Enhancement and Comparison of (Ceftazidime-)Avibactam Plus Aztreonam Susceptibility Tests for Stenotrophomonas maltophilia in Clinical Diagnostics.

Stenotrophomonas maltophilia is naturally resistant to many antimicrobials. We evaluated the in vitro activity and reproducibility of two different super-position methods of aztreonam in combination with ceftazidime-avibactam for S. maltophilia and compared these results with the recently available aztreonam-avibactam gradient strip. We recommend an improved super-position method that avoids the possible risk of handling a contaminated aztreonam strip. In addition, we report that the cefazidime-avibactam and aztreonam super-position method showed increased in vitro activity in comparison with aztreonam-avibactam indicating activity of the ceftazidime component in vitro.

Clinical Impact of Polymerase Chain Reaction-Based Aspergillus and Azole Resistance Detection in Invasive Aspergillosis: A Prospective Multicenter Study.

BACKGROUND: Invasive aspergillosis (IA) by a triazole-resistant Aspergillus fumigatus is associated with high mortality. Real-time resistance detection will result in earlier initiation of appropriate therapy. METHODS: In a prospective study, we evaluated the clinical value of the AsperGenius polymerase chain reaction (PCR) assay in hematology patients from 12 centers. This PCR assay detects the most frequent cyp51A mutations in A. fumigatus conferring azole resistance. Patients were included when a computed tomography scan showed a pulmonary infiltrate and bronchoalveolar fluid (BALf) sampling was performed. The primary end point was antifungal treatment failure in patients with azole-resistant IA. RESULTS: Of 323 patients enrolled, complete mycological and radiological information was available for 276 (94%), and probable IA was diagnosed in 99/276 (36%). Sufficient BALf for PCR testing was available for 293/323 (91%). Aspergillus DNA was detected in 116/293 (40%) and A. fumigatus DNA in 89/293 (30%). The resistance PCR was conclusive in 58/89 (65%) and resistance detected in 8/58 (14%). Two had a mixed azole-susceptible/azole-resistant infection. In the 6 remaining patients, treatment failure was observed in 1. Galactomannan positivity was associated with mortality (P = .004) while an isolated positive Aspergillus PCR was not (P = .83). CONCLUSIONS: Real-time PCR-based resistance testing may help to limit the clinical impact of triazole resistance. In contrast, the clinical impact of an isolated positive Aspergillus PCR on BALf seems limited. The interpretation of the EORTC/MSGERC PCR criterion for BALf may need further specification (eg, minimum cycle threshold value and/or PCR positive on >1 BALf sample).

Quality of MALDI-TOF mass spectra in routine diagnostics: results from an international external quality assessment including 36 laboratories from 12 countries using 47 challenging bacterial strains.

OBJECTIVES: Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a widely used method for bacterial species identification. Incomplete databases and mass spectral quality (MSQ) still represent major challenges. Important proxies for MSQ are the number of detected marker masses, reproducibility, and measurement precision. We aimed to assess MSQs across diagnostic laboratories and the potential of simple workflow adaptations to improve it. METHODS: For baseline MSQ assessment, 47 diverse bacterial strains, which are challenging to identify by MALDI-TOF MS, were routinely measured in 36 laboratories from 12 countries, and well-defined MSQ features were used. After an intervention consisting of detailed reported feedback and instructions on how to acquire MALDI-TOF mass spectra, measurements were repeated and MSQs were compared. RESULTS: At baseline, we observed heterogeneous MSQ between the devices, considering the median number of marker masses detected (range = [2-25]), reproducibility between technical replicates (range = [55%-86%]), and measurement error (range = [147 parts per million (ppm)-588 ppm]). As a general trend, the spectral quality was improved after the intervention for devices, which yielded low MSQs in the baseline assessment as follows: for four out of five devices with a high measurement error, the measurement precision was improved (p-values <0.001, paired Wilcoxon test); for six out of ten devices, which detected a low number of marker masses, the number of detected marker masses increased (p-values <0.001, paired Wilcoxon test). DISCUSSION: We have identified simple workflow adaptations, which, to some extent, improve MSQ of poorly performing devices and should be considered by laboratories yielding a low MSQ. Improving MALDI-TOF MSQ in routine diagnostics is essential for increasing the resolution of bacterial identification by MALDI-TOF MS, which is dependent on the reproducible detection of marker masses. The heterogeneity identified in this external quality assessment (EQA) requires further study.

