In vitro activity of cefiderocol and other newly approved antimicrobials against multi-drug resistant Gram-negative pathogens recovered in intensive care units in Spain and Portugal.

OBJECTIVE: The antimicrobial resistance is a significant public health threat, particularly for healthcare-associated infections caused by carbapenem-resistant Gram-negative pathogens which are increasingly reported worldwide. The aim of this study was to provide data on the in vitro antimicrobial activity of cefiderocol and that of commercially available comparator antibiotics against a defined collection of recent clinical multi-drug resistant (MDR) microorganisms, including carbapenem resistant Gram-negative bacteria collected from different regions in Spain and Portugal. METHODS: A total of 477 clinical isolates of Enterobacterales, Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia were prospectively (n=265) and retrospectively (n=212) included (2016-2019). Susceptibility testing was performed using standard broad microdilution and results were interpreted using CLSI-2021 and EUCAST-2021 criteria. RESULTS: Overall, cefiderocol showed a good activity against Enterobacterales isolates, being 99.5% susceptible by CLSI and 94.5% by EUCAST criteria. It also demonstrated excellent activity against P. aeruginosa and S. maltophilia isolates, all being susceptible to this compound considering CLSI breakpoints. Regarding A. baumannii (n=64), only one isolate was resistant to cefiderocol. CONCLUSIONS: Our results are in agreement with other studies performed outside Spain and Portugal highlighting its excellent activity against MDR gram-negative bacteria. Cefiderocol is a therapeutic alternative to those available for the treatment of infections caused by these MDR bacteria.

Are GES carbapenemases underdiagnosed? An allelic discrimination assay for their accurate detection and differentiation.

GES (Guiana Extended Spectrum) carbapenemases belong to "minor class A carbapenemases" and its prevalence could be underestimated due to the lack of specific tests. The aim of this study was to develop an easy PCR method to differentiate between GES ß-lactamases with or without carbapenemase activity, based on an allelic discrimination system of SNPs that encode E104K and G170S mutations, without need of sequencing. Two pair of primers and Affinity Plus probes, labeled with different fluorophores; FAM/IBFQ and YAK/IBFQ, were designed for each one of the SNPs. This allelic discrimination assay allows to detect in real time the presence of all type of GES- ß-lactamases, being able to differentiate between carbapenemases and extended-spectrum ß-lactamase (ESBL), through a quick PCR test that avoid costly sequencing approaches and could help to decrease the current underdiagnosis of minor carbapenemases that scape of phenotypic screenings.

[Repetition of microbiological tests in suspect of SARS-CoV-2 infection: utility of a score based on clinical probability]. / Repetición de las pruebas microbiológicas en la sospecha de la infección por SARS-CoV-2: utilidad de un score basado en la probabilidad clínica.

OBJECTIVE: The diagnosis of SARS-CoV-2 infection presents some limitations. RT-PCR in nasopharyngeal swabs is considered the gold standard for the diagnosis, although it can have false negative results. We aimed to analyze the accuracy of repeating nasopharyngeal swabs based on different clinical probabilities. METHODS: Retrospective observational study of the first patients admitted to a two COVID Internal Medicine wards at the University Hospital Marqués de Valdecilla, Santander, from March to April 2020. RT-PCR targering E, N, RdRP and ORFab1 genes and antibody tests detecting IgG. RESULTS: A total of 145 hospitalized patients with suspected SARS-Cov2 infection were admitted and in 98 (67.5%) diagnosis was confirmed. The independent predictive variables for SARS-CoV-2 infection were: epidemiological contact, clinical presentation as pneumonia, absence of pneumonia in the last year, onset of symptoms > 7 days, two or more of the following symptoms -dyspnea, cough or fever- and serum lactate dehydrogenase levels >350 U/L (p<0.05). A score based on these variables yielded an AUC-ROC of 0.89 (CI95%, 0.831-0.946; p<0.001). The accuracy of the first nasopharyngeal swabs was 54.9%. Repeating nasopharyngeal swabs two or three times allows to detect an additional 16% of positive cases. The overall accuracy of successive RT-PCR tests in patients with low pre-test probability was <5%. CONCLUSIONS: We have defined a pre-test probability score based on epidemiological and clinical data with a high accuracy for diagnosis of SARS-CoV-2. Repeating nasopharyngeal swabs avoids sampling errors, but only in medium of high probability pre-test clinical scenarios.

[Spontaneous bacterial peritonitis caused by Listeria monocytogenes: eight case reports (1992-2017) and literature review]. / Peritonitis bacteriana espontánea por Listeria monocytogenes: presentación de ocho casos (1992- 2017) y revisión de la literatura.

OBJECTIVE: Spontaneous bacterial peritonitis (SBP) is a frequent and severe entity in patients with cirrhosis or ascites due to other causes. However, Listeria monocytogenes is a microorganism that has been scarcely identified as a causative agent of SBP. METHODS: In this study, a descriptive analysis of cases of L. monocytogenes SBP was carried out in our center for 26 years (1992-2017). RESULTS: A total of eight patients were diagnosed, with an average age of 58 years, with no differences in sex distribution and all of them were community acquired cases. Half of the patients had underlying liver disease, two of them active malignancies; one was undergoing continuous ambulatory peritoneal dialysis and the last one with hypertensive heart disease. Six (75%) of the patients received a third-generation cephalosporin as empirical treatment. The clinical course was favorable after receiving directed antibiotic treatment in five (62.5%) of the patients. However, three of them, under the age of 59, died. Serotyping of L. monocytogenes isolates revealed that half of them were serovar 4, two 1 / 2a and the remaining one 1 / 2c. All strains were susceptible to ampicillin, meropenem, erythromycin and cotrimoxazole. CONCLUSIONS: We conclude by emphasizing the importance of taking this etiology into account in patients with underlying liver disease and with clinical or laboratory data suggesting SBP, mainly due to the need for specific antibiotic treatment different from conventionally empirically used.