Indwelling time of peripherally inserted central catheters and incidence of bloodstream infections in haematology patients: a cohort study

Background

We aimed to assess whether longer indwelling time of peripherally inserted central catheters (PICC) increases risk of central line associated bloodstream infections (CLABSI) in haematology patients.

Methods

Multicentre retrospective cohort study among haematology patients receiving PICCs between 2013 and 2015. Occurrence of CLABSI based on CDC definitions was assessed. We calculated incidence rates, determined risk factors for CLABSI and used Poisson regression models to assess the risk of developing CLABSI as a function of PICC dwell time. We compared diagnoses and treatment characteristics between 2013–2015 and 2015–2020.

Results

455 PICCs placed in 370 patients were included, comprising 19,063 catheter days. Median indwelling time was 26 days (range 0–385) and CLABSI incidence was 4.0 per 1000 catheter days, with a median time to CLABSI of 33 days (range 18–158). Aplastic anaemia (AA) was associated with an increased risk of CLABSI; patients undergoing autologous stem cell transplantation (SCT) were less likely to develop CLABSI. In the unadjusted analysis, PICCs with an indwelling time of 15–28 days, 29–42 days, 43–56 days and > 56 days each had an increased CLABSI incidence rate ratio of 2.4 (1.2–4.8), 2.2 (0.95–5.0), 3.4 (1.6–7.5) and 1.7 (0.9–3.5), respectively, compared to PICCs in place for < 15 days. However, after adjusting for AA and SCT, there was no significant difference in incidence rates between dwell times (p 0.067).

Conclusions

Our study shows that risk of CLABSI does not appear to increase with longer PICC indwelling time. Routine replacement of PICCs therefore is unlikely to prevent CLABSI in this population.

Prevalence of extended-spectrum β-lactamase-producing Enterobacterales in retail sheep meat from Zagazig city, Egypt

Background

The goal of this study was to investigate the prevalence of extended-spectrum β-lactamase production in Enterobacterales isolated from retail sheep meat in Zagazig, Egypt.

Methods

One hundred random samples of sheep meat were collected from different retail butcher shops (n = 5) in the city of Zagazig, Egypt. Bacterial isolates were identified by MALDI-TOF MS and screened for antibiotic susceptibility by disk diffusion; further genotypic characterization of β-lactamase-encoding genes was performed with Real-Time PCR. E. coli strains were phylotyped with the Clermont triplex PCR method.

Results

Of the total of 101 bacterial isolates recovered from retail sheep meat samples, 93 were E. coli, six were Enterobacter cloacae and two were Proteus mirabilis. As many as 17% of these 100 samples showed ESBL phenotypes, all were E. coli. The bla_CTX-M genes were detected in seven isolates (six were bla_CTX-M-15 and one was bla_CTX-M-14), three isolates harboured bla_TEM (all were bla_TEM-one), and two carried genes of the bla_SHV family (both were bla_SHV-12). Eight E. coli isolates expressed ESBL phenotype but no bla_TEM, bla_SHV or bla_CTX-M genes were detected by PCR. ESBL- positive E. coli isolates were nearly equally distributed over the commensal groups A/B1 and the virulent group D.

Conclusion

Nearly one in five sheep meat samples was contaminated with ESBL-E. coli. This further corroborates the potential role played by contaminated meat in the increasing resistance rates that have been reported worldwide.

High Treatment Uptake in Human Immunodeficiency Virus/Hepatitis C Virus-Coinfected Patients After Unrestricted Access to Direct-Acting Antivirals in the Netherlands

Background

The Netherlands has provided unrestricted access to direct-acting antivirals (DAAs) since November 2015. We analyzed the nationwide hepatitis C virus (HCV) treatment uptake among patients coinfected with human immunodeficiency virus (HIV) and HCV.

Methods

Data were obtained from the ATHENA HIV observational cohort in which >98% of HIV-infected patients ever registered since 1998 are included. Patients were included if they ever had 1 positive HCV RNA result, did not have spontaneous clearance, and were known to still be in care. Treatment uptake and outcome were assessed. When patients were treated more than once, data were included from only the most recent treatment episode. Data were updated until February 2017. In addition, each treatment center was queried in April 2017 for a data update on DAA treatment and achieved sustained virological response.

Results

Of 23574 HIV-infected patients ever linked to care, 1471 HCV-coinfected patients (69% men who have sex with men, 15% persons who [formerly] injected drugs, and 15% with another HIV transmission route) fulfilled the inclusion criteria. Of these, 87% (1284 of 1471) had ever initiated HCV treatment between 2000 and 2017, 76% (1124 of 1471) had their HCV infection cured; DAA treatment results were pending in 6% (92 of 1471). Among men who have sex with men, 83% (844 of 1022) had their HCV infection cured, and DAA treatment results were pending in 6% (66 of 1022). Overall, 187 patients had never initiated treatment, DAAs had failed in 14, and a pegylated interferon-alfa-based regimen had failed in 54.

Conclusions

Fifteen months after unrestricted DAA availability the majority of HIV/HCV-coinfected patients in the Netherlands have their HCV infection cured (76%) or are awaiting DAA treatment results (6%). This rapid treatment scale-up may contribute to future HCV elimination among these patients.

[Bacteriophages in the battle against multidrug resistant bacteria]

Bacteriophages are viruses that infect bacteria. They are highly specific for a bacterial species. The so-called 'lytic phages' can lyse bacteria when they infect them; these phages can be used to treat bacterial infections. Despite a century of experience with phage therapy, the evidence for clinical efficacy is limited. Side effects are generally considered to be mild. The selection, preparation and administration of phages for therapy is laborious, and investigations into the clinical benefits are not easy. More research is needed, also in the face of the increasing antimicrobial resistance.

Host factors are more important in predicting recurrent Clostridium difficile infection than ribotype and use of antibiotics

OBJECTIVE

A frequent complication of Clostridium difficile infection (CDI) is recurrent disease. The aim of this study was to determine whether early recurrence risk was higher after infection with ribotype 027 (outbreak strain) compared with infection with endemic strain types of C. difficile.

METHODS

Consecutive patients diagnosed with CDI between May 2013 and March 2014 were included (outbreak strain, and non-outbreak strains). Patients who developed recurrent CDI within 30 days after completion of CDI treatment, were compared with patients without a recurrence. Medical charts were reviewed for demographic and clinical characteristics. General practitioners were contacted to complete data about the occurrence of recurrent CDI, and the use of medication after hospital discharge.

