J. Dankert

Effects of selective decontamination of digestive tract on mortality and acquisition of resistant bacteria in intensive care: a randomised controlled trial

BACKGROUND Selective decontamination of the digestive tract (SDD) is an infection-prevention regimen used in critically ill patients. We assessed the effects of SDD on intensive-care-unit (ICU) and hospital mortality, and on the acquisition of resistant bacteria in adult patients admitted to intensive care. METHODS We did a prospective, controlled, randomised, unblinded clinical trial. 934 patients admitted to a surgical and medical ICU were randomly assigned oral and enteral polymyxin E, tobramycin, and amphotericin B combined with an initial 4-day course of intravenous cefotaxime (SDD group n=466), or standard treatment (controls n=468). Primary endpoints were ICU and hospital mortality and the acquisition of resistant bacteria. FINDINGS In the SDD group 69 (15%) patients died in the ICU compared with 107 (23%) in the control group (p=0.002). Hospital mortality was lower in the SDD groups than in the control group (113 [24%] vs 146 [31%], p=0.02). During their stay in intensive care, colonisation with gram-negative bacteria resistant to ceftazidime, ciprofloxacin, imipenem, polymyxin E, or tobramycin occurred in 61 (16%) of 378 SDD patients and in 104 (26%) of 395 patients in the control group (p=0.001). Colonisation with vancomycin-resistant enterococcus occurred in five (1%) SDD patients and in four (1%) controls (p=1.0). No patient in either group was colonised with meticillin-resistant Staphylococcus aureus. INTERPRETATION In a setting with low prevalence of vancomycin-resistant enterococcus and meticillin-resistant S aureus, SDD can decrease ICU and hospital mortality and colonisation with resistant gram-negative aerobic bacteria.

The intestinal mucus layer from patients with inflammatory bowel disease harbors high numbers of bacteria compared with controls.

BACKGROUND & AIMS Whether the bacterial flora contributes to the pathogenesis of inflammatory bowel disease (IBD) by increased penetration in mucus, increased adherence to epithelial cells, or invasion of the epithelium is unknown. We therefore studied the spatial distribution of bacteria in the mucosa of rectal biopsy specimens from patients with IBD and from controls. METHODS Rectal biopsy specimens from 19 patients with IBD and from 14 controls were studied by using nonradioactive ribosomal RNA in situ hybridization. Total mucosal surface length examined for each patient was measured, and the number of bacteria visualized was estimated semiquantitatively. RESULTS No bacteria were observed in biopsy specimens from 10 controls (71%) and 6 IBD patients (32%) (P = 0.04; odds ratio, 5.42; 95% confidence interval, 1.23-23.9). IBD rectal specimens contained significantly more bacteria than control samples (P = 0.004). Bacteria were localized within the mucus layer but did not adhere to the epithelial cells and were not present within the lamina propria. There was no correlation between the numbers of bacteria present and either the degree of inflammation or the use of anti-inflammatory agents or sulfasalazine compounds. CONCLUSIONS The intestinal mucus in IBD patients is less protective against the endogenous microflora than in controls, resulting in increased association of luminal bacteria with the mucus layer.

Cross-linking and characterisation of gelatin matrices for biomedical applications.

Cross-linking of gelatin A and B with N,N-(3-dimethylaminopropyl)-N′-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was optimised by varying the NHS/ EDC molar ratio at constant EDC concentration. Native and cross-linked gelatin gels were characterised using the degree of swelling, the number of free amine groups, the phase transition temperature, and titration of the carboxylic acid residues. The cross-linking reaction was most efficient at a NHS to EDC molar ratio of 0.2. At higher NHS/EDC molar ratios, the reaction of EDC with NHS becomes more pronounced, thereby reducing the effective amount of EDC for cross-linking. Swelling measurements of cross-linked gelatin gels gave deviating results when no NHS was used, which was explained by heterogeneous localisation of cross-links in the gelatin gel. The incorporation of undesired compounds into the gelatin gels during the cross-linking reaction was not observed. At optimal NHS to EDC molar ratio, gelatin A and B were cross-linked using increasing EDC/COOHgelatin molar ratios. A range of samples varying from very low cross-link density to very high cross-link density (at high EDC/COOHgelatin) was obtained. Stability of the gels is enhanced with increasing cross-link density, but a minimal cross-link density is required to obtain gelatin gels which are stable at 40°C.

