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OBJECTIVE: Analyse the incidence, risk factors, antimicrobial susceptibility profile, and fatality in neonates infected with oxacillin-resistant Staphylococcus spp. (ORS). METHODS: In this retrospective observational descriptive cohort study, the medical records of neonates admitted to the Neonatal Intensive Care Unit (NICU) from January 2015 to June 2022 were analysed. Participants were monitored daily through the National Healthcare Safety Network. RESULTS: Among the 1610 neonates, 193 (12 %) developed ORS infections, primarily in the bloodstream (96.8 %). The incidence of these infections/patient-days decreased by 51.8 % between 2016 (8.3) and 2022 (4). The median age of affected neonates was 17.5 days (IQR:12-28.7). Pre-emptive prescription of fourth-generation cephalosporins (OR=14.36; P<0.01) emerged as a risk factor in the multivariate analysis. Staphylococcus epidermidis was the most prevalent species (60.1 %), with one isolate showing a "susceptible, increased exposure" profile to vancomycin. Additionally, 2 % of pathogens were extensively drug-resistant (XDR). ORS infections were associated with prolonged hospital stays (from 10 to 46 days) and increased mortality (from 10.2 % to 19.2 %). The median time between infection and the fatal outcome was 15 days (IQR:8-40), and Staphylococcus capitis was the most lethal species (26.7 %). CONCLUSIONS: The high incidence of ORS infections was linked to extended hospitalisation and increased mortality, highlighting the complexity of this situation - a "perfect storm." This underscores the urgency of implementing effective interventions for managing and preventing ORS infections in the NICU.

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Brodie's abscess is a manifestation of subacute to chronic osteomyelitis, characterized as intraosseous abscess formation, usually on the metaphysis of the long tubular bones in the lower extremities of male pediatric patients. Clinically, Brodie's abscess presents with atraumatic bone pain of an insidious onset, with absence of systemic findings. Delay in diagnosis is common, as diagnostic imaging, followed by biopsy for culture and histologic examination are generally required to secure a diagnosis of Brodie's abscess. Treatment of Brodie's abscess is non-standardized, and usually consists of surgical debridement and antibacterial therapy. Despite the variability in therapeutic approaches, outcomes of Brodie's abscess treated with surgery and antibiotics are favourable. Herein we report a case of a delayed diagnosis of Brodie's abscess in the upper extremity of an adult female. While she improved with treatment of Brodie's abscess, the case serves to remind clinicians to consider this entity in adult individuals who present with atraumatic bone pain.

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Hip arthroplasties are surgical procedures widely performed all over the world, seeking to return functionality, relieve pain, and improve the quality of life of patients affected by osteoarthritis, femoral neck fractures, osteonecrosis of the femoral head, among other etiologies. Periprosthetic joint infections are one of the most feared complications due to the high associated morbidity and mortality, with a high number of pathogens that may be associated with its etiology. The aim of the present study was to analyze aspects correlated with the occurrence of infection, diagnosis and prevention of periprosthetic joint infections in the hip associated with Staphylococcus aureus after corrective surgery for hip fractures. This is a systematic review of the literature carried out in the databases indexed in the Medical Literature Analysis and Retrieval System Online (MEDLINE) carried out in accordance with the precepts established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Twenty studies that addressed the diagnosis and prevention of periprosthetic joint infections after hip fractures were selected for analysis. It is observed that there is no consensus in the literature on preventive measures for the occurrence of such infectious processes. Among the risk factors for the occurrence and severity of infections by S. aureus after hip arthroplasties, obesity, longer surgical time, older age, immunosuppression, recent use of antibiotics, and multicomorbidities were mentioned. The use of biomarkers for early diagnosis, as well as screening, decolonization, and antibiotic prophylaxis processes are among the preventive procedures proposed in the literature.

