A simulated
outbreak – case
Scenarios
Abdullatif Sami Al Rashed
Clinical Microbiology Resident
King Fahd Hospital of The University

Outlines
• Introduction
• Simulated outbreak cases
• Steps of outbreak invesitgations.

Introduction
Investigations of acute infectious disease outbreaks are very common in hospital
settings.
The most important reason to investigate a recognized outbreak of disease is
that exposure to the source of infection may be continuing; so by identifying
and eliminating the source of infection, we can prevent additional cases.
Other reasons for investigating outbreaks are the opportunity to 1) describe new
diseases and learn more about known diseases; 2) evaluate existing prevention
strategies, e.g., vaccines; 3) teach (and learn) epidemiology; and 4) address
public concern about the outbreak.
Association for Professionals in Infection Control (APIC) and Epidemiology, Inc. (2014). Chapter 12: Outbreak Investigations. In APIC Text of
infection control and epidemiology (4th ed.).

Definitions
Association for Professionals in Infection Control (APIC) and Epidemiology, Inc. (2014). Chapter 12: Outbreak Investigations. In APIC Text of
infection control and epidemiology (4th ed.).
Term Definition
An outbreak An increase in the incidence of a particular infection or colonization over the
expected rate or when an unusual microbe or adverse event is recognized.
Pseudo-
outbreak
Episode of increased disease incidence due to enhanced surveillance or
other factor not related to the disease under study. (There is a rise in test
results without actual clinical disease)
Cluster An aggregation of cases in a given area over a particular period regardless of
whether the number of cases is more than expected.

Definitions
Association for Professionals in Infection Control (APIC) and Epidemiology, Inc. (2014). Chapter 12: Outbreak Investigations. In APIC Text of
infection control and epidemiology (4th ed.).
Term Definition
Epidemic
curve
is a graph in which the cases of a disease that occurred during an outbreak
are plotted according to the time of onset of illness in each case.
Case
definition
is a standard set of criteria for deciding whether an individual should be
classified as having the health condition of interest. A case definition
includes clinical criteria and, particularly in the setting of an outbreak
investigation, restrictions by time, place, and person.
Line-listing is a two-column list with variables in one column and the number and
percentage of those who match that variable in the other column.

What are the ways to
recognize an outbreak?
• Routine surveillance activities
• Reports from clinicians and
laboratories
• Reports from affected
individuals.
Chapter 12: Outbreak Investigations. In APIC Text of infection control and epidemiology (4th ed.).

Role of Microbiology lab In
Outbreak Investigation
The microbiology laboratory plays a crucial role in providing
investigative support in an outbreak investigation and in the creation
of routine surveillance information. The availability of culture
reviews, which may result in the initiation of an outbreak
investigation.

Causes of Pseudo-outbreaks?
1- Laboratory factors
◆ Introduction of a new test which was previously
unavailable locally.
◆ Introduction of a new laboratory test with poor
specificity and/ or sensitivity.
◆ Improved laboratory techniques for identification.
◆ Contamination during processing in the laboratory of
media or cross- contamination of the specimen during
processing.

Causes of pseudo-outbreaks?
2- Ward level
◆ Mis-labelling of specimens. Remember, if in
doubt, ask for another specimen!
◆ Contamination during collection of
specimens if the correct procedure is not
followed or specimen sent in a non- sterile
container.
◆ Incorrect diagnosis of clinical entity.

Causes of pseudo-outbreaks?
3- Environmental factors
◆ Use of poor quality of water in the endoscopic washer disinfectors.
• This can occur due to the presence of environmental mycobacteria (e.g.
Mycobacterium chelonae) from the rinse water which subsequently contaminated
bronchial washings sent for culture, leading to false positive results.

Steps of an outbreak investigation
1.Verify the diagnosis.
2.Confirm the outbreak.
3.Define a case and conduct case
finding.
4.Tabulate and orient data.
5.Take immediate control
measures.
6. Formulate hypothesis.
7. Test your hypothesis.
8. Plan and execute additional
studies.
9. Implement and evaluate control
measures.
10. Communicate findings.
These steps may occur simultaneously or be repeated as
new information is received.
Third (3rd) edition of GCC Infection Prevention & Control Manual.

KFHU OUTBREAK CASES

Case 1
• Known case of SCD admitted to 4C with Vaso-
occlusive crisis, Date of Admission (DOA)
10/6/2019.
• Shifted to MICU in 19/6/2019 duo to cardiac
arrest , bed E137-A
• Was having multiple bed sores, Folyes catheter
and Jagular CV line and on mechanical ventilator
Rectal Screening on 4/7/2019 grew:

Case2
• Presented with Stroke. DOA 3/5/2019.
• Admitted in MICU Multiple time last one in
17/6/2019, bed E-144 A
• Was bed ridden and have stroke, dementia, on
mechanical ventilation developed VAP
Transtracheal Culture on 7/9/2019

