Probiotics for prevention of nosocomial infections: efficacy and adverse effects

PURPOSE OF REVIEW

In this era of increasing antimicrobial resistance, use of probiotics in infection prevention has brought new perspective. However, in 2008 the, until then considered, safe use of probiotics became an important topic after publication of a trial showing excess mortality in patients on probiotic prophylaxis. In this article, we review the concept of infection prevention by probiotics and the present knowledge of the efficacy of probiotics in prevention of infections among patients with abdominal diseases and in intensive care. Safety issues of probiotics will be discussed extensively.

RECENT FINDINGS

Over 30 clinical trials with probiotics to prevent infections have been published, some of which were prematurely stopped recently. Studies with critically ill patients and patients with abdominal diseases showed conflicting results regarding the effects of probiotics on infection rates, as did meta-analyses. These studies are difficult to compare because different probiotics were used which all have different efficacy and safety profiles.

SUMMARY

The efficacy of probiotics in infection prevention among critically ill patients is still not unequivocally determined. The safety profile differs per probiotic strain and should not be generalized towards other strains and patient populations. A well designed and well powered clinical trial with clear endpoints to demonstrate efficacy is warranted.

Positive cultures from cardiopulmonary bypass: prevalence and relevance regarding postoperative infection

OBJECTIVE

Postoperative infections due to cardiopulmonary bypass (CPB) are associated with high morbidity and mortality. The value of positive cultures taken from CPB priming fluid and CPB blood samples, however, is unclear. This study investigates the epidemiology of positive cultures from CPB and their relation to the occurrence of postoperative infection.

METHODS

The study was conducted at the Maastricht University Medical Centre, a 715-bed teaching hospital with 900-1000 surgeries requiring CPB annually. From 1 January 1998 until 31 March 2010, all patients with positive CPB cultures drawn either from priming fluid or blood were retrospectively studied. Second, 335 patients with a positive CPB culture were compared with 335 randomly assigned patients who underwent cardiovascular surgery using CPB and had negative CPB cultures. Patients with active endocarditis were excluded. Demographic data and perioperative parameters were documented. Outcome measures were: a relevant infection (acute infectious valve endocarditis, wound infection, intravascular catheter-related infection, and bloodstream infection), occurrence of fever of unknown origin, and 30-day mortality.

RESULTS

A total of 21840 cultures were analyzed, half being priming fluid and half CPB blood cultures. As many as 111 out of 10920 (1.0%) priming fluid cultures and 598 out of 10920 (5.6%) blood cultures tested positive. Gram-positive cocci predominated both priming fluid and blood cultures. Relevant postoperative infections within 30 days after surgery were seen in 47/663 (7.1%) of patients overall, in 27/330 in the CPB-culture-positive group (8.2%) and 20/333 in the CPB-culture-negative group (6.0%), p=0.275. As many as 38 out of 363 patients (5.7%) were affected by fever of unknown origin (CPB-culture-positive group 4.5%, and CPB-culture-negative 6.9%; p=0.191). The 30-day mortality was 16/330 (4.8%) in the CPB-culture-positive group and 13/333 (3.9%) in the CPB-culture-negative group (p=0.552).

CONCLUSIONS

Positive cultures from both CPB priming fluid and CPB blood samples were not a rarity and mainly involved skin bacteria, arguing that contamination may have played a role. The risk of postoperative infection within 30 days after surgery was not increased in CPB-culture-positive patients. Therefore, no evidence was found to support routine culturing of CPB samples in patients undergoing cardiothoracic surgery.

Clara cell protein in bronchoalveolar lavage fluid: a predictor of ventilator-associated pneumonia?

Introduction

Clara cell protein 10 (CC-10) has been associated with inflammatory and infectious pulmonary diseases. This study evaluates CC-10 concentrations in bronchoalveolar lavage (BAL) fluid as a potential marker of ventilator-associated pneumonia (VAP).

