Validation of a phage-open reading frame typing kit for rapid identification of methicillin-resistant Staphylococcus aureus (MRSA) transmission in a tertiary hospital

Figures & data

Table 1 Target genes of the kit for POT typing

	POT number		bp	Target genes	Bands indicated in electrophoresis
Reaction	POT1	1	530	mecA	[1]
Mixture 1		2	449	mec gene complex class B	[2]
		3	355	SCCmec type IIa specific	[3]
	POT2	1	304	Tn554	[4]
		2	271	Prophage	[5]
		3	228	Prophage	[6]
		4	197	Prophage	[7]
		5	161	Prophage	[8]
		6	131	Prophage	[9]
		7	104	Prophage	[10]
		8	81	Genomic island	[11]
Reaction	POT1	4	477	Casette chromosome recombinase A2	[1]
Mixture 2		5	388	Genomic island	[2]
		6	320	Genomic island	[3]
		7	273	mec gene complex class A	[4]
	POT3	1	243	Prophage	[5]
		2	197	Prophage	[6]
		3	171	Prophage	[7]
		4	140	Prophage	[8]
		5	115	Prophage	[9]
		6	95	Prophage	[10]
		7	78	Prophage	[11]

Abbreviations: POT, phage-open reading frame typing; PCR, polymerase chain reaction.

Figure 1 Representative phage-open reading frame typing electrophoretic profiles.

Notes: Samples of DNA collected from patients were analyzed by PCR and electrophoresis according to the kit protocol provided by the manufacturer. Sample A (patient number 89, 122-137-80), sample B (patient number 90, 106-137-2), sample C (patient number 91, 106-157-116), sample D (patient number 51, 106-137-80), and sample E (patient number 52, 108-24-80), respectively. Positive control (PC) included in kit. Band size was estimated by positive control markers of mixtures 1 and 2, including fem A gene (601bp: Staphylococcus aureus specific gene).

Abbreviation: PCR, polymerase chain reaction.

Table 2 Overlapping POT types

POT type	Number of cases	Imported cases*	Nosocomial transmission	Total number of wards
106-11-80	2	0	2	2
106-137-2	3	0	3	2
106-137-80	8	2	6	6
106-139-80	2	2	0	2
106-9-2	2	0	2	1
93-137-103	2	0	2	2
93-155-111	7	1	6	4
93-157-61	4	0	4	1
93-182-103	2	0	2	2
93-191-125	2	0	2	1
93-213-109	2	0	2	1
93-221-111	2	0	2	2

Notes:

* Samples of nasal swabs for MRSA culture were taken on admission and every 7 days thereafter. Therefore, “imported” (in contrast to “acquired”) means that MRSA was isolated on admission (usually within 48 hours).

Abbreviations: POT, phage-open reading frame typing; MRSA, methicillin-resistant Staphylococcus aureus.

Table 3 Profiles of patients defined as having nosocomial infection

Patient number	Ward	POT number	Department	Sex	Data (month/day)
1	A	106-137-2	Emergency	M	9/16
2	A	106-137-2	Emergency	F	9/30
3	A	106-137-80	Emergency	M	6/10
4	A	106-137-80	Emergency	F	6/24
5	A	106-139-80	Emergency	M	7/22
6	A	106-9-2	Emergency	M	6/10
7	A	106-9-2	Emergency	M	6/17
8	B	93-155-111	Hematology	M	9/2
9	C	106-11-80	Otolaryngology	F	9/2
10	C	93-155-111	Otolaryngology	M	7/1
11	C	93-155-111	Otolaryngology	M	6/24
12	C	93-182-103	Otolaryngology	F	6/24
13	C	93-221-111	Otolaryngology	M	7/8
14	D	106-137-80	Transplant center	M	9/16
15	E	106-137-80	Pediatrics	M	7/8
16	F	93-182-103	Neurology	F	6/10
17	F	93-213-109	Neurology	F	6/10
18	F	93-213-109	Neurology	F	7/1
19	G	93-137-103	Cardiology	M	6/17
20	H	106-137-80	Surgery	M	7/8
21	H	106-137-80	Surgery	M	8/5
22	H	93-155-111	Surgery	M	7/12
23	H	93-155-111	Surgery	M	9/30
24	H	93-155-111	Surgery	F	9/30
25	I	93-221-111	Surgery II	M	9/16
26	J	106-11-80	Urology	M	7/29
27	K	93-137-103	Nephrology	F	9/30
28	L	106-137-2	ICU	M	9/16
29	M	106-137-80	Orthopedics	F	9/2
30	N	106-139-80	Ophthalmology	M	7/29
31	O	93-191-125	Dermatology	F	7/12
32	O	93-191-125	Dermatology	F	6/17
33	P	106-137-80	Cardiosurgery	F	7/29
34	P	93-155-111	Cardiosurgery	M	7/1
35	P	93-157-61	Cardiosurgery	M	6/17
36	P	93-157-61	Cardiosurgery	M	8/5
37	P	93-157-61	Cardiosurgery	F	9/16
38	P	93-157-61	Cardiosurgery	F	9/2

Abbreviations: POT, phage-open reading frame typing; ICU, intensive care unit; M, male; F, female.