Case 3
• K/C Chrons disease admitted with
acute flare attack with intestinal
obstruction. DOA 22/6/2019
• Admitted in MICU in 1/7/2019, duo to
ARDS and was intubated on
mechanical ventilation bed E-143 A
• Bed ridden and have stroke, dementia,
on mechanical ventilation developed
VAP
Transtracheal Culture and sacral bed sore swab on
11/7/19

Case 4
• DOA: 23/6/2019,
• Medically free presented with pylonephritis,
kidney stones, S/P stone removal. Developed
sepsis and VAP after the operation.
• intubated on mechanical ventilation shifted to
SICU in 26/6/19 bed A-101 A
Rectal screening on 4/7/2019

Case 5
• K/C DM, HTN, CAD, HF, Post bariatric
surgery. DOA: 3/6/2019.
• Admitted to SICU multiple times duo to
intra-abdominal collections last admission
on 6/7/19 bed A-104 G
• Intubated on mechanical ventilation.
Throat swab on 7/7/2019

Case 6
• DOA 4/7/2019,
• Presented with
decreased level of
consciousness duo to
subdural hematoma,
admitted to SICU on
4/7/2019 bed A-104 C .
• Intubated on mechanical
ventilation.
Throat swab on 7/7/2019

Case 7
• DOA 23/6/2019,
• Presented with
polytrauma duo to
RTA, was intubated
in 23/6/2019 on
mechanical
ventilation in SICU
bed A-104 F
Transtracheal aspirate on 7/7/2019

Summary of Cases
In a one-week interval (4-11/7/2019)
Nearly all of the cases are in near by beds
7 cases grew same strain of MDR Acinetobacter buamannii in surgical and medical ICUs
4 SICU 3 MICU

Cont
Microbiolgy oncall team
suspected possible outbreak duo
to recurrent isolation of same
strain of A.bummanii
Infection Control department
has been notified to start an
investigation of possible
outbreak

Before starting any investigation:
• Get a commitment of support from the hospital staff and an approval
from the administration and microbiology department.
• Designate a leader for the investigation.
• Advise microbiology to save specimens and isolates for antimicrobial
susceptibility testing , molecular and non-molecular typing .
• Alert laboratory to keep any subsequent isolates that may be part of
the outbreak.

1- Verify diagnosis of the reported cases;
identify agent if possible
1. Rule out pseudo-outbreak
2. Characterize the nature of disease and signs and symptoms by
reviewing patient charts.
3. Obtain appropriate laboratory specimens to identify specific agent
responsible.
In Our Cases?

2- Confirm the existence of an outbreak
• Compare the current incidence with the usual or baseline
incidence:
• Make initial judgment using numerator data.
• Do this comparing the outbreak period rate with the background
rate of the same disease.
• If no local data is available use outbreak rates from the literature.

5
Comments and Recommendations:
Graph Represents the 1st and 2nd quarter of 2019 monthly data over time for “Hospital
acquired MRAB rate”. The P values are less than (0.05), therefore the process was unstable.
and was present of special cause Version.
Graph Represents the comparison of the actual performance of Hospital acquired MRAB
rate of 2014 to the 2nd quarter of 2019 by quarters with the Benchmark. There is an increase
in the rate during the 2nd quarter 2019 (MRAB outbreak in MICU during the month of April
and MRAB outbreak in CCU during the month of May-June)both outbreak were investigated
and corrected by infection control team ),main reasons for the outbreak are 1- the non
availability of recommended supply for cleaning and disinfection of medical equipment
2- staff are not fully compliant with cleaning and disinfection of medical equipment
Letters was made with recommendations to concerned department and administration
Hospital Acquired MRAB rate per 1000 patients days
Infection ControlResponsibility
ProcessType
High risk, Problem prone.Criteria for selection
number of new cases of hospital acquired MRABNumerator
number of patients daysDenominator
N/D * 1000Equation
≤1.2%Threshold
Patient chart/records, Quadra med CPR System, Lab resultData source
SafetyDimension of Performance:
MonthlyFrequency of measurement
1
2
2
1
KFHU Data

3-Define a case definition and conduct case
finding
• Develop a specific case definition using:
Symptoms or laboratory results (Person)
Time period (Time)
Location (Place)
• Conduct surveillance using case definition
Existing surveillance
Active surveillance (e.g. review medical records)
• Interview case-patients
Must be applied consistently and without
bias to all persons under investigation
The case definition maybe changed as new
information is gathered.

