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Case-Control Investigation of a Drug-Resistant

Acinetobacter baumannii Outbreak at a Regional

Medical Center in Eastern Kentucky, 2010

Alexander J. Freiman, MPH, CPH CDC/CSTE Applied Epidemiology

FellowKentucky Department for Public

HealthJune 15, 2011

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Background A. baumannii

Aerobic, gram negative bacteria Persist in environment Person-person or direct contact Drug resistance

Outbreaks of multi drug-resistant (MDR) A. baumannii in healthcare setting a growing concern Healthcare-associated infection Especially in intensive care units (ICUs)

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Background Kentucky Department for Public

Health (KDPH) notified of Acinetobacter outbreak in September, 2010 66 cases initially reported

Assistance requested from KDPH New Infection Preventionist Reported gaps in infection control

process Hand hygiene Lacked comprehensive environmental

cleaning protocols

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Background Response team assembled from

KDPH and began on-site evaluation CDC collaboration

Medical epidemiologist Laboratory experts

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Objectives Two main objectives

Identify risk factors associated with recovery of A. baumannii in hospitalized ICU patients

Investigate potential environmental sources of A. baumannii in healthcare facility

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Methods Study Design

Case-control Case definition:

Laboratory-confirmed cultures of MDR A. baumannii ≥72 hours after hospital admission

ICU admission January-September 2010

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Methods Control definition

ICU admission December 2009-October 2010 No history of A. baumannii infection in

chart Controls were matched to cases 1:1

ICU admission date ICU length of stay

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Methods Abstracted information from medical

records Demographics Admission/discharge Medical history Laboratory results Consultations Procedures Medications

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Methods Statistical Analysis

Frequencies T-test, Chi square test, Fisher’s exact

test Odds ratios between potential risk

factors and MDR A. baumannii recovery using logistic regression

Univariate Multivariate

Conducted using SPSS software

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Methods Collected environmental samples

using wide sponge culturettes Site selection

High touch surfaces in areas with infected patients

Identified in previous studies CDC recommendations

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Methods One sample taken at each of five

sites ICU glucometer ICU medication dispensing unit ICU nursing station digital camera Portable x-ray machine Countertops in radiology unit

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Methods Five environmental and three

patient samples sent to state and CDC labs for pulsed field gel electrophoresis (PFGE) typing

Similarity between strains from environmental and patient samples determined using computer software

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Case Selection

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Case Selection

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Case Selection

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Case Selection

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Results

Jan Feb Mar Apr May Jun Jul Aug Sep02468

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Epidemic curve for MDR A. baumannii cases in an eastern Kentucky regional

medical center, 2010 (N=30)

Month

Num

ber

of c

ases

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ResultsSelected Characteristics of Cases and Controls

Characteristic Casen (%)

Controln (%) P value

Race/EthnicityCaucasian 29 (97) 29 (97) 1.00Non-Hispanic 29 (97) 29 (97) 1.00

Age (in years)Mean 68 67 0.72Median 70 69Range 40-87 38-105

SexFemale 12 (40) 17 (57) 0.30

ComorbidityDiabetes 18 (60) 10 (33) 0.04

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Results

Source of MDR A. baumannii culture from cases (N=30)

Source n (%)Respiratory 19 (63)Blood 5 (17)Wound 4 (13)Urine 2 (7)

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Results

Environmental culture results Site ResultPortable x-ray machine PositiveICU nursing station digital camera

Positive

ICU medication dispensing unit NegativeICU glucometer NegativeCountertops in radiology unit Negative

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Results

Patient 4 from another healthcare facility

*

*

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Results

Patient 4 from another healthcare facility

*

*

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Results

Patient 4 from another healthcare facility

*

*

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Results

Patient 4 from another healthcare facility

*

*

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ResultsCrude Associations for Risk Factors and Positive MDR

A. baumannii CultureRisk Factors OR P value 95% Confidence IntervalReceived subcutaneous or intravenous insulin 4.97 0.014* (1.39, 17.82)Fingersticks performed 5.02 0.025* (1.23, 20.49)Total number of chest x-ray procedures 1.10 0.032* (1.01, 1.21)Diabetic 3.00 0.041* (1.05, 8.60)Central line performed 3.14 0.043* (1.03, 9.55)Decubitis ulcer present 2.62 0.072 (0.92, 7.46)Consulted with occupational therapist 3.08 0.094 (0.82, 11.50)Did patient have cardiovascular issues 3.27 0.107 (0.77, 13.83)Obese 2.41 0.111 (0.82, 7.10)*p value ≤ 0.05

