[Routine throat swabs in artificially ventilated patients: meaningful bacteriologic monitoring or a needless...

Organisms colonizing the oropharynx of patients in the intensive care unit (ICU) play an important role in the development of nosocomial infection. Thus, routine throat swab specimens of ICU patients are recommended to screen for potential pathogens [20]. This investigation was designed to clarify the value of throat swabs taken in addition to tracheal aspirates, urine cultures, and wound swabs with regard to antibiotic therapy in patients with pneumonia and other infections. MATERIALS AND METHODS. A total 627 intubated patients were examined in a surgical ICU during a 12 month period. Pharyngeal swabs, tracheal aspirates, urine cultures, and-if necessary-swabs from wounds and drains were taken immediately after admission to the ICU and routinely thereafter three times each week.

Early onset pneumonia: pneumonia occurring within 4 days; late onset pneumonia: pneumonia occurring after the 4th day. Intra-abdominal infection: diffuse or localized peritonitis or abdominal abscess. Wound infection: soft-tissue or bone infection. Corresponding organisms: the same species of bacteria with the same sensitivity pattern (Table 1). RESULTS. Sixty-eight of the patients developed pneumonia. 37 had early onset pneumonia. In 22 of these patients, throat and tracheal specimens had been obtained 2-3 days before the pneumonia was diagnosed. In these specimens, the causative organisms for the subsequent pneumonia were isolated in the throat in 60% of cases and in tracheal secretions in 40% (Table 3). In 35 patients with late onset pneumonia, the causative bacteria were found in 66% of the cases in the throat swabs obtained 2-3 days before the diagnosis was made, in tracheal aspirates in 74% (Table 4). Throat swabs obtained at admission to the ICU from already infected patients or from patients who developed an infection were significantly more colonized with potentially pathogenic micro-organisms (Fig. 1). In 4 patients with early onset pneumonia the results of the throat swab cultures influenced antibiotic therapy, but none of the throat culture results influenced the therapy of the patients with late onset pneumonia or other infections (intra-abdominal infection, wound infection, urinary tract infection). CONCLUSIONS. The throat swab taken at admission may indicate patients at risk for infection. However, throat cultures taken routinely thereafter, parallel with tracheal aspirate cultures, do not provide additional information that is diagnostically or therapeutically helpful. Therefore, throat swab cultures are not necessary for routine bacteriological monitoring. For the prevention of colonization by local administration of antimicrobial agents, regular throat cultures are mandatory.