Adaptive evolution of carbapenem-resistant hypervirulent Klebsiella pneumoniae in the urinary tract of a single patient.

The emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) is a growing concern due to its high mortality and limited treatment options. Although hypermucoviscosity is crucial for CR-hvKp infection, the role of changes in bacterial mucoviscosity in the host colonization and persistence of CR-hvKp is not clearly defined. Herein, we observed a phenotypic switch of CR-hvKp from a hypermucoviscous to a hypomucoviscous state in a patient with scrotal abscess and urinary tract infection (UTI). This switch was attributed to decreased expression of rmpADC, the regulator of mucoid phenotype, caused by deletion of the upstream insertion sequence ISKpn26. Postswitching, the hypomucoid variant showed a 9.0-fold decrease in mice sepsis mortality, a >170.0-fold reduction in the ability to evade macrophage phagocytosis in vitro, and an 11.2- to 40.9-fold drop in growth rate in normal mouse serum. Conversely, it exhibited an increased residence time in the mouse urinary tract (21 vs. 6 d), as well as a 216.4-fold boost in adhesion to bladder epithelial cells and a 48.7% enhancement in biofilm production. Notably, the CR-hvKp mucoid switch was reproduced in an antibiotic-free mouse UTI model. The in vivo generation of hypomucoid variants was primarily associated with defective or low expression of rmpADC or capsule synthesis gene wcaJ, mediated by ISKpn26 insertion/deletion or base-pair insertion. The spontaneous hypomucoid variants also outcompeted hypermucoid bacteria in the mouse urinary tract. Collectively, the ISKpn26-associated mucoid switch in CR-hvKp signifies the antibiotic-independent host adaptive evolution, providing insights into the role of mucoid switch in the persistence of CR-hvKp.

Impact of LuxS on virulence and pathogenicity in Klebsiella pneumoniae exhibiting varied mucoid phenotypes.

How the LuxS/AI-2 quorum sensing (QS) system influences the pathogenicity of K. pneumoniae is complicated by the heterogeneity of the bacterial mucoid phenotypes. This study aims to explore the LuxS-mediated regulation of the pathogenicity of K. pneumoniae with diverse mucoid phenotypes, including hypermucoid, regular-mucoid, and nonmucoid. The wild-type, luxS knockout, and complemented strains of three K. pneumoniae clinical isolates with distinct mucoid phenotypes were constructed. The results revealed the downregulation of virulence genes of regular-mucoid, and nonmucoid but not hypermucoid strains. The deletion of luxS reduced the pathogenicity of the regular-mucoid, and nonmucoid strains in mice; while in hypermucoid strain, luxS knockout reduced virulence in late growth but enhanced virulence in the early growth phase. Furthermore, the absence of luxS led the regular-mucoid and nonmucoid strains to be more sensitive to the host cell defense, and less biofilm-productive than the wild-type at both the low and high-density growth state. Nevertheless, luxS knockout enhanced the resistances to adhesion and phagocytosis by macrophage as well as serum-killing, of hypermucoid K. pneumoniae at its early low-density growth state, while it was opposite to those in its late high-density growth phase. Collectively, our results suggested that LuxS plays a crucial role in the pathogenicity of K. pneumoniae, and it is highly relevant to the mucoid phenotypes and growth phases of the strains. LuxS probably depresses the capsule in the early low-density phase and promotes the capsule, biofilm, and pathogenicity during the late high-density phase, but inhibits lipopolysaccharide throughout the growth phase, in K. pneumoniae.IMPORTANCECharacterizing the regulation of physiological functions by the LuxS/AI-2 quorum sensing (QS) system in Klebsiella pneumoniae strains will improve our understanding of this important pathogen. The genetic heterogeneity of K. pneumoniae isolates complicates our understanding of its pathogenicity, and the association of LuxS with bacterial pathogenicity has remained poorly addressed in K. pneumoniae. Our results demonstrated strain and growth phase-dependent variation in the contributions of LuxS to the virulence and pathogenicity of K. pneumoniae. Our findings provide new insights into the important contribution of the LuxS/AI-2 QS system to the networks that regulate the pathogenicity of K. pneumoniae. Our study will facilitate our understanding of the regulatory mechanisms of LuxS/AI-2 QS on the pathogenicity of K. pneumoniae under the background of their genetic heterogeneity and help develop new strategies for diminished bacterial virulence within the clinical K. pneumoniae population.

Clinical, phenotypic characterization and genomic analysis of the mucoid Acinetobacter baumannii from a teaching hospital.