A high prevalence of Cutibacterium acnes infections in scoliosis revision surgery, a diagnostic and therapeutic dilemma.

PURPOSE: To investigate if serum inflammatory markers or nuclear imaging can accurately diagnose a chronic spinal instrumentation infection (SII) prior to surgery. METHODS: All patients who underwent revision of spinal instrumentation after a scoliosis correction between 2017 and 2019, were retrospectively evaluated. The diagnostic accuracy of serum C-reactive protein (CRP) and Erythrocyte Sedimentation Rate (ESR), 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) and Technetium-99m-methylene diphosphonate (99mTc-MDP) 3-phase bone scintigraphy (TPBS) to diagnose infection were studied. Patients with an acute infection or inadequate culture sampling were excluded. SII was diagnosed if ≥ 2 of the same microorganism(s) were isolated from intra-operative tissue cultures. RESULTS: 30 patients were included. The indication for revision surgery was pseudoarthrosis in the majority of patients (n = 15). 22 patients (73%) were diagnosed with SII. In all infected cases, Cutibacterium acnes was isolated, including 5 cases with a polymicrobial infection. The majority of patients had low inflammatory parameters preoperatively. For CRP > 10.0 mg/L, the sensitivity was 9.1% and specificity 100%; for ESR > 30 mm/h, the sensitivity was 9.1% and specificity 100%. The diagnostic accuracy for nuclear imaging was 64% for the FDG-PET/CT and 67% for the TPBS to diagnose infection. CONCLUSIONS: The prevalence of SII in patients undergoing revision spinal surgery is high, with Cutibacterium acnes as the main pathogen. No diagnostic tests could be identified that could accurately diagnose or exclude SII prior to surgery. Future studies should aim to find more sensitive diagnostic modalities to detect low-grade inflammation.

Whole-genome sequence-informed MALDI-TOF MS diagnostics reveal importance of Klebsiella oxytoca group in invasive infections: a retrospective clinical study.

BACKGROUND: Klebsiella spp. are opportunistic pathogens which can cause severe infections, are often multi-drug resistant and are a common cause of hospital-acquired infections. Multiple new Klebsiella species have recently been described, yet their clinical impact and antibiotic resistance profiles are largely unknown. We aimed to explore Klebsiella group- and species-specific clinical impact, antimicrobial resistance (AMR) and virulence. METHODS: We analysed whole-genome sequence data of a diverse selection of Klebsiella spp. isolates and identified resistance and virulence factors. Using the genomes of 3594 Klebsiella isolates, we predicted the masses of 56 ribosomal subunit proteins and identified species-specific marker masses. We then re-analysed over 22,000 Matrix-Assisted Laser Desorption Ionization - Time Of Flight (MALDI-TOF) mass spectra routinely acquired at eight healthcare institutions in four countries looking for these species-specific markers. Analyses of clinical and microbiological endpoints from a subset of 957 patients with infections from Klebsiella species were performed using generalized linear mixed-effects models. RESULTS: Our comparative genomic analysis shows group- and species-specific trends in accessory genome composition. With the identified species-specific marker masses, eight Klebsiella species can be distinguished using MALDI-TOF MS. We identified K. pneumoniae (71.2%; n = 12,523), K. quasipneumoniae (3.3%; n = 575), K. variicola (9.8%; n = 1717), "K. quasivariicola" (0.3%; n = 52), K. oxytoca (8.2%; n = 1445), K. michiganensis (4.8%; n = 836), K. grimontii (2.4%; n = 425) and K. huaxensis (0.1%; n = 12). Isolates belonging to the K. oxytoca group, which includes the species K. oxytoca, K. michiganensis and K. grimontii, were less often resistant to 4th-generation cephalosporins than isolates of the K. pneumoniae group, which includes the species K. pneumoniae, K. quasipneumoniae, K. variicola and "K. quasivariicola" (odds ratio = 0.17, p < 0.001, 95% confidence interval [0.09,0.28]). Within the K. pneumoniae group, isolates identified as K. pneumoniae were more often resistant to 4th-generation cephalosporins than K. variicola isolates (odds ratio = 2.61, p = 0.003, 95% confidence interval [1.38,5.06]). K. oxytoca group isolates were found to be more likely associated with invasive infection to primary sterile sites than K. pneumoniae group isolates (odds ratio = 2.39, p = 0.0044, 95% confidence interval [1.05,5.53]). CONCLUSIONS: Currently misdiagnosed Klebsiella spp. can be distinguished using a ribosomal marker-based approach for MALDI-TOF MS. Klebsiella groups and species differed in AMR profiles, and in their association with invasive infection, highlighting the importance for species identification to enable effective treatment options.

