Impact of same-day antibiotic susceptibility testing on time to appropriate antibiotic treatment of patients with bacteraemia: a randomised controlled trial.

Inadequate therapy in bloodstream infections is suggested to be associated with higher mortality. We evaluated the reduction in inappropriate antibiotic therapy using rapid identification and antibiotic susceptibility testing (FAST) compared to standard of care (SOC) testing in patients with bloodstream infections. The FAST method used polymerase chain reaction (PCR) for identification and to detect growth in the presence or absence of antibiotics after only 6 h. For SOC testing, the BD Phoenix system was used. Patients with blood cultures growing Staphylococcus, Streptococcus or Enterococcus species or Gram-negative rods were randomised for FAST or SOC tests. A total of 129 patients were randomised for FAST and 121 patients for the SOC group. At the time SOC results became available, 78 patients in the FAST group could have been switched to more appropriate therapy. Although FAST results were highly accurate (agreement with SOC was 94%), they were only implemented in a minority (16) of patients. However, significantly fewer patients in the FAST group used inappropriate therapy at the time of SOC results (p = 0.025). The time to results in the FAST group was reduced by 15.6 h (p < 0.001). In the patients switched after FAST, this was done after a mean of 42.3 h compared to 61.4 h in those switched after SOC tests (p < 0.001). In bacteraemic patients, FAST resulted in significantly more patients using appropriate antibiotic therapy at the time SOC results were available and 15.6 h earlier than SOC tests. However, the implementation of FAST results was not optimal and no benefit on clinical outcome was shown.

Comparison of three different techniques for the isolation of viral RNA in sputum.

BACKGROUND: Respiratory infections are a major cause of morbidity and mortality worldwide. A high percentage of all respiratory tract infections are caused by RNA viruses. Real-time PCR is a highly sensitive method for the detection of respiratory viruses in clinical samples. A good RNA isolation protocol is of high importance, since RNA is more unstable than DNA and many clinical samples contain RNAses. OBJECTIVES: To evaluate the performance of three different RNA extraction protocols for the extraction of respiratory viral RNA from sputum samples obtained from patients with the suspicion of a viral respiratory tract infection. STUDY DESIGN: A total of 50 sputum samples, PCR positive for a respiratory RNA virus, were used for viral RNA isolation with the phenol/chloroform method, RTP(®) DNA/RNA virus mini kit and the automated MagNa Pure LC (MPLC) extraction system. After isolation, real-time PCR was performed for the detection of viral RNA in the sputum samples. RESULTS: The MPLC extraction increased the detection probability from 82% (phenol/chloroform) and 86% (RTP(®) DNA/RNA virus mini kit) to 94%. In 16% the RTP(®) DNA/RNA virus mini kit resulted in lower Ct values compared to the phenol/chloroform method, while in 32% the phenol/chloroform resulted in lower Ct values. CONCLUSIONS: The extraction of viral RNA performed with the MPLC extraction method was superior to the extraction with the RTP(®) DNA/RNA virus mini kit and to the extraction with phenol/chloroform. In general, there was no difference in the detection of viral RNA between the phenol/chloroform extraction method and the RTP(®) DNA/RNA virus mini kit.

Developments for improved diagnosis of bacterial bloodstream infections.

Bloodstream infections (BSIs) are associated with high mortality and increased healthcare costs. Optimal management of BSI depends on several factors including recognition of the disease, laboratory tests and treatment. Rapid and accurate identification of the etiologic agent is crucial to be able to initiate pathogen specific antibiotic therapy and decrease mortality rates. Furthermore, appropriate treatment might slow down the emergence of antibiotic resistant strains. Culture-based methods are still considered to be the "gold standard" for the detection and identification of pathogens causing BSI. Positive blood cultures are used for Gram-staining. Subsequently, positive blood culture material is subcultured on solid media, and (semi-automated) biochemical testing is performed for species identification. Finally, a complete antibiotic susceptibility profile can be provided based on cultured colonies, which allows the start of pathogen-tailored antibiotic therapy. This conventional workflow is extremely time-consuming and can take up to several days. Furthermore, fastidious and slow-growing microorganisms, as well as antibiotic pre-treated samples can lead to false-negative results. The main aim of this review is to present different strategies to improve the conventional laboratory diagnostic steps for BSI. These approaches include protein-based (MALDI-TOF mass spectrometry) and nucleic acid-based (polymerase chain reaction [PCR]) identification from subculture, blood cultures, and whole blood to decrease time to results. Pathogen enrichment and DNA isolation methods, to enable optimal pathogen DNA recovery from whole blood, are described. In addition, the use of biomarkers as patient pre-selection tools for molecular assays are discussed.