BACKGROUND: Acinetobacter baumannii (A. baumannii) has become a significant nosocomial pathogen globally over the past decade due to the increasing prevalence of antibiotic-resistant isolates. The formation of the mucoid phenotype is a crucial adaptive defense response to external pressure, but the clinical, phenotypic and genotypic characteristics and their relationship with sequence types (ST) and K locus (KL) types remain unclear. METHODS: In this study, we screened a total of 736 A. baumannii isolates, from which we identified and characterized 13 mucoid isolates. The study explored the clinical characteristics of patients with mucoid isolates, investigated the mucoid phenotype, performed capsule observation, quantified capsule production, and assessed antimicrobial susceptibility. Subsequently, whole-genome sequencing (WGS) was used to analyze the sequence types (ST), loci for capsular polysaccharide (KL), antibiotic resistance genes, virulence genes, and core-genome single-nucleotide polymorphisms (SNPs). Additionally, the virulence of all mucoid strains was evaluated through serum resistance assay, biofilm-forming assay, and Galleria mellonella survival assay. RESULTS: All mucoid A. baumannii isolates were found to be encapsulated and extremely drug-resistant. Among patients infected with these isolates, 92.3 % had pulmonary infections, and the 30-day mortality rate was 61.5 %. The analysis revealed that not all strains are highly virulent. Whole-genome sequencing (WGS) identified the sequence types as ST136, ST208, ST381, ST195, and ST281, and the capsular types as KL77, KL7, KL33, KL2, and KL3. The ST208 and KL7 isolates exhibited higher virulence and greater biofilm formation, with KL7 isolates also showing higher capsule production. Despite these differences, no significant variations in virulence genes were observed among the mucoid isolates, except for biofilm-associated and quorum-sensing genes. The highly virulent ST208/KL7 strains (AB276, AB313, and AB552) lacked biofilm-associated genes (csuA/BABCDE), indicating these genes do not directly cause differences in biofilm formation. CONCLUSION: The mucoid A. baumannii isolates were extensively drug-resistant, and infections caused by these isolates could lead to higher mortality. However, not all strains had high virulence, with variations likely related to specific sequence types (ST) and K locus (KL) types.

Patellar height: an important parameter in knee MRI associated with tendinopathy, quadriceps fat pad edema (QFPE), anterior cruciate ligament mucoid degeneration (ACL-MD), and lateral cartilage damage.

BACKGROUND: Some pathologies associated with abnormal patellar height have been reported in the literature. However, its relationship with some pathologies, such as anterior cruciate ligament mucoid degeneration (ACL-MD) and focal cartilage defect, has not been investigated. PURPOSE: To investigate the relationship between patellar height with patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and focal cartilage defect. MATERIAL AND METHODS: Magnetic resonance imaging of the knees of 261 patients were classified into three groups as normal, patella alta, and patella baja, and evaluated in terms of patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and focal cartilage defect. RESULTS: There were 261 patients (140 men, 121 women; age range = 18-60 years; mean age = 30 ± 4.7 years). Of the 261 patients, 181 (69.3%) were normal, 56 (21.4%) were patella alta, and 24 were patella baja (9.1%). Patellar-quadriceps tendinopathy, quadriceps fat pad edema, and ACL-MD rates were significantly higher compared to the normal group (P <0.05). While a moderate positive correlation was found between patellar height shift and patellar-quadriceps tendinopathy and ACL-MD, there was a small correlation between patellar height shift and quadriceps fat pad edema. The rate of focal cartilage defect was significantly higher in the middle part of the lateral femoral condyle and lateral knee joint only in patella alta. CONCLUSION: The risk of patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and lateral focal cartilage defect is higher in patients with alta-baja. The radiologist should evaluate these pathologies more carefully, especially subtle ones, in patients with abnormal patellar height.

Association of tibial slope alterations with anterior cruciate ligament (ACL) injury and mucoid degeneration.

OBJECTIVE: To compare radiographic measurements of lateral tibial slope (LTS), medial TS (MTS), and coronal TS (CTS) in MRI-defined intact, injured, and mucoid-degenerated native ACL knees and determine inter-reader reliability. MATERIALS AND METHODS: Patient records from 2 years at tertiary care hospitals were reviewed for individuals aged 18-100 undergoing 3-Tesla knee MRI and radiographs. Two randomly selected cohorts, control, and pathologic ACLs on MRI with 86 patients each, were age, gender, and BMI-matched. A fellowship-trained musculoskeletal radiologist reevaluated curated images, characterizing ACL status. Two trained medical students independently collected clinical data and measured slopes on blinded radiographs. ICC, Cohen's kappa, and case-control matching were performed using SPSS statistical package, with ICC and ANOVA used for comparisons. RESULTS: Among 172 patients with 172 MRIs and radiographs, there were 86 controls and 86 ACL lesions. There were 108/172 (62.79%) males and 64/172 (37.21%) females. ICCs were 0.966 for MTS, 0.975 for LTS, and 0.978 for CTS. Mucoid degeneration patients had a higher BMI and were older than control (p < .05) or completely torn (p < .001) ACL patients. There was no difference in TS between normal and pathologic ACLs; however, LTS-MTS differences were larger with partial tears (2.5 ± 4.9) than normal ACLs by 4.5° (± 1.2, p < .001), complete tears by 4.5° (± 1.3, p < .001), and mucoid degeneration by 4.9° (± 1.5, p = .001). CONCLUSION: Various TS measurements are reliable. LTS-MTS differences are associated with different ACL lesions compared to normal ACLs.