Absence of Host-Specific Genes in Canine and Human Staphylococcus pseudintermedius as Inferred from Comparative Genomics.

Staphylococcus pseudintermedius is an important pathogen in dogs that occasionally causes infections in humans as an opportunistic pathogen of elderly and immunocompromised people. This study compared the genomic relatedness and antimicrobial resistance genes using genome-wide association study (GWAS) to examine host association of canine and human S. pseudintermedius isolates. Canine (n = 25) and human (n = 32) methicillin-susceptible S. pseudintermedius (MSSP) isolates showed a high level of genetic diversity with an overrepresentation of clonal complex CC241 in human isolates. This clonal complex was associated with carriage of a plasmid containing a bacteriocin with cytotoxic properties, a CRISPR-cas domain and a pRE25-like mobile element containing five antimicrobial resistance genes. Multi-drug resistance (MDR) was predicted in 13 (41%) of human isolates and 14 (56%) of canine isolates. CC241 represented 54% of predicted MDR isolates from humans and 21% of predicted MDR canine isolates. While it had previously been suggested that certain host-specific genes were present the current GWAS analysis did not identify any genes that were significantly associated with human or canine isolates. In conclusion, this is the first genomic study showing that MSSP is genetically diverse in both hosts and that multidrug resistance is important in dog and human-associated S. pseudintermedius isolates.

Should all hip and knee prosthetic joints be aspirated prior to revision surgery?

AIMS: It is essential to exclude a periprosthetic joint infection (PJI) prior to revision surgery. It is recommended to routinely aspirate the joint before surgery. However, this may not be necessary in a subgroup of patients. The aim of our study was to investigate if specific clinical and implant characteristics could be identified to rule out a PJI prior to revision surgery. METHODS: We retrospectively evaluated clinical and implant characteristics of patients who underwent a hip or knee revision surgery between October 2015 and October 2018. Patients were diagnosed with a PJI according to the MSIS diagnostic criteria. RESULTS: A total of 156 patients were analyzed, including 107 implants that were revised because of prosthetic loosening and 49 because of mechanical failure (i.e. instability, malalignment or malpositioning). No PJI was diagnosed in the group with mechanical failure. In the prosthetic loosening group, 20 of 107 were diagnosed with a PJI (19%). Although there was a significantly lower chance of having a PJI with an implant age of > 5 years combined with a CRP < 5 mg/L, an infection was still present in 3 out of 39 cases (8%). CONCLUSION: Implants with solely mechanical failure without signs of loosening and low inflammatory parameters probably do not require a synovial fluid aspiration. These results need to be confirmed in a larger cohort of patients. In case of prosthetic loosening, all joints need to be aspirated before surgery as no specific characteristic could be identified to rule out an infection.

Paradoxal Trends in Azole-Resistant Aspergillus fumigatus in a National Multicenter Surveillance Program, the Netherlands, 2013-2018.

We investigated the prevalence of azole resistance of Aspergillus fumigatus isolates in the Netherlands by screening clinical A. fumigatus isolates for azole resistance during 2013-2018. We analyzed azole-resistant isolates phenotypically by in vitro susceptibility testing and for the presence of resistance mutations in the Cyp51A gene. Over the 6-year period, 508 (11%) of 4,496 culture-positive patients harbored an azole-resistant isolate. Resistance frequency increased from 7.6% (95% CI 5.9%-9.8%) in 2013 (58/760 patients) to 14.7% (95% CI 12.3%-17.4%) in 2018 (112/764 patients) (p = 0.0001). TR34/L98H (69%) and TR46/Y121F/T289A (17%) accounted for 86% of Cyp51A mutations. However, the mean voriconazole MIC of TR34/L98H isolates decreased from 8 mg/L (2013) to 2 mg/L (2018), and the voriconazole-resistance frequency was 34% lower in 2018 than in 2013 (p = 0.0001). Our survey showed changing azole phenotypes in TR34/L98H isolates, which hampers the use of current PCR-based resistance tests.

Obese patients have higher rates of polymicrobial and Gram-negative early periprosthetic joint infections of the hip than non-obese patients.