RESULTS

In total, 135 patients were at risk for the development of recurrent CDI; 74 patients were infected by ribotype 027, and 61 patients by other ribotypes. Thirty-nine patients (29%) developed recurrent CDI within 30 days after completion of CDI treatment. In multivariable analysis, age ≥70 years (HR 3.05, 95% CI 1.54-6.03), and a duration of CDI treatment ≥11 days (HR 1.92, 95% CI 1.00-3.69) were clearly associated with recurrence; infection with ribotype 027 showed a HR of 1.72 (95% CI 0.88-3.33).

CONCLUSION

During this outbreak of C. difficile in a tertiary care centre, age and a prolonged duration of CDI therapy (which is most likely a marker of underlying disease severity) were the main risk factors for recurrent CDI. This points to host factors as more important predictors for recurrent CDI than strain type or antibiotic use.

Fecal carriage of extended-spectrum β-lactamase- and carbapenemase-producing Enterobacteriaceae in Egyptian patients with community-onset gastrointestinal complaints: a hospital -based cross-sectional study

Objectives

The aim of this study was to determine the prevalence of extended-spectrum β-lactamase (ESBL) and carbapenemase production among Enterobacteriaceae isolated from ambulatory patients with gastrointestinal complaints admitted to El-Ahrar General Hospital, Zagazig, Egypt in the period between January 2013 and May 2013.

Methods

One hundred and thirteen Enterobacteriaceae isolates were recovered from 100 consecutive Egyptian patients with community–onset gastrointestinal complaints. The fecal samples were plated directly on selective EbSA-ESBL Screening Agar and on MacConkey agar. Isolate identification was performed with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Screening for ESBLs and carbapenemases production was done by both the automated VITEK®2 system with AST N198 and by disk diffusion method. Real-time PCR and sequencing were used to characterize the resistance genes. Phylogroups of the E. coli isolates were determined by a triplex PCR-based method.

Results

Of 100 patients screened for fecal colonization with extended-spectrum β-lactamase -producing Enterobacteriaceae (ESBL-E) and carbapenemase- producing Enterobacteriaceae (CPE), 68 were colonized with ESBL-E whereas five patients were positive for CPE. One hundred and thirteen Enterobacterceae isolates were recovered from 100 fecal samples, they belonged to E. coli (n = 72), Klebsiella pneumoniae (n = 23), Enterobacter cloacae(n = 3), Salmonella spp. (n = 1) and other Enterobacterceae isolates (n = 14). The bla_CTX-M gene was detected in 89.04% (65/73) of the ESBL-producing Enterobacteriaceae, whereas bla_SHV and bla_TEM were detected in 30.14% (22/73) and 19.18% (14/73) respectively. Three out of 5 carbapenem-resistant isolates harbored New Delhi metallo-beta-lactamase (NDM) and 2 produced Verona integron-encoded metallo- beta -lactamase (VIM). Twenty-two (47.83%) of the ESBL positive isolates were multidrug resistant (MDR). Phylogenetic analysis showed that, of the 51 ESBL-EC isolates, 17 belonged to group B2, 13 to group D, 11 to group A and 10 to group B1.

Conclusions

Nearly two-thirds of the Enterobacteriaceae isolates recovered from feces of ambulatory patients with community–onset gastrointestinal complaints admitted to El-Ahrar General Hospital, Zagazig, Egypt were ESBL producers and one in every 20 patients included in our study was colonized by carbapenemase-producing Enterobacteriaceae. These high colonization rates are worrying, therefore prudent antimicrobial use should be adopted in Egyptian community settings.

How to: Establish and run a stool bank

BACKGROUND

Since 2013, several stool banks have been developed following publications reporting on clinical success of 'faecal microbiota transplantation' (FMT) for recurrent Clostridium difficile infections (CDI). However, protocols for donor screening, faecal suspension preparation, and transfer of the faecal suspension differ between countries and institutions. Moreover, no European consensus exists regarding the legislative aspects of the faecal suspension product. Internationally standardized recommendations about the above mentioned aspects have not yet been established.

OBJECTIVE

In 2015, the Netherlands Donor Feces Bank (NDFB) was founded with the primary aim of providing a standardized product for the treatment of patients with recurrent CDI in the Netherlands. Standard operation procedures for donor recruitment, donor selection, donor screening, and production, storage, and distribution of frozen faecal suspensions for FMT were formulated.

RESULTS AND DISCUSSION

Our experience summarized in this review addresses current donor recruitment and screening, preparation of the faecal suspension, transfer of the faecal microbiota suspension, and the experiences and follow-up of the patients treated with donor faeces from the NDFB.

Risk factors for extended-spectrum β-lactamase-producing Escherichia coli urinary tract infection in the community in Denmark: a case-control study

OBJECTIVE

To verify the role of proton pump inhibitors (PPI) and nitrofurantoin, which have appeared as novel risk factors for carriage of extended-spectrum β-lactamase (ESBL) -producing Escherichia coli, as risk factors for ESBL E. coli urinary tract infection (UTI). We included known risk factors to ascertain whether our findings are comparable with those of previous studies.

METHODS

Population-based case-control study including 339 cases with community-onset ESBL E. coli UTI in 2007-2012, 3390 non-ESBL E. coli UTI controls and 3390 population controls. We investigated potential risk factors by estimating ORs and 95% CIs adjusting for sex, age and co-morbidity.

RESULTS

Comparing cases with non-ESBL E. coli UTI, PPI use yielded an OR of 1.6 (95% CI 1.2-2.0) and antibiotic exposure gave an OR of 1.4 (95% CI 1.1-1.8); these were driven by nitrofurantoin (OR 1.8; 95% CI 1.3-2.6) and macrolides (OR 1.7; 95% CI 1.2-2.3). Other risk factors included previous hospitalization with one or two and more than two hospitalizations versus none yielding ORs of 1.9 (95% CI 1.4-2.5) and 4.6 (95% CI 3.2-6.8), recent surgery (OR 2.0; 95% CI 1.5-2.8), renal disease (OR 2.2; 95% CI 1.4-3.4), chronic pulmonary disease (OR 1.4; 95% CI 1.0-2.0) and cancer (OR 1.5; 95% CI 1.1-2.1). Comparing cases with population controls, we found that most risk factors were also risk factors for non-ESBL UTI.

CONCLUSIONS

ESBL E. coli UTI were associated with previous hospitalization and surgery. Nitrofurantoin and macrolides augmented the risk. PPIs had a moderate effect but may be important facilitators of ESBL carriage due to their widespread use.

