Dynamics of the MRSA Population in A Chilean Hospital: A Phylogenomic Analysis (2000-2016).

The global dissemination of methicillin-resistant Staphylococcus aureus (MRSA) is associated with the emergence and establishment of clones in specific geographic areas. The Chilean-Cordobes clone (ChC) (ST5-SCC mec I) has been the predominant MRSA clone in Chile since its first description in 1998, despite the report of other emerging MRSA clones in the last years. Here, we characterize the evolutionary history of MRSA from 2000 to 2016 in a Chilean tertiary healthcare center using phylogenomic analyses. We sequenced 469 MRSA isolates collected between 2000-2016 in a tertiary healthcare center in Chile. We evaluated the temporal trends of the circulating clones and performed a phylogenomic reconstruction to characterize the clonal dynamics. We found a significant increase in the diversity and richness of sequence types (STs; Spearman r=0.8748, p<0.0001) with a Shannon diversity index increasing from 0.221 in the year 2000 to 1.33 in 2016. The temporal trend analysis revealed that in the period 2000-2003 most of the isolates (94.2%; n=98) belonged to the ChC clone. However, since then, the frequency of the ChC clone has decreased over time, accounting for 52% of the collection in the 2013-2016 period. This decline was accompanied by the rise of two emerging MRSA lineages, ST105-SCC mec II and ST72-SCC mec VI. In conclusion, the ChC clone remains the most frequent MRSA lineage in Chile. However, this lineage is gradually being replaced by several emerging clones, the most important of which is clone ST105-SCC mec II. To the best of our knowledge, this is the largest study of MRSA clonal dynamics performed in South America. Importance: Methicillin-resistant Staphylococcus aureus (MRSA) is a major public health pathogen that disseminates through the emergence of successful dominant clones in specific geographic regions. Knowledge of the dissemination and molecular epidemiology of MRSA in Latin America is scarce and is largely based on small studies or classical typing techniques with several limitations to depict an accurate description of their genomic landscape. We used whole-genome sequencing to study 469 MRSA isolates collected between 2000-2016 in Chile to provide the largest and most detailed study of clonal dynamics of MRSA carried out in South America to date. We found a significant increase in the diversity of MRSA clones circulating over the 17-year study period. Additionally, we describe the emergence of two novel clones (ST105-SCCmecII and ST72-SCCmecVI), which have been gradually increasing their frequency over time. Our results drastically improve our understanding of the dissemination and update our knowledge about MRSA in Latin America.

Clinical and Epidemiological Characteristics of the First Month of the Covid-19 Pandemic in Chile

IntroductionUnderstanding the clinical course and outcomes of patients with Covid-19 in underrepresented populations like Latin America is paramount. In this study, we report the clinical characteristics of Covid-19 in Chile, with a focus on subjects requiring hospitalization during the initial phases of the SARS-CoV-2 pandemic. MethodsThis is a single center study including all consecutive patients diagnosed with Covid-19 during the first month of the pandemic. Demographics, clinical characteristics and laboratory data were collected within 24 hours of admission. The primary outcome was a composite of ICU admission or all-cause, in-hospital mortality. ResultsDuring the first month of the pandemic, 381 patients were confirmed as positive for SARS-CoV-2 by molecular testing; 88 (23.1%) of them eventually required hospitalization. Median age of the cohort was 39 years (IQR 31-49). Overall mortality was 0.7% and 18 (3.7%) out of the 88 subjects who required hospitalization either died and/or required ICU. Increased body mass index (BMI), C-reactive protein levels (CRP) and the SaTO2/FiO2 index on admission were independently associated with a higher risk of ICU care or death. DiscussionThe lower mortality observed in our prospective cohort during the first month of SARS-Cov-2 pandemic was lower than previously reported. This finding could be due to a lower threshold for admission, a healthcare system not yet overburdened and a younger population, among other factors. BMI, CRP on admission were strong predictors for ICU care or all-cause, in-hospital mortality. Our data provide important information regarding the clinical course of Covid-19 in Latin America.

Intraosseous Neurothekeoma of the Hand in a 16-year-old Boy.

Soft-tissue tumors are rare in the pediatric population. First described in 1969 as myxoma of the nerve sheath, the neurothekeoma is a benign tumor lesion with presumable origin in the nerve sheath. It occurs mainly in female children and presents as a mass of slow, subcutaneous growth, asymptomatic and without alteration of the local pigmentation. It is predominantly located in the head, neck, and extremities of the upper limbs. This report presents the case of a 16-year-old male with a tumor mass originating from the nerve sheath in the 4 th left metacarpal, intraosseous, and relapsed after previous surgical resection 2 years before this observation. A marginal resection of the tumor mass was performed on the distal region of the fourth metacarpal, followed by curettage of the proximal phalanx and filling with structural autologous bone graft. The patient maintained a favorable postoperative clinical evolution, without local pain or range of motion limitation in his fingers. Radiologically, a progressive trabecular filling of the proximal phalanx of the fourth metacarpal was observed. At 17 months of follow-up, the patient is asymptomatic and shows no signs of relapse. The description of this case serves to increase the familiarity with this rare pathology, and aid its diagnosis and treatment.

