BackgroundDespite advances in antimicrobial and surgical therapy, septic arthritis remains a rheumatologic emergency that can lead to rapid joint destruction and irreversible loss of function. In adults, Staphylococcus aureus is the most common microorganism isolated from native joints. Streptococcus gordonii is a prominent member of the viridans group of oral bacteria and is among the bacteria most frequently identified as being primary agent of subacute bacterial endocarditis. To the best of our knowledge, Streptococcus gordonii has not yet been described as agent of septic arthritis.Case PresentationWe describe here two cases of septic arthritis due to Streptococcus gordonii. It gives us an opportunity to review epidemiology, diagnosis criteria and management of septic arthritis.ConclusionAlthough implication of S. gordonii as aetiologic agent of subacute endocarditis is well known, this organism is a rare cause of septic arthritis. In this case, the exclusion of associated endocarditis is warranted.

Bacterial pathogens are the most frequent cause of pneumonia after transplantation. Early after transplantation, recipients are at higher risk for nosocomial infections. The most commonly encountered pathogens during this period are gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa …), but gram-positive coccus such as Staphylococcus aureus or Streptococcus pneumoniae and anaerobic bacteria can also be found. Empirical antibiotic therapy should be guided by previous colonisation of the recipient and bacterial resistance pattern in the hospital. Six months after transplantation, pneumonias are mostly due to community-acquired bacteria (S. pneumonia, H. influenza, Mycoplasma, Chlamydia and others). Opportunistic pathogens take advantage of the state of immunosuppression which is usually highest from one to six months after transplantation. During this period, but also occurring many years later in the setting of a chronically depressed immune system, bacterial pathogens with low intrinsic virulence can cause pneumonia. The diagnosis of pneumonia caused by opportunistic pathogens can be challenging. The delay in diagnosis preventing the early instauration of adequate treatment in kidney transplant recipients with a depressed immune system, frequently coupled with co-morbid conditions and a state of frailty, will affect prognosis and outcome, increasing morbidity and mortality. This review will focus on the most common opportunistic bacterial pathogens causing pneumonia in kidney transplant recipients: Legionella, Nocardia, Mycobacterium tuberculosis/nontuberculous, and Rhodococcus. Recognition of their specificities in the setting of immunosuppression will allow early diagnosis, crucial for initiation of effective therapy and successful outcome. Interactions with immunosuppressive therapy should be considered as well as reducing immunosuppression if necessary.

Osteonecrosis of the femoral head (ONFH) typically affects relatively young, active patients and frequently follows an unrelenting course resulting in considerable loss of function. In human immunodeficiency virus-infected patients, ONFH is a growing problem. Etiology, pathogenesis, and treatment of ONFH in these patients remain controversial. We analyzed retrospectively patients with ONFH in a series of 815 patients followed in our AIDS reference center. Six patients out of the 815 were affected by ONFH (0.74%). The sex ratio was 1. Two of the six patients (33.3%) had no evidence of risk factor, whereas four patients (66.6%) had risk factors. One patient had three cumulated risk factors which were corticosteroids, chemotherapy, and radiotherapy. For this patient, the onset time for ONFH was shorter (36 months). It is difficult to attribute the effect to any single class of antiretroviral agents because combination therapy is standard of care, and a change in therapies is common. All classes of antiretroviral drugs have been used: protease inhibitors (mean use duration of 15.2 months before the ONFH onset), non-nucleoside reverse transcriptase inhibitors (12 months), and nucleoside reverse transcriptase inhibitors (40.5 months). ONFH was bilateral in four cases (66.6%) and unilateral in two cases (33.3%). One patient had other osteonecrosis location (both shoulders). ONFH was classified on plain radiography stage IV in five patients and stage III in one patient. All patients received initial medical treatment. It consisted of painkillers and non-weight bearing of the hip. All were finally operated on by total hip arthroplasty (THA). The average interval between ONFH diagnosis and the first THA was 10.3 months for the six patients. A controlateral THA was performed for three patients after a mean interval of 23.3 months after ONFH diagnosis. Of the nine implanted prostheses, four were cemented, four were cementless, and one was resurfacing prosthesis.

Establishing the etiology of invasive fungal infections is important to guide therapeutic options and for epidemiologic purposes. Formalin-fixed, paraffin-embedded (FFPE) tissue specimens from patients with proven invasive fungal infections are valuable to determine the etiology of systemic fungal infections. We compared different polymerase chain reaction (PCR) amplification strategies from FFPE tissue blocks to identify agents of invasive fungal infections. We found that specific PCR assays show superior sensitivity in the identification of DNA of Mucorales and Aspergillus and mixed infections caused by both as compared to broad-range PCR assays. Shorter amplicon lengths and less detection of contaminating fungal DNA are potential factors involved. However, detection of fungal DNA by highly sensitive specific PCR assays in the absence of demonstration of fungal elements in tissue suggests that PCR results should be interpreted in the context of the histopathology and clinical findings.

BackgroundKingella kingae is the second most common pathogen causing paediatric arthritis and is described to be the causative bacteria in some paediatric osteomyelitis. Its microbiological detection is particularly difficult due to its slow growing. To our best knowledge this is the first case description of osteomyelitis pubis caused by this microorganism.Case presentationWe report the unusual case of pubic osteomyelitis with soft tissue abcess caused by Kingella kingae in an adult patient of 66 years with a history of end-stage renal disease and breast carcinoma. Diagnosis was based on imaging and the microorganism was isolated from Computed Tomography-guided aspiration of synovial fluid. The infection resolved completely after twelve weeks of treatment with oral amoxicillin.ConclusionThis case description highlights the importance in osteoarticular infections of systematic inoculation of synovial liquid in BACTEC vials to optimise the detection of causative organisms, which can necessitate specific treatments.