Biomedical subjects
Publications and source records attributed to J Verhoef.
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Nucleic Acid Sequence Based Amplification (iNASBA), an isothermal amplification technique for nucleic acids, was evaluated for the identification of medically important Candida species using primers selected from 18S rRNA sequences conserved in fungi. An RNA fragment of 257 nucleotides was amplified for Candida albicans. Nineteen different fungi were tested for rRNA amplification with the NASBA. All were positive when analyzed on agarose gel, whereas human RNA was negative. For the identification of Candida species, NASBA amplification products were analyzed in an enzyme bead-based detection format, using species-specific biotinylated probes and a generic Candida HRPO probe or a membrane-based system using biotinylated probes and avidin-HPRO. Discrimination of the major human pathogenic Candida spp. was based on a panel of biotinylated probes for C. krusei, C. tropicalis, C. albicans, C. glabrata, and C. lusitaniae. Using rRNA dilutions obtained from pure cultures of C. albicans, the combination of NASBA and the enzymatic bead-based detection yielded a sensitivity equivalent to 0.01 CFU. In a model system using 1 ml of artificially contaminated blood as few as 1-10 CFU of C. albicans could be detected. Testing of 68 clinical blood samples from patients suspected of candidemia showed that eight samples were positive for C. albicans and one for C. glabrata. Testing of 13 clinical plasma samples from patients suspected of fungemia identified the presence of C. albicans in two specimens. The whole procedure of sample preparation, amplification and identification by hybridization can be performed in 1 day. This speed and the observed sensitivity of the assay make the NASBA a good alternative to PCR for the detection of candidemia.
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The newer fluoroquinolones generally have greater potency against Gram-positive cocci including Streptococcus pneumoniae. In this study, we report the activity of gatifloxacin (formerly AM-1155 or CG5501) compared with penicillin, erythromycin, and four other peer drugs, tested against 2284 strains isolated in North America (Canada and United States), Latin America (six nations), and Europe in 1997. Reference broth microdilution methods were used and results were interpreted by consensus standards. Gatifloxacin demonstrated uniform potency against pneumococci across all monitored geographic areas (MIC90, 0.5 microgram/mL; > or = 99.6% of strains inhibited at < or = 1 microgram/mL). This activity was comparable to trovafloxacin (MIC90, 0.5 microgram/mL) and sparfloxacin (MIC90, 0.5 microgram/mL) and two- to four-fold greater than that of ciprofloxacin or levofloxacin. The most resistant strains to the fluoroquinolones had mutations in both par C (Ser 79-->Phe) and gyr A (Ser83-->Lys or Phe). Penicillin resistance (MIC, > or = 0.12 microgram/mL) rates varied from 27.6% in Europe to 55.7% in Latin America. Macrolide resistance was greatest in Europe and the United States. Gatifloxacin appears to be a promising new fluoroquinolone for clinical use in respiratory tract infections commonly caused by S. pneumoniae.
The SENTRY Antimicrobial Surveillance Program, an international study of blood stream infections (BSIs), detected 170 episodes of candidemia in 20 European medical centers (13 nations) between January and December, 1997. Twenty-three percent of the candidal BSI occurred in patients hospitalized in an intensive care unit, 21% in patients in an internal medicine service, 13% in patients in a surgical service, and 9% in patients in an oncology service. Overall, 53% of the BSI were attributable to Candida albicans followed in prevalence by C. parapsilosis (21%), C. glabrata (12%), C. tropicalis (6%), C. famata (2%), C. krusei (1%), and C. inconspicua (1%). As observed previously in Canada and Latin America, C. parapsilosis and not C. glabrata, was the most common non-albicans species causing yeast BSI in Europe. The proportion of these candidemias attributable to C. albicans varied widely from 0-100% among the 20 European centers. Among the different species of Candida, resistance to fluconazole (MIC, > or = 64 micrograms/mL) and itraconazole (MIC, > or = 1.0 microgram/mL) was observed with C. glabrata and C. krusei and was observed more rarely among other species (e.g., C. inconspicua). Isolates of C. albicans, C. parapsilosis, C. tropicalis, and C. guilliermondii were all highly susceptible to both fluconazole and itraconazole. Furthermore, the investigational triazoles (BMS-207147, Sch 56592, and voriconazole) and an echinocandin (MK-0991) all demonstrated potent in vitro activity (MIC90s, 0.5, 0.5, 1.0, and 2.0 micrograms/mL, respectively) against these isolates. Continued surveillance at an international level will be important to monitor trends in species distribution and antifungal susceptibility among invasive strains of Candida.
