Rates of bacterial co-infections and antimicrobial use in COVID-19 patients: a retrospective cohort study in light of antibiotic stewardship.

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. Bacterial co-infections are associated with unfavourable outcomes in respiratory viral infections; however, microbiological and antibiotic data related to COVID-19 are sparse. Adequate use of antibiotics in line with antibiotic stewardship (ABS) principles is warranted during the pandemic. We performed a retrospective study of clinical and microbiological characteristics of 140 COVID-19 patients admitted between February and April 2020 to a German University hospital, with a focus on bacterial co-infections and antimicrobial therapy. The final date of follow-up was 6 May 2020. Clinical data of 140 COVID-19 patients were recorded: The median age was 63.5 (range 17-99) years; 64% were males. According to the implemented local ABS guidelines, the most commonly used antibiotic regimen was ampicillin/sulbactam (41.5%) with a median duration of 6 (range 1-13) days. Urinary antigen tests for Legionella pneumophila and Streptococcus peumoniae were negative in all cases. In critically ill patients admitted to intensive care units (n = 50), co-infections with Enterobacterales (34.0%) and Aspergillus fumigatus (18.0%) were detected. Blood cultures collected at admission showed a diagnostic yield of 4.2%. Bacterial and fungal co-infections are rare in COVID-19 patients and are mainly prevalent in critically ill patients. Further studies are needed to assess the impact of antimicrobial therapy on therapeutic outcome in COVID-19 patients to prevent antimicrobial overuse. ABS guidelines could help in optimising the management of COVID-19. Investigation of microbial patterns of infectious complications in critically ill COVID-19 patients is also required.

Prevalence of third-generation cephalosporin-resistant Enterobacterales colonization on hospital admission and ESBL genotype-specific risk factors: a cross-sectional study in six German university hospitals.

OBJECTIVES: To assess the admission prevalence of third-generation cephalosporin-resistant Enterobacterales (3GCREB) and to assess whether risk factors vary by ß-lactamase genotype. METHODS: Adult patients were recruited within 72 h of admission to general wards of six university hospitals in 2014 and 2015. Rectal swabs were screened for 3GCREB and isolates were analysed phenotypically and genotypically. Patients were questioned on potential risk factors. Multivariable analyses were performed to identify risk factors for 3GCREB colonization and for specific ß-lactamases. RESULTS: Of 8753 patients screened, 828 were 3GCREB positive (9.5%). Eight hundred and thirteen isolates were available for genotyping. CTX-M-15 was the most common ESBL (38.0%), followed by CTX-M-1 (22.5%), CTX-M-14 (8.7%), CTX-M-27 (7.5%) and SHV-ESBL (4.4%). AmpC was found in 11.9%. Interestingly, 18 Escherichia coli isolates were AmpC positive, 12 of which (67%) contained AmpC on a gene of plasmid origin [CMY (n = 10), DHA (n = 2)]. Risk factors for 3GCREB colonization varied by genotype. Recent antibiotic exposure and prior colonization by antibiotic-resistant bacteria were risk factors for all ß-lactamases except CTX-M-14 and CTX-M-27. Travel outside Europe was a risk factor for CTX-M-15 and CTX-M-27 [adjusted OR (aOR) 3.49, 95% CI 2.88-4.24 and aOR 2.73, 95% CI 1.68-4.43]. A previous stay in a long-term care facility was associated with CTX-M-14 (aOR 3.01, 95% CI 1.98-4.59). A preceding hospital stay in Germany increased the risk of CTX-M-15 (aOR 1.27, 95% CI 1.14-1.41), while a prior hospital stay in other European countries increased the risk of SHV-ESBL colonization (aOR 3.85, 95% CI 1.67-8.92). CONCLUSIONS: The detection of different ESBL types is associated with specific risk factor sets that might represent distinct sources of colonization and ESBL-specific dissemination routes.

Value of multiplex PCR for detection of antimicrobial resistance in samples retrieved from patients with orthopaedic infections.

