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BACKGROUND: The use of piperacillin/tazobactam with vancomycin as empirical antimicrobial therapy (EAT) for prosthetic joint infection (PJI) has been associated with an increased risk of acute kidney injury (AKI), leading us to propose cefepime as an alternative since 2017 in our reference centre. OBJECTIVES: To compare microbiological efficacy and tolerance of these two EAT strategies. METHODS: All adult patients with PJI empirically treated with vancomycin+cefepime (n = 89) were enrolled in a prospective observational study and matched with vancomycin+piperacillin/tazobactam-treated historical controls (n = 89) according to a propensity score including age, baseline renal function and concomitant use of other nephrotoxic agents. The two groups were compared using Kaplan-Meier curve analysis, and non-parametric tests regarding the proportion of efficacious empirical regimen and the incidence of empirical therapy-related adverse events (AE). RESULTS: Among 146 (82.0%) documented infections, the EAT was considered efficacious in 77 (98.7%) and 65 (98.5%) of the piperacillin/tazobactam- and cefepime-treated patients, respectively (P = 1.000). The rate of AE, particularly AKI, was significantly higher in the vancomycin+piperacillin/tazobactam group [n = 27 (30.3%) for all AE and 23 (25.8%) for AKI] compared with the vancomycin+cefepime [n = 13 (14.6%) and 6 (6.7%)] group (P = 0.019 and <0.001, respectively), leading to premature EAT discontinuation in 20 (22.5%) and 5 (5.6%) patients (P = 0.002). The two groups were not significantly different regarding their comorbidities, and AKI incidence was not related to vancomycin plasma overexposure. CONCLUSIONS: Based on the susceptibility profile of bacterial isolates from included patients, microbiological efficacy of both strategies was expected to be similar, but vancomycin + cefepime was associated with a significantly lower incidence of AKI.
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Lesión Renal Aguda , Antiinfecciosos , Lesión Renal Aguda/inducido químicamente , Lesión Renal Aguda/tratamiento farmacológico , Adulto , Antibacterianos/efectos adversos , Cefepima , Estudios de Cohortes , Quimioterapia Combinada , Humanos , Ácido Penicilánico/efectos adversos , Piperacilina/efectos adversos , Combinación Piperacilina y Tazobactam , Estudios Retrospectivos , Vancomicina/efectos adversosRESUMEN
Introduction: In patients undergoing a « debridement, antibiotics, and implant retention ¼ (DAIR) procedure for acute staphylococcal prosthetic joint infection (PJI), post-operative treatment with rifampin has been associated with a higher probability of success.(1,2) However, it is not known whether it is the total dose, delay of introduction or length of therapy with rifampin that is most strongly associated with the observed improved outcomes. Methods: A multicentric, retrospective cohort study of patients with acute staphylococcal hip and knee PJI treated with DAIR between January 2011 and December 2016. Failure of the DAIR procedure was defined as persistent infection, need for another surgery or death. We fitted logistic and Cox regression multivariate models to identify predictors of DAIR failure. We compared Kaplan-Meier estimates of failure probability in different levels of the 3 variables of interest - total dose, delay of introduction or length of therapy with rifampin - with the log-rank test. Results: 79 patients included (median age 71 years [63.5-81]; 55 men [70%]), including 54 (68%) DAIR successes and 25 (32%) DAIR failures. Patients observed for a median of 435 days [IQR 107.5-834]. Median ASA score significantly lower in DAIR successes than in DAIR failures (2 vs. 3, respectively p = 0.011). Bacterial cultures revealed 65 (82.3%) S. aureus and 16 (20.3%) coagulase negative staphylococci, with 2 patients being infected simultaneously with S. aureus and CNS. Among S. aureus isolates, 7 (10.8%) resistant to methicillin; 2 (3.1 %) resistant to rifampin. Median duration of antimicrobial therapy was 85 days [IQR 28.5-97.8]. Fifty-eight patients (73.4%) received rifampin at a median dose of 14.6 mg/kg/day |IQR 13-16.7], started at a median delay of 8.5 days [IQR, 4-7.5] after debridement surgery. Twenty-one patients (26.6%) developed a drug-related adverse event, leading to rifampin interruption in 6 of them (7.6% of total cohort). Determinants of DAIR failure were rifampin use (HR 0.17, IC [0.06, 0.45], p-value <0.001), association of rifampin with a fluoroquinolone (HR 0.19, IC [0.07, 0.53], p-value = 0.002) and duration of rifampin therapy (HR 0.97, IC [0.95, 1], p-value = 0.022). We did not observe a significant difference between DAIR successes and failures in rifampin use, dose and delay of introduction. In a multivariate Cox model, only duration of rifampin therapy was significantly associated with DAIR failure. Kaplan Meier estimate of DAIR failure probability was significantly higher in patients receiving less than 14 days of rifampin in comparison with those receiving more than 14 days of rifampin (p = 0.0017). Conclusion: Duration of rifampin therapy is a key determinant of improved outcomes in early-onset acute prosthetic joint infection due to Staphylococcus treated with DAIR.
