Surveillance of
antimicrobial resistance
Liselotte Högberg
Swedish Institute for Infectious
Disease Control
E-mail: liselotte.hogberg@smi.ki.se
OVERVIEW
Basic principles
Why, what, how and who?
Antimicrobial surveillance in Sweden
Different types of surveillance
Validity of surveillance data
Sensitivity, specificity
Basic principles
WHY?
- Defining/updating treatment guidelines
- Identifying needs for infection control
measures
- Monitoring the impact of interventions
to improve antimicrobial use and control
spread of infection
Basic principles
WHAT?
• Should be focused on pathogens of
greatest public health importance
• Should include pathogens that are
readily transmissible
• Should provide information for action
at local and national levels
Basic principles
HOW ?
• Comprehensive surveillance
• Sentinel surveillance
• Point-prevalence studies
Basic principles
Comprehensive surveillance
- Includes the whole population at
risk
- Aiming to capture all cases
- Involves large number of clinicians
and laboratories – only limited set of
data
Basic principles
Sentinel surveillance
- Indicator data for rest of population
- Suitable when prolonged and detailed
data is required
- Target approach (instead of
representative sample) might be suitable
Basic principles
Point prevalence studies
- Useful for validation of
representativity of surveillance data
- Evaluation of interventions
Basic principles
WHO ?
• General population vs. hospital
in-patients
• Clinical reports
• Laboratory reports
Basic principles
DATA SOURCE
Clinical data
Laboratory data
+ timely information on
clinical disease
+ objective confirmation of
the diagnosis
+ possibility to get
detailed patient
information
+ opportunity for detailed
characterisation of the
causative organism
- dependent on accuracy
and consistency in
diagnosis and timely and
complete reporting
- less timely
- often few clinical details
Basic principles
Numerators for surveillance
• Data should relate to a single episode of
illness in a patient
• Microbiological data: only the first positive
culture from the patient from each disease
episode should be reported
• Microbiological data: qualitative or
quantitative
Basic principles
Examples of antimicrobial
surveillance projects
ANNUAL REPORTS
DANMAP – Denmark
FIRE – Finland
NORM – Norway
SWEDRES – Sweden
EARSS (www.earss.rivm.nl)
RESEARCH/INDUSTRY INITATIVES
Alexander project
Sentry
Basic principles
Examples of antimicrobial
surveillance systems
ANNUAL REPORTS
DANMAP – Denmark
FIRE – Finland
NORM – Norway
SWEDRES – Sweden
EARSS (www.earss.rivm.nl)
RESEARCH/INDUSTRY INTITATIVES
Alexander project
Sentry
AMR surveillance in Sweden
Antimicrobial resistance
surveillance in Sweden
1. Mandatory case notification
2. Annual resistance surveillance and
quality control programme (RSQC)
3. Sentinel surveillance
4. EARSS
AMR surveillance in Sweden
Antimicrobial resistance surveillance in Sweden
Mandatory case notification
Comprehensive surveillance of all cases of MRSA,
VRE and penicillin-resistant pneumococci (PRP) to
the Swedish Institute for Infectious Disease Control
Mandatory for both the clinician having seen the
patient and the laboratory diagnosing the pathogen
Basic patient data: age, sex, place of residence
Data presented as incidence figures (population
denominator)
AMR surveillance in Sweden
Antimicrobial resistance surveillance in Sweden
Annual resistance surveillance and
quality control programme (RSQC)
Each laboratory report resistance data for at least
100 consecutive bacteria per year
Includes S. pneumoniae, S. aureus, E. coli,
S. pyogenes, H. pylori, E. faecalis/faecium
No patient data avilable
Detailed resistance data
Data presented as proportion (% resistant isolates/
all isolates)
AMR surveillance in Sweden
Antimicrobial resistance surveillance in Sweden
Sentinel surveillance
Data mainly derived from special investigations by