BACKGROUND: The performance of multiplex PCR (mPCR) for detection of antimicrobial resistance from clinical isolates is unknown. We assessed the ability of mPCR to analyse resistance genes directly from clinical samples. Patients with orthopedic infections were prospectively included. Phenotypical and genotypical resistance was evaluated in clinical samples (synovial and sonication fluid) where identical pathogens were identified by culture and mPCR. RESULT: A total of 94 samples were analysed, including 60 sonication fluid and 34 synovial fluid samples. For coagulase-negative staphylococcus strains, mPCR detected resistance to oxacillin in 10 of 23 isolates (44%) and to rifampin in none of 6 isolates. For S. aureus isolates, detection rate of oxacillin and rifampin-resistance was 100% (2/2 and 1/1, respectively). Fluoroquinolone-resistance was confirmed by mPCR in all 3 isolates of Enterobacteriaceae, in enterococci resistance to aminoglycoside-high level was detected in 1 of 3 isolates (33%) and in streptococci resistance to macrolides/lincosamides in none of 2 isolates. The overall sensitivity for different pathogens and antimicrobials was 46% and specificity 95%, the median concordance was 80% (range, 57-100%). Full agreement was observed for oxacillin in S. aureus, vancomycin in enterococci, carbapenems/cephalosporins in Enterobacteriaceae and rifampin in Cutibacterium species. CONCLUSION: The overall sensitivity for detection of antimicrobial resistance by mPCR directly from clinical samples was low. False-negative mPCR results occurred mainly in coagulase-negative staphylococci, especially for oxacillin and rifampin. However, the specificity of mPCR was high and a positive result reliably predicted antimicrobial resistance. Including universal primers in the PCR test assay may improve the detection rate but requires additional sequencing step. TRIAL REGISTRATION: www.clinicaltrials.gov No. NCT02530229, registered at 21 August 2015 (retrospectively registered).

Improved pre-operative diagnostic accuracy for low-grade prosthetic joint infections using second-generation multiplex Polymerase chain reaction on joint fluid aspirate.

BACKGROUND: A major obstacle for the treatment of prosthetic joint infection (PJI) is the identification of the underlying causative organism. While the diagnostic criteria ruling PJI in or out have become ever more accurate, the detection of the causative pathogen(s) still relies mostly on conventional and time-consuming microbial culture. The aim of this study was to evaluate the diagnostic potential of a second-generation multiplex PCR assay (Unyvero ITI G2, Curetis AG, Holzgerlingen, Germany) used on synovial fluid specimens. Our hypothesis was that the method would yield a higher diagnostic accuracy in the pre-operative workup than synovial fluid culture. Thus, a more precise classification of septic and aseptic prosthesis failure could be achieved before revision surgery. METHODS: Prospectively collected frozen joint fluid specimens from 26 patients undergoing arthroplasty revision surgery of the hip or knee were tested as per the manufacturer's protocol. Sensitivities, specificities, positive and negative predictive values as well as positive and negative likelihood ratios with corresponding confidence intervals were estimated using the statistical software R. A combination of the serum C-reactive protein (CRP) level, leukocyte count, erythrocyte sedimentation rate, joint fluid culture, tissue biopsy culture, and tissue biopsy histology served as the gold standard. RESULTS: Of the 26 patients included in the study, 15 were infected and 11 were aseptic. Conventional joint fluid culture showed a sensitivity of 0.67 and a specificity of 0.91. Joint fluid multiplex PCR yielded a sensitivity of 0.8 and a specificity of 1.0. CONCLUSIONS: Using the second-generation Unyvero ITI cartridge on joint fluid aspirate for the detection of prosthetic joint infection, we were able to achieve a higher diagnostic accuracy than with conventional culture. We conclude that to improve pathogen detection before revision surgery, this method represents a valuable and practicable tool.

[Implant-associated joint infections]. / Implantatassoziierte Gelenkinfektionen.

