Peter D. Potgieter

Double-blind study of selective decontamination of the digestive tract in intensive care

Selective decontamination of the digestive tract (SDD), by means of non-absorbable antibiotics, to prevent infection in intensive-care units (ICUs) remains controversial; there is evidence that the regimen reduces the incidence of secondary infection, but no convincing reduction in morbidity or mortality has been shown and the costs and effect on microbial resistance patterns need further study. In a double-blind, placebo-controlled trial, we have tried to find out whether SDD should be used routinely in all ICU patients at high risk of secondary infection. All patients admitted to the ICU who were thought likely to stay in the unit for at least 5 days and to need intubation for longer than 48 h were enrolled and randomly allocated to groups receiving placebo or SDD (amphotericin, colistin, and tobramycin applied to the oropharynx and enterally); all patients received intravenous cefotaxime for 72 h. Of 322 patients randomised, 83 were withdrawn (80 ICU stay or duration of intubation too short, 3 protocol violations). 239 medical, trauma, and surgical patients completed the trial period (114 SDD, 125 placebo). There were no differences between SDD and placebo groups in incidence of infection (30 [26%] vs 43 [34%] patients; p = 0.22), duration of ICU stay (mean 16.2 [14.3] vs 16.8 [12.3] days), hospital stay (29.9 [SD 25.0] vs 31.9 [22.2] days), or mortality (21 [18%] vs 21 [17%]). SDD substantially increased the costs of intensive care. Mechanisms other than bacterial colonisation of the gut may bring about substantial numbers of secondary infections in ICUs. Routine use of SDD in multidisciplinary ICUs cannot be recommended.

Patients' recollection of intensive care unit experience

This study evaluates the recall of 100 patients after ICU admission. There was a wide spectrum of race, religion, occupation, and educational levels. The more common diagnoses included asthma, pneumonia, trauma, and adult respiratory distress syndrome. The average Acute Physiology and Chronic Health Evaluation (APACHE II) score was 12.3, and 68% of the patients were mechanically ventilated. The ICU atmosphere was described as friendly or relaxed by 94% of patients. Confidence in doctors and nurses was good. The most frequently reported unpleasant experiences were arterial blood gas sampling (48% of patients) and tracheal suctioning (30 of 68 ventilated patients). Only 6% of patients disliked ward rounds and discussion around the bedside. This study suggests that arterial lines or pulse oximetry could be used to avoid frequent arterial blood gas analyses and that tracheal suctioning should be performed with greater care. The need for better communication with patients is emphasized.

Long-term effects of selective decontamination on antimicrobial resistance

OBJECTIVE To determine whether selective decontamination of the digestive tract exerts any long-term effects on antimicrobial resistance patterns. DESIGN A surveillance and interventional study comparing the antimicrobial sensitivity patterns of clinically important bacterial isolates the year before a 2-yr, double-blind, randomized, controlled study of selective decontamination of the digestive tract, and for the year thereafter when no use of the regimen was made. SETTING A ten-bed respiratory intensive care unit (ICU) in a 1,200-bed teaching hospital. PATIENTS All 1,528 patients admitted to the ICU over the 4-yr study period were included. There were 406 patients admitted in the year before the study of decontamination of the digestive tract (65% medical, 23% surgical, and 12% trauma), of whom 76% required mechanical ventilation. There were 719 patients admitted during the 2-yr study of selective decontamination (55% medical, 28% surgical, and 17% trauma), of whom 79.6% required mechanical ventilation. There were 403 patients admitted in the subsequent year (61% medical, 25% surgical, and 14% trauma), of whom 76.9% required mechanical ventilation. INTERVENTIONS We performed daily clinical monitoring to detect nosocomial infection, with microbiological investigation when clinically indicated, as well as twice-weekly routine microbiological surveillance sampling. Antimicrobial susceptibility testing using standard laboratory methods was also performed. Selective decontamination of the digestive tract included parenteral cefotaxime and oral and enteral polymyxin E, amphotericin B, and tobramycin. MEASUREMENTS AND MAIN RESULTS The occurrence rate of nosocomial infection was 20.6%, 16.6%, and 25.3%, respectively, in the three study periods. In the year after selective decontamination, there was an increase in the occurrence rate of infection (p = .005), with an-associated increase in infections caused by the Enterobacteriaceae, while a reduction in the level of resistance to the third-generation cephalosporins were found (p = .07). There was a progressive increase in the occurrence rate of infections caused by Acinetobacter species (p = .05). Only 11 infections over the 4 yrs were caused by Enterococcus species. Staphylococcal infections were uncommon (5.7% of admissions), and the level of methicillin resistance did not change. No increase in aminoglycoside resistance occurred. CONCLUSION No long-term effects on antimicrobial resistance or the spectrum of nosocomial pathogens could be attributed to the use of selective decontamination of the digestive tract over a 2-yr period in a respiratory ICU admitting all categories of patients.

Fiberoptic bronchoscopy in the intensive care unit--a prospective study of 147 procedures in 107 patients.