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Staphylococci are well-known opportunistic pathogens associated with suppurative diseases in humans and animals. Antimicrobial resistance is an emergent threat to humans and animals worldwide. This study investigated the prevalence of methicillin-resistant Staphylococcus spp. (MRS) in hospitalized horses and contacting personnel (veterinarians and staff), and assessed possible interspecies transmission in a teaching veterinary hospital. Nasal swabs from horses (n = 131) and humans (n = 35) were collected. The microorganisms were identified by traditional biochemical tests and genotypic methods, i.e., PCR, internal transcript spacer PCR (ITS-PCR), and gene sequencing. Staphylococcal species were isolated in 18% (23/131) of the horses, of which 8% (11/131) were S. hyicus, 4 % (5/131) were S. aureus, 4% (5/131) were S. pseudintermedius, and 2% (2/131) were S. schleiferi subsp. coagulans. The mecA gene was detected in an S. pseudintermedius isolate. Staphylococcus spp. was isolated in 40% (14/35) of the human samples, all of which were S. aureus. In four samples of S. aureus, the clonal profile ST398 was identified; among them, a clonal similarity of 98.1% was observed between a horse and a contacting human. This finding supports the need for biosecurity measures to avoid the spread of multidrug-resistant staphylococci in humans and horses.

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Staphylococcus aureus and other staphylococcal species are resident and transient multihost colonizers as well as conditional pathogens. Especially S. aureus represents an excellent model bacterium for the "One Health" concept because of its dynamics at the human-animal interface and versatility with respect to host adaptation. The development of antimicrobial resistance plays another integral part. This overview will focus on studies at the human-animal interface with respect to livestock farming and to companion animals, as well as on staphylococci in wildlife. In this context transmissions of staphylococci and of antimicrobial resistance genes between animals and humans are of particular significance.

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Abstract Hip arthroplasties are surgical procedures widely performed all over the world, seeking to return functionality, relieve pain, and improve the quality of life of patients affected by osteoarthritis, femoral neck fractures, osteonecrosis of the femoral head, among other etiologies. Periprosthetic joint infections are one of the most feared complications due to the high associated morbidity and mortality, with a high number of pathogens that may be associated with its etiology. The aim of the present study was to analyze aspects correlated with the occurrence of infection, diagnosis and prevention of periprosthetic joint infections in the hip associated with Staphylococcus aureus after corrective surgery for hip fractures. This is a systematic review of the literature carried out in the databases indexed in the Medical Literature Analysis and Retrieval System Online (MEDLINE) carried out in accordance with the precepts established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Twenty studies that addressed the diagnosis and prevention of periprosthetic joint infections after hip fractures were selected for analysis. It is observed that there is no consensus in the literature on preventive measures for the occurrence of such infectious processes. Among the risk factors for the occurrence and severity of infections by S. aureus after hip arthroplasties, obesity, longer surgical time, older age, immunosuppression, recent use of antibiotics, and multicomorbidities were mentioned. The use of biomarkers for early diagnosis, as well as screening, decolonization, and antibiotic prophylaxis processes are among the preventive procedures proposed in the literature.

Resumo As artroplastias de quadril são procedimentos cirúrgicos largamente realizados em todo o mundo buscando retorno da funcionalidade, alívio da dor e melhora da qualidade de vida dos pacientes acometidos por quadros de osteoartrite, fraturas de colo de fêmur e osteonecrose da cabeça femoral, dentre outras etiologias. As infecções articulares periprotéticas são uma das complicações mais temidas pela elevada morbimortalidade associada, com elevado número de patógenos que podem estar associados à sua etiologia. O objetivo do presente estudo foi analisar aspectos correlacionados à ocorrência da infecção, diagnóstico e prevenção de infecções articulares periprotéticas no quadril associadas a Staphylococcus aureus após cirurgia corretiva de fraturas de quadril. Trata-se de uma revisão sistemática de literatura realizada nas bases de dados indexadas na Medical Literature Analysis and Retrieval System Online (MEDLINE, na sigla em inglês) realizada de acordo com os preceitos estabelecidos pela metodologia Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA, na sigla em inglês). Foram selecionados para análise 20 estudos que abordavam o diagnóstico e prevenção de infecções articulares periprotéticas após fraturas de quadril. Observa-se que não há consenso na literatura sobre medidas preventivas para ocorrência de tais processo infecciosos. Dentre os fatores de risco para ocorrência e gravidade das infecções por S. aureus após artroplastias de quadril foram citados obesidade, maior tempo cirúrgico, maior idade, quadros de imunossupressão, uso recente de antibióticos e multicomorbidades. O uso de bio-marcadores para diagnóstico precoce, bem como processos de triagem, descolonização e antibioticoprofilaxia estão entre os procedimentos preventivos propostos na literatura.

