[Mycoplasma pneumoniaeoutbreak in the Netherlands 2023-2024]. / Mycoplasma pneumoniae-uitbraak in Nederland 2023-2024.

Currently, there is a nationwide outbreak of Mycoplasma pneumoniae infections. M. pneumoniae is a bacterium that can cause atypical pneumonia, especially in children and young adults, and does not respond to the standard antibiotics prescribed for pneumonia. In addition, the bacterium regularly causes extra-pulmonary symptoms. In our hospitals, we have admitted 100 patients (including 20 children) with M. pneumoniae since the fall of 2023, many of which were young and had severe clinical symptoms. It is important to recognize the clinical picture to start effective antibiotic treatment. In this clinical lesson, we will provide two examples of recently admitted patients and discuss the characteristics of all inpatients who have presented to our hospitals during this epidemic. Finally, we pay attention to antibiotic policy and antibiotic resistance.

Using the Sysmex UF-4000 urine flow cytometer for rapid diagnosis of urinary tract infection in the clinical microbiological laboratory.

BACKGROUND: Urinary tract infections are responsible for a significant worldwide disease burden. Performing urine culture is time consuming and labor intensive. Urine flow cytometry might provide a quick and reliable method to screen for urinary tract infection. METHODS: We analyzed routinely collected urine samples received between 2020 and 2022 from both inpatients and outpatients. The UF-4000 urine flow cytometer was implemented with an optimal threshold for positivity of ≥100 bacteria/µL. We thereafter validated the prognostic value to detect the presence of urinary tract infection (UTI) based on bacterial (BACT), leukocyte (WBC), and yeast-like cell (YLC) counts combined with the bacterial morphology (UF gram-flag). RESULTS: In the first phase, in 2019, the UF-4000 was implemented using 970 urine samples. In the second phase, between 2020 and 2022, the validation was performed in 42,958 midstream urine samples. The UF-4000 screen resulted in a 37% (n = 15,895) decrease in performed urine cultures. Uropathogens were identified in 18,673 (69%) positively flagged urine samples. BACT > 10.000/µL combined with a gram-negative flag had a >90% positive predictive value for the presence of gram-negative uropathogens. The absence of gram-positive flag or YLC had high negative predictive values (99% and >99%, respectively) and are, therefore, best used to rule out the presence of gram-positive bacteria or yeast. WBC counts did not add to the prediction of uropathogens. CONCLUSION: Implementation of the UF-4000 in routine practice decreased the number of cultured urine samples by 37%. Bacterial cell counts were highly predictive for the presence of UTI, especially when combined with the presence of a gram-negative flag.

Cost Effectiveness of Rectal Culture-based Antibiotic Prophylaxis in Transrectal Prostate Biopsy: The Results from a Randomized, Nonblinded, Multicenter Trial.

Background: Culture-based antibiotic prophylaxis is a plausible strategy to reduce infections after transrectal prostate biopsy (PB) related to fluoroquinolone-resistant pathogens. Objective: To assess the cost effectiveness of rectal culture-based prophylaxis compared with empirical ciprofloxacin prophylaxis. Design setting and participants: The study was performed alongside a trial in 11 Dutch hospitals investigating the effectiveness of culture-based prophylaxis in transrectal PB between April 2018 and July 2021 (trial registration number: NCT03228108). Intervention: Patients were 1:1 randomized for empirical ciprofloxacin prophylaxis (oral) or culture-based prophylaxis. Costs for both prophylactic strategies were determined for two scenarios: (1) all infectious complications within 7 d after biopsy and (2) culture-proven Gram-negative infections within 30 d after biopsy. Outcome measurements and statistical analysis: Differences in costs and effects (quality-adjusted life-years [QALYs]) were analyzed from a healthcare and societal perspective (including productivity losses, and travel and parking costs) using a bootstrap procedure presenting uncertainty surrounding the incremental cost-effectiveness ratio in a cost-effectiveness plane and acceptability curve. Results and limitations: For the 7-d follow-up period, culture-based prophylaxis (n = 636) was €51.57 (95% confidence interval [CI] 6.52-96.63) more expensive from a healthcare perspective and €16.95 (95% CI -54.29 to 88.18) from a societal perspective than empirical ciprofloxacin prophylaxis (n = 652). Ciprofloxacin-resistant bacteria were detected in 15.4%. Extrapolating our data, from a healthcare perspective, 40% ciprofloxacin resistance would lead to equal cost for both strategies. Results were similar for the 30-d follow-up period. No significant differences in QALYs were observed. Conclusions: Our results should be interpreted in the context of local ciprofloxacin resistance rates. In our setting, from a healthcare perspective, culture-based prophylaxis was significantly more expensive than empirical ciprofloxacin prophylaxis. From a societal perspective, culture-based prophylaxis was somewhat more cost effective against the threshold value customary for the Netherlands (€80.000). Patient summary: Culture-based prophylaxis in transrectal prostate biopsy was not associated with reduced costs compared with empirical ciprofloxacin prophylaxis.

