Outbreak Investigation of Healthcare Associated Infections
1. Outbreak Investigation
of Healthcare-associated Infections
Ma. Liza Antoinette M. Gonzales, MD, MSc, FPPS,
Associate Professor, Department of Pediatrics
University of the Philippines Manila
2. Objectives of this session
• Define what is meant by an outbreak
• Discuss the steps of an outbreak
investigation in the hospital
• Apply the steps in a hypothetical
case of an outbreak
3. Healthcare-associated
Infections (HAI)
• Also referred to as “nosocomial” or “hospital-
acquired” infection, is defined as:
• An infection occurring in a patient during the
process of care in a health-care facility which
was not present or incubating at the time of
admission.
• Usually occur at 48 hours or more after
admission
• Includes infections acquired in the hospital but
appearing after discharge and occupational
infections among staff.
5. Risk Factors for HAI
• Prolonged use of invasive devices
• Inappropriate use of antibiotics
• High-risk and sophisticated procedures
• Immuno-suppression
• Severe underlying patient conditions
• Admission to the ICU
• Insufficient application of standard and
isolation precautions
• Inadequate infection control and
prevention measures
WHO, Infection Control. http://www.who.int/csr/bioriskreduction/infection_control/en/index.html
6. Risk Factors in settings with
limited resources:
• Inadequate
environmental hygienic
conditions and waste
disposal
• Poor infrastructure
• Insufficient equipment
• Understaffing
• Overcrowding
• Lack of procedure
• Poor knowledge and
application of basic
infection control
measures
• Lack of knowledge of
injection and blood
transfusion safety
• Absence of local and
national guidelines and
policies
WHO, Infection Control. http://www.who.int/csr/bioriskreduction/infection_control/en/index.html
7. Common Healthcare-associated
infections
• Blood-stream infection
• Central line-associated bloodstream
infections
• Hospital acquired / Ventilator-
associated pneumonia
• Catheter-associated urinary tract
infections
• Surgical site infections
8. What is an Outbreak?
• An Outbreak is defined as an increase in
occurrence of cases (HAI) above what is
expected in that population in that area
over a particular period of time
• Important to consider or establish
background rate
• One case of a rare occurrence or many
episodes of a common occurrence can be
an outbreak
CDC. Principles of Epidemiology in Public Health Practice . 3rd ed. Updated 2012
9. Epidemics and Clusters
• Epidemic - same as outbreak but used for
a wider geographic area
• Cluster - aggregation of cases in a given
area over a particular period without
regard to whether the number of cases is
more than expected; some are true
outbreaks, some are sporadic and
unrelated cases of the same or unrelated
disease
CDC. Principles of Epidemiology in Public Health Practice . 3rd ed. Updated 2012
10. Exercise 1
• Which of the following situations can be
an outbreak?
A. Two adult patients with COPD develop
pneumonia after admission to the general
medical wards
B. One patient in the surgical ward develops
purulent discharge on the surgical incision
site
C. 10 postpartum women develop abdominal
wound dehiscence after cesarean section
within 2 weeks
D. Two cases of varicella in the pediatric ICU
within 5 days
✔
✔
11. Reasons for Investigating
Outbreaks
• Identify the source and control
further transmission
• Develop strategies to prevent future
outbreaks
• Evaluate existing prevention
strategies
• Describe new diseases and learn
more about known diseases
• Address public concern
Reingold AL. Emerging Infectious Diseases 1998; 4 (1): 21-7.
12. Investigating an Outbreak
WHO, Infection Control. http://www.who.int/csr/bioriskreduction/infection_control/en/index.html
Systematic planning and
implementation of an outbreak
investigation is necessary
13. Outbreak Investigations:
The 10-Step Approach
1. Identify investigation team and resources
2. Establish existence of an outbreak
3. Verify the diagnosis
4. Construct case definition
5. Find cases systematically and develop line listing
6. Perform descriptive epidemiology/develop
hypotheses
7. Evaluate hypotheses/perform additional studies as
necessary
8. Implement control measures
9. Communicate findings
10. Maintain surveillance
14. 1. Identify the Investigation team
and resources
• Once an outbreak is suspected, notify
appropriate individuals and departments in the
institution (Chief of the affected service, head
nurse of the unit, hospital administration)
• Establish an Outbreak Investigation Team with
clear delineation of responsibilities
• Cooperation of various healthcare professionals
is essential for efficient investigation and
implementation of control measures
• Identify available resources: personnel,
supplies, laboratory
15. Who should be part of the
Outbreak Investigation Team?
