The course of nosocomial oropharyngeal colonization in patients recovering from acute respiratory failure

The Effect of Blind-Protected Specimen Brush Sampling on Antibiotic Use in Patients with Suspected Ventilator-Associated Pneumonia

The diagnosis of pneumonia in ventilated patients is exceedingly difficult. Although culture of tracheal aspirates have poor diagnostic value they are frequently used to diagnose ventilator-associated pneumonia (VAP). Recently a number of studies have reported on the diagnostic value of “blind” protected specimen brush (B-PSB) sampling in the diagnosis of VAP. B-PSB sampling can readily and safely be performed by respiratory care practitioners (RCPs). The aim of this study was to determine the cost-effectiveness of B-PSB sampling performed by respiratory therapists in patients with suspected VAP. During a 3-month run-in period, patients in our medical intensive care unit (MICU) with suspected VAP were treated based on clinical criteria and tracheal aspirate culture. Following this run-in period the house staff, nurses, and RCPs were prevented from sending tracheal aspirates for culture. All patients suspected of having VAP underwent B-PSB sampling with quantitative culture. The B-PSB sampling was performed by RCPs who had been trained to perform the technique. A PSB with a potential bacterial pathogen concentration greater than 500 CFU/ml was regarded as positive. During the 3-month run-in period 172 patients received mechanical ventilation with an average of 4.9 ±3.1 ventilator days/patient. During this period 79 patients were treated for VAP. During the 3-month study period 160 patients received mechanical ventilation, with an average of 5.1 ± 2.9 ventilator days/patient (NS). Fifty-eight B-PSB samplings were performed in 50 patients for suspected VAP. No complications related to the procedure were reported. No tracheal aspirates were cultured during this time period. Eight patients had positive PSB cultures. Antibiotics were changed in three of these patients based on the PSB results. Thirty-eight courses of antibiotics (in 36 patients) were stopped based on negative PSB results. Twelve cases of VAP were suspected in six patients receiving antibiotics for other reasons. No change in antibiotics were made in these cases based on the negative PSB results. The length of mechanical ventilation was 5.4 ± 3.2 days in the 38 culture-negative patients in whom antibiotics were stopped compared to 8.2 ± 4.7 days in the 8 patients with PSB-positive VAP (NS; p = 0.14). The direct cost savings as a result of discontinuing antibiotics was $9,500. There were additional cost savings due to the reduced number of culture specimens sent to the laboratory (approximately $3,000; taking the $23 cost of the PSB brush into account), with a projected annual cost savings of $50,000. B-PSB sampling is a simple and cost-efficient diagnostic test that can safely be performed by adequately trained RCPs. Furthermore, this study confirms that antibiotics may be safely discontinued in patients with negative quantitative culture results.

Oropharyngeal carriage and lower airway colonisation/infection in 45 tracheotomised children

BACKGROUND

A study was undertaken to determine the oropharyngeal carrier state of potentially pathogenic microorganisms (PPM) and the magnitude of colonisation and infection rates of the lower airways with these PPM in children requiring long term ventilation first transtracheally and afterwards via a tracheotomy.

METHODS

A 5 year, prospective, observational cohort study was undertaken in 45 children (33 boys) of median age 6.4 months (range 0-180) over a 5 year period at the Royal Liverpool Children's NHS Trust of Alder Hey, a university affiliated tertiary referral centre. The children were first admitted to the 20-bed paediatric intensive care unit (PICU) and, following placement of a tracheotomy, they were transferred to a four bedded respiratory ward. The two main indications were neurological disorders and airway obstruction. All children were ventilated transtracheally for a median period of 12 days (range 0-103) and, after placement of the tracheotomy, for a similar period of 12 days (range 1-281). Surveillance cultures of the oropharynx were taken on admission to the PICU and on the day of placement of the tracheotomy. Throat swabs were taken twice weekly during ventilation, both transtracheal and via the tracheotomy. Tracheal aspirates were taken once weekly and when clinically indicated (in cases where the lower airway secretions were turbid).

RESULTS

Twenty five patients (55%) had abnormal flora, mainly aerobic Gram negative bacilli (AGNB), particularly Pseudomonas aeruginosa, while the community PPM Staphylococcus aureus was present in the oropharynx of 37% (17/45) of the study population. The lower airways were sterile in six children; the other 39 patients (87%) had a total of 82 episodes of colonisation. "Community" PPM significantly increased once the patients received a tracheotomy, independent of the number of patients enrolled, episodes of colonisation/infection, and the number of colonised/infected patients. "Hospital" PPM significantly decreased after tracheotomy only when episodes were compared.

CONCLUSIONS

While P aeruginosa present in the admission flora caused primary endogenous colonisation/infection during mechanical ventilation on the PICU, S aureus not carried in the throat was responsible for the exogenous colonisation/infection once the patients had a tracheotomy. This is in sharp contrast to adult studies where exogenous infections are invariably caused by AGNB. This discrepancy may be explained by chronic underlying conditions such as diabetes, alcoholism, and chronic obstructive pulmonary disease which promote AGNB, whereas the children were recovering following tracheotomy.

New developments in total parenteral nutrition for children

The field of parenteral nutrition continues to evolve along two major paths: prevention of complications and refining of nutritional needs. Parenteral nutrition-associated liver disease remains a vexing problem. No single factor is to blame; rather, it requires a number of "hits." In the infant, the liver disease primarily appears to be related to prematurity of bile flow and production, infection, lack of enteral feedings, and most recently appreciated, perhaps free radicals. We are able to meet the nutritional needs of our patients, but our knowledge of actual nutritional requirements remains incomplete. Future studies need to define better appropriate intakes and to rigorously test the utility of proposed nutrients such as glutamine.

Clinical impact of abnormal gut flora in infants receiving parenteral nutrition

OBJECTIVE

Illness is associated with the carriage of abnormal flora (aerobic Gram-bacilli except E. coli) in the oropharynx and rectum. The aim of this study was to investigate whether carriage of abnormal flora is associated with increased risk of sepsis and septicemia in surgical newborn infants.

METHODS

A 2-year prospective study was carried out on 94 consecutive newborn infants requiring parenteral nutrition (PN) for gastrointestinal abnormalities. Throat and rectal swabs were taken on day 1 of PN and twice weekly. Patients were divided into two groups: abnormal flora (AF; n = 41) and normal flora (NF; n = 53). Sepsis was defined as clinical features of generalized inflammation requiring blood culture. Septicemia was the combination of sepsis and positive blood culture.

RESULTS

Among the infants carrying abnormal flora Pseudomonas and Enterobacter spp. predominated. Duration of PN (AF median 30 days; NF median 9 days), incidence of sepsis (AF 29%; NF 6%), and septicemia (AF 22%; NF 2%) were significantly greater in the group of infants with abnormal flora. Surveillance cultures allow the detection of a subset of infants on PN at high risk of sepsis and septicemia. The degree of gut dysfunction related to the severity of underlying disease determines the duration of PN and the development of abnormal flora. The association between abnormal carriage and increased risk of sepsis and septicemia may be because of the intestinal endotoxin pool known to cause liver impairment and consequent suppression of systemic immunity.