Due to the increasing number of endoprosthetic joint replacement operations in older patients as well as in patients with severe primary diseases and comorbidities, the number of revision operations is continuously increasing due to infections. The infection of an endoprosthesis represents a complex clinical picture. This article provides a detailed overview of the treatment of periprosthetic infections with a focus on the diagnostic approach and treatment decision-making. A differentiation is made in periprosthetic infections between infections with a mature or immature biofilm on the surface of the implant. Depending on this, different treatment concepts are available. Highly acute infections represent an orthopedic/surgical emergency in artificial as well as in native joints. Low-grade infections play a role particularly in the area of exchange endoprosthetics. The greatest possible success is achieved only by the interplay of a timely diagnosis, sufficient surgical approach and individualized anti-infective treatment.

[Native joint infections]. / Native Gelenkinfektionen.

Joint infections are a great challenge for the treating physicians. Infection of a native joint can result in the rapid destruction of the joint if treatment is inadequate or delayed and is associated with severe life-threatening diseases, such as sepsis. This article presents a detailed overview of the treatment of joint infections of native joints with a focus on the diagnostic approach and treatment decisions. Infections in native joints are caused either endogenously by hematogenic spreading or are caused by exogenous factors. A relevant proportion of joint infections in native joints occur in connection with iatrogenic measures, such as operations, synovial punctures and joint infiltrations. Fundamentally, acute infections represent an orthopedic surgical emergency, which is associated with the necessity for immediate operative measures. The best possible success can only be achieved by an interaction between early diagnosis, an adequate surgical approach and a tailor-made anti-infectious treatment. This is also the case with periprosthetic infections, which will be dealt with in detail in a second article.

[Erratum to: Strategy for university emergency room management at the beginning of an epidemic using COVID-19 as an example]. / Erratum zu: Strategie einer universitären Notaufnahme für das COVID-19-Management im Rahmen einer beginnenden Epidemie.

[This corrects the article DOI: 10.1007/s10049-020-00759-8.].

[Strategy for university emergency room management at the beginning of an epidemic using COVID-19 as an example]. / Strategie einer universitären Notaufnahme für das COVID-19-Management im Rahmen einer beginnenden Epidemie.

Due to the increasing number of COVID-19 infections worldwide, all hospitals are faced with the challenge associated with the pandemic. In particular, emergency rooms must prepare and implement completely new workflows. This applies in particular to patient screening and selection (triage). Close cooperation with other specialist areas such as hygiene, infectiology or virology is also necessary in order to implement appropriate treatment concepts before, during and after the diagnosis is completed. In addition, communication and quality and risk management are highly relevant in addition to the clinical aspects. This article uses COVID-19 as an example to describe how emergency rooms can prepare for a pandemic.

Novel antimicrobial coatings based on polylactide for plastic biliary stents to prevent post-endoscopic retrograde cholangiography cholangitis.

BACKGROUND: Cholangitis is a common complication after endoscopic retrograde cholangiography (ERC). OBJECTIVES: To evaluate antimicrobial coatings for biliary plastic stents in relation to efficacy against biliary pathogens, drug release and toxicity. METHODS: Biliary plastic stents were prepared by coating using a polylactide drug carrier. Stent coatings contained 4% (w/w) drug content of Resomer-octenidine (RO), Resomer-octenidine and citrate (ROC), Resomer-triclosan (RT) or Resomer-gentamicin (RG). Drug-release kinetics, antimicrobial efficacies of coated biliary stents against biliary pathogens and biocompatibilities were tested. Antimicrobial efficacy measurements included MIC testing, zone of inhibition (ZOI) assays and log reduction in bacterial suspensions. RESULTS: Continuous drug release was observed in all antimicrobial stent coatings for at least 168 h with an initial peak within the first 24 h. RT-, ROC- and RG-coated stents resulted in the following log reductions in suspensions: Escherichia coli (-0.3, -7.4 and -6.6, respectively); Enterococcus faecalis (-0.05, -6.3 and -3.9, respectively); and Candida albicans (-0.04, -1.5 and -0.2, respectively). ROC had the highest log reduction in suspension and the most favourable time course of ZOI (≥2 mm, over 72 h) against all tested pathogens. Although RT coatings showed the lowest MICs, they had the lowest ZOIs after 24 h. Concerning RO, acceptable biocompatibility could only be reached by adding a citrate component. RG showed the largest ZOI after 24 h against E. coli (19.3 mm) and E. faecalis (5.1 mm), whereas the ZOI was lower against C. albicans (1.3 mm) compared with ROC (3.7 mm). CONCLUSIONS: ROC corresponds most closely to the requirements of an ideal antimicrobial stent coating to prevent post-ERC cholangitis, showing the highest log reduction in pathogen counts, the most favourable time course of ZOI and high biocompatibility.