BACKGROUND: Obese patients are more likely to develop periprosthetic joint infection (PJI) after primary total joint arthroplasty. This study compared the clinical and microbiological characteristics of non-obese, obese and severely obese patients with early PJI, in order to ultimately optimize antibiotic prophylaxis and other prevention measures for this specific patient category. METHODS: We retrospectively evaluated patients with early PJI of the hip and knee treated with debridement, antibiotics and implant retention (DAIR) between 2006 and 2016 in three Dutch hospitals. Only patients with primary arthroplasties indicated for osteoarthritis were included. Early PJI was defined as an infection that developed within 90 days after index surgery. Obesity was defined as a BMI ≥30kg/m2 and severe obesity as a BMI ≥35kg/m2. RESULTS: A total of 237 patients were analyzed, including 64 obese patients (27.0%) and 62 severely obese patients (26.2%). Compared with non-obese patients, obese patients had higher rates of polymicrobial infections (60.3% vs 33.3%, p<0.001) with more often involvement of Enterococcus species (27.0% vs 11.7%, p = 0.003). Moreover, severely obese patients had more Gram-negative infections, especially with Proteus species (12.9% vs 2.3%, p = 0.001). These results were only found in periprosthetic hip infections, comprising Gram-negative PJIs in 34.2% of severely obese patients compared with 24.7% in obese patients and 12.7% in non-obese patients (p = 0.018). CONCLUSIONS: Our results demonstrate that obese patients with early periprosthetic hip infections have higher rates of polymicrobial infections with enterococci and Gram-negative rods, which stresses the importance of improving preventive strategies in this specific patient category, by adjusting antibiotic prophylaxis regimens, improving disinfection strategies and optimizing postoperative wound care.

18F-FDG-PET uptake in non-infected total hip prostheses.

Background and purpose - 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) can be used in the diagnostic work-up of a patient with suspected periprosthetic joint infection (PJI) but, due to a lack of accurate interpretation criteria, this technique is not routinely applied. Since the physiological uptake pattern of FDG around a joint prosthesis is not fully elucidated, we determined the physiological FDG uptake in non-infected total hip prostheses. Patients and methods - Patients treated with primary total hip arthroplasty (1995-2016) who underwent a FDG-PET/CT for an indication other than a suspected PJI were retrospectively evaluated. Scans were both visually and quantitatively analyzed. Semi-quantitative analysis was performed by calculating maximum and peak standardized uptake values (SUVmax and SUVpeak) by volume of interests (VOIs) at 8 different locations around the prosthesis. Results - 58 scans from 30 patients were analyzed. In most hips, a diffuse heterogeneous uptake pattern around the prosthesis was observed (in 32/38 of the cemented prostheses, and in 16/20 of the uncemented prostheses) and most uptake was located around the neck of the prosthesis. The median SUVmax in the cemented group was 2.66 (95% CI 2.51-3.10) and in the uncemented group 2.87 (CI 2.65-4.63) (Median difference = -0.36 [CI -1.2 to 0.34]). In uncemented prostheses, there was a positive correlation in time between the age of the prosthesis and the FDG uptake (rs = 0.63 [CI 0.26-0.84]). Interpretation - Our study provides key data to develop accurate interpretation criteria to differentiate between physiological uptake and infection in patients with a prosthetic joint.

Use of gentamicin-impregnated beads or sponges in the treatment of early acute periprosthetic joint infection: a propensity score analysis.

Objectives: Early acute periprosthetic joint infections (PJIs) treated with debridement, antibiotics and implant retention (DAIR) have failure rates ranging from 10% to 60%. We determined the efficacy of applying local gentamicin-impregnated beads and/or sponges during debridement in early PJI. Methods: Patients with early acute PJI, defined as less than 21 days of symptoms and treated with DAIR within 90 days after index surgery, were retrospectively evaluated. Early failure was defined as PJI-related death, the need for implant removal or a second DAIR or antibiotic suppressive therapy owing to persistent signs of infection, all within 60 days after initial debridement. Overall failure was defined as implant removal at any timepoint during follow-up. A 1:1 propensity score matching was performed to correct for confounding factors. Results: A total of 386 patients were included. Local gentamicin was applied in 293 patients (75.9%) and was withheld in 93 patients (24.1%). Multivariate analysis demonstrated that the use of local gentamicin was independently associated with early failure (OR = 1.97, 95% CI = 1.12-3.48). After propensity matching, early failure was 40.3% in the gentamicin group versus 26.0% in the control group (P = 0.06) and overall failure was 5.2% in the gentamicin group versus 2.6% in the control group (P = 0.40). These numbers remained when solely analysing the application of gentamicin-impregnated sponges. Conclusions: Even after propensity score matching, failure rates remained higher if local gentamicin-impregnated beads and/or sponges were administered in early acute PJI. Based on these results, their use should be discouraged.

