Bacteriaemia

HAIBA case definition for healthcare-associated bacteraemia.

Definition of healthcare-associated bacteraemia

A bacteraemia is defined as at least one blood culture that has tested positive for at least one microorganism classified as pathogenic. See the classification of pathogens below. To qualify as a healthcare-associated bacteraemia, the sampling date needs to fall within a period corresponding to the length of contact with the hospital service, which starts 48 hours after contact and ends 48 hours after contact.

Which department/hospital is the infection attributed to?

Number and incidence are estimated for the departments responsible for the treatment (contact responsibility) and for places of stay (addresses of stay). An infection is attributed to the department responsible for contact 48 hours before the sampling date along with the section (address of stay) where the patient was in the 48 hours leading up to the blood culture being taken. HAIBA shows the infection at the time the blood sample was taken.

When does an infection count as a new infection?

A new case of bacteraemia is counted when there is a new positive blood culture more than 30 days after the first positive blood culture.

How is incidence calculated?

To calculate incidence, the denominator must be defined. For bacteraemia, the denominator is the length of the hospital contact in hours, calculated as the number of days at risk. Hours after a bacteraemia has occurred or after a patient died are not counted in the denominator. Incidence is shown as the number of bacteraemia cases per 10,000 risk days.

Classification of pathogenic and contamination bacteria for healthcare-associated bacteraemia

All culture findings are classified as a “pathogenic microorganism” or “typical contamination bacteria”.

The following are classified as contaminants:

  • Acinetobacter spp, Aerococcus spp (except A. urinae)
  • Bacillus spp (except B. anthracis, B. cereus)
  • Corynebacterium spp (except C. diphtheriae)
  • Lactobacillus spp, Lactococcus spp, Micrococcus spp, Moraxella spp (except M. catarrhalis), Neisseria spp (except N. animaloris, N. canis, N. elongate, N. gonorrhoeae, N. zoodegmatis and N. meningitidis)
  • Propionibacterium acnes
  • Staphylococcus spp (except S. aureus, S. saprophyticus, S. lugdunensis and S. schleiferi)

Most of the departments of clinical microbiology identify Streptococcus spp and non-haemolytic streptococci at species level, particularly if the microorganism is considered the aetiological agent of bacteraemia.
All microorganisms not mentioned above are classified as pathogens in HAIBA.

Material codes for blood cultures

The following codes are used to identify all blood cultures. These are material codes from Mikrobiologisk Diagnose System (MDS). Read more about MDS (in Danish).

Material code and text:

10160 - Blood (blood culture flask)
10166 - Blood from catheter (blood culture bottle)
10165 - Blood from peripheral vein (blood culture bottle)
10167 - Blood from artery (blood culture bottle)
10164 - Blood from umbilical cord (blood culture bottle)
10002 – Whole blood from peripheral vein
10001 - Whole blood
10003 - Whole blood from catheter

Investigation codes

Codes for the requested investigation from the MDS table.

Investigation code and text:

10002 - Aerobic culture (bacteria)
10003 - Aerobic and anaerobic culture (bacteria)
10011 - Culture and resistance
10040 - Anaerobic culture (bacteria)
10045 - Aerobic and anaerobic culture in blood culture bottle
10122 - Staphylococcus aureus (MRSA) (culture)
10190 - Listeria monocytogenes (culture)
10201 - Neisseria meningitidis (meningococci) (culture)
10410 - Actinomyces (culture)
12108 - Tropheryma whipplei DNA/RNA
12127 - Staphylococcus aureus (MRSA) (DNA/RNA and culture)
12200 - Neisseria gonorrhoeae (gonococci) DNA/RNA
17000 – General Bacteriological investigation (=culture) and bacterial DNA/RNA
20001 – Culture (fungi)
20010 – Culture (yeasts)
22025 - Aspergillus DNA/RNA
59015 - Staphylococcus aureus (MRSA), (investigation for)