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OBJECTIVE: To describe the epidemiology of pubic osteomyelitis (PO) and to look for factors associated with treatment failure. METHOD: Retrospective study describing PO according to outcome: success or failure of initial management. Factors associated with failure determined by univariate Cox analysis. Kaplan-Meier curve compared between groups by log-rank test. RESULTS: Twenty-five patients were included over a 13-year period; 24% of PO had blood-borne infection. Failure (44%) was always observed in chronic postoperative presentations (76%). Fistula (32%) was only observed in postoperative presentations and was significantly associated with failure (HR 5.1; P=0.011). Other risk factors were pelvic malignant tumor history, abscess, infection due to extended-spectrum beta-lactamase-producing Enterobacteriaceae, and polymicrobial infection. CONCLUSION: PO is most often a chronic postoperative polymicrobial infection in patients with comorbidities at high risk of relapse. Studies in larger cohorts could assess the efficacy of more aggressive surgical strategies in patients at high risk of failure.
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Osteomielitis , Absceso , Enterobacteriaceae , Humanos , Osteomielitis/epidemiología , Osteomielitis/terapia , Estudios Retrospectivos , Factores de Riesgo , Insuficiencia del TratamientoRESUMEN
OBJECTIVE: We aimed to describe the use of subcutaneous teicoplanin as an alternative for the treatment of staphylococcal bone and joint infections. METHODS: A retrospective multicentric cohort (2002-2015) was conducted with patients receiving subcutaneous teicoplanin for a staphylococcal bone and joint infection. RESULTS: Forty patients were assessed. A median loading dose of 9.4 mg/kg/12h (IQR, 6.1-13.1) was administered to 35 patients, subcutaneously for 18 of them. Thirteen of these patients received three injections per week. No excess risk of failure was identified. The trough level was not significantly different between the various routes (p=0.462), and was significantly higher if the loading dose was≥9 mg/kg/injection (p<10-3). CONCLUSION: The use of subcutaneous teicoplanin seems to be acceptable as an alternative to other routes of administration for antibiotics.
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Antibacterianos/administración & dosificación , Enfermedades Óseas/tratamiento farmacológico , Enfermedades Óseas/microbiología , Artropatías/tratamiento farmacológico , Artropatías/microbiología , Infecciones Estafilocócicas/tratamiento farmacológico , Teicoplanina/administración & dosificación , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Inyecciones Subcutáneas , Masculino , Persona de Mediana Edad , Estudios RetrospectivosRESUMEN
Solid organ transplant candidates/recipients are at risk of mycobacterial infections. Although guidelines on the management of latent tuberculosis infection and active tuberculosis are available for solid organ transplant recipients, limited guidance focuses on end-stage liver disease or liver transplant recipients who require management in a referral center. Therapeutic challenges arise from direct antituberculosis drug-related hepatotoxicity, and substantial metabolic interactions between immunosuppressive and antituberculosis drugs. Another issue is the optimal timing of therapy with regards to the time of transplantation. This review focuses on the importance of tuberculosis screening with immunological tests, challenges in the diagnosis, management, and treatment of latent tuberculosis infection and active tuberculosis, as well as risk assessment for active tuberculosis in the critical peri-liver transplantation period. We detail therapeutic adjustments required for the management of antituberculosis drugs in latent tuberculosis infection and active tuberculosis, particularly when concomitantly using rifampicin and immunosuppressive drugs.
