22 research outputs found
Density and molecular epidemiology of Aspergillus in air and relationship to outbreaks of Aspergillus infection
After five patients were diagnosed with nosocomial invasive aspergillosis
caused by Aspergillus fumigatus and A. flavus, a 14-month surveillance
program for pathogenic and nonpathogenic fungal conidia in the air within
and outside the University Hospital in Rotterdam (The Netherlands) was
begun. A. fumigatus isolates obtained from the Department of Hematology
were studied for genetic relatedness by randomly amplified polymorphic DNA
(RAPD) analysis. This was repeated with A. fumigatus isolates
contaminating culture media in the microbiology laboratory. The density of
the conidia of nonpathogenic fungi in the outside air showed a seasonal
variation: higher densities were measured during the summer, while lower
densities were determined during the fall and winter. Hardly any variation
was found in the numbers of Aspergillus conidia. We found decreasing
numbers of conidia when comparing air from outside the hospital to that
inside the hospital and when comparing open areas within the hospital to
the closed department of hematology. The increase in the number of
patients with invasive aspergillosis could not be explained by an increase
in the number of Aspergillus conidia in the outside air. The short-term
presence of A. flavus can only be explained by the presence of a point
source, which was probably patient related. Genotyping A. fumigatus
isolates from the department of hematology showed that clonally related
isolates were persistently present for more than 1 year. Clinical isolates
of A. fumigatus obtained during the outbreak period were different from
these persistent clones. A. fumigatus isolates contaminating culture media
were all genotypically identical, indicating a causative point source.
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Rapid detection of methicillin resistance in Staphylococcus aureus isolates by the MRSA-screen latex agglutination test
The slide agglutination test MRSA-Screen (Denka Seiken Co., Niigata,
Japan) was compared with the mecA PCR ("gold standard") for the detection
of methicillin resistance in Staphylococcus aureus. The MRSA-Screen test
detected the penicillin-binding protein 2a (PBP2a) antigen in 87 of 90
genetically diverse methicillin-resistant S. aureus (MRSA) stock culture
strains, leading to a sensitivity of 97%. The three discrepant MRSA
strains displayed positive results only after induction of the mecA gene
by exposure to methicillin. Both mecA PCR and MRSA-Screen displayed
negative results among the methicillin-susceptible S. aureus strains (n =
106), as well as for Micrococcus spp. (n = 10), members of the family
Enterobacteriaceae (n = 10), Streptococcus pneumoniae (n = 10), and
Enterococcus spp. (n = 10) (specificity = 100%). Producing the same PBP2a
antigen, all 10 methicillin-resistant Staphylococcus epidermidis strains
score positived in both the latex test and the mecA PCR. Consequently, the
MRSA-Screen test should be applied only after identification of the MRSA
strain to the species level to rule out coagulase-negative staphylococci.
In conclusion, due to excellent specificity and sensitivity the
MRSA-Screen latex test has the potential to be successfully used for
routine applications in the microbiology laboratory
Quality of probiotic products for preterm infants: Contamination and missing strains
Probiotics are effective in reducing necrotising enterocolitis in preterm infants, but routine use is not generally adopted. We describe a safety issue concerning contamination by pathogenic bacteria and missing of labelled strains in a probiotic product widely used in neonatal care. We recommend all centres using probiotics in the care of vulnerable patients to consider product safety checks in addition to the quality reports of manufacturers. Meanwhile, clinicians and manufacturers should collaborate to define quality standards for probiotic products in clinical settings as long as specific international regulations are lacking
Streptococcus pneumoniae enhances human respiratory syncytial virus infection in vitro and in vivo
Human respiratory syncytial virus (HRSV) and Streptococcus pneumoniae are important causative agents of respiratory tract infections. Both pathogens are associated with seasonal disease outbreaks in the pediatric population, and can often be detected simultaneously in infants hospitalized with bronchiolitis or pneumonia. It has been described that respiratory virus infections may predispose for bacterial superinfections, resulting in severe disease. However, studies on the influence of bacterial colonization of the upper respiratory tract on the pathogenesis of subsequent respiratory virus infections are scarce. Here, we have investigated whether pneumococcal colonization enhances subsequent HRSV infection. We used a newly generated recombinant subgroup B HRSV strain that expresses enhanced green fluorescent protein and pneumococcal isolates obtained from healthy children in disease-relevant in vitro and in vivo model systems. Three pneumococcal strains specifically enhanced in vitro HRSV infection of primary well-differentiated normal human bronchial epithelial cells grown at air-liquid interface, whereas two other strains did not. Since previous studies reported that bacterial neuraminidase enhanced HRSV infection in vitro, we measured pneumococcal neuraminidase activity in these cultures but found no correlation with the observed infection enhancement in our model. Subsequently, a selection of pneumococcal strains was used to induce nasal colonization of cotton rats, the best available small animal model for HRSV. Intranasal HRSV infection three days later resulted in strain-specific enhancement of HRSV replication in vivo. One S. pneumoniae strain enhanced HRSV both in vitro and in vivo, and was also associated with enhanced syncytium formation in vivo. However, neither pneumococci nor HRSV were found to spread from the upper to the lower respiratory tract, and neither pathogen was transmitted to naive cage mates by direct contact. These results demonstrate that pneumococcal colonization can enhance subsequent HRSV infection, and provide tools for additional mechanistic and intervention studies