Rectal Culture-Based Versus Empirical Antibiotic Prophylaxis to Prevent Infectious Complications in Men Undergoing Transrectal Prostate Biopsy: A Randomized, Nonblinded Multicenter Trial.

BACKGROUND: An increase in infections after transrectal prostate biopsy (PB), related to an increasing number of patients with ciprofloxacin-resistant rectal flora, necessitates the exploration of alternatives for the traditionally used empirical prophylaxis of ciprofloxacin. We compared infectious complication rates after transrectal PB using empirical ciprofloxacin prophylaxis versus culture-based prophylaxis. METHODS: In this nonblinded, randomized trial, between 4 April 2018 and 30 July 2021, we enrolled 1538 patients from 11 Dutch hospitals undergoing transrectal PB. After rectal swab collection, patients were randomized 1:1 to receive empirical prophylaxis with oral ciprofloxacin (control group [CG]) or culture-based prophylaxis (intervention group [IG]). Primary outcome was any infectious complication within 7 days after biopsy. Secondary outcomes were infectious complications within 30 days, and bacteremia and bacteriuria within 7 and 30 days postbiopsy. For primary outcome analysis, the χ2 test stratified for hospitals was used. Trial registration number: NCT03228108. RESULTS: Data from 1288 patients (83.7%) were available for analysis (CG, 652; IG, 636). Infection rates within 7 days postbiopsy were 4.3% (n = 28) (CG) and 2.5% (n = 16) (IG) (P value = .08; reduction: -1.8%; 95% confidence interval, -.004 to .040). Ciprofloxacin-resistant bacteria were detected in 15.2% (n = 1288). In the CG, the presence of ciprofloxacin-resistant rectal flora resulted in a 6.2-fold higher risk of early postbiopsy infection. CONCLUSIONS: Our study supports the use of culture-based prophylaxis to reduce infectious complications after transrectal PB. Despite adequate prophylaxis, postbiopsy infections can still occur. Therefore, culture-based prophylaxis must be weighed against other strategies that could reduce postbiopsy infections. Clinical Trials Registration. NCT03228108.

First Case of Human Brucella canis Infection in the Netherlands.

A patient was diagnosed with Brucella canis following exposure to infected dogs in her breeding facility. Transboundary spread of B. canis through (illegal) import of infected dogs to non-endemic countries in Europe suggest that B. canis infection should be considered in European patients with occupational exposure to dogs.

An Integral Pharmacokinetic Analysis of Piperacillin and Tazobactam in Plasma and Urine in Critically Ill Patients.