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Staphylococcus epidermidis is a major nosocomial pathogen with a remarkable ability to adhere to the surfaces of indwelling medical devices and form biofilms. Unlike other nosocomial pathogens, the interaction of S. epidermidis with host factors has not been the focus of substantial research. This study aimed to assess the alterations in the antibiotic susceptibility and biofilm formation ability of S. epidermidis in the presence of host serum factors. S. epidermidis strain RP62A was cultured in a laboratory culture medium with or without human serum/plasma, and changes in antibiotic susceptibility, biofilm formation, and gene expression were evaluated. The data obtained revealed that exposure to host serum factors increased the susceptibility of S. epidermidis to glycopeptide antibiotics and was also detrimental to biofilm formation. Gene expression analysis revealed downregulation of both dltA and fmtC genes shortly after human serum/plasma exposure. The importance of transferrin-mediated iron sequestration as a host anti-biofilm strategy against S. epidermidis was also emphasized. We have demonstrated that serum factors play a pivotal role as part of the host's anti-infective strategy against S. epidermidis infections, highlighting the importance of incorporating such factors during in vitro studies with this pathogen.

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Job's syndrome, or autosomal dominant hyperimmunoglobulin E syndrome (AD-HIES, STAT3-Dominant Negative), is a rare inborn error of immunity (IEI) with multi-organ involvement and long-life post-infective damage. Longitudinal registries are of primary importance in improving our knowledge of the natural history and management of these rare disorders. This study aimed to describe the natural history of 30 Italian patients with AD-HIES recorded in the Italian network for primary immunodeficiency (IPINet) registry. This study shows the incidence of manifestations present at the time of diagnosis versus those that arose during follow up at a referral center for IEI. The mean time of diagnostic delay was 13.7 years, while the age of disease onset was < 12 months in 66.7% of patients. Respiratory complications, namely bronchiectasis and pneumatoceles, were present at diagnosis in 46.7% and 43.3% of patients, respectively. Antimicrobial prophylaxis resulted in a decrease in the incidence of pneumonia from 76.7% to 46.7%. At the time of diagnosis, skin involvement was present in 93.3% of the patients, including eczema (80.8%) and abscesses (66.7%). At the time of follow-up, under therapy, the prevalence of complications decreased: eczema and skin abscesses reduced to 63.3% and 56.7%, respectively. Antifungal prophylaxis decreased the incidence of mucocutaneous candidiasis from 70% to 56.7%. During the SARS-CoV-2 pandemic, seven patients developed COVID-19. Survival analyses showed that 27 out of 30 patients survived, while three patients died at ages of 28, 39, and 46 years as a consequence of lung bleeding, lymphoma, and sepsis, respectively. Analysis of a cumulative follow-up period of 278.7 patient-years showed that early diagnosis, adequate management at expertise centers for IEI, prophylactic antibiotics, and antifungal therapy improve outcomes and can positively influence the life expectancy of patients.

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THERAPEUTIC IMPLICATIONS OF THE MICROBIOLOGY OF SEVERE SKIN INFECTIONS. Bacterial necrotizing dermo-hypodermatitis (BNHD) is a serious infection that can be life-threatening. They require urgent surgical management, treatment of organ failure, and early and appropriate antibiotic therapy. The microbiology of BNHD is often polymicrobial and varies according to the location of the infection, the local ecology and the risk factors for resistant bacteria. In this context, probabilistic antibiotic therapy should be early, intravenous, bactericidal, broad-spectrum, and should thus cover both Gram-positive and Gram-negative bacteria and anaerobes. The addition of a systematic anti-toxin treatment also seems reasonable. The use of high doses and therapeutic monitoring of antibiotics are also important elements to consider. Finally, de-escalation of the antibiotic spectrum according to the microbiological result is essential.