ObjectiveTo determine the value and safety of fiberoptic bronchoscopy in an intensive care unit (ICU). DesignProspective survey. SettingICUs at a tertiary care hospital (except for seven procedures that were performed at a peripheral hospital ICU). PatientsA total of 107 patients with a mean age of 43.9 yrs (range 15 to 84). InterventionsOne hundred forty-seven fiberoptic bronchoscopy procedures (116 performed on patients who were undergoing mechanical ventilation) were performed on 107 patients. Ninety-four procedures were for diagnostic reasons (upper and lower airway inspection, focal and diffuse pulmonary infiltrates), 37 for therapeutic reasons (bronchial toilet, pulmonary hemorrhage, endotracheal intubation), and 16 for both reasons. Topical anaesthesia was used for fiberoptic bronchoscopy; sedation was rarely needed. Appropriate diagnostic and therapeutic procedures were performed. Measurements and Main ResultsOxygen saturation, electrocardiogram, and blood pressure were monitored. Transbronchial biopsies (all on mechanical ventilation) for diffuse pulmonary infiltrates were diagnostic in five of seven cases, and were suggestive of the diagnosis in a further case. Endobronchial biopsies were not diagnostic in any of three cases. Bronchial brushings for microbiology were positive in nine of 50 procedures and for cytology in one of nine procedures. Protected specimen brushes for pulmonary infiltrates gave positive microbiology findings in five of 23 procedures. In pulmonary hemorrhage, focal bleeding was found in five cases, diffuse bleeding in four, and no bleeding source in three. In lobar atelectasis, bronchial toilet led to full reexpansion (n = 20 procedures), partial reexpansion (n = 5), and no change (n = 3). Intubation with fiberoptic bronchoscopy was successful in four of five patients. Hypoxemia (oxygen saturation <90%) occurred in 29 procedures; it caused no problems. Complications included hemorrhage (n = 2), supraventricular tachycardia (n = 1), pneumothorax (n = 1), pneumatocele (n = 1), and bronchospasm (n = 1). No deaths were attributable to fiberoptic bronchoscopy. ConclusionsFiberoptic bronchoscopy in the ICU is safe, contributes valuable diagnostic information, and is useful for therapeutic purposes. (Crit Care Med 1994; 22:259–264)

Nosocomial infections in a respiratory intensive care unit.

A total of 250 consecutive admissions to an open-plan respiratory ICU were analyzed prospectively to identify the incidence of secondary hospital-acquired infections and possible predisposing factors. Despite preventative measures and a restricted antibiotic policy, 23.6% of patients developed secondary infections. Patients admitted after multiple trauma were the only diagnostic category of patients who showed a significantly increased incidence of secondary infections. The length of hospitalization and number of patients who had intubations or tracheostomies was higher in the group with secondary infection; the causal relationship was difficult to establish. Patients who were not intubated or tracheostomized did not develop secondary infection. Prior administration of antibiotics did not appear to influence the incidence of secondary infection. There was a significant increase in secondary infections in patients with a higher therapeutic intervention scoring system score. The predominant pathogens cultured were highly resistant Gram-negative organisms, particularly Acinetobacter sp. and Pseudomonas sp. Staphylococcus aureus was the most common Gram-positive pathogen. The ICU course was probably prolonged by the complication of nosocomial infection, which may have contributed to the deaths.

Selective decontamination of the digestive tract in multiple trauma patients--is there a role? Results of a prospective, double-blind, randomized trial.

Objective: To evaluate the efficacy of the technique of selective decontamination of the digestive tract in preventing the development of secondary infection and its influence on morbidity and mortality rates in multiple trauma patients with chest injuries requiring intermittent positive‐pressure ventilation. Design: Prospective, double‐blind, randomized study. Setting: A multidisciplinary respiratory intensive care unit (ICU) in a 1,500‐bed teaching hospital. Patients: Seventy‐two patients (mean Injury Severity Score of 29.5) who were intubated for >48 hrs and remained in the ICU for >5 days. Interventions: Patients were randomized on admission to receive selective decontamination therapy or placebo. All patients received intravenous cefotaxime for 72 hrs and the treatment group received oral and enteral selective decontamination with amphotericin B, polymyxin E, and tobramycin (n = 39), while the placebo group received a placebo containing oral paste and enteral solution (n = 33). Measurements: Secondary infection was determined clinically and microbiologically and surveillance cultures were monitored for gastrointestinal colonization. Results: The patient groups were fully comparable for age, severity of illness, and compromising factors. There was no difference in the number of patients infected (11 treatment group vs. 11 placebo), infections (17 vs. 16) and deaths (5 vs. 3); the duration of ICU (15.5 vs. 14.2 days) and hospital stays (26.3 vs. 25.5) were also similar. Microbiological surveillance cultures confirmed effective elimination of aerobic Gram‐negative bacilli, and infections in the treatment group were largely due to Staphylococcus aureus and Staphylococcus epidermidis. Conclusion: We have been unable to show any benefit from the use of selective decontamination of the digestive tract in the prevention of secondary infections in multiple trauma patients. (Crit Care Med 1994; 22:33‐39)