Mimivirus is not a frequent cause of ventilator-associated pneumonia in critically ill patients.

Acanthamoeba polyphaga mimivirus (APMV) belongs to the amoebae-associated microorganisms. Antibodies to APMV have been found in patients with pneumonia suggesting a potential role as a respiratory pathogen. In addition, positive serology for APMV was associated with an increased duration of mechanical ventilation and intensive care unit stay in patients with ventilator-associated pneumonia. The aim of the present study was to assess the presence of APMV in bronchoalveolar lavage fluid samples of critically ill patients suspected of ventilator-associated pneumonia. The study was conducted in the intensive care unit of the Maastricht University Medical Centre. All consecutive bronchoalveolar lavage fluid samples obtained between January 2005 and October 2009 from patients suspected of ventilator-associated pneumonia were eligible for inclusion. All samples were analyzed by real-time PCR targeting the APMV. A total of 260 bronchoalveolar lavage fluid samples from 214 patients (139 male, 75 female) were included. Bacterial ventilator-associated pneumonia was confirmed microbiologically in 105 out of 260 (40%) suspected episodes of ventilator-associated pneumonia (86 patients). The presence of APMV DNA could not be demonstrated in the bacterial ventilator-associated pneumonia positive or in the bacterial ventilator-associated pneumonia negative bronchoalveolar lavage fluid samples. Although suspected, APMV appeared not to be present in critically ill patients suspected of ventilator-associated pneumonia, and APMV does not seem to be a frequent cause of ventilator-associated pneumonia.

Infections with mimivirus in patients with chronic obstructive pulmonary disease.

INTRODUCTION: Antibodies against mimivirus, a recently discovered giant virus, have been found in patients presenting with pneumonia suggesting a potential role for this virus as a respiratory pathogen. Several bacterial and viral pathogens have been associated with the occurrence of acute exacerbations in COPD. However, a large part of these exacerbations have an unknown cause. In the present study we evaluated the presence of mimivirus in sputum samples of COPD patients. METHODS: From March 2009 until January 2010 all sputum samples collected during stable conditions and during exacerbations of COPD patients, referred for pulmonary rehabilitation, were included. All sputum samples were analysed by real-time PCR targeting mimivirus. Furthermore, serum samples were analysed for the presence of antibodies against mimivirus. RESULTS: A total of 220 sputum samples from 109 patients were eligible for inclusion. None of the sputum samples showed the presence of mimivirus DNA. Antibodies against mimivirus were detected in 3 serum samples from 3 patients, of which one showed an increase in antibody-titre. CONCLUSIONS: Although mimivirus was suggested as a potential respiratory pathogen, its presence could not be confirmed in the present study-population of patients with COPD.

Spread of the epidemic European fusidic acid-resistant impetigo clone (EEFIC) in general practice patients in the south of The Netherlands.

OBJECTIVES: We evaluated the susceptibility to fusidic acid, mupirocin and retapamulin of Staphylococcus aureus isolated from nasal and wound swabs. METHODS: The susceptibility to the three agents of S. aureus isolated from general patients in the south of The Netherlands with a skin or soft tissue infection was determined between January 2007 and December 2008. Fusidic acid-resistant isolates were tested for the presence of fusidic acid-resistant genes and compared with the epidemic European fusidic acid-resistant impetigo clone (EEFIC). RESULTS: Fusidic acid resistance was found in 23% of the nasal and 35% of the wound isolates, the majority (~90%) being fusB positive. Most of the isolates belonged to spa type t171 and were isolated from younger patients. One isolate was retapamulin resistant (MIC 8 mg/L) and two were mupirocin resistant. CONCLUSIONS: The EEFIC clone was relatively highly prevalent among the isolated S. aureus. The usefulness of fusidic acid as first-line agent for the treatment of impetigo is questionable. As mupirocin is used in The Netherlands for eradication of methicillin-resistant S. aureus, it is not an alternative; retapamulin might be useful, but further in vivo studies are warranted.

