Impact of traditional cutaneous scarification on anthrax lesions: A series of cases from Cubal, Angola.

OBJECTIVES: Bacillus anthracis infection is a worldwide zoonosis that affects the most vulnerable population and has a high mortality rate without treatment, especially in non-cutaneous presentations. Cutaneous scarification is still common in some regions of the world for the treatment of certain diseases as part of traditional medicine. We describe a series of cutaneus anthrax from a rural setting in Angola where cutaneus scarification is common. CASE PRESENTATION: This is a retrospective observational study describing a series of cutaneous anthrax cases from Cubal (Angola), many of whom were treated with skin scarification before admission. A total of 26 cases were diagnosed from January 2010 to December 2018. None of the cases were confirmed and eight (30.8%) were probable cases according to the Centers for the Disease Control and Prevention anthrax case definition. The median age was 11 (4.7-30.5) years, 17 (65.4%) had lesions on the head, face, or neck and 15 (57.7%) were treated with cutaneous scarification. Nine (34.6%) patients died. Traditional cutaneous scarification was significantly associated with cutaneous superinfection, respiratory, systemic involvement, and death. CONCLUSION: Our case series points to increased complications and worse outcome of cutaneous anthrax disease if treated with skin scarification.

Validation of MALDI-TOF for the early detection of the ST175 high-risk clone of Pseudomonas aeruginosa in clinical isolates belonging to a Spanish nationwide multicenter study / Validación del MALDI-TOF para la detección precoz del clon de alto riesgo ST175 de Pseudomonas aeruginosa en aislados clínicos pertenecientes a un estudio multicéntrico nacional

Introduction: Pseudomonas aeruginosa causes severe infections, particularly in healthcare settings and immunocompromised patients in whom MDR and XDR isolates are more prevalent. The aim of this study is to validate a method based on MALDI-TOF spectra analysis for early detection of the ST175 high-risk clone (HRC). Methods: The MALDI-TOF spectra of the first 10 P. aeruginosa clinical isolates from each of the 51 participating Spanish hospitals were analyzed (n=506). Resistance profiles were determined by broth microdilution, and clonal epidemiology was assessed by PFGE analysis and multilocus sequence typing (MLST) in a previous study. Results: Among all the isolates, 14.2% were XDR and 26.9% were non-susceptible to meropenem, while rates of resistance to ceftolozane/tazobactam (3.6%) and colistin (5.7%) were low. Up to 41.7% of all XDR isolates belonged to the ST175 clone, and most of them were only susceptible to ceftolozane/tazobactam and colistin. However, most of the resistance to ceftolozane/tazobactam among isolates belonging to this HRC was observed in carbapenemase-producing isolates. A model based on the presence of two MALDI-TOF biomarker peaks at m/z 6911 and 7359 yielded a negative predictive value (NPV) and a positive predictive value (PPV) of 99.8% and 91.9%, respectively, and sensitivity and specificity values of 97.1% and 99.4%, respectively. Conclusions: MALDI-TOF spectra analysis using a model based on the presence of two biomarker peaks proved to maintain high sensitivity and specificity for early detection of the ST175 HRC in a large collection of isolates from all Spanish regions. These data support the use of this model in a clinical setting; however, the consequences of detection of the ST175 HRC, such as choice of empirical antibiotic therapy, must be consistent with local epidemiology and the prevalence of certain resistance patterns of this HRC, such as carbapenemase production, in a given geographical area.(AU)

Introducción: P. aeruginosa causa infecciones graves, particularmente asociadas a cuidados sanitarios y en pacientes inmunodeprimidos, donde los aislamientos MDR o XDR son más frecuentes. El objetivo de este estudio es validar el método basado en el análisis de espectros MALDI-TOF para la detección precoz del clon de alto riesgo ST175. Métodos: Se analizaron los espectros de MALDI-TOF de los primeros 10 aislados clínicos de P. aeruginosa pertenecientes a cada uno de los 51 hospitales españoles participantes (n=506). En un trabajo previo se determinaron los perfiles de resistencia mediante microdilución en caldo y se estableció su relación clonal mediante electroforesis en campo pulsante (PFGE) y multilocus sequence typing (MLST). Resultados: Del total de los aislamientos el 14,2% fueron XDR y el 26,9% resultaron ser no sensibles a meropenem, mientras que la resistencia al ceftolozano-tazobactam (3,6%) y la colistina (5,7%) fue baja. Hasta el 41,7% de todos los aislamientos XDR pertenecieron al clon ST175 y la mayoría de ellos solo resultaron ser sensibles a ceftolozano-tazobactam y a colistina. No obstante, la mayor parte de la resistencia a ceftolozano-tazobactam observada entre los aislados pertenecientes a este clon de alto riesgo se debió a la producción de carbapenemasas. El modelo basado en la presencia de dos picos de biomarcadores MALDI-TOF en m/z 6911 y 7359 obtuvo un valor predictivo negativo y positivo (VPN/VPP) del 99,8/91,9% y valores de sensibilidad y especificidad del 97,1/99,4%, respectivamente. Conclusiones: El análisis de los espectros de MALDI-TOF utilizando el modelo basado en la presencia de dos picos de biomarcadores ha demostrado poseer una alta sensibilidad y especificidad para la detección precoz del clon de alto riesgo ST175 en una gran colección de aislados clínicos representando todo el territorio español.(AU)

Predicting Pseudomonas aeruginosa susceptibility phenotypes from whole genome sequence resistome analysis.

OBJECTIVES: The aim was to develop and validate a Pseudomonas aeruginosa genotypic resistance score, based on analysis of the whole genome sequence resistome, to predict antimicrobial susceptibility phenotypes. METHODS: A scoring system based on the analysis of mutation-driven resistance in 40 chromosomal genes and horizontally acquired resistance (Resfinder) was developed for ceftazidime, ceftolozane/tazobactam, meropenem, ciprofloxacin and tobramycin. Resistance genes/mutations were scored from 0 (no effect) to 1 (EUCAST clinical resistance). One hundred wild-type strains obtained from 51 different hospitals during a 2017 multicentre study were fully sequenced and analysed in order to define a catalogue of natural polymorphisms in the 40 chromosomal resistance genes. The capacity of genotypic score to predict the susceptibility phenotype was tested in 204 isolates randomly selected from the 51 hospitals (four from each hospital). RESULTS: The analysis of the 100 wild-type isolates yielded a catalogue of 455 natural polymorphisms in the 40 genes involved in mutational resistance. However, resistance mutations and high-risk clones (such as ST235) were also documented among a few wild-type isolates. Overall, the capacity of the genotypic score (<0.5) for predicting phenotypic susceptibility (S + I in the case of meropenem) was very high (95-100%). In contrast, the capacity of the genotypic score to predict resistance (≥1) was far more variable depending on the agent. Prediction of meropenem clinical resistance was particularly low (18/39, 46.1%), whereas it classified clinical ceftolozane/tazobactam resistance in 100% (7/7) of cases. DISCUSSION: Although a margin for improvement was evidenced in this proof of concept study, an overall good correlation between the genotypic resistance score and the susceptibility profile was documented. Further refining of the scoring system, automatization and testing of large international cohorts should follow.