scholarly journals The Molecular Study of Antibiotic Resistance to Quinolones in Salmonella enterica Strains Isolated in Tehran, Iran

2017 ◽  
Vol 11 (1) ◽  
pp. 189-194 ◽  
Author(s):  
Shirin Malehmir ◽  
Reza Ranjbar ◽  
Naser Harzandi
Keyword(s):  
Nalidixic Acid ◽  
Salmonella Enterica ◽  
Gastrointestinal Disease ◽  
Medical Center ◽  
Molecular Study ◽  
Quinolone Resistance ◽  
Microbiological Methods ◽  
Increased Risk ◽  
High Prevalence ◽  
S Genes

Introduction:Salmonellais known as one of the most important causes of gastrointestinal disease in the world. Quinolones and fluoroquinolones are used successfully in the treatment of salmonellosis particularly for infections that have become resistant to several antibiotics. But non-susceptible isolates to quinolones have been reported in several countries. The data are limited about the prevalence of quinolone-resistant isolates in our country. Therefore, this study investigated the plasmid-mediated quinolone resistance genes inSalmonella entericaisolated in Children's Medical Center in Tehran during 2014-2015.Methods and Materials:Salmonellaisolates were isolated and identified using standard microbiological methods. Antibiotic susceptibility testing and screening ofSalmonellastrains resistant to quinolones were performed according to the CLSI guidelines. The molecular investigation was done using specific primers for detection of qnr genes including:qnrA,qnrB andqnrS, by polymerase chain reaction.Results:Overall, 92 (66.6%) strains were resistant to nalidixic acid. None of the strains showed resistance to ciprofloxacin. Out of the 92 nalidixic acid resistant strains, 52 (56.52%) harboredqnrS genes, 15 strains (16.30%) had bothqnrA andqnrS genes. Two (1.1%) isolates were positive forqnrB gene. Twenty four (26.08%) nalidixic acid resistant isolates did not have any qnr qens.Conclusion:The results of this study show high prevalence of resistance to nalidixic and qnr genes inSalmonellaisolates. Plasmid nature of this type of resistance poses an increased risk of dissemination of quinolone resistance betweenSalmonellaand non-Salmonellaisolates circulating in hospitals environments.

scholarly journals High prevalence of plasmid-mediated quinolone resistance determinants in commensal members of the Enterobacteriaceae in Ho Chi Minh City, Vietnam

2009 ◽  
Vol 58 (12) ◽  
pp. 1585-1592 ◽  
Author(s):  
Le Thi Minh Vien ◽  
Stephen Baker ◽  
Le Thi Phuong Thao ◽  
Le Thi Phuong Tu ◽  
Cao Thu Thuy ◽  
...  
Keyword(s):  
Nalidixic Acid ◽  
Intestinal Flora ◽  
Hospitalized Patients ◽  
Quinolone Resistance ◽  
Ho Chi Minh City ◽  
Healthy Individuals ◽  
Resistance Mutations ◽  
Resistance Determinants ◽  
Antimicrobial Resistance Genes ◽  
High Prevalence

Antimicrobial-resistant pathogenic members of the Enterobacteriaceae are a well-defined global problem. We hypothesized that one of the main reservoirs of dissemination of antimicrobial resistance genes in Vietnam is non-pathogenic intestinal flora, and sought to isolate antimicrobial-resistant organisms from hospitalized patients and non-hospitalized healthy individuals in Ho Chi Minh City. The results identified substantial faecal carriage of gentamicin-, ceftazidime- and nalidixic acid-resistant members of the Enterobacteriaceae in both hospitalized patients and non-hospitalized healthy individuals. A high prevalence of quinolone resistance determinants was identified, particularly the qnrS gene, in both community- and hospital-associated strains. Furthermore, the results demonstrated that a combination of quinolone resistance determinants can confer resistance to nalidixic acid and ciprofloxacin, even in the apparent absence of additional chromosomal resistance mutations in wild-type strains and laboratory strains with transferred plasmids. These data suggest that intestinal commensal organisms are a significant reservoir for the dissemination of plasmid-mediated quinolone resistance in Ho Chi Minh City.

scholarly journals Development of a Pefloxacin Disk Diffusion Method for Detection of Fluoroquinolone-Resistant Salmonella enterica

2015 ◽  
Vol 53 (11) ◽  
pp. 3411-3417 ◽  
Author(s):  
Robert Skov ◽  
Erika Matuschek ◽  
Maria Sjölund-Karlsson ◽  
Jenny Åhman ◽  
Andreas Petersen ◽  
...  
Keyword(s):  
Nalidixic Acid ◽  
Salmonella Enterica ◽  
Quinolone Resistance ◽  
Disk Diffusion ◽  
Fluoroquinolone Resistance ◽  
Diffusion Method ◽  
Wild Type ◽  
Disk Diffusion Method ◽  
Content Type ◽  
Low Level

