Anorectal Neisseria gonorrhoeae infections in women with and without reported anal sex and sex workers in sexual health centres in the Netherlands: a retrospective cohort study.

BACKGROUND: Control of Neisseria gonorrhoeae infection (gonorrhoea) depends on effective testing strategies. Anorectal testing in women is often done on indication of anal sex; however, anorectal infections are seen with and without anal exposure, possibly caused by autoinoculation. This study aims to enhance understanding of anorectal infections in women, by identifying risk factors for anorectal diagnosis. METHODS: In this retrospective cohort study we used national surveillance data from Dutch sexual health centres from Jan 1, 2016, to Dec 31, 2021. We included cisgender women having sex with men who were tested urogenitally and anorectally for gonorrhoea. Due to different testing policies, we identified three groups: women who had not reported recent anal sex (in the past 6 months), women who had reported recent anal sex, and sex workers. Extracted data for analyses included demographics, sexual behaviour, and diagnosis of a sexually transmitted infection (STI). Per group, multivariable models using Firth's penalised maximum likelihood logistic regression were constructed, identifying determinants of anorectal gonorrhoea among all women and among gonorrhoea-positive women only. Variables included in model construction were age, education level, migration background, number of partners, condom use, partner notification, STI symptoms, having a partner who has sex with men (MSM) or a migrant partner, previous STI test, anal sex, and chlamydia and gonorrhoea diagnoses per anatomical location. FINDINGS: In total, 117 693 women were included: 43 757 women without reported recent anal sex, 51 728 women with reported recent anal sex, and 22 208 sex workers. In all three groups, around 2% of women were gonorrhoea positive, and 70% or more of women had an anorectal infection. The strongest determinant of anorectal gonorrhoea was a concurrent urogenital gonorrhoea diagnosis (adjusted odds ratios [aOR] 782 [95% CI 605-1018]) among women without reported recent anal sex (612 [490-768] among women with reported recent anal sex, and 464 [335-652] among sex workers). Among gonorrhoea-positive women, determinants of anorectal gonorrhoea were urogenital and anorectal chlamydia co-infection (aOR 2·03 [95% CI 1·38-3·02], for women without reported anal sex) and migration background (1·44 [1·02-2·06], for women with reported anal sex). Determinants among sex workers were condomless sex (2·43 [1·55-3·82]), anal sex (1·71 [1·10-2·66]), MSM or migrant partner (1·78 [1·13-2·79]), and urogenital and anorectal chlamydia co-infection (2·28 [1·11-5·14]). INTERPRETATION: These findings support the possibility of an autoinoculation process from the urogenital to the anorectal location due to the very strong correlation between urogenital and anorectal gonorrhoea, and due to the similarity of results across all three groups. Current testing strategies could miss anorectal infections, which should be considered when developing gonorrhoea prevention and control guidelines. FUNDING: None.

Direct assessment of possible mutations in the 23S rRNA gene encoding macrolide resistance in Chlamydia trachomatis.

Reports of potential treatment failure have raised particular concerns regarding the efficacy of the single dose azithromycin regimen in the treatment of urogenital and anorectal Chlamydia trachomatis (CT) infections. Several factors have been suggested, including heterotypic resistance. Antimicrobial susceptibility testing in CT requires cell culture with serial dilutions of antibiotics, which is laborious and for which there is no standardized testing methodology. One method to partly overcome these difficulties would be to use a genotypic resistance assay, however most current available assays do still require prior CT culture. In order to facilitate the assessment of genotypic resistance directly from clinical samples, without the need for prior culture, the aim of this study was to develop a CT specific PCR assay for the assessment of resistance associated mutations (RAMs) in the 23S rRNA gene, and to evaluate a sample of clinical cases in which CT PCR's remained positive during follow-up despite azithromycin treatment. Neither the in silico analysis nor the analytical specificity testing demonstrated clinically relevant cross-reactivity with other bacterial species. These results in conjunction with the analytical sensitivity demonstrating consistent CT 23S rRNA gene detection in the range of 10e3 IFU/mL, exemplify the assay's apt performance. Although no known macrolide RAMs were detected in the clinical cases, the described assay allows future culture independent macrolide RAM surveillance in CT, and increases accessibility for other laboratories to engage in screening.

Chlamydia trachomatis intra-bacterial and total plasmid copy number in clinical urogenital samples.

