Shotgun sequencing of sonication fluid for the diagnosis of orthopaedic implant-associated infections with Cutibacterium acnes as suspected causative agent.

Orthopaedic implant-associated infections (OIAIs) due to Cutibacterium acnes can be difficult to diagnose. The aim of this pilot study was to determine if metagenomic next-generation sequencing (mNGS) can provide additional information to improve the diagnosis of C. acnes OIAIs. mNGS was performed on sonication fluid (SF) specimens derived from 24 implants. These were divided into three groups, based on culture results: group I, culture-negative (n = 4); group II, culture-positive for C. acnes (n = 10); and group III, culture-positive for other bacteria (n = 10). In group I, sequence reads from C. acnes were detected in only one SF sample, originating from a suspected case of OIAIs, which was SF and tissue culture-negative. In group II, C. acnes sequences were detected in 7/10 samples. In group III, C. acnes sequence reads were found in 5/10 samples, in addition to sequence reads that matched the bacterial species identified by culture. These samples could represent polymicrobial infections that were missed by culture. Taken together, mNGS was able to detect C. acnes DNA in more samples compared to culture and could be used to identify cases of suspected C. acnes OIAIs, in particular regarding possible polymicrobial infections, where the growth of C. acnes might be compromised due to a fast-growing bacterial species. However, since SF specimens are usually low-biomass samples, mNGS is prone to DNA contamination, possibly introduced during DNA extraction or sequencing procedures. Thus, it is advisable to set a sequence read count threshold, taking into account project- and NGS-specific criteria.

Nine different carbapenemase-producing organisms in a Ukrainian war-injured patient.

This is a case report of a Ukrainian war-injured patient who was colonised/infected with nine different carbapenemase-producing organisms (CPO). The patient was initially treated in Ukraine. After two months he was admitted to a Danish hospital where he underwent extensive surgery and received broad-spectrum antibiotics. In screening and clinical samples, nine different CPO were cultured which in combination were untreatable with antibiotics. To our knowledge, this is the first patient in Denmark with such a high number of different CPO. This may be a sign that we are entering a postantibiotic era.

ESSKA and EBJIS recommendations for the management of infections after anterior cruciate ligament reconstruction (ACL-R): prevention, surgical treatment and rehabilitation.

PURPOSE: Infection after anterior cruciate ligament reconstruction (ACL-R) is a rare but severe complication. Despite an increase in articles published on this topic over the last decade, solid data to optimized diagnostic and therapeutic measures are scarce. For this reason, the European Bone and Joint Infection Society (EBJIS) and the European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) collaborated in order to develop recommendations for the diagnosis and management of infections after ACL-R. The aim of the workgroup was to perform a review of the literature and provide practical guidance to healthcare professionals involved in the management of infections after ACL-R. METHODS: An international workgroup was recruited to provide recommendations for predefined clinical dilemmas regarding the management of infections after ACL-R. MEDLINE, EMBASE, Cochrane Library and Scopus databases were searched for evidence to support the recommended answers to each dilemma. RESULTS: The recommendations were divided into two articles. The first covers etiology, prevention, diagnosis and antimicrobial treatment of septic arthritis following ACL-R and is primarily aimed at infectious disease specialists. This article includes the second part of the recommendations and covers prevention of infections after ACL-R, surgical treatment of septic arthritis following ACL-R and subsequent postoperative rehabilitation. It is aimed not only at orthopedic surgeons, but at all healthcare professionals dealing with patients suffering from infections after ACL-R. CONCLUSION: These recommendations guide clinicians in achieving timely and accurate diagnosis as well as providing optimal management, both of which are paramount to prevent loss of function and other devastating sequelae of infection in the knee joint. LEVEL OF EVIDENCE: V.

Recommendations on diagnosis and antimicrobial treatment of infections after anterior cruciate ligament reconstruction (ACL-R) endorsed by ESSKA and EBJIS.