Predicting anterior cruciate ligament degeneration using magnetic resonance imaging: Insights from histological evaluation.

BACKGROUND: Mucoid degeneration of the anterior cruciate ligament is a pathological condition that may impair knee mechanics and contribute to the symptomatology of osteoarthritis. This study aimed to evaluate whether preoperative magnetic resonance imaging can predict anterior cruciate ligament degeneration, specifically mucoid degeneration, and to elucidate the histopathological characteristics of mucoid degeneration in knee osteoarthritis patients. METHODS: We evaluated a total of 95 knees of osteoarthritis patients (23 males, 72 females; mean age: 72.7 ± 7.5) scheduled for total knee arthroplasty. The relationship between preoperative magnetic resonance imaging findings and the histopathological evidence of anterior cruciate ligament mucoid degeneration was examined. Immunohistochemical analysis was employed for collagen types (COL-I, COL-II), chondrogenesis (SOX9), and vascularity (CD31). RESULTS: High signal intensity on magnetic resonance imaging showed a positive correlation with Alcian Blue staining areas (rs = 0.59, p < 0.01) and the swelling index (rs = 0.62, p < 0.01), indicating advanced mucoid degeneration. The absence of synovial lining around the anterior cruciate ligament was associated with more severe degeneration. In the histological evaluations, advanced degeneration was characterized by an increase in chondroid metaplasia and collagen disorientation. The Alcian Blue and SOX9 correlation was positive (rs = 0.69, p < 0.01), but negative with COL-I (rs = -0.38, p = 0.03) and vascularity (CD31) (rs = -0.60, p < 0.01). CONCLUSIONS: Preoperative magnetic resonance imaging is an effective tool in assessing the severity of anterior cruciate ligament degeneration; it influences surgical decisions. High signal intensity on magnetic resonance images denotes advanced mucoid degeneration. The absence of synovial lining around the anterior cruciate ligament is associated with more severe degeneration and may accelerate degenerative changes. Chondroid metaplasia and collagen disorientation mark advanced degeneration. Magnetic resonance imaging can be used to gauge the degree of anterior cruciate ligament degeneration in osteoarthritis.

Isolated arterial mucoid intimal thickening lesion in early post-transplant kidney allograft biopsies.

INTRODUCTION: Thrombotic microangiopathy (TMA) on kidney biopsy shows a variable combination of features: arterial mucoid intimal thickening, acellular closure of glomerular capillary loops, fragmented red blood cells, fibrin thrombi, and arterial fibrinoid necrosis. However, some early post-transplant kidney biopsies show only arterial mucoid intimal thickening. We aimed to elucidate the importance of this finding. METHODS: We identified 19 biopsies showing isolated arterial mucoid intimal thickening and compared them with 22 bona fide TMA biopsies identified based on the pathological findings (excluding rejection) (2011-2020). Additionally, delayed graft function (DGF) (n = 237), and no DGF (control, n = 1314) groups were included for survival analysis. RESULTS: Seven of 19 cases with isolated arterial mucoid intimal thickening showed peripheral blood schistocytes but no other systemic features of TMA. Eight patients underwent adjustments in maintenance immunosuppression (mainly calcineurin inhibitors). None of the cases progressed to full-blown TMA on consecutive biopsies. The overall and death-censored graft survival rates in this group were comparable to the DGF group, but significantly better than the TMA group (P = .005 and .04, respectively). CONCLUSIONS: Isolated arterial mucoid intimal thickening in early post-transplant biopsies may be an early/mild form of TMA, probably requiring adjustment in immunosuppressive regimen. Careful exclusion of known causes of TMA, and donor-derived arterial injury are important.

Ancillary findings in distinguishing between anterior cruciate ligament mucoid degeneration and sprain on MRI: a practical approach.