BACKGROUND AND OBJECTIVES: Although dose optimization studies have been performed for piperacillin and tazobactam separately, a combined integral analysis is not yet reported. As piperacillin and tazobactam pharmacokinetics are likely to show correlation, a combined pharmacokinetic model should be preferred to account for this correlation when predicting the exposure. Therefore, the aim of this study was to describe the pharmacokinetics and evaluate different dosing regimens of piperacillin and tazobactam in critically ill patients using an integral population pharmacokinetic model in plasma and urine. METHODS: In this observational study, a total of 39 adult intensive care unit patients receiving piperacillin-tazobactam as part of routine clinical care were included. Piperacillin and tazobactam concentrations in plasma and urine were measured and analyzed using non-linear mixed-effects modeling. Monte Carlo simulations were performed to predict the concentrations for different dosing strategies and different categories of renal function. RESULTS: A combined two-compartment linear pharmacokinetic model for both piperacillin and tazobactam was developed, with an output compartment for the renally excreted fraction. The addition of 24-h urine creatinine clearance significantly improved the model fit. A dose of 12/1.5 g/24 h as a continuous infusion is sufficient to reach a tazobactam concentration above the target (2.89 mg/L) and a piperacillin concentration above the target of 100% f T>1×MIC (minimum inhibitory concentration [MIC] ≤ 16 mg/L). To reach a target of 100% f T>5×MIC with an MIC of 16 mg/L, piperacillin doses of up to 20 g/24 h are inadequate. Potential toxic piperacillin levels were reached in 19.6% and 47.8% of the population with a dose of 12 g/24 h and 20 g/24 h, respectively. CONCLUSIONS: A regular dose of 12/1.5 g/24 h is sufficient in > 90% of the critically ill population to treat infections caused by Escherichia coli and Klebsiella pneumoniae with MICs ≤ 8 mg/L. In case of infections caused by Pseudomonas aeruginosa with an MIC of 16 mg/L, there is a fine line between therapeutic and toxic exposure. Dosing guided by renal function and therapeutic drug monitoring could enhance target attainment in such cases. GOV IDENTIFIER: NCT03738683.

The Effect of Different Types of Prostate Biopsy Techniques on Post-Biopsy Infectious Complications.

PURPOSE: The aim of our study was to compare infectious complication rates between different prostate biopsy techniques with various number of biopsy cores. MATERIALS AND METHODS: In this retrospective study, all patients from 2 hospitals who underwent prostate biopsy between 2012 and 2019 were identified. Cohorts with different types of prostate biopsies were compiled within these hospitals. Primary outcome measure was any registered infectious complication within 7 days post-biopsy. Secondary outcomes were infectious complications within 30 days, hospitalization and bacteremia. To compare the risk of infection following different prostate biopsy techniques, data was fitted into a logistic regression model adjusting for potential confounders. RESULTS: In total, 4,233 prostate biopsies in 3,707 patients were included. After systematic transrectal ultrasound-guided prostate biopsy (TRUSPB; 12±1.4 biopsy cores), 4.0% (2,607) of all patients had infectious complications within 7 days post-biopsy. Transperineal magnetic resonance imaging (MRI)-ultrasound fusion guided prostate biopsy (16±3.7 biopsy cores) was associated with significantly lower infection rates than systematic TRUSPB (adjusted OR: 0.29 [0.09-0.73] 95% confidence interval [CI]). Transrectal targeted MRI-ultrasound fusion guided prostate biopsy (3.1±0.8 biopsy cores) and transrectal targeted in-bore MRI guided prostate biopsy (2.8±0.8 biopsy cores) also showed fewer infectious complications than systematic TRUSPB (adjusted OR: 0.41 [0.12-1.12] 95% CI and 0.68 [0.37-1.20] 95% CI, respectively). CONCLUSIONS: Transperineal prostate biopsy, or transrectal prostate biopsy with reduced number of biopsy cores, could lower the risk of infectious complications.

Acceptability of innovative culture-based antibiotic prophylaxis strategies: a multi-method study on experiences regarding transrectal prostate biopsy.

BACKGROUND: The acceptability of innovative medical strategies among healthcare providers and patients affects their uptake in daily clinical practice. OBJECTIVES: To explore experiences of healthcare providers and patients with culture-based antibiotic prophylaxis in transrectal prostate biopsy with three swab-screening scenarios: self-sampling at home, self-sampling in the hospital and sampling by a healthcare provider. METHODS: We performed focus group interviews with urologists and medical microbiologists from 11 hospitals and six connected clinical microbiological laboratories. We used Flottorp's comprehensive checklist for identifying determinants of practice to guide data collection and analysis. The experiences of 10 laboratory technicians from five laboratories and 452 patients from nine hospitals were assessed using a questionnaire. RESULTS: Overall, culture-based prophylaxis strategies were experienced as feasible in daily clinical practice. None of the three swab-screening scenarios performed better. For urologists (n = 5), implementation depended on the effectiveness of the strategy. In addition, it was important to them that the speed of existing oncology care pathways is preserved. Medical microbiologists (n = 5) and laboratory technicians (n = 8) expected the strategy to be fairly easy to implement. Patients (n = 430; response rate 95.1%) were generally satisfied with the screening scenario presented to them. To meet the various patients' needs and preferences, multiple scenarios within a hospital are probably needed. CONCLUSIONS: This multi-method study has increased our understanding of the acceptability of culture-based prophylaxis strategies in prostate biopsy, which can help healthcare providers to offer high-quality patient-centred care. The strategy seems relatively straightforward to implement as overall acceptance appears to be high.