[Faecal microbiota transplantation: indications in perspective]

- As yet, with cure rates around 85%, recurrent Clostridium difficile infection is the only definite indication for faecal microbiota transplantation.- Faecal microbiota transplantation induces clinical remission and endoscopic improvements in 24-30% of patients with ulcerative colitis, compared to 5% (water) to 20% (autologous faeces) in placebo-treated patients. Current research focuses on the identification of 'super donors', and subgroups of patients in which faecal microbiota transplantation is effective.- In patients with metabolic syndrome, faecal microbiota transplantation may increase insulin sensitivity. Weight, body mass index, and energy metabolism are not affected by faecal microbiota transplantation in humans.- In addition to the aforementioned indications, faecal microbiota transplantation is an emerging treatment modality for patients with Crohn's disease, irritable bowel syndrome, graft-versus-host-disease, and carriage of multidrug-resistant micro-organisms. Randomized controlled trials, comparing faecal microbiota transplantation with placebo treatment, are required to determine the effectiveness of faecal microbiota transplantation in these patient groups.

Cost analysis of an outbreak of Clostridium difficile infection ribotype 027 in a Dutch tertiary care centre

BACKGROUND

The economic impact of Clostridium difficile infection (CDI) on the healthcare system is significant. From May 2013 to May 2014, an outbreak of C. difficile ribotype 027 occurred in a Dutch tertiary care hospital, involving 72 patients. The primary aim of this study was to provide insight into the financial burden that this CDI outbreak brought upon this hospital.

METHODS

A retrospective analysis was performed to estimate the costs of a one-year-long C. difficile ribotype 027 outbreak. Medical charts were reviewed for patient data. In addition, all costs associated with the outbreak control measures were collected.

FINDINGS

The attributable costs of the whole outbreak were estimated to be €1,222,376. The main contributing factor was missed revenue due to increased length of stay of CDI patients and closure of beds to enable contact isolation of CDI patients (36%). A second important cost component was extra surveillance and activities of the Department of Medical Microbiology and Infection Control (25%).

CONCLUSION

To the authors' knowledge, this is the first study to provide insight into the attributable costs of CDI in an outbreak setting, and to delineate the major cost items. It is clear that the economic consequences of CDI are significant. The high costs associated with a CDI outbreak should help to justify the use of additional resources for CDI prevention and control.

Prevalence and risk factors for carriage of ESBL-producing Enterobacteriaceae in Amsterdam

Objectives

The objectives of this study were to determine the prevalence of carriage of ESBL-producing Enterobacteriaceae (ESBL-E) in a representative sample of the general adult Dutch community, to identify risk factors and to gain understanding of the epidemiology of these resistant strains.

Methods

Adults enrolled in five general practices in Amsterdam were approached by postal mail and asked to fill in a questionnaire and to collect a faecal sample. Samples were analysed for the presence of ESBL-E. ESBL genes were characterized by PCR and sequencing. Strains were typed using MLST and amplified fragment length polymorphism (AFLP) and plasmids were identified by PCR-based replicon typing. Risk factors for carriage were investigated by multivariate analysis.

Results

ESBL-E were found in 145/1695 (8.6%) samples; 91% were Escherichia coli. Most ESBL genes were of the CTX-M group (bla_CTX-M-1 and bla_CTX-M-15). MLST ST131 was predominant and mainly associated with CTX-M-15-producing E. coli. One isolate with reduced susceptibility to ertapenem produced OXA-48. In multivariate analyses, use of antimicrobial agents, use of antacids and travel to Africa, Asia and Northern America were associated with carriage of ESBL-E, in particular strains with bla_CTX-M-14/15.

Conclusions

This study showed a high prevalence of ESBL-E carriage in the general Dutch community. Also, outside hospitals, the use of antibiotics was a risk factor; interestingly, use of antacids increased the risk of carriage. A major risk factor in the general population was travel to countries outside Europe, in particular to Asia, Africa and Northern America.

Outline of a bacterial filter-based assay to detect beta-lactamases

We describe a new phenotypic test to detect beta-lactamases. This assay is based on diffusion of beta-lactam/beta-lactamase through a bacterial filter. Beta-lactam hydrolysis on (the other side of) the filter leads to a change in antibiotic susceptibility, which can be measured by disc diffusion tests. We illustrate its ease of use to detect beta-lactamases of different classes.

Extended-Spectrum β-Lactamases and/or Carbapenemases-Producing Enterobacteriaceae Isolated from Retail Chicken Meat in Zagazig, Egypt

OBJECTIVES

The aim of the present study was to determine the prevalence and to characterize extended-spectrum β-lactamases- and/or carbapenemases-producing Enterobacteriaceae among Enterobacteriaceae isolated from retail chicken meat in Zagazig, Egypt.

METHODS

One hundred and six Enterobacteriaceae isolates were collected from retail chicken meat samples purchased in Zagazig, Egypt in 2013. Species identification was done by MALDI-TOF MS. Screening for ESBL-E was performed by inoculation of isolates recovered from meat samples onto the EbSA (Cepheid Benelux, Apeldoorn, the Netherlands) selective screening agar. ESBL production was confirmed by combination disc diffusion test with clavulanic acid (Rosco, Taastrup, Denmark). Carbapenemases production was confirmed with double disk synergy tests. Resistance genes were characterized by PCR with specific primers for TEM, SHV, and CTX-M and carbapenemases (KPC, NDM, OXA-48, IMP and VIM). PCR products of CTX-M genes were purified and sequenced. Phylogenetic grouping of E. coli was performed by a PCR-based method.

RESULTS

Of these 106 isolates 69 (65.09%) were ESBL producers. Twelve (11.32%) of these isolates were also phenotypically class B carbapenemases producer. TEM genes were detected in 61 (57.55%) isolates. 49 (46.23%) isolates harbored CTX-M genes, and 25 (23.58%) carried genes of the SHV family. All CPE belonged to the NDM group. The predominant CTX-M sequence type was CTX-M-15 (89.80%). The majority (80%) of the ESBL-EC belonged to low virulence phylogroups A and B1.

CONCLUSIONS

This is the first study from Egypt reporting high rates of ESBLs and carbapenemases (65.09% and 11.32%, respectively) in Enterobacteriaceae isolated from retail chicken meat. These results raise serious concerns about public health and food safety as retail meat could serve as a reservoir for these resistant bacteria which could be transferred to humans through the food chain.

Extended-Spectrum β-Lactamase- and Carbapenemase-Producing Enterobacteriaceae Isolated from Egyptian Patients with Suspected Blood Stream Infection

Objectives

The aim of the study was to investigate the prevalence of extended-spectrum β-lactamase and carbapenemase production among Enterobacteriaceae isolated from Egyptian patients with suspected blood stream infection.

Methods

Ninety-four Enterobacteriaceae blood culture isolates from Egyptian patients with suspected blood stream infection were collected, one isolate per patient. Identification of bacterial isolates was performed with MALDI-TOF (MS-based Vitek MS system, bioMerieux). Screening for ESBLs and carbapenemases production was done with the Vitek 2 system (bioMérieux). ESBL production was confirmed using the combined disk diffusion method for cefotaxime, ceftazidime, and cefepime, all with and without clavulanic acid (Rosco). Real-time PCR and sequencing were used to characterize the resistance genes. The phylogenetic groups of E. coli were identified by a PCR-based method.