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ResultsCrude Associations for Risk Factors and Positive MDR

A. baumannii CultureRisk Factors OR P value 95% Confidence IntervalReceived subcutaneous or intravenous insulin

4.97 0.014* (1.39, 17.82)

Fingersticks performed 5.02 0.025* (1.23, 20.49)Total number of chest x-ray procedures 1.10 0.032* (1.01, 1.21)Diabetic 3.00 0.041* (1.05, 8.60)Central line performed 3.14 0.043* (1.03, 9.55)Decubitis ulcer present 2.62 0.072 (0.92, 7.46)Consulted with occupational therapist 3.08 0.094 (0.82, 11.50)Did patient have cardiovascular issues 3.27 0.107 (0.77, 13.83)Obese 2.41 0.111 (0.82, 7.10)*p value ≤ 0.05

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ResultsCrude Associations for Risk Factors and Positive MDR

A. baumannii CultureRisk Factors OR P value 95% Confidence IntervalReceived subcutaneous or intravenous insulin 4.97 0.014* (1.39, 17.82)Fingersticks performed 5.02 0.025* (1.23, 20.49)Total number of chest x-ray procedures 1.10 0.032* (1.01, 1.21)Diabetic 3.00 0.041* (1.05, 8.60)Central line performed 3.14 0.043* (1.03, 9.55)Decubitis ulcer present 2.62 0.072 (0.92, 7.46)Consulted with occupational therapist 3.08 0.094 (0.82, 11.50)Did patient have cardiovascular issues 3.27 0.107 (0.77, 13.83)Obese 2.41 0.111 (0.82, 7.10)*p value ≤ 0.05

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ResultsAdjusted Associations for Risk Factors and MDR

A. baumannii Culture for Sampled EquipmentRisk Factors OR P value 95% Confidence IntervalFingersticks performed* 4.34 0.048 (1.01, 18.62)Total number of chest x-ray procedures† 1.10 0.065 (0.99, 1.22)Decubitis ulcer photographed* 2.71 0.083 (0.88, 8.37)*Model adjusted for age, type of admission, and mechanical ventilation†Model adjusted for age, type of admission, and fingersticks

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ResultsAdjusted Associations for Risk Factors and MDR

A. baumannii Culture for Sampled EquipmentRisk Factors OR P value 95% Confidence IntervalFingersticks performed* 4.34 0.048 (1.01, 18.62)Total number of chest x-ray procedures† 1.10 0.065 (0.99, 1.22)Decubitis ulcer photographed* 2.71 0.083 (0.88, 8.37)*Model adjusted for age, type of admission, and mechanical ventilation†Model adjusted for age, type of admission, and fingersticks

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Discussion Lab cultures identified two possible

sources for MDR A. baumannii transmission to patients in the facility Portable chest x-ray machine Digital camera used for wound

photography PFGE pattern similarity between

environmental and patient samples matched between 92-100%

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Discussion Epidemiologic analysis suggests

receiving fingersticks is a risk factor for becoming a case

Breakdowns in disease prevention activities Hand hygiene Cleaning shared equipment

Lack of clear equipment-cleaning responsibility might have contributed to ongoing transmission

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Discussion Limitations

Generalizability Small sample

Reliability Cases: Controls only 1:1

Validity Lack of true electronic medical records Incomplete line listing from healthcare

facility

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Discussion Have procedures in place to clean all

shared equipment Recognition of an outbreak and

immediate implementation of effective controls is CRITICAL to preventing MDR A. baumannii transmission in the healthcare setting

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AcknowledgmentsKentucky Department for Public HealthMargaret A. Riggs, PhD, MPH, MAFontaine Sands, DrPH, MSN, CICDavid R. Reese, MA, MPH, FRSPHKraig E. Humbaugh, MD, MPHDoug Thoroughman, PhD, MSRobert L. Brawley, MD, MPH, FSHEA

Centers for Disease Control and Prevention, Division of Healthcare Quality and PromotionAlexander J. Kallen, MD, MPHJudith Noble-Wang, PhDHeather A. O’Connell, PhD

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Acknowledgments This study was supported in part by

an appointment to the Applied Epidemiology Fellowship Program administered by the Council of State and Territorial Epidemiologists (CSTE) and funded by the Centers for Disease Control and Prevention (CDC) Cooperative Agreement Number 5U38HM000414.

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Contact InformationAlex Freiman

CDC/CSTE Applied Epidemiology Fellow

Kentucky Department for Public Health

Phone: (502)564-3261 x3278Email: Alex.Freiman@ky.gov