BACKGROUND: Imaging findings of both anterior cruciate ligament (ACL) sprain and mucoid degeneration overlap in some cases, which may cause errors in magnetic resonance imaging (MRI) evaluation. PURPOSE: To determine the ancillary findings on MRI in distinguishing between ACL sprain and mucoid degeneration, and also to obtain a diagnostic scheme. MATERIAL AND METHODS: MRI scans of 77 patients with ACL mucoid degeneration and 77 cases with ACL sprain were retrospectively evaluated to compare with regard to parameters of age, sex, side, the status of posterior cruciate ligament - medial collateral ligament - lateral collateral ligament, bone marrow edema, intraosseous cyst, subchondral sclerosis, chondromalacia, meniscus tear, effusion, and osteochondral body. A decision tree algorithm was created to predict pathology in ACL, whether it was a sprain or mucoid degeneration. RESULTS: The prevalence of female sex, femoral intraosseous cyst, tibial intraosseous cyst, subchondral sclerosis, femoral chondromalacia, tibial chondromalacia, medial meniscus tear, and lateral meniscus tear were significantly higher in the ACL mucoid degeneration group (P < 0.001, P = 0.016, P < 0.001, P = 0.003, P < 0.001, P < 0.001, P < 0.001, and P < 0.001, respectively). The probability of being mucoid degeneration increased 41.2 times (95% confidence interval [CI] = 5.296-321.132) in cases with tibial intraosseous cyst and increased 1.05 times (95% CI = 1.010-1.080) with each one-year increase in age (P < 0.001 and P = 0.011, respectively). The decision tree algorithm had an overall accuracy of 79.2%. CONCLUSION: Ancillary findings are helpful in the diagnosis of suspicious cases for ACL mucoid degeneration and ACL sprain. The decision tree algorithm offers a practical and successful approach to this issue.

Posterior tibial slope, notch width index and tibial tubercle to trochlear groove distance contribute to development of mucoid degeneration of the anterior cruciate ligament: a systematic review.

PURPOSE: To determine what knee morphological factors are associated with the development of mucoid degeneration of the anterior cruciate ligament (ACL). METHODS: Three databases MEDLINE, PubMed and EMBASE were searched from inception to January 29th, 2023 for literature outlining knee morphological factors that potentially lead to the development of mucoid degeneration of the ACL. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on receiver operating characteristic (ROC) curve parameters such as area under the curve (AUC), sensitivity and specificity, odds ratios, as well as p values for comparisons of values between mucoid degeneration of the ACL and control patients were recorded. The Methodological Index for Non-Randomized Studies (MINORS) score was used for all studies to perform a quality assessment of included studies. RESULTS: A total of 7 studies comprising 1326 patients (1330 knees) were included in this review. Four studies reported a significant association between increasing posterior tibial slope angles and mucoid degeneration of the ACL presence, with one study specifying that posterolateral tibial slope had a greater association than posteromedial tibial slope. Two studies reported a significant association between lower notch width index values and mucoid degeneration of the ACL presence. One study found that the presence of trochlear dysplasia was correlated with mucoid degeneration of the ACL and two studies found that increased tibial tuberosity-trochlear groove distance (TT-TG) was associated with mucoid degeneration of the ACL. CONCLUSION: Increased posterior tibial slope, decreased notch width index, and elevated TT-TG and trochlear dysplasia were associated with the presence of mucoid degeneration of the ACL. Information from this review can aid surgeons in understanding what morphological features predispose their patients to the development of mucoid degeneration of the ACL. Identifying what features predispose patients to mucoid degeneration of the ACL can help determine if regular screening or preventative strategies are necessary. LEVEL OF EVIDENCE: Level III.

Partial debridement is the most commonly reported treatment option for mucoid degeneration of the anterior cruciate ligament: a systematic review.

