Abstract. Rickettsial infections represent a major cause of non-malarial febrile illnesses among the residents of Southeast Asia and returned travelers from that region. There are several challenges in recognition, diagnosis, and management of rickettsioses endemic to Southeast Asia. This review focuses on the prevalent rickettsial infections, namely, murine typhus (Rickettsia typhi), scrub typhus (Orientia tsutsugamushi), and members of spotted fever group rickettsiae. Information on epidemiology and regional variance in the prevalence of rickettsial infections is analyzed. Clinical characteristics of main groups of rickettsioses, unusual presentations, and common pitfalls in diagnosis are further discussed. In particular, relevant epidemiologic and clinical aspects on emerging spotted fever group rickettsiae in the region, such as Rickettsia honei, R. felis, R. japonica, and R. helvetica, are presented. Furthermore, challenges in laboratory diagnosis and management aspects of rickettsial infections unique to Southeast Asia are discussed, and data on emerging resistance to antimicrobial drugs and treatment/prevention options are also reviewed.

Pulmonary infections by Sporothrix spp. manifest radiologically as cavitary or non-cavitary disease depending on whether the infection is primary pulmonary or multifocal sporotrichosis. Despite current guidelines, the optimal management for pulmonary sporotrichosis remains unclear. In order to clarify this, we present two cases of pulmonary sporotrichosis, as well as the results of a comprehensive literature review of treatment outcomes based on clinico-radiological presentation patterns of the disease. A literature search of all case reports in English language over the last 50 years (1960-2010) was conducted. Data on patient characteristics, risk factors, clinico-radiological patterns, treatment modalities and outcomes were collected and analyzed. A total of 86 cases were identified, i.e., 64 (74.4%) primary pulmonary and 22 (25.6%) multifocal sporotrichosis. Radiologically, primary pulmonary disease was commonly characterized by cavity formation which was lacking in multifocal infections (P = 0.0001). Immunosuppressant use was more common in multifocal sporotrichosis (P = 0.0001), while hemoptysis was more common in primary pulmonary form (P = 0.01). No other differences in patient characteristics or risk factors were noted. Extra-pulmonary multifocal sporotrichosis most commonly involved skin (81.8%) and joints (45.4%). For patients with cavitary primary pulmonary sporotrichosis, outcomes from medical therapy alone were inferior to surgical intervention (P = 0.02). However, for both primary pulmonary and multifocal sporotrichosis with non-cavitary disease, medical therapy alone provided good outcomes. Only 12 (16.7%) cases were treated with itraconazole. Treatment of pulmonary sporotrichosis should be guided by the clinico-radiological patterns of presentation. Medical therapy alone is likely sufficient for non-cavitary disease while early surgery should be considered for cavitary primary pulmonary sporotrichosis. The experience in treating cavitary disease with itraconazole alone is limited and further data are required.

BACKGROUND For severe cutaneous adverse reactions (SCARs) associated with multiple antibiotics dosed concurrently, clinical causality is challenging and diagnostic approaches are limited, leading to constricted future antibiotic choices. OBJECTIVE To examine the combined utility of in vivo and ex vivo diagnostic approaches at assigning drug causality in a cohort of patients with antibiotic-associated (AA)-SCARs. METHODS Patients with AA-SCARs were prospectively recruited between April 2015 and February 2017. In vivo testing (patch testing or delayed intradermal testing) was performed to the implicated antibiotic(s) at the highest nonirritating concentration and read at 24 hours through 1 week. Ex vivo testing used patient peripheral blood mononuclear cells (PBMCs) stimulated with a range of pharmacologically relevant concentrations of implicated antibiotics to measure dose-dependent IFN-g release from CD4D and CD8D T cells via an enzyme-linked immunoSpot assay. RESULTS In 19 patients with AA-SCARs, combined in vivo and ex vivo testing assigned antibiotic causality in 15 (79%) patients. Ten patients (53%) with AA-SCARs were positive on IFN-g release enzyme-linked immunoSpot assay, with an overall reported sensitivity of 52% (95% CI, 29-76) and specificity of100% (95% CI, 79-100), with improved sensitivity noted in acute (within 1 day to 6 weeks after SCAR onset) testing (75%) and in patients with higher phenotypic scores (59%). There was increased use of narrow-spectrum beta-lactams and antibiotics from within the implicated class following testing in patients with a positive ex vivo or in vivo test result. CONCLUSIONS We demonstrate the potential utility of combined in vivo and ex vivo testing in patients with AA-SCARs to assign drug causality with high specificity.

Objectives: To determine the nature, prevalence and description accuracy of recorded antibiotic allergy labels (AALs) in a cohort of general medical inpatients, and to assess the feasibility of an oral antibiotic re‐challenge study. Design: Multicentre cross‐sectional study. Setting and participants: All patients admitted to the general medical units of Austin Health and Alfred Health, 18 May – 5 June 2015. Main outcome measures: Baseline demographics, medical and allergy history, infection diagnoses and antibiotic prescribing data for general medical inpatients were collected. A questionnaire was administered to clarify AAL history, followed by correlation of responses with electronic and admissions record descriptions. A hypothetical oral re‐challenge in a supervised setting was offered to patients with low risk allergy phenotypes (non‐immediate reaction, non‐severe cutaneous adverse reaction, or unknown reaction more than 10 years ago). Results: Of the 453 inpatients, 107 (24%) had an AAL (median age, 82 years; interquartile range, 74–87 years); 160 individual AALs were recorded, and there was a mismatch in AAL description between recording platforms in 25% of cases. Most patients with an AAL were women (64%; P < 0.001), and more presented with concurrent immunosuppression than those without an AAL (23% v 8%; P < 0.001). β‐Lactam penicillins were employed less frequently in patients with an AAL (16% v 35%; P = 0.02), while ceftriaxone (32% v 20%; P = 0.02) and fluoroquinolones (6% v 2%; P = 0.04) were used more often. Fifty‐four per cent of patients with AALs were willing to undergo oral re‐challenge, of whom 48% had a low risk allergy phenotype. Conclusions: AAL prevalence in general medical inpatients was 24%, and was associated with excessive use of broad spectrum antibiotics. Allergies in a large proportion of patients with AALs were incorrectly documented, and were non‐immune‐mediated and potentially amenable to oral re‐challenge. A direct oral re‐challenge study in carefully selected patients with low risk allergy phenotypes appears feasible.

Severe cutaneous adverse reactions (SCARs) encompass a heterogeneous group of delayed hypersensitivity reactions, which are most frequently caused by drugs. Our understanding of several aspects of SCAR syndromes has evolved considerably over the previous decade. This review explores evolving knowledge on the immunopathogenic mechanisms, pharmacogenomic associations, in-vivo and ex-vivo diagnostics for causality assessment and medication cross-reactivity data related to SCAR syndromes. Given the rarity and severity of these diseases, multidisciplinary collaboration through large international, national and/or multicentre networks to collect prospective data on patients with SCAR syndromes should be prioritized. This will further enhance a systematised framework for translating epidemiological, clinical, and immunopathogenetic advances into preventive efforts and improved outcomes for patients.

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Highlights Angiotensin converting enzyme (ACE) genotypes may influence COVID-19 mortality. II genotype frequency was significantly associated with decreased mortality. Association between increased mortality and DD genotype frequency was not detected.