Biomedical subjects

Cees M Verduin

Publications and source records attributed to Cees M Verduin.

7 recordsLinked to original sources

PubMed2005

Moraxella catarrhalis is only a weak activator of the mannose-binding lectin (MBL) pathway of complement activation.

A hemolytic bystander assay was used to assess the functional serum mannose-binding lectin (MBL) activating capacity of five isolates of Moraxella catarrhalis obtained from children who suffered recurrent acute otitis media episodes. Results showed that this organism is only a poor activator of the lectin pathway of complement activation, with subsequent consequences for the etiology of otitis media by this organism.

Child↗

PubMed2004

A novel plasmid (pEMCJH03) isolated from moraxella catarrhalis possibly useful as a cloning and expression vector within this species.

A preliminary screening study of six Moraxella catarrhalis isolates from primary school children in the Netherlands identified a small 3.5 kb plasmid (pEMCJH03), containing four open reading frames, which encoded three mobilizing and one replicase protein. Insertion of a kanamycin containing transposon (yielding pEMCJH04) allowed selection and isolation of the plasmid in Escherichia coli. Natural transformation of pEMCJH04 into M. catarrhalis was successful for 25% (3/12) of non-isogenic isolates, with no link between (lack of) transformability and genetic lineage or (lack of) transformability and complement phenotype, though the transformation efficiency was found to be rather low at approximately 615CFU/microg (range=60-1040CFU/microg ). This is only the second publication detailing a plasmid isolated from this important respiratory pathogen, and the ability to clone and express foreign proteins in M. catarrhalis using pEMCJH04 could help in the development of a vaccine expression vector, as well as providing a useful tool for studying promoter activity and in complementation studies of gene knockout mutants.

Bacterial Proteins↗

PubMed2003

A case of Mycoplasma hominis meningo-encephalitis in a full-term infant: rapid recovery after start of treatment with ciprofloxacin.

UNLABELLED: The role of Mycoplasma hominisas a causative agent for neonatal sepsis and meningitis is still unclear. Meningitis secondary to M. hominisis well-described in the literature; however, M. hominiscan also be isolated from cerebrospinal fluid (CSF) obtained from infants without signs of meningitis. We present a case of a full-term infant with meningo-encephalitis with seizures, epileptic activity on the EEG, inflammation of brain tissue on a CT scan, and cloudy CSF containing elevated cell counts, decreased glucose levels and elevated protein levels. M. hominiswas identified from the CSF by culture and by polymerase chain reaction (PCR) as the only possible causative agent. Furthermore, while empiric antibiotic and antiviral treatment for neonatal sepsis had failed, the meningo-encephalitis promptly responded upon antibiotic treatment with ciprofloxacin (20 mg/kg per day i.v.), to which M. hominisis susceptible. CONCLUSION: A meningo-encephalitis developed due to infection with M. hominisin a full-term infant, from which he recovered rapidly after start of treatment with ciprofloxacin.

Anti-Infective Agents↗

PubMed2002

Fusidic acid cream in the treatment of impetigo in general practice: double blind randomised placebo controlled trial.

OBJECTIVE: To test the hypothesis that fusidic acid would not increase the treatment effect of disinfecting with povidone-iodine alone in children with impetigo. DESIGN: Randomised placebo controlled trial. SETTING: General practices in Greater Rotterdam. PARTICIPANTS: 184 children aged 0-12 years with impetigo. MAIN OUTCOME MEASURES: Clinical cure and bacterial cure after one week. RESULTS: After one week of treatment 55% of the patients in the fusidic acid group were clinically cured compared with 13% in the placebo group (odds ratio 12.6, 95% confidence interval 5.0 to 31.5, number needed to treat 2.3). After two weeks and four weeks the differences in cure rates between the two groups had become smaller. More children in the placebo group were non-compliant (12 v 5) and received extra antibiotic treatment (11 v 3), and more children in the placebo group reported adverse effects (19 v 7). Staphylococcus aureus was found in 96% of the positive cultures; no strains were resistant to fusidic acid. CONCLUSIONS: Fusidic acid is much more effective than placebo (when both are given in combination with povidone-iodine shampoo) in the treatment of impetigo. Because of the low rate of cure and high rate of adverse events in the placebo group, the value of povidone-iodine in impetigo can be questioned.

Anti-Bacterial Agents↗

PubMed2002

Extended-interval dosing of tobramycin in neonates: implications for therapeutic drug monitoring.

