Table 4 Bacterial co-infection reported among hospitalised cases of influenza A(H1N1)pdm09, not requiring ICU (n = 22)

CDC (2009) [59]

California, USA

4/09–5/09

State-wide passive surveillance of notified cases / Hospitalized cases for > 24 h

N = 30

6/30 (20)

4/30 (13.3)

0/23 (0)

7 were still hospitalised

15/30 (50)

5/30 (16.7)

0

0/100 (0)

0/100 (0)

15/25 (60)

CXR Non diff

Jain [60] (2009)

USA

4/09–6/09

Notified cases from 24 state health departments to CDC / Hospitalized ≥24 h

N = 272

67/272 (24.6)

42/272 (15.4)

19/272 (7.0)

200/268 (74.6)

78 (29.1)

206/260 (79.2)

- Pre: 30/198

- on: 117/198

3/182 (1.6)

2/182 (1.1) 1 had positive lung tissue culture)

1/n urinary antigen test

1/n BAL fluid

0/n ET aspirate

- CXR 100/249 (40)

(66 patients with bilateral infiltrates)

26 limited to 1 lobe, 6 limited to multiple lobes

- not diff

Louie [61] (2009)

California, USA

4/09–8/09

State-wide enhanced surveillance /Hospitalized or fatal all ages cases

N = 1088

340/1088 (31.3)

193/297 (64.9)

118/1088 (10.8)

701/884 (79.3)

- 357 (40.4)

NR

46/1088 (4.2)

NR

547/833 (65.7)

- CXR/CT + pos bacterial culture(s) 46

- No diff

Dhanoa [62] (2011)

Malaysia

9/09–5/10

Single-centre case series (retrospective)/ Hospitalised patients all ages

N = 50

9/50 (18.0)

6/50 (12.0)

2/50 (4.0)

50/50 (100)

49 (98.0)

- Pre = 8

- On =41

14/45 (31.1)

total 45 culture samples sent

2/45 (4.4) site NR

25/50 (50)

-CXR + clinical opinion

- No diff

To [63] (2010)

China

6/09–10/09

Single-centre case series (retrospective)/ Hospitalized adult patients

N = 69

28/69 (40.6)

26/69 (37.7)

- NS

13/69 (18.8)

69/69 (100)

37/69 (53.6)

- On = 37

0/69 (0)

0/69 (0)

25/69 (36.2)

CXR Non-diff

Viasus [64] (2011)

Spain

6/09–11/09

Multicentre (13) case series (prospective)/ Hospitalized ≥24 h and had a chest radiograph done

N = 585

71/585 (12.1)

52/585 (8.9)

13/585 (2.2)

545/585 (93.3)

416/585 (71.7)

45/585 (7.7)

28/585 (4.8)

234/585 (40)

CXR non diff

Palacios (2009) [42]

Argentina

6/09–7/09

Random sample specimens

N = 199

19/199 (9.5)

NR

20/199 (10)

96/120 (80)

14/120 (11.7)

152/199 (76.3)

62/199 (31.1)

152//199 (76)

Culture pos

Chitnis [6]

Wisconsin, hospital acute care

PCR + cases

N = 252

59/252 (23.4)

34/59 (58)

Of tho9se cases admitted to ICU

11/252 (4.3)

215/250 (86)

204/249 (81.9)

19/241 (7.9)

NR

123/229 (53.7)

CXR non diff

Riera [65]

13 Hospitals in Spain

N = 585

71/585 (12.1)

52/585 (8.9)

13/585 (2.2)

545/585 (93.1)

202/585 (34.5)

316/585 (54)

45/585 (7.7) (Sputum)

2/585 (0.3)

(1 sputum and 1 antigenuria positive

CXR infil 234/585 (40)

Multilobarl infilt 135/585 (23.1)

Semionov [66]

147 cases with CXR results available in Montreal

N = 147

8/147 (5.4)

6/147 (4.1)

4/147 (2.7)

NR

NR

21/42 (50)

(of 42 radiological positive cases)

5/21 (23.8)

(of 21 positive bacterial cases)