IMPLICATIONS THÉRAPEUTIQUES DE LA MICROBIOLOGIE DES INFECTIONS CUTANÉES GRAVES Les dermohypodermites bactériennes nécrosantes (DHBN) sont des infections graves qui peuvent mettre en jeu le pronostic vital. Elles nécessitent à la fois une prise en charge chirurgicale urgente, le traitement des défaillances d'organes mais aussi une antibiothérapie précoce et adaptée. La microbiologie des DHBN est souvent polymicrobienne et varie en fonction de la localisation de l'infection, de l'écologie locale et des facteurs de risque de bactéries résistantes. Dans ce contexte, l'antibiothérapie probabiliste doit être précoce, intraveineuse, bactéricide, à large spectre et doit ainsi couvrir à la fois les bactéries à Gram positif, à Gram négatif et les anaérobies. L'ajout d'un traitement antitoxinique systématique semble également raisonnable. Par ailleurs, l'utilisation de doses élevées et une surveillance thérapeutique des antibiotiques sont également des éléments importants à privilégier. Enfin, une désescalade du spectre antibiotique adapté au résultat microbiologique est indispensable.

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Chemical and enzymatic in vivo degradation of antimicrobial peptides represents a major challenge for their therapeutic use to treat bacterial infections. In this work, anionic polysaccharides were investigated for their ability to increase the chemical stability and achieve sustained release of such peptides. The investigated formulations comprised a combination of antimicrobial peptides (vancomycin (VAN) and daptomycin (DAP)) and anionic polysaccharides (xanthan gum (XA), hyaluronic acid (HA), propylene glycol alginate (PGA) and alginic acid (ALG)). VAN dissolved in buffer of pH 7.4 and incubated at 37 °C showed first order degradation kinetics with a reaction rate constant kobs of 5.5 × 10-2 day-1 corresponding with a half-life of 13.9 days. However, once VAN was present in a XA, HA or PGA-based hydrogel, kobs decreased to (2.1-2.3) × 10-2 day-1 while kobs was not affected in an alginate hydrogel and a dextran solution (5.4 × 10-2 and 4.4 × 10-2 day-1). Under the same conditions, XA and PGA also effectively decreased kobs for DAP (5.6 × 10-2 day-1), whereas ALG had no effect and HA even increased the degradation rate. These results demonstrate that the investigated polysaccharides (except ALG for both peptides and HA for DAP) slowed down the degradation of VAN and DAP. DSC analysis was used to investigate on polysaccharide ability to bind water molecules. Rheological analysis highlighted that the polysaccharides containing VAN displayed an increase in G' of their formulations, pointing that the peptides interaction act as crosslinker of the polymer chains. The obtained results suggest that the mechanism of stabilization of VAN and DAP against hydrolytic degradation is conferred by electrostatic interactions between the ionizable amine groups of the drugs and the anionic carboxylate groups of the polysaccharides. This, in turn, results in a close proximity of the drugs to the polysaccharide chain, where the water molecules have a lower mobility and, therefore, a lower thermodynamic activity.

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Pyomyositis is a deep muscle infection of bacterial origin and subacute, which can evolve with multiple intramuscular abscesses. Despite being characterized as an affection of tropical zones, its incidence in temperate zones has been increasing due to immunosuppression factors, such as infection by the human immunodeficiency virus (HIV) and some types of immunosuppressive treatments. Even though it has been known for over a century, it is a rare and potentially serious condition that can lead to septic shock and death. This is a case report of a descriptive nature, which found the relevance of knowledge about this condition for an early diagnosis, enabling positive prognostic repercussions.