PURPOSE: To determine clinical outcomes and risks of various management strategies for mucoid degeneration of the anterior cruciate ligament (MD-ACL). METHODS: Three databases MEDLINE, PubMed and EMBASE were searched from inception to January 29th, 2023 for literature outlining clinical outcomes for various management strategies of MD-ACL. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on satisfaction scores, visual analogue scale (VAS) scores, Lysholm scores, International Knee Documentation Committee (IKDC) scores, Knee Osteoarthritis and Outcome Scores (KOOS), range of motion and Lachman test were recorded. RESULTS: A total of 14 studies comprising 776 patients (782 knees) were included in this review. Partial debridement was reported in ten (71.4%) studies comprising 446 patients, showing significant improvements in VAS, Lysholm, IKDC scores and range of motion. Complete debridement was reported by two (14.2%) studies comprising 250 patients, and resulted in increases in Lysholm scores, KOOS, and range of motion. Reduction plasty was reported in two (14.2%) studies comprising 26 patients and showed improvements in VAS and Lysholm scores, and range of motion. Other methods of treatment included conservative management and ultrasound decompression. Complete debridement resulted in 10/23 (43%) patients with a positive Lachman test. This was followed by reduction plasty and partial debridement, with 5/26 (19.2%) and 45/340 (13.2%) patients respectively having positive Lachman or elevated knee arthrometer scores. Pivot shifting was only reported in studies on partial debridement and reduction plasty, with 14/93 (15.1%) and 1/21 (4.8%) patients have positive results, respectively. CONCLUSION: The most commonly reported management strategy for MD-ACL is partial debridement with complete debridement, reduction plasty and conservative management as alternative options. Current operative management strategies place individuals at risk for ACL insufficiency. Information from this review can aid surgeons and clinicians in understanding what treatment options are best for this patient population, by understanding the reported clinical benefits and risks of each strategy. LEVEL OF EVIDENCE: IV.

Clinical outcomes of arthroscopic partial resection of mucoid degeneration of anterior cruciate ligament.

PURPOSE: Mucoid degeneration of the anterior cruciate ligament is rare condition; mucoid degeneration affects the range of motion of the knee with pain on terminal extension and terminal flexion. Arthroscopic treatment of the mucoid anterior cruciate ligament (ACL) is the treatment of choice. The purpose of this study was to provide demographic and clinical characteristic of mucoid degeneration of ACL and assess the outcomes of partial arthroscopic ACL resection. METHODS: Patients who underwent partial ACL resection for mucoid degeneration between February 2007 and February 2019 were considered for study eligibility. Patients were evaluated for International Knee Documentation Committee (IKDC), The Anterior Cruciate Ligament Return to Sport After Injury (ACL-RSI), The Knee injury and Osteoarthritis Outcome Score (KOOS) and Tegner activity scale. RESULTS: Sixty patients underwent partial ACL resection for mucoid degeneration of the ACL. Nine patients were lost to follow-up, 43 were males, the average age was 52.12±12.09 and a mean follow-up of 83.55±44.79 months. At final follow-up six patients underwent ACL reconstruction for ACL rupture (11.7%) at an average of 15.66±12 months. Patient satisfaction was at 71%. CONCLUSION: Arthroscopic partial resection of the ACL led to good clinical outcome for treating mucoid degeneration of the ACL.

Clinical and radiological comparison between partial and complete resection of the anterior cruciate ligament in patients with mucoid degeneration of the anterior cruciate ligament: a controlled clinical trial.

INTRODUCTION: The pathology of a mucoid degeneration of the anterior cruciate ligament (MDACL) has been mentioned in several publications but due to its rare incidence it is not a well-known pathology. Partial or complete resection of the ACL is the option of choice after failed non-surgical treatment. However, the success rate of both surgical techniques and the subsequent risk of an ACL instability is not known. The purpose of this study was to compare the clinical and radiological outcome between partial resection and complete resection of the ACL in patients with MDACL. MATERIALS AND METHODS: Patients with MDACL verified by MRI and persistent knee pain were treated by partial (Group I) or complete resection (Group II) of the ACL and were included in a controlled clinical trial after unsuccessful conservative treatment for at least 6 months. Demographic, clinical and radiological data including the thickness of ACL, ACL/intercondylar ratio, patient's age at the time of surgery, the presenting symptoms, range of motion and ligament stability assessed by the ACL ligament score (Lachman test) were collected. In addition, Tegner activity score and Lysholm score were evaluated preoperatively and at final follow-up after a minimum of 12 months. RESULTS: At final follow-up with a mean of 16.8 ± 8.8 months (range 12-41; Group I: 18.3 ± 9.7 vs. Group II: 15.3 ± 8.0; ns), all patients were pain free. Postoperatively, positive Lachman tests were noted in all patients (100%) in Group II (n = 5 patients with grade II and n = 5 patients with grade III). In Group I, 8 patients (80%) showed a negative Lachman test (grade I) and 2 patients (20%) a slightly elongated Lachman test with a firm stop (grade II). The mean knee flexion at follow-up examination was 132° ± 7° (range 120°-140°; Group I: 129° ± 9° vs. Group II: 135° ± 4°; ns). In pairwise comparison, flexion angle increased significantly in both groups (Group I: p = 0.0124 and Group II: p < 0.001). Pairwise comparison of thickness of the ACL and ACL/intercondylar ratio prior to and post-surgery in Group I showed non-significant differences. CONCLUSION: Both arthroscopic debridement and complete resection of the ACL lead to improvement of clinical and radiological findings in isolated MDACL. However, complete resection of the ACL will result in higher instability. Therefore, partial resection might be the better treatment option, especially in young patients with MDACL.