High unbound flucloxacillin fraction in critically ill patients.

OBJECTIVES: To describe the unbound and total flucloxacillin pharmacokinetics in critically ill patients and to define optimal dosing strategies. PATIENTS AND METHODS: Observational multicentre study including a total of 33 adult ICU patients receiving flucloxacillin, given as intermittent or continuous infusion. Pharmacokinetic sampling was performed on two occasions on two different days. Total and unbound flucloxacillin concentrations were measured and analysed using non-linear mixed-effects modelling. Serum albumin was added as covariate on the maximum binding capacity and endogenous creatinine clearance (CLCR) as covariate for renal function. Monte Carlo simulations were performed to predict the unbound flucloxacillin concentrations for different dosing strategies and different categories of endogenous CLCR. RESULTS: The measured unbound concentrations ranged from 0.2 to 110 mg/L and the observed unbound fraction varied between 7.0% and 71.7%. An integral two-compartmental linear pharmacokinetic model based on total and unbound concentrations was developed. A dose of 12 g/24 h was sufficient for 99.9% of the population to achieve a concentration of >2.5 mg/L (100% fT>5×MIC, MIC = 0.5 mg/L). CONCLUSIONS: Critically ill patients show higher unbound flucloxacillin fractions and concentrations than previously thought. Consequently, the risk of subtherapeutic exposure is low.

Genome-wide analysis in Escherichia coli unravels a high level of genetic homoplasy associated with cefotaxime resistance.

Cefotaxime (CTX) is a third-generation cephalosporin (3GC) commonly used to treat infections caused by Escherichia coli. Two genetic mechanisms have been associated with 3GC resistance in E. coli. The first is the conjugative transfer of a plasmid harbouring antibiotic-resistance genes. The second is the introduction of mutations in the promoter region of the ampC ß-lactamase gene that cause chromosome-encoded ß-lactamase hyperproduction. A wide variety of promoter mutations related to AmpC hyperproduction have been described. However, their link to CTX resistance has not been reported. We recultured 172 cefoxitin-resistant E. coli isolates with known CTX minimum inhibitory concentrations and performed genome-wide analysis of homoplastic mutations associated with CTX resistance by comparing Illumina whole-genome sequencing data of all isolates to a PacBio sequenced reference chromosome. We mapped the mutations on the reference chromosome and determined their occurrence in the phylogeny, revealing extreme homoplasy at the -42 position of the ampC promoter. The 24 occurrences of a T at the -42 position rather than the wild-type C, resulted from 18 independent C>T mutations in five phylogroups. The -42 C>T mutation was only observed in E. coli lacking a plasmid-encoded ampC gene. The association of the -42 C>T mutation with CTX resistance was confirmed to be significant (false discovery rate <0.05). To conclude, genome-wide analysis of homoplasy in combination with CTX resistance identifies the -42 C>T mutation of the ampC promotor as significantly associated with CTX resistance and underlines the role of recurrent mutations in the spread of antibiotic resistance.

Selective Decontamination of the Digestive Tract to Prevent Postoperative Pneumonia and Anastomotic Leakage after Esophagectomy: A Retrospective Cohort Study.