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The in-vitro activities of gatifloxacin, trovafloxacin, levofloxacin, sparfloxacin, ofloxacin, and ciprofloxacin were tested against 9,682 clinical bacterial isolates from 20 European university hospitals participating in the European SENTRY surveillance programme. Gatifloxacin and trovafloxacin exhibited the highest activities against gram-positive cocci, while levofloxacin, ofloxacin, ciprofloxacin, and gatifloxacin were the most active against Enterobacteriaceae. Ciprofloxacin and levofloxacin showed the highest antimicrobial activities against Pseudomonas spp., while gatifloxacin and trovafloxacin were the most active against Acinetobacter spp. and Stenotrophomonas maltophilia. All Haemophilus spp. and Moraxella catarrhalis isolates were fully susceptible to all quinolones tested. Overall, the new quinolones, showed improved activity against gram-positive cocci and gram-negative non-fermenters while retaining their broad-spectrum activity against gram-negative bacilli.
OBJECTIVE: The SENTRY antimicrobial surveillance program was established to monitor the occurrence and antimicrobial susceptibility of bacterial pathogens via an international network of sentinel hospitals. MATERIAL AND METHODS: Microorganisms were forwarded to the reference laboratory for testing against various antimicrobial agents using broth microdilution. Twenty European hospitals referred 286 Streptococcus pneumoniae, 309 Haemophilus influenzae, and 167 Moraxella catarrhalis isolates during the first 10 months of the study, starting in April 1997. RESULTS: Seven percent of the S. pneumoniae isolates were highly resistant to penicillin, and 21% showed intermediate resistance. The highly resistant pneumococcal isolates came from Coimbra, Barcelona, Athens, and London, whereas the intermediate penicillin-resistant isolates were received from all participating countries. The incidence of intermediate penicillin-resistant pneumococci was lowest in Lausanne, Freiburg and Duesseldorf, London, and Utrecht and highest in southern European countries. Fifty-five percent of the penicillin-resistant S. pneumoniae were also resistant to erythromycin, and 35% to clindamycin. Sparfloxacin, trovafloxacin, levofloxacin, and vancomycin were fully active against pneumococcal isolates. Haemophilus influenzae isolates were generally highly susceptible to most of the antibiotics tested, and 92% of the M. catarrhalis isolates were resistant to penicillin. Susceptibility to cephalosporins, ciprofloxacin, levofloxacin, and rifampicin was 100%. CONCLUSION: Penicillin may no longer be the first-choice drug for empirical treatment of pneumococcal infections. The newer fluoroquinolones may play a role in the empirical treatment of community-acquired pneumonia.
One century ago, Christiaan Eijkman was appointed Professor of Bacteriology at the Utrecht University, The Netherlands. Despite his appointment to teach bacteriology, Christiaan Eijkman made his main contribution to medical science not in bacteriology but in nutrition. He discovered that Beri-Beri was not an infection but a nutritient deficiency (later called vitamin-deficiency) and was awarded the Nobel Prize for Medicine in 1929 for these observations. These landmark studies were made in the former Dutch East Indies. Interestingly, the results of his studies were presented in the Dutch language, in the medical journal of the Dutch East Indies. As a professor of Bacteriology, his work was the beginning of an important school in biochemistry in The Netherlands.
BACKGROUND: Interdigestive small bowel motility has a regulatory function on the microflora of the upper small bowel. Here we investigate the effects of ABT-229 and octreotide on morphine-induced dysmotility, the accompanying bacterial overgrowth and bacterial translocation. METHODS: Rats were fitted with jejunal myoelectrodes and a subcutaneous cannula for continuous infusion of saline or morphine. Fasting motility was measured for 6 h on four occasions: one control measurement (day 0) and three measurements on consecutive days (days 1-3) while receiving saline alone (group A), morphine alone (group B), saline + ABT-229 (group C), morphine + ABT-229 (group D), saline + octreotide (group E) or morphine + octreotide (group F). Samples from the mesenteric lymph node complex (MLN), liver, spleen, duodenum and ileum were taken for quantitative microbial culturing on day 4. RESULTS: Neither ABT-229 nor octreotide increased the number of propagated activity fronts during saline infusion. During morphine-induced dysmotility, ABT-229 induced more propagated activity fronts in group D (13.4, 9.8 and 8.8 per 6 h) than in group B (7.0, 4.5, 3.8 per 6 h) on days 1, 2 and 3 (P < 0.05 for all days) Octreotide did not induce more propagated activity fronts. Disruption of small bowel motility by morphine led to bacterial overgrowth in the duodenum. ABT-229 and octreotide did not reduce the bacterial growth levels. The total incidence of bacterial translocation was significantly higher in the morphine-treated animals than in the saline-treated animals. Neither ABT-229 nor octreotide reduced the bacterial translocation incidence. The number of propagated activity fronts on day 3 and duodenal bacterial growth correlated significantly in groups A, E and F. CONCLUSIONS: ABT-229, but not octreotide, reduced morphine induced dysmotility. Small bowel bacterial overgrowth and bacterial translocation were not prevented. Fasting small bowel motility has a regulatory function on the intestinal microflora of the upper small bowel.