Infection after anterior cruciate ligament reconstruction (ACL-R) is a rare but devastating complication affecting predominantly young and sportive individuals. A timely and correct diagnosis as well as optimized management is paramount to circumvent serious sequelae and compromise in life quality. These recommendations are primarily intended for use by infectious disease specialists and microbiologists, but also orthopedic surgeons and other healthcare professionals who care for patients with infections after ACL-R. They are based on evidence mainly originating from observational studies and opinions of experts in the field, and cover the management of infections after ACL-R with a special focus on etiology, diagnosis, antimicrobial treatment and prevention. Comprehensive recommendations on surgical treatment and rehabilitation are presented separately in a document primarily addressing orthopedic professionals.

Guideline for management of septic arthritis in native joints (SANJO).

This clinical guideline is intended for use by orthopedic surgeons and physicians who care for patients with possible or documented septic arthritis of a native joint (SANJO). It includes evidence and opinion-based recommendations for the diagnosis and management of patients with SANJO.

[Fracture-related infections].

Fracture-related infections (FRI) is a challenging complication with a high risk of devastation outcomes for the patients. Diagnosing FRI is often difficult, and treatment frequently requires the effort of a multidisciplinary team. Recently, an international consensus group of experts from various scientific and medical organisations has published standardised guidelines of diagnosis and treatment. This review provides a summary of the latest studies and the general principles with respect to diagnosis, treatment and aftercare of patients with FRI.

Amplicon-Based Next-Generation Sequencing as a Diagnostic Tool for the Detection of Phylotypes of Cutibacterium acnes in Orthopedic Implant-Associated Infections.

The diagnosis of orthopedic implant-associated infections (OIAIs) caused by the slow-growing anaerobic bacterium Cutibacterium acnes is challenging. The mild clinical presentations of this low-virulent bacterium along with its ubiquitous presence on human skin and human-dominated environments often make it difficult to differentiate true infection from contamination. Previous studies have applied C. acnes phylotyping as a potential avenue to distinguish contamination from infection; several studies reported a prevalence of phylotypes IB [corresponding to type H in the single-locus sequence typing (SLST) scheme] and II (SLST type K) in OIAIs, while a few others found phylotype IA1 (more specifically SLST type A) to be abundant. However, phylotype determination has mainly been done in a culture-dependent manner on randomly selected C. acnes isolates. Here, we used a culture-independent amplicon-based next-generation sequencing (aNGS) approach to determine the presence and relative abundances of C. acnes phylotypes in clinical OIAI specimens. As amplicon, the SLST target was used, a genomic fragment that is present in all C. acnes strains known to date. The aNGS approach was applied to 30 sonication fluid (SF) samples obtained from implants removed during revision surgeries, including 17 C. acnes culture-positive and 13 culture-negative SF specimens. In 53% of the culture-positive samples, SLST types were identified: relative abundances were highest for K-type C. acnes, followed by H- and D-type C. acnes. Other types, including A- and C-type C. acnes that are more prevalent on human skin, had low relative abundances. The aNGS results were compared with, and confirmed by a culture-dependent approach, which included the isolation, whole genome sequencing (WGS) and phylotyping of 36 strains of C. acnes obtained from these SF samples. Besides serving as a powerful adjunct to identify C. acnes phylotypes, the aNGS approach could also distinguish mono- from heterotypic infections, i.e., infections caused by more than one phylotype of C. acnes: in eight out of nine culture-positive SF samples multiple C. acnes types were detected. We propose that the aNGS approach, along with the patient's clinical information, tissue and SF cultures and WGS, could help differentiate C. acnes contamination from true infection.

Microbiological diagnosis in cardiac implantable electronic device infections detected by sonication and next-generation sequencing.

