Assessment of ventilation rates inside educational buildings in Southwestern Europe: Analysis of implemented strategic measures

The pandemic caused by COVID-19 has highlighted the need to ensure good indoor air quality. Public buildings (educational buildings in particular) have come under the spotlight because students, teachers and staff spend long periods of the day indoors. This study presents a measurement campaign for the assessment of ventilation rate (VR) and ventilation strategies in educational buildings in Southwestern Europe, Portugal and Spain. A representative sample of the teaching spaces of the Azurém Campus (Guimarães, Portugal) and the Fuentenueva Campus (Granada, Spain) have been analyzed. Natural ventilation is the predominant ventilation strategy in these spaces, being the most common strategy in educational buildings in Europe. VR was estimated under different configurations, using the CO2 decay method. Subsequently, the CO2 concentration was estimated according to occupancy and the probability of infection risk was calculated using the Wells-Riley equation. The obtained VR varied between 2.9 and 20.1 air change per hour (ACH) for natural cross ventilation, 2.0 to 5.1 ACH for single-sided ventilation and 1.8 to 3.5 for mechanically ventilated classrooms. Large differences in CO2 concentrations were verified, depending on the analyzed ventilation strategy, ranging from 475 to 3903 ppm for the different scenarios. However, the probability of risk was less than 1% in almost all of the classrooms analyzed. The results obtained from the measurement campaign showed that the selection of an appropriate ventilation strategy can provide sufficient air renewal and maintain a low risk of infection. Ventilation strategies need to be reconsidered as a consequence of the health emergency arising from the COVID-19 pandemic.Antonio J. Aguilar Aguilera and María Luisa de la Hoz Torres wish to thank the support of the Ministerio de Ciencia, Innovación y Universidades of Spain under an FPU grant. This work has been supported by the Consejo General de la Arquitectura T´ecnica (CGATE), the “Junta de Andalucía” (Spain) under project B-TEP-362-UGR18 and the State Research Agency (SRA) of Spain and European Regional Development Funds (ERDF) under project PID2019-108761RB-I00. Funding for open access charge: Universidad de Granada / CBUA

Overexpression of AmpC and Efflux Pumps in Pseudomonas aeruginosa Isolates from Bloodstream Infections: Prevalence and Impact on Resistance in a Spanish Multicenter Study▿

The prevalence and impact of the overexpression of AmpC and efflux pumps were evaluated with a collection of 190 Pseudomonas aeruginosa isolates recovered from bloodstream infections in a 2008 multicenter study (10 hospitals) in Spain. The MICs of a panel of 13 antipseudomonal agents were determined by microdilution, and the expressions of ampC, mexB, mexY, mexD, and mexF were determined by real-time reverse transcription (RT)-PCR. Up to 39% of the isolates overexpressed at least one of the mechanisms. ampC overexpression (24.2%) was the most prevalent mechanism, followed by mexY (13.2%), mexB (12.6%), mexF (4.2%), and mexD (2.2%). The overexpression of mexB plus mexY, documented for 5.3% of the isolates, was the only combination showing a significantly (P = 0.02) higher prevalence than expected from the frequencies of the individual mechanisms (1.6%). Additionally, all imipenem-resistant isolates studied (25 representative isolates) showed inactivating mutations in oprD. Most of the isolates nonsusceptible to piperacillin-tazobactam (96%) and ceftazidime (84%) overexpressed ampC, while mexB (25%) and mexY (29%) overexpressions gained relevance among cefepime-nonsusceptible isolates. Nevertheless, the prevalence of mexY overexpression was highest among tobramycin-nonsusceptible isolates (37%), and that of mexB was highest among meropenem-nonsusceptible isolates (33%). Regarding ciprofloxacin-resistant isolates, besides the expected increased prevalence of efflux pump overexpression, a highly significant link to ampC overexpression was documented for the first time: up to 52% of ciprofloxacin-nonsusceptible isolates overexpressed ampC, sharply contrasting with the 24% documented for the complete collection (P < 0.001). In summary, mutation-driven resistance was frequent in P. aeruginosa isolates from bloodstream infections, whereas metallo-β-lactamases, detected in 2 isolates (1%) producing VIM-2, although with increasing prevalences, were still uncommon