Colonization With Multidrug‐Resistant Organisms in Evacuees After Hurricane Katrina • Author(s): Ulrich Seybold , MD; Nancy White , RN; Yun F. Wang , PhD; J. Sue Halvosa , MSc;Henry M. Blumberg , MDSource: Infection Control and Hospital Epidemiology, Vol. 28, No. 6 (June 2007), pp. 726-729Published by: The University of Chicago Press on behalf of The Society for Healthcare Epidemiologyof AmericaStable URL: http://www.jstor.org/stable/10.1086/518350 .

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infection control and hospital epidemiology june 2007, vol. 28, no. 6

c o n c i s e c o m m u n i c a t i o n

Colonization With Multidrug-ResistantOrganisms in Evacuees After HurricaneKatrina

Ulrich Seybold, MD; Nancy White, RN;Yun F. Wang, PhD; J. Sue Halvosa, MSc;Henry M. Blumberg, MD

After Hurricane Katrina, 50 patients were evacuated to Grady Me-morial Hospital in Atlanta, Georgia, with limited medical records.The infection control department ordered contact precautions for16 patients. Surveillance cultures performed on admission identifiedcolonization with multidrug-resistant (MDR) bacteria in 9 patients(18%). Presence of a wound was the strongest predictor for MDRcolonization. More data are needed to reliably predict MDR bacterialcolonization.

Infect Control Hosp Epidemiol 2007; 28:726-729

In the aftermath of Hurricane Katrina’s second landfall onAugust 29, 2005, more than 10,100 patients were evacuatedfrom the Gulf Coast.1 The transfer of large numbers of pa-tients from a disaster area after the breakdown of the publichealth infrastructure could lead to the introduction of mul-tidrug-resistant (MDR) bacteria into healthcare facilities ac-cepting those patients. In addition, medical records may notbe available when evacuated patients arrive at distant facilities.

The emergence of MDR bacteria, such as vancomycin re-sistant Enterococcus species (VRE), methicillin resistant Staph-ylococcus aureus (MRSA), and multidrug-resistant gram-neg-ative bacteria, over the past decades2 has become a majorchallenge for treating clinicians and infection control pro-grams.3 The Centers for Disease Control and Prevention (CDC)and other groups have recommended the use of contact pre-cautions (ie, gown and glove use by healthcare workers caringfor patients) to limit nosocomial transmission of MDR or-ganisms.4 The Society for Healthcare Epidemiology of Amer-ica (SHEA) has recommended the performance of bacterialsurveillance cultures on admission for patients at high riskfor carriage of MRSA and VRE.5 However, what constituteshigh risk and how best to identify high risk patients has notbeen well defined. The objective of this investigation, there-fore, was to determine the prevalence of and risk factors forMDR bacterial colonization among Hurricane Katrina evac-uees admitted to our hospital.

methods

Fifty Hurricane Katrina evacuees were transferred to GradyMemorial Hospital in Atlanta, Georgia, between September2 and September 21, 2005. Few of these patients arrived withmedical records. Surveillance culture samples were collectedon admission from all 50 patients (50 nares swab samples,

49 perirectal swab samples, and 25 oral swab samples). Initialculture was done on trypticase soy agar plates with 5% sheepblood; identification of genus and species, as well as anti-microbial susceptibility testing of bacterial isolates, wasperformed according to Clinical and Laboratory StandardsInstitute standards. The definition of MDR organisms in-cluded MRSA, VRE, and extended-spectrum b-lactamase(ESBL)–producing gram-negative bacteria; other bacteria re-sistant to multiple classes of antimicrobials were defined asMDR if they met the criteria for highly resistant microor-ganisms detailed in the 2004 Dutch Working Party on In-fection Prevention guidelines.6 All MRSA isolates were ge-notyped using pulsed-field gel electrophoresis (PFGE) anddistinguished on the basis of criteria established by McDougalet al.7 Identification of the Panton-Valentine leukocidin (PVL)genes8 and the SCC mec type9 was performed as describedelsewhere.