Synovial aspiration and serological testing in two-stage revision arthroplasty for prosthetic joint infection: evaluation before reconstruction with a mean follow-up of twenty seven months.

INTRODUCTION: The two-stage revision protocol is the gold standard for controlling and treating low-grade prosthetic joint infections of total hip and total knee arthroplasty. The antibiotic pause for diagnostic reasons before reconstruction (stage two) is discussed in relation to the persistence of the infection and the development of resistant bacterial strains. Serological markers and a synovial analysis are commonly used to exclude the persistence of infection. Therefore, we asked (1) is the serological testing of C-reactive protein and leucocytes a valuable tool to predict a persistence of infection? and (2) what is the role of synovial aspiration of Plymethylmethacrylat (PMMA) spacers in hip and knee joints? MATERIALS AND METHODS: One hundred twelve patients who were MSIS criteria-positive for a prosthetic joint infection were studied, including 45 total hip arthroplasties (THA) and 67 total knee artrhoplasties (TKA) patients. All patients were treated with a two-stage-protocol using a mobile PMMA spacer after a 14-day antibiotic-free interval, during which we measured serological markers (C-reactive protein and leucocytes) and performed synovial aspiration (white blood cell count, polymorphonuclear cell percentage, and microbiological culture) in these patients and compared the results with those of their long-term-follow-up (mean follow-up 27 months, range 24-36 months). RESULTS: Of the 112 patients, 89 patients (79.5%; 95% CI 72-86.9) exhibited infection control after a two-stage exchange, and we detected most methicillin-resistant, coagulase-negative Staphylococci (CoNS) in cases of a persistent infection. The mean sensitivity of serum C-reactive protein in the patients was 0.43 (range 0.23-0.64), and the mean specificity was 0.73 (range 0.64-0.82). For serum leucocytes, the mean sensitivity was 0.09 (range 0-0.29), and the mean specificity was 0.81 (range 0.7-0.92). The mean sensitivity for the WBC count in the synovial fluid (PMMA spacer aspiration) was 0.1 (range 0-0.29), and the mean specificity was 0.79 (range 0.68-0.92). For the PMN percentage, the mean sensitivity was 0.1 (range 0-0.29), and the mean specificity was 0.79 (range 0.68-0.92). No cut-off values could be established for C-reactive protein, leucocytes, WBC count and PMN percentage due to the low AUC. CONCLUSION: No reliable markers were identified for the long-term persistence of infection. C-reactive protein and leucocytes were often elevated, even when the infection was controlled. In addition, normalized serum markers did not exclude the persistence of infection during follow-up. The synovial analysis of the WBC count and PMN percentage did not predict the persistence of infection. However, microbiological synovial fluid analysis is often misleading due to false positive microbiological cultures, which results in overtreatment.

Performance of automated multiplex PCR using sonication fluid for diagnosis of periprosthetic joint infection: a prospective cohort.

