Bacterial recontamination of hands following handwashing in India - Carol Devamani, LSHTM alumna

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