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Trasplante de Hígado , Receptores de Trasplantes , Tuberculosis/diagnóstico , Tuberculosis/terapia , Antituberculosos/uso terapéutico , Geografía , Humanos , Inmunosupresores/uso terapéutico , Fallo Hepático/complicaciones , Fallo Hepático/terapia , Prevalencia , Acondicionamiento Pretrasplante/efectos adversos , Acondicionamiento Pretrasplante/métodos , Tuberculosis/complicaciones , Tuberculosis/epidemiologíaRESUMEN
OBJECTIVES: The high microbiologic diversity encountered in prosthetic joint infection (PJI) makes the choice of empirical antimicrobial therapies challenging, especially in cases of implant retention or one-stage exchange. Despite the risk of dysbiosis and toxicity, the combination of vancomycin with a broad-spectrum ß-lactam is currently recommended in all cases, even if Gram-negative bacilli (GNB) might be less represented in late PJI. In this context, this study aimed to describe the microbiologic epidemiology of PJI according to the chronology of infection. METHODS: This prospective cohort study (2011-2016) evaluated the microbiologic aetiology of 567 PJI according to time of occurrence from prosthesis implantation-early (<3 months), delayed (3-12 months) and late (>12 months)-as well as mechanism of acquisition. RESULTS: Initial microbiologic documentation (n = 511; 90.1%) disclosed 164 (28.9%) Staphylococcus aureus (including 26 (16.1%) methicillin-resistant S. aureus), 162 (28.6%) coagulase-negative staphylococci (including 81 (59.1%) methicillin-resistant coagulase-negative staphylococci), 80 (14.1%) Enterobacteriaceae, 74 (13.1%) streptococci and 60 (10.6%) Cutibacterium acnes. Considering nonhaematogenous late PJI (n = 182), Enterobacteriaceae (n = 7; 3.8%) were less represented than in the first year after implantation (n = 56; 17.2%; p <0.001), without difference regarding nonfermenting GNB (4.6% and 2.7%, respectively). The prevalence of anaerobes (n = 40; 21.9%; including 32 (80.0%) C. acnes) was higher in late PJI (p <0.001). Consequently, a broad-spectrum ß-lactam might be useful in 12 patients (6.6%) with late PJI only compared to 66 patients (20.3%) with early/delayed PJI (p <0.001). CONCLUSIONS: Considering the minority amount of GNB in late postoperative PJI, the empirical use of a broad-spectrum ß-lactam should be reconsidered, especially when a two-stage exchange is planned.
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Antibacterianos/uso terapéutico , Artritis Infecciosa/tratamiento farmacológico , Artritis Infecciosa/microbiología , Fenómenos Fisiológicos Bacterianos , Prótesis Articulares/efectos adversos , Infecciones Relacionadas con Prótesis/tratamiento farmacológico , Infecciones Relacionadas con Prótesis/microbiología , Anciano , Bacterias/crecimiento & desarrollo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Factores de TiempoRESUMEN
OBJECTIVES: To evaluate outpatient parenteral antibiotic therapy (OPAT) practices in a French rural area. MATERIAL AND METHODS: Descriptive study assessing knowledge, practices, and limitations of OPAT use among hospital practitioners (HP), family physicians (FP), and private nurses (PN). RESULTS: OPAT (mainly ceftriaxone and penicillins) was used by 69.6%, 73.3%, and 97.7% of the 23 HPs, 45 FPs, and 46 PNs mostly for respiratory or urinary tract infections, bacteremia, and/or multidrug-resistant bacterial infections. Overall, 65.2% of HPs and 37.8% of FPs were in contact with an infectious disease specialist. Knowledge of OPAT benefits and risks was lower for FPs than HPs. The main obstacles were the patient's geographic isolation (HPs), the availability of a venous catheter, the lack of training (FPs), and the expected OPAT-associated overwork (PNs). CONCLUSION: OPAT practice is weak in rural areas. Declared obstacles constitute fields of improvement for its essential expansion.