PURPOSE: Sonication of explanted prostheses improved the microbiological diagnosis of periprosthetic joint infections (PJI). We evaluated the performance of automated multiplex polymerase chain reaction (PCR) using sonication fluid for the microbiological diagnosis of PJI. METHODS: In a prospective cohort using uniform definition criteria for PJI, explanted joint prostheses were investigated by sonication and the resulting sonication fluid was analyzed by culture and multiplex PCR. McNemar's Chi-squared test was used to compare the performance of diagnostic tests. RESULTS: Among 111 patients, PJI was diagnosed in 78 (70%) and aseptic failure in 33 (30%). For the diagnosis of PJI, the sensitivity and specificity of periprosthetic tissue culture was 51 and 100%, of sonication fluid culture 58 and 100%, and of sonication fluid PCR 51 and 94%, respectively. Among 70 microorganisms, periprosthetic tissue culture grew 52 (74%), sonication fluid culture grew 50 (71%) and sonication fluid PCR detected 37 pathogens (53%). If only organisms are considered, for which primers are included in the test panel, PCR detected 37 of 58 pathogens (64%). The sonication fluid PCR missed 19 pathogens (predominantly oral streptococci and anaerobes), whereas 7 additional microorganisms were detected only by PCR (including Cutibacterium spp. and coagulase-negative staphylococci). CONCLUSIONS: The performance of multiplex PCR using sonication fluid is comparable to culture of periprosthetic tissue or sonication fluid. The advantages of PCR are short processing time (< 5 h) and fully automated procedure. However, culture technique is still needed due to the low sensitivity and the need of comprehensive susceptibility testing. Modification of primers or inclusion of additional ones may improve the performance of PCR, especially of low-virulent organisms.

[Antibiotic strategies in trauma surgery : Treatment of implant-associated infections]. / Antiinfektiöse Strategien in der Unfallchirurgie : Therapie osteosyntheseassoziierter Infektionen.

Implant-associated infections represent a serious complication following fracture management. Due to biofilm formation, an optimized treatment strategy is required to treat these infections. Interdisciplinary cooperation between trauma surgeon, infectious diseases specialist and microbiologist enables the deployment of a concerted surgical and antibiotic treatment concept, which significantly influences treatment success. Fracture healing and chronic osteomyelitis prevention are the primary treatment goals. In general, the eradication of infection is possible with surgical debridement, change or removal of the implant and adequate antibiotic therapy. In some cases, suppressive therapy until consolidation of fracture and later removal of the implant is an option.

A new model of implant-related osteomyelitis in the metaphysis of rat tibiae.

BACKGROUND: Animal models serve as an important tool to understand peri-implant infection. Most of the models use high bacterial loads (>10(4) colony forming units, CFU) to provide high infection rates. Therefore these animals evolve rather similarly, making comparison between groups and statistical analysis possible. On the other hand, to mimic clinical constellation of surgery-related infections the use of low amounts of bacteria would be more advantageous. METHODS: We developed a metaphyseal rat model of peri-implant bone infection with low amount of bacterial loads (10(2) and 10(3) CFU of Staphylococcus aureus) and investigated osseointegration of the implants coated with hydroxyapatite (HA) and low-dosed HA-silver (HA-Ag). Non-infected implants served as controls. After 6 weeks rats were sacrificed and implants evaluated for osseointegration and infection. RESULTS: Infection of implanted devices was reliably induced, independently whether 10(2) or 10(3) CFU of S. aureus were inoculated and HA or HA-Ag coated implants were used. No systemic infection was present in any of the animals at the time of sacrifice, and no animal developed acute infection requiring premature sacrifice. All CFU counts of the implant and the bone at sacrifice were significantly higher than the inoculated load (p < .05). All sterilely inserted implants showed excellent osseointegration and no infection. CONCLUSIONS: Our present study of a rat tibia model reliably induced osteomyelitis in the metaphysis with low-doses of bacteria. The addition of low-dosed Ag to the implant coating was not able to reduce the infection rates. The results demonstrate that it is possible to develop a model of implant-related osteomyelitis in rats with low amounts of bacteria to better mimic clinical constellations. No other promoters of infection besides insertion of the screw implant were used in this model.

Risk factors for increased antimicrobial resistance: a retrospective analysis of 309 acute cholangitis episodes.

