Nocardiosis: a single-center experience and literature review

INTRODUCTION

Nocardiosis is a rare bacterial infection caused by Nocardia spp. However, an increasing incidence has been described whereby data about epidemiology and prognosis are essential.

METHODS

A retrospective descriptive study was conducted among patients with positive Nocardia spp. culture, from January 2019 to January 2023, at a Terciary Hospital in Portugal.

RESULTS

Nocardiosis was considered in 18 cases with a median age of 63.8-years-old. At least one immunosuppressive cause was identified in 70% of patients. Five patients had Disseminated Nocardiosis (DN). The lung was the most common site of clinical disease (77.8%) and Nocardia was most commonly identified in respiratory tract samples. The most frequently isolated species were Nocardia nova/africana (n = 7) followed by Nocardia cyriacigeorgica (n = 3) and Nocardia pseudobrasiliensis (n = 3). The majority of the patients (94.4%) received antibiotic therapy, of whom as many as 55.6% were treated with monotherapy. The most frequently prescribed antibiotic was trimethoprim-sulfamethoxazole. Selected antimicrobial agents were generally effective, with linezolid and cotrimoxazole (100% Susceptibility [S]) and amikacin (94% S) having the most activity against Nocardia species. The median (IQR) duration of treatment was 24.2 (1‒51.4) weeks for DN; The overall one-year case fatality was 33.3% (n = 6) and was higher in the DN (66.7%). No recurrence was observed.

CONCLUSION

Nocardiosis is an emerging infectious disease with a poor prognosis, particularly in DN. This review offers essential epidemiological insights and underscores the importance of gaining a better understanding of the microbiology of nocardiosis. Such knowledge can lead to the optimization of antimicrobial therapy and, when necessary, guide appropriate surgical interventions to prevent unfavorable outcomes.

Multiplicity of Carbapenemase-Producers Three Years after a KPC-3-Producing K. pneumoniae ST147-K64 Hospital Outbreak

Carbapenem resistance rates increased exponentially between 2014 and 2017 in Portugal (~80%), especially in Klebsiella pneumoniae. We characterized the population of carbapanemase-producing Enterobacterales (CPE) infecting or colonizing hospitalized patients (2017-2018) in a central hospital from northern Portugal, where KPC-3-producing K. pneumoniae capsular type K64 has caused an initial outbreak. We gathered phenotypic (susceptibility data), molecular (population structure, carbapenemase, capsular type) and biochemical (FT-IR) data, together with patients' clinical and epidemiological information. A high diversity of Enterobacterales species, clones (including E. coli ST131) and carbapenemases (mainly KPC-3 but also OXA-48 and VIM) was identified three years after the onset of carbapenemases spread in the hospital studied. ST147-K64 K. pneumoniae, the initial outbreak clone, is still predominant though other high-risk clones have emerged (e.g., ST307, ST392, ST22), some of them with pandrug resistance profiles. Rectal carriage, previous hospitalization or antibiotherapy were presumptively identified as risk factors for subsequent infection. In addition, our previously described Fourier Transform infrared (FT-IR) spectroscopy method typed 94% of K. pneumoniae isolates with high accuracy (98%), and allowed to identify previously circulating clones. This work highlights an increasing diversity of CPE infecting or colonizing patients in Portugal, despite the infection control measures applied, and the need to improve the accuracy and speed of bacterial strain typing, a goal that can be met by simple and cost-effective FT-IR based typing.

Congenital short QT syndrome. A review

Sudden cardiac death in individuals with structurally normal hearts accounts for approximately 20% of sudden cardiac death cases. Patients in this subgroup suffer from what has been named "electrical diseases" which are gradually coming into focus as inherited ion channelopathies, diseases of anchoring proteins or of intracellular calcium regulating proteins. From 1993, the Short QT Syndrome (SQTS) came to our attention, as a new inherited "electrical disease" associated with increased risk of sudden cardiac death and atrial fibrillation. Mutations of Ikr, Iks, Ikl channels cause dysfunctional Iks, Ikr, Ikl channels with an increase in the net outward K current leading to shortening of repolarization. This in turn leads to a shorter QT interval on the ECG and shorter atrial and ventricular refractory periods with increased susceptibility to VF and AF. There seems to be an autosomal dominant mode of inheritance. The clinical profile of SQTS consists of: family history of sudden cardiac death, personal history of palpitations, syncope, dizziness, resuscitated SCD, history of AF and documented VF. It is important to emphasize that SQTS is symptomatic from early age (new-born) to old age. Therefore, it is possible that SQTS accounts for some of the sudden infant death syndrome cases and for some cases of AF, especially lone AF. The only efficient treatment for ventricular arrhythmias is ICD, associated with drugs (Quinidine or Propaphenone) for AF prophylaxis and for reducing the number of ventricular arrhythmic events (and ICD discharges).