Colonization with multidrug-resistant gram-negative bacteria: prolonged duration and frequent cocolonization.

BACKGROUND: The characteristics of colonization with multidrug-resistant gram-negative bacteria (MDRGNB) in the gastrointestinal tract have not been well defined. Characterizing the duration of colonization, clearance of colonization, and frequency of cocolonization would provide important information for the development of interventions targeting the prevention of MDRGNB spread. METHODS: From 31 October 2006 through 22 October 2007, serial rectal cultures were obtained every 3-4 weeks from residents of a long-term care facility. Clearance of colonization was defined as > or = 2 consecutive cultures from which MDRGNB were not recovered. Factors associated with clearance of colonization were analyzed using time-to-event methods. RESULTS: Thirty-three patients colonized with 57 MDRGNB isolates were followed up for a median of 211 days (range, 63-356 days). Twenty (61%) of the patients were colonized with > or = 1 different MDRGNB species (median, 2 strains; range, 1-4 strains). The median duration of MDRGNB colonization was 144 days (range, 41-349 days). Clearance of colonization with all MDRGNB strains occurred in 3 patients (9%). Clearance of MDRGNB colonization, calculated by colonizing strain, occurred in 22 (39%) of 57 MDRGNB colonization episodes, with a rate of colonization clearance of 2.6 episodes per 1000 days. Clearance of multidrug-resistant Proteus mirabilis colonization occurred in 1 (6.7%) of 15 episodes, compared with clearance of 21 (50%) of 42 colonization episodes due to other MDRGNB species (hazard ratio, 0.1; 95% confidence interval, 0.01-0.78; P = .03). CONCLUSIONS: Patient colonization with MDRGNB is prolonged, and a substantial proportion of patients are colonized with multiple MDRGNB species. Multidrug-resistant P. mirabilis may have a survival advantage in the gastrointestinal tract, compared with other MDRGNB species.

Antibiotic and infection tracking in Minnesota long-term care facilities.

OBJECTIVES: To describe current systems used to track infections, antibiotic use, and antibiotic-resistant infections in Minnesota long-term care facilities (LTCFs). DESIGN: Self-administered multiple-choice survey assessing the methods, frequency, content, and dissemination of information used to track infections and antibiotic use. SETTING: Licensed Minnesota LTCFs providing skilled nursing care to geriatric residents as of June 2005. PARTICIPANTS: Surveys addressed to the director of nursing at 393 eligible LTCFs. MEASUREMENTS: Responses to survey questions, assessed by percentage of all responders. Of the 345 surveys returned, the majority had a system to track infections (94.1%), antibiotics prescribed (80.6%), and antibiotic-resistant infections (86.2%). Most facilities used only a nonelectronic format to track antibiotic use (73.4%) and antibiotic-resistant infections (72.4%). Respondents collected information on antibiotic susceptibility results from cultures of blood (49.0%), urine (53.0%), sputum (50.0%), or wounds (50.0%). One third of attending clinicians were routinely informed of trends in facility antibiotic use. In 42% of facilities, less than 5 hours per month of paid time for an infection control practitioner was provided. Two-thirds of responders (64.2%) described their systems as not or somewhat effective at optimizing appropriate antibiotic use in their facilities. CONCLUSION: Most facilities in Minnesota have a system in place to track infections, antibiotic use, and antibiotic resistance. These systems may not collect or disseminate information effectively enough to identify or address the development of antibiotic resistance. Paid infection control practitioner time is limited.

Brief report: Physician discomfort and variability with disability assessments.