Characterize cases of diseases by person,
place and time
• Time: used to create an epidemic curve.
• Epidemic curve - Illustrates time course of the outbreak by drawing a histogram of
number of cases by their date of onset.
• Place:
• by service, ward, operating room. May use tables.
• Person:
• Characteristics of the case patients help in defining the most likely risk factors for
infection. Factors to assess include :
• Patient characteristics (i.e., age, sex, underlying disease)
• Possible exposures (i.e., surgery, nursing and medical staff, infected patients)
• Therapeutic modalities (i.e., invasive procedures, medications, antibiotics)
• Use all of the above to develop an accurate description of the population at risk

Reference: CBAHI outbreak management manual

3- Define a case and conduct case finding
• Classification:
• Definite (confirmed)
• Laboratory confirmed
• Probable
• Typical clinical features without lab confirmation
• Possible (suspected)
• Fewer of the typical clinical features

In our Cases?
• Person?
• Patients with multiple comorbidities have MDR Acinetobacter baumannii
• Place?
• MICU & SICU (specify the beds?)
• Time?
• July 2019

Search for additional cases:
• Encourage immediate reporting of new cases
by laboratory, physicians, nursing staff and
others as appropriate (e.g. radiology in new
cases of pneumonia).
• Search for other cases that may have
occurred retrospectively or concurrently
through laboratory reports, medical records,
patient charts, physicians and nursing staff
and public health data.

4-Tabulate and orient data
• Create line
listing with
benchmar
k
5
Comments and Recommendations:
Graph Represents the 1st and 2nd quarter of 2019 monthly data over time for “Hospital
acquired MRAB rate”. The P values are less than (0.05), therefore the process was unstable.
and was present of special cause Version.
Graph Represents the comparison of the actual performance of Hospital acquired MRAB
rate of 2014 to the 2nd quarter of 2019 by quarters with the Benchmark. There is an increase
in the rate during the 2nd quarter 2019 (MRAB outbreak in MICU during the month of April
and MRAB outbreak in CCU during the month of May-June)both outbreak were investigated
and corrected by infection control team ),main reasons for the outbreak are 1- the non
availability of recommended supply for cleaning and disinfection of medical equipment
2- staff are not fully compliant with cleaning and disinfection of medical equipment
Letters was made with recommendations to concerned department and administration
Hospital Acquired MRAB rate per 1000 patients days
Infection ControlResponsibility
ProcessType
High risk, Problem prone.Criteria for selection
number of new cases of hospital acquired MRABNumerator
number of patients daysDenominator
N/D * 1000Equation
≤1.2%Threshold
Patient chart/records, Quadra med CPR System, Lab resultData source
SafetyDimension of Performance:
MonthlyFrequency of measurement
1
2
2
1

5-Take immediate control measures
• If an obvious source of the contamination is identified…institute
control measures immediately!
• e.g.: Hand hygiene
• Additional use of barriers (e.g., gloves and gown),or specified
suspected product (e.g., patient care item)

In our cases
• Infection control department encourge for strict compliance to hand
hyagine, PPE use and isolation precautions.
What are the infection control precaution of A.baumannii ?

6-Formulate hypothesis
• Record, tabulate and review data collected from above activities to
summarize common host factors and exposures.
• Also Literature reviews of previous outbreaks.
• Develop a hypothesis (best guess) on the likely reservoir source, and
mode of transmission of the disease.
• Hypothesis should explain the majority of cases

Hypotheses should address
• Reservoir
• Source of the agent
• Mode of transmission (Vector or vehicle )
• Exposure that caused disease
Review data to determine common host factors and exposures.

7- Test hypothesis
• Analyze data derived from case investigation and determine sources
of transmission and risk factors associated with disease.

TEST HYPOTHESIS
ELGUJJA

What is your hypothesis in our
cases?

8-Plan and execute additional studies
• Environmental sampling or personnel based
oCollect appropriate samples
oAllow epidemiological data to guide testing
oIf analytic study results are conclusive, don’t wait for positive samples
before implementing prevention.

In our cases
Investigation was done by the IC team to determine the
source of this recurrent outbreak through direct observation
and environmental cultres.
Including ECG Machines, Nurse stations tables, Portable CXR,
Stethscopes, portable computers, Infusion pumps, bedside files table,
PPE tables, E.g.

IC
• Envornmental cultures showed growth of Acintobacter baumannii
MDR (same strain isolated from the patients) in SICU ECG machine.
• Which after investigations showed that is the shared by SICU, MICU, 1D,
burn unit and other units.
• The source of this oubreak has been identified.
• Furthermore, Pseudomonas aerigonosa, Pantoea spp, and E.coli have
beem identified from other medical equepiments.

9-Implement and evaluate control measures
1. Prevent further exposure and future outbreaks by eliminating or
treating the source
2. Work with regulators, industry, and health educators to institute
measures
3. Create mechanism to evaluate both short-and long-term success.

In our Cases
• In order to prevent recurrent outbreaks, these actions have
been applied:
Guiding all units about proper cleaning & disinfiction of
medical equipment after each use by the concerned staff
(user).
Strict compliance to hand hyagine, PPE use and isolation
precautions.
KFHU MRAB IPP

10-Communicate findings
Oral
briefing.
Written
report.
Summarize investigation, make
recommendations, and disseminate
report to all participants.

References
• Third (3rd) edition of GCC Infection Prevention & Control Manual.
• Association for Professionals in Infection Control (APIC) and Epidemiology, Inc.
(2014).
• Chapter 12: Outbreak Investigations. In APIC Text of infection control and
epidemiology (4th ed.).
• KFHU outbreak management IPP
• CBAHI Outbreak Management Manual

Thank you