Relative Frequency of Nosocomial Pathogens at a University Hospital by Service from 1980 to 2008

Background: Knowledge of the relative frequency of nosocomial pathogens by service is very useful for clinicians in selection of empirical therapy for healthcare-associated infections. Although many studies have reported the relative frequency of nosocomial pathogens by service, the information has been limited to type of ICU. Examining the relative frequency of pathogens by major service and by location within or outside an ICU provides important information for clinical decisions.

Objective: To review the relative frequencies of nosocomial pathogens isolated by service at a university hospital by site from 1980-2008: ICU vs non-ICU; medicine vs surgery vs pediatrics.

Methods: Data were collected through hospital-wide surveillance at the University of North Carolina Health Care, a 757 bed teaching facility. To analyze 29 years of data, 6 5-year blocks were created and categorized to medicine, surgery, pediatrics based on service and nurse station codes. Using SAS, 6 5-year blocks of relative frequency of isolated nosocomial pathogens were compared by X² analysis and trends for each pathogen were estimated by regression analysis.

Results: Overall, at least one pathogen was isolated from 35,510 (85.2%) of the 41,660 nosocomial infections.

Slope Estimate

Total (1980-2008)

Medicine

Surgery

Pediatrics

Organism

Rank

N

%

overall

ICU

Non- ICU

overall

ICU

Non- ICU

overall

ICU

Non-ICU

S. aureus

1

5483

15.4

0.071‡

-0.018

0.087†

0.133†

0.003

0.211†

-0.136†

-0.174†

-0.119‡

E. coli

2

3753

10.6

-0.100†

0.089¶

-0.075‡

-0.077†

-0.005

-0.084†

-0.056

0.078

-0.112§

CoNS

3

3587

10.1

0.155†

0.078

0.173†

0.116†

0.138†

0.106†

0.008

-0.021

0.029

Candida/yeast

4

3494

9.8

0.060‡

-0.126¶

0.216†

-0.003

-0.081‡

0.069‡

0.070¶

-0.033

0.259†

Enterococcus spp

5

3138

8.8

0.212†

0.207‡

-0.010

0.048§

0.029

-0.028

0.156†

0.068

0.037

P. aeruginosa

6

2954

8.3

-0.153†

-0.208¶

-0.171†

-0.075†

-0.160†

-0.090†

0.075¶

0.247†

0.193‡

Klebsiella spp

7

2186

6.2

-0.171†

-0.081

-0.147†

-0.059§

0.016

-0.058¶

-0.007

0.028

-0.081

Enterobacter spp

8

2097

5.9

-0.199†

-0.146¶

-0.182†

-0.125†

-0.069¶

-0.126†

0.172†

0.088

0.067

Other streptococci

9

1252

3.5

-0.115‡

-0.362§

-0.083¶

-0.095†

-0.096¶

-0.061¶

-0.157‡

0.282‡

-0.013

Other anaerobes

10

1044

2.9

0.180†

-0.210¶

0.214†

-0.020

-0.126§

0.011

0.145¶

-0.298†

0.289‡

† p≤0.0001, ‡ p≤0.001, § p≤0.01, ¶ p≤0.05, only data for top 10 pathogens displayed, all data will be presented.

Conclusions: Overall, S. aureus showed significant increasing trend in medicine and surgical service but significant decreasing trend in pediatrics. In medicine and surgical services, E. coli, P. aeruginosa, Klebsiella, Enterobacter, and other streptococci have significantly decreased whereas CoNS have significantly increased. Candida showed increasing trend in medicine and pediatrics service. Enterococcus showed increasing trend for all services.