Selected patients were placed under enhanced contact pre-cautions4 by the Hospital Epidemiology and Infection ControlDepartment on the basis of certain characteristics deemed tobe associated with a higher risk for MDR bacterial coloni-zation, such as transfer from another healthcare facility, pres-ence of a wound or invasive device, and clinically apparent(nosocomial) infection.

Univariate analysis of potential risk factors for colonizationwith MDR organisms was performed with SAS, version 9.13(SAS), with prevalence odds ratios as the measure of as-sociation. Potential risk factors were compared between thepatients who were colonized with MDR bacteria on admissionto our institution and those whose surveillance cultures wereeither negative for pathogens or grew non-MDR organisms.

results

Table 1 shows patient characteristics for the 50 HurricaneKatrina evacuees admitted to our hospital. The median agewas 53.5 years, and 26 (52%) of the patients were female.Five patients (10%) had been evacuated from long-term carefacilities, and 17 (34%) were evacuated from hospitals. Thir-teen (26%) of the patients had a wound, and 11 (22%) hadan invasive device in place; most dressings appeared to beseveral days old. (Table 1).

Nine (18%) of patients were culture-positive for MDR or-ganisms (3 had positive perirectal culture results only) (Table2): 3 patients were colonized with MDR gram-negative bac-teria only, 2 patients had perirectal cultures that yielded VRE(1 patient’s culture yielded E. faecalis, the other patient’s cul-ture yielded E. faecium), and 4 patients had cultures positivefor MRSA (Table 2). Of those with cultures positive forMRSA, 2 patients had nares colonization with MRSA cloneUSA300 (1 of whom also had perirectal colonization withUSA100), 1 patient had nares colonization with USA1000(this individual also had perirectal colonization with MDR

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multidrug-resistant organisms in katrina evacuees 727

table 1. Characteristics and Univariate Analysis of Risk Factors for Colonization With Multidrug-Resistant (MDR)Bacteria Among 50 Hurricane Katrina Evacuee Patients

Risk factorAll

(N p 50)

Not colonizedwith MDR

bacteria(N p 41)

Colonizedwith MDR

bacteria(N p 9)

Crudeprevalenceodds ratio(95% CI) P a

Contact precautions initiatedb,c 16 (32) 9 (22) 7 (78) 12.4 (2.2-70.7) .003Age, median (range), years 53.5 (0-101) 52 (0-96) 65 (19-101) NA: continuous .31d

Age 171 years (upper quartile) 12 (24) 8 (20) 4 (44) 3.3 (0.72-15.2) .19Female sex 26 (52) 20 (49) 6 (67) 2.1 (0.46-9.6) .47African American race 39 (78) 34 (83) 5 (56) 0.26 (0.05-1.2) .09Location prior to evacuation

Private residence 27 (54) 24 (59) 3 (33) 0.36 (0.08-1.6) .27Long-term care facility 5 (10) 2 (5) 3 (33) 9.7 (1.3-80.0) .03Hospital 17 (34) 14 (34) 3 (33) 0.96 (0.21-4.4) 1.00

Evacuated via shelter 11 (22) 10 (24) 1 (11) 0.39 (0.04-3.5) .66Wheelchair- or bed-boundb 24 (48) 18 (44) 6 (67) 2.6 (0.56-11.6) .28Admission to ICUb 7 (14) 4 (10) 3 (33) 4.6 (0.82-26.0) .10Woundb 13 (26) 7 (17) 6 (67) 9.7 (1.9-48.4) .006Invasive deviceb,e 11 (22) 6 (15) 5 (56) 7.3 (1.5-35.2) .02Systemic antibacterial therapyb 20 (40) 14 (34) 6 (67) 3.9 (0.84-17.8) .13Length of hospital stay, median (range), days 7 (1-44) 7 (1-44) 6 (2-15) NA: continuous .13d