A piomiosite é uma infecção muscular profunda, de origem bacteriana e caráter subagudo, que pode evoluir com abcessos intramusculares múltiplos. Apesar de ser caracterizada como uma afecção de zonas tropicais, sua incidência em zonas temperadas vem aumentando por fatores de imunossupressão, como a infecção pelo vírus da imunodeficiência humana (HIV) e alguns tipos de tratamentos imunossupressivos. Mesmo sendo conhecida há mais de um século, é uma condição rara e potencialmente grave, podendo levar ao choque séptico e óbito. Trata-se de um relato de caso de caráter descritivo, que constatou a relevância do conhecimento desta afecção para um diagnóstico precoce, possibilitando repercussões prognósticas positivas.

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BACKGROUND: Staphylococcus lugdunensis has been described as a pathogen of increasing importance in prosthetic joint infections (PJI). Our aim was to describe the clinical presentation of PJI caused by S. lugdunensis, and to correlate the biofilm-forming ability of the bacterial isolates to clinical outcome. METHOD: S. lugdunensis isolates from PJI episodes during 2015-2019 were included and analysed for biofilm formation using a microtiter plate assay. Medical records from the corresponding patients were reviewed. RESULTS: We identified 36 patients with PJI caused by S. lugdunensis during the study period. Early postoperative PJIs were most frequent (n = 20, 56%). Surgical intervention was performed in a majority of the patients (n = 33, 92%), and the dominating type of antibiotic treatment was a combination of rifampicin and ciprofloxacin (n = 27, 75%). The treatment success-rate was 81% (n = 29). All isolates causing PJI were able to form biofilm in vitro. Biofilm formation was significantly stronger in isolates causing relapsing vs non-relapsing PJI (mean OD550 3.1 ± 0.23 vs 1.14 ± 0.73 p = .001) and strong biofilm formation was also associated with late acute hematogenic PJI (mean OD550 1.8 ± 0.93 vs. 0.93 ± 0.81, p = .01). CONCLUSION: Strong biofilm production in S. lugdunensis isolates was associated with relapse in PJI.

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INTRODUCCIÓN: La piomiositis es una infección bacteriana agudasubaguda del músculo esquelético. OBJETIVO: Estimar la incidencia de piomiositis en pacientes internados, describir e identificar factores de riesgo para bacteriemia y hospitalización, y evaluar diferencias entre Staphylococccus aureus sensible y resistente a meticilina (SASM y SARM). PACIENTES Y MÉTODOS: Estudio descriptivo, retrospectivo, observacional, con pacientes de 1 mes a 18 años de edad, internados entre el 1 de enero de 2008 y 31 de diciembre de 2018. Variables: sexo, edad, hacinamiento en el hogar, existencia de lesión previa, estacionalidad, localización anatómica e imágenes, antibioterapia previa, estadio clínico, parámetros de laboratorio, cultivos y antibiograma, días de tratamiento intravenoso (IV), de internación, de fiebre y bacteriemia. RESULTADOS: Se incluyeron 188 pacientes. Incidencia: 38,9 casos / 10.000 admisiones (IC95 % 33,7 - 44,9). Días de internación y tratamiento IV: 11 (RQ 8-15 y RQ 8-14, respectivamente). El desarrollo de bacteriemia se asoció a PCR elevada (p = 0,03) y fiebre prolongada (p < 0,001). No hubo diferencias en la evolución y parámetros de laboratorio entre SASM y SARM. La leucocitosis (p = 0,004), neutrofilia (p = 0,005) y bacteriemia (p = 0,001) se asociaron a mayor estadía hospitalaria. CONCLUSIONES: Este estudio recaba la experiencia de más de 10 años de niños internados con diagnóstico de piomiositis y proporciona información sobre sus características. Se describen parámetros asociados a bacteriemia y estadía hospitalaria.