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Atención Ambulatoria , Antibacterianos/administración & dosificación , Infecciones Bacterianas/tratamiento farmacológico , Adulto , Quimioterapia Combinada , Femenino , Francia , Conocimientos, Actitudes y Práctica en Salud , Humanos , Inyecciones , Masculino , Persona de Mediana Edad , Nutrición Parenteral , Servicios de Salud Rural , Factores de TiempoRESUMEN
OBJECTIVES: To assess the clinical experience of tigecycline-based salvage therapy in patients presenting with Bone and Joint Infections (BJI). PATIENTS AND METHODS: Multicenter retrospective cohort study in France and Turkey (2007-2014). RESULTS: Thirty-six patients (age 58.2±17.8 years; 21 men) were included. The most frequently isolated bacteria were Enterobacteriaceae and staphylococci. Tigecycline (50mg BID, mainly in combination (69.4%), mean duration of 58 days) was indicated for multidrug resistance (90.6%) and/or previous antibiotic intolerance (36.1%), and/or as second- or third-line therapy (69.4%). Six patients (16.7%) experienced early treatment discontinuation for adverse event (4 severe vomiting, 1 pancreatitis, 1 asymptomatic lipase increase). Clinical success was observed in 23 of 30 assessable patients who completed the tigecycline therapy (mean follow-up: 54.1±57.7 weeks). CONCLUSION: Prolonged tigecycline-based therapy could be an alternative in patients presenting with BJI requiring salvage therapy, especially if multidrug-resistant Enterobacteriaceae and/or staphylococci are involved.
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Antibacterianos/uso terapéutico , Artritis Infecciosa/tratamiento farmacológico , Minociclina/análogos & derivados , Osteítis/tratamiento farmacológico , Terapia Recuperativa , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/efectos adversos , Estudios de Cohortes , Evaluación de Medicamentos , Farmacorresistencia Bacteriana Múltiple , Quimioterapia Combinada , Femenino , Estudios de Seguimiento , Francia , Humanos , Masculino , Persona de Mediana Edad , Minociclina/efectos adversos , Minociclina/uso terapéutico , Pancreatitis/inducido químicamente , Estudios Retrospectivos , Tigeciclina , Turquía , Vómitos/inducido químicamenteRESUMEN
Brucellosis is usually acquired by humans through contact with infected animals or the consumption of raw milk from infected ruminants. Brucella suis biovar 2 (BSB2) is mainly encountered in hares and wild boars (Sus scrofa), and is known to have very low pathogenicity to humans with only two case reports published in the literature. Human cases of brucellosis caused by BSB2 were identified through the national mandatory notification of brucellosis. The identification of the bacterium species and biovar were confirmed by the national reference laboratory. Epidemiological data were obtained during medical follow-up visits. Seven human cases were identified between 2004 and 2016, all confirmed by the isolation of BSB2 in clinical specimens. All patients had direct contact with wild boars while hunting or preparing wild boar meat for consumption. Five patients had chronic medical conditions possibly responsible for an increased risk of infection. Our findings suggest that BSB2 might be an emerging pathogen in hunters with massive exposure through the dressing of wild boar carcasses. Hunters, especially those with chronic medical conditions, should be informed about the risk of BSB2 infection and should receive information on protective measures.
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Brucella suis/aislamiento & purificación , Brucelosis/diagnóstico , Adulto , Anciano , Animales , Brucelosis/microbiología , Femenino , Francia , Humanos , Actividades Recreativas , Masculino , Persona de Mediana Edad , Factores de Riesgo , Sus scrofaRESUMEN
Actinomycosis is a rare bacterial disease caused by Actinomyces spp., an anaerobic bacteria from the oropharynx, digestive, and female genital tracts. Initial clinical presentation often mimics malignancy, which can lead to a delay in diagnosis. Cervico-facial, genitourinary, digestive, and respiratory features are the most frequent. Few cases are reported in children and risk factors are not well known in this population. We report on the case of an 8-year-old boy with disseminated actinomycosis with cervico-facial, pulmonary, and bone involvement caused by Actinomyces israelii. The infiltrative appearance initially suggested malignancy and the patient was started on chemotherapy for presumed histiocytosis. Evaluation of subsequent tissue samples demonstrated the presence of filamentous structures consistent with fungal or filamentous bacterial infection. Prolonged culture yielded the correct diagnosis. The patient had a severe allergic reaction to piperacillin/tazobactam and was therefore transitioned to clindamycin to complete a 9-month course. This treatment, which has not been reported in children, led to a favorable clinical, biological, and radiological response, with a good clinical tolerance.