Fluoroquinolones (FQs) are among the drugs of choice for treatment ofSalmonellainfections. However, fluoroquinolone resistance is increasing inSalmonelladue to chromosomal mutations in the quinolone resistance-determining regions (QRDRs) of the topoisomerase genesgyrA,gyrB,parC, andparEand/or plasmid-mediated quinolone resistance (PMQR) mechanisms includingqnrvariants,aac(6′)-Ib-cr,qepA, andoqxAB. Some of these mutations cause only subtle increases in the MIC, i.e., MICs ranging from 0.12 to 0.25 mg/liter for ciprofloxacin (just above the wild-type MIC of ≤0.06 mg/liter). These isolates are difficult to detect with standard ciprofloxacin disk diffusion, and plasmid-mediated resistance, such asqnr, is often not detected by the nalidixic acid screen test. We evaluated 16 quinolone/fluoroquinolone disks for their ability to detect low-level-resistantSalmonella entericaisolates that are not serotype Typhi. A total of 153Salmonellaisolates characterized for the presence (n= 104) or absence (n= 49) ofgyrAand/orparCtopoisomerase mutations,qnrA,qnrB,qnrD,qnrS,aac(6′)-Ib-cr, orqepAgenes were investigated. All isolates were MIC tested by broth microdilution against ciprofloxacin, levofloxacin, and ofloxacin and by disk diffusion using EUCAST or CLSI methodology. MIC determination correctly categorized all isolates as either wild-type isolates (MIC of ≤0.06 mg/liter and absence of resistance genes) or non-wild-type isolates (MIC of >0.06 mg/liter and presence of a resistance gene). Disk diffusion using these antibiotics and nalidixic acid failed to detect some low-level-resistant isolates, whereas the 5-μg pefloxacin disk correctly identified all resistant isolates. However, pefloxacin will not detect isolates havingaac(6′)-Ib-cras the only resistance determinant. The pefloxacin disk assay was approved and implemented by EUCAST (in 2014) and CLSI (in 2015).

scholarly journals New Quinolone Resistance Phenomenon in Salmonella enterica: Nalidixic Acid-Susceptible Isolates with Reduced Fluoroquinolone Susceptibility

2005 ◽  
Vol 43 (11) ◽  
pp. 5775-5778 ◽  
Author(s):  
A. J. Hakanen ◽  
M. Lindgren ◽  
P. Huovinen ◽  
J. Jalava ◽  
A. Siitonen ◽  
...  
Keyword(s):  
Nalidixic Acid ◽  
Salmonella Enterica ◽  
Quinolone Resistance

Molecular study of quinolone resistance mechanisms and clonal relationship of Salmonella enterica clinical isolates

2014 ◽  
Vol 43 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Clara Ballesté-Delpierre ◽  
Mar Solé ◽  
Òscar Domènech ◽  
Jordi Borrell ◽  
Jordi Vila ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Molecular Study ◽  
Resistance Mechanisms ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Clonal Relationship ◽  
Relationship Of

scholarly journals Clonal Expansion May Account for High Levels of Quinolone Resistance in Salmonella enterica Serovar Enteritidis

2005 ◽  
Vol 71 (5) ◽  
pp. 2587-2591 ◽  
Author(s):  
Donna Kilmartin ◽  
D. Morris ◽  
C. O'Hare ◽  
G. Corbett-Feeney ◽  
M. Cormican
Keyword(s):  
Nalidixic Acid ◽  
Salmonella Enterica ◽  
Phage Type ◽  
Acid Resistance ◽  
Clonal Expansion ◽  
Quinolone Resistance ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Salmonella Serovars ◽  
Nalidixic Acid Resistance

ABSTRACT We have observed a high incidence of isolated nalidixic acid resistance in Salmonella enterica serovar Enteritidis isolates in Ireland, particularly isolates of phage type 1 (PT1). A group of nalidixic acid-resistant (n = 22) and nalidixic acid-susceptible (n = 28) isolates of serovar Enteritidis from multiple sites in Ireland were selected. Isolates were typed by pulsed-field gel electrophoresis (PFGE) with XbaI, and the MICs for nalidixic acid and ciprofloxacin were determined. Mutations associated with nalidixic acid resistance in clinical isolates and laboratory mutants of serovar Enteritidis and 32 nalidixic acid-resistant isolates of 15 other salmonella serovars were identified. PFGE had limited discriminatory power. A specific point mutation (G246T) associated with amino acid substitution Asp87Tyr in the quinolone resistance determining region of the gyrA gene accounted for 95% of all mutations in serovar Enteritidis and for all mutations in PT1 isolates. Greater diversity of mutations was observed among all non-Enteritidis salmonella serovars studied. Rates of nalidixic acid resistance in serovar Enteritidis may predominantly reflect clonal expansion after infrequent mutation or selection events.