Infectious complications occur frequently after esophagectomy. Selective decontamination of the digestive tract (SDD) has been shown to reduce postoperative infections and anastomotic leakage in gastrointestinal surgery, but robust evidence for esophageal surgery is lacking. The aim was to evaluate the association between SDD and pneumonia, surgical-site infections (SSIs), anastomotic leakage, and 1-year mortality after esophagectomy. A retrospective cohort study was conducted in patients undergoing Ivor Lewis esophagectomy in four Dutch hospitals between 2012 and 2018. Two hospitals used SDD perioperatively and two did not. SDD consisted of an oral paste and suspension (containing amphotericin B, colistin, and tobramycin). The primary outcomes were 30-day postoperative pneumonia and SSIs. Secondary outcomes were anastomotic leakage and 1-year mortality. Logistic regression analyses were performed to determine the association between SDD and the relevant outcomes (odds ratio (OR)). A total of 496 patients were included, of whom 179 received SDD perioperatively and the other 317 patients did not receive SDD. Patients who received SDD were less likely to develop postoperative pneumonia (20.1% vs. 36.9%, p < 0.001) and anastomotic leakage (10.6% vs. 19.9%, p = 0.008). Multivariate analysis showed that SDD is an independent protective factor for postoperative pneumonia (OR 0.40, 95% CI 0.23-0.67, p < 0.001) and anastomotic leakage (OR 0.46, 95% CI 0.26-0.84, p = 0.011). Use of perioperative SDD seems to be associated with a lower risk of pneumonia and anastomotic leakage after esophagectomy.

Recovery of aerobic gram-negative bacteria from the Copan Eswab transport system after long-term storage.

We evaluated the Copan Eswab transport system for the quantitative recovery of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa after 1, 2, 3, 5, and 7 days of storage at room and refrigerator temperatures, and 7 and 30 days of storage at -80 °C and -20 °C using mono- and polymicrobial samples. The study was based on Clinical and Laboratory Standards Institute (CLSI) M40-A2 standard procedures on the quality control of microbiological transport systems. Eswab met the CLSI standards at room and refrigerator temperatures for all (combinations of) bacterial strains tested. At room temperature, after 24 h, bacterial growth was observed. At -80 °C, bacterial viability was maintained in monomicrobial samples; however, in polymicrobial samples, P. aeruginosa recovery was compromised. Storage at -20 °C was unsuitable. We conclude that specimens collected using Eswab should be transported to the laboratory as soon as possible. If transport or processing is delayed, specimens should preferably be stored at refrigerator temperatures.

Epidemiology and Clinical Management of Fusarium keratitis in the Netherlands, 2005-2016.

Introduction: Recognizing fungal keratitis based on the clinical presentation is challenging. Topical therapy may be initiated with antibacterial agents and corticosteroids, thus delaying the fungal diagnosis. As a consequence, the fungal infection may progress ultimately leading to more severe infection and blindness. We noticed an increase of fungal keratitis cases in the Netherlands, especially caused by Fusarium species, which prompted us to conduct a retrospective cohort study, aiming to describe the epidemiology, clinical management, and outcome. Materials and Methods: As fungi are commonly sent to the Dutch mycology reference laboratory for identification and in vitro susceptibility testing, the fungal culture collection was searched for Fusarium isolates from corneal scrapings, corneal swabs, and from contact lens (CL) fluid, between 2005 and 2016. All Fusarium isolates had been identified up to species level through sequencing of the ITS1-5.8S-ITS2 region of the rDNA and TEF1 gene. Antifungal susceptibility testing was performed according to the EUCAST microbroth dilution reference method. Antifungal agents tested included amphotericin B, voriconazole, and natamycin. In addition, susceptibility to the antisepticum chlorhexidine was tested. Ophthalmologists were approached to provide demographic and clinical data of patients identified through a positive culture. Results: Between 2005 and 2016, 89 cases of Fusarium keratitis from 16 different hospitals were identified. The number of cases of Fusarium keratitis showed a significant increase over time (R2 = 0.9199), with one case in the first 5 years (2005-2009) and multiple cases from 2010 and onwards. The male to female ratio was 1:3 (p = 0.014). Voriconazole was the most frequently used antifungal agent, but treatment strategies differed greatly between cases including five patients that were treated with chlorhexidine 0.02% monotherapy. Keratitis management was not successful in 27 (30%) patients, with 20 (22%) patients requiring corneal transplantation and seven (8%) requiring enucleation or evisceration. The mean visual acuity (VA) was moderately impaired with a logMAR of 0.8 (95% CI 0.6-1, Snellen equivalent 0.16) at the time of Fusarium culture. Final average VA was within the range of normal vision [logMAR 0.2 (95% CI 0.1-0.3), Snellen equivalent 0.63]. CL wear was reported in 92.9% of patients with Fusarium keratitis. The time between start of symptoms and diagnosis of fungal keratitis was significantly longer in patients with poor outcome as opposed to those with (partially) restored vision; 22 vs. 15 days, respectively (mean, p = 0.024). Enucleation/evisceration occurred in patients with delayed fungal diagnosis of more than 14 days after initial presentation of symptoms. The most frequently isolated species was F. oxysporum (24.7%) followed by F. solani sensu stricto (18%) and F. petroliphilum (9%). The lowest MICs were obtained with amphotericin B followed by natamycin, voriconazole, and chlorhexidine. Conclusion: Although Fusarium keratitis remains a rare complication of CL wear, we found a significant increase of cases in the Netherlands. The course of infection may be severe and fungal diagnosis was often delayed. Antifungal treatment strategies varied widely and the treatment failure rate was high, requiring transplantation or even enucleation. Our study underscores the need for systematic surveillance of fungal keratitis and a consensus management protocol.