42/147 (28.6)

cases positive CXR

Non diff

To [67]

74 cases in Hong Kong

N = 74

28/74 (37.8)

26/74 (35.1)

2/74 (2.7)

69/74 (93.2)

52/74 (70.3)

9/74 (12.2) bacterial positive

8 sputum

1 blood

0/74 (0)

9/74 (12.2) bacterial positive

8 sputum

1 blood

Diff

Masia [68]

Complicated hospital admitted cases in Spain > 18 years, out patients

N = 100

4/100 (4)

NR

0/100 (0)

NR

NR

14/100 (14)

14/100 (14)

Diff

8 urinary antigen pos, 2 isolated from blood and 4 from sputum

14/100 (14)

Diff

Pecavar [69]

Hospitalized cases

N = 66

7/66 (10.6)

NR

NR

62/64 (96.9)

35/61 (57.4)

5/63 (7.9)

2/63 (3.2)

29/57 (50.9)

CXR Non diff

Liu [70]

One hospital in China

N = 46

NR

NR

NR

46/46 (100)

9/46 (19.6)

9/15 (60)

NR

44/46 (95.6)

CXR or CT scan abnormal

Non diff

Nguyen (2010) [71]

UK

4/09–9/09

Multicentre (55) case series (retrospective)/ Hospitalized cases

N = 631

53/631 (8.4)

NR

- IV = 21/631 (3.3)

29/631 (4.6)

474/631 (75.1)

- NS

366/631 (58)

4/102 (3.9%) of cases with radiological pneumonia

1/102 (0.9) sputum culture

0/102 (0) BC

102/349 (29.2)

- CXR

- No diff

Santa-Olalla Peralta [72] (2010)

Spain

4/09–12/09

National surveillance of severe cases (retrospective) / Hospitalized patients all ages (, in Spain

N = 3025

852/3025 (28.2)

438/3.25 (14.5)

200/3025 (6.6)

2521/2779 (90.7)

- 711/2020 (35.2)

NR

292/957 (30.5, bacteria isolated not reported)

NR

NR

Venkata [73] (2010)

USA

5/09–12/09

Single-centre case series (retrospective)/ Electronic medical records of hospitalized adult patients

N = 66

29/66 (43.9)

23/66 (34.8)

- IV = 17 (73.9)

- NIV = 6 (26.1)

5/66 (7.6)

4 more died after discharge from hospital

60/66 (90.9)

- NR

14/ 29 (48.2)

Bac culture pos

3/29 (10.3), site NS

14/29 (48.2) confirmed and 10/29 (34.5) probable bacterial pneumonia

- NR

- Diff

Jartti [74]

Cases with severe cases and CXR finding available, I hospital in Finland

N = 135

18/135 (13%)

18/135 (13.3)

3/135 (2.2)

NR

NR

5/135 (3.7)

Site not mentioned

1 /135 (0.7)

Isolated from Plural Fluid

84/135 (62.2)

Rizzo [75]

Sentinel sites, Italy

N = 1278

NR

NR

NR

NR

NR

33/1278 (2.6)

0/1278 (0)

271/1278 (21.2)

Non-diff

Kopel [76]

Til Aviv, cases in ICU and PICU

N = 17

17/17 (100)

NR

7/17 (41.2)

NR

NR

9/17 cases (52.9)

(but likely nosocomial infection, so not included)

0/17 (0)

NR

D’Ortenzio [41]

ReUnion Island, all sites, included 785 reported cases, 282 hospitalized cases included here

N = 282

24/282 (8.5)

15/282 (5.3)

7/282 (2.5)

92/171 (53.8)

39/163 (23.9)

(within 48 h)

NR

NR

NR

24/83 (28.9)

(Confirmed and suspected)

Sample not reported

Dominguez-Cherit [77]

Critically ill, hospitalized in 6 hospital in Maxico

N = 58

58/58 (100)

54/58 (93.1)

24/ 58 (41.4)

57/58 (98.3)

52/58 (89.6)

4/58 (6.9)

0/58 (0)

NR