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Actinomicosis/tratamiento farmacológico , Clindamicina/uso terapéutico , Actinomicosis/diagnóstico , Actinomicosis/patología , Biopsia , Niño , Diagnóstico Tardío , Diagnóstico Diferencial , Humanos , Cuidados a Largo Plazo , Imagen por Resonancia Magnética , Masculino , Alveolos Pulmonares/patologíaRESUMEN
BACKGROUND: There are only few cases of renal pathology induced by Lyme borreliosis in the literature, as this damage is rare and uncommon in humans. This patient is the first case of minimal change glomerular disease associated with chronic Lyme borreliosis. CASE PRESENTATION: A 65-year-old Caucasian woman was admitted for an acute edematous syndrome related to a nephrotic syndrome. Clinical examination revealed violaceous skin lesions of the right calf and the gluteal region that occurred 2 years ago. Serological tests were positive for Lyme borreliosis and skin biopsy revealed lesions of chronic atrophic acrodermatitis. Renal biopsy showed minimal change glomerular disease. The skin lesions and the nephrotic syndrome resolved with a sequential treatment with first ceftriaxone and then corticosteroids. CONCLUSION: We report here the first case of minimal change disease associated with Lyme borreliosis. The pathogenesis of minimal change disease in the setting of Lyme disease is discussed but the association of Lyme and minimal change disease may imply a synergistic effect of phenotypic and bacterial factors. Regression of proteinuria after a sequential treatment with ceftriaxone and corticosteroids seems to strengthen this conceivable association.
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Acrodermatitis/etiología , Enfermedad de Lyme/complicaciones , Nefrosis Lipoidea/etiología , Síndrome Nefrótico/etiología , Acrodermatitis/diagnóstico , Acrodermatitis/patología , Anciano , Antibacterianos/uso terapéutico , Ceftriaxona/uso terapéutico , Enfermedad Crónica , Femenino , Glucocorticoides/uso terapéutico , Humanos , Riñón/patología , Enfermedad de Lyme/diagnóstico , Enfermedad de Lyme/tratamiento farmacológico , Nefrosis Lipoidea/diagnóstico , Nefrosis Lipoidea/tratamiento farmacológico , Nefrosis Lipoidea/patología , Síndrome Nefrótico/diagnóstico , Prednisolona/uso terapéutico , Piel/patologíaAsunto(s)
Artritis Infecciosa , Pristinamicina , Antibacterianos , Humanos , Infecciones EstafilocócicasAsunto(s)
Antituberculosos/uso terapéutico , Artroplastía de Reemplazo de Hombro/efectos adversos , Mycobacterium bovis/aislamiento & purificación , Infecciones Relacionadas con Prótesis/microbiología , Prótesis de Hombro/microbiología , Infección de la Herida Quirúrgica/microbiología , Tuberculosis Osteoarticular/microbiología , Anciano , Animales , Antibacterianos/uso terapéutico , Coinfección/tratamiento farmacológico , Coinfección/microbiología , Terapia Combinada , Desbridamiento , Remoción de Dispositivos , Resultado Fatal , Femenino , Infecciones por Bacterias Grampositivas/etiología , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Huésped Inmunocomprometido , Obstrucción Intestinal/etiología , Obstrucción Intestinal/cirugía , Leche/efectos adversos , Leche/microbiología , Propionibacterium acnes/aislamiento & purificación , Infecciones Relacionadas con Prótesis/tratamiento farmacológico , Infecciones Relacionadas con Prótesis/cirugía , Fibrosis Pulmonar/etiología , Prótesis de Hombro/efectos adversos , Infección de la Herida Quirúrgica/tratamiento farmacológico , Infección de la Herida Quirúrgica/cirugía , Tuberculosis Osteoarticular/tratamiento farmacológico , Tuberculosis Osteoarticular/cirugía , Tuberculosis Pulmonar/tratamiento farmacológico , Tuberculosis Pulmonar/etiologíaRESUMEN
Actinomycosis is a rare chronic and multifaceted disease caused by Actinomyces species frequently mimicking malignancy or other chronic granulomatous lung diseases. We report 4 original presentations of actinomycosis arising under supposed penicillin prophylaxis in allogeneic stem cell transplantation recipients.