Crude in-hospital mortality 2 (4) 2 (5) 0 0 1.00

note. Data are no. (%) of patients, unless otherwise indicated. Boldface type indicates statistical significance. CI, confidence interval;ICU, intensive care unit; NA, not applicable.a A P-value less than .05 was considered statistically significant. Fisher exact test, except as indicated.b On day of admission.c Whether precautions were initiated was a clinical judgment, made on the basis of, for example, transfer from a healthcare facility, orpresence of a wound or infection.d Student t test.e Any of the following: central venous catheter (CVC), percutaneous drain, external ventricular drain (EVD), percutaneous endoscopicgastrostomy tube (PEG), and/or tracheostomy tube.

table 2. Characteristics of the 9 Patients Evacuated After Hurricane Katrina Who Were Colonized by Multidrug-Resistant Bacteria

Patient

Age inyears;

sex Race or ethnicity

Locationprior to

evacuationWoundpresent

Invasivedevicepresent

Systemicantibacterial

therapy givenon admission Culture sample, organism recovered

1a 51; F African American Hospital Yes Yes Yes Rectal, VR Enterococcus faecalis2a 19; F White LTCF No Yes No Nares and rectal, ESBL Klebsiella oxytoca;

oral, MDR Pseudomonas aeruginosa3a 33; M Hispanic Hospital Yes Yes Yes Rectal, MDR Enterobacter aerogenes4a 65; M African American LTCF Yes Yes Yes Oral, MDR Morganella morganii5a 101; F African American Hospital Yes No Yes Rectal, VR Enterococcus faecium6 50; F African American Home No No No Nares, MRSA USA100 (PVL�)7a 80; F White Home Yes No Yes Nares, MRSA USA1000 (PVL�);

rectal, MDR Escherichia coli8a 74; M Asian LTCF Yes Yes Yes Nares, MRSA USA300 (PVL�);

rectal, MRSA USA100 (PVL�)9 73; F African American Home No No No Nares, MRSA USA300 (PVL�)

note. USA100, USA1000, and USA300 are MRSA clones defined by McDougal et al.7 VR, vancomycin resistant; LTCF, long-term care facility; ESBL,extended-spectrum b-lactamase–producing; MRSA, methicillin-resistant Staphylococcus aureus; PVL�, genes for Panton-Valentine leukocidin not detectedby polymerase chain reaction (PCR) assay; PVL�, genes for Panton-Valentine leukocidin detected by PCR assay.a Enhanced precautions implemented on admission by the Infection Control/Hospital Epidemiology Department.

E. coli), and 1 patient had nares colonization with USA100(Table 2). In addition to the 9 patients with MDR bacterialcolonization, 7 patients were colonized with methicillin-sen-sitive S. aureus, 9 with Proteus species, 3 with non–ESBL-producing Klebsiella species, 3 with Pseudomonas aeruginosa,and 2 with Acinetobacter baumanii.

The Grady Memorial Hospital Epidemiology Departmentstaff correctly identified patients in need of enhanced contactisolation precautions and initiated those precautions on ad-mission for 7 of 9 patients subsequently found to be colonizedby MDR bacteria (sensitivity, 78%). It is worth noting thatthe 2 patients not isolated on admission had exclusively nasal

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728 infection control and hospital epidemiology june 2007, vol. 28, no. 6

colonization with MRSA (patients 6 and 9 in Table 2). En-hanced contact precautions were also ordered for 9 of 41patients subsequently found not to be colonized by MDRbacteria (specificity, 78%).

