1492
flagged history of (1) methicillin-resistant Staphylococcus aureus (MRSA); (2) vancomycin-resistant Enterococcus (VRE); (3) Clostridioides difficile; (4) multidrug-resistant gram-negative (MDRGN) bacteria; (5) CRE (which are classified separately from other MDRGNs at JHH); (6) respiratory viruses; and (7) other indications, including “CRE rule-out” for patients recently hos- pitalized internationally (≤6 months),2 enteric pathogens, and contact precautions without associated infection control flag(s).
Statistical methods
Descriptive statistics for contact precaution status and indications were calculated. The relationship between these variables and CRE or CP-CRE colonization was evaluated using univariable logistic regression with general estimating equations and robust standard errors to account for patient-clustering due to repeat unit admissions. Results were summarized as odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Analyses were performed in STATA version 13.0 software (StataCorp, College Station, TX). The Johns Hopkins University School of Medicine Institutional Review Board approved this study with a waiver of consent.
Results
In total, 3,784 unit admissions occurred during the study period: 2,034 (54%) in the MICU and 1,750 (46%) in the transplant unit. Of these encounters, 3,249 (86%), representing 2,424 unique patients, had stored perirectal admission screening swabs. Overall, 126 of 3249 admission swabs (3.9%) (from 117 unique
patients), tested positive for 1 or more CRE (95% CI, 3.2%–4.6%). The CRE prevalence was higher among MICU admissions com- pared to transplant unit admissions (4.7% vs 2.8%; P = .01). Of the 126 CRE-positive swabs, 26 (21%) were positive for carba- penemase production (from 24 unique patients), yielding a CP- CRE admission prevalence of 0.8% (95% CI, 0.5%–1.2%). The prevalence of CP-CRE was similar in both units (0.8% in the MICU vs 0.9% in the transplant unit; P = .74). Most CP-CRE isolates were Klebsiella pneumoniae (46%), followed by Enterobacter cloacae (35%), Citrobacter amalonaticus (11%), and Escherichia coli (8%). During the study period, 817 patients (25%) were on contact precautions at unit admission. Most patients with perirectal CRE and CP-CRE colonization (72 [57%] and 13 [50%], respectively) were not on contact precautions at unit entry. Relative to non- carriers, however, CRE and CP-CRE carriers were more likely to be on contact precautions: ORs, respectively: 2.18 (95% CI, 1.50– 3.15) and 2.93 (95% CI, 1.28–6.72). The most common infection control flag indication(s) among CRE carriers were a history of VRE (46%), MRSA (39%), or MDRGN organisms (39%) (Fig. 1). Patients with an MDRGN history were nearly 3.5 times more likely to test positive for CRE (OR, 3.42; 95% CI, 1.83–6.36) (Table 1). Also, 3 CRE carriers (all CP-CRE-negative MICU patients) had documented recent international hospitalization: 1 patient was not on contact precautions at unit admission, and 2 patients were already isolated for history of MDRGNs. Of 26 patients who had CP-CRE isolated on admission peri-
rectal surveillance, 2 patients were already on contact precautions with a CRE ‘flag’ because of a prior CRE-positive culture (unre- lated to study screening). In 16 additional encounters, patients were isolated based upon an institutional CRE flag, but they tested
Fig. 1. Indications for contact precautions among non–CP-CRE (n=59) and CP-CRE (n=13) colonized patients who were on contact precautions at unit admission. There were 126 CRE carriers (overall) during the study period (100 non–CP-CRE and 26 CP- CRE), 57% of whom (72, 59 non–CP-CRE and 13 CP-CRE) were on contact precautions at unit admission. Note. MRSA, methicillin-resistant Staphylococcus aureus; VRE, vancomycin-resistant Enteroccocus; MDRGN, multidrug-resistant gram-negative bacteria (defined as gram-negative rods other than nonfermenters resistant to 3 of 5 antibiotic classes, nonfermenters resistant to 4 of 5 antibiotic classes, trimethoprim and sulfamethoxazole-resistant Stenotrophomonas spp, extended-spectrum β-lacta- mase (ESBL)–producing bacteria, and/or specified Enterobacteriaceae resistant to ceftriaxone); CRE, carbapenem-resistant Enterobacteriaceae (defined as resistance to any carbapenem); C. diff, Clostridioides difficile; Resp. Virus, respiratory viruses; and Other, other indications, including enteric pathogens, “CRE Rule-Out” for recent internationally hospitalized patients, and unspecified reasons. Percentages exceed 100%, due to >1 possible indication per patient.
Table 1. Association Between Colonization and Indication for Contact Pre- cautions at Unit Admission, Comparing CRE or CP-CRE Carriers to Noncarriers
CRE Covariate
On contact precautions
Indication(s)a: MRSA VRE
MDRGN CRE
Odds Ratio (95% CI)
P Value CP-CRE
Odds Ratio (95% CI)
P Value 2.18 (1.50–3.15) <.001 2.93 (1.28–6.72) .01 1.00
1.68 (0.90–3.13) 1.38 (0.75–2.54)
N/A 1.00 N/A
.01 1.60 (0.38–6.77) .52 .30 1.31 (0.35–4.97) .69
Clostridioides difficile 1.05 (0.43–2.55) Respiratory virus Other
0.60 (0.20–1.74) 0.68 (0.34–1.33)
3.42 (1.83–6.36) <.001 2.20 (0.54–9.02) .27 3.31 (0.58–18.87) .18 8.95 (0.96–83.60) .05 .92 0.82 (0.06–12.0) .88 .34 No observations N/A .26 1.24 (0.34–4.50) .74
Note. CRE, carbapenem-resistant Enterobacteriaceae; CP-CRE, carbapenem-resistant Enter- obacteriaceae; CI, confidence interval; MRSA, methicillin-resistant Staphylococcus aureus; VRE, Vancomycin-resistant Enterococcus; MDRGN, multidrug-resistant gram-negative; N/A,
not applicable. aIndications analyses were restricted to patients who were on contact precautions at admission.
CP-CRE negative. The sensitivity and specificity of a CRE flag for predicting CP-CRE colonization at unit admission were 7.7% and 99.5%, respectively.
Discussion
Identifying CRE-colonized patients at hospital unit admission can facilitate timely infection control interventions, such as placing colonized patients on contact precautions, to limit healthcare-
Katherine E. Goodman et al
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