A 12 year (1998-2009) antibiotic resistance surveillance of Klebsiella pneumoniae collected from intensive care and urology patients in 14 Dutch hospitals.

OBJECTIVES: We evaluated the changes in antibiotic resistance from 1998 to 2009 of Klebsiella pneumoniae isolated from the intensive care units (ICUs) and urology services of 14 Dutch hospitals and the consequences for empirical therapy. METHODS: Quantitative antibiotic susceptibility testing of K. pneumoniae was performed in a central laboratory using a microbroth dilution method. Breakpoints were as defined by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). The prevalence of extended-spectrum ß-lactamase (ESBL)- and carbapenemase-producing isolates was determined. RESULTS: A significant increase in resistance among ICU isolates was observed for ceftazidime (4.2%-10.8%), ciprofloxacin (5.8%-18.5%) and trimethoprim/sulfamethoxazole (11.9%-23.1%), and for cefuroxime (2.8%-7.9%) and trimethoprim/sulfamethoxazole (13.5%-27.8%) among urology isolates. Among ICU isolates the prevalence of ESBLs increased significantly from 2% to 8%. Carbapenemase production was not demonstrated. Among ICU isolates the prevalence of multidrug resistance increased and has been ≥12% since 2004. Among urology isolates multidrug resistance was highest in 2009 at 7.4%. Overall, resistance was significantly higher among ICU isolates. CONCLUSIONS: We observed an increase in resistance among ICU and urology isolates and an increased prevalence of ESBLs among ICU isolates. Carbapenemase production was not demonstrated. A regular update of empirical treatment protocols based on actual surveillance data is justified.

Acceleration of the direct identification of Staphylococcus aureus versus coagulase-negative staphylococci from blood culture material: a comparison of six bacterial DNA extraction methods.

To accelerate differentiation between Staphylococcus aureus and coagulase-negative staphylococci (CNS), this study aimed to compare six different DNA extraction methods from two commonly used blood culture materials, i.e. BACTEC and BacT/ALERT. Furthermore, we analysed the effect of reduced blood culture incubation for the detection of staphylococci directly from blood culture material. A real-time polymerase chain reaction (PCR) duplex assay was used to compare the six different DNA isolation protocols on two different blood culture systems. Negative blood culture material was spiked with methicillin-resistant S. aureus (MRSA). Bacterial DNA was isolated with automated extractor easyMAG (three protocols), automated extractor MagNA Pure LC (LC Microbiology Kit M(Grade)), a manual kit MolYsis Plus and a combination of MolYsis Plus and the easyMAG. The most optimal isolation method was used to evaluate reduced bacterial incubation times. Bacterial DNA isolation with the MolYsis Plus kit in combination with the specific B protocol on the easyMAG resulted in the most sensitive detection of S. aureus, with a detection limit of 10 CFU/ml, in BacT/ALERT material, whereas using BACTEC resulted in a detection limit of 100 CFU/ml. An initial S. aureus or CNS load of 1 CFU/ml blood can be detected after 5 h of incubation in BacT/ALERT 3D by combining the sensitive isolation method and the tuf LightCycler assay.

Chlamydia pneumoniae infection enhances microglial activation in atherosclerotic mice.

The presence of Chlamydia pneumoniae in murine brain tissue was studied in atherosclerotic and non-atherosclerotic mice, after peritoneal injection. Furthermore, we investigated whether increased permeability of the blood-brain barrier was implicated in cerebral C. pneumoniae infection and whether intra-cerebral C. pneumoniae infection leads to microglial activation. Using a polymerase chain reaction, C. pneumoniae DNA was found in the brain tissue of 33% of the mice, 3, 7 and 21 days after infection. Atherosclerosis and age does not influence the extend of the cerebral infection. Semiquantitative analyses showed that intra-cerebral C. pneumoniae infection was not accompanied by an altered function of the blood-brain barrier. Microglial activation was assessed with immunohistochemistry, quantified in the hippocampus of each infected mouse and compared with mock infected. Enhanced microglial activation was found in the atherosclerotic mice. Since microglial activation is a key factor in a number of neuroinflammatory diseases, C. pneumoniae infection might play a role in these diseases.