Results

Of the 94 Enterobacteriaceae isolates 46 (48.93%) showed an ESBL phenotype. One Enterobacter spp isolate was ESBL-producer and meropenem-resistant. The genetic analysis showed that CTX-M was present in 89.13% (41/46) of the ESBL-producing Enterobacteriaceae, whereas TEM and SHV were detected in 56.52% (26/46) and 21.74% (10/46) respectively (47.83%) of the ESBL-producing isolates were multidrug resistant (MDR). Eleven out of 30 ESBL-producing E-coli isolates were assigned to phylogroup B2, followed by groups B1 (8 isolates), A (6 isolates) and D (5 isolates).

Conclusions

The high ESBL-E rates (48.93%) found in this study together with the identification of one carbapenem-resistant Enterobacter spp isolate is worrisome. Our results indicate that systems for monitoring and detection of ESBL-producing bacteria in Egyptian hospitals have to be established. Also strict hospital infection control policies with the restriction of the consumption of extended-spectrum cephalosporins are necessary.

Prevalence of ESBL-producing Enterobacteriaceae in raw vegetables

To determine whether extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) are present in retail raw vegetables in Amsterdam, the Netherlands, we collected 119 samples of 15 different types of vegetables from various sources. After culture, strain identification and susceptibility testing, ESBL-encoding genes were characterised by a microarray. Four of the 15 vegetable types were contaminated with ESBL-E. Seven samples (6 %) yielded ESBL-E. Three bla_CTX-M-15, one bla_CTX-M-1, two genes of the CTX-M-9 group and one SHV ESBL-encoding gene were found. The ESBL genes were similar to what is found in enterobacterial strains from human origin. Therefore, raw vegetables might be a source of resistance genes for the enterobacterial strains found in humans.

Dutch guideline on the laboratory detection of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has rapidly emerged worldwide, affecting both healthcare and community settings, and intensive livestock industry. The efficient control of MRSA strongly depends on its adequate laboratory detection. This guideline provides recommendations on the appropriate use of currently available diagnostic laboratory methods for the timely and accurate detection of MRSA in patients and healthcare workers. Herewith, it aims to standardise and improve the diagnostic laboratory procedures that are used for the detection of MRSA in Dutch medical microbiology laboratories.

Rapid diagnostic testing of methicillin-resistant Staphylococcus aureus carriage at different anatomical sites: costs and benefits of less extensive screening regimens

Multiple body site screening and pre-emptive isolation of patients at risk for methicillin-resistant Staphylococcus aureus (MRSA) carriage are considered essential for control of nosocomial spread. The relative importance of extranasal screening when using rapid diagnostic testing (RDT) is unknown. Using data from a multicentre study evaluating BD GeneOhm™ MRSA PCR (IDI), Xpert MRSA (GeneXpert) and chromogenic agar, added to conventional cultures, we determined cost-effectiveness assuming isolation measures would have been based on RDT results of different hypothetical screening regimes. Costs per isolation day avoided were calculated for regimes with single or less extensive multiple site RDT, regimes without conventional back-up cultures and when PCR would have been performed with pooling of swabs. Among 1764 patients at risk, MRSA prevalence was 3.3% (n = 59). In all scenarios the negative predictive value is above 98.4%. With back-up cultures of all sites as a reference, the costs per isolation day avoided were €15.19, €30.83 and €45.37 with 'nares only' screening using chromogenic agar, IDI and GeneXpert, respectively, as compared with €19.95, €95.77 and €125.43 per isolation day avoided when all body sites had been screened. Without back-up cultures costs per isolation day avoided using chromogenic agar would range from €9.24 to €76.18 when costs per false-negative RDT range from €5000 up to €50 000; costs for molecular screening methods would be higher in all scenarios evaluated. In conclusion, in a low endemic setting chromogenic agar screening added to multiple site conventional cultures is the most cost-effective MRSA screening strategy.

Prevalence of methicillin-resistant Staphylococcus aureus and risk factors for carriage in Dutch hospitals

To evaluate the actual burden of methicillin-resistant Staphylococcus aureus and determine risk factors for carriage and infection, we performed a prevalence survey with a nested case-control study among inpatients in Dutch hospitals. The prevalence of carriage was 0.94 cases per 1,000 inpatients, and the prevalence of infection was 0.21 cases per 1,000 inpatients. Professional contact with livestock and a stay in a foreign hospital were associated with carriage.

Five-minute Giemsa stain for rapid detection of malaria parasites in blood smears

The Giemsa stain is used as the gold standard for the diagnosis of malaria on blood smears. The classical staining procedure requires between 30 and 45 min. We modified the Giemsa stain and reduced the staining time to 5 min without any loss of quality.

IS-pro: high-throughput molecular fingerprinting of the intestinal microbiota

The human intestinal microbiota is known to play an important role in human health and disease, and with the advent of novel molecular techniques, disease-specific variations in its composition have been found. However, analysis of the intestinal microbiota has not yet been applicable in large-scale clinical research or routine diagnostics because of the complex and expensive nature of the techniques needed. Here, we describe a new PCR-based profiling technique for high-throughput analysis of the human intestinal microbiota, which we have termed IS-pro. This technique combines bacterial species differentiation by the length of the 16S-23S rDNA interspace region with instant taxonomic classification by phylum-specific fluorescent labeling of PCR primers. We validated IS-pro in silico, in vitro, and in vivo, on human colonic biopsies and feces, and introduced a standardized protocol for data analysis. IS-pro is easy to implement in general clinical microbiological laboratories with access to capillary gel electrophoresis, and the high-throughput nature of the test makes analysis of large numbers of samples feasible. This combination renders IS-pro ideally suited for use in clinical research and routine diagnostics.

[Optimisation of the antibiotic policy in the Netherlands. XII. The SWAB guideline for antimicrobial eradication of MRSA in carriers]

The 'Stichting Werkgroep Antibioticabeleid' (SWAB; Dutch Working Party on Antibiotics Policy) has developed evidence-based guidelines for the antimicrobial treatment of methicillin-resistant Staphylococcus aureus (MRSA) carriers for the eradication of MRSA. A distinction was made between uncomplicated and complicated carriage depending on the presence or absence of an active MRSA infection, skin lesions, foreign body material, mupirocin resistance and/or extranasal carriage. The indication for treatment is determined by the consequences of carriage for the carrier and his/her environment, the adverse events of treatment, and the likelihood of a successful treatment. The first choice of treatment in uncomplicated carriers is a combination of mupirocin nasal ointment and disinfectant soap for 5 days, along with hygiene advice. If treatment fails, sources in the vicinity of the patient must be sought. Complicated carriers receive a combination of 2 oral antibiotics, in addition to mupirocin nasal ointment and disinfectant soap, for at least 7 days.