• Infection control staff must be part
of the outbreak team.
• Other members:
– Local – Hospital Epi teams,
microbiologist, other trained medical or
clinical personnel
– National - Disease Investigation
Specialists; DOH-Epidemiology Bureau
– Others – WHO, Philippine FDA
16. 2. Confirmation of Outbreak
• Confirm whether there is an
outbreak by reviewing the following:
– preliminary information on the number
of potential cases
– available microbiology
– severity of the problem
– demographic data of cases
– place and time
• Review definition of OUTBREAK
17. 3. Verify the Diagnosis
• Review existing data
– Medical records/charts
– Surveillance records
– Microbiology
– Other Laboratory reports and records
• Interview unit medical/clinical personnel
and paramedical staff
• Clinical observations
• Contact Hospital Epidemiologist &
Infection Control team
• Conduct clinical testing if needed
18. 4. Construct Case Definition
• Case definition is a set of standard criteria for
classifying whether a person has a particular
disease, syndrome, or other health condition.
• Decide what constitutes a case, what you are
looking for
• Narrow enough to focus efforts but broad
enough to catch all the cases
• Define 3 essential characteristics of disease:
Person, Place, Time
• A gradient of definition based on level of
evidence (as suspected, probable, or
definite/confirmed case) is often helpful
19. Case Definition
• Use previously published, validated
definitions if available and applicable
– e.g. CDC/NHSN Surveillance Definitions for
Specific Types of Infections 2017
• Where not available, use standardized
written case definitions to ensure precise
surveillance.
• Use the same definitions for accurate and
valid comparisons of data over time and
across institutions
20. CDC/NHSN 2017 Surveillance Definitions
for Specific Types of Infections
• Primary bloodstream infections (BSI): Laboratory-
confirmed bloodstream infections (LCBI) that are not
secondary to an infection at another body site
• Central line-associated BSI (CLABSI): A
laboratory-confirmed bloodstream infection (LCBI)
where central line (CL) or umbilical catheter (UC)
was in place for >2 calendar days on the date of
event, with day of device placement being Day 1,
AND the line was also in place on the date of event
or the day before.
21. CDC/NHSN 2017 Surveillance Definitions for
Specific Types of Infections
• Pneumonia (PNEU) - identified by using a
combination of imaging (new or progressing
abnormalities on chest imaging test), clinical(e.g.
New onset or worsening purulent sputum or cough,
or dyspnea or tachypnea and laboratory criteria
(culture of blood/respiratory specimens or
histopathologic test).
• Ventilator-associated pneumonia (VAP): A
pneumonia where the patient is on mechanical
ventilation for >2 calendar days on the date of event,
with day of ventilator placement being Day 1, AND
the ventilator was in place on the date of event or
the day before.
22. CDC/NHSN 2017 Surveillance Definitions for
Specific Types of Infections
• Non-Catheter-associated Urinary Tract Infection
(Non-CAUTI) - Patient has at least one of the ff:
fever, suprapubic tenderness, costovertebral angle
pain or tenderness, urinary frequency, urinary
urgency, dysuria AND has a urine culture with no
more than two species of organisms identified, one
of which is a bacterium of ≥105 CFU/ml.
• Catheter-associated UTI (CAUTI): A UTI where an
indwelling urinary catheter was in place for >2 days
or the day before AND patient has clinical signs and
symptoms of UTI AND has a urine culture with no
more than two species of organisms identified, one
of which is a bacterium of ≥105 CFU/ml.
