Biomedical subjects
Publications and source records attributed to A T Bernards.
The ancient method of larval therapy for treatment of acute and chronic infections has become a revival and a new dimension with introduction of the Biobag (Vitapad). With use of this therapy trauma patients suffering infectious complications can be treated very effective, which can reduce the overall time needed for treatment and can result in diminished invalidity.
An increase in the number of outbreaks of Acinetobacter infection was notified in The Netherlands during 1999-2001. The present study compared the outbreaks at the species and strain levels, and analysed the epidemiology and control measures at the different locations. For each institute, three representative isolates from three patients were identified to the species and strain levels by genotyping methods. A questionnaire investigated the impact of the outbreak, the control measures that were taken, and the possible effects of the measures. Seven outbreaks were associated with Acinetobacter baumannii (three outbreaks with a strain designated strain A, two outbreaks with a strain designated strain B, and one outbreak each with strains designated C and D). An additional outbreak was caused by genomic species 13TU, which is related closely to A. baumannii. Strains B and D were identified as European clones III and II, respectively. Except for two hospitals with outbreaks caused by strain A, there was no known epidemiological link between the participating hospitals. In all hospitals the outbreak occurred on one or several intensive care units, and spread to other departments was noted in two hospitals. The number of patients affected ranged from six to 66 over a period of 2-22 months. In most outbreaks, patients were the likely reservoir from which spread occurred. In all hospitals, a large panel of measures was required to bring the outbreak to an end. Extensive environmental sampling yielded numerous positive samples in most but not all hospitals.
A set of 18 Acinetobacter baumannii isolates, collected prospectively in a Bulgarian hospital during episodes of increased A. baumannii occurrence during 2000-2002, was investigated for genotypic diversity and antibiotic susceptibility. Four genotypes were identified by amplified fragment length polymorphism genomic fingerprinting, one of which (type 1) accounted for 13 isolates, indicating that a specific strain was predominant. The single isolate allocated to type 2 was identified to European clone I. All isolates were resistant to multiple antibiotics, but most retained susceptibility to tobramycin and colistin, and all except one were susceptible to imipenem.
In total, 226 individuals from the community were investigated for faecal carriage of Acinetobacter spp. by broth enrichment culture, followed by growth on blood agar and/or Leeds Acinetobacter Medium (LAM). Acinetobacter baumannii was isolated on both LAM and blood agar from one of 100 specimens in the UK and one of 126 specimens in The Netherlands. The predominant species were Acinetobactor johnsonii and genomic sp. 11, which were cultured from 22 and five specimens, respectively. A. baumannii did not seem to be widespread in the faecal flora of individuals in the community.
Linezolid is the first of a new class of antibacterial agents, the oxazolidinones, to become available. Linezolid has a unique mechanism of action in its inhibition of bacterial protein synthesis in Gram-positive and a number of anaerobic bacteria. Because of this unique mechanism of action, linezolid exhibits no cross-resistance with other antibiotics and is effective against methicillin-resistant staphylococci, penicillin-resistant pneumococci and vancomycin-resistant enterococci. The excellent bioavailability after oral administration (almost 100%) makes it suitable for outpatient treatment and treatment by general practitioners. In the Netherlands, however, the indications for linezolid are limited by its high cost, the availability of other effective antibiotics for the treatment of sensitive micro-organisms, and the toxicity associated with a prolonged treatment period. Resistance to the new agent was reported rather quickly after the introduction of linezolid.
Two outbreaks of multidrug-resistant Acinetobacter baumannii occurred in our hospital. The outbreak strains were eventually isolated from respiratory ventilators, an apparatus used to cool or warm patients, and four continuous veno-venous hemofiltration machines. Removing dust from the machines and replacing all dust filters brought the outbreaks to an end.
Maggots were used as adjunct treatment for infected wounds that showed no response to the classical approach of wound debridement and antibiotic therapy. We summarize findings for 11 patients with necrotic wounds who received treatment with "surgical" maggots (100-2900 applied in 3-10 changes of dressing) for 11-34 days, which apparently aided in tissue remodeling and cure, and describe 2 typical patients in detail.