Radiologic findings associated with mucoid degeneration of the anterior cruciate ligament.

INTRODUCTION: Mucoid degeneration (MD) of the anterior cruciate ligament (ACL) is a well-recognized pathology characterized by the degradation of collagen fibers and infiltration of a mucoid-like substance. This study is to determine the anatomical associated factors for MD-ACL using radiographic and magnetic resonance imaging (MRI). MATERIALS AND METHODS: This was a retrospective study on patients who had undergone knee arthroscopy between 2011 and 2020. The patients with MD-ACL were defined and enrolled by the MRI and arthroscopy. Eventually, 52 patients in the MD-ACL group (group 1) and 52 patients in the control group (group 2) were enrolled, following sex and age matching. Radiologic evaluation included the assessment of Kellgren-Lawrence (K-L) grade, mechanical hip-knee-ankle (HKA) angle, posterior tibial slope (PTS) angle, and Insall-Salvati ratio. The notch width index and transverse notch angle were measured on MRI, and the grade of trochlear dysplasia was defined. Logistic regression analysis, receiver operating characteristic (ROC) curves, and area under curve (AUC) were performed. RESULTS: The ROM was significantly decreased in group 1, whereas the PTS angle was significantly larger in group 1. Combined ganglion cysts of ACL were found in 42/52 patients (80.7%) in group 1. The risk of MD-ACL was associated with a steeper PTS angle, increased Insall-Salvati ratio, male sex, higher K-L grade, and decreased transverse notch angle and notch width index. The cutoff values in ROC analysis were found to be ≤ 28.27% for the notch width index (AUC, 0.849; p < 0.001), > 12.2° for the PTS angle (AUC, 0.765; p < 0.001), and ≤ 47.4° for the transverse notch angle (AUC, 0.711; p < 0.001), but not significant for Insall-salvati ratio. CONCLUSION: A steeper PTS angle, decreased notch width index, and transverse notch angle are significantly associated with the presence of MD-ACL. These factors should be considered during diagnosis or when determining the treatment strategy for symptomatic MD-ACL patients. LEVEL OF EVIDENCE: Level IIIb.

Mucoid Pseudomonas aeruginosa Can Produce Calcium-Gelled Biofilms Independent of the Matrix Components Psl and CdrA.

Biofilms are aggregates of microorganisms embedded in an extracellular matrix comprised largely of exopolysaccharides (EPSs), nucleic acids, and proteins. Pseudomonas aeruginosa is an opportunistic human pathogen that is also a model organism for studying biofilms in the laboratory. Here, we define a novel program of biofilm development used by mucoid (alginate-overproducing) P. aeruginosa in the presence of elevated calcium. Calcium cations cross-link negatively charged alginate polymers, resulting in individual cells being suspended in an alginate gel. The formation of this type of structurally distinct biofilm is not reliant on the canonical biofilm EPS components Psl and Pel or the matrix protein CdrA. We also observed that mucoid P. aeruginosa biofilm cells do not have the typical elevated levels of the secondary messenger cyclic di-GMP (c-di-GMP), as expected of biofilm cells, nor does the overproduction of alginate rely on high c-di-GMP. This contrasts with nonmucoid biofilms in which the production of the matrix components Psl, Pel, and CdrA is positively regulated by elevated c-di-GMP. We further demonstrate that calcium-gelled alginate biofilms impede the penetration of the antibiotic tobramycin, thus protecting the biofilm community from antibiotic-mediated killing. Finally, we show that bacterial aggregates with a dispersed cell arrangement like laboratory-grown calcium-alginate biofilm structures are present in explanted cystic fibrosis (CF) lung samples. Our findings illustrate the diverse nature of biofilm formation and structure in P. aeruginosa. IMPORTANCE The opportunistic pathogen Pseudomonas aeruginosa produces a complex biofilm matrix comprised of exopolysaccharides (EPSs), nucleic acids, and proteins. P. aeruginosa biofilm formation canonically depends on a variable combination of the exopolysaccharides Psl and Pel and the matrix protein CdrA. We demonstrate that mucoid P. aeruginosa, which overproduces the EPS alginate, possesses an entirely alternate and calcium-dependent method of biofilm formation. These mucoid biofilm structures do not require Psl, Pel, or CdrA, and they display a unique organization of individually suspended cells similar to bacterial aggregates observed in cystic fibrosis airways. Furthermore, calcium-gelled mucoid biofilms impede the penetration and killing action of the antibiotic tobramycin, illustrating their potential clinical significance. Our findings highlight the compositional and structural variety of P. aeruginosa biofilm aggregates.

