Oropharyngeal or Gastric Colonization and Nosocomial Pneumonia in Adult Intensive Care Unit Patients

Abstract

Colonization of the digestive tract has been supposed to be the source of many hospital-acquired infections, especially nosocomial pneumonia. To assess the relationship between oropharyngeal and gastric colonization and subsequent occurrence of nosocomial pneumonia, we prospectively studied 86 ventilated, intensive care unit (ICU) patients. Oropharyngeal or gastric colonizations were detected and quantified on admission and twice weekly during ICU stay. When nosocomial pneumonia was suspected on clinical grounds (new chest X-ray infiltrate and purulent tracheal secretions), diagnosis was assessed on fiberoptic bronchoscopy with quantitative cultures of a protected specimen brush sampling and/or a plugged telescoping catheter sampling yielding > or = 10(3) cfu/ml of at least one microorganism. Bacterial strains responsible for colonization and infection (Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacteriaceae, and Staphylococcus aureus) were compared using pulsed-field electrophoresis. A total of 31 cases (36%) of pneumonia were diagnosed. Oropharyngeal colonization, detected either on admission or from subsequent samples, was a predominant factor of nosocomial pneumonia as compared with gastric colonization. For instance, oropharyngeal colonization with A. baumannii yielded a 7.45-fold estimated increased risk of pneumonia as compared with patients not yet or not identically colonized (p = 0.0004). DNA genomic analysis demonstrated that an identical strain was isolated from oropharyngeal or gastric samples and bronchial samples in all but three cases of pneumonia, due to S. aureus. These findings provide better knowledge of the pathophysiology of nosocomial pneumonia in mechanically ventilated patients.

Colonização e translocação bacteriana orofaríngea, gástrica e traqueal em crianças submetidas à ventilação pulmonar mecânica

“…Microorganisms responsible for the occurrence of pneumonia in adult patients submitted to intensive therapy have been commonly identified, primarily in the oropharyngeal region. (8,9) In a similar matter, a study conducted in a Brazilian PICU revealed that around 41.8% of the 55 studied children presented potentially pathogenic species of microorganisms colonizing the oropharynx at the time of admission to the unit. (10) All the children included in this study presented oropharyngeal colonization within the first 24 hours of tracheal intubation, either by bacteria of the normal oropharyngeal microbiota or by potentially pathogenic bacteria, whereas gastric colonization in this period was identified in 14 of the 30 children.…”

“…(16) There was also predominance of pathogenic bacteria such as Enterobacter spp, K. pneumoniae and P. aeruginosa, in the cultures of oropharyngeal and tracheal secretions, a result similar to that found in other studies that demonstrated that colonization of the oropharynx by gram-negative pathogens is an almost universal occurrence in critical patients submitted to MPV. (8,13,17) Risk factors for the development of pneumonia may be divided into three categories: those related to the host, equipment and devices, and to the professionals. Host-related risk factors include: pre-existent conditions such as immunosuppression and chronic diseases, acute respiratory diseases, position in the bed, level of consciousness, number of tracheal intubations, and use of medications such as antibiotics and sedative.…”

Relationship between antibiotic consumption, oropharyngeal colonization, and ventilator-associated pneumonia by Staphylococcus aureus in an intensive care unit of a Brazilian teaching hospital

“…On the other hand, there is less information on the etiopathogenesis for the development of VAP by ORSA. DNA genomic analysis demonstrated that an identical strain was isolated from oropharyngeal or gastric samples and bronchial samples in all but three cases of pneumonia, due to S. aureus 30,31 . In our study 5.5% of patients colonized by S. aureus developed VAP as opposed to just 1.8% of patients not colonized (p > 0.05), and among individuals colonized by phenotypes ORSA and OSSA, 5% and 6.5% developed VAP, respectively, as opposed to just 0% and 1.3% (p = 0.003/p = 0.05) of patients not colonized for these phenotypes, respectively.…”

Ventilator‐associated pneumoniaDiagnosis, pathogenesis and prevention

“…In health, the oropharynx is colonised predominantly by nonpathogenic bacteria, but in hospitalised patients, this flora is replaced with pathogenic bacteria, predominantly aerobic GNB and staphylococci, and this increases the risk of VAP [41]. Prolonged exposure of the epithelial surface to the bacterial adhesin molecules and the changes in host epithelial cell receptors in critical illness promote this abnormal colonisation.…”