23. Sample Case Definition: Outbreak of
Hospital-acquired Pneumonia
Person
Place
Time
Components of
Case Definition
Hospital-acquired Pneumonia
• Occurring after admission to
ward A
• During May-August 2016
• New/progressing abnormalities on
chest imaging test AND new onset or
worsening purulent sputum/cough, or
dyspnea or tachypnea AND positive
culture of blood or resp. specimens
24. 5. Find cases systematically
and develop line listing
• How do you find cases?
– Microbiology data
– Infection control or surveillance records
– Discussions with clinicians
– Pharmacy records
– Medical records
– Nursing charts
– Pathology reports
25. Develop Line Lists
• Line list - used to summarize information
• What to put on a Line List
– Demographic information (age, sex,
occupation, hospital numbr, date of
admission, date of surgery, etc)
– Clinical Data: Signs and Symptoms, Onset
dates and/or times, Outcomes, Lab results,
Antimicrobials, other Medications
– Exposure information : procedures or
surgery; medical devices or equipment
– Other potentially relevant data
27. • Don’t get bogged down with case
definitions and capturing all cases
• Goal of Outbreak investigation is
NOT to find and describe every case
• Goal is to STOP THE OUTBREAK –
do not need to find every case
28. 6. Perform Descriptive epidemiology
and develop hypotheses
• Examine the distribution of a disease in a
specific or defined population (“at-risk
population”)
• Describe the basic features of its
distribution in terms of Person, Place,
Time
• Assess Time-trend: Point source,
propagated or circulating, recurrent or
cyclical, seasonal, combination
• Conduct surveillance
29. Surveillance
• Defined as: “The ongoing, systematic
collection, analysis, interpretation, and
dissemination of data regarding a health-
related event for use in public health
action to reduce morbidity and mortality
and to improve health.’’
• Basic components of a surveillance
system:
– Data collection
– Procedure for evaluating data and making
comparisons
– A means for disseminating the results
Centers for Disease Control and Prevention. Updated guidelines for evaluating public health surveillance systems:
recommendations from the guidelines working group. MMWR 2001;50:1-35.
30. Retrospective Surveillance
• Retrospective surveillance
– Comprehensive review of sequential
events in the medical records and
examination of information even after
patient is discharged
– Avoids time-consuming efforts of
locating and reviewing charts
– Disadvantage: does not permit
interactions with ongoing caregivers or
verifying data collected
31. Active Surveillance
• Prevalence study (Cross-sectional study)
– Identify all patients with HAI hospitalized at a
given point time in the entire hospital, or on
selected units.
– Useful for conducting initial assessment of
current issues, before proceeding to a more
focused continuing active surveillance
programme.
– Outcome measure is a Prevalence Rate.
32. Active Surveillance
• Incidence study (Prospective, longitudinal)
– Detect new cases during the surveillance period
– Preferable if data can be collected regularly and patient
is still under the care of the institution
– Able to capture information in real time, interview
patient’s caregivers, interactively obtain or observe
findings that may not be recorded in the patient record
– More effective in detecting differences in infection
rates, to follow trends, to link infections to risk factors,
and for inter-hospital and inter-unit comparisons
– Outcome measure are Incidence rates, Attack rates,
and Infection ratio
33. Prevalence Study (Cross-sectional study)
Patient A
Patient B
Patient C
Patient D
Patient E
Patient F
Patient G
Patient H
Point Prevalence- assess
only HAIs active on the day
of the survey
7 days
Period Prevalence- include HAIs active on
the day of the survey and those active during
a predefined period before the survey day
34. Exercise: Compute HAI Prevalence rate
Patient A
Patient B
Patient C
Patient D
Patient E
Patient F
Patient G
Patient H
7 days
Point Prevalence
2/8
(25%
)
Period Prevalence 5/8
(62.5%)
36. Epidemic Curves
• Graph used to depict the time
course of an outbreak or epidemic
• Provides a simple visual display of
the outbreak's magnitude and time
trend
• Graphs the number of cases by date
or time of onset of illness.
