[Gastric colonization and its effect on pathogenesis of nosocomial pneumonia].
OBJECTIVE
To study the gastric colonization and its effect on development of nosocomial pneumonia (NP).


METHODS
We investigated the microorganism (mainly pathogens) constitution, isolating sequences and risk factors in gastric, oropharyngeal and lower respiratory tract flora. Microbiologic cultures of serially taken samples of gastric aspirates, oropharyngeal swabs and bronchoalveolar lavages (BALs) or sputums were performed at the time of ICU admission and subsequently every morning in 52 surgical patients with nasogastric tube. Etiologic diagnosis of NP was based on quantitative cultured of BAL or sputum. Sequences of colonization were examined by comparing isolates of the same species with concordance of minimum inhibitory concentration values to 12 antibiotics.


RESULTS
A total of 237 pairs of gastric and oropharyngeal specimens were taken. 77 strains of gram- negative bacilli (GNB) isolated from stomach, more than the number of GNB isolated from oropharynx (51 strains), P = 0.007. Comparing the species, Enterobacteriaceae isolated from stomach was much more than that from oropharynx (46 vs 24 strains, P = 0.004), and in most instances stomach colonization was before oropharynx colonization one to two days. Isolating rates of Pseudomonas were the same in both kinds of specimens. On contrast, Acinetobacter colonization in oropharynx was much more than that in stomach (10 vs 3 strains, P = 0.049). Risk factors for GNB colonization in stomach included increased gastric pH, medications inhibiting gastric acid secretion (such as cimitidine, omeprazole), and systemic use of cephalosporins. 10 patients developed NP and 5GNB (Enterobacter cloacae 2, Pseudomonas aeruginosa 2, Acinetobacter anitratum 1) isolated from BAL or sputum in 4 of 10 patients. A sequence of colonization from the stomach to the respiratory tract leading to pneumonia was observed in 3 patients.


CONCLUSIONS
It was suggested that the stomach is likely to be an important source of pathogens leading to NP, especially Enterobacteriaceae pneumonia.
Ma
J
J
Department of Medicine, Hudong Hospital, Shanghai 200129.
Hu
B
B
He
L
L
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000302:isolation & purification*; D003428:Cross Infection / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010614:Pharynx / Q000382:microbiology; D018410:Pneumonia, Bacterial / Q000209:etiology*; D013270:Stomach / Q000382:microbiology*