[Horizontal transfer of bacterial genes and its significance for antibiotic resistance and pathogenicity]

* Sexual reproduction does not occur in bacteria. The point of departure in bacterial reproduction is always that one individual divides itself into two identical descendants. * In the bacterial world, however, there is certainly exchange of hereditary characteristics (DNA). This type of exchange is called horizontal gene transfer. * There are 3 basic ways for the exchange of DNA between bacteria: conjugation, transduction and natural transformation. Each of these has its specific impact on the species. * During conjugation, a piece of DNA is copied in one bacterium and transferred to another via a temporary connection, a conjugative pilus. In this way, for example, a particular gene that codes for resistance against antibiotics can be transmitted. * In transduction, the transfer of DNA takes place with the aid of bacteriophages. The gene that codes for the toxin produced by Vibrio cholerae is spread by transduction. * In transformation, DNA that is located outside the cell is fragmented and imported into the cell, after which, via recombination, the DNA replaces a piece of original DNA in the chromosome of the host. Transformation is responsible for, among other things, antigen variation in the pneumococcal capsule. Antigen variation helps the pneumococci to resist the immune response leading to the forming of antibodies and adequate opsonisation.

Mannose-binding lectin (MBL) genotype in relation to risk of nosocomial infection in pre-term neonates in the neonatal intensive care unit

Mannose-binding lectin (MBL) plays an important role in the innate immune response. Three alleles in the MBL gene, and one allele of the promoter, independently cause low serum MBL levels as compared with the wild-type. This study investigated the relationship between MBL genotype and the occurrence of nosocomial infection among neonates in a neonatal intensive care unit (NICU). Prospectively gathered information concerning nosocomial infection was available for 742 neonates from a recently performed surveillance study in an NICU. DNA was isolated from Guthriecards for a subgroup of 204 neonates who stayed in the NICU for > or =4 days. After a pre-PCR for the MBL gene in blood spots on Guthriecards, mutations were analysed by real-time PCR to detect six mutations in the MBL gene. An MBL genotype could be determined for 186 neonates. As compared to term neonates, genotypes encoding MBL-deficient haplotypes were significantly more prevalent among pre-term neonates. Forty-one of these neonates developed sepsis, with blood cultures yielding coagulase-negative staphylococci in 25 cases. Pneumonia occurred in 30 cases, with various causative organisms. No relationship was found between MBL genotype and the risk of nosocomial sepsis or pneumonia, even after correction for birth-weight, perhaps because of an insufficient correlation between genotype and the concentration of functional MBL. In addition, most bloodstream infections in the NICU were caused by coagulase-negative staphylococci, to which MBL binds poorly.

Levofloxacin vs. ciprofloxacin plus phenethicillin for the prevention of bacterial infections in patients with haematological malignancies

An open-label randomised clinical trial was designed to compare the efficacy and tolerance of levofloxacin and ciprofloxacin plus phenethicillin for the prevention of bacterial infections in patients with high-risk neutropenia, and to monitor the emergence of antimicrobial resistance. Adult patients (n = 242) scheduled to receive intensive treatment for haematological malignancies were assigned randomly to receive oral prophylaxis with either levofloxacin 500 mg once-daily (n = 122), or ciprofloxacin 500 mg twice-daily plus phenethicillin 250 mg four-times-daily (n = 120). The primary endpoint was failure of prophylaxis, defined as the first occurrence of either the need to change the prophylactic regimen or the initiation of intravenous broad-spectrum antibiotics. This endpoint was observed in 89 (73.0%) of 122 levofloxacin recipients and in 85 (70.8%) of 120 ciprofloxacin plus phenethicillin recipients (RR 1.03, 95% CI 0.88-1.21, p 0.71). No differences were noted between the two groups with respect to secondary outcome measures, including time to endpoint, occurrence of fever, type and number of microbiologically documented infections, and administration of intravenous antibiotics. A questionnaire revealed that levofloxacin was tolerated significantly better than ciprofloxacin plus phenethicillin. Surveillance cultures indicated the emergence of viridans group (VG) streptococci resistant to levofloxacin in 17 (14%) of 122 levofloxacin recipients; in these cases, the prophylactic regimen was adjusted. No bacteraemia with VG streptococci occurred. It was concluded that levofloxacin and ciprofloxacin plus phenethicillin are equally effective in the prevention of bacterial infections in neutropenic patients, but that levofloxacin is tolerated better. Emergence of levofloxacin-resistant VG streptococci is of concern, but appears to be a manageable problem.

[Methicillin-resistant Staphylococcus aureus (MRSA) in the community]

Methicillin-resistant Staphylococcus aureus (MRSA) infections have been confined to healthcare centres for decades. However, MRSA infections are increasingly seen in young healthy individuals with no exposure to healthcare centres. These community-acquired MRSA (CA-MRSA) strains differ from healthcare-associated MRSA (HA-MRSA) strains in various ways. For example, CA-MRSA is strongly associated with the staphylococcal cassette chromosome mec (SCCmec) type IV and the toxin Panton-Valentine leukocidin. CA-MRSA spreads relatively easily but often remains susceptible to non-3-lactam antibiotics. Given the epidemic potential of CA-MRSA strains, there is a high probability that the number of CA-MRSA infections will increase in The Netherlands. In order to prevent and control CA-MRSA outbreaks in the community successfully, the restrictive Dutch antibiotic policy must be followed with strict infection prevention measures.

How many infection control staff do we need in hospitals?

During a one-day workshop experienced infection control practitioners (ICPs) and medical microbiologists debated how much time was needed for the delivery of infection control activities in a model hospital. They agreed a standard of one full-time equivalent (FTE) ICP per 178 hospital beds and one FTE medical microbiologist per 806 hospital beds. This is 40% and 24% more than the usual standard, respectively. Now that official numbers of hospital beds have become an inadequate parameter for work delivered by hospitals, a new standard is proposed, with the number of admissions as the denominator. This is one FTE ICP per 5000 admissions and one medical microbiologist or epidemiologist per 25000 admissions.

[Methicillin-resistant Staphylococcus aureus in pig breeders and cattle breeders]

It was recently observed that pig breeders in The Netherlands often carry methicillin-resistant Staphylococus aureus (MRSA). These MRSA strains are related to MRSA strains found in pigs. A case-control study showed that not only pig breeders but also cattle breeders are at risk of carrying MRSA. It is advised to keep pig breeders, if they are admitted to a hospital, in isolation until surveillance cultures are proven negative. This also applies to veterinarians and slaughterhouse personnel. For cattle breeders screening without isolation on admission to a hospital is sufficient.

