bacterial recontamination of hands following handwashing in india - carol devamani, lshtm alumna
DESCRIPTION
Carol Devamani describes her study of bacterial recontamination after handwashing with soap. The findings from her research project - conducted as part of her studies at the London School of Hygiene and Tropical Medicine - show that rural India is a highly contaminated environment.TRANSCRIPT
Bacterial recontamination of hands following handwashing and associated risk
factors in rural Andhra Pradesh, India
Carol Devamani
OverviewIntroduction
Palamaner, Andhra Pradesh, IndiaAimsFaecal Indicator Bacteria
MethodologyResultsStrengths & WeaknessesPlates Conclusion
IntroductionAims
Primary: Recontamination levels – HWWSSecondary: risk factors
Faecal Indicator BacteriaEscherichia coliEnterococcus :
Sherman’s Criteria
MethodologyCPS Agar
Urine samplesSampling Technique
Direct Finger ImpressionMain study : 14 mothers/caregiversSub-study:
cross sectional survey 122 participants
• Main study
MethodologyPhoto Archiving :
random number for each platePhoto after 24-hour incubationReading by one person of:
Number of contaminated fingers Overall colony count
Microbiological Testing of Colonies : CMC, Vellore
Data Analysis
RESULTS
Main Study
Distribution of the number of fingers contaminatedEnterococcus E. coli
5.5 3.6
05
1015
2025
Per
cent
0 100 200 300entcocolony
05
1015
20P
erce
nt
-2 0 2 4 6entcol2
020
40
60
Perc
ent
0 50 100 150 200 250ecolicolony
05
1015
20P
erce
nt
0 2 4 6 8ecolicol2
Log Colony CountEnterococcus
E.coli
2.3
1.6
Recontamination - EnterococcusFINGER COUNT
LOG COLONY COUNT
6.6
2.9
Recontamination: E.coliFINGER COUNT
LOG COLONY COUNT
3.5
1.7
Comparison between the handwashing and control arms at each time point (t-test)
Sub - Study
Effect of type of person and type of activity on number of fingers contaminated and log colony count of Enterococcus
Sub-study : Enterococcus
N
No. of fingers contaminated Log Colony Count
Difference* P value* Difference* P value*
Person
Male (reference) 23 - - - -
Female 65 1.64 0.011 0.69 0.013
Grandmother 34 0.47 0.512 0.42 0.175
Activity
None (reference) 19 - - - -
Child rearing 37 2.31
0.002 0.69 0.026
Food
preparation
12 2.47 0.014 1.31 0.008
Soil contact 24 0.81 0.286 0.16 0.559
Contact with
Agricultural
products/crops
6
0.14
0.912
0.58
0.332
Animal contact 10 1.37 0.228 0.46 0.362
Other 23 0.39 0.662 0.18 0.647
*univariate linear regression analysis
Sub-study: E.coliEffect of type of person and type of activity on number of
fingers contaminated and log colony count of Escherichia coli
N No. of fingers contaminated Log Colony Count
Difference* P value* Difference* P value*
Person
Male (reference) 23 - - - -
Female 65 0.29 0.623 0.24 0.467
Grandmother 34 0.95 0.148 0.48 0.188
Activity
None (reference) 19 - - - -
Child rearing 37 -0.14 0.834 0.27 0.464
Food preparation 12 1.41 0.163 1.23 0.031
Soil contact 24 0.87 0.269 0.45 0.181
Contact with Agricultural products/crops
6
2.49
0.083
2.15
0.006
Animal contact 10 1.66 0.105 1.15 0.016
Other 23 -0.54 0.505 -0.003 0.995
*univariate linear regression analysis
Strengths & WeaknessesStrengths WeaknessesSimplicity of Method
No further testing Only need IncubatorNo additional personnel
Small Sample SizeDifficulty identifyingReading by Single
person
Colourful India all in one Plate!
Identification: Enterococcus
Identification: E. coli
Baseline
0 hours ( post- HWWS)
0.5 hrs
1 hour
1.5 hours
ConclusionRecontamination rate very quick
Within half an hourNot useful for evaluating handwashing
campaignsBut indicates environmental exposure?
Routes of TransmissionSub-study:
Enterococcus: Food Preparation, Child rearing E.coli: Food preparation, Contact with animals,
agricultural produce/crops
Further Research
AcknowledgementsWolf Peter Schmidt – LSHTMVal Curtis and Adam Biran – LSHTMBob Aunger – LSHTMDivya Rajaraman, Kiruba Sankar, John
Kenneth St. John’s Research Institute)Mary Matthews – Christian Medical College,
Vellore
Thank you