BACKGROUND: Device-related infection (DRI) is a severe complication of treatment with cardiac implantable electronic devices. Identification of the causative pathogen is essential for optimal treatment, but conventional methods often are inadequate. OBJECTIVE: The purpose of this study was to improve microbiological diagnosis in DRI using sonication and next-generation sequencing analysis. The primary objective was identification of causative pathogens. The secondary objective was estimation of the sensitivity of different microbiological methods in detecting the causative pathogen. METHODS: Consecutive patients with clinical signs of DRI between October 2016 and January 2019 from 3 tertiary centers in Denmark were included in the study. Patients underwent a diagnostic approach, including blood cultures and perioperative collection of microbiological samples (pocket swab, pocket tissue biopsies, generator, and leads). Conventional culturing was performed, and device components were sonicated and examined with an amplicon-based metagenomic analysis using next-generation sequencing. The results were compared with a reference standard-identified causative pathogen. RESULTS: In 110 patients with clinical signs of pocket (n = 50) or systemic DRI (n = 60), we collected 109 pocket swabs, 220 pocket tissue biopsies, 106 generators, 235 leads, and a minimum 1 set of blood cultures from 102 patients. Combining all findings, we identified the causative pathogen in 95% of cases, irrespective of DRI type. The usability of each microbiological method differed between DRI types. In pocket DRI, next-generation sequencing analysis of generators achieved sensitivity of 90%. For systemic DRI, blood cultures reached sensitivity of 93%. CONCLUSION: Using a strategy including sonication and next-generation sequencing, we identified the causative pathogen in 95% of DRI. Sensitivity of microbiological methods differed according to the type of DRI.

The use of negative pressure wound therapy for fracture-related infections following internal osteosynthesis of the extremity: A systematic review.

This study aimed to systematically review the current literature on studies using negative pressure wound therapy (NPWT) or dressings following fracture-related infection (FRI) in internal osteosynthesis of the extremity. Articles were analyzed on fracture and wound healing and included when comparing or describing the use of either NPWT or dressings in FRI. We conducted a systematic literature search in four electronic databases: Embase, Medline, the Cochrane Library, and Scopus. The studies were screened by two authors using Covidence.org and evaluated for risk of bias. A total of 8576 records were identified. No articles compared NPWT to dressings. Seven case reports and three case series included a total of 115 patients treated for FRI. Fracture healing was achieved in 21 out of 67 patients treated with NPWT (4 amputations and 46 not described) and all 48 patients in the dressing group (4 patients needed additional sequestrectomy procedures). Five studies did not describe fracture healing. In 57 out of 67 patients treated with NPWT, the wounds were described as healed, closed, or requiring soft tissue reconstruction (4 amputations and six lacking description). The dressing group had complete wound coverage in 18 patients and partial coverage in 30 patients. Studies were generally at high risk of bias because of insufficient descriptions of both patient demographics and outcomes. No studies compared NPWT to dressings, and the existing literature is at high risk of bias. The included studies were of low-level evidence. NPWT can be neither recommended nor advised against to cover infected osteosynthesis.

Diagnosis of orthopaedic-implant-associated infections caused by slow-growing Gram-positive anaerobic bacteria - a clinical perspective.

Slow-growing Gram-positive anaerobic bacteria (SGAB) such as Cutibacterium acnes are increasingly recognized as causative agents of implant-associated infections (IAIs) in orthopaedic surgeries. SGAB IAIs are difficult to diagnose because of their non-specific clinical and laboratory findings as well as the fastidious growth conditions required by these bacteria. A high degree of clinical suspicion and awareness of the various available diagnostic methods is therefore important. This review gives an overview of the current knowledge regarding SGAB IAI, providing details about clinical features and available diagnostic methodologies. In recent years, new methods for the diagnosis of IAI were developed, but there is limited knowledge about their usefulness in SGAB IAI. Further studies are required to determine the ideal diagnostic methodology to identify these infections so that they are not overlooked and mistakenly classified as aseptic failure.

Mycoplasma hominis septic arthritis in a patient with hypogammaglobinaemia and rheumatoid arthritis.

We describe the case of Mycoplasma hominis septic arthritis in a 58-year-old woman with a history of rheumatoid arthritis and ulcerative colitis on immunosuppressive therapy with rituximab. Treatment with anti-CD20 antibodies (eg, rituximab) leads to an immediate depletion of B cells and hence risk of reductions in immunoglobulins and increased risk of infections. This effect may last long after drug cessation. M. hominis is commensal to the genitourinary tract in sexually active adults. Extragenital M. hominis infections including septic arthritis are rare, but hypogammaglobulinaemia is a predisposing factor. As M. hominis requires extended culture, special media or PCR analysis, it is not tested routinely, which in many cases delays diagnosis and correct treatment. In our case, a diagnosis of M. hominis septic arthritis was made after 9 weeks by PCR analysis and culture of joint fluid. The patient responded well to an 8-week treatment course of moxifloxacin and doxycycline.