Public health impact of isoniazid-resistant Mycobacterium tuberculosis strains with a mutation at amino-acid position 315 of katG: a decade of experience in The Netherlands

A previous limited study demonstrated that Mycobacterium tuberculosis isolates with a mutation at amino-acid position 315 of katG (Delta315) exhibited high-level resistance to isoniazid and were more frequently resistant to streptomycin. In the present study, isoniazid-resistant M. tuberculosis isolates from 8,332 patients in The Netherlands (1993-2002) were screened for the Delta315 mutation. Isoniazid resistance was found in 592 (7%) isolates, of which 323 (55%) carried Delta315. IS6110 restriction fragment length polymorphism analysis showed that Delta315 isolates occurred in clusters, suggesting recent transmission, at the same frequency as isoniazid-susceptible isolates. In contrast, other isoniazid-resistant isolates clustered significantly less frequently. Delta315 isolates were high-level isoniazid-resistant, streptomycin-resistant and multidrug-resistant significantly more often, and may have a greater impact on public health, than other isoniazid-resistant isolates.

[A boy with cholera from India]

A 7-year-old Indian boy travelling from India to the United Kingdom was brought to the Emergency Clinic of Airport Medical Services at Schiphol airport in Amsterdam, the Netherlands. He had had watery diarrhoea in the aircraft and had lost consciousness. In view of the strong indications for cholera and the rice water-like diarrhoea, he was admitted to the paediatric ward of the VU Medical Centre where intravenous rehydration was carried out. He recovered within three days. A large number of comma-shaped, motile, Gram-negative rods were found in the faeces. After two days, the faeces culture revealed Vibrio cholerae O1 El Tor, serotype Inaba. On the day of the flight, the patient had drunk a litre of water from a bottle that later turned out to have been from the New Delhi water supply. Cholera is rare as an import disease in the Netherlands. Due to the severe dehydration, the infection can run a serious course and even be fatal. The infection is not transmitted from person to person. Therefore, no special measures are needed when a patient with cholera is admitted to hospital.

Class 1 integrons in ciprofloxacin-resistant Escherichia coli strains from two Dutch hospitals

A significant increase in the isolation frequency of ciprofloxacin-resistant Escherichia coli was observed in the haematology departments of two university hospitals in The Netherlands. Amplified fragment length polymorphism analysis revealed that this increase was not caused by the emergence of unique ciprofloxacin-resistant clones. Determination of the presence of class 1 integrons indicated that 81% of the ciprofloxacin-resistant isolates contained an intI1 gene, compared with 11% of the ciprofloxacin-susceptible isolates (p<0.0001). The quinolone resistance gene qnrA was not present in any of the integrons characterised and could not be detected using dot-blot hybridisation of total DNA. In addition, conjugation experiments showed that ciprofloxacin resistance was not co-transferred with class 1 integrons. Ciprofloxacin-resistant isolates harboured mutations in the gyrA gene, which are known to encode ciprofloxacin resistance. In conclusion, an association was observed between ciprofloxacin resistance and the presence of class 1 integrons, which could not be explained by the currently known genetic determinants of quinolone resistance.

Nosocomial infections in a Dutch neonatal intensive care unit: surveillance study with definitions for infection specifically adapted for neonates

The incidence of nosocomial infection in neonatal intensive care units (NICUs) is high compared with other wards. However, no definitions for hospital-acquired infection are available for NICUs. The aim of this study was to measure the incidence of such infections and to identify risk factors in the NICU of the VU University Medical Center, which serves as a level III regional NICU. For this purpose, a prospective surveillance was performed in 1998-2000. We designed definitions by adjusting the current definitions of the Centers for Disease Control and Prevention (CDC) for children <1 year of age. Birth weight was stratified into four categories and other baseline risk factors were dichotomized. Analysis of risk factors was performed by Cox regression with time-dependent variables. The relationship between the Clinical Risk Index for Babies (CRIB) and nosocomial infection was investigated. Furthermore, for a random sample of cases, we determined whether bloodstream infection and pneumonia would also have been identified with the CDC definitions. Seven hundred and forty-two neonates were included in the study. One hundred and ninety-one neonates developed 264 infections. Bloodstream infection (N=138, 14.9/1000 patient-days) and pneumonia (N=69, 7.5/1000 patient-days) were the most common infections. Of bloodstream infections, 59% were caused by coagulase-negative staphylococci; in 21% of neonates, blood cultures remained negative. In 25% of pneumonias, Enterobacteriaceae were the causative micro-organisms; 26% of cultures remained negative. Compared with the Nosocomial Infections Surveillance System (NNIS) of the CDC, our device utilization ratios and device-associated nosocomial infection rates were high. The main risk factors for bloodstream infection were birth weight [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.45-2.17] and parenteral feeding with hospital-pharmacy-produced, all-in-one mixture 'Minimix' (HR 3.69, 95%CI 2.03-6.69); administration of intravenous antibiotics (HR 0.39, 95%CI 0.26-0.56) was a protective risk factor. The main risk factors for pneumonia were low birth weight (HR 1.37, 95%CI 1.01-1.85) and mechanical ventilation (HR 9.69, 95%CI 4.60-20.4); intravenous antibiotics were protective (HR 0.37, 95%CI 0.21-0.64). In a subcohort of 232 very-low-birthweight neonates, the CRIB was not predictive for infection. With the CDC criteria, only 75% (21/28) of bloodstream infections and 87.5% of pneumonias (21/24) would have been identified. In conclusion, our local nosocomial infection rates are high compared with those of NICUs participating in the NNIS. This can be partially explained by: (1) the use of our definitions for nosocomial infection, which are more suitable for this patient category; and (2) the high device utilization ratios.

Optimal sampling time after preparation of platelet concentrates for detection of bacterial contamination by quantitative real-time polymerase chain reaction

BACKGROUND AND OBJECTIVES

A universal quantitative real-time polymerase chain reaction (PCR), based on bacterial 16S rDNA, to detect bacterial contamination of platelet concentrates (PCs), was developed previously and compared with automated culturing. In the present study, this real-time PCR method was evaluated to determine the optimal sampling time for screening of bacterial contamination in PCs.

MATERIALS AND METHODS

Routinely prepared PCs were spiked with suspensions of Escherichia coli, Bacillus cereus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Propionibacterium acnes to 1, 10 and 100 colony-forming units (CFU)/ml and stored at room temperature for 7 days. The presence of bacteria in these PCs was monitored by quantitative real-time PCR. As a reference method (additional control), BacT/Alert automated culturing was used. For PCR, 1-ml aliquots were drawn from all (spiked) PCs on days 0, 1, 2, 3, 6 and 7 of storage. As a control, triplicate samples (10 ml) were inoculated into aerobic and anaerobic BacT/Alert culture bottles immediately after spiking (day 0) and after storage for 1, 2, 3, 6 or 7 days.