TLR9 KO mice, haplotypes and CPG indices in Chlamydia trachomatis infection.

Previous studies have investigated the role of Toll-like receptor (TLR)2 and TLR4 in susceptibility to and severity of Chlamydia trachomatis infections. In this study we employ a unique integrated approach to study the role of the intracellular CpG DNA receptor: we use a murine knockout (KO) model to assess TLR9 relevance, study human TLR9 genotypes and haplotypes in sexually transmitted disease (STD) patients and subfertile women with or without tubal pathology and use in silico TLR9 CpG index calculations to assess potential immunostimulatory properties of the Chlamydia bacterium. Although no significant differences in the course of initial infections were observed between KO mice and wild-type mice the TLR9 KO mice showed a significant level of protection upon reinfection (P = 0.02). We did not observe significant differences in genotype frequencies between C. trachomatis-positive and C. trachomatisnegative women (STD patients). However, haplotype analyses revealed a trend between C. trachomatis-positive and C. trachomatis-negative women in the carriage of haplotype IV (P = 0.061; OR: 2.6; 95% CI: 1.0-6.8). In women with subfertility, odds ratios between 2 and 3 were found for tubal pathology risk, but they did not reach significance due to cohort size limitations. Finally, CpG sequence analysis showed mildly immunostimulatory properties for the genomic sequences of Chlamydia serovars B and D. Based on the murine model, human immunogenetic studies and in silico CpG index analyses, TLR9 seems to play a modest role in C. trachomatis infections. Extension of the human cohorts is necessary to significantly prove the effect in humans.

TLR4 in Chlamydia trachomatis infections: knockout mice, STD patients and women with tubal factor subfertility.

Chlamydia trachomatis is the most prevalent sexually transmitted bacterium in the world with almost 100 million new cases each year, some of which will develop tubal pathology. Clear differences in its clinical course of infections have been observed, and recently it has been shown that 40% is based on host genetic factors. We used an integrated approach based on infection of Toll-like receptor 4 (TLR4) knockout mice and immunogenetic analysis of female sexually transmitted disease (STD) patients (susceptibility) and women with C. trachomatis-associated tubal factor subfertility (severity). The results in TLR4 knockout mice suggest that the protection against reinfection is more solid in normal as compared to the TLR4-deficient mice. In humans the functional TLR4 single nucleotide polymorphism studied was not involved in the susceptibility to infection. However, C. trachomatis immunoglobulin (Ig) G-positive subfertile women with tubal pathology were more than twice as likely to be carriers of the mutant TLR4 +896 G allele as compared to those without tubal pathology; however this observation did not reach statistical significance. In conclusion, both the murine model and the human immunogenetics studies show a slight effect upon TLR4 deficiency in the severity of infection but not in the susceptibility to infection.

The inflammatory aspects of Chlamydia pneumoniae-induced brain infection.

The importance of inflammation in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease, is increasingly being recognized. Although amyloid-beta is considered to be one of the main initiators of these inflammatory processes, some reports suggest that brain infections may also contribute or even initiate the neuroinflammation. One of the best studied pathogens that might be involved in this phenomenon is the herpes simplex virus, but more recently the obligate intracellular respiratory Gram-negative bacterium, Chlamydia pneumoniae, has also been associated with Alzheimer's disease. The present article discusses recent data on the role of C. pneumoniae infection in neuroinflammation and its potential contribution to the pathogenesis of Alzheimer's disease.

Exploring the role of Chlamydia pneumoniae in cardiovascular disease: a narrative review.

An overwhelming number of studies have suggested that Chlamydia pneumoniae infections play a role in the development of atherosclerosis. Several, but not all, seroepidemiological studies have shown that C. pneumoniae antibodies may be related to the development of atherosclerotic disease. Additionally, C. pneumoniae seems to be present in atherosclerotic but not in healthy vascular tissue. Experimental studies have suggested a number of molecular mechanisms by which vascular C. pneumoniae infection might stimulate atherosclerosis development. Alternatively, nonvascular C. pneumoniae infection may cause clinically relevant atherosclerosis-related cardiovascular events through the systemic effects of chronic infection. Genetic variation may account for individual differences in susceptibility to the proatherogenic effects of C. pneumoniae infection. Despite the suggested role of infection in atherosclerosis, antibiotics seem to have no place in the secondary prevention of atherosclerosis-related cardiovascular events. The present narrative review evaluates the role of C. pneumoniae infections in the development of cardiovascular disease.