devoted laboratories
At present includes salmonella, shigella,
campylobacter, N. gonorrhoeae, N. meningitidis
Quality of data varies
AMR surveillance in Sweden
Antimicrobial resistance surveillance in Sweden
EARSS
Funded by DG SANCO of the European
Commission
Surveillance of antmicrobial susceptibility of
invasive infections of S. aureus, S. pneumoniea,
E. coli, E. faecalis/faecium
27 countries participates
www.earss.rivm.nl
EARSS:
Proportion PRP isolates in year 2000
AMR surveillance in Sweden
INFORMATION FEEDBACK
ResNet
(www.srga.org/resnet_sok.htm)
Electronic database containing data from
RSQC, EARSS and sentinel surveillance
SwedRes
(www.smittskyddsinstitutet.se)
Annual report on Swedish antibiotic
utilisation and resistance in human and
veterinary medicine
Data validity
PRP
(penicillin-resistant pneumococci)
Streptococcus pneumoniae MIC PcG >= 0,5 mg/L
Notifiable in Sweden since 1996
Increasing resistance problem internationally
Surveillance data available from mandatory data, RSQC
and EARSS
Data validity
7
6
5
4
3
2
1
0
1997
1998
1999
2000
2001
2002
2003
Year
Incidence/ 100 000 inh (PRP MIC PcG >= 0,5 mg/L)
Data validity
7
6
5
4
3
2
1
0
1997
1998
1999
2000
2001
2002
2003
Year
Incidence/ 100 000 inh (PRP MIC PcG >= 0,5 mg/L)
RSQC rate (PRP MIC >= 0,12 mg/L)
Data validity
7
6
5
4
3
2
1
0
1997
1998
1999
2000
2001
2002
2003
Year
Incidence/ 100 000 inh (PRP MIC PcG >= 0,5 mg/L)
RSQC rate (PRP MIC >= 0,12 mg/L)
EARSS rate (Invasive PRP >= 0,12 mg/L)
Data validity
7
6
5
4
3
2
1
0
1997
1998
1999
2000
2001
2002
2003
Year
Incidence/ 100 000 inh (PRP MIC PcG >= 0,5 mg/L)
RSQC rate (PRP MIC >= 0,12 mg/L)
EARSS rate (Invasive PRP >= 0,12 mg/L)
PRP rate (PRP MIC PcG >= 0,5 mg/L)
Data validity
NPH cultures / 1000
inhabitants
25
20
15
10
5
0
1998
1999
2000
2001
2002
2003
Year
Nasopharyngeal cultures/1000 inhabitants in Sweden
1998-2003
Data validity
Changes in culturing propensity
80000
Nasopharyngeal cultures
70000
60000
50000
40000
30000
20000
10000
0
0
2000
4000
6000
S. pneumoniae
8000
10000
12000
Data validity
Ideal surveillance data
• Maximum specificity
– Limit false positives
• Maximum sensitivity
– Captures all true positives
– Determination of break-points at laboratories
– Transient nasal carriage (MRSA)
Data validity
Specificity
• Methodological problems at the
laboratory
• Reporting bias from laboratories
Data validity
Determinants for sensitivity
1. Contact with health care services
2. The pathogen is isolated
3. The case is reported
There is a risk for bias in each step!
Data validity
Contact with
health care services
• Accessibility
– Better access to physicians in large cities
• Costs
– Free health care for children, cost recovery
systems
• Socio - economy, tradition
• Screening/contact tracing initiatives
Routines for
contact tracing
for PRP
MIC PcG > 0,5 mg/L
Multi-resistance or
high MIC-values
Individual
Data validity
Isolation of the pathogen
• Cultures from all cases/only on
therapeutic failures?
• Tradition in culturing propensity
• Economical obstacles
• Fear of time-consuming contact tracing
Data validity
Nasopharyngeal culturing propensity in Sweden 1998-2002
(Number of nasopharyngeal cultures/1000 inhabitants)
Data validity
Who is sampled?
Treatment failure
Disease Carriage
Antibiotic
treatment
PRP incidence / 100 000 inh
Data validity
40
35
G
M
30
25
20
15
10
5
0
1998
1999
2000
2001
Year
PRP incidence/1000 inhabitants
(all cases) in area G and M
2002
PRP incidence / 100 000 inh
Data validity
6
G
M
5
4
3
2
1
0
1998
1999
2000
2001
2002
Year
PRP incidence (only index cases)
in area G and M
Summary
Summary: Basic principles
• Obtaining appropriate specimens from
the infected individual
• Successful isolation of the causative
organisms
• Accurate determination of antimicrobial
resistance
• Data collection, collation and analysis
• Dissemination of appropriate information
for action