OBJECTIVES: To assess the risk factors for increased antimicrobial resistance among Enterobacteriaceae representing the most common biliary pathogens. METHODS: A retrospective analysis was conducted of 276 patients with acute cholangitis treated at a German tertiary centre between April 1996 and May 2009. The resistance patterns among Enterobacteriaceae isolated from blood/bile cultures were compared and related to age, sex, the genesis of the cholangitis and the type and number of previous interventional procedures [percutaneous transhepatic cholangiography (PTC)/endoscopic retrograde cholangiography (ERC)]. Univariate and multivariate generalized estimation equation models were used to compute ORs with corresponding 95% CIs for the binomial outcomes. RESULTS: According to the univariate analysis, patients undergoing stent therapy had a smaller proportion of Enterobacteriaceae with susceptibility to quinolones (ofloxacin/ciprofloxacin) (184/239 versus 205/221; P < 0.001) and to ceftriaxone (208/239 versus 209/222; P = 0.014). Logistic regression analysis revealed that the odds for acquiring ceftriaxone-resistant Enterobacteriaceae were 4-fold higher than in patients who had not undergone stent therapy (P = 0.039). Furthermore, an increased number of interventional procedures (PTC/ERC) was associated with lower susceptibility. The odds for susceptibility to ampicillin, ampicillin/sulbactam, ceftriaxone, quinolones and co-trimoxazole decreased by 2%, 2%, 4%, 6% and 3%, respectively, per interventional procedure. Age, sex and type of interventional procedure displayed no significant relationship to the development of antimicrobial resistance. CONCLUSIONS: Stent therapy was found to be a risk factor for increased antimicrobial resistance in patients with acute cholangitis, particularly those who had undergone numerous interventional procedures prior to the onset of the cholangitis.

Does the Duration of Perioperative Antibiotic Prophylaxis Influence the Incidence of Postoperative Surgical-Site Infections in Implant-Based Breast Reconstruction in Women with Breast Cancer? A Retrospective Study.

BACKGROUND: Perioperative antibiotic prophylaxis is an established concept to reduce the risk of surgical-site infections; however, the optimal treatment duration in prosthetic breast reconstruction is still controversial. This study evaluated a potential association between the perioperative antibiotic prophylaxis duration (≤24 hours versus >24 hours) and incidence of postoperative surgical-site infections in immediate implant-based breast reconstruction in breast cancer patients. METHODS: A descriptive, retrospective analysis of surgical-site infections after immediate implant-based breast reconstruction in breast cancer patients between January of 2011 and December of 2018 was performed. The incidence of postoperative surgical-site infections in patients with more than 24 hours of perioperative antibiotic prophylaxis was compared to patients treated for 24 hours or less. RESULTS: A total of 240 patients who met criteria were included. There were no relevant epidemiologic, clinical, or histopathologic differences between groups. Surgical-site infections as defined by the Centers for Disease Control and Prevention criteria occurred in 25.8 percent. A risk factor-adjusted analysis by a prespecified multiple logistic regression model showed that 24 hours or less of perioperative antibiotic prophylaxis was not inferior to treatment for more than 24 hours. The upper limit of the one-sided 95 percent confidence interval of the risk difference was 9.4 percent (below the prespecified noninferiority margin of 10 percent leading to statistical significance). Risk factors for a surgical-site infection included obesity and postoperative wound complications. CONCLUSIONS: The study found no association between short-course perioperative antibiotic prophylaxis (≤24 hours) and an increased rate of postoperative surgical-site infection. This is of high clinical relevance because short-course treatment can help reduce side effects and the emergence of antimicrobial resistance and prevent surgical-site infections as effectively as a prolonged perioperative antibiotic prophylaxis course. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Effect of an Intensified Antibiotic Stewardship Program at an Orthopedic Surgery Department.