BACKGROUND: Pyomyositis is an acute-subacute bacterial infection of skeletal muscle. AIM: To estimate the incidence of pyomyositis in hospitalized patients, describe and identify risk factors for bacteremia and hospitalization, and evaluate differences between MSSA and MRSA. METHODS: Descriptive, retrospective, observational study with patients aged 1 month to 18 years hospitalized between January, 1, 2008 and December 1, 2018. Variables: sex, age, home overcrowding, previous injury, seasonality, anatomical location and images, previous antibiotherapy, clinical stage, laboratory, cultures and antibiogram, days of intravenous (IV) treatment, hospitalization, fever and bacteremia. RESULTS: 188 patients were included. Incidence: 38.9 cases/10,000 admissions (95% CI 33.7 - 44.9). Days of hospitalization and IV treatment: 11 (RQ 8-15 and RQ 8-14, respectively). The development of bacteremia was associated with elevated CRP (p = 0.03) and prolonged fever (p < 0.001). There were no differences in the evolution and laboratory parameters between MSSA and MRSA. Leukocytosis (p = 0.004), neutrophilia (p = 0.005), and bacteremia (p = 0.001) were associated with a longer hospital stay. CONCLUSIONS: This study collects the experience of more than 10 years of hospitalized children diagnosed with pyomyositis and provides information on its characteristics. Parameters associated with bacteremia and hospital stay are described.

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As antibiotic resistance is nowadays one of the important challenges, efforts are crucial for the discovery of novel antibacterial drugs. This study aimed to evaluate antimicrobial/anticancerous activities of halophilic bacilli from the human microbiota. A spore-forming halotolerant bacterium with antibacterial effect against Staphylococcus aureus was isolated from healthy human feces. The antibacterial protein components of the extracted supernatant were identified by SDS-PAGE and zymography. The MALDI-TOF, GC mass, and FTIR analyses were used for peptide and lipopeptide identification, respectively. The stability, toxicity, and anticancerous effects were investigated using MTT and Flow cytometry methods. According to the molecular analysis, the strain was identified as Bacillus tequilensis and showed potential probiotic properties, such as bile and acid resistance, as well as eukaryotic cell uptake. SDS-PAGE and zymography showed that 15 and 10-kDa fragments had antibacterial effects. The MALDI-TOF mass analysis indicated that the 15-kDa fragment was L1 ribosomal protein, which was the first report of the RpL1 in bacilli. GC-mass and FTIR analyses confirmed the lipopeptide nature of the 10-kDa fragment. Both the extracted fractions (precipitation or "P" and chloroform or "C" fractions) were stable at < 100 °C for 10 min, and their antibacterial effects were preserved for more than 6 months. Despite its non-toxicity, the P fraction had anticancer activities against MCF7 cells. The anticancer and antibacterial properties of B. tequilensis, along with its non-toxicity and stability, have made it a potential candidate for studying the beneficial probiotic properties for humans and drug production.

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Crossing of interspecies barriers by microorganisms is observed. In recent years, Staphylococcus pseudintermedius-a species formerly thought to be animal-has also been isolated from human clinical materials. Many virulence factors are responsible for the colonization, which is the first step an infection, of the new host organism. We analyzed the factors influencing this colonization as well as susceptibility to antibiotics in fourteen S. pseudintermedius strains isolated from clinical cases from humans and animals. The occurrence of genes responsible for binding elastin, fibronectin, and fibrinogen and some phenotypic features, although different between strains, is comparable in both groups. However, the animal isolates had more genes coding for virulence factors. All isolates tested had the exfoliating toxin gene and the leukotoxin determining genes, but only the human strains had enterotoxin genes. The assessment of antibiotic resistance of strains of both groups indicates their broad resistance to antibiotics commonly used in veterinary medicine. Antibiotic resistance was more common among animal isolates. The multilocus sequence typing analysis of the studied strains was performed. The results indicated a large diversity of the S. pseudintermedius population in both studied groups of strains. Equipped with important virulence factors, they showed the ability to infect animals and humans. The clonal differentiation of the methicillin-susceptible strains and the multidrug resistance of the strains of both studied groups should be emphasized. The considerable genetic diversity of strains from a limited geographical area indicates the processes of change taking place within this species. Thus, careful observation of the ongoing process of variation is necessary, as they may lead to the selection of S. pseudintermedius, which will pose a significant threat to humans.

