I= GENETIC ANALYSIS OF MULTI DRUG RESISTANT STRAINS OF SALMONELLA TYPHI ISOLATED IN KARACHI, PAKISTAN
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Title of Thesis
GENETIC ANALYSIS OF MULTI DRUG RESISTANT STRAINS OF SALMONELLA TYPHI ISOLATED IN KARACHI, PAKISTAN

Author(s)
Bader Jehan Farooqui
Institute/University/Department Details
Department of Genetics/ University of Karachi
Session
Subject
Genetics
Number of Pages
301
Keywords (Extracted from title, table of contents and abstract of thesis)
salmonella typhi, genetic analysis, typhoid fever, cefotaxime, ceftriaxone, aztreonam, ofloxacin, plasmid pbnl

Abstract
Over a period of seven years (1986-1992) 2,935 S. typhi were isolated from blood cultures collected from patients suspected of typhoid fever. During this study period S. typhi was observed to circulate in each month of every year, with the number of isolates increasing each year.

MDR S. typhi causing typhoid fever has existed in Karachi since July 1986. The frequency of isolation, however, of MDR S. typhi causing typhoid fever has increased over a period of seven years. This increase is statistically significant when the numbers of MDR S. typhi isolated in 1992 are compared with those in 1986. There was a sharp increase in the frequency of isolation of MDR S. typhi in the year 1987, but the total number of resistant isolates were less than in 1992 Our results show that MDR S. typhi responsible for typhoid fever are still sensitive to cefotaxime, ceftriaxone, aztreonam and ofloxacin with a narrow range of MICs.

Acridine orange and ethidium bromide failed to cure the antimicrobial resistance markers of MDR S. typhi. These MDR S. typhi isolates appear to share a single plasmid (named pBN1) of 20 Kb which confers resistance to chloramphenicol, ampicillin and trimethoprim sulfamethoxazole. Plasmid of all these MDR S. typhi when treated with EcoRl produced single band indicating that these plasmids have no restriction sites for EcoRl.

These results confirm that the plasmid pBNl is responsible for the resistance to all the three antimicrobial drugs. The results also confirm that plasmid pBNl is conjugative in nature.

The results have demonstrated that E. coli HB10l was successfully transformed with plasmid pBN1. Transformed E. coli HB10l showed same antimicrobial resistance pattern and MICs as donor cells.

Transconjugants and transformed E. coli carried same resistance markers as that of the donor cells. Plasmid of transconjugants and transformed E. coli when treated with EcoRl produced single band indicating that these plasmids have no restriction sites for EcoRl.

To conclude it is perhaps a single plasmid which is responsible for the cause of resistance in all the strains of S. typhi.