Intraosseous Neurothekeoma of the Hand in a 16-year-old Boy / Neurotequeoma intraósseo da mão de um jovem de 16 anos

Abstract Soft-tissue tumors are rare in the pediatric population. First described in 1969 as myxoma of the nerve sheath, the neurothekeoma is a benign tumor lesion with presumable origin in the nerve sheath. It occurs mainly in female children and presents as a mass of slow, subcutaneous growth, asymptomatic and without alteration of the local pigmentation. It is predominantly located in the head, neck, and extremities of the upper limbs. This report presents the case of a 16-year-old male with a tumor mass originating from the nerve sheath in the 4th left metacarpal, intraosseous, and relapsed after previous surgical resection 2 years before this observation. A marginal resection of the tumor mass was performed on the distal region of the fourth metacarpal, followed by curettage of the proximal phalanx and filling with structural autologous bone graft. The patient maintained a favorable postoperative clinical evolution, without local pain or range of motion limitation in his fingers. Radiologically, a progressive trabecular filling of the proximal phalanx of the fourth metacarpal was observed. At 17 months of follow-up, the patient is asymptomatic and shows no signs of relapse. The description of this case serves to increase the familiarity with this rare pathology, and aid its diagnosis and treatment.

Resumo Os tumores dos tecidos moles são raros em idade pediátrica. Descrito pela primeira vez 1969 como um mixoma da bainha nervosa, o neurotequeoma é uma lesão tumoral benigna com presumível origem na bainha nervosa. Ocorre maioritariamente em crianças do sexo feminino e apresenta-se como uma massa de crescimento lento, subcutânea, assintomática e sem alteração da pigmentação local. Localiza-se predominantemente na cabeça, no pescoço, e nas extremidades dos membros superiores. Os autores apresentam um caso clínico de um jovem de 16 anos do sexo masculino com massa tumoral com origem na bainha nervosa no 4º metacarpo esquerdo, intraóssea e recidivada após ressecção cirúrgica 2 anos antes do estudo. Foi feita ressecção marginal da massa tumoral localizada sobre a região distal do quarto metacarpo e curetagem da falange proximal e preenchimento com enxerto ósseo autólogo corticoesponjoso. O paciente apresentou uma evolução clínica pós-operatória favorável, sem queixas álgicas e sem limitações da mobilidade dos dedos da mão. Radiologicamente, foi observado preenchimento trabecular progressivo da falange proximal do quarto metacarpo. Aos 17 meses de seguimento, o paciente se encontra assintomático e não apresenta quaisquer sinais de recidiva. Com a descrição deste caso, os autores pretendem aumentar a familiaridade com essa rara patologia, seu diagnóstico e tratamento.

Current Trends and Variations in the Treatment of Unicameral Bone Cysts of the Humerus: A Survey of EPOS and POSNA Members.

BACKGROUND: A variety of treatment methods have so far been described for unicameral bone cysts (UBC). However, to the best of our knowledge, no particular consensus has yet been reached on when to operatively treat a patient with a humeral UBC. Therefore, members of the European Pediatric Orthopedic Society (EPOS) and Pediatric Orthopedic Society of North America (POSNA) were surveyed to characterize current treatment preferences. METHODS: An online electronic questionnaire was sent out to all registered EPOS and POSNA members. The survey comprised 45 questions related to the diagnosis, treatment, and follow-up characteristics of patients with UBCs of the humerus. Particular questions related to the nonoperative or surgical treatment of pathologic proximal humerus and humeral shaft fractures were also included. RESULTS: In total, 444 participants (132 EPOS and 292 POSNA members) responded, of whom 400 were actively involved in UBC treatment. The preferred diagnostic modalities to confirm the diagnosis of a UBC in the humerus were radiographs (88%), MRI in cases of questionable diagnosis (58%) or CT scan (8%). For painless UBCs 67% prefer no treatment at all except when the fracture risk is deemed high (then 53% recommend surgery); 71% of respondents would treat painful UBCs with surgery. Most common surgical techniques comprise curettage (45%), artificial bone substitutes (37%), corticosteroid injection (29%), or intramedullary stabilization (eg, rodding; 24%).Fractured, nondisplaced and mildly displaced proximal humerus UBCs and mildly displaced pathologic humerus shaft fractures are all preferably treated nonoperatively (94%, 91%, 83%, respectively). Severely displaced pathologic proximal humerus fractures are treated less often conservatively (36%) than surgically (40%), and severely displaced humerus shaft fractures are preferably treated surgically (63%) by intramedullary stabilization (60%). CONCLUSIONS: There is great variation among EPOS and POSNA members with regards to the diagnosis and treatment of UBCs in the humerus. Although some consensus on general treatment principles is seen, specific surgical treatment indications vary.Prospective randomized-controlled studies are needed to evaluate the outcomes of the different surgical approaches compared with nonoperative strategies. LEVEL OF EVIDENCE: Level V-expert opinion.