escherichia coli. A total of 96 quinolone-resistant clinical isolates of E. coli were collected from a tertiary care hospital of North-east India during March 2015 to August 2015. All the quinolone-resistant E. coli strains were investigated for mutations in the topoisomerases genes gyrA and parC by amplifying and sequencing the quinolone resistance determining regions. Among the 96 E. coli isolates, 83.3% were resistant to nalidixic acid and 80.2%, 66.6%, 23.9% and 50% to ciprofloxacin, norfloxacin, levofloxacin and ofloxacin, respectively. Several alterations were detected in gyrA and parC genes. Three new patterns of amino acid substitution are reported in E. coli isolates. The findings of this study warrant a review in quinolone-based therapy in this region of the world to stop or slow down the irrational use this drug.