Surgical site infections: how high are the costs?

There is an increased interest in prevention of nosocomial infections and in the potential savings in healthcare costs. The aim of this review of recent studies on surgical site infections (SSIs) was to compare methods of cost research and magnitudes of costs due to SSI. The studies reviewed differ greatly with regard to study design and methods for cost calculation. However, healthcare costs for a patient with SSI are, on average, approximately twice the amount of costs for a patient without an SSI.

Evaluation of MeningoFinder, a novel multiplex ligation-dependent probe amplification assay for simultaneous detection of six virus species causing central nervous system infections.

A multiplex ligation-dependent probe amplification assay for simultaneous detection of six virus species was developed and tested on clinical cerebrospinal fluid (CSF) samples. The assay, termed MeningoFinder, showed an accordance of 97%, concordance of 96%, interlaboratory sensitivity of 90%, and interlaboratory specificity of 94% compared to PCRs.

Occupational risk of human Cytomegalovirus and Parvovirus B19 infection in female day care personnel in the Netherlands; a study based on seroprevalence.

Cytomegalovirus (CMV) and Parvovirus B19 infections acquired during pregnancy may result in developmental disabilities of the foetus. This study evaluates the occupational risk of these infections in female day care personnel. IgG seroprevalence was determined in 310 Dutch day care workers and 158 nursing school students. CMV seroprevalence was age-related, starting at 21% in those <20 years and reaching 65% in those >35 years. Between the ages of 20 and 24 years the CMV prevalence was higher in day care personnel than in controls, 50% versus 31% (p = 0.03). In the first 2 years of employment the risk of attracting CMV was significantly increased (OR(adj) = 3.80; p < 0.001) and the occupational risk was also increased (OR(adj) 2.19; p < 0.001). Parvovirus seropositivity (71-77%) was not related to age or working at a day care centre. In conclusion, an occupational risk was observed for CMV, but not for Parvovirus infection in female day care personnel.

Limited role for C. pneumoniae, CMV and HSV-1 in cerebral large and small vessel atherosclerosis.

AIMS: To explore whether Chlamydia pneumoniae, Cytomegalovirus and Herpes Simplex Virus type 1 could be detected in large and small cerebral arteries, as well as in an area of brain parenchyma where white matter lesions (leukoaraiosis) can be found, in patients with clinically unmanifested cerebrovascular atherosclerosis. Methods and results( Arterial specimens from the basilar artery and middle cerebral artery, and brain samples from the basal ganglia and periventricular white matter were obtained. Neuropathological changes were assessed in Haematoxylin-Eosin stained sections. Polymerase chain reaction (PCR) was performed on paraffin embedded sections. Subsequently, we performed immunohistochemical staining on samples, which were found positive in PCR. We failed to detect C. pneumoniae, CMV, or HSV-1, in any of the cerebral large vessels. In the brain tissue, we found only one case positive for CMV, and one for C. pneumoniae. Conclusions (our findings suggest a limited role for C. pneumoniae, CMV and HSV-1 in cerebral large and small vessel atherosclerosis.

Chemokines and chemokine receptors encoded by cytomegaloviruses.

CMVs carry several genes that are homologous to genes of the host organism. These include genes homologous to those encoding chemokines (CKs) and G protein-coupled receptors (GPCRs). It is generally assumed that these CMV genes were hijacked from the host genome during the long co-evolution of virus and host. In light of the important function of the CK and GPCR families in the normal physiology of the host, it has previously been hypothesized that the CMV homologs of these proteins, CMV vCKs and vGPCRs, may also have a significant impact on this physiology, such that lifelong maintenance and/or replication of the virus within the infected host is guaranteed. In addition, several of these homologs were reported to have a major impact in the pathogenesis of infection. In this review, the current state of knowledge on the CMV vCKs and vGPCRs will be discussed.