c.difficilecolonization and ribotypes in hong kong 783
methods Study Design
We conducted a prevalence study involving 8 nursing homes in the Kowloon West region of Hong Kong, China, between October 2, 2012, and August 15, 2014. We obtained verbal informed consent from all enrolled residents or from the next- of-kin or the legal guardian. The institutional review boards of the Department of Health and the Hospital Authority of Hong Kong approved the study.
Screening Procedure
Baseline stool samples were collected to determine the pre- valence of C. difficile colonization among nursing home resi- dents. In addition, we conducted a prospective study in 4 nursing homes to determine the acquisition of C. difficile colonization. Only residents who had a minimum of 90 days of follow-up were included. Stool samples were collected every 90 days, and additional stool samples were obtained for resi- dents who had been discharged from hospitals. Residents who were C. difficile positive during the study period were included in the Kaplan-Meier estimate of median carriage duration. The C. difficile–positive residents who turned negative but became positive again until the end of the study (N=6) were excluded because intermittent carriage could not be differentiated from a new acquisition.
Microbiological Procedure
Stool samples were plated directly onto ChromID C. difficile agar plates (CDIF, bioMérieux, Marcy-l'Étoile, France), which were then incubated in an anaerobic chamber for 48 hours. Suspected flat and irregular colonies were confirmed to be C. difficile using mass-assisted laser desorption ionization–time of flight(MALDI-TOF)mass spectrometry (Biotyper 3.0, Bruker Daltonik, Germany). All C. difficile isolates were tested for the presence of toxin gene using real-time polymerase chain reaction (PCR, LightMix C. difficile kit; TIBMOLBIOL GmbH, Germany).10 The PCR ribotyping and slpA typing were per- formed for all first isolated C. difficile strains at the baseline sampling or sampling upon nursing home residence, as described previously.11,12
Definitions
A resident who had no history of hospitalization within the past 90 days was defined as having newly acquired C. difficile in the nursing home if a negative baseline stool culture was converted to positive on subsequent sampling. A resident who had been discharged from a hospital was defined as having newly acquired C. difficile in the nursing home if both a negative baseline stool culture and a negative stool culture collected after the last hospitalization turned positive on sub- sequent sampling. Residents at risk were those whose stool
cultures were C. difficile negative. Resident days at risk were the number of days of residence of the residents at risk in the nursing homes. For residents who died or left the nursing homes between visits, the resident days up to the last visit were included. For residents whose specimens converted from negative to positive, the resident days up to the specimen collection date were included. Underlying diseases included cancer, cardiovascular dis-
eases, chronic lung diseases, diabetes mellitus, chronic skin lesions, hepatic diseases, renal failure, and immunodeficiency. Devices included urinary catheters, nasogastric tubes, percu- taneous endoscopic gastrostomy tubes, tracheostomy tubes, and Tenckoff catheters for peritoneal dialysis.
Data Collection
General data regarding the facilities (ie, the resident-to-staff ratio; the number, type, and training frequency of infection control staff; the proportion of residents >75 years of age, the environment cleansing agent used; and the number of hand- washing facilities) were collected (Table 1). The following variables were recorded prospectively on a standardized data collection form at the time of stool collection for the residents who participated in the follow-up study, with supplementation from the electronic hospital medical record system: demo- graphic characteristics, underlying diseases, the functional status (Barthel index),13 the date of residence, the number of residents sharing the room, presence of devices and skin lesions, contact history of C. difficile and history of diarrhea, hospitalization, antibiotics, acid suppressive therapies, and diarrhea within the previous 12 weeks.
Statistical Analysis
The associations of the residents’ characteristics were com- pared using the χ2 test, the Fisher exact test, the t test, and the Mann-Whitney test as appropriate. Odds ratios (ORs) with accompanying 95% confidence interval (CI)were calculated to determine which characteristics were associated with C. diffi- cile colonization and acquisition. Results were considered statistically significant when the 2-sided P value was <.05. Statistical analyses were performed using SPSS version 16.0 software (IBM, Armonk, NY). Univariate analyses were per- formed on single characteristics for C. difficile colonization and acquisition cases. A multivariable logistic regression analysis was then performed on significant characteristics identified in the univariate analysis. We examined the OR and the adjusted odds ratio (aOR) for the effect size.
results
Of the 375 residents, 300 (80.0%) participated in the study. We detected C. difficile isolates in 39 residents (13.0%; 95% CI, 9.7–17.3); of these, 30 isolates (76.9%) were toxigenic. The prevalence of toxigenic C. difficile colonization ranged from
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144
