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Table 1 Risk factors for the occurrence of large outbreaks (≥ 7 patients) as determined by univariate analysis (more than one type may be affected)

From: Health care workers causing large nosocomial outbreaks: a systematic review

Risk factor

Risk factor present

Risk factor lacking

p-value

 

# LO

# all NO

%

# LO

# all NO

%

 

departments (n=150)*

       

surgery

32

76

42.1

44

74

59.1

0.036

neonatology

24

41

58.5

52

109

47.7

0.274

gynecology

14

20

70.0

62

130

47.7

0.091

pediatrics

1

9

11.1

75

141

53.2

0.017

internal medicine

1

2

50.0

75

148

50.7

1.000

other

11

21

52.4

65

129

50.4

1.000

type of ward (n=150)*

       

operating theatre

26

63

41.3

50

87

57.5

0.068

peripheral ward

33

59

55.9

43

91

47.3

0.320

intensive care unit

17

28

60.7

59

122

48.4

0.296

outpatient clinic

4

9

44.4

72

141

51.1

0.744

age groups (n=147)*

       

neonates (≤ 1 m)

24

39

61.5

52

108

48.1

0.191

infants (1 m - 1 y)

3

6

50.0

73

141

51.8

1.000

children (> 1–12 y)

4

14

28.6

72

133

54.1

0.092

adolescents (13–17 y)

9

13

69.2

67

134

50.0

0.249

adults (18–69 y)

49

93

52.7

27

54

50.0

0.864

seniors (≥ 70 y)

13

26

50.0

63

121

52.1

1.000

microorganism (n=152)

       

bacteria

58

108

53.7

19

44

43.2

0.284

viruses

14

34

41.2

63

118

53.4

0.245

fungi

5

10

50.0

72

142

50.7

1.000

species (n=152)

       

S. aureus

26

49

53.1

51

103

49.5

0.730

hepatitis B virus

9

27

33.3

68

125

54.4

0.057

S. pyogenes

12

19

63.2

65

133

48.9

0.328

Candida spp.

5

8

62.5

72

144

50.0

0.719

P. aeruginosa

2

7

28.6

75

145

51.7

0.273

transmission (n=152)

       

contact

53

105

50.5

24

47

51.1

1.000

droplets

8

17

47.1

69

135

51.1

0.801

airborne

11

16

68.8

66

136

48.5

0.860

foodborne

3

6

50.0

74

146

50.7

1.000

unknown

3

13

23.1

74

139

53.2

0.045

HCW characteristics

       

colonization only

43

73

58.9

34

79

43.0

0.054

HWC infected

31

70

44.3

46

82

56.1

0.193

blood borne infection

9

27

33.3

68

125

54.4

0.057

aware of carrier status

3

14

21.4

62

118

52.5

0.045

proper HH compliance

12

21

57.1

9

16

56.3

1.000

work experience > 5 y

9

18

50.0

8

12

66.7

0.536

  1. LO = large outbreak (≥ 7 patients affected); NO = nosocomial outbreak; HCW = health care worker; HH = hand hygiene; *more than one type may be affected.