Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

Persons using assistive technology might not be able to fully access information in this file. For assistance, please send e-mail to: Type 508 Accommodation and the title of the report in the subject line of e-mail.

Carbapenem-Resistant Klebsiella pneumoniae Associated with a Long-Term--Care Facility --- West Virginia, 2009--2011

On January 27, 2011, a West Virginia county health department was notified of a cluster of carbapenem-resistant Klebsiella pneumoniae (CRKP) cases detected by a local hospital (hospital A). CRKP infections frequently are resistant to a majority of antimicrobial agents and have an increased risk for morbidity and mortality (1). The West Virginia Bureau for Public Health (WVBPH) conducted field investigations to identify all cases, characterize risk factors for infection, and abstract data for a matched case-control study. Nineteen case-patients and 38 control patients were identified. Infection with CRKP was associated with admission from or prior stay at a local long-term--care facility (LTCF A). Pulsed-field gel electrophoresis (PFGE) analysis indicated that all five hospital A clinical specimens and all 11 point prevalence survey isolates from LTCF A were closely related. This is the first outbreak of CRKP identified in West Virginia. Recommendations to LTCF A included the following: 1) initiate surveillance for multidrug resistant organisms; 2) revise and improve infection prevention and control activities within the facility; 3) educate residents and their families, physicians, and staff members about CRKP; and 4) identify qualified personnel to coordinate infection control functions within the facility. Although LTCF A has made significant improvements, the outbreak investigation is ongoing. Additional site visits have been conducted, and additional colonized residents have been identified; the last clinical case was detected in July. These findings demonstrate the interconnectedness of the health-care system and factors potentially contributing to transmission of infection. Interventions targeting all levels of care are needed to prevent further CRKP transmission.

In collaboration with the local health department and hospital A, WVBPH conducted an initial field investigation during February 7--9 to identify all cases and characterize infection risk factors. A case was defined as the first detection of CRKP in a patient admitted to a hospital A unit during April 2009--February 2011. Descriptive analysis was conducted to evaluate patient demographics, admitting hospital unit, reason for admission, admitting source for patient, and time between admission and collection of culture specimen.

A second field investigation was conducted during February 21--24 to complete data abstraction for a matched case-control study. Control patients were identified among patients admitted to a hospital A unit with a clinical culture of carbapenem-susceptible K. pneumoniae during April 2009--February 2011. Where possible, each case-patient was matched within 10 years of age with two control patients and by date of specimen collection within 14 days. Data regarding patient demographics, initial admission to hospital A, indwelling devices and procedures, history of multidrug-resistant organisms (MDROs), history of stays in hospital A and LTCFs, and comorbid medical conditions (reported as Charlson comorbidity index scores*) were collected for both case-patients and controls.

Site visits to hospital A and LTCF A were conducted during the initial field investigation. Surveillance data and practices and infection control policies and practices of both facilities were reviewed. A point prevalence survey to identify the baseline prevalence of CRKP was conducted according CDC's recommended protocol (2) in the oncology and medical/surgical units at hospital A and facilitywide at LTCF A.

Data from the field investigation and matched case-control study were analyzed using statistical software. Risk factors for CRKP were assessed by performing exact conditional logistic regression to calculate exact odds ratio (OR) estimates and 95% confidence intervals for dichotomous variables. Because of nonnormal distribution of continuous variables, median two-sample tests were used to estimate statistically significant differences between case-patients and control patients.

A total of 19 cases were identified with specimen collection dates of April 4, 2009--February 21, 2011. Among those cases, 16 patients had been admitted from LTCFs, 14 of whom were from LTCF A (Table 1). Cultures were collected from 10 of the 14 LTCF A case-patients ≤2 calendar days after admission to hospital A, indicating they likely arrived at the hospital with infection.

A total of 38 control patients were identified. Multiple characteristics of case-patients and control patients were compared (Table 1). Age, race, and Charlson comorbidity scores were similar for both groups, but case-patients (58%) were more likely than control patients (16%) to be male. Case-patients had a longer length of hospital stay (mean = 11.4 days) and a higher number of previous hospitalizations (mean = 2.5).

Because of the small number of case-patients, risk factors for CRKP infection (Table 2) were evaluated by exact conditional logistic regression. Risk for CRKP infection was most strongly associated with a prior stay at LTCF A (OR = 46.6) and being admitted from LTCF A (OR = 35.1). Case-patients were significantly less likely than control patients to be ambulatory at the time of diagnosis and to have spent time at home during the previous year.