• Suggests type of exposure or time
of exposure
37. Time of Exposure is Possible if
Agent is known
Zack Moore, MD, MPH, Medical Epidemiologist. North Carolina Division of Public Health
38. Zack Moore, MD, MPH, Medical Epidemiologist. North Carolina Division of Public Health
Possible Agent can be Identified if
Exposure Time is known
41. Environmental Sampling
• Vital part of investigation
• Should be done with (not instead of)
epidemiologic investigation
• Ideally, epidemiologic results guide sample
collection – should not be taken randomly
• Can support epidemiologic findings
• Positive or negative results can be misleading or
difficult to interpret (consider contamination)
• Understand limitations
Environmental and personnel culturing should NOT be
the first step in any outbreak investigation!
42. Calculation of HAI Rates
• The frequency of infection can be estimated by
prevalence and incidence rates
• Rates are obtained by dividing a numerator by a
denominator
• Numerator - event of interest which can be:
– number of infections
– number of infected patients observed
• Denominator - can be any of the following:
– Total population in which the event may occur (at-risk
population)
– Number of patient-days of risk
Ducel G et al. Prevention of hospital-acquired infections. A practical guide. WHO Geneva 2002.
43. Ways to Calculate HAI Rate
• Prevalence rate (%)
– Number of patients with HAI (total or specific
infection) at the time of study divided by
Total number of patients observed or exposed
at the same time X100
• Cumulative Incidence rate (Attack rate)
– Number of new infections acquired in a period
divided by Total number of patients observed
or exposed at the same time X100
Lee TB et al. . Recommended practices for surveillance: APIC,Inc.Am J Infect Control
2007;35:427-40; Ducel G et al. Prevention of hospital-acquired infections. A practical guide.
WHO Geneva 2002 .
44. Ways to Calculate HAI Rate
• Risk Adjusted Infection Rates – rates are
expressed in terms of specific exposures
rather than using an overall census
denominator.
– Incidence rate PER PATIENT-DAYS: number
of new HAI pooled throughout the month(s)
divided by the patient-days of stay x 1000
– Incidence rate PER DEVISE DAYS: number of
new HAI pooled throughout the month(s)
divided by the device-days x 1000 (e.g.
catheter days)
Lee TB et al. . Recommended practices for surveillance: APIC,Inc.Am J Infect Control
2007;35:427-40; Ducel G et al. Prevention of hospital-acquired infections. A practical guide.
WHO Geneva 2002 .
45. Exercises
Calculate the Surveillance rate for the following:
6.2
1. Nosocomial sepsis rate (Prevalence rate)
No. of At-risk patients in one
month (newly admitted
patients + patients carried
over from previous month)
No. of sepsis
cases
Prevalence Rate (%)
(no. of sepsis cases ÷ no.
at-risk patients)
242 15
1.6
2. Procedure-specific SSI rate (Incidence rate)
No. of cesarean section
operations in one month
Total No. of New
Skin/Soft tissue
infection
Incidence Rate (%)
(no. of new SSI ÷ no. of
cesarean sec performed)
122 2
46. Exercises
4. Ventilator-associated pneumonia rate (Incidence rate per
device days)
No. of ventilator
days in pediatric
ICU
No. of ventilator-
associated
pneumonias in
pediatric ICU
Rate per 1000
ventilator days (no. of
ventilator-associated
pneumonias ÷ no. of
ventilator days x 1000)
801 5
Calculate the Surveillance rate for the following:
6.2
3. Urinary tract Infection (Incidence rate per patient-days)
Total patients-days of stay
during specified time
period)
No. of
UTI cases
Rate per 1000 patient-
days (number of UTI ÷
total patient-days x
1000)
989 11 11.1
47. Hypothesis Formulation
• Formulate hypothesis to explain the
observed increase in incidence
• Look into associations
• Formulate a hypothesis on the type
of infection (exogenous,
endogenous)
• Tentatively identify the source and
route of infection
48. 7. Evaluate hypotheses and perform
additional studies as necessary
• Test hypothesis about the relationship of a
disease to a specific cause
• Determine Cause-effect relationship by
conducting an epidemiologic study that relates
the exposure of interest to the outcome of
interest
• Typical study designs: cohort, case-control,
experimental design
• Determine the appropriate approach to
surveillance depending on the issue being
surveyed and available resources
49. Analytical Epidemiologic
Studies
• Cohort Studies (prospective or
retrospective)
– Include everyone who could have been
exposed
– A cohort study is feasible only when the
population is well defined and can be followed
over a period of time.