Sonication of heart valves detects more bacteria in infective endocarditis.

Optimal antimicrobial treatment of infective endocarditis requires identification and susceptibility patterns of pathogens. Sonication of explanted heart valves could increase the identification and culture of pathogens, as shown in prosthetic joint and pacemaker/ICD infections. We tested 26 explanted heart valves from 20 patients with active definite endocarditis for added diagnostic value of sonication to the standard microbiological workup in a prospective diagnostic proof of concept study. Two sonication protocols (broth enrichment vs. centrifugation) were compared in an additional 35 negative control valves for contamination rates. We selected sonication/centrifugation based on acceptable false positive rates (11.4%; 4/35). Sonication/enrichment yielded many false positive results in negative controls (28.6%; 10/35), mainly Propionibacterium acnes (next-generation sequencing excluded technical problems). Compared to direct culture only, adding sonication/centrifugation (including molecular testing) significantly increased the diagnostic yield from 6/26 to 17/26 valves (p = 0.003). Most importantly, culture positives almost doubled (from 6 to 10), providing unique quantitative information about antimicrobial susceptibility. Even if direct molecular testing was added to the standard workup, sonication/centrifugation provided additional diagnostic information in a significant number of valves (8/26; 31%; p = 0.013). We concluded that sonication/centrifugation added relevant diagnostic information in the workup of heart valves with infective endocarditis, with acceptable contamination rates.

The diagnosis and treatment of invasive aspergillosis in Dutch haematology units facing a rapidly increasing prevalence of azole-resistance. A nationwide survey and rationale for the DB-MSG 002 study protocol.

Patients with haematological malignancies are at risk for invasive fungal diseases (IFD). A survey was conducted in all Dutch academic haematology centres on their current diagnostic, prophylactic and therapeutic approach towards IFD in the context of azole-resistance. In all 8 centres, a haematologist and microbiologist filled in the questionnaire that focused on different subgroups of haematology patients. Fungal prophylaxis during neutropaenia was directed against Candida and consisted of fluconazole and/or amphotericin B suspension. Mould-active prophylaxis was given to acute myeloid leukaemia patients during chemotherapy in 2 of 8 centres. All centres used azole prophylaxis in a subset of patients with graft-versus-host disease. A uniform approach towards the diagnosis and treatment of IFD and in particular azole-resistant Aspergillus fumigatus was lacking. In 2017, all centres agreed to implement a uniform diagnostic and treatment algorithm regarding invasive aspergillosis with a central role for comprehensive diagnostics and PCR-based detection of azole-resistance. This study (DB-MSG 002) will re-evaluate this algorithm when 280 patients have been treated. A heterogeneous approach towards antifungal prophylaxis, diagnosis and treatment was apparent in the Netherlands. Facing triazole-resistance, consensus was reached on the implementation of a uniform diagnostic approach in all 8 centres.

Puncture Protocol in the Diagnostic Work-Up of a Suspected Chronic Prosthetic Joint Infection of the Hip.

BACKGROUND: Diagnosing a chronic prosthetic joint infection (PJI) can be challenging. We hypothesized that obtaining preoperative tissue samples for culture in hip arthroplasty will increase the likelihood of diagnosing an infection before revision surgery. The aim of this cohort study was to determine the diagnostic accuracy of 2 tissue acquiring biopsy strategies to diagnose a PJI. METHODS: Patients with a painful hip arthroplasty, in which a chronic PJI was suspected, were included. Tissue samples were obtained either by ultrasound guidance with a 16-Gauge needle (2012-2013) or in the operating room with a thick-bore needle (2013-2016). Revision surgery tissue biopsies were used as the gold standard. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were calculated. RESULTS: A total of 16 patients in the ultrasound cohort and 29 patients in the surgical cohort were included. Thirty-one percent (n = 14) were finally diagnosed with a PJI. The addition of thick bore needle tissue biopsies resulted in 9% more diagnosed PJIs compared with synovial fluid alone. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio was 33%, 85%, 33%, 85%, 2.2, and 0.8, respectively, for the ultrasound-guided biopsy cohort and 82%, 100%, 100%, 90%, infinite, and 0.2, respectively, for the surgical biopsy cohort. CONCLUSION: Obtaining multiple good quality tissue biopsies in a sterile environment will contribute to the diagnosis of a chronic PJI of the hip, with a higher diagnostic accuracy compared with ultrasound-guided thin needle biopsies and compared with synovial fluid culture alone.