BACKGROUND AND OBJECTIVES: After storage, low levels of contaminating bacteria in standard blood components can reach bacteraemic levels, causing severe transfusion-associated sepsis. For cord blood (CB), the significance of low levels of contaminating bacteria and the optimal detection method is unknown and not supported by available guidelines. MATERIALS AND METHODS: Spiking experiments and testing of various subfractions of CB units were used to determine the behaviour of bacteria during centrifugation, freezing and thawing. For routine testing of CB, different volumes were compared for the detection of potential pathogens and micro-organisms of low pathogenicity. RESULTS: Centrifugation, as applied to CB fractionation, does not show concentration of bacteria in any particular fraction and supports the possibility of culture of waste fractions. Dimethylsulphoxide (DMSO) and freezing does not affect the viability of bacteria under the conditions used in this study. Owing to the low contamination level, a large sample volume of 20 ml was more sensitive than a 10-ml sample volume. Eighty five per cent of the isolated strains can be considered to be of low pathogenicity. CONCLUSION: When an optimal waste fraction sample volume of 20 ml was cultured, the contamination rate of CB was found to be approximately 13%, with low levels of < 1 colony-forming unit (CFU)/ml. Such levels of bacteria of low pathogenicity are expected to be of clinical importance only when CB is expanded in vitro for a prolonged period of time.
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Between January 1996 and May 1997, a four-fold increased rate of isolation of Serratia marcescens was observed amongst patients admitted to the surgical Intensive Care Unit (SICU) of the Leiden University Medical Center compared to the preceding years. Random amplification of polymorphic DNA showed the involvement of genotypically distinct strains, implicating multiple different sources. After improvement of hygienic measures the frequency of isolation of S. marcescens returned to baseline. A case-control study was performed to assess patient-related risk factors for acquisition of S. marcescens. Nineteen cases and 38 controls were included. Hospital- and SICU-stay were significantly longer in case patients than in controls. By univariate analysis, statistically significant differences were found in body weight, the duration of mechanical ventilatory support, the cumulative use of antimicrobial agents, the use of aminoglycosides, parenteral nutrition and tube feeding. The sum of the number of days per invasive device (deep intravenous lines, arterial lines, wound drains and urinary catheters) was higher in cases than in controls (P = 0.08). Categorically, a cumulative number of device-days > 25 was a statistically significant risk factor for acquisition of S. marcescens. Multivariable logistic regression analysis showed that body weight, parenteral feeding and mechanical ventilation were independent predictors of acquisition of S. marcescens. As transmission of S. marcescens appears to be by the hands of personnel, the identified risk factors may act by necessitating an increased frequency and intensity of direct contacts.
Acinetobacter junii caused sepsis in six preterm infants in our neonatal unit within 48 h. Each infant with clinical signs of systemic infection and activation of the acute phase response had two positive blood cultures with Acinetobacter junii. The sudden onset, the short duration of the outbreak and the fact that none of the infants were colonized by A. junii suggested a common source of A. junii administered directly into the blood. The only feature shared by all six affected newborns was an intravenous fat emulsion (Intralipid 10%), which was shown to be an excellent growth medium for A. junii. Sepsis did not occur in four infants with 20% fat emulsion or amino acids only. Vaminolact did not support growth of the outbreak strain. The immediate source of the outbreak could not be identified: samples of the actual feeds given were not available for investigation, but A. junii was not isolated from parenteral solutions with identical batch numbers used in the septic infants. We conclude that Acinetobacter junii can cause a life-threatening infection in preterm neonates. Contaminated intravenous fat emulsion is implicated as a possible source of the infection. As a part of rigid infection control, intravenous feedings should be prepared under aseptic conditions.