• Case-Control Studies (retrospective)
– Compare exposures among ill persons (case-
patients) and non-ill persons (controls)
50. Sample Study: Cohort
Risk Ratio = Risk in exposed group/ Risk in
unexposed group
Calculation: [a/a+b) ÷ c/c+d]
Ex. (25/53) ÷ (2/28) = 0.47/0.07 = 6.7
Interpretation: Exposed persons were 6.7x more
likely to develop HAI than those unexposed
HAI Cases No HAI
(Control)
total
Exposure 25 (a) 28 (b) 53
No exposure 2 (c) 26 (d) 28
Total 27 54 81
51. Sample Study: Case-Control
Odds Ratio: (No. exposed cases x No.unexposed
controls) divided by (No. exposed controls x
No.unexposed cases)
Calculation: [ad/ bc]
Example: 25x26/28 x 2 = = 650/56 = 11.6
Interpretation : Persons exposed had 11.6 times the
odds of developing HAI than persons not exposed
HAI Cases No HAI
(Control)
total
Exposure 25 (a) 28 (b) 53
No exposure 2 (c) 26 (d) 28
Total 27 54 81
52. Analytic Studies
• Can be useful for supporting your
hypothesis if no obvious source
identified
• Not always necessary
• Time consuming and challenging
• Small number of cases limits power
53. 8. Implement control measures
• Implement control measures to control the
outbreak
• Can occur at any point during outbreak
• Isolation, cohorting, drug or product recall
• Balance between preventing further
disease and protecting credibility and
reputation of institution
• Should be guided by epidemiologic results
in conjunction with environmental
investigation
54. Break the Chain of Infection
… stop the spread of Infectious
diseases
55. Hepatitis C Outbreak in Nevada
Endoscopy Center, 2008
• Potentially exposed > 50,000 patients to Hepatitis C and
other infectious diseases; 8 acute hepatitis C cases linked
directly, 10 hepatitis C cases possibly linked
• Identified breaches contributed to transmission:
– Reuse of syringes for more than one patient
– Reuse of single use vials of propofol for multiple patients
– Poor hand hygiene practices
MMWR May 16, 2008 / 57(19);513-7
56. General Infection Control Practices
that Prevent Nosocomial Infections
• Hand hygiene
• Standard (universal) precautions
• Isolation precautions : contact, droplet, and
airborne spread
• Environmental cleaning and disinfection
• Disinfection and sterilization of medical devices
and patient care equipment
• Enhanced healthcare provider education and
training
• Cohorting patients or staff
• Maintain adequate staffing levels
Siegel JD, et al. HICPAC 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents
in Healthcare Settings, June 2007 ; Pittet D, et al Lancet Infect Dis 2006; 6:641.; Haley RW et al. Am J Epidemiol
1985; 121:182.; Whitehouse JD et al.. Compr Ther 1998; 24:71.
57. Sample Control measures
for Outbreak Management
Ducel G et al. Prevention of hospital-acquired infections. A practical guide. WHO Geneva 2002
58. 9. Communicate findings
• During the investigation of an outbreak, timely,
up-to-date information must be communicated to
the hospital administration, department or unit,
and in some cases, to the public.
• Develop a means for disseminating the results to
those who have a need to know (those involved
in improving those outcomes).
• Include measures to prevent such outbreaks in
the future.
• Media attention desirable if public action needed
59. Write the Final Report
• A final report on the outbreak
investigation should be prepared
• It should describe the outbreak,
interventions, and effectiveness, and
summarize the contribution of each team
member participating in the investigation.
• It should also make recommendations to
prevent future occurrence.
• This report can be in the medical
literature, and may be considered as a
legal document.
60. 10. Maintain surveillance
• Follow-up investigation to determine if
there are additional case-patients
• Decide if outbreak is over
• Document effectiveness of control
measures
• Determine if the outbreak has spread
outside its original area or the area where
the interventions were targeted.
62. Example of a Hospital
Outbreak Investigation
• March 25, 2017, a report was received that there
were 12 cases of neonatal sepsis in the Neonatal
intensive Care Unit (NICU).