Influence of amikacin as the primary aminoglycoside on bacterial isolates in the intensive care unit

Amikacin was introduced as the primary aminoglycoside in our hospital to prevent the further development of multiply resistant Gram-negative organisms. This study compares clinical and microbiological data before and after institution of this policy to evaluate the influence on clinical outcome in patients as well as changing resistance patterns in the respiratory ICU. Patient populations were similar in terms of severity of illness (Acute Physiology and Chronic Health Evaluation II scores), age, ventilation, invasive procedures, and the incidence of various diseases. We found that the rate of amikacin resistance increased from 8.5% to 39.6% with an increase in resistance to tobramycin (19.3% to 33.3%) and netilmicin (23.9% to 47.9%) over the same period despite minimal usage of these drugs. The clinical outcome was similar in the periods contrasted. Our findings suggest that restricting aminoglycosides to amikacin only resulted in increasing Gram-negative resistance although there was no significant effect on patient outcome.

Intensive care management of community-acquired Klebsiella pneumoniae

The clinical features of 18 patients with Klebsiella pneumoniae requiring intensive care unit (ICU) management are presented. All patients required ventilatory support; 17 were given constant positive pressure ventilation and 10 required greater than 10 cm positive end expiratory pressure. The clinical picture was characteristic: pre-existing medical disease, clinical features of severe pneumonia and copious purulent bronchial secretions, Gram--ve organisms on Grams stain and lobar consolidation on the chest radiograph were common. Septicaemic shock, confusion and uncompensated metabolic acidosis were the presenting clinical features predicting a poor outcome. Antimicrobial chemotherapy, that combined an aminoglycoside and a third generation cephalosporin to ensure adequate early antibiotic serum levels, may help to improve the prognosis.

Prophylactic Use of the New Quinolones for Prevention of Nosocomial Infection in the Intensive Care Unit

SummaryThe new quinolone antimicrobial agents, particularly those with less activity against anaerobes, selectively prevent colonisation of the alimentary tract by Gram-negative bacilli and staphylococci without substantially affecting the normal anaerobic flora, which preserve the colonisation resistance of the gut. These properties ideally position this class of antibacterial agent for selective decontamination of the digestive tract (SDD) in the prevention of nosocomial infection. The rationale for this procedure is based on the presumption that a significant proportion of infections in compromised patients are endogenous in origin, arising from the host’s own microbial flora. If this colonisation by potentially pathogenic microflora within the normal flora can be significantly reduced without being replaced by other more pathogenic microorganisms, the risk of endogenous infection should be minimised.The quinolones have proved to be ideal agents for use in preventing infection in bone marrow transplant and other neutropenic patients. They have been used for SDD in the general intensive care unit population, although the technique has not received widespread acceptance. There have been only 4 reported randomised studies using quinolones as part of SDD regimens and only 301 patients have been evaluated. Although the incidence of ventilator-associated pneumonia has been significantly reduced from 36 to 15%, no effect has been shown on mortality. The cost of using SDD is significantly less with the quinolones than with other regimens, and induction of resistance has not been noted.The new quinolones, and in particular the more recently developed agents with extended Gram-positive activity, appear to be ideally suited for SDD, and their careful evaluation in further large, well designed trials is warranted.

Current Disease Management Strategies in the Treatment of Serious Infections

SummaryThe diagnosis of severe infection, selection of an appropriate antibiotic to which the most likely pathogens are sensitive, its prompt administration at a sufficient dosage and adequate supportive therapy are critical to ensuring a favourable patient outcome. However, the progressive emergence of strains of microorganisms multiresistant to routinely used antibiotics is causing growing concern and increasing the difficulty of reliably achieving these goals, particularly when these organisms cause serious infections. Resistance is particularly common among organisms such as Pseudomonas aeruginosa and the staphylococci, and is increasingly being encountered in streptococci, enterococci, and Gram-negative bacilli such as Acinetobacter spp., Citrobacter freundii and Serratia spp. Resistance is more likely to appear when such pathogens are exposed to antibiotic concentrations at, above, or slightly below the minimum inhibitory concentration, which may result from inadequate dosages, administration via an inappropriate route, or the presence of bacteria in sequestered sites.The new extended spectrum fluoroquinolones such as clinafloxacin have significantly more activity against fluoroquinolone-resistant strains than ciprofloxacin, ofloxacin or fleroxacin, while retaining the properties that have made the fluoroquinolones such an attractive class of antibacterials over the past decade. However, there has been a rapid emergence of resistance to newer agents such as ciprofloxacin, which may be partly attributable to their repetitive use and to precursors such as nalidixic acid. Most resistance has occurred among hospitalised patients and seems to be due to cross-infection by a single resistant clone; this raises the possibility that, if used appropriately, clinafloxacin may not lose its advantage in helping to treat serious, multiresistant pathogens as rapidly as other antibacterials.