Chlamydia trachomatis (CT) increases its plasmid numbers when stressed, as occurs in clinical trachoma samples. Most CT tests target the plasmid to increase the test sensitivity, but some only target the chromosome. We investigated clinical urogenital samples for total plasmid copy numbers to assess its diagnostic value and intra-bacterial plasmid copy numbers to assess its natural variation. Both plasmid and chromosome copies were quantified using qPCR, and the plasmid:chromosome ratio (PCr) calculated in two cohorts: (1) 383 urogenital samples for the total PCR (tPCr), and (2) 42 vaginal swabs, with one half treated with propium-monoazide (PMA) to prevent the quantification of extracellular DNA and the other half untreated to allow for both tPCr and intra-bacterial PCr (iPCr) quantification. Mann-Whitney U tests compared PCr between samples, in relation to age and gender. Cohort 1: tPCr varied greatly (1-677, median 16). Median tPCr was significantly higher in urines than vaginal swabs (32 vs. 11, p < 0.001). Cohort 2: iPCr was more stable than tPCr (range 0.1-3 vs. 1-11). To conclude, tPCr in urogenital samples was much more variable than previously described. Transport time and temperature influences DNA degradation, impacting chromosomal DNA more than plasmids and urine more than vaginal samples. Data supports a plasmid target in CT screening assays to increase clinical sensitivity.

Despite Excellent Test Characteristics of the cobas 4800 CT/NG Assay, Detection of Oropharyngeal Chlamydia trachomatis and Neisseria gonorrhoeae Remains Challenging.

Oropharyngeal Chlamydia trachomatis (CT) infections and, especially, Neisseria gonorrhoeae (NG) infections are common, but few commercial nucleic acid amplification tests (NAATs) specify extragenital samples for intended use. The test characteristics of the cobas 4800 CT/NG assay were evaluated for oropharyngeal swabs. The technical validation included analysis of the specificity, sensitivity, dynamic range, linearity, efficiency, and precision. The probability of detection curve combined with historical data enabled the estimation of potentially missed diagnoses. A clinical evaluation was performed on a subset of 2,798 clinical samples available from routine diagnostics. Results of the cobas 4800 were compared with those from in-house C. trachomatis/N. gonorrhoeae PCR assays. Discrepant samples were tested with resolver assays, and these results were considered decisive. No cross-reactivity was seen in the analytical specificity analysis. High linearity (R2 ≥ 0.983), efficiency (89% to 99%), and precision (cycle threshold [CT ] value of 0.1 to 0.9) were seen for both C. trachomatis and N. gonorrhoeae The limit of detection in oropharyngeal samples was 3.2 × 102 inclusion-forming units (IFU)/ml for C. trachomatis and 6.7 × 102 CFU/ml for N. gonorrhoeae Estimates on potentially missed diagnoses were up to 7.2% for C. trachomatis and up to 24.7% for N. gonorrhoeae Clinical sensitivity and specificity were evaluated with 25 C. trachomatis-positive, 86 N. gonorrhoeae-positive, and 264 negative samples, resulting in 100% and 99.6% for C. trachomatis and 100% and 96.7% for N. gonorrhoeae, respectively. The findings in this study demonstrate the utility of the cobas 4800 CT/NG assay for oropharyngeal samples. Despite its being a highly accurate test, the range of reported CT values, especially for N. gonorrhoeae, suggests relatively low oropharyngeal loads. Hence, consistent detection over the full range of oropharyngeal loads could be impaired.

Pilot implementation of a home-care programme with chlamydia, gonorrhoea, hepatitis B, and syphilis self-sampling in HIV-positive men who have sex with men.

BACKGROUND: Not all men who have sex with men (MSM) at risk for sexually transmitted infections (STIs) and human immunodeficiency virus (HIV) infection currently receive sexual healthcare. To increase the coverage of high-quality HIV/STI care for MSM, we developed a home-care programme, as extended STI clinic care. This programme included home sampling for testing, combined with treatment and sexual health counselling. Here, we pilot implemented the programme in a hospital setting (HIV-positive MSM) to determine the factors for the successful implementation of STI home sampling strategies. METHODS: Healthcare providers from the HIV hospital treatment centre (Maastricht) were invited to offer free STI sampling kits (syphilis, hepatitis B, [extra]genital chlamydia and gonorrhoea laboratory testing) to their HIV-positive MSM patients (March to May 2018). To evaluate implementation of the program, quantitative and qualitative data were collected to assess adoption (HIV care providers offered sampling kits to MSM), participation (MSM accepted the sampling kits) and sampling-kit return, STI diagnoses, and implementation experiences. RESULTS: Adoption was 85.3% (110/129), participation was 58.2% (64/110), and sampling-kit return was 43.8% (28/64). Of the tested MSM, 64.3% (18/28) did not recently (< 3 months) undergo a STI test; during the programme, 17.9% (5/28) were diagnosed with an STI. Of tested MSM, 64.3% (18/28) was vaccinated against hepatitis B. MSM reported that the sampling kits were easily and conveniently used. Care providers (hospital and STI clinic) considered the programme acceptable and feasible, with some logistical challenges. All (100%) self-taken chlamydia and gonorrhoea samples were adequate for testing, and 82.1% (23/28) of MSM provided sufficient self-taken blood samples for syphilis screening. However, full syphilis diagnostic work-up required for MSM with a history of syphilis (18/28) was not possible in 44.4% (8/18) of MSM because of insufficient blood sampled. CONCLUSION: The home sampling programme increased STI test uptake and was acceptable and feasible for MSM and their care providers. Return of sampling kits should be further improved. The home-care programme is a promising extension of regular STI care to deliver comprehensive STI care to the home setting for MSM. Yet, in an HIV-positive population, syphilis diagnosis may be challenging when using self-taken blood samples.

