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Development of Outbreak
Investigation Database for
hospital Infections
Osaka University,
Faculty of Medicine, JAPAN
Kiyoko Makimoto, Ph.D., MPH
What are hospital infections?
• Two types of infections you
find in the hospital
– Hospital-acquired infections
– Community-acquired infections
• How can we distinguish them?
– By latency period
– CDC definition for NIs:
development of infections after
48 hours of admission
Brief history of hospital infections
• First well documented hospital infections
– In the middle of 1800 Lying-in Hospital in Vienna
– Maternal mortality rates exceeded 10%, mainly
due to puerperal fever (child-bed fever) endemic
• Modern epidemiology of hospital infections
– In 1950s, Staphylococcus aureus infection
outbreaks in hospitals all over the world
• Advances in 1970
• Intensive research in the 1990s
What kinds of hospital
infections exit?
• Device-related
– Blood stream infections (BSI)
– Urinary tract infections (UTI)
– Ventilator-associated pneumonia (VAP)
• Procedure-related
– Surgical site infections (SSI)
• Environmental contamination
– Water, disinfectant, etc.
Devices and procedures as major
sources of hospital infections
Changes in flora due to
antibiotic therapy :20-25%
Others:
20%
Respirators
Cross-infections:
20-40%
Surgeries
Arterial/venous
catheters
Patients’
own flora:
40-60%
Urinary
catheters
Why do we need to study
hospital infections?
•
•
•
•
Not all hospital infections are
preventable, but they are associated
with
Excess length of hospital stay
Excess cost
Excess mortality
Law suits
Distribution of hospital infections
by sites, SENIC study
Urinary tract
Surgical wound
Pneumonia
Bacteremia
Other sites
Increases in the mean length of hospital
stay due to hospital infections
in the U.S. , SENIC study
Bacteremia
Surgical wound
Pneumonia
Urinary tract
Other sites
All
0
1
2
3
4
Days
5
6
7
8
Excess cost of hospitalization due to
hospital infections in the U.S., 1992
Pneumonia
Bacteremia
Surgical wound
Urinary tract
Other sites
All
0
1000
2000
3000
U.S. dollars
4000
5000
6000
Who are at risk for acquiring
hospital infections?
• Patients in Intensive Care Units
– ICU （medical, surgical, burn, Neonatal ICU、
Pediatric ICU)
– Surgery department
• Immunocompromised patients
– Cancer treatment, transplant, HIV infections
• Other factors
– Age, smoking, chronic diseases
Distribution of hospital infections
by infection sites and
endemic/outbreak status
Urinary tract
Surgical wound
Pneumomia
Hepatitis
Gastroenteritis
Cutaneous
Bacteremia
Other
Endemic
Outbreak
Why do we need an outbreak
investigation database?
• Literature search is considered essential
for outbreak investigation
• Difficulty in collecting relevant articles in
hospitals with limited resources
• Shortage of health care workers trained in
epidemiology in Japan
• Epidemiology of hospital infections is not
taught in school
Conducting Medline search
• Medline search yielded >600 articles
between 1970 and 2000
• Only a small number of outbreak
investigations reported all the information
necessary to replicate the investigation
• Recent investigations tend to focus on
DNA typing to identify epidemic strains
What kinds of outbreaks have
been reported?
• The largest number of people affected
– Norwalk-like virus affected 635 employees
(27% attack rate), 79 people affected in a single
day
– Am J Epidemiol. 1988 Jun;127(6):1261-71.
• The longest duration
– >= 10 years of unrecognized hospital
transmission of legionnaires' disease among
transplant patients (25 cases)
– Infect-Control-Hosp-Epidemiol. 1998 Dec;
898-904
19(12):
Continued
• Unusual source of outbreak
– Klebsiella pneumoniae producing ESBL
transmitted by gel used for ultrasonography
– 2 adults and 1 neonates were infected; 5
colonized
– J-Clin-Microbiol. 1998 May; 36(5): 1357-60
• Outbreak due to non-infectious origin
– Hemolysis (discolored, pink serum
visualized in spun serum sample) due to
defect products (30 cases in 11 days)
– Kidney-Int. 2000 Apr; 57(4): 1668-74
What kinds of fields do we need?
•
•
•
•
Mode of transmission
Pathogens
Type of investigation
Place (NICU, ICU,
surgery, etc.)
• Country
• Author
•
•
•
•
Hospital size
No. of patient affected
No. of deaths
Detail investigation
process
• Infection control and
prevention strategies
Usefulness of the Database I
• A learning tool for epidemiologic and
microbiologic investigations
– Specific pathogens to look for in certain
symptoms
– Guide epidemiologic investigations
• Identify study design in similar situations
• Types of information to collect
Epidemiologic skills required in
complex investigations
• Case definition
– Able to learn how to write a case
definition to find cases
• Selection of controls in case-control
studies
– Selection of controls is the most difficult
part
Usefulness of the Database II
• Provide infection prevention strategies
by
– pathogens
– type of service
– infectious diseases
– mode of transmission, etc.
Searching by
Pathogens:
Acinetobacter
baumannii
Any impacts of the database on
Japanese culture?
• Very few Japanese professionals report
outbreak investigations
• Reporting outbreaks to professional
journals as professional and social
obligation
• Providing information in sufficient detail to
help investigations
Challenges
• Currently 220 records have been entered
• Changes in hospital practices affecting
the outbreak investigation
• Funding is necessary to complete and
keep updating outbreak database
Changes in hospital practices
• Factors related to patients
– Shorter hospital stay
– Increased patients’ acuity
– Increases in intra- and inter-hospital transfer
• Factors related to health care workers
– High turnover of nurses
– Floating shift
– Employment of temporary staff
Your comments are greatly
appreciate it
URL for the outbreak investigation database
http://health-db.net/infection/index.asp