Table 3.

Relationship between clinical cultures and surveillance cultures in LOS acquired during NICU stay (nosocomial infections)

LOS episodes acquired during NICU stay	Surveillance culture positive	Surveillance culture negative
Clinical culture positive (9)	7	2
Clinical culture negative (24)	15	9
Total (33)	22	11

Clinical cultures—cultures done on suspicion of infection

Surveillance cultures—cultures done on admission from anterior nares, umbilical swabs, respiratory secretions and rectal swabs and weekly during the NICU stay from respiratory secretions and rectal swabs

Surveillance culture positive—with regard to culture positive infection episodes, if we have isolated the same organism in a surveillance sample beforehand or with regard to culture negative infection episodes, if we have isolated a possible pathogenic organism as a colonizer in any surveillance sample

Surveillance culture negative—with regard to culture positive infection episodes, if we have not isolated the same organism or isolated a different organism in any of the surveillance samples beforehand. With regard to culture negative infection episodes, if we have not isolated any possible pathogenic organism as a colonizer they were also considered as screening negative occasions