Risk factors for MDR colonization among the 50 evacueesadmitted as patients were assessed. Results of the univariateanalysis are shown in Table 1. Evacuation from a long-termcare facility (OR 9.7 [95% confidence interval {CI}, 1.3-80])and presence of an invasive device (OR 7.3 [95% CI, 1.5-35]) or a wound (OR 9.7 [95% CI, 1.9-48]) were significantpredictors of MDR bacterial colonization.

discussion

Fifty patients from the Gulf Coast were evacuated to ourinstitution following Hurricane Katrina; most arrived withfew or no medical records and many had evidence of inat-tention to hygienic practices, such as the presence of woundsor catheters with dressings that may not have been changedin some time. The difficult situations following HurricaneKatrina likely explain this observation. Because of the un-certainty in assessing which of these patients might have beencolonized with MDR organisms and the lack of medical re-cords accompanying these patients, we obtained surveillanceculture samples on admission. These culture results dem-onstrated that 9 (18%) of those admitted to our hospital werecolonized with MDR organisms and thus required contactprecautions, given our hospital policies. Both gram-positiveMDR pathogens (MRSA and VRE) and gram-negative MDRpathogens were recovered from culture. MRSA was the mostfrequent MDR pathogen recovered and was found in 4 (8%)of 50 patients. This finding is similar to the prevalence ofMRSA colonization among other adult patients admitted toour institution.10 Molecular typing studies demonstrated that3 of the 4 patients colonized with MRSA had clones tradi-tionally associated with community-acquired infections: 2had PVL-positive MRSA USA300 recovered from culture, and1 had the USA1000 clone recovered, which had not beenpreviously observed in our patient population. AlthoughUSA300 has most commonly been associated with commu-nity-acquired MRSA infections, a recent report from ourgroup has demonstrated its emergence as a cause of noso-comial infections as well.11 Thus, for the patients evacuatedto our institution, it is difficult to judge whether acquisitionof USA300 occurred in the community or in a healthcarefacility.

Univariate analysis identified evacuation from a long-termcare facility (OR 9.7 [95% CI, 1.3-80]) and presence of aninvasive device (OR 7.3 [95% CI, 1.5-35]) or a wound (OR9.7 [95% CI, 1.9-48]) as statistically significant predictors forMDR bacterial colonization. Initial assessment by the hos-pital’s Epidemiology and Infection Control Department staffresulted in a sensitivity of 78% and specificity of 78% for the

prediction of colonization by MDR bacteria. We are not awareof similar investigations of patients evacuated from disasterselsewhere.

However, with the limited number of patients (n p) being the primary limitation of this investigation, more50

data are needed to achieve 2 important goals: to establish areliable predictive model for infection control programs con-cerning isolation precautions and to decide whether targetedor universal surveillance should be used. Using reliable pre-dictors identified in large prospective trials could limit thenumber of surveillance cultures needed to identify colonizedpatients and allow for more rapid implementation of contactisolation precautions.

acknowledgments

Potential conflicts of interest. All authors report no conflicts of interest rel-

evant to this article.

From the Division of Infectious Diseases (U.S., H.M.B.) and Department

of Pathology (Y.F.W.), Emory University School of Medicine, and the Epi-

demiology Department (N.W., S.J.H., H.M.B.) and Clinical Microbiology

Laboratory (Y.F.W.), Grady Memorial Hospital, Atlanta, Georgia; Medical

Policlinic, Ludwig-Maximilians-University, Munich, Germany (U.S.).

Address reprint requests to Henry M. Blumberg, MD, Emory University

School of Medicine, Department of Medicine, Division of Infectious Diseases,

49 Jesse Hill Jr. Dr., Atlanta, GA 30303 (henry.m.blumberg@emory.edu).

Address correspondence to Ulrich Seybold, MD, Emory University School

of Medicine, Department of Medicine, Division of Infectious Diseases, 49

Jesse Hill Jr. Dr., Atlanta, GA 30303 (useybol@emory.edu).

Presented in part: 16th Annual Scientific Meeting of the Society for Health-

care Epidemiology of America (SHEA); Chicago, IL; March 18-21, 2006

(Abstract 117).

Received July 3, 2006; accepted October 27, 2006; electronically published

April 20, 2007.

� 2007 by The Society for Healthcare Epidemiology of America. All rights

reserved. 0899-823X/2007/2806-0016$15.00. DOI: 10.1086/518350

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