Invasive Streptococcus oralis Expressing Serotype 3 Pneumococcal Capsule, Japan.

We report 2 adult cases of invasive disease in Japan caused by Streptococcus oralis that expressed the serotype 3 pneumococcal capsule and formed mucoid colonies. Whole-genome sequencing revealed that the identical serotype 3 pneumococcal capsule locus and hyl fragment were recombined into the genomes of 2 distinct S. oralis strains.

Polyguluronate simulations shed light onto the therapeutic action of OligoG CF-5/20.

Chronic mucoid P. aeruginosa cystic fibrosis (CF) lung infections are associated with the development of a biofilm composed of anionic acetylated exopolysaccharide (EPS) alginate, electrostatically stabilised by extracellular Ca2+ ions. OligoG CF-5/20, a low molecular weight guluronate rich oligomer, is emerging as a novel therapeutic capable of disrupting mature P. aeruginosa biofilms. However, its method of therapeutic action on the mucoid biofilm EPS is not definitively known at a molecular level. This work, utilising molecular dynamics (MD) and Density-Functional Theory (DFT), has revealed that OligoG CF-5/20 interaction with the EPS is facilitated solely through bridging Ca2+ ions, which are not liberated from their native EPS binding sites upon OligoG CF-5/20 dispersal, suggesting that OligoG CF-5/20 does not cause disruptions to mature P. aeruginosa biofilms through breaking EPS-Ca2+-EPS ionic cross-links. Rather it is likely that the therapeutic activity arises from sequestering free Ca2+ ions and preventing further Ca2+ induced EPS aggregation.

Intraarticular injection of the interphalangeal joint for therapy of digital mucoid cysts.

Mucoid cysts are associated with osteoarthritis (OA) of the digital joints and frequently recur after needle drainage, injection, or surgical ablation. This study determined whether intraarticular injection of the adjacent interphalangeal joint rather than the cyst itself might be effective in resolving digital mucoid cysts. Using paired case series design and sterile technique, 25 consecutive OA digital joints with an adjacent mucoid cyst underwent dorsal non-transtendinous intraarticular injection with a 25-gauge needle and 20-mg triamcinolone acetonide, followed by puncture and manual expression of cyst fluid. Patient pain was measured with the 10-cm Visual Analogue Pain Scale prior to the procedure and at 6 months. Cyst resolution was determined at 6 months and 3 years. The subjects were 61.0 ± 7.7 years old and 60% (15/25) female. Mucoid cysts were adjacent to 19 distal interphalangeal, 3 metacarpophalangeal, and 3 interphalangeal joints. Pre-procedural pain was 4.7 ± 1.0; procedural pain was 6.2 ± 0.6 cm, and post-procedural pain at 6 months was 1.2 ± 0.8 cm (74.5% reduction, 95% CI of difference: 3.0 < 3.5 < 4.0 (p < 0.0001)). 84% (21/25) of the cysts resolved at 6 months; however, 60% (15/25) of the mucoid cysts recurred within 3 years and required retreatment (14 adjacent joints re-injected and 1 ablative cyst surgery). No complications were noted. Intraarticular corticosteroid injection using a dorsal non-transtendinous approach of the joint adjacent to a mucoid cyst is effective resolving cysts and reducing pain at 6 months; however, 60% of mucoid cysts reoccur within 3 years and may require reinjection or surgery.Trial registration: This was not a clinical trial.

Relationship between the aortic root Z-score and degree of translamellar mucoid extracellular matrix accumulation.

PURPOSES: A retrospective analysis was performed to compare the pathological findings and aortic root Z-score in patients with and without connective tissue disease (CTD). METHODS: Twenty-two patients {47.5 [15-85] years old, 18 males} underwent surgery for aortic root dilatation without aortic dissection: 10 {40 [16-59] years old} with CTD and 12 {57.5 [15-85] years old} without CTD (non-CTD; p = 0.049). Systemic hypertension (p = 0.043) and the degree of preoperative aortic regurgitation (p = 0.017) were higher in the non-CTD patients than in the CTD patients. RESULTS: The diameters of the sinotubular junction (STJ) (p = 0.048) and ascending aorta (Asc.Ao.) (p = 0.020) and the Z-scores of the STJ (p = 0.027) and Asc.Ao. (p = 0.009) were significantly higher in the non-CTD patients than in the CTD patients. The degree of translamellar mucoid extracellular matrix accumulation (T-MEMA) of the Asc.Ao. was significantly higher in the non-CTD patients than in the CTD patients (p = 0.037) and was significantly correlated with the Z-scores of the aorta (R = 0.746, p < 0.01 in the sinus of Valsalva and R = 0.382, p = 0.031 in the Asc.Ao.), although there was no significant correlation between the diameter of the STJ and that of Asc.Ao. CONCLUSIONS: In non-CTD patients, not only the aortic root but also Asc.Ao. tended to dilate with age, and a significant correlation between the Z-scores of the aorta root and the Asc.Ao. and the degrees of T-MEMA was observed.