BACKGROUND: The Dutch guideline on hospital policy for the prevention of nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA) states that patients transferred from hospitals abroad must be placed in strict isolation immediately on admission to a hospital in the Netherlands. Three patients colonized with both MRSA and a multiresistant Acinetobacter were transferred from hospitals in Mediterranean countries to 3 different hospitals in the Netherlands. Despite isolation precautions, Acinetobacter spread in 2 of the 3 hospitals, whereas nosocomial spread of MRSA did not occur. METHODS: For outbreak analysis, the Acinetobacter isolates, identified as Acinetobacter baumannii by the use of amplified ribosomal DNA restriction analysis, were comparatively typed by 4 methods. Comparison of isolation measures in the hospitals was performed retrospectively. RESULTS: In the 2 hospitals in which nosocomial spread of Acinetobacter occurred, most of the epidemiologically related isolates were indistinguishable from the index strains. In these 2 hospitals, isolation measures were in concordance with those recommended for the prevention of contact transmission. The precautions of the hospital in which no outbreak occurred included the prevention of airborne transmission. CONCLUSIONS: Precautions recommended for multiresistant gram-negative organisms are insufficient for the prevention of nosocomial spread of multiresistant Acinetobacter. The airborne mode of spread of acinetobacters should be taken into account, and guidelines should be revised accordingly.
Septicaemia caused by Acinetobacter occurred in six infants in the neonatal unit. A total of 18 acinetobacters were isolated from blood cultures, cultures of intravascular catheters, and surveillance cultures. Twelve isolates from the six affected infants were identified as Acinetobacter junii by the use of a novel method, amplified ribosomal DNA restriction analysis (ARDRA). Typing of the organisms using the biochemical profiles of the API 20NE system, antibiogram typing, cell envelope protein electrophoresis, and PCR fingerprinting with two primer sets, ERIC1/ERIC2 and ERIC2/ 1026, showed that these 12 isolates were indistinguishable, whereas the remaining six isolates were different. The six infants recovered after therapy with ciprofloxacin alone in five cases and with a combination of ciprofloxacin and gentamicin in one case. This study showed that A. junii is capable of causing a serious, though non-fatal infection in neonates. The combined use of genotypic and phenotypic methods allowed the rapid separation of epidemic from non-epidemic isolates. It is concluded that for a better understanding of the role of the various Acinetobacter genomic species in human pathology, identification of acinetobacters according to the recent taxonomy is imperative.
A collection of 130 Acinetobacter strains identified by DNA hybridization to 18 different genomic species was used to assess the ability of the API 20NE system (bioMérieux, France) to identify Acinetobacter genomic species and to determine its accuracy. Fifty-eight (87%) of the 67 strains of genomic species defined in the database (version 5.1) were identified to the appropriate genomic species. The Acinetobacter baumannii strains and the Acinetobacter haemolyticus strains were all identified correctly. Three of five Acinetobacter junii strains, three of eight Acinetobacter johnsonii strains, and 11 of 13 Acinetobacter lwoffii strains were also identified correctly. The 58 correctly identified strains represented 45% of the total 130 strains. Thirty-six of the 72 inappropriately identified strains were designated Acinetobacter baumannii. Thirty-one of these 36 strains belonged to genomic species 1 (Acinetobacter calcoaceticus), 3, or 13TU. Analysis of the profiles showed that the API system does not discriminate between genomic species 1, 2, 3, and 13TU. Lumping of these groups into the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in the API 20NE database would make the system considerably more accurate. Incorporation of these data into the database may improve identification of the remaining genomic species, including some that are not defined. However, the discriminative power of the tests in the API galleries is insufficient for correct identification of all Acinetobacter genomic species.
Identification of Acinetobacter spp. to the DNA group level by phenotypic techniques is problematic, and there is a need for an alternative identification method for routine use. The present study validated the suitability of a rapid identification technique based on tRNA spacer (tDNA) fingerprinting in comparison with that of a commercially available assay involving carbon source utilization tests (Biolog MicroStation System) for identifying the 21 DNA-DNA hybridization groups belonging to the genus. For this purpose, 128 strains identified previously by DNA-DNA hybridization were analyzed by both techniques. tDNA fingerprinting was highly reproducible and classified all strains into 17 groups. Six DNA groups belonging to the A. calcoaceticus-A. baumannii complex were grouped into two distinct clusters, indicating the high degree of genetic similarity within this complex. Strains of the more recently described DNA groups BJ13 to BJ16 were ambiguously grouped and displayed three pattern types. The software used with the commercial carbon source utilization method grouped the 128 strains into 12 clusters, explaining the less discriminatory power of this system. We conclude that tDNA fingerprinting offers a quick and reliable method for the routine differentiation of most Acinetobacter spp. at the subgenus level.