RESULTS

With quantitative real-time PCR, all bacterial species tested were reproducibly detected on day 1 after spiking at original concentrations of 10 and 100 CFU/ml. Bacteria were also detected on day 1 from PCs spiked with an initial concentration of 1 CFU/ml, except for E. coli, which was detected in only one of the three samples and P. aeruginosa, for which analysis was not performed on day 1. With the reference method, bacteria were detected in culture bottles (inoculated on day 0) within a mean time of 20.1 h, with the exception of P. acnes which was detected at a mean time of 102.3 and 49.3 h (for original spiking concentrations of 10 and 100 CFU/ml respectively).

CONCLUSIONS

PCR enables the rapid detection of low initial numbers of bacteria in PCs. For reliable detection, our results support that sampling of PCs for real-time PCR screening should not be carried out earlier than 1 day after preparation (48 h after blood collection). Importantly, the real-time PCR approach has the potential to be used before the release of PCs from the blood centre or shortly before they are transfused in the hospital.

Amplified-fragment length polymorphism analysis of Propionibacterium isolates implicated in contamination of blood products

Propionibacterium acnes is implicated in most cases of bacterial contamination of platelet concentrates (PCs). To determine the source of contamination, amplified-fragment length polymorphism (AFLP) analysis was applied. This DNA fingerprinting technique was used to study the molecular relationship of 44 isolates derived from 22 PCs and 22 corresponding red blood cells concentrates (RBCs) from the same whole blood donations. The AFLP results together with sequencing analysis of the 1,200 bp of the 16S ribosomal RNA gene revealed the existence of three main groups: two groups (groups 2 and 3) (55%) consisted of isolates that did not originate from skin flora and another group (group 1) (45%) comprised bacteria belonging to the skin flora. This latter group showed complete homology with reference strains of P. acnes. Therefore these isolates can be considered as P. acnes strains. In contrast, contaminants from groups 2 and 3 were shown to be molecularly unrelated to the P. acnes found on the skin surface. The AFLP is reproducible and gave invaluable information about the nature of Propionibacteria contaminating PCs. To gain more insights into the source of contamination, this technique could be exploited in further studies to determine the molecular relationship of different bacteria commonly found in blood products.

[Resistant microorganisms in patients transferred from foreign hospitals]

OBJECTIVE

To determine the prevalence of carriers of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and gentamicin-resistant Gram-negative bacilli (GGNB) in patients repatriated from foreign hospitals to The Netherlands.

DESIGN

Determination of prevalence.

METHOD

In the period May 1998-August 2001, 1167 patients were repatriated. Swab specimens, demographic data and clinical data were obtained during the transfer.

RESULTS

The prevalence of carriers of resistant microorganisms was 18.2%. MRSA was carried by 2.7% of the total repatriated group and by 4.7% of patients transferred to a Dutch hospital. Risk factors were antimicrobial treatment (odds ratio (OR): 3.4; 95% CI: 1.2-9.7), length of stay in a foreign hospital > or = 14 days (OR: 5.4; 95% CI: 2.3-12) and artificial ventilation (OR: 8.5; 95% CI: 1.8-41). VRE and GGNB were isolated from 2.7% and 14.1% of patients, respectively. Transfer from Asia or southern, south-eastern and eastern Europe were risk factors for carrying GGNB.

CONCLUSION

Carriership of resistant microorganisms was high among repatriated patients. The highest risk of GGNB was more closely associated with the country from which the patient was transferred than the antimicrobial treatment received in the foreign hospital.

Long-term acid suppression by omeprazole in gastro-oesophageal reflux disease patients does not lead to anti-gastric autoantibody production

BACKGROUND

Helicobacter pylori-associated atrophy of the gastric corpus is associated with the presence of anti-canalicular autoantibodies. Also, long-term profound acid suppression in H. pylori-infected subjects may cause atrophic corpus gastritis.

AIM

To investigate whether long-term acid suppression by omeprazole leads to antigastric autoantibodies.

METHODS

Fifty patients, of which 34 H. pylori-positive on entry of the study, were treated with omeprazole (20-40 mg once daily) for reflux oesophagitis, and were evaluated for anti-gastric autoantibody responses by immunohistochemistry before and after treatment. H. pylori was not eradicated and patients were followed for an average of 6.6 years (range 3-14.1 years). In addition to immunohistochemistry, anti-H(+), K(+)-ATPase reactivity was assessed by Western blot in paired sera of 41 patients (26 H. pylori-positive and 15 uninfected) and results are critically evaluated.

RESULTS

In immunohistochemistry, all patients were negative for anti-canalicular autoantibodies when omeprazole therapy started, except for two patients with corpus-predominant gastritis in the presence of H. pylori. One patient, who was H. pylori-negative, newly developed an anti-canalicular antibody response during therapy.

CONCLUSIONS

Our results indicate that, as compared with non-infected patients, long-term profound acid suppression therapy in H. pylori-infected gastro-oesophageal reflux disease patients does not increase or accelerate gastric autoimmunity.

Low prevalence of methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission in the Netherlands: the value of search and destroy and restrictive antibiotic use

In the Netherlands, less than 1% of clinical isolates of Staphylococcus aureus are methicillin-resistant (MRSA). A national search and destroy policy prevents MRSA from becoming endemic. Some MRSA outbreaks cannot be related to patients at risk for MRSA carriage. This study was designed to measure the prevalence of MRSA among patients without risk factors for MRSA carriage at the time of admission to the hospital. In four Dutch hospitals, patients admitted to non-surgical departments in the period 1999-2000 were screened for MRSA nasal carriage. Nasal swabs were streaked on 5% sheep blood agar (BA), submerged in a selective broth, and incubated for two to three days at 35 degrees C. Colonies suspected of being S. aureus were identified with an agglutination test. Susceptibility testing was performed by an automated system and additional oxacillin disk diffusion. Methicillin resistance was confirmed by a DNA hybridization test and mecA PCR. MRSA strains were genotyped by pulsed-field gel electrophoresis (PFGE). Twenty-four percent (2332/9859) of the patients were S. aureus nasal carriers. Only three (0.03%) patients were MRSA carriers. These patients were not repatriated, nor known to be MRSA carriers before screening. Genotyping revealed that the strains were not clonally related and were not related to MRSA outbreaks in the hospital where the patients were admitted. We conclude that at routine admission to a Dutch hospital (excluding high-risk foreign admissions) the MRSA prevalence is low (0.03%), due to the Dutch search and destroy policy and restrictive antibiotic prescribing.