Hospital A surveillance and infection control practices were determined to be sufficient, whereas evaluation of surveillance and infection control practices at LTCF A revealed deficiencies. The infection preventionist position at LTCF A had been vacant for 9 months. An electronic surveillance system was available, but the facility did not record laboratory reports or MDRO status of residents in this system. LTCF A used a medical laboratory that does not report carbapenem resistance, and no record existed of CRKP infection among LTCF A residents. Staff hand hygiene stations were not conveniently located, and supplies (e.g., gloves, gowns, and waste containers) were missing for compliance with contact precautions. Point prevalence surveys were conducted; none of 29 hospital A patient samples were positive for CRKP, whereas 11 (9%) of 118 resident samples, including eight from residents with previously unrecognized CRKP colonization, were positive from LTCF A. Five clinical isolates from hospital A and 11 surveillance isolates from LTCF A's point prevalence survey were forwarded to CDC for confirmation and PFGE analysis. All 16 isolates were confirmed as carbapenemase (KPC)-producing K. pneumoniae and shared >88% similarity in their PFGE patterns.

Reported by

Diana Gaviria, MD, Victoria Greenfield, Berkeley County Health Dept; Danae Bixler, MD, Carrie A. Thomas, PhD, Sherif M. Ibrahim, MD, West Virginia Bur for Public Health. Alex Kallen, MD, Brandi Limbago, PhD, Brandon Kitchel, MS, Div of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases; Tegwin K. Taylor, DVM, EIS Officer, CDC. Corresponding contributor: Tegwin K. Taylor,, 304-356-4007.

Editorial Note

This report describes the first outbreak of CRKP detected in West Virginia. CRKP is the most common carbapenem-resistant Enterobacteriaceae in the United States (1). CRKP spread has been driven by dissemination of Enterobacteriaceae producing the KPC enzyme, which confers resistance to all beta-lactam antimicrobials (3). Delaying further spread of these organisms, especially in areas where they remain uncommon, is a public health priority. Aggressive infection control interventions have been successful in reducing outbreaks of these organisms in acute care and long-term--care settings (4--6).

CRKP infections frequently are resistant to the majority of antimicrobial agents and are associated with increased morbidity and mortality (1). In one report, nearly half of 99 patients with CRKP infection died during hospitalization (7). CRKP isolates from these patients were resistant to beta-lactams, fluoroquinolones, and sulfonamides, and the isolates demonstrated variable susceptibility to aminoglycosides, polymyxin B, tetracycline, and tigecycline, substantially limiting treatment options (7). CRKP infections resistant to all antimicrobial agents tested, including carbapenems, polymyxin B, and tigecycline, have been reported recently (8).

LTCFs can be a challenging setting for preventing spread of MDRO infections, including CRKP. LTCFs serve as permanent homes for their residents, making restrictions on residents' activities undesirable. In addition, LTCFs often have multiple-occupancy rooms, and residents often share common living areas, including bathrooms, which might facilitate MDRO transmission. In addition, lack of resources, including infection control expertise, often is a concern. LTCF residents typically have underlying health conditions and regular exposure to antimicrobial agents, both of which are risk factors for MDRO colonization and infection. LTCF residents frequently are transferred to acute care hospitals for higher levels of medical care, allowing ample opportunity for movement of an MDRO to these facilities.

Because of the interconnectedness of health-care facilities, successful control of MDROs often requires a regional approach. Local and state health departments are positioned to facilitate and coordinate prevention efforts across the continuum of health care, even in the absence of regulatory authority. In one example of a coordinated regional approach to MDRO control, facilities in a common region implemented active surveillance, enhanced infection control measures (e.g., barrier precautions and hand hygiene), provided staff education, and improved intrafacility communication regarding patients' MDRO status. This community was able to lower its vancomycin-resistant enterococci prevalence in health-care facilities from 2.2% to 0.5% during a 2-year period (9).

With only 19 case-patients, this study sample was small, which restricts the precision of results and the types of analyses that can be conducted for a matched case-control study. Data abstraction relied solely on information provided in Hospital A medical records. Therefore, data for individual case-patients might be inconsistent or missing. Residual confounding is a known limitation of case studies and might exist in this study.

In response to the outbreak, WVBPH recommended that LTCF A group residents with CRKP infection or colonization, use contact precautions during care, conduct active surveillance for CRKP with periodic point prevalence surveys, improve communication of MDRO status when transferring residents to other facilities, and monitor staff member compliance with hand hygiene and contact precautions. This outbreak demonstrated the crucial role that LTCFs can have in the ongoing CRKP spread and verified that local and state health departments are vital to the public health response to MDRO outbreaks.