BACKGROUND: Completing a disability assessment is a common physician task; yet, little formal training is available. OBJECTIVE: To assess physician comfort with disability assessments, and evaluate their consistency. DESIGN: We conducted 2 separate surveys. The "Comfort" survey asked physicians to rate their comfort (1 = very uncomfortable to 10 = very comfortable) with 12 potentially uncomfortable tasks, including disability assessment. The second survey described 2 different patients requesting disability assessment, 1 with acute and the other with chronic back pain; participants assigned each a level of disability. PARTICIPANTS: Resident and staff physicians at an urban county hospital. RESULTS: For 54 physicians returning "Comfort" surveys, disability assessment had the lowest average comfort rating (4.3, SD 1.9) compared with all other tasks (mean ratings ranged from 4.8 to 8.0). For the 73 physicians returning the "Disability Cases" survey, 88% found Case 1 qualified for limited employment, but varied on the types of limitations imposed. For Case 2, 39% assigned no disability, 39% limited employment, and 22% full disability. CONCLUSIONS: Our pilot studies support the hypothesis that physicians are not comfortable with disability assessment, and their assessments can be highly variable. Physician discomfort and lack of training may contribute to variability in disability assessments.

Co-colonization with multiple different species of multidrug-resistant gram-negative bacteria.

BACKGROUND: The characteristics of co-colonization with multiple different species of multidrug-resistant gram-negative bacteria (MDRGN) have not been fully elucidated. Quantifying the prevalence of co-colonization and those patients at higher risk of co-colonization may have important implications for strategies aimed at limiting the spread of MDRGN. METHODS: To determine the prevalence of MDRGN colonization, rectal swabs were obtained from 212 residents residing in a 600-bed long-term care facility. Co-colonization was defined as colonization with ≥2 different MDRGN species. Co-colonized residents were compared with residents colonized with a single MDRGN species to identify factors associated with an increased risk for co-colonization. Molecular typing was performed to determine the contribution of cross transmission to the co-colonized state. RESULTS: A total of 53 (25%) residents was colonized with ≥1 MDRGN. Among these, 11 (21%) were colonized with ≥2 different species of MDRGN. A global deterioration score of ≥5 representing advanced dementia and an increased requirement for assistance from health care workers was significantly associated with co-colonization (P = .05). Clonally related MDRGN strains were identified among 7 (64%) co-colonized residents. CONCLUSION: The prevalence of co-colonization with ≥2 different MDRGN is substantial. Cross transmission of MDRGN is a major contributor to the co-colonized state.

Acquisition of multidrug-resistant gram-negative bacteria: incidence and risk factors within a long-term care population.

BACKGROUND AND OBJECTIVE: An improved understanding of the transmission dynamics of multidrug-resistant (MDR) gram-negative bacteria and the mechanism of acquisition in long-term care facilities (LTCFs) could aid in the development of prevention strategies specific to LTCFs. We thus investigated the incidence of acquisition of these pathogens among an LTCF population. DESIGN: Prospective cohort study. SETTING: Three separate wards at a 600-bed LTCF in metropolitan Boston, Massachusetts, during the period October 31, 2006, through October 22, 2007. PARTICIPANTS: One hundred seventy-two LTCF residents. METHODS: A series of rectal samples were cultured to determine acquisition of MDR gram-negative bacteria, defined as absence of MDR gram-negative bacterial colonization at baseline and de novo recovery of MDR gram-negative bacteria from a follow-up culture. Molecular typing was performed to identify genetically linked strains. A nested matched case-control study was performed to identify risk factors associated with acquisition. RESULTS: Among 135 residents for whom at least 1 follow-up culture was performed, 52 (39%) acquired at least 1 MDR gram-negative organism during the study period. Thirty-two residents (62%) had not been colonized at baseline and had acquired at least 1 MDR gram-negative species at follow-up culture, and 20 residents (38%) were colonized at baseline and had acquired at least 1 MDR gram-negative species at follow-up culture. The most common coresistance pattern was resistance to extended-spectrum penicillins, ciprofloxacin, and gentamicin (57 isolates [42.5%]). Genetically related strains of MDR gram-negative bacteria were identified among multiple residents and between roommates. On conditional logistic regression analysis, antibiotic exposure during the study period was significantly associated with acquisition of MDR gram-negative bacteria (odds ratio, 5.6 [95% confidence interval, 1.1-28.7]; P = .04). CONCLUSIONS: Acquisition of MDR gram-negative bacteria occurred frequently through resident-to-resident transmission. Existing infection control interventions need to be reevaluated.