• The first case was reported on March 4:
Klebsiella pneumoniae was isolated from a
preterm baby with severe respiratory distress.
• Within a period of three weeks from the day the
first case was reported, 11 neonates developed
culture proven K. pneumoniae septicemia.
• Nine of the 12 (7 male, 5 female) septicemic
neonates were preterm (75% preterm), 3 were
fullterm.
63. Example #1
• First clinical manifestation occurred at a mean of
4.8 + 0.43 days after admission (range 3-10days).
• Main presenting complaint: respiratory distress
associated with lethargy and feeding difficulties.
• Disseminated intravascular coagulation (DIC)
seen in 6 neonates
• Necrotizing enterocolitis (NEC) seen in 3
neonates
• Deaths: 10 deaths due to septic shock (83%).
64. Outbreak Investigations:
The 10-Step Approach
1. Identify investigation team and resources
2. Establish existence of an outbreak
3. Verify the diagnosis
4. Construct case definition
5. Find cases systematically and develop line listing
6. Perform descriptive epidemiology/develop
hypotheses
7. Evaluate hypotheses/perform additional studies as
necessary
8. Implement control measures
9. Communicate findings
10. Maintain surveillance
65. Is there an Outbreak?
Month
Total No. of
NICU patients
No. of
HCAI
HCAI
nosocomial)
infection)
Rate
January
2017 148 6 4.05%
February
2017 145 4 2.75%
March
2017 150 12 8.0%
66. Outbreak Investigations:
The 10-Step Approach
1. Identify investigation team and resources
2. Establish existence of an outbreak
3. Verify the diagnosis
4. Construct case definition
67. Verify the diagnosis
• Review existing data
– Medical records/charts
– Surveillance records
– Microbiology
– Other Laboratory reports and records
• Interview unit medical/clinical
personnel and paramedical staff
• Clinical observations
68. Case Definition: Outbreak of
Sepsis (Bloodstream Infection)
Person
Place
• Patient ≤ 1 year of age has at least
one of the ff SSx : fever (>38.0oC),
hypothermia (<36.0oC), apnea, or
bradycardia AND K. pneumoniae
identified from blood is not related to
an infection at another site
Time
Components of
Case Definition
Lab-Confirmed Bloodstream
Infection Criteria (LCBI)
• Occurring after admission to
the NICU
• During March 1-31, 2017
69. Outbreak Investigations:
The 10-Step Approach
1. Identify investigation team and resources
2. Establish existence of an outbreak
3. Verify the diagnosis
4. Construct case definition
5. Find cases systematically and develop line listing
70. Example #1: List of Patients with Klebsiella
pneumoniae Nosocomial Sepsis
Px AOG DOB Date of
onset
Umbilic
cannula
Mech.
Vent
NGT NEC DIC Died
1 Preterm 2/25/17 3/4/17 Y N Y Y N N
2 Fullterm 2/27/17 3/8/17 Y N N N Y Y
3 Fullterm 2/28/17 3/8/17 Y N N N N N
4 Preterm 2/28/17 3/10/17 Y Y Y N N Y
5 Preterm 2/28/17 3/10/17 N Y N N N Y
6 Preterm 3/3/17 3/10/17 Y Y N N N Y
7 Preterm 3/5/17 3/12/17 Y Y N N N Y
8 Fullterm 3/6/17 3/12/17 N N N N Y N
9 Preterm 3/9/17 3/14/17 Y Y N N Y Y
10 Preterm 3/20/17 3/24/17 Y Y N N Y Y
11 Preterm 3/21/17 3/25/17 Y Y N Y Y Y
12 Preterm 3/22/17 3/25/17 Y Y N Y Y Y
71. Outbreak Investigations:
The 10-Step Approach
1. Identify investigation team and resources
2. Establish existence of an outbreak
3. Verify the diagnosis
4. Construct case definition
5. Find cases systematically and develop line listing
6. Perform descriptive epidemiology/develop
hypotheses
72. Example #1:
Epi Curve of NICU Outbreak
Point Source Epidemic
curve – suggests same
source over a relatively
brief period
73. What do we know about Klebsiella
pneumoniae sepsis?