Improved diagnosis of Trichomonas vaginalis infection by PCR using vaginal swabs and urine specimens compared to diagnosis by wet mount microscopy, culture, and fluorescent staining
Four vaginal cotton swab specimens were obtained from each of 804 women
visiting the outpatient sexually transmitted disease clinic of the Erasmus
University Medical Center Rotterdam, Rotterdam, The Netherlands, for
validation of various forms of Trichomonas vaginalis diagnostic
procedures. One swab specimen was immediately examined by wet mount
microscopy, a second swab was placed in Kupferberg's Trichosel medium for
cultivation, and two swabs were placed in phosphate-buffered saline (PBS),
pH 7.2. The resulting PBS suspension was used for direct staining with
acridine orange and fluorescence microscopy, inoculation of modified
Diamond's culture medium, and a PCR specific for T. vaginalis. A total of
70 samples positive in one or more of the tests were identified: 31 (3.8%)
infections were detected by wet mount microscopy, and 36 (4.4%) were
The Rotterdam Study: 2012 objectives and design update
The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods
Evaluation of human acellular dermis versus porcine acellular dermis in an in vivo model for incisional hernia repair
The Rotterdam Study: 2010 objectives and design update
The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in close to a 1,000 research articles and reports (see www.epib.nl/rotterdamstudy). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods
Retesting for genital Chlamydia trachomatis among visitors of a sexually transmitted infections clinic: randomized intervention trial of home- versus clinic-based recall
Background: Reinfections of Chlamydia trachomatis (Ct) are common. In a two-armed intervention study at an urban STI clinic in the Netherlands, heterosexual Ct-positive visitors received an invitation for retesting after 4-5 months. Interventions were either home-based sampling by mailed test-kit, or clinic-based testing without appointment. Methods: Data collection included socio-demographic and sexual behavioural variables at first (T0) and repeat test (T1). Participation in retesting, prevalence and determinants of repeat infection among study participants are described and compared with findings from non-participants. Results: Of the 216 visitors enrolled in the study, 75 accepted retesting (35%). The retest participation was 46% (50/109) in the home group versus 23% (25/107) in the clinic group (p = 0.001). Men were less often retested than women (15% versus 43%, p < 0.001). The overall chlamydia positivity rate at retest was 17.3% (13/75) compared to 12.4% seen at all visits at the STI clinic in 2011. Repeated infections were more frequent among non-Dutch than Dutch participants (27.0% versus 7.9%; p = 0.04 Conclusion: The high rate of repeated infections indicates the need for interventions to increase retesting; improvement of partner-management and risk reduction counselling remain necessary. Home-based testing was more effective than clinic-based testing. However other strategies, including self-triage of patients, may also increase repeat testing rates and personal preferences should be taken into account
Density and Molecular Epidemiology of Aspergillus in Air and Relationship to Outbreaks of Aspergillus Infection
After five patients were diagnosed with nosocomial invasive aspergillosis caused by Aspergillus fumigatus and A. flavus, a 14-month surveillance program for pathogenic and nonpathogenic fungal conidia in the air within and outside the University Hospital in Rotterdam (The Netherlands) was begun. A. fumigatus isolates obtained from the Department of Hematology were studied for genetic relatedness by randomly amplified polymorphic DNA (RAPD) analysis. This was repeated with A. fumigatus isolates contaminating culture media in the microbiology laboratory. The density of the conidia of nonpathogenic fungi in the outside air showed a seasonal variation: higher densities were measured during the summer, while lower densities were determined during the fall and winter. Hardly any variation was found in the numbers of Aspergillus conidia. We found decreasing numbers of conidia when comparing air from outside the hospital to that inside the hospital and when comparing open areas within the hospital to the closed department of hematology. The increase in the number of patients with invasive aspergillosis could not be explained by an increase in the number of Aspergillus conidia in the outside air. The short-term presence of A. flavus can only be explained by the presence of a point source, which was probably patient related. Genotyping A. fumigatus isolates from the department of hematology showed that clonally related isolates were persistently present for more than 1 year. Clinical isolates of A. fumigatus obtained during the outbreak period were different from these persistent clones. A. fumigatus isolates contaminating culture media were all genotypically identical, indicating a causative point source. Knowledge of the epidemiology of Aspergillus species is necessary for the development of strategies to prevent invasive aspergillosis. RAPD fingerprinting of Aspergillus isolates can help to determine the cause of an outbreak of invasive aspergillosis