Higher Dosage of Ciprofloxacin Necessary in Critically Ill Patients: A New Dosing Algorithm Based on Renal Function and Pathogen Susceptibility.

The objective of the present study was to develop a dosing algorithm for ciprofloxacin based on both renal function and pathogen susceptibility in critically ill patients. In this observational prospective multicenter pharmacokinetic study, a total of 39 adult intensive care unit patients receiving ciprofloxacin were included. On two occasions a total of 531 samples of ciprofloxacin were collected. Renal function is a significant covariate on ciprofloxacin clearance. A dose of 400 mg every 12 hours was sufficient to reach the preestablished target of area under the curve (AUC) in relation to the minimum inhibitory concentration (MIC) (AUC/MIC) > 125 in patients with an estimated glomerular filtration rate (eGFR) < 130 mL/min and an infection caused by a pathogen with an MIC ≤ 0.125 mg/L. For patients with infections caused by pathogens with an MIC ≥ 0.5 mg/L and eGFR> 100 mL/min, doses up to 600 mg four times daily or more were estimated to be required. This study provides a new dosing algorithm for ciprofloxacin in critically ill patients. In order to achieve adequate target attainment, the dosing of ciprofloxacin should be based on renal function and the MIC of the causative pathogen. Higher doses than the standard licensed dose are necessary to obtain target attainment for less susceptible pathogens and patients with high renal clearance. In the setting of impaired renal function, a daily dose of 400 mg (which is currently recommended) will not result in adequate target attainment for less susceptible pathogens.

Prostate biopsy techniques and pre-biopsy prophylactic measures: variation in current practice patterns in the Netherlands.

BACKGROUND: The clinical landscape of prostate biopsy (PB) is evolving with changes in procedures and techniques. Moreover, antibiotic resistance is increasing and influences the efficacy of pre-biopsy prophylactic regimens. Therefore, increasing antibiotic resistance may impact on clinical care, which probably results in differences between hospitals. The objective of our study is to determine the (variability in) current practices of PB in the Netherlands and to gain insight into Dutch urologists' perceptions of fluoroquinolone resistance and biopsy related infections. METHODS: An online questionnaire was prepared using SurveyMonkey® platform and distributed to all 420 members of the Dutch Association of Urology, who work in 81 Dutch hospitals. Information about PB techniques and periprocedural antimicrobial prophylaxis was collected. Urologists' perceptions regarding pre-biopsy antibiotic prophylaxis in an era of antibiotic resistance was assessed. Descriptive statistical analysis was performed. RESULTS: One hundred sixty-one responses (38.3%) were analyzed representing 65 (80.3%) of all Dutch hospitals performing PB. Transrectal ultrasound guided prostate biopsy (TRUSPB) was performed in 64 (98.5%) hospitals. 43.1% of the hospitals (also) used other image-guided biopsy techniques. Twenty-three different empirical prophylactic regimens were reported among the hospitals. Ciprofloxacin was most commonly prescribed (84.4%). The duration ranged from one pre-biopsy dose (59.4%) to 5 days extended prophylaxis. 25.2% of the urologists experienced ciprofloxacin resistance as a current problem in the prevention of biopsy related infections and 73.6% as a future problem. CONCLUSIONS: There is a wide variation in practice patterns among Dutch urologists. TRUSPB is the most commonly used biopsy technique, but other image-guided biopsy techniques are increasingly used. Antimicrobial prophylaxis is not standardized and prolonged prophylaxis is common. The wide variation in practice patterns and lack of standardization underlines the need for evidence-based recommendations to guide urologists in choosing appropriate antimicrobial prophylaxis for PB in the context of increasing antibiotic resistance.