Effect of Helicobacter pylori eradication on gastritis in relation to cagA: A prospective 1-year follow-up study

BACKGROUND & AIMS Whether Helicobacter pylori eradication resolves intestinal metaplasia and atrophy and whether infection with cagA+ H. pylori is related to a specific clinical outcome are not known. The aim of this study was to investigate the role of H. pylori eradication on the course of intestinal metaplasia (IM) and atrophy in relation to cagA. METHODS In a large prospective study, the cagA status of H. pylori isolated from consecutive dyspeptic patients was related to clinical outcome before and 1 year after successful eradication of H. pylori. At pretreatment and 4-6 weeks and on average 1 year after eradication therapy, the degree of gastritis and the status of H. pylori were assessed by culture and histopathology. RESULTS Specimens of cagA+ H. pylori were recovered from 122 of 155 (79%) patients infected with H. pylori. Pretreatment degrees of gastritis activity, superficial epithelial damage, IM, and atrophy were significantly greater in patients infected with cagA+ H. pylori (P < 0.001). After successful eradication of H. pylori, a significant improvement of activity of gastritis and superficial epithelial damage occurred (P < 0.001), but the degree of IM and atrophy did not change, irrespective of the cagA status. CONCLUSIONS The usefulness of H. pylori eradication to revert precancerous lesions such as IM and atrophy after 1-year follow-up is questionable.

Diagnosis of intestinal and disseminated microsporidial infections in patients with HIV by a new rapid fluorescence technique.

AIMS--To assess the value of a new rapid fluorescence method for the diagnosis of microsporidiosis in HIV seropositive patients. METHODS--Microsporidian spores in stools were demonstrated by using the fluorochrome stain Uvitex 2B. The new technique was evaluated in three groups of HIV seropositive patients with diarrhoea. Group 1: 19 patients with biopsy confirmed E bieneusi infection (186 stool samples); group 2: 143 consecutive patients from whom faeces were submitted for routine investigation of diarrhoea (318 samples); group 3: 16 patients with small intestinal biopsy specimens negative for microsporidia (55 samples). The new method was used to monitor spore shedding during experimental treatment with paromomycin and albendazole in four patients. RESULTS--Brightly fluorescent spores were detected in all stool samples of patients in group 1. In group 2 16 (11%) patients had spores in their stool samples. E bieneusi was found in 11 patients; in the other five another genus of microsporidia, Encephalitozoon, was recognised. Encephalitozoon spores were also found in the urine of three of these patients and in the maxillary sinus aspirate of two of them, suggesting disseminated infection. The results were confirmed by electron microscopic examination. In group 3 negative biopsy specimens were confirmed by negative stool samples in all cases. Treatment with albendazole and paromomycin did not affect the spore shedding in three patients with E bieneusi infection. By contrast, in a patient with Encephalitozoon sp infection albendazole treatment resulted in clinical improvement together with complete cessation of spore excretion in the stool. CONCLUSION--The Uvitex 2B fluorescence method combines speed, sensitivity, and specificity for the diagnosis and treatment evaluation of intestinal and disseminated microsporidiosis.

ADHESION OF COAGULASE-NEGATIVE STAPHYLOCOCCI TO BIOMATERIALS

The adhesion of two Staphylococcus epidermidis strains and one Staphylococcus saprophyticus strain on to poly(tetrafluorethylene-co-hexafluorpropylene) (FEP)-fluorocarbon and cellulose acetate was studied in vitro. Both S. epidermidis strains showed a more hydrophobic character than the encapsulated S. saprophyticus as determined by the bacterial affinity towards xylene. Staphylococcus epidermidis showed a significantly higher adhesion on to the hydrophobic FEP than S. saprophyticus. The adhesion of staphylococci on to the more hydrophilic cellulose acetate was always low. Treatment of S. epidermidis with pepsin or extraction with aqueous phenol yielded cells with a decreased hydrophobicity, which resulted in a decreased adhesion on to FEP. Cells with a decreased hydrophobicity showed a lower rate of reaggregation in suspension. The hydrophobicity and the adhesion on the FEP of S. epidermidis were not affected by exposure to a subminimal inhibitory concentration of penicillin. The strong interaction between S. epidermidis and FEP, which appeared not to be influenced by the age or the metabolic stage of the bacteria, is mainly caused by hydrophobic bonding.