Comparative genome analysis of multidrug-resistant Pseudomonas aeruginosa JNQH-PA57, a clinically isolated mucoid strain with comprehensive carbapenem resistance mechanisms.

BACKGROUND: The prevalence of clinical multidrug-resistant (MDR) Pseudomonas aeruginosa has been increasing rapidly worldwide over the years and responsible for a wide range of acute and chronic infections with high mortalities. Although hundreds of complete genomes of clinical P. aeruginosa isolates have been sequenced, only a few complete genomes of mucoid strains are available, limiting a comprehensive understanding of this important group of opportunistic pathogens. Herein, the complete genome of a clinically isolated mucoid strain P. aeruginosa JNQH-PA57 was sequenced and assembled using Illumina and Oxford nanopore sequencing technologies. Genomic features, phylogenetic relationships, and comparative genomics of this pathogen were comprehensively analyzed using various bioinformatics tools. A series of phenotypic and molecular-genetic tests were conducted to investigate the mechanisms of carbapenem resistance in this strain. RESULTS: Several genomic features of MDR P. aeruginosa JNQH-PA57 were identified based on the whole-genome sequencing. We found that the accessory genome of JNQH-PA57 including several prophages, genomic islands, as well as a PAPI-1 family integrative and conjugative element (ICE), mainly contributed to the larger genome of this strain (6,747,067 bp) compared to other popular P. aeruginosa strains (with an average genome size of 6,445,223 bp) listed in Pseudomonas Genome Database. Colony morphology analysis and biofilm crystal staining assay respectively demonstrated an enhanced alginate production and a thicker biofilm formation capability of JNQH-PA57. A deleted mutation at nt 424 presented in mucA gene, resulted in the upregulated expression of a sigma-factor AlgU and a GDP mannose dehydrogenase AlgD, which might explain the mucoid phenotype of this strain. As for the carbapenem resistance mechanisms, our results revealed that the interplay between impaired OprD porin, chromosomal ß-lactamase OXA-488 expression, MexAB-OprM and MexXY-OprM efflux pumps overexpression, synergistically with the alginates-overproducing protective biofilm, conferred the high carbapenem resistance to P. aeruginosa JNQH-PA57. CONCLUSION: Based on the genome analysis, we could demonstrate that the upregulated expression of algU and algD, which due to the truncation variant of MucA, might account for the mucoid phenotype of JNQH-PA57. Moreover, the resistance to carbapenem in P. aeruginosa JNQH-PA57 is multifactorial. The dataset presented in this study provided an essential genetic basis for the comprehensive cognition of the physiology, pathogenicity, and carbapenem resistance mechanisms of this clinical mucoid strain.

A naturally occurring point mutation in the rocA gene of Streptococcus pyogenes confers the highly virulent phenotype.

INTRODUCTION: Mucoid (MTB313) and nonmucoid (MTB314) strains of group A streptococcus (GAS) emm (antiphagocytic M protein) type 1 were simultaneously isolated from a single patient suffering from streptococcal meningitis. In a CD46-expressing transgenic (CD46 Tg) mouse model of subcutaneous infection into both hind footpads with MTB313 or MTB314, MTB313 showed considerably higher virulence than MTB314. METHODS: The comparative genomic analysis based on the whole-genome sequencing revealed that MTB313 possessed an amber codon within rocA (sensory transduction protein kinase), but MTB314 did not carry this stop codon. Thereafter, MAT101 was generated from MTB313 by introducing pRocA, which contained the full-length rocA from MTB314, into the cloning plasmid pLZ12-Km2. MAT100 was also generated by introducing pLZ12-Km2 into MTB313. RESULTS: Although MTB313 and MAT100 showed large quantities of cell-associated hyaluronic acid (HA) in the culture pellets, MTB314 and MAT101 showed small quantities of HA production. Finally, higher mortalities were observed in the MTB313- or MAT100-infected CD46 Tg mice than the MTB314- or MAT101-infected CD46 Tg mice. CONCLUSIONS: These data indicate the possibility that a spontaneous point mutation in the rocA gene led to the highly virulent phenotype of M1 GAS.