Background: Institutional programs such as antibiotic stewardship (ABS) programs offer possibilities to monitor and modify antibiotic usage with the aim of reducing antibiotic resistance. In orthopedic units that treat peri-prosthetic joint infections (PJIs), ABS programs are still rare, however, there is extensive use of high-risk antibiotic agents and an increased risk for the occurrence of Clostridium difficile infections (CDIs). Patients and Methods: An ABS program was implemented at the Department of Orthopedic Surgery at a university hospital. Quarterly antibiotic consumption was measured in defined daily doses (DDDs) per 100 patient-days (PDs) at 10 quarters before the intervention and seven quarters after the intervention. The effect of the new antibiotic policy on drug use rates was evaluated using an interrupted time-series analysis. Estimated changes over time in the incidence of CDIs (cases per 1,000 PDs) were analyzed. Results: A remarkable percentual reduction in second-generation cephalosporin use of 83% (p < 0.001; pre-intervention level, 81.486 DDDs/100 patient-days; post-intervention level, 13.751 DDDs/100 PDs) and clindamycin administration of 78% (p < 0.001; pre-intervention level, 18.982 DDDs/100 PDs; post-intervention level, 4.216 DDDs/100 PDs) was observed after implementation of ABS interventions. Total antibiotic use declined by 25% (p < 0.001; pre-intervention level, 129.078 DDDs/100 PDs; post-intervention level, 96.826 DDDs/100 PDs). Conclusions: This research assessed the positive impact of an intensified ABS program at an orthopedic department specializing in PJIs. Antibiotic stewardship program interventions encourage the reduction of total antibiotic usage and especially high-risk antibiotic agents, associated with the development of antimicrobial resistance.

Diagnostic accuracy of multiplex polymerase chain reaction on tissue biopsies in periprosthetic joint infections.

The diagnosis and treatment of periprosthetic joint infection (PJI) currently relies on cultures, which are time-consuming and often fail. Multiplex PCR assays promise reliable and prompt results, but have been heterogeneously evaluated. In this study, we analyse multiplex PCR in pathogen identification using only tissue biopsies. 42 patients after revision arthroplasty of the hip or knee were evaluated using multiplex PCR to identify microorganisms. The patients were classified according to the diagnostic criteria published by Zimmerli et al. and the results were compared to the respective microbiological cultures. PJI was detected in 15 patients and 27 revisions were aseptic. The multiplex PCR of tissue biopsies had a sensitivity of 0.3 (95% CI 0.12-0.62), a specificity of 1.0 (0.87-1.0), a positive predictive value of 1.0 (0.48-1.0) and a negative predictive value of 0.73 (0.56-0.86). The diagnostic accuracy of multiplex PCR on tissue biopsy samples is low in comparison to routine microbiological cultures. The evaluation of tissue biopsies using multiplex PCR was prone to false negative results. However, multiplex PCR assays have the advantage of rapid pathogen identification. We therefore recommend further investigation of multiplex PCR in the setting of suspected PJI with a careful choice of specimens.

Dexamethasone therapy and rates of secondary pulmonary and bloodstream infections in critically ill COVID-19 patients.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has become a pandemic. Bacterial superinfections seem to be associated with higher mortality in COVID-19 patients in intensive care units (ICUs). However, details on the prevalence and species distribution of secondary infections are limited. Moreover, the increasing use of dexamethasone may pose an additional risk of superinfections. METHODS: We performed a single-center retrospective study of the clinical and microbiological characteristics of 154 COVID-19 patients admitted to the ICU between March 2020 and January 2021, focusing on bacterial infections, use of antimicrobial agents and dexamethasone therapy. RESULTS: The median age was 68 years; 67.5% of the patients were men. Critically ill COVID-19 patients were treated with dexamethasone since July 2020 (second wave), which was not common during the first wave of the pandemic. In the dexamethasone group (n=90, 58.4%), respiratory pathogens were detected more frequently, as were multidrugresistant pathogens. The number of patients with polymicrobial detection of respiratory pathogens was significantly increased (p=0.013). The most frequently detected species were Enterobacterales, Staphylococcus aureus, and Aspergillus fumigatus. The rates of bloodstream infections did not differ between the groups. The use of dexamethasone in ICU COVID-19 patients was associated with higher rates of respiratory infectious complications. CONCLUSIONS: Secondary infections are present in a substantial fraction of critically ill COVID-19 patients. Respiratory pathogens were detectable in the majority of COVID-19 ICU patients. The use of dexamethasone poses a potential risk of secondary pulmonary infections. Infectious complications in patients with dexamethasone therapy could be associated with worse outcomes.