Table 1.

Epidemiologic Analysis of 33 Patients With Clostridium difficile Infections Classified as Hospital-Acquired at the University of Pittsburgh Medical Center, July–November 2009

Study Day	MLVA Complex	tcdC Genotype	Same Unit	Same Bed	Concurrent Hospital Stay	Dates of Exposure to Sourcea	Classification of Presumed Sourceb	No. of Days Between Source and Patient Culture	Classification of Most Likely Transmission Category	STRD (Source to Case)
9	F	1	No	No	Yes	−6 to 0	2	−6	Non–ward CDI	3
10	K	1	Yes	No	Yes	−2 to −1	6	−28	Ward CDI	0
12	F	1	Yes	Yes	Yes	−7 to −3	2	−9	Environmental	1
16	A	3	Yes	No	Yes	−5 to 0	3	−8	Ward CDI	0
19	M	1	No	No	Yes	−7 to 0	6	−9	Non–ward CDI	5
27	C	1	Yes	No	Yes	−6 to 0	1	−1	Ward carrier	0
33	F	1	No	No	Yes	−11 to −5	4	−11	Non–ward carrier	0
37c	M	1	Yes	No	Yes	−6 to −6	6	−12	Ward CDI	5
44	S	1	Yes	Yes	Yes	−24 to −22	2	−7	Environmental	0
45	M	1	Yes	No	Yes	−7 to −4	2	−8	Ward CDI	0
47	W	5	No	No	Yes	−12 to −11	5d	−11	Non–ward carriera	0
48c	M	1	Yes	No	Yes	−13 to −1	1	−4	Ward carrier	3
62	C	1	No	No	Yes	−17 to 0	6	−1	Non–ward CDI	2
68	Q	20	No	No	Yes	−24 to −21	1	−25	Non–ward carriere	3
71	V	19	No	No	Yes	−34 to −14	7	−14	Non–ward carrier	0
71c	U	42	No	No	No	Unknown	1	−34	Indeterminatee	1
75	N	1	Yes	Yes	No	−6 to −6	1	−18	Environmental	0
90	C	1	No	No	Yes	−16 to 0	7	−10	Non–ward carrier	1
93c	B	3	No	No	Yes	−25 to −8	1	−15	Non–ward carriere	2
94c	J	1	No	No	Yes	−50 to −39	4	−43	Non–ward carriere	1
94	J	1	No	No	Yes	−55 to −40	4	−44	Non–ward carrier	1
94	M	1	No	No	Yes	−12 to −12	4	−16	Non–ward carriere	4
101	M	1	Yes	No	Yes	−6 to −1	2	−6	Ward CDI	0
101	H	1	No	No	No	Unknown	1	−35	Indeterminate	3
114	J	1	No	No	Yes	−4 to 0	4	−4	Non–ward carrier	0
117	J	1	No	No	Yes	−2 to 0	2	−3	Non–ward CDI	0
119	G	1	Yes	No	Yes	−3 to 0	6	−8	Ward CDI	0
120	H	1	Yes	No	Yes	−6 to −6	2	−14	Ward CDI	2
120	J	1	No	No	Yes	−21 to 0	2	−7	Non–ward CDI	0
120	J	1	No	No	Yes	−21 to 0	2	−7	Non–ward CDI	0
125	J	1	No	No	Yes	−10 to 0	2	−5	Non–ward CDI	0
126	D	1	Yes	Yes	Yes	−12 to −12	4	−15	Environmental	3
127	H	1	No	No	Yes	−12 to −4	2	−7	Non–ward CDI	1

Patients for whom an isolate was unavailable for genotyping (n = 6) and with Clostridium difficile having unique MLVA genotypes (n = 17) or isolates that were chronologically first within a complex of highly related isolates (n = 5) are not depicted. MLVA cluster designations conform to those in Figure 2 and Supplementary Table 1, whereas source classification and presumed transmission category conform to definitions outlined in the Methods section.

Abbreviations: CDI, Clostridium difficile infection; MLVA, multilocus variable number of tandem repeats analysis; STRD, summed tandem-repeat difference.

^a Relative to patient's toxin testing date.

^b 1 = discrepant carrier; 2 = C. difficile infection acquired at University of Pittsburgh Medical Center (UPMC); 3 = hospital-acquired colonization with C. difficile detected by toxin test ordered by clinician; 4 = indeterminate carrier; 5 = other CDI (infection not acquired at UPMC)^a; 6 = recurrent; 7 = persistent carrier.

^c Indicates CDI that was attributable to UPMC after discharge (community-onset, healthcare facility–associated).

^d Source patient's first positive toxin test occurred on study day 50 after having positive screening cultures on days 15, 22, 36, and 49.

^e Source patient was positive for other organism requiring isolation prior to screening positive for C. difficile.