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Staphylococcus aureus bacteremia is common and associated with fatality rates approximating 25%. We provide a brief overview of S. aureus bacteremia from a clinical and microbiological lens and review the relevant evidence and literature gaps in its management. Using a case-based approach, evidence and clinical judgement are meshed to highlight and justify the 5 core interventions that ought to be performed for all cases of S. aureus bacteremia: 1) appropriate anti-staphylococcal therapy, 2) screening echocardiography, 3) assessment for metastatic phenomena and source control, 4) decision on duration of antimicrobial therapy, and 5) Infectious Diseases consultation.

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IgA-dominant infection-related glomerulonephritis (IgA-IRGN) is a unique form of infection-associated glomerulonephritis. The main causative organism is staphylococcus. Although IgA-IRGN is rare in children, the prevalence is gradually increasing, and the prognosis is poor in children with immunodeficiency and mucocutaneous barrier dysfunction. The clinical manifestations are varying degrees of hematuria, proteinuria, acute kidney injury and hypocomplementemia. The renal pathology is similar to postinfectious glomerulonephritis, therefore differential diagnosis is challenging. The paper reviews the current research progress of IgA-IRGN to improve the pediatrician's understanding of IgA-IRGN in children and avoid misdiagnosis.

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ABSTRACT Molecular imaging markers can be used to differentiate between infection and aseptic inflammation, determine the severity of infection, and monitor treatment responses. One of these markers is ubiquicidin(29-41) (UBI), a cationic peptide fragment that binds to the bacterial membrane wall and is labeled with gallium-68 (68Ga), a positron emitter radioisotope. The use of UBI in positron emission tomography (PET)/computed tomography (CT) for improved detection of lesions has been receiving considerable attention recently. Herein, we report the first case of 68Ga-UBI PET/CT performed in Brazil. The patient was a 39-year-old woman referred for a scan to confirm a clinical suspicion of chronic osteomyelitis of her fractured left tibia. PET images revealed radiotracer uptake near the posterior contour of the tibial fracture focus and the fixation plate, in the soft tissue around the distal half of the tibia, and in the non-consolidated fracture of the left distal fibula. Surgery for local cleaning was performed, and culture of a specimen collected from the surgical site confirmed the presence of Staphylococcus aureus. In the present case, 68Ga-UBI PET/CT, a non-invasive imaging modality, identified the infection foci in vivo, indicating its potential for clinical use.

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Objectives: The inability of the host immune system to defeat Staphylococcus aureus is due to various secreted virulent factors such as leukocidins, superantigens, and hemolysins, which interrupt the function of immune components. Alpha-hemolysin is one of the most studied cytolysins due to its pronounced effect on developing staphylococcal infections. Alpha-hemolysin-neutralizing antibodies are among the best candidates for blocking the toxin activity and preventing S. aureus pathogenesis. Materials and Methods: A human single-chain variable fragment (scFv) phage display library was biopanned against alpha-hemolysin. The selected phage clones were assessed based on their binding ability to alpha-hemolysin. The binding specificity and affinity of two scFvs (designated SP192 and SP220) to alpha-hemolysin were determined by enzyme-linked immunosorbent assay. Furthermore, the neutralizing activity of SP192 and SP220 was examined by concurrent incubation of rabbit red blood cells (RBCs) with alpha-hemolysin and scFvs. Results: SP192 and SP220 showed significant binding to alpha-hemolysin compared with the control proteins, including bovine serum albumin, human adiponectin, and toxic shock syndrome toxin-1. Besides, both scFvs showed high-affinity binding to alpha-hemolysin in the nanomolar range (Kaff: 0.9 and 0.7 nM-1, respectively), leading to marked inhibition of alpha-hemolysin-mediated lysis of rabbit RBCs (73% and 84% inhibition; respectively). Conclusion: SP192 and SP220 scFvs can potentially be used as alpha-hemolysin-neutralizing agents in conjunction with conventional antibiotics to combat S. aureus infections.