ANTIMICROBIAL SUSCEPTIBILITY IN CULTURE POSITIVE ENTERIC FEVER

2019 ◽  
Vol 3 (7) ◽  
Author(s):  
Dr. Manish Kulshrestha ◽  
Dr. Anjali Kulshrestha
Keyword(s):  
Bone Marrow ◽  
Blood Culture ◽  
Nalidixic Acid ◽  
Antimicrobial Susceptibility ◽  
Salmonella Enterica ◽  
Enteric Fever ◽  
Multidrug Resistant ◽  
Bone Marrow Culture ◽  
Diffusion Method ◽  
Culture Positive

INTRODUCTION: Enteric fever includes typhoid and paratyphoid fever. Peak incidence is seen in children 5–15 years of age; but in regions where the disease is highly endemic, as in India, children younger than 5 years of age may have the highest infection rates. There are about 22 million new typhoid cases occur each year. Young children in poor, resource limited areas, who make up the majority of the new cases and there is a mortality figures of 215,000 deaths annually. A sharp decline in the rates of complications and mortality due to typhoid fever is observed as a result of introduction of effective antibiotic therapy since 1950s. MDR-ST became endemic in many areas of Asia, including India soon after multidrug-resistant strains of Salmonella enterica serotype typhi (MDR-ST) that were resistant to all the three first-line drugs then in use, namely chloramphenicol, amoxycillin and co-trimoxazole emerged in early 1990s. MATERIAL AND METHODS: Only blood culture or bone marrow culture positive cases were included. The patients with culture isolated enteric fever were included in the study. Antimicrobial susceptibility testing was carried out by disk diffusion method using antibiotic discs. The analysis of the antimicrobial susceptibility was carried out as per CLSI interpretative guidelines. RESULTS: A total of 82 culture positive cases were included in the present study. 80 culture isolates were from blood culture and 2 from the bone marrow culture. Salmonella entericasubspecies enterica serovartyphi (S typhi) was isolated from 67 (81.70%) patients while Salmonella enterica subspecies entericaserovarparatyphi (S paratyphi A) was isolated from 13 (15.85%) cases and 2 (2.44%) were Salmonella enterica subspecies entericaserovarschottmuelleri (S paratyphi B). Of the 82 cases 65(79.3%) isolates were resistant to ciprofloxacin, 17 (20.7%) were resistant to nalidixic acid, one (1.2%) case each was resistant to Cefotaxime and ceftriaxone, 2 (2.4%) were resistant to chloramphenicol, 10 (12.2%) were resistant and to cotrimoxazole 3 (3.7%) were resistant. CONCLUSION: In a culture positive cases 65(79.3%) isolates were resistant to ciprofloxacin and 17 (20.7%) were resistant to nalidixic acid. Multidrug resistant isolates were 65(79.3%).

Safety and efficacy of stereotactic radiosurgery for tumors of the spine

2004 ◽  
pp. 413-418 ◽  
Author(s):  
Deborah L. Benzil ◽  
Mehran Saboori ◽  
Alon Y. Mogilner ◽  
Ronald Rocchio ◽  
Chitti R. Moorthy
Keyword(s):  
Spinal Cord ◽  
Single Dose ◽  
Pain Relief ◽  
Total Dose ◽  
Stereotactic Radiosurgery ◽  
Medical Center ◽  
Primary Tumors ◽  
Content Type ◽  
Increased Risk ◽  
Fine Print

Object. The extension of stereotactic radiosurgery treatment of tumors of the spine has the potential to benefit many patients. As in the early days of cranial stereotactic radiosurgery, however, dose-related efficacy and toxicity are not well understood. The authors report their initial experience with stereotactic radiosurgery of the spine with attention to dose, efficacy, and toxicity. Methods. All patients who underwent stereotactic radiosurgery of the spine were treated using the Novalis unit at Westchester Medical Center between December 2001 and January 2004 are included in a database consisting of demographics on disease, dose, outcome, and complications. A total of 31 patients (12 men, 19 women; mean age 61 years, median age 63 years) received treatment for 35 tumors. Tumor types included 26 metastases (12 lung, nine breast, five other) and nine primary tumors (four intradural, five extradural). Thoracic tumors were most common (17 metastases and four primary) followed by lumbar tumors (four metastases and four primary). Lesions were treated to the 85 to 90% isodose line with spinal cord doses being less than 50%. The dose per fraction and total dose were selected on the basis of previous treatment (particularly radiation exposure), size of lesion, and proximity to critical structures. Conclusions. Rapid and significant pain relief was achieved after stereotactic radiosurgery in 32 of 34 treated tumors. In patients treated for metastases, pain was relieved within 72 hours and remained reduced 3 months later. Pain relief was achieved with a single dose as low as 500 cGy. Spinal cord isodoses were less than 50% in all patients except those with intradural tumors (mean single dose to spinal cord 268 cGy and mean total dose to spinal cord 689 cGy). Two patients experienced transient radiculitis (both with a biological equivalent dose (BED) > 60 Gy). One patient who suffered multiple recurrences of a conus ependymoma had permanent neurological deterioration after initial improvement. Pathological evaluation of this lesion at surgery revealed radiation necrosis with some residual/recurrent tumor. No patient experienced other organ toxicity. Stereotactic radiosurgery of the spine is safe at the doses used and provides effective pain relief. In this study, BEDs greater than 60 Gy were associated with an increased risk of radiculitis.

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