Development of an algorithm to discriminate between plasmid- and chromosomal-mediated AmpC ß-lactamase production in Escherichia coli by elaborate phenotypic and genotypic characterization.

OBJECTIVES: AmpC-ß-lactamase production is an under-recognized antibiotic resistance mechanism that renders Gram-negative bacteria resistant to common ß-lactam antibiotics, similar to the well-known ESBLs. For infection control purposes, it is important to be able to discriminate between plasmid-mediated AmpC (pAmpC) production and chromosomal-mediated AmpC (cAmpC) hyperproduction in Gram-negative bacteria as pAmpC requires isolation precautions to minimize the risk of horizontal gene transmission. Detecting pAmpC in Escherichia coli is challenging, as both pAmpC production and cAmpC hyperproduction may lead to third-generation cephalosporin resistance. METHODS: We tested a collection of E. coli strains suspected to produce AmpC. Elaborate susceptibility testing for third-generation cephalosporins, WGS and machine learning were used to develop an algorithm to determine ampC genotypes in E. coli. WGS was applied to detect pampC genes, cAmpC hyperproducers and STs. RESULTS: In total, 172 E. coli strains (n=75 ST) were divided into a training set and two validation sets. Ninety strains were pampC positive, the predominant gene being blaCMY-2 (86.7%), followed by blaDHA-1 (7.8%), and 59 strains were cAmpC hyperproducers. The algorithm used a cefotaxime MIC value above 6 mg/L to identify pampC-positive E. coli and an MIC value of 0.5 mg/L to discriminate between cAmpC-hyperproducing and non-cAmpC-hyperproducing E. coli strains. Accuracy was 0.88 (95% CI=0.79-0.94) on the training set, 0.79 (95% CI=0.64-0.89) on validation set 1 and 0.85 (95% CI=0.71-0.94) on validation set 2. CONCLUSIONS: This approach resulted in a pragmatic algorithm for differentiating ampC genotypes in E. coli based on phenotypic susceptibility testing.

Clinical cure rate and cost-effectiveness of carbapenem-sparing beta-lactams vs. meropenem for Gram-negative infections: A systematic review, meta-analysis, and cost-effectiveness analysis.

The increasing incidence of infections caused by extended-spectrum beta-lactamase (ESBL)/AmpC-producing bacteria leads to increasing use of carbapenems and risk of carbapenem resistance. Treatment success of carbapenem-sparing beta-lactams (CSBs) for ESBL infections is unclear. The aim of this study was to appraise the clinical cure rate and estimate the cost-effectiveness of meropenem vs. CSBs (piperacillin-tazobactam, temocillin, ceftazidime-avibactam, and ceftolozane-tazobactam) for urinary tract infections (UTIs) or intra-abdominal infections (IAIs) due to ESBL/AmpC-producing bacteria. A systematic literature search of the Cochrane library, EMBASE, PubMed, and Web of Science was conducted to identify studies assessing the clinical cure rate of the antibiotics. To assess the cost-effectiveness of CSBs vs. meropenem, a combined decision analytic and Markov model was probabilistically analysed over a 5-year period. The main outcome was presented as the incremental cost-effectiveness ratio and evaluated with a threshold of €20 000 per life year gained (LYG). From 656 identified articles, 17 and 14 studies were included in the qualitative synthesis and quantitative synthesis, respectively. A clinical cure of ceftazidime-avibactam and ceftolozane-tazobactam was comparable to meropenem in patients with complicated IAIs (cIAIs) due to ESBL (Risk ratio [RR]=1·04, 95% confidence interval [CI]=0·95-1·13). Both temocillin and ceftolozane-tazobactam were deemed cost-effective compared to meropenem with €157·58 and €13 398·34 per LYG, respectively, in patients with UTIs due to ESBL. However, only ceftazidime-avibactam (plus metronidazole) was cost-effective for the treatment of IAIs, with €16 916·77 per LYG. These results show that several CSBs can be considered as viable candidates for the treatment of UTIs and IAIs caused by ESBL.