Synovial Calprotectin: An Inexpensive Biomarker to Exclude a Chronic Prosthetic Joint Infection.

BACKGROUND: To diagnose or exclude a chronic prosthetic joint infection (PJI) can be a clinical challenge. Therefore, sensitive and specific biomarkers are needed in the diagnostic work-up. Calprotectin is a protein with antimicrobial properties and is released by activated neutrophils, making it a specific marker for infection. Because of its low costs and ability to obtain a quantitative value as a point of care test, it is an attractive marker to use in clinical practice. In addition, the test is already used in routine care in most hospitals for other indications and therefore easy to implement. METHODS: Between June 2015 and June 2017 we collected synovial fluid of all consecutive patients who underwent revision surgery of a prosthetic joint because of chronic pain with or without prosthetic loosening. Synovial calprotectin was measured using a lateral flow immunoassay. A PJI was defined by the diagnostic criteria described by the Musculoskeletal Infection Society. RESULTS: Fifty-two patients with chronic pain were included. A PJI was diagnosed in 15 of 52 (29%) patients. The median calprotectin in the PJI group was 859 mg/L (interquartile range 86-1707) vs 7 mg/L (interquartile range 3-25) in the control group (P < .001). With a cut-off value of 50 mg/L, synovial calprotectin showed a sensitivity, specificity, positive predictive value, and negative predictive value of 86.7%, 91.7%, 81.3%, and 94.4%, respectively. CONCLUSION: Synovial calprotectin is a useful and cheap biomarker to use in the diagnostic work-up of patients with chronic pain, especially to exclude a PJI prior to revision surgery.

Moxifloxacin plus rifampin as an alternative for levofloxacin plus rifampin in the treatment of a prosthetic joint infection with Staphylococcus aureus.

OBJECTIVES: The combination of a fluoroquinolone with rifampin is one of the cornerstones in the treatment of prosthetic joint infections (PJI) caused by staphylococci. Moxifloxacin is highly active against methicillin-susceptible Staphylococcus aureus (MSSA) and, therefore, is an attractive agent to use. However, several studies reported a lowering in serum moxifloxacin levels when combined with rifampin. The clinical relevance remains unclear. We determined the outcome of patients with early acute PJI caused by MSSA treated with either moxifloxacin/rifampin or levofloxacin/rifampin. METHODS: Medical files of patients treated with moxifloxacin/rifampin (University Medical Centre Groningen) or levofloxacin/rifampin (Hospital Clinic Barcelona) were retrospectively reviewed (2005-2015). Treatment failure was defined as the need for revision surgery and/or suppressive therapy, death by infection or a relapse of infection during follow-up. RESULTS: Differences in baseline characteristics between the two cohorts were observed, but prognostic parameters for failure, as defined by the KLIC-score (Kidney failure, Liver cirrhosis, Index surgery, C-reactive protein and Cemented prosthesis), were similar in the two groups (2.9 [1.5 SD] for the moxifloxacin group vs. 2.2 [1.2 SD] for the levofloxacin group [P = 0.16]). With a mean follow-up of 50 months (36 SD) in the moxifloxacin group, and 67 months (50 SD) in the levofloxacin group (P = 0.36), treatment was successful in 89% vs. 87.5%, respectively (P = 0.89). None of the failures in the moxifloxacin group were due to rifampin- or moxifloxacin-resistant S. aureus strains. CONCLUSION: Our data indicate that moxifloxacin combined with rifampin is as clinically effective as levofloxacin/rifampin for early acute PJI caused by MSSA.

Ribotype 078 Clostridium difficile infection incidence in Dutch hospitals is not associated with provincial pig farming: Results from a national sentinel surveillance, 2009-2015.