Pharmacokinetics and effects on bowel and throat microflora of oral levofloxacin as antibacterial prophylaxis in neutropenic patients with haematological malignancies

Gram-positive breakthrough infections pose a major drawback to the use of quinolones for antibacterial prophylaxis in neutropenic patients. Levofloxacin offers the advantage of an augmented Gram-positive spectrum and may potentially overcome this problem. In an open-label, clinical pilot study, we investigated the effects on throat and bowel microflora and pharmacokinetics of a once-daily oral dose of 500 mg levofloxacin, during neutropenia in 20 patients with haematological malignancies. Gram-negative bowel flora and Staphylococcus aureus were successfully eradicated. No Gram-negative infections occurred. Minimal inhibitory concentration values for viridans group (VG) streptococci tended to increase, in four patients over 8 mg/l, indicating resistance to levofloxacin. Four patients developed blood-stream infections with levofloxacin-resistant Gram-positive cocci. No significant changes in numbers of anaerobic microorganisms were observed. Pharmacokinetic parameters of levofloxacin, including the maximum serum concentration (C(max)), time to C(max) (T(max)), area under the concentration-time curve (AUC), volume of distribution at steady state (V(ss)/F) and clearance (CL/F) were not statistically different at first dose and during neutropenia. In conclusion, levofloxacin eradicates Gram-negative microorganisms and S. aureus and spares the anaerobic flora. Its pharmacokinetic profile is unaltered during neutropenia. However, prolonged administration of levofloxacin as antibacterial prophylaxis may be hampered by the emergence of levofloxacin-resistant VG streptococci.

Effect of frequent consumption of a Lactobacillus casei-containing milk drink in Helicobacter pylori-colonized subjects

BACKGROUND

Several studies have reported inhibitory effects of lactic acid bacteria on bacterial pathogens.

AIM

To test whether a drink containing Lactobacillus casei strain Shirota inhibits Helicobacter pylori growth.

METHODS

The in vitro growth inhibition of H. pylori was studied when L. casei was added to plates previously inoculated with H. pylori reference strain NCTC 11637. In an intervention study, 14 H. pylori-positive subjects were given Yakult drink (10(8) colony-forming units/mL L. casei) thrice daily during meals for 3 weeks. Six untreated H. pylori-positive subjects served as controls. H. pylori bacterial loads were determined using the 13C-urea breath test, which was performed before and 3 weeks after the start of L. casei supplementation.

RESULTS

In vitro, L. casei inhibits H. pylori growth. This effect was stronger with L. casei grown in milk solution than in DeMan-Rogosa-Sharpe medium. No growth inhibition was shown with medium inoculated with lactic acid, Escherichia coli strain DH5alpha or uninoculated medium. Filtration of L. casei culture before incubation with H. pylori completely abolished the inhibitory effect. Urease activity decreased in nine of the 14 (64%) subjects with L. casei supplementation and in two of the six (33%) controls (P = 0.22).

CONCLUSIONS

Viable L. casei are required for H. pylori growth inhibition. This does not result from changes in lactic acid concentration. In addition, a slight, but non-significant, trend towards a suppressive effect of L. casei on H. pylori in vivo may exist.

Alterations in penicillin-binding protein 1A confer resistance to beta-lactam antibiotics in Helicobacter pylori

Most Helicobacter pylori strains are susceptible to amoxicillin, an important component of combination therapies for H. pylori eradication. The isolation and initial characterization of the first reported stable amoxicillin-resistant clinical H. pylori isolate (the Hardenberg strain) have been published previously, but the underlying resistance mechanism was not described. Here we present evidence that the beta-lactam resistance of the Hardenberg strain results from a single amino acid substitution in HP0597, a penicillin-binding protein 1A (PBP1A) homolog of Escherichia coli. Replacement of the wild-type HP0597 (pbp1A) gene of the amoxicillin-sensitive (Amx(s)) H. pylori strain 1061 by the Hardenberg pbp1A gene resulted in a 100-fold increase in the MIC of amoxicillin. Sequence analysis of pbp1A of the Hardenberg strain, the Amx(s) H. pylori strain 1061, and four amoxicillin-resistant (Amx(r)) 1061 transformants revealed a few amino acid substitutions, of which only a single Ser(414)-->Arg substitution was involved in amoxicillin resistance. Although we cannot exclude that mutations in other genes are required for high-level amoxicillin resistance of the Hardenberg strain, this amino acid substitution in PBP1A resulted in an increased MIC of amoxicillin that was almost identical to that for the original Hardenberg strain.

Optimum dosage regimen of palivizumab?

Palivizumab is a humanized, monoclonal antibody used to protect at-risk infants against respiratory syncytial virus (RSV) infection. The regular dosage scheme causes a low initial trough level and accumulation of the antibody after subsequent injections. Using a simple pharmacokinetic model, the authors devised an alternative dosage regimen that might correct these problems while cutting costs by 35%. To spare health care budgets, dosage schemes for future monoclonal antibodies must be chosen carefully.

[Universal vaccination against group C meningococci and pneumococci; advice from the Health Council of the Netherlands]

A committee of the Health Council of the Netherlands recently advised the Minister of Health on nationwide vaccination against group-C meningococci and pneumococci. They recommended the introduction of both vaccines into the national vaccination programme. The meningococcal C vaccine should be introduced as soon as possible, and the pneumococcal vaccine should be introduced as soon as a combined vaccine against diphtheria, tetanus, pertussis and polio and H. influenzae type B is available. In the meantime, due to various clusters of meningococcal disease caused by Neisseria meningitidis C in the Netherlands, parents have started to have their children vaccinated by buying vaccines and asking their general practitioners to perform the vaccination. This unfavourable situation must be controlled by the government through clear publicity to parents and healthcare workers.

Concurrence of hepatitis B surface antibodies and surface antigen: implications for postvaccination control of health care workers

Among 1081 persons testing positive for hepatitis B surface antigen, 106 (10%) tested positive for antibodies to surface antigen (anti-HBs) in the same blood sample. Thirty of these persons were studied in detail: seven tested positive for hepatitis B e-antigen, nine were apparently healthy blood donors, and in 14 chronic infection could be demonstrated in follow-up samples. Frozen samples of 14 persons were available for additional quantitative anti-HBs testing using another anti-HBs assay: three showed no anti-HBs reactivity, seven showed borderline anti-HBs levels (1-5 IU/L), and anti-HBs titres ranged from 23 to 66 IU/L in four HBsAg-positive persons, including an apparently healthy blood donor. Thus, after hepatitis B vaccination of medical personnel, presence of anti-HBs may erroneously suggest immunity, while in fact chronic infection with hepatitis B virus is present.