Microbiology
One virus was isolated in 71.6% of the patients, and 2 viruses in 14.7% of the patients, with RSV present in 78.4% of cases. No more than 2 viruses were isolated in any patient. In 12.7% of cases, no virus was isolated. Among the patients requiring IMV, 1 virus was isolated in 71.4% of patients, and 2 viruses in 21.4% of patients. No virus was isolated in 7.1% of patients. Table 2 shows the virus isolation results from nasal swabs. Infants with parents who smoked had a higher RSV infection rate (87% vs. 76%) compared with those who had not been exposed to tobacco smoke (Figure 2A) .
ETA was performed just after intubation in all the 28 patients requiring IMV. A total of 13/28 (46.4%) intubated patients presented with bacterial isolation in the infection range; in 7/28 (25%), 2 or more bacteria were isolated. In 7/28 (25%) intubated patients, microorganisms in the colonization range were isolated. In 8/28 (28.6%), no other microorganisms were isolated. Of the 8 infants on IMV in whom no microorganisms were isolated, 5 (62.5%) had received previous antibiotic therapy. Table 3 shows the percentage of ETA-isolated microorganisms in patients whose parents smoked and in those whose parents did not smoke.
Blood cultures were positive in 7 (6.9%), and urine cultures in 6 (5.9%) of the patients.