BACKGROUND: It has been suggested that the high incidence of ribotype 078 Clostridium difficile infections (CDI) in the Netherlands is related to pig farming. METHODS: We used data of hospitalised CDI patients (>2yrs of age) diagnosed between May 2009 and May 2015 in 26 hospitals participating in a national sentinel surveillance. We compared clinical and geographical characteristics of 078 CDI to other CDI. We investigated the association between 078 CDI incidence and four indicators of pig farming (piglet, pig, piglet farm and pig farm density) by mixed-effects Poisson regression. We used a space-time permutation model to search for community-onset 078 CDI clusters (using SaTScan). RESULTS: A total of 4,691 CDI were identified. Ribotype 078 was isolated in 493 of 3,756 patients (13.1%) including a typing result. These patients had slightly higher community-onset disease and a 35% increase of 30-day mortality compared to non-078 CDI patients. The pooled overall and 078 incidence rates were 2.82 (95% CI, 2.42-3.29) and 0.26 (95% CI, 0.21-0.31) CDI per 10,000 patients-days respectively. Hospital 078 CDI incidence was not associated with provincial pig (IRR, 0.98; 95% CI, 0.89-1.08), piglet (IRR, 0.95; 95% CI, 0.75-1.19), pig farm (IRR, 1.08; 95% CI, 0.84-1.39), or piglet farm density (IRR, 1.00; 95% CI, 0.56-1.79). No clusters of community-onset ribotype 078 CDI were found. CONCLUSIONS: Our results do not indicate that the ribotype 078 CDI incidence in hospitals is related to pig (farm) or piglet (farm) density. However, transmission beyond provincial borders or in non-hospitalised patients cannot be excluded.

Epidemiology of Extended-Spectrum ß-Lactamase-Producing E. coli and Vancomycin-Resistant Enterococci in the Northern Dutch-German Cross-Border Region.

Objectives: To reveal the prevalence and epidemiology of extended-spectrum ß-lactamase (ESBL)- and/or plasmid AmpC (pAmpC)- and carbapenemase (CP) producing Enterobacteriaceae and vancomycin-resistant enterococci (VRE) across the Northern Dutch-German border region. Methods: A point-prevalence study on ESBL/pAmpC/CP producing Enterobacteriaceae and VRE was carried out in hospitalized patients in the Northern Netherlands (n = 445, 2012-2013) and Germany (n = 242, 2012). Healthy individuals from the Dutch community (n = 400, 2010-2012) were also screened. In addition, a genome-wide gene-by-gene approach was applied to study the epidemiology of ESBL-Escherichia coli and VRE. Results: A total of 34 isolates from 27 patients (6.1%) admitted to Dutch hospitals were ESBL/pAmpC positive and 29 ESBL-E. coli, three pAmpC-E. coli, one ESBL-Enterobacter cloacae, and one pAmpC-Proteus mirabilis were found. In the German hospital, 18 isolates (16 E. coli and 2 Klebsiella pneumoniae) from 17 patients (7.7%) were ESBL positive. In isolates from the hospitalized patients CTX-M-15 was the most frequently detected ESBL-gene. In the Dutch community, 11 individuals (2.75%) were ESBL/pAmpC positive: 10 ESBL-E. coli (CTX-M-1 being the most prevalent gene) and one pAmpC E. coli. Six Dutch (1.3%) and four German (3.9%) hospitalized patients were colonized with VRE. Genetic relatedness by core genome multi-locus sequence typing (cgMLST) was found between two ESBL-E. coli isolates from Dutch and German cross-border hospitals and between VRE isolates from different hospitals within the same region. Conclusion: The prevalence of ESBL/pAmpC-Enterobacteriaceae was similar in hospitalized patients across the Dutch-German border region, whereas VRE prevalence was slightly higher on the German side. The overall prevalence of the studied pathogens was lower in the community than in hospitals in the Northern Netherlands. Cross-border transmission of ESBL-E. coli and VRE seems unlikely based on cgMLST analysis, however continuous monitoring is necessary to control their spread and stay informed about their epidemiology.

A Novel Environmental Azole Resistance Mutation in Aspergillus fumigatus and a Possible Role of Sexual Reproduction in Its Emergence.