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1772.33 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
142.74 KB
2 1 Introduction 4
42.58 KB
3 2 Literature Review 9
405.41 KB
  2.1 The Background Of The Organism 9
  2.2 Classification 10
  2.3 Antigenic Characteristics 13
  2.4 Morphological And Cultural Characteristics 15
  2.5 Identification 16
  2.6 Antibiotic Susceptibility Testing 17
  2.7 Virulence 20
  2.8 Epidemiology 24
  2.9 Infective Dose Of Salmonella 25
  2.10 Gastroenteritis 29
  2.11 Treatment Of Gastroenteritis And Focal Abscesses 36
  2.12 Treatment Of Typhoid Fever 37
  2.13 Mechanism Of Acquiring Drug Resistant In S. Typhi 45
4 3 Materials And Methods 71
240.11 KB
  3.1 Collection Of Blood Samples By Standard Technique 72
  3.2 Culture And Isolation Of S. Typhi 73
  3.3 Biochemical Identification Of S. Typhi With Api 20e Strip 74
  3.4 Serological Identification Of S. Typhi 77
  3.5 Sensitivity/ Resistant Of S. Typhi Isolates To Antimicrobial Compounds 79
  3.6 Mics Of Antimicrobial Agents For Mdr S. Typhi 83
  3.7 Curing Of Mdr S. Typhi Plasmid Dna With Acridine Orange And Ethidium Bromide 88
  3.8 Mdr S. Typhi Plasmid Isolation 91
  3.9 Mdr S. Typhi Digestion With Ecor1 97
  3.10 Conjugation Of Mdr S. Typhi With E. Coli Nctc 10418 100
  2.11 Sensitivity/ Resistance Of Transconjugants E. Coli To Antimicrobial Compounds 103
  3.12 Mics Of Antimicrobial Agents Fro Transconjugants E. Coli 104
  3.13 Transconjugants E. Coli Plasmid Isolation 105
  3.14 Transconjugants E. Coli Plasmid Digestion With Ecor1 106
  3.15 Transformation Of Mdr S. Typhi Plasmid E. Coli Hb101 107
  3.16 Sensitivity/ Resistance Of Transformation E. Coli To Antimicrobial Compounds 110
  3.17 Mics Of Antimicrobial Agents For Transformed E. Coli 111
  3.18 Transformed E. Coli Plasmid Isolation 112
  3.19 Transformed E. Coli Hb101 Plasmid Digestion With Ecor1 113
5 4 Results 114
716.5 KB
  4.1 Growth Of S. Typhi On Macconeky ’s Agar Medium 114
  4.2 Biochemical Identification Of S. Typhi With Api 20e Strips 116
  4.3 Serological Identification Of S. Typhi 121
  4.4 Rate Of S. Typhi Isolated From Blood Cultures During 1986-1992 123
  4.5 Sensitivity/ Resistance Of S. Typhi Isolates To Antimicrobial Compounds 136
  4.6 Rate Of Mdr S. Typhi Isolated From Blood Cultures During 1986-1992 141
  4.7 The Mics Of Antimicrobial Agents For Mdr S. Typhi 154
  4.8 Curing Of Mdr S. Typhi Plasmid With Acridine Orange And Ethidium Bromide 157
  4.9 Mdr S. Typhi Plasmid Isolated 159
  4.10 Mdr S. Typhi Plasmid Digestion With Ecor1 175
  4.11 Conjugation Of Mdr S. Typhi With E. Coli Nctc 10418 178
  4.12 Sensitivity/ Resistance Of Transconjugants E. Coli To Antimicrobial Compounds 187
  4.13 Mics Of Antimicrobial Agents For Transconjugants E. Coli 191
  4.14 Transconjugants E. Coli Plasmid Isolation 194
  4.15 Transconjugant E. Coli Plasmid Digestion With Ecor1 199
  4.16 Transformation Of E. Coli Hb101 With Mdr S. Typhi Plasmid 201
  4.17 Sensitivity/ Resistance Of Transformated E. Coli To Antimicrobial Compounds 204
  4.18 Mics Of Antimicrobial Agents Fro Transformed E. Coli 208
  4.19 Transformed E. Coli Plasmid Isolation 221
  4.20 Transformed E. Coli Plasmid Digestion With Ecor1 214
  4.21 Characteristics Of Plasmid P Bn1 216
6 5 Discussion 217
281.48 KB
  5.1 Prevalence Of S. Typhi In Karachi 218
  5.2 Possible Source Of S. Typhi 220
  5.3 Prevalence Of Mdr S. Typhi In Karachi 230
  5.4 Treatment Of Mdr Typhoid Fever 236
  5.5 Factors Responsible For The Emergence Of Mdr S. Typhi In Karachi Pakistan 237
  5.6 Genetics Of Drug Resistance In Mdr S. Typhi 238
  5.7 Characters Of Plasmid Pbn1 224
  5.8 Transformation Of Pbn1 Plasmid 248
  5.9 Guidelines Recommendations 249
7 6 Conclusion 251
22.67 KB
8 7 Bibliography 254
300.03 KB