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Actinomicosis/etiología , Actinomicosis/prevención & control , Antibacterianos/uso terapéutico , Profilaxis Antibiótica , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Enfermedades Pulmonares/etiología , Enfermedades Pulmonares/prevención & control , Actinomyces/aislamiento & purificación , Actinomicosis/diagnóstico por imagen , Actinomicosis/microbiología , Adulto , Antibacterianos/administración & dosificación , Líquido del Lavado Bronquioalveolar/microbiología , Femenino , Humanos , Enfermedades Pulmonares/diagnóstico por imagen , Enfermedades Pulmonares/microbiología , Masculino , Persona de Mediana Edad , Penicilinas/administración & dosificación , Penicilinas/uso terapéutico , Tomografía Computarizada por Rayos X , Trasplante Homólogo/efectos adversosAsunto(s)
Prótesis de Cadera/efectos adversos , Prótesis de la Rodilla/efectos adversos , Prótesis Articulares de Metal sobre Metal/efectos adversos , Infecciones Relacionadas con Prótesis/etiología , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infecciones Relacionadas con Prótesis/diagnóstico , Infecciones Relacionadas con Prótesis/terapiaRESUMEN
INTRODUCTION: Tuberculosis-related morbidity and mortality remain important. Emergence and diffusion of multidrug-resistance tuberculosis (MDR-TB) is a global public health concern. Cases of MDR-TB in children are a sentinel event indicating the spread of a mycobacterial strain within a community. Latent TB precedes MDR-TB and screening and follow-up of contact individuals are key points of TB infection control. METHODS: We performed the case-investigation of 20 adult cases of MDR-TB managed in our institution. RESULTS: Forty-six pediatric contact individuals were identified. A high proportion of these children were lost to follow-up (80% at 12 months), showing that monitoring this reservoir population with migrant history is challenging. Five (11%) children presented a secondary infection: one child was diagnosed with active TB infection (positive tuberculin skin test associated with abnormalities on chest computer tomography [CT] scan). Four children were diagnosed with latent TB infection (isolated positive tuberculin skin test with normal CT scan). Two of these children received a treatment adjusted to the strain of the index case. DISCUSSION: In the setting of emerging MDR-TB, tuberculin skin test may be likely replaced by specific interferon-gamma release assays (IGRA), independent of prior BCG vaccination. In addition, chest CT scan is preferred to chest X-ray to detect TB lesions. The management of latent TB infection is controversial: immediate treatment with second-line anti-TB drugs adapted to the index case strain or, consistently with WHO guidelines, a simple follow-up with subsequent treatment in case of active TB.
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Tuberculosis Resistente a Múltiples Medicamentos/epidemiología , Tuberculosis Resistente a Múltiples Medicamentos/transmisión , Amicacina/uso terapéutico , Antibacterianos/uso terapéutico , Niño , Preescolar , Femenino , Francia/epidemiología , Humanos , Lactante , Tuberculosis Latente/diagnóstico , Tuberculosis Latente/tratamiento farmacológico , Tuberculosis Latente/epidemiología , Levofloxacino/uso terapéutico , Perdida de Seguimiento , Masculino , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológicoRESUMEN
Biofilm formation, intra-osteoblastic persistence, small-colony variants (SCVs) and the dysregulation of agr, the major virulence regulon, are possibly involved in staphylococcal bone and joint infection (BJI) pathogenesis. We aimed to investigate the contributions of these mechanisms among a collection of 95 Staphylococcus aureus clinical isolates from 64 acute (67.4%) and 31 chronic (32.6%) first episodes of BJI. The included isolates were compared for internalization rate, cell damage and SCV intracellular emergence using an ex vivo model of human osteoblast infection. Biofilm formation was assessed in a microbead immobilization assay (BioFilm Ring test). Virulence gene profiles were assessed by DNA microarray. Seventeen different clonal complexes were identified among the screened collection. The staphylococcal internalization rate in osteoblasts was significantly higher for chronic than acute BJI isolates, regardless of the genetic background. Conversely, no differences regarding cytotoxicity, SCV emergence, biofilm formation and virulence gene distribution were observed. Additionally, agr dysfunction, detected by the lack of delta-toxin production using whole-cell matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) analysis (n = 15; 15.8%), was significantly associated with BJI chronicity, osteoblast invasion and biofilm formation. These findings provide new insights into MSSA BJI pathogenesis, suggesting the correlation between chronicity and staphylococcal osteoblast invasion. This adaptive mechanism, along with biofilm formation, is associated with agr dysfunction, which can be routinely assessed by delta-toxin detection using MALDI-TOF spectrum analysis, possibly providing clinicians with a diagnostic marker of BJI chronicity at the time of diagnosis.