This study investigated the dynamics of Aspergillus fumigatus azole-resistant phenotypes in two compost heaps with contrasting azole exposures: azole free and azole exposed. After heat shock, to which sexual but not asexual spores are highly resistant, the azole-free compost yielded 98% (49/50) wild-type and 2% (1/50) azole-resistant isolates, whereas the azole-containing compost yielded 9% (4/45) wild-type and 91% (41/45) resistant isolates. From the latter compost, 80% (36/45) of the isolates contained the TR46/Y121F/T289A genotype, 2% (1/45) harbored the TR46/Y121F/M172I/T289A/G448S genotype, and 9% (4/45) had a novel pan-triazole-resistant mutation (TR463/Y121F/M172I/T289A/G448S) with a triple 46-bp promoter repeat. Subsequent screening of a representative set of clinical A. fumigatus isolates showed that the novel TR463 mutant was already present in samples from three Dutch medical centers collected since 2012. Furthermore, a second new resistance mutation was found in this set that harbored four TR46 repeats. Importantly, in the laboratory, we recovered the TR463 mutation from a sexual cross between two TR46 isolates from the same azole-containing compost, possibly through unequal crossing over between the double tandem repeats (TRs) during meiosis. This possible role of sexual reproduction in the emergence of the mutation was further implicated by the high level of genetic diversity of STR genotypes in the azole-containing compost. Our study confirms that azole resistance mutations continue to emerge in the environment and indicates compost containing azole residues as a possible hot spot. Better insight into the biology of environmental resistance selection is needed to retain the azole class for use in food production and treatment of Aspergillus diseases.IMPORTANCE Composting of organic matter containing azole residues might be important for resistance development and subsequent spread of resistance mutations in Aspergillus fumigatus In this article, we show the dominance of azole-resistant A. fumigatus in azole-exposed compost and the discovery of a new resistance mutation with clinical relevance. Furthermore, our study indicates that current fungicide application is not sustainable as new resistance mutations continue to emerge, thereby threatening the use of triazoles in medicine. We provide evidence that the sexual part of the fungal life cycle may play a role in the emergence of resistance mutations because under laboratory conditions, we reconstructed the resistance mutation through sexual crossing of two azole-resistant A. fumigatus isolates derived from the same compost heap. Understanding the mechanisms of resistance selection in the environment is needed to design strategies against the accumulation of resistance mutations in order to retain the azole class for crop protection and treatment of Aspergillus diseases.

Efficacy of Antibiotic Suppressive Therapy in Patients with a Prosthetic Joint Infection.

Introduction: For chronic prosthetic joint infections (PJI), complete removal of the infected prosthesis is necessary in order to cure the infection. Unfortunately, a subgroup of patients is not able to undergo a revision surgery due to high surgical risk. Alternatively, these patients can be treated with antibiotic suppressive therapy (AST) to suppress the infection. Aim: To evaluate the efficacy and tolerability of AST. Methods: We retrospectively collected data (period 2009-2015) from patients with a PJI (of hip, knee or shoulder) who were treated with AST at the University Medical Center Groningen, the Netherlands. AST was defined as antibiotic treatment for PJI that was started after the usual 3 months of antibiotic treatment. The time of follow-up was defined from the time point AST was started. Treatment was considered as failed, when the patient still experienced joint pain, when surgical intervention (debridement, removal, arthrodesis or amputation) was needed to control the infection and/or when death occurred due to the infection. Results: We included 21 patients with a median age of 67 years (range 21 - 88) and with a median follow-up of 21 months (range 3 - 81). Coagulase negative staphylococci (CNS) (n=6), S. aureus (n=6) and polymicrobial flora (n=4) were the most frequently found causative pathogens. Most patients with CNS and S. aureus were treated with minocycline (67%) and clindamycin (83%) as AST, respectively. Overall, treatment was successful in 67% of patients. Failure was due to persistent joint pain (n=1), surgical intervention because of an uncontrolled infection (n=3), and death due the infection (n=3). We observed a treatment success of 90% in patients with a 'standard' prosthesis (n=11), compared to only 50% in patients with a tumor-prosthesis (n=10). Also, treatment was successful in 83% of patients with a CNS as causative microorganism for the infection, compared to 50% in patients with a S. aureus. Patients who failed on AST had a higher ESR in comparison to patients with a successful treatment (mean 73 ± 25SD versus 32 ± 19SD mm/hour (p = 0.007), respectively. 43% of patients experienced side effects and led to a switch of antibiotic treatment or a dose adjustment in almost all of these patients. Conclusions: Removal of the implant remains first choice in patients with chronic PJI. However, AST is a reasonable alternative treatment option in a subgroup of patients with a PJI who are no candidate for revision surgery, in particular in patients with a 'standard' prosthesis and/or CNS as the causative micro-organism.