Complex narratives of health, stigma and control: Antimicrobial resistance screening among non-hospitalized refugees.

Antimicrobial resistance (AMR) is often presented as a major public health problem globally. Screening for AMR usually takes place in clinical settings. Recent developments in microbiology stimulated a series of studies focusing on AMR in communities, and particularly in travelers (any mobile individual), which was argued to be important for identifying potential public health risks. Against this background, microbiologists have become interested in non-hospitalized refugees as one of the traveler groups. However, this attention to refugees has provoked some professional debates on potential stigmatization of refugees as dangerous "others". To contribute to these debates, and to explore the idea of AMR screening of non-hospitalized refugees from different perspectives, we conducted a qualitative study among four groups of stakeholders who were chosen because of their associations with potential microbiological screening: microbiologists, public health physicians, public health nurses, and refugees. The study took place in a Dutch city from June to August 2016 and had 17 participants: five microbiologists, two public health nurses, four public health physicians, and six refugees. While microbiologists and public health physicians demonstrated a de-contextualized biomedical narrative in arguing that AMR screening among non-hospitalized refugees could be important for scientific research as well as for AMR prevention in communities, public health nurses displayed a more contextualized narrative bringing the benefits for individuals at the center and indicating that screening exclusively among refugees may provoke fear and stigmatization. Refugees were rather positive about AMR screening but stressed that it should particularly contribute to their individual health. We conclude that to design AMR prevention strategies, it is important to consider the complex meanings of AMR screening, and to design these strategies as a process of co-production by diverse stakeholders, including the target populations.

Natural Course of Chlamydia trachomatis Bacterial Load in the Time Interval between Screening and Treatment in Anogenital Samples.

INTRODUCTION: Although Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection worldwide, little is known about the natural course of the bacterial load during infection. We investigated the natural course of the bacterial load in the interval between screening and returning for treatment in genital and anorectal CT-infections. MATERIALS & METHODS: CT-positive patients, visiting our STI-clinic in the Netherlands from June 2011-January 2014, provided a second urogenital and/or anorectal sample when returning for treatment (diagnostic sample = T1; treatment sample = T2). Patient-record provided data about the days between samples and the date of last unsafe sex. Included patients were ≥18 years old, HIV-negative and did not report antibiotic use in the study-interval. CT load was quantified using qPCR. CT load was log-transformed, and a CT load difference (Δ-CT load) of >1 log was deemed clinically relevant. Chi-square test compared load category distributions over time (decrease/equal/increase), between sample types. RESULTS: 274 patients provided 296 paired samples. Majority of samples had a stable CT load in the interval T1-T2 (66.3%, 73.1% and 48.6% for vaginal swabs, urine and anorectal swabs resp. p = 0.07). Load decreased in 17-41% of patients, while ±10% of patients showed an increase in CT load. No association between Δ-CT load and the interval T1-T2 was observed. Large variations can be seen in CT load at T1 and over time. DISCUSSION: The majority (±90%) of patients have a stable or decreasing CT load in the time interval between screening and returning for treatment. The number of days between sampling was not associated with change in CT load. In the first month after the last unsafe sex, only stable CT loads were seen. Our data seems to indicate that when most patients visit an STI-clinic, recommended 2 weeks after infection, the infection has already been established or is in its downward phase.

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.

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.

An evaluation of three processing methods and the effect of reduced culture times for faster direct identification of pathogens from BacT/ALERT blood cultures by MALDI-TOF MS.

Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) is a fast and reliable method for the identification of bacteria from agar media. Direct identification from positive blood cultures should decrease the time to obtaining the result. In this study, three different processing methods for the rapid direct identification of bacteria from positive blood culture bottles were compared. In total, 101 positive aerobe BacT/ALERT bottles were included in this study. Aliquots from all bottles were used for three bacterial processing methods, i.e. the commercially available Bruker's MALDI Sepsityper kit, the commercially available Molzym's MolYsis Basic5 kit and a centrifugation/washing method. In addition, the best method was used to evaluate the possibility of MALDI application after a reduced incubation time of 7 h of Staphylococcus aureus- and Escherichia coli-spiked (1,000, 100 and 10 colony-forming units [CFU]) aerobe BacT/ALERT blood cultures. Sixty-six (65%), 51 (50.5%) and 79 (78%) bottles were identified correctly at the species level when the centrifugation/washing method, MolYsis Basic 5 and Sepsityper were used, respectively. Incorrect identification was obtained in 35 (35%), 50 (49.5%) and 22 (22%) bottles, respectively. Gram-positive cocci were correctly identified in 33/52 (64%) of the cases. However, Gram-negative rods showed a correct identification in 45/47 (96%) of all bottles when the Sepsityper kit was used. Seven hours of pre-incubation of S. aureus- and E. coli-spiked aerobe BacT/ALERT blood cultures never resulted in reliable identification with MALDI-TOF MS. Sepsityper is superior for the direct identification of microorganisms from aerobe BacT/ALERT bottles. Gram-negative pathogens show better results compared to Gram-positive bacteria. Reduced incubation followed by MALDI-TOF MS did not result in faster reliable identification.

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.

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.

Rapid screening of methicillin-resistant Staphylococcus aureus using PCR and chromogenic agar: a prospective study to evaluate costs and effects.

Pre-emptive isolation of suspected methicillin-resistant Staphylococcus aureus (MRSA) carriers is considered essential for controlling the spread of MRSA, but noncolonized patients will be isolated unnecessarily as a result of a delay in diagnosis of 3-5 days with conventional cultures. We determined costs per isolation day avoided, and incremental costs of rapid MRSA screening tests when added to conventional screening, but with decisions on isolation measures based on PCR results. A prospective multicentre study evaluating BD GeneOhm MRSA PCR (`IDI') (BD Diagnostics, San Diego, CA, USA), Xpert MRSA (`GeneXpert') (Cepheid, Sunnyvale, CA, USA) and chromogenic agar (MRSA-ID) (bioMérieux, Marcy-l'Etoile, France) was performed in 14 Dutch hospitals. Among 1764 patients at risk, MRSA prevalence was 3.3% (n=59). Duration of isolation was 19.7 and 16.1 h with IDI and GeneXpert, respectively, and would have been 30.0 and 76.2 h when based on chromogenic agar and conventional cultures, respectively. Negative predictive values (at a patient level) were 99.5%, 99.1% and 99.5% for IDI, GeneXpert and chromogenic agar, respectively. Numbers of isolation days were reduced by 60% and 47% with PCR-based and chromogenic agar-based screening, respectively. The cost per test was €56.22 for IDI, €69.62 for GeneXpert and €2.08 for chromogenic agar, and additional costs per extra isolation day were €26.34. Costs per isolation day avoided were €95.77 (IDI) and €125.43 (GeneXpert). PCR-based decision-making added €153.64 (IDI) and €193.84 (GeneXpert) per patient to overall costs and chromogenic testing would have saved €30.79 per patient. Rapid diagnostic testing safely reduces the number of unnecessary isolation days, but only chromogenic screening, and not PCR-based screening, can be considered as cost saving.

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.

Role of efflux pumps in adaptation and resistance of Listeria monocytogenes to benzalkonium chloride.

In this study, potential mechanisms underlying resistance and adaptation to benzalkonium chloride (BC) in Listeria monocytogenes were investigated. Two groups of strains were studied. The first group consisted of strains naturally sensitive to BC which could be adapted to BC. The second group consisted of naturally resistant strains. For all adapted isolates, there was a correlation between the resistance to BC and ethidium bromide, but this was not the case for the naturally resistant isolates. To investigate the role of efflux pumps in adaptation or resistance, reserpine, an efflux pump inhibitor, was added to the strains. Addition of reserpine to the sensitive and adapted strains resulted in a decrease in the MIC for BC, whereas no such decrease was observed for the resistant strains, indicating that efflux pumps played no role in the innate resistance of certain strains of L. monocytogenes to this compound. Two efflux pumps (MdrL and Lde) have been described in L. monocytogenes. Studies showed low and intermediate levels of expression of the genes encoding the efflux pumps for two selected resistant strains, H7764 and H7962, respectively. Adaptation to BC of sensitive isolates of L. monocytogenes resulted in significant increases in expression of mdrl (P < 0.05), but no such increase was observed for lde for two adapted strains of L. monocytogenes, LJH 381 (P = 0.91) and C719 (P = 0.11). This indicates that the efflux pump Mdrl is at least partly responsible for the adaptation to BC.