  1. CDC. Guidance for control of infections with carbapenem-resistant or carbapenemase-producing Enterobacteriaceae in acute care settings. MMWR 2010;58:256--60.
  2. CDC. Laboratory protocol for detection of carbapenem-resistant or carbapenemase-producing, Klebsiella spp. and E. coli from rectal swabs. Atlanta, GA: US Department of Health and Human Services, CDC; 2009. Available at Accessed July 1, 2011.
  3. Kallen, A, Srinivasan, A. Current epidemiology of multidrug-resistant gram-negative bacilli in the United States. Infect Control Hosp Epidemiol 2010;31(Suppl 1):S51--4.
  4. Munoz-Price L, Hayden M, Lolans K, et al. Successful control of an outbreak of Klebsiella pneumoniae at a long-term acute care hospital. Infect Control Hosp Epidemiol 2010;31:341--7.
  5. Gregory C, Llata E, Stine N, et al. Outbreak of carbapenem-resistant Klebsiella pneumoniae in Puerto Rico associated with a novel carbapenemase variant. Infect Control Hosp Epidemiol 2010;31:476--84.
  6. Ben-David D, Maor Y, Keller N, et al. Potential role of active surveillance in the control of a hospital-wide outbreak of carbapenem-resistant Klebsiella pneumoniae infection. Infect Control Hosp Epidemiol 2010;31:620--6.
  7. Patel G, Huprikar S, Factor SH, Jenkins SG, Calfee DP. Outcomes of carbapenem-resistant Klebsiella pneumoniae infection and the impact of antimicrobial and adjunctive therapies. Infect Control Hosp Epidemiol 2008;29:1099--106.
  8. Elemam A, Rahimian J, Mandell W. Infection with panresistant Klebsiella pneumoniae: a report of 2 cases and a brief review of the literature. Clin Infect Dis 2009;49:271--4.
  9. Ostrowsky B, Trick W, Sohn A, et al. Control of vancomycin-resistant enterococcus in health care facilities in a region. N Engl J Med 2001;334:1427--33.

* Additional information is available in Extermann M. Measuring comorbidity in older cancer patients. Eur J Cancer 2000;36:453--71.

What is already known on this topic?

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is the most common carbapenem-resistant Enterobacteriaceae in the United States. CRKP infections often are associated with health-care settings, including long-term--care facilities (LTCFs), whose residents are vulnerable to increased morbidity and mortality caused by CRKP infections.

What is added by this report?

This report describes the first identified outbreak of CRKP in West Virginia, confirming the further spread of CRKP in the United States. In this outbreak, CRKP infection was associated with a local LTCF. Point prevalence studies revealed that intrafacility transmission occurred in the LTCF.

What are the implications for public health practice?

Although control of CRKP is challenging and multifactorial, thorough implementation of infection control interventions has decreased CRKP prevalence in health-care settings. Regional interventions targeting all levels of care are needed to prevent CRKP transmission, and continued CRKP surveillance is needed to further understand its epidemiology.

TABLE 1. Characteristics of carbapenem-resistant Klebsiella pneumoniae case-patients and control patients --- West Virginia, 2009--2011


Case- patients

(n = 19)

Control patients

(n = 38)

Mean age (yrs)

















Reason for admission

Urinary tract infection



Altered mental status






Admitting service







Admitting source

Long-term--care facility A (LTCF A)



Other LTCF






Mean length of stay (days)




Intensive-care unit



Mean days between admission and specimen collection



Mean number of previous hospitalizations



Patient outcome

Discharged home



Discharged to LTCF



Transferred to another health-care facility






Charlson comorbidity index score



TABLE 2. Risk factors for infection with carbapenem-resistant Klebsiella pneumoniae --- West Virginia, 2009--2011

Potential risk factor

Case- patients (n = 19)

Control patients (n = 38)

Odds ratio*

(95% confidence interval)

Prior stay at LTCF A§





Admitted from LTCF A





Prior stay at hospital A





Prior time at home**





Indwelling urinary catheter





History of multidrug-resistant organism










* Calculated by exact conditional logistic regression.

Any documented stay at a LTCF ≤1 year before incident admission to hospital A.

§ Any documented stay at LTCF A ≤1 year before incident admission to hospital A.

Any hospitalization ≤1 year before incident admission to hospital A.

** Any documented time at home ≤1 year before incident admission to hospital A.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

All MMWR HTML versions of articles are electronic conversions from typeset documents. This conversion might result in character translation or format errors in the HTML version. Users are referred to the electronic PDF version ( and/or the original MMWR paper copy for printable versions of official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Road Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO
A-Z Index
  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #