Quantification of cefuroxime and flucloxacillin in synovial tissue and bone using ultra-performance convergence chromatography-tandem mass spectrometry.

After a revision surgery, approximately 1-2 % of patients will develop a periprosthetic joint infection (PJI). During the revision surgery, the infected prosthesis is removed, a debridement is performed and a new or temporary spacer is placed. Additionally, patients are treated with antibiotics during and after the surgery. Adequate exposure of the administered antibiotic to the pathogen is of crucial importance during the treatment of any infection. Inadequately low concentrations are associated with an increase in antibiotic resistance, antibiotic related side effects, treatment failures and prolonged infections. While high concentrations may lead to serious adverse events and potential lasting damage. Despite the importance of optimal dosing, there is a lack of knowledge with respect to the correlation between the plasma concentrations and target site concentrations of the antibiotics. Two of the commonly administered antimicrobial agents during the arthroplasty exchange are cefuroxime and flucloxacillin. Therefore, an accurate, specific, and sensitive quantification method is required in order to assess pharmacokinetics of cefuroxime and flucloxacillin in synovial tissue and bone. The aim of this study is to develop and validate a quantification method for the measurement of cefuroxime and flucloxacillin in human synovial tissue and bone using the UPC2-MS/MS conform Food and Drug Administration guidelines. The method was found linear for both compounds in both matrices (r2 > 0.990) from 1 µg/g to 20 µg/g, except for cefuroxime in bone, which was validated from 1 µg/g to 15 µg/g. We developed and validated a quantification method for cefuroxime and flucloxacillin in synovial tissue and bone using a simple sample preparation and a short analysis run time of 5.0 min, which has been already successfully applied in a clinical study. To our knowledge, no methods have been described earlier for the simultaneous quantification of cefuroxime and flucloxacillin in synovial tissue and bone.

Pyroglutamate acidosis 2023. A review of 100 cases.

This review concerns the rare, acquired, usually iatrogenic, high-anion-gap metabolic acidosis, pyroglutamic acidosis. Pyroglutamate is a derivative of the amino acid glutamate, and is an intermediate in the 'glutathione cycle', by which glutathione is continuously synthesized and broken down. The vast majority of pyroglutamic acidosis cases occur in patients on regular, therapeutic doses of paracetamol. In about a third of cases, flucloxacillin is co-prescribed. In addition, the patients are almost always seriously unwell in other ways, typically with under-nourishment of some form. Paracetamol, with underlying disorders, conspires to divert the glutathione cycle, leading to the overproduction of pyroglutamate. Hypokalaemia is seen in about a third of cases. Once the diagnosis is suspected, it is simple to stop the paracetamol and change the antibiotic (if flucloxacillin is present), pending biochemistry. N-acetyl-cysteine can be given, but while the biochemical justification is compelling, the clinical evidence base is anecdotal.

Effect of Microdoses of Incisional Antibiotics on the Rate of Surgical Site Infections in Skin Cancer Surgery: A Randomized Clinical Trial.

Importance: Surgical site infections (SSIs) represent a costly and preventable complication of cutaneous surgery. However, there is a paucity of randomized clinical trials investigating antibiotic prophylaxis for reducing SSIs in skin cancer surgery, and evidence-based guidelines are lacking. Incisional antibiotics have been shown to reduce the rate of SSIs before Mohs micrographic surgery, but this represents a small subset of skin cancer surgery. Objective: To determine whether microdosed incisional antibiotics reduce the rate of SSIs before skin cancer surgery. Design, Setting, and Participants: In this double-blind, controlled, parallel-design randomized clinical trial, adult patients presenting to a high-volume skin cancer treatment center in Auckland, New Zealand, for any form of skin cancer surgery over 6 months from February to July 2019 were included. Patient presentations were randomized to one of 3 treatment arms. Data were analyzed from October 2021 to February 2022. Interventions: Patients received an incision site injection of buffered local anesthetic alone (control), buffered local anesthetic with microdosed flucloxacillin (500 µg/mL), or buffered local anesthetic with microdosed clindamycin (500 µg/mL). Main Outcomes and Measures: The primary end point was the rate of postoperative SSI (calculated as number of lesions with SSI per total number of lesions in the group), defined as a standardized postoperative wound infection score of 5 or more. Results: A total of 681 patients (721 total presentations; 1133 total lesions) returned for postoperative assessments and were analyzed. Of these, 413 (60.6%) were male, and the mean (SD) age was 70.4 (14.8) years. Based on treatment received, the proportion of lesions exhibiting a postoperative wound infection score of 5 or greater was 5.7% (22 of 388) in the control arm, 5.3% (17 of 323) in the flucloxacillin arm, and 2.1% (9 of 422) in the clindamycin arm (P = .01 for clindamycin vs control). Findings were similar after adjusting for baseline differences among arms. Compared with lesions in the control arm (31 of 388 [8.0%]), significantly fewer lesions in the clindamycin arm (9 of 422 [2.1%]; P < .001) and flucloxacillin (13 of 323 [4.0%]; P = .03) arms required postoperative systemic antibiotics. Conclusions and Relevance: This study evaluated the use of incisional antibiotics for SSI prophylaxis in general skin cancer surgery and compared the efficacy of flucloxacillin vs clindamycin relative to control in cutaneous surgery. The significant reduction in SSI with locally applied microdosed incisional clindamycin provides robust evidence to inform treatment guidelines in this area, which are currently lacking. Trial Registration: anzctr.org.au Identifier: ACTRN12616000364471.

Identification of flucloxacillin-modified hepatocellular proteins: implications in flucloxacillin-induced liver injury.

Flucloxacillin is a ß-lactam antibiotic associated with a high incidence of drug-induced liver injury. Although expression of HLA-B*57:01 is associated with increased susceptibility, little is known of the pathological mechanisms involved in the induction of the clinical phenotype. Irreversible protein modification is suspected to drive the reaction through the provision of flucloxacillin-modified peptides that are presented to T-cells by the protein encoded by the risk allele. In this study, we have shown that flucloxacillin binds to multiple proteins within human primary hepatocytes, including major hepatocellular proteins (hemoglobin and albumin) and mitochondrial proteins. Inhibition of membrane transporters multidrug resistance-associated protein 2 (MRP2) and P-glycoprotein (P-gp) appeared to reduce the levels of covalent binding. A diverse range of proteins with different functions was found to be targeted by flucloxacillin, including adaptor proteins (14-3-3), proteins with catalytic activities (liver carboxylesterase 1, tRNA-splicing endonuclease subunit Sen2, All-trans-retinol dehydrogenase ADH1B, Glutamate dehydrogenase 1 mitochondrial, Carbamoyl-phosphate synthase [ammonia] mitochondrial), and transporters (hemoglobin, albumin, and UTP-glucose-1-phosphate uridylyltransferase). These flucloxacillin-modified intracellular proteins could provide a potential source of neoantigens for HLA-B*57:01 presentation by hepatocytes. More importantly, covalent binding to critical cellular proteins could be the molecular initiating events that lead to flucloxacillin-induced cholestasis Data are available via ProteomeXchange with identifier PXD038581.

Mycotic Pseudoaneurysm of the Aortic Arch.

A 59 year-old male presents with fever and left parasternal pain. Past medical history included arterial hypertension, dyslipidemia, smoking, obesity. His clinical exam was unremarkable. Both C-reactive protein and leucocytes were elevated. Chest computed tomography (CT) demonstrated a 18mm saccular pseudoaneurysm of the aortic arch with extensive adjacent densification and adenopathy (Figure 1 and 2). Methicillin-sensible Staphylococcus aureus was isolated from blood cultures. A transesophageal echocardiogram excluded endocarditis. Control Angio-CT after seven days showed a contained rupture and increase in diameter of the pseudoaneurysm. He underwent emergent surgery with circulatory arrest and anterograde cerebral perfusion; extensive resection of the pseudoaneurysmal aorta was performed, with reconstruction of the aortic arch using autologous pericardium, without implantation of foreign or synthetic material (Figure 3 and 4). He completed 4 weeks of Flucloxacillin IV, having been discharged under oral antibiotics.

[A case of pyroglutamic metabolic acidosis after cotreatment by flucloxacillin and paracetamol]. / Un cas d'acidose métabolique pyroglutamique sur comédication par flucloxacilline et paracétamol.

We report on the case of a 73-year-old man, who was referred to our emergency department for confusion and dyspnea. He had been under a treatment of flucloxacillin for six weeks because of a possible methicillin-susceptible Staphylococcus aureus (MSSA) endocarditis that was complicated by an acute late infection of a knee prosthesis. The laboratory work-up revealed a metabolic acidosis with a high anion gap. After exclusion of the other explanations, we retained a pyroglutamic metabolic acidosis due to concomitant intake of paracetamol and flucloxacillin, favoured by several risk factors. This diagnosis was confirmed by an organic acid dosage in the urine. After discontinuation of the drugs and a treatment with N-acetylcysteine, the evolution was favourable with correction of the metabolic acidosis and the confusional state.

Nous rapportons le cas d'un homme de 73 ans, sous traitement de flucloxacilline depuis 6 semaines pour une possible endocardite à Staphylococcus aureus sensible à la méticilline (SASM) compliquée d'une infection aiguë tardive d'une prothèse de genou. Il est adressé à notre service d'urgences pour un état confusionnel et une dyspnée. Le bilan met en évidence une acidose métabolique à trou anionique élevé. Après exclusion des différentes étiologies, nous retenons une acidose métabolique pyroglutamique d'origine médicamenteuse sur prise concomitante de paracétamol et flucloxacilline, favorisée par plusieurs facteurs précipitants. Ce diagnostic est confirmé par un dosage d'acide organique dans les urines. Après arrêt des médicaments incriminés et traitement par N-acétylcystéine, l'évolution est favorable avec correction de l'acidose métabolique et de l'état confusionnel.

Flucloxacillin-induced liver injury in elderly patient.

Flucloxacillin is a penicillin antibiotic used as first-line treatment for soft tissue infections caused by Staphylococcus aureus It is used frequently in the elderly and is an established cause of cholestatic liver injury. Risk factors for cholestasis include prolonged duration of treatment, female sex and older age. Elderly patients are also more likely to suffer from comorbidities and polypharmacy, which increases the incidence of drug-induced liver injury and hospitalisation, which in turn can lead to irreversible deterioration in functional baseline. Our case report aims to raise awareness of flucloxacillin-induced liver injury in elderly patients and to encourage the use of alternative treatments and/or limited duration. We advocate for further research into individualised treatments and new diagnostic techniques in patients with painless jaundice based on their genotype.

[Non-Necrotizing Acute Dermo-Hypodermal Infections: Erysipela and Infectious Cellulitis]. / Dermo-Hipodermites Bacterianas Agudas Não Necrotizantes: Erisipela e Celulite Infeciosa.

Non-necrotizing acute dermo-hypodermal infections are infectious processes that include erysipela and infectious cellulitis, and are mainly caused by group A ß-haemolytic streptococcus. The lower limbs are affected in more than 80% of cases and the risk factors are disruption of cutaneous barrier, lymphoedema and obesity. Diagnosis is clinical and in a typical setting we observe an acute inflammatory plaque with fever, lymphangitis, adenopathy and leucocytosis. Bacteriology is usually not helpful because of low sensitivity or delayed positivity. In case of atypical presentations, erysipela must be distinguished from necrotizing fasciitis and acute vein thrombosis. Flucloxacillin and cefradine remain the first line of treatment. Recurrence is the main complication, so correct treatment of the risk factors is crucial.

As dermo-hipodermites bacterianas agudas não necrotizantes são processos infeciosos que incluem a erisipela e a celulite infeciosa, e são geralmente causadas por estreptococos ß­hemolíticos do grupo A. Em mais de 80% dos casos situam-se nos membros inferiores e são fatores predisponentes a existência de solução de continuidade na pele, o linfedema crónico e a obesidade. O seu diagnóstico é essencialmente clínico e o quadro típico baseia-se na presença de placa inflamatória associada a febre, linfangite, adenopatia e leucocitose. Os exames bacteriológicos têm baixa sensibilidade ou positividade tardia. Nos casos atípicos é importante o diagnóstico diferencial com a fasceíte necrotizante e a trombose venosa profunda. A flucloxacilina ou a cefradina são os fármacos de primeira linha. A recidiva constitui a complicação mais frequente, sendo fundamental o correto tratamento dos fatores de risco.

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung.

The effective prescription of antibiotics for the bacterial biofilms present within the lungs of individuals with cystic fibrosis (CF) is limited by a poor correlation between antibiotic susceptibility testing (AST) results using standard diagnostic methods (e.g., broth microdilution, disk diffusion, or Etest) and clinical outcomes after antibiotic treatment. Attempts to improve AST by the use of off-the-shelf biofilm growth platforms show little improvement in results. The limited ability of in vitro biofilm systems to mimic the physicochemical environment of the CF lung and, therefore bacterial physiology and biofilm architecture, also acts as a brake on the discovery of novel therapies for CF infection. Here, we present a protocol to perform AST of CF pathogens grown as mature, in vivo-like biofilms in an ex vivo CF lung model comprised of pig bronchiolar tissue and synthetic CF sputum (ex vivo pig lung, EVPL). Several in vitro assays exist for biofilm susceptibility testing, using either standard laboratory medium or various formulations of synthetic CF sputum in microtiter plates. Both growth medium and biofilm substrate (polystyrene plate vs. bronchiolar tissue) are likely to affect biofilm antibiotic tolerance. We show enhanced tolerance of clinical Pseudomonas aeruginosa and Staphylococcus aureus isolates in the ex vivo model; the effects of antibiotic treatment of biofilms is not correlated with the minimum inhibitory concentration (MIC) in standard microdilution assays or a sensitive/resistant classification in disk diffusion assays. The ex vivo platform could be used for bespoke biofilm AST of patient samples and as an enhanced testing platform for potential antibiofilm agents during pharmaceutical research and development. Improving the prescription or acceleration of antibiofilm drug discovery through the use of more in vivo-like testing platforms could drastically improve health outcomes for individuals with CF, as well as reduce the costs of clinical treatment and discovery research.

Flucloxacillin-Induced Hepatotoxicity - Association with HLA-B*5701.

Drug-induced liver injury (DILI) to flucloxacillin is rare and is classified as idiosyncratic, as it is dependent on individual susceptibility, unpredictable, and dose-independent. The authors present the case of a 74 - year - old man with a history of monoclonal gammopathy under investigation and alcoholic habits of 24 g/day, with asthenia, anorexia, nausea, abdominal discomfort, and fever with three days of evolution. He was treated with two courses of antibiotic therapy with flucloxacillin to erysipelas previously (3 months and 2 weeks before admission). Lab tests showed serum AST levels of 349 U/L, ALT 646 U/L, alkaline phosphatase 302 U/L, GGT 652 U/L, total bilirubin 3.3 mg/dL and direct bilirubin 2.72 mg/dL. Infectious, autoimmune, and metabolic causes were ruled out. Magnetic resonance cholangiopancreatography showed normal results. Liver biopsy showed mild multifocal (predominantly microvesicular) steatosis; marked changes in the centrilobular areas (sinusoidal dilatation, marked congestion, hemorrhage, and multifocal hepatocyte collapse); expansion of the portal areas with the formation of bridges; proliferated bile ducts and inflammatory infiltrate of variable density, predominantly mononuclear type. The HLA-B*5701 screening test was positive. Hepatic biochemical tests remain abnormal with a significative increase in total bilirubin, which reached levels of 24.1 mg/dL, with the development of jaundice, pruritus, and choluria. DILI was assumed, and the patient was treated with ursodeoxycholic acid. There was favorable evolution, without evidence of blood coagulation dysfunction or encephalopathy. The analytic normalization was, however, slow, with evolution to chronicity. The authors present this case to remind the possibility of moderate/severe drug-induced liver injury to flucloxacillin, an antibiotic commonly used in clinical practice and association with the HLA-B * 5701 allele reported in the literature.

Successful liver transplantation for drug-induced vanishing bile duct syndrome.

Drug-induced cholestasis has a wide range of clinical presentations, and in a small number of patients, it can progress to severe ductopenia. A 63-year-old woman was referred to our department with progressive cholestasis and hyperbilirubinaemia following a course of flucloxacillin. Despite the comprehensive laboratory, imaging and genetic investigations, no other cause for the cholestasis was demonstrated. Sequential liver biopsies confirmed the development of vanishing bile duct syndrome. She developed significant cachexia and pruritus that did not respond to medical therapy, and hence she was listed for liver transplantation. She underwent liver transplantation 6 months after the initial drug-induced injury. She has remained well with good graft function at 1-year follow-up. The case highlights an extreme form of drug-induced ductopenia and underscores the need for meticulous hepatology input and consideration of liver transplantation in some patients.

Flucloxacillin-Induced Hepatotoxicity - Association with HLA-B*5701

SUMMARY Drug-induced liver injury (DILI) to flucloxacillin is rare and is classified as idiosyncratic, as it is dependent on individual susceptibility, unpredictable, and dose-independent. The authors present the case of a 74 - year - old man with a history of monoclonal gammopathy under investigation and alcoholic habits of 24 g/day, with asthenia, anorexia, nausea, abdominal discomfort, and fever with three days of evolution. He was treated with two courses of antibiotic therapy with flucloxacillin to erysipelas previously (3 months and 2 weeks before admission). Lab tests showed serum AST levels of 349 U/L, ALT 646 U/L, alkaline phosphatase 302 U/L, GGT 652 U/L, total bilirubin 3.3 mg/dL and direct bilirubin 2.72 mg/dL. Infectious, autoimmune, and metabolic causes were ruled out. Magnetic resonance cholangiopancreatography showed normal results. Liver biopsy showed mild multifocal (predominantly microvesicular) steatosis; marked changes in the centrilobular areas (sinusoidal dilatation, marked congestion, hemorrhage, and multifocal hepatocyte collapse); expansion of the portal areas with the formation of bridges; proliferated bile ducts and inflammatory infiltrate of variable density, predominantly mononuclear type. The HLA-B*5701 screening test was positive. Hepatic biochemical tests remain abnormal with a significative increase in total bilirubin, which reached levels of 24.1 mg/dL, with the development of jaundice, pruritus, and choluria. DILI was assumed, and the patient was treated with ursodeoxycholic acid. There was favorable evolution, without evidence of blood coagulation dysfunction or encephalopathy. The analytic normalization was, however, slow, with evolution to chronicity. The authors present this case to remind the possibility of moderate/severe drug-induced liver injury to flucloxacillin, an antibiotic commonly used in clinical practice and association with the HLA-B * 5701 allele reported in the literature.

RESUMO A hepatotoxicidade à flucloxacilina é rara e classifica-se como idiossincrática, uma vez que é dependente da suscetibilidade individual, não expectável e independente da dose. Apresentamos o caso de um homem, 74 anos, antecedentes de gamapatia monoclonal e hábitos alcoólicos de 24 g/dia, com quadro de astenia, anorexia, náuseas, desconforto abdominal e febrícula com três dias de evolução. Referência a dois ciclos de antibioterapia com flucloxacilina por erisipela (três meses e duas semanas antes da admissão). Analiticamente com AST 349 U/L, ALT 646 U/L, FA 302 U/L, GGT 652 U/L, bilirrubina total 3,3 mg/dL, bilirrubina direta 2,72 mg/dL. Excluídas etiologias infecciosa, autoimune, metabólica, bem como patologia das vias biliares por colangio-RM. Biópsia hepática mostrou esteatose multifocal ligeira (predominantemente microvesicular); alterações acentuadas nas áreas centrolobulares (dilatação sinusoidal, congestão acentuada, hemorragia e colapso multifocal de hepatócitos); expansão das áreas portais com constituição de pontes; ductos biliares proliferados e infiltrado inflamatório de densidade variável, predominantemente de tipo mononucleado. Tipagem de HLA-B*5701 positiva. Agravamento analítico atingindo bilirrubina total 24,1 mg/dL, com desenvolvimento de icterícia, prurido e colúria. Admitida a hepatotoxicidade, iniciou terapêutica com ácido ursodesoxicólico. Verificou-se evolução favorável, sem evidência de coagulopatia ou encefalopatia. A normalização analítica foi, no entanto, lenta, com evolução para cronicidade. Os autores apresentam este caso para alertar para a possibilidade de hepatotoxicidade moderada a grave à flucloxacilina, antibiótico de uso comum na prática clínica e associação com o alelo HLA-B*5701 relatada na literatura.

Alterations in the HLA-B*57:01 Immunopeptidome by Flucloxacillin and Immunogenicity of Drug-Haptenated Peptides.

Neoantigen formation due to the interaction of drug molecules with human leukocyte antigen (HLA)-peptide complexes can lead to severe hypersensitivity reactions. Flucloxacillin (FLX), a ß-lactam antibiotic for narrow-spectrum gram-positive bacterial infections, has been associated with severe immune-mediated drug-induced liver injury caused by an influx of T-lymphocytes targeting liver cells potentially recognizing drug-haptenated peptides in the context of HLA-B*57:01. To identify immunopeptidome changes that could lead to drug-driven immunogenicity, we used mass spectrometry to characterize the proteome and immunopeptidome of B-lymphoblastoid cells solely expressing HLA-B*57:01 as MHC-I molecules. Selected drug-conjugated peptides identified in these cells were synthesized and tested for their immunogenicity in HLA-B*57:01-transgenic mice. T cell responses were evaluated in vitro by immune assays. The immunopeptidome of FLX-treated cells was more diverse than that of untreated cells, enriched with peptides containing carboxy-terminal tryptophan and FLX-haptenated lysine residues on peptides. Selected FLX-modified peptides with drug on P4 and P6 induced drug-specific CD8+ T cells in vivo. FLX was also found directly linked to the HLA K146 that could interfere with KIR-3DL or peptide interactions. These studies identify a novel effect of antibiotics to alter anchor residue frequencies in HLA-presented peptides which may impact drug-induced inflammation. Covalent FLX-modified lysines on peptides mapped drug-specific immunogenicity primarily at P4 and P6 suggesting these peptide sites as drivers of off-target adverse reactions mediated by FLX. FLX modifications on HLA-B*57:01-exposed lysines may also impact interactions with KIR or TCR and subsequent NK and T cell function.

Valor do ecocardiograma na Endocardite Infecciosa associada aos dispositivos cardíacos implantáveis / Use of echocardiography in Infectious Endocarditis associated with implantable cardiac devices

Nas últimas décadas, o aumento das indicações para dispositivos cardíacos eletrônicos implantáveis tem sido acompanhado pela elevação dos casos de complicações relacionadas ao seu uso, dentre elas a endocardite infecciosa. Apesar dos avanços diagnósticos e terapêuticos da doença, esta mantém elevada morbimortalidade. Os casos relacionados aos dispositivos apresentam importantes limitações referentes aos critérios e aos métodos diagnósticos que implicam na tomada de decisão terapêutica sobre retirada do dispositivo, com risco de morte e outras complicações. Ainda assim, o ecocardiograma mantém um grande valor no diagnóstico da endocardite infecciosa relacionada a dispositivos cardíacos e de suas complicações. O entendimento das limitações e dos desafios acerca do diagnóstico reforça a necessidade de mais estudos sobre do tema. O presente artigo visa descrever a epidemiologia, a microbiologia, os fatores de risco, a patogenia, o diagnóstico e o tratamento da endocardite infecciosa associada aos dispositivos cardíacos eletrônicos implantáveis, visando demonstrar, principalmente, o valor dos exames de imagem na abordagem dessa condição clínica, com ênfase nos achados ao ecocardiograma.

In recent decades, the increase in indications for implantable electronic cardiac devices has been accompanied by an increase in cases of complications related to their use, including infectious endocarditis. Despite the diagnostic and therapeutic advances of the disease, it maintains high morbidity and mortality. The cases related to the devices have important limitations regarding the criteria and diagnostic methods that imply in making a therapeutic decision about removing the device, with risk of death and other complications. Still, echocardiography remains of great value in the diagnosis of infective endocarditis related to cardiac devices and their complications. Understanding the limitations and challenges regarding diagnosis reinforces the need for further studies on the topic. This article aims to describe the epidemiology, microbiology, risk factors, pathogenesis, diagnosis and treatment of infective endocarditis associated with implantable electronic cardiac devices, aiming to demonstrate, mainly, the value of imaging tests in addressing this clinical condition , with emphasis on echocardiogram findings.

An Under-Recognised Cause of Iatrogenic, Severe Metabolic Acidosis

Case Pyroglutamic acidosis is an uncommonly diagnosed but important cause of a high anion gap metabolic acidosis. Our case report concerns an elderly male admitted to the Intensive Care Unit (ICU) following the acute onset of coma which developed during treatment of a prosthetic joint infection. A diagnosis of pyroglutamic acidosis was ultimately made and later confirmed with laboratory testing. Blood gas analysis revealed a profound high anion gap metabolic acidosis. Treatment Treatment included withdrawal of the precipitating medications, N-acetylcysteine and sodium bicarbonate. Discussion This case highlights an unusual cause of severe metabolic acidosis caused by commonly used medications and readily reversible if recognised. This is of particular relevance in elderly, frail patients as incorrect alternate diagnoses may result in decisions which incorrectly limit critical care therapies.

Large paraspinal abscess as a complication of infliximab therapy in Crohn's disease.

We report a 36-year-old man who developed a large epidural and paraspinal abscess as a complication of infliximab therapy being used for underlying Crohn's disease. Cultures of the collection grew methicillin-susceptible Staphylococcus aureus, and treatment consisted of abscess drainage, prolonged intravenous and oral flucloxacillin and temporary withholding of his infliximab. While infection-related complications are well described with infliximab therapy, this is the first description of a large paraspinal abscess with epidural extension.

Optimization of the empirical antibiotic choice during the treatment of acute prosthetic joint infections: a retrospective analysis of 91 patients.

Background and purpose - The preferred treatment of an acute prosthetic joint infection (PJI) is debridement, antibiotics, irrigation and retention of the prosthesis (DAIR). The antibiotic treatment consists of an empirical and targeted phase. In the empirical phase, intravenous antibiotics are started after surgery before micro-organisms are determined in microbiological cultures. Which empirical antibiotic is used differs between hospitals, partly reflecting geographic differences in susceptibility spectrums. We investigated whether flucloxacillin should remain the antibiotic of choice in our hospital for empiric treatment of acute PJI with DAIR. Patients and methods - We retrospectively analyzed 91 patients treated for PJI with DAIR between 2012 and 2016. The susceptibility of micro-organisms was determined in multiple cultures of periprosthetic tissue and synovial fluid for 3 antibiotics: amoxicillin/clavulanic acid, cefazolin, and flucloxacillin. Results - Positive microbiological cultures from 68 patients were analyzed. Staphylococcus aureus was the predominant pathogen, cultured in half of the patients. In one-third of patients more than 1 micro-organism was found. On a patient level, the data showed that 65% were responsive to flucloxacillin, 76% to amoxicillin/clavulanic acid, and 79% to cefazolin. Interpretation - Flucloxacillin appeared to be a suboptimal choice in our patient population treated with DAIR. We therefore changed our practice to cefazolin as the preferred antibiotic in the empirical treatment of acute PJI with DAIR.

Lesson of the month 1: A rare adverse reaction between flucloxacillin and paracetamol.

Flucloxacillin, a beta-lactam antibiotic, is a commonly prescribed antibiotic for the treatment of infections caused by staphylococci and streptococci, most notably Staphylococcus aureus Paracetamol is one of the most dispensed medications by NHS England and is used for the treatment of fever and pain.1 However most doctors are unaware that concurrent use of these drugs can cause a potentially fatal drug interaction due to pyroglutamic acidosis (PGA), also known as 5-oxoprolinaemia. PGA is a rare cause of raised anion gap metabolic acidosis due to disruption of the γ-glutamyl cycle. We report the case of a patient with multiple comorbidities who developed PGA due to coadministration of paracetamol and flucloxacillin.

Conservative treatment of non-aneurysmal infectious aortitis: a case report and review of the literature.

BACKGROUND:  Non-aneurysmal infectious aortitis is a rare clinical entity with most often lethal complications when surgical intervention is delayed. OBJECTIVES:  This report describes the case of a non-aneurysmal infectious aortitis complicated with a penetrating aortic ulcer in an elderly woman, caused by a methicillin-sensitive Staphylococcus aureus. Surgery was deemed contra-indicated and treatment was limited to the administration of intravenous vancomycin (2 grams daily), followed by flucloxacillin (6 times 2 grams daily). She remains well after one year. METHODS: The Internet databases Medline and Embase were searched. Articles were selected based on relevanceof abstract, article type and impact of the journal. RESULTS:  A literature review addresses current insights in the pathogenesis, diagnosis, and treatment of non-aneurysmal infectious aortitis.