Microcalorimetric detection of staphylococcal biofilm growth on various prosthetic biomaterials after exposure to daptomycin.

Primary aim of this in vitro study was to test the efficacy of daptomycin to eradicate staphylococcal biofilms on various orthopedic implant materials. Secondary aim was to quantitatively estimate the formation of staphylococcal biofilm. We tested six clinically important biomaterials: Cobalt chrome, pure titanium, grid-blasted titanium, porous plasma-coated titanium with/without hydroxyapatite, and polyethylene. Biofilms of S. aureus and S. epidermidis were formed on the samples and thereafter exposed to daptomycin. Samples were subsequently sonicated in order to detect dislodged biofilm bacteria and transferred to a microcalorimeter for real-time measurement of growth-related heat flow. Minimal biofilm eradication concentration (MBEC) was determined as the lowest concentration of daptomycin required to eradicate biofilm bacteria on the sample. Median MBEC of S. aureus biofilm on smooth metallic surfaces was lower than the rough metallic surfaces. In experiments with S. epidermidis, no pattern was seen in relation to the surface roughness. Regarding the quantitative estimation of staphylococcal biofilm formation on the sample, we found a significantly higher amount of biofilm growth on the rough surfaces than the smooth samples and polyethylene. In conclusion, the presented study showed that daptomycin could eradicate S. aureus biofilm at lower concentrations on the smooth surfaces compared to the rough surfaces, as well as polyethylene. In experiments with daptomycin against S. epidermidis biofilms, no pattern was seen in relation to the surface roughness. Furthermore, we demonstrated a faster detection of staphylococcal heat flow due to higher biofilm quantity on the rough surfaces compared to smooth samples and polyethylene. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2809-2816, 2018.

Reduced ability to detect surface-related biofilm bacteria after antibiotic exposure under in vitro conditions.

Background and purpose - Antibiotic treatment of patients before specimen collection reduces the ability to detect organisms by culture. We investigated the suppressive effect of antibiotics on the growth of non-adherent, planktonic, and surface-related biofilm bacteria in vitro by using sonication and microcalorimetry methods. Patients and methods - Biofilms of Staphylococcus aureus, S. epidermidis, Escherichia coli, and Propionibacterium acnes were formed on porous glass beads and exposed for 24 h to antibiotic concentrations from 1 to 1,024 times the minimal inhibitory concentration (MIC) of vancomycin, daptomycin, rifampin, flucloxacillin, or ciprofloxacin. The beads were then sonicated to dislodge biofilm, followed by culture and measurement of growth-related heat flow by microcalorimetry of the resulting sonication fluid. Results - Vancomycin did not inhibit the heat flow of staphylococci and P. acnes at concentrations ≤1,024 µg/mL, whereas flucloxacillin at >128 µg/mL inhibited S. aureus. Daptomycin inhibited heat flow of S. aureus, S. epidermidis, and P. acnes at lower concentrations (32-128 times MIC, p < 0.001). Rifampin showed inconsistent results in staphylococci due to random emergence of resistance, which was observed at concentrations ≤1,024 times MIC (i.e. 8 µg/mL). Ciprofloxacin inhibited heat flow of E. coli at ≥4 times MIC (i.e. ≥ 0.06 µg/mL). Interpretation - Whereas time-dependent antibiotics (i.e. vancomycin and flucloxacillin) showed only weak growth suppression, concentration-dependent drugs (i.e. daptomycin and ciprofloxacin) had a strong suppressive effect on bacterial growth and reduced the ability to detect planktonic and biofilm bacteria. Exposure to rifampin rapidly caused emergence of resistance. Our findings indicate that preoperative administration of antibiotics may have heterogeneous effects on the ability to detect biofilm bacteria.