At the University Medical Center, Utrecht, methicillin-resistant Staphylococcus aureus (MRSA) patients are considered lifelong MRSA carriers and potentially contagious when readmitted. The purpose of this study was to determine whether patients who become MRSA carriers while in hospital remain colonized after discharge, and whether risk factors for prolonged carriage exist. Thirty-six patients colonized with MRSA during three outbreaks at University Medical Center, Utrecht (group I: 1986-1989), and twenty patients already colonized with MRSA on, or during, admission to the hospital (group II: 1990-1995) were screened for MRSA in two studies. The patients had been discharged from the hospital for periods varying from 15 days to 4.6 years. MRSA was found in five (9%). Four of these patients had skin lesions (wounds), one with an external fixture. The presence of skin- and underlying diseases differed significantly between carriers and non-carriers, supporting the hypothesis that wounds are a major risk factor for long-term MRSA carriage. This study led us to revise our policy concerning readmission of former MRSA patients. We now consider that patients who contracted MRSA in the past no longer need isolation if the following two criteria are met. Absence for at least six months of open wounds, skin lesions, tracheostomy, infections and sources of infection such as abscesses and furuncles, orthopaedic implants, drains, catheters, or tubes. Three MRSA-negative sets of swabs from nose, throat, perineum, urine, and sputum taken at least one hour apart after this six-month period.
Community-acquired pneumonia from enteric gram-negative bacilli is more common in developing than in industrialized countries. We investigated the nasopharyngeal flora in healthy children from Angola, Brazil and The Netherlands to see whether enteric gram-negative bacilli are more often part of the commensal flora in developing countries. Nasopharyngeal specimens were collected from children aged between 4 months and 5 years in day-care centres and immunization clinics. Children who had received antibiotics or were malnourished were excluded. Brazilian and Angolan children had a higher number of household members than Dutch children (5.5 and 7 vs 3.9 mean number of household members, respectively) (p < 0.0001). Enteric and non-fermentative gram-negative bacilli were much more prevalent in Brazilian (50%) and Angolan (57%) children than in Dutch (4%) children (p < 0.0001). By univariate analysis, carriage of enteric gram-negative bacilli was associated with the number of household members (r = 0.26; p < 0.001). The high carriage rate of enteric gram-negative bacilli in children from Angola and Brazil may explain why enteric gram-negative bacilli are a common cause of pneumonia in developing countries.
The population structure of Bordetella pertussis in The Netherlands in 5 successive periods, encompassing 1949-1996, was analyzed by DNA typing ("fingerprinting"). In 10 years following the introduction of wide-scale vaccination in 1953, a decrease in genotypic diversity (GD) was observed, suggesting clonal expansion of strains that were adapted to vaccine-induced immunity. In subsequent periods, GD increased to prevaccination levels, probably reflecting a gradual adaptation of the B. pertussis population involving many lineages. In the 1990s, GD decreased again. This decrease coincided with an antigenic shift in the surface protein pertactin. No evidence was found for changes in DNA types or GD in 1996, when a large pertussis epidemic occurred. Thus, gradual changes in the bacterial population previous to 1996 were probably the cause of the 1996 epidemic. The results herein suggest that vaccination has selected for strains that are adapted to a highly vaccinated population. Similar changes may have occurred in other countries, explaining the reemergence of pertussis in vaccinated populations.
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Macrolide, lincosamide and streptogramin (MLS) antibiotics are chemically distinct inhibitors of bacterial protein synthesis. Resistance to MLS antibiotics may be constitutive or inducible. The purpose of this study is to update our understanding of the prevalence of different forms of MLS resistance in Europe. The analysis of 3653 clinical pneumococcal, staphylococcal and enterococcal isolates exhibited an average percentage of 21.3% and 6.2% intermediate and high-level penicillin-resistant Streptococcus pneumoniae, 21.8% methicillin-resistant Staphylococcus aureus and 11% vancomycin-resistant Enterococcus faecium. Geographical differences in erythromycin and clindamycin resistance in isolates of S. pneumoniae and S. aureus strongly reflect geographical variations in susceptibility to penicillin and methicillin, respectively. A very narrow range of MICs was obtained with quinupristin/dalfopristin, with no S. pneumoniae, S. aureus and E. faecium isolate having an MIC of > 4 mg/L, indicating a possible role of quinupristin/dalfopristin in the treatment of infections by multi-resistant Gram-positive bacteria.
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Resistance among bacteria is on the rise, both in the hospital and in the community. Surveillance is needed for guided empiric treatment and to detect new resistance mechanisms at an early stage. Surveillance shows a wide variation in resistance among hospitals and countries. Especially methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci are uncommon in north western European countries but frequently observed otherwise elsewhere. Among Gram-negative bacteria regional differences are less obvious. Many hospitals all over the world suffer from recurrent outbreaks by Enterobacteriaceae that produce extended spectrum beta-lactamases, Acinetobacter, etc. Because of the evolving pattern of resistance, surveillance should be done at regular intervals in all hospitals and in the community.