In Vitro Activity of Chlorhexidine Compared with Seven Antifungal Agents against 98 Fusarium Isolates Recovered from Fungal Keratitis Patients.

Fungal keratitis is a common but severe eye infection in tropical and subtropical areas of the world. In regions with a temperate climate, the frequency of infection is rising in patients with contact lenses and following trauma. Early and adequate therapy is important to prevent disease progression and loss of vision. The management of Fusarium keratitis is complex, and the optimal treatment is not well defined. We investigated the in vitro activity of chlorhexidine and seven antifungal agents against a well-characterized collection of Fusarium isolates recovered from patients with Fusarium keratitis. The fungus culture collection of the Center of Expertise in Mycology Radboudumc/CWZ was searched for Fusarium isolates that were cultured from cornea scrapings, ocular biopsy specimens, eye swabs, and contact lens fluid containers from patients with suspected keratitis. The Fusarium isolates that were cultured from patients with confirmed keratitis were all identified using conventional and molecular techniques. Antifungal susceptibility testing was performed according to the EUCAST broth microdilution reference method. The antifungal agents tested included amphotericin B, voriconazole, posaconazole, miconazole, natamycin, 5-fluorocytosine, and caspofungin. In addition, the activity of chlorhexidine was determined. The fungal culture collection contained 98 Fusarium isolates of confirmed fungal keratitis cases from 83 Dutch patients and 15 Tanzanian patients. The isolates were collected between 2007 and 2017. Fusarium oxysporum (n = 24, 24.5%) was the most frequently isolated species followed by Fusarium solanisensu stricto (n = 18, 18.4%) and Fusarium petroliphilum (n = 11, 11.2%). Amphotericin B showed the most favorable in vitro inhibition of Fusarium species followed by natamycin, voriconazole, and chlorhexidine, while 5-fluorocytosine, posaconazole, miconazole, and caspofungin showed no relevant inhibiting effect. However, chlorhexidine showed fungicidal activity against 90% of F. oxysporum strains and 100% of the F. solani strains. Our study supports the clinical efficacy of chlorhexidine and therefore warrants its further clinical evaluation for primary therapy of fungal keratitis, particularly in low and middle income countries where fungal keratitis is much more frequent and, currently, antifungal eye drops are often unavailable.

Quantification of viable bacterial load in artificial sputum spiked with Mycobacterium tuberculosis.

OBJECTIVE: Artificial sputum spiked with Mycobacterium tuberculosis could serve for validation of procedures that determine viable mycobacterial load. DESIGN: Artificial sputum specimens prepared in-house were spiked with low, medium or high concentrations of Mycobacterium tuberculosis H37Rv stock solution. In a first series, a single technologist processed two batches of specimens daily with high load that were stored refrigerated or at room temperature for up to 8 days. In a second series, nine different technologists processed freshly made batches of specimens with low, medium or high loads. We recorded time to positivity (TTP) in duplicate liquid cultures made from each specimen. RESULTS: Specimens were well grouped around the mean TTP (hours; standard deviation) of low: 271.7 (25.9), medium: 233.5 (16.3), and two batches of high load: 186.9 (12.3) and 191.8 (9.0), respectively. A variance component model that included load, storage temperature, days of storage until processing, batch of specimens made, sample ID and technologist ID as random effects in a linear mixed-effects model identified only load, technologist and residual as significant contributors to overall TTP variance. CONCLUSION: Artificial sputum specimens with reproducible and stable viable mycobacterial loads can be made that could serve for training and validation purposes.