The emerging threat of multidrug-resistant gram-negative organisms in long-term care facilities.

BACKGROUND: Infections caused by antimicrobial-resistant bacteria are associated with substantial morbidity and mortality. Residents of long-term care facilities (LTCF) are among the main reservoirs of antimicrobial-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Multidrug-resistant gram-negative organisms (MDRGN) are emerging as important pathogens among LTCF residents. Data on the clinical epidemiology of MDRGN, especially in comparison to VRE and MRSA, are limited. METHODS: All clinical cultures collected from residents of a 750-bed LTCF for a period of 2 years were analyzed for the presence of MDRGN, VRE, and MRSA. Multidrug resistance among gram-negative bacteria was defined as resistance to three or more antimicrobials or antimicrobial groups including extended-spectrum penicillins (ampicillin/sulbactam or piperacillin/tazobactam), cephalosporins (cefazolin or ceftriaxone), gentamicin, ciprofloxacin, and trimethoprim-sulfamethoxazole (TMP/SMX). RESULTS: A total of 1,661 clinical cultures were included in the analysis. MDRGN were recovered from 180 (10.8%) cultures, MRSA from 104 (6.3%), and VRE from 11 (0.6%). MDRGN were isolated more frequently than MRSA or VRE throughout the study period. The prevalence of MDRGN increased significantly from 7% in 2003 to 13% in 2005 (p = .001). More than 80% of MDRGN isolates were resistant to ciprofloxacin, TMP/SMX, and ampicillin/sulbactam. Resistance to three, four, and five or more antimicrobials were identified among 122 (67.8%), 47 (26.1%), and 11 (6.1%) MDRGN isolates, respectively. CONCLUSIONS: Rates of MDRGN exceeded those of MRSA and VRE and increased throughout the study period. Resistance to multiple, commonly prescribed antimicrobials among MDRGN raises concerns about therapeutic options available to treat MDRGN infections among LTCF residents.

Multidrug-resistant gram-negative bacteria at a long-term care facility: assessment of residents, healthcare workers, and inanimate surfaces.

OBJECTIVE: To characterize the clinical and molecular epidemiology of multidrug-resistant (MDR) organisms in residents, in healthcare workers (HCWs), and on inanimate surfaces at a long-term care facility (LTCF). DESIGN: Point-prevalence study in 4 separate wards at a 600-bed urban LTCF that was conducted from October 31, 2006 through February 5, 2007. PARTICIPANTS: One hundred sixty-one LTCF residents and 13 HCWs. METHODS: Nasal and rectal samples were obtained for culture from each resident, selected environmental surfaces in private and common rooms, and the hands and clothing of HCWs in each ward. All cultures were evaluated for the presence of MDR gram-negative bacteria, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant enterococci. Clinical and demographic information were collected for each enrolled resident. Molecular typing was performed to identify epidemiologically related strains. RESULTS: A total of 37 (22.8%), 1 (0.6%), and 18 (11.1%) residents were colonized with MDR gram-negative bacteria, vancomycin-resistant enterococci, and methicillin-resistant S. aureus, respectively. MDR gram-negative bacteria were recovered from 3 (1.8%) of the 175 environmental samples cultured, all of which were obtained from common areas in LTCF wards. One (7.7%) of the 13 HCWs harbored MDR gram-negative bacteria. Molecular typing identified clonally related MDR gram-negative strains in LTCF residents. After multivariable analysis, length of hospital stay of at least 4 years, fecal incontinence, and antibiotic exposure for at least 8 days were independent risk factors associated with harboring MDR gram-negative bacteria among LTCF residents. CONCLUSIONS: The prevalence of MDR gram-negative bacteria is high among LTCF residents and exceeds that of vancomycin-resistant enterococci and methicillin-resistant S. aureus. Common areas in LTCFs may provide a unique opportunity for person-to-person transmission of MDR gram-negative bacteria.