Cognitive Impairment in Adults with Good Recovery after Bacterial Meningitis

Adults without neurologic sequelae after bacterial meningitis are supposed to live without restrictions. Neuropsychological outcome was assessed in 51 adults from a prospective cohort with good recovery, defined as Glasgow Outcome Scale score 5, after pneumococcal or meningococcal meningitis. Patients who recovered well after pneumococcal meningitis showed cognitive slowness (P=.001). A cognitive disorder was found in 27% of these patients. Patients who previously had meningococcal meningitis were not significantly different from control subjects. Scores on general health and quality of life questionnaires revealed lower scores for patients with meningitis, which were related to cognitive slowing (R, -0.46 to -0.38). In conclusion, adults surviving pneumococcal meningitis were at significant risk of neuropsychological abnormalities, even if they were clinically well recovered.

Adhesion of Staphylococcus epidermidis and Staphylococcus saprophyticus to a hydrophobic biomaterial

The relative surface charge and hydrophobicity of 16 strains of Staphylococcus epidermidis showed large variations. For this species no relationship between the two surface parameters was found. A highly negative surface charge was observed in all seven encapsulated strains (one S. epidermidis and six Staphylococcus saprophyticus strains). The adhesion of the staphylococci to fluorinated polyethylene-propylene films was not related to the relative surface charge and the hydrophobicity of the bacteria. On films pre-exposed to human plasma, the bacterial adhesion was substantially reduced. Mechanisms involved in the adhesion of coagulase-negative staphylococci to this biomaterial are discussed.

High Seroprevalence of Encephalitozoon Species in Immunocompetent Subjects

Encephalitozoon species are important pathogens in human immunodeficiency virus-infected patients. However, in immunocompetent persons, little is known about Encephalitozoon infections, mainly because of the lack of reliable diagnostic tests. To improve diagnosis, three serologic techniques that use Encephalitozoon intestinalis as antigen were developed: an ELISA, an immunofluorescence technique (IFAT), and a counterimmunoelectrophoresis (CIE) method. The serologic response against E. intestinalis was studied in sera from 300 Dutch blood donors and 276 pregnant French women. For confirmation of specificity, sera from 150 subjects with various infectious and noninfectious diseases were examined. ELISA, IFAT, and CIE were specific for microsporidia infections, and IFAT and CIE were specific for Encephalitozoon infections. High antibody titers against Encephalitozoon organisms were found in 24 (8%) of 300 Dutch blood donors and in 13 (5%) of 276 pregnant French women. The high seroprevalence against Encephalitozoon species in Dutch blood donors and French women suggests that Encephalitozoon infection is common in immunocompetent subjects.

Association of Human FcγRIIa (CD32) Polymorphism with Susceptibility to and Severity of Meningococcal Disease

Phagocytosis of bacteria constitutes an important defense mechanism against invasive bacterial diseases. Efficacy of phagocytosis by polymorphonuclear neutrophils is known to vary between allotypes of Fc gamma RIIa (a class of Fc receptors for immunoglobulins that is constitutively expressed on neutrophils). We compared the distribution of Fc gamma RIIa-R131 and Fc gamma RIIa-H131 allotypes in 98 Slavic complement-sufficient patients with meningococcal disease with that of the allotypes in 107 healthy controls. A strong association was found between the IIa-R/R131 allotype and the development of meningococcal disease after the age of 5 years, compared with IIa-R/H131 and IIa-H/H131 allotypes (P < .03; odds ratio [OR], 2.9). A severe course of meningococcal disease was observed in 21 (68%) of 31 episodes in patients with IIa-R/R131 genotype and in 22 (54%) of 41 episodes in patients with IIa-R/H131 genotype, in contrast to eight (31%) of 26 episodes in patients with IIa-H/H131 genotype (P < .02; OR, 4.7). Our data show that individuals older than 5 years of age who have the IIa-H/H131 allotype are less susceptible to severe meningococcal disease than are individuals with the IIa-R/R131 or IIa-R/H131 genotype.