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, tktaylor@cdc.gov, 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.

References

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