OBJECTIVE: Our objective was to individualize tobramycin dosing regimens in neonates of various gestational ages with use of early therapeutic drug monitoring. METHODS: This study was performed in neonatal patients with suspected septicemia in the first week of life. All patients received tobramycin, 4 mg/kg per dose, as a 30-minute intravenous infusion, with a gestational age-related initial interval of 48 hours (<32 weeks), 36 hours (32-36 weeks), and 24 hours (> or =37 weeks). The target serum peak and trough serum concentrations were 5 to 10 mg/L and 0.5 mg/L, respectively. Serum trough samples and 1- and 6-hour samples were taken after the first dose. Tobramycin concentrations were used to obtain gestational age-dependent population models with nonparametric expectation maximization software. To investigate the effect of timing of sampling in a second group of patients, serum trough samples and 3- and 8-hour samples were taken after the first dose of tobramycin was administered. Serum trough concentrations were predicted by use of linear pharmacokinetics in both groups and by use of the population models with bayesian feedback of 1 or 2 serum concentrations in the second group. These predicted concentrations were compared with actual serum trough concentrations. The predictive performance of the 1- to 6-hour and 3- to 8-hour models and the population models were compared with a gestational age-related model without therapeutic drug monitoring. RESULTS: A total of 247 patients were analyzed: 206 with 1- to 6-hour serum samples and 41 with 3- to 8-hour serum samples. Peak serum concentrations were above 5 mg/L in 90.8% of cases, and trough serum concentrations were above 1 mg/L in 25.5% of cases. The 3- to 8-hour linear model had a bias of -0.31 mg/L and a precision of 0.48 mg/L, and it performed significantly better than the 1- to 6-hour model. The best nonparametric expectation maximization model had a bias of -0.11 mg/L and a precision of 0.45 mg/L. None of the models yielded a significant improvement of predictive performance over the model without therapeutic drug monitoring. CONCLUSIONS: Routine early therapeutic drug monitoring does not improve the model-based prediction of initial tobramycin dosing intervals in neonates in the first week of life.

Anti-Bacterial Agents↗

PubMed2002

Moraxella catarrhalis: from emerging to established pathogen.

Moraxella catarrhalis (formerly known as Branhamella catarrhalis) has emerged as a significant bacterial pathogen of humans over the past two decades. During this period, microbiological and molecular diagnostic techniques have been developed and improved for M. catarrhalis, allowing the adequate determination and taxonomic positioning of this pathogen. Over the same period, studies have revealed its involvement in respiratory (e.g., sinusitis, otitis media, bronchitis, and pneumonia) and ocular infections in children and in laryngitis, bronchitis, and pneumonia in adults. The development of (molecular) epidemiological tools has enabled the national and international distribution of M. catarrhalis strains to be established, and has allowed the monitoring of nosocomial infections and the dynamics of carriage. Indeed, such monitoring has revealed an increasing number of B-lactamase-positive M. catarrhalis isolates (now well above 90%), underscoring the pathogenic potential of this organism. Although a number of putative M. catarrhalis virulence factors have been identified and described in detail, their relationship to actual bacterial adhesion, invasion, complement resistance, etc. (and ultimately their role in infection and immunity), has been established in a only few cases. In the past 10 years, various animal models for the study of M. catarrhalis pathogenicity have been described, although not all of these models are equally suitable for the study of human infection. Techniques involving the molecular manipulation of M. catarrhalis genes and antigens are also advancing our knowledge of the host response to and pathogenesis of this bacterial species in humans, as well as providing insights into possible vaccine candidates. This review aims to outline our current knowledge of M. catarrhalis, an organism that has evolved from an emerging to a well-established human pathogen.

Adult↗

PubMed2002

Pathological and therapeutic significance of cellular invasion by Proteus mirabilis in an enterocystoplasty infection stone model.

Proteus mirabilis infection often leads to stone formation. We evaluated how bacterium-mucin adhesion, invasion, and intracellular crystal formation are related to antibiotic sensitivity and may cause frequent stone formation in enterocystoplasties. Five intestinal (Caco-2, HT29, HT29-18N2, HT29-FU, and HT29-MTX) and one ureter cell line (SV-HUC-1) were incubated in artificial urine with five Proteus mirabilis strains. Fluorescence-activated cell sorting (FACS), laser scanning microscopy, and electron microscopy evaluated cellular adhesion and/or invasion, pathologic changes to mitochondria, and P. mirabilis-mucin colocalization (MUC2 and MUC5AC). An MTT (thiazolyl blue tetrazolium bromide) assay and FACS analysis of caspase-3 evaluated the cellular response. Infected cells were incubated with antibiotics at dosages representing the expected urinary concentrations in a 10-year-old, 30-kg child to evaluate bacterial invasion and survival. All cell lines showed colocalization of P. mirabilis with human colonic mucin (i.e., MUC2) and human gastric mucin (i.e., MUC5AC). The correlation between membrane mucin expression and invasion was significant and opposite for SV-HUC-1 and HT29-MTX. Microscopically, invasion by P. mirabilis with intracellular crystal formation and mitochondrial damage was found. Double membranes surrounded bacteria in intestinal cells. Relative resistance to cotrimoxazole and augmentin was found in the presence of epithelial cells. Ciprofloxacin and gentamicin remained effective. Membrane mucin expression was correlated with relative antibiotic resistance. Cell invasion by P. mirabilis and mucin- and cell type-related distribution and response differences indicate bacterial tropism that affects crystal formation and mucosal presence. Bacterial invasion seems to have cell type-dependent mechanisms and prolong bacterial survival in antibiotic therapy, giving a new target for therapeutic optimalization of antibiotic treatment.

Anti-Bacterial Agents↗