• Klebsiella pneumoniae has been incriminated in
hospital acquired infections.
• This organism colonizes the bowel and skin and
is probably transmitted via medical staff hands.
• Nosocomial K. pneumoniae infection is
associated with a high mortality in neonates and
antimicrobial therapy in infections has been
complicated by the emergence of multi-resistant
strains.
74. Example #1: NICU admissions and
staffing
• Average number of monthly NICU admissions: 145 (range
135 – 155)
• At any one time, there are 12-20 neonates requiring
mechanical ventilation
• Nurse staffing has always been a problem, as shown
below:
Level of Care Nurse-to-patient Ratio
Actual Optimal*
Newborns requiring only routine care 1:12-15 1:6- 8
Newborns in transition/ req close
observation
1:6-8 1:4
Newborns requiring intermediate care 1:6-8 1: 2-3
Newborns requiring intensive care 1:4 1: 1-2
*AAP and American College of Obstetricians Gynecologists. (2012). Guidelines for Perinatal Care, 7th Edition. Elk
Grove Village, IL; National Association of Neonatal Nurses. Position Statement #3009. Minimum RN Staffing in
NICUs. Revised July 2008.
75. Example #1: Environmental
Surveillance Culture Results
• Environmental surveillance cultures
identified the isolates to be the
following:
Bacterial Isolate Location
Klebsiella pneumoniae Ventilator tubings and rinsing
bottles
2 out of 6 sinks sampled in the high
risk area
Coagulase negative
Staphylococcus
2 Feeding cups out of 10 sampled
Enterobacter sp. 1 incubator out of 10 in the high risk
area
76. Example #1: Hypothesis on Possible
Sources of Infection
Potential exposure or
Source
Examples
Contaminated Medical
Device
ventilator tubings, suction tubings. Intravascular
lines (central or peripheral), umbilical cannula
Contaminated patient
care materials or
equipment
Drugs, IV fluids, thermometers, breastmilk
collection and storage equipment, feeding bottles
or feeding cups; malfunction of disinfection
/sterilization machines
Improper Procedures
or techniques
Improper handwashing and hand hygiene
procedures; Inadequate aseptic techniques in
intubation, suctioning, etc;
Environment inadequate or improper cleaning and
disinfection/sterilization ; contaminated or
ineffective disinfectants
Staffing High nurse-to-patient ratio; crossing of nurses
between ‘clean” and “infected” areas
Others Contaminated breastmilk
Others?
77. Outbreak Investigations:
The 10-Step Approach
1. Identify investigation team and resources
2. Establish existence of an outbreak
3. Verify the diagnosis
4. Construct case definition
5. Find cases systematically and develop line listing
6. Perform descriptive epidemiology/develop
hypotheses
7. Evaluate hypotheses/perform additional studies as
necessary
8. Implement control measures
78. Case #1: What are the Infection
Control Measures recommended to
control this outbreak?
Recomendations Yes or No
Hand hygiene
Standard (universal) precaution
Isolation precautions : contact, droplet, and airborne
spread
Environmental cleaning and disinfection
Disinfection and sterilization of medical devices and
patient care equipment
Enhanced healthcare provider education and training
Cohorting patients
Maintain adequate staffing levels
Others:
e.g. Closing of unit
Ye
s
Ye
s
Ye
s
Ye
s
Ye
s
Ye
s
Ye
s
Ye
s
Ye
s
79. Outbreak Investigations:
The 10-Step Approach
1. Identify investigation team and resources
2. Establish existence of an outbreak
3. Verify the diagnosis
4. Construct case definition
5. Find cases systematically and develop line listing
6. Perform descriptive epidemiology/develop
hypotheses
7. Evaluate hypotheses/perform additional studies as
necessary
8. Implement control measures
9. Communicate findings
10. Maintain surveillance
80. Important Points
• Epidemiologic investigations are
essential to determine source of
outbreaks
• Be systematic, consider each step
• Follow the steps if appropriate
• Multiple steps may happen at once
• Might need to repeat steps