Methods

Between January 2003 and December 2007, BAL fluid samples obtained from critically ill patients at the intensive care unit of the Maastricht University Medical Centre clinically suspected of having VAP were included. Patients were divided into two groups: (1) microbiologically confirmed VAP (the VAP group) and (2) microbiologically unconfirmed VAP (the non-VAP group). The concentration of CC-10 was measured by means of a commercially available enzyme-linked immunosorbent assay kit, and retrospective analysis was performed. Areas under the curve of receiver operating characteristic curves were calculated for CC-10 concentrations.

Results

A total of 196 patients (122 men, 74 women) were included. A total of 79 (40%) of 196 cases of suspected VAP were microbiologically confirmed. The median CC-10 concentration in the VAP group was 3,019 ng/mL (range, 282 to 65,546 ng/mL) versus 2,504 ng/mL (range, 62 to 30,240 ng/mL) in the non-VAP group (P = 0.03). There was no significant difference in CC-10 concentrations between patients treated with or without corticosteroids (P = 0.26) or antibiotic therapy (P = 0.9). The CC-10 concentration did not differ significantly between patients with Gram-positive versus Gram-negative bacteria that caused the VAP (P = 0.06). However, CC-10 concentrations did differ significantly between the late-onset VAP group and the non-VAP group.

Conclusions

The CC-10 concentration in BAL fluid yielded low diagnostic accuracy in confirming the presence of VAP.

Clinical review: post-extubation laryngeal edema and extubation failure in critically ill adult patients

Laryngeal edema is a frequent complication of intubation. It often presents shortly after extubation as post-extubation stridor and results from damage to the mucosa of the larynx. Mucosal damage is caused by pressure and ischemia resulting in an inflammatory response. Laryngeal edema may compromise the airway necessitating reintubation. Several studies show that a positive cuff leak test combined with the presence of risk factors can identify patients with increased risk for laryngeal edema. Meta-analyses show that pre-emptive administration of a multiple-dose regimen of glucocorticosteroids can reduce the incidence of laryngeal edema and subsequent reintubation. If post-extubation edema occurs this may necessitate medical intervention. Parenteral administration of corticosteroids, epinephrine nebulization and inhalation of a helium/oxygen mixture are potentially effective, although this has not been confirmed by randomized controlled trials. The use of non-invasive positive pressure ventilation is not indicated since this will delay reintubation. Reintubation should be considered early after onset of laryngeal edema to adequately secure an airway. Reintubation leads to increased cost, morbidity and mortality.

[Selective decontamination in the ICU: benefit of the doubt]

Since its introduction in 1984, selective decontamination of the digestive tract has had clear supporters and opponents. De Smet et al. conducted a large national study in 13 Dutch intensive care units, investigating the effects of the following 3 regimens on mortality: standard treatment, selective decontamination of the digestive tract and selective oropharyngeal decontamination. The results showed decontamination to have a clear benefit in terms of reducing mortality. Based on these results, decontamination should be used in all intensive care patients.

[Kidney donor with severe disseminated intravascular coagulation: transplantation however successful]

A 41-year-old male, with no previous medical history, was admitted to our intensive care unit with severe isolated neurotrauma and a Glasgow Coma Scale of E1-M1-V1, mid-dilated unreactive pupils and severe abnormalities on the brain CT-scan. A severe syndrome of disseminated intravascular coagulation (DIC) and non-oliguric renal insufficiency developed. Following clinical and neurophysiological examination the patient was declared brain-dead, and the family gave permission for organ donation. The left kidney was transplanted and functioned well immediately. However, in view of the DIC and renal function disorders the right kidney was not considered usable for transplantation elsewhere. Pathological examination revealed many fibrin thrombi in the glomerular capillaries and acute tubular necrosis. This case supports the view that thrombotic microangiopathy in kidneys of patients with DIS, even with renal function impairment, is not an a priori reason for excluding donation.