An algometer was used to study the pain threshold (PT) on pressure at the joint capsules of the wrists, elbows, knees, ankles and at paravertebral soft tissues in 57 patients with juvenile chronic arthritis (JCA) and 69 healthy controls, aged 6-17 yr. The PTs were correlated to visual analogue scales (VAS) and values of articular disease activity, to define their relation with pain perception and joint inflammation. The PTs in JCA patients were significantly lower than in their healthy peers, both in children with active inflammation as well as in children without detectable inflammation. The JCA group with active inflammation showed significant lower PTs than without detectable inflammation. Disease activity and VAS correlated significantly with PT (r = -0.5). There is an enhanced sensitivity to noxious stimuli in all measured body areas, suggesting a change in the pain processing system in JCA. The sensitivity endures in JCA patients without clinically active disease, probably due to prolonged central sensitization after periods of active disease.
A collection of 129 Acinetobacter strains belonging to DNA groups (genomic species) 1-14 (1-7 and 10-12 sensu Bouvet and Grimont; 8 and 13-14 sensu Tjernberg and Ursing) were investigated for their ability to oxidise 95 carbon sources in the Biolog system. The strain groupings obtained by cluster analysis with the Biolog software were compared with the results of DNA-DNA hybridisation studies. Strains of DNA groups 1 (A. calcoaceticus), 2 (A. baumannii), 3 and 13 were linked in one cluster, as were DNA groups 4 (A. haemolyticus) and 6, DNA groups 10 and 11, and DNA groups 8 (A. lwoffii) and 12 (A. radioresistens). Strains of DNA group 5 (A. junii) were grouped in a single cluster with one strain of DNA group 4. Strains of DNA groups 7 (A. johnsonii) and 14 formed separate clusters. With the exception of the linkage of DNA groups 8 and 12, these results correlated with classification of reference strains of the DNA groups by DNA-DNA hybridisation, but six strains of four different DNA groups were not allocated to the clusters of their respective DNA groups. In the case of DNA groups 4, 5, 6, 7, 10, 11 and 14, at least one carbon source oxidation test could be used to differentiate them from the other DNA groups.
AIMS: To investigate the diagnostic value of mucosal IgA and IgG Helicobacter pylori antibodies. METHODS: The study population comprised 209 consecutive patients with severe dyspeptic complaints referred for upper gastrointestinal endoscopy. A positive culture or histological identification of H pylori in gastric biopsy specimens, or both, were used to confirm infection. Specific IgA and IgG H pylori antibodies were determined using a modified ELISA technique. RESULTS: Of the 209 patients, 137 were infected with H pylori. The diagnostic value of systemic IgA and IgG H pylori antibodies was confirmed. Systemic IgA antibodies had a sensitivity of 76.6% (95% confidence interval 69.5-83.7) and a specificity of 94.4% (89.1-99.7). The sensitivity and specificity for systemic IgG antibodies were, respectively, 97.1% (94.3-99.9) and 98.6% (95.9-100). A moderate but clinically important correlation was found between local and systemic IgA and IgG. Mucosal IgA H pylori antibodies had a sensitivity of 98.5% (96.5-100) and a specificity of 91.7% (85.3-98.1), while for IgG these figures were, respectively, 88.3% (82.9-93.7) and 98.6% (95.9-100). As a diagnostic test mucosal IgA H pylori antibodies were comparable with culture and histology. CONCLUSION: Determination of local IgA and IgG H pylori antibody levels is a highly sensitive and specific test for the diagnosis of H pylori infection.