Volatile biomarkers of Gram-positive bacteria of clinical relevance as a tool for infection diagnosis.

AIM: Volatile organic compounds (VOCs) are being studied as potential biomarkers in many infections. Therefore, this study aimed to analyze the volatile profile of three Gram-positive bacteria of clinical relevance to identify potential volatile biomarkers that allow their differentiation. METHODS AND RESULTS: L. monocytogenes, S. aureus, and E. faecalis clinical isolates were inoculated in a thioglycollate medium until grown. Then, VOCs were extracted by solid-phase microextraction, and the data obtained were subjected to multivariate analysis. According to our results, there was a high production of aldehydes in E. faecalis. In the case of alcohols, they only increased in L. monocytogenes, while ketones were produced significantly in all three bacteria, mainly due to acetoin. Acids were produced significantly in E. faecalis and L. monocytogenes. CONCLUSIONS: Potential biomarkers of L. monocytogenes could be 1-butanol and 2-methylbutanoic acid. In the case of E. faecalis, the VOC most related to its presence was nonanal. Lastly, potential biomarkers of S. aureus could be isoamyl butanoate and methionol, although some pyrazines have also been associated with this bacterium. SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of potential biomarkers of these clinically relevant bacteria could open the way for the diagnosis of these infections through the analysis of volatile compounds.

Clinical and Ecological Impact of an Educational Program to Optimize Antibiotic Treatments in Nursing Homes (PROA-SENIOR): A Cluster, Randomized, Controlled Trial and Interrupted Time-Series Analysis.

BACKGROUND: Antimicrobial stewardship programs (ASPs) are recommended in nursing homes (NHs), although data are limited. We aimed to determine the clinical and ecological impact of an ASP for NHs. METHODS: We performed a cluster, randomized, controlled trial and a before-after study with interrupted time-series analyses in 14 NHs for 30 consecutive months from July 2018 to December 2020 in Andalusia, Spain. Seven facilities implemented an ASP with a bundle of 5 educational measures (general ASP) and 7 added 1-to-1 educational interviews (experimental ASP). The primary outcome was the overall use of antimicrobials, calculated monthly as defined daily doses (DDD) per 1000 resident days (DRD). RESULTS: The total mean antimicrobial consumption decreased by 31.2% (-16.72 DRD; P = .045) with respect to the preintervention period; the overall use of quinolones and amoxicillin-clavulanic acid dropped by 52.2% (P = .001) and 42.5% (P = .006), respectively; and the overall prevalence of multidrug-resistant organisms (MDROs) decreased from 24.7% to 17.4% (P = .012). During the intervention period, 12.5 educational interviews per doctor were performed in the experimental ASP group; no differences were found in the total mean antimicrobial use between groups (-14.62 DRD; P = .25). Two unexpected coronavirus disease 2019 waves affected the centers increasing the overall mean use of antimicrobials by 40% (51.56 DRD; P < .0001). CONCLUSIONS: This study suggests that an ASP for NHs appears to be associated with a decrease in total consumption of antimicrobials and prevalence of MDROs. This trial did not find benefits associated with educational interviews, probably due to the coronavirus disease 2019 pandemic. Clinical Trials Registration. NCT03543605.

[The relevance of correct identification and interpretation of susceptibility testing of Aeromonas spp. bacteremia isolates]. / Influencia de la correcta identificación en la interpretación de las pruebas de sensibilidad en aislados de Aeromonas spp. productoras de bacteriemia.

OBJECTIVE: To assess the relevance of correct identification and interpretation of susceptibility testing of Aeromonas spp. bacteremia isolates using newly developed molecular methods in comparison to previous conventional methods. MATERIAL AND METHODS: The study included 22 patients with bacteremia due to Aeromonas hydrophila group, microbiologically characterized using the MicroScan system. Further identification to species level was performed by mass spectrometry, and confirmed by sequencing the rpoB gene. The MIC of imipenem, cefotaxime, piperacillin-tazobactam, ciprofloxacin and cotrimoxazole was studied using a commercial broth microdilution and antibiotic gradient strips with low and high inocula. Detection of carbapenemase production was performed using the modified Hodge test, and was confirmed by amplifying the cphA gene by PCR. RESULTS: A total of 9 (40.9%) isolates were identified as Aeromonas hydrophila, 8 (36.4%) as Aeromonas veronii, and the remaining 5 (22.7%) isolates as Aeromonas caviae. Resistance to beta-lactams according to both the commercial microdilution and MIC gradient strips methods was: 36%-50% to imipenem; 4%-56% to cefotaxime, and 27%-56% to piperacillin/tazobactam. The agreement between results generated by the automated system and the diffusion antibiotic gradient strip was, for all 3 species, 68% for imipenem, 50% to cefotaxime, and 46% to piperacillin/tazobactam. No resistance to cotrimoxazole and ciprofloxacin was found by either of the two methods, although 22.7% of the strains were resistant to nalidixic acid. CONCLUSIONS: It is essential to identify the isolates of Aeromonas spp. at the species level, due to the fact that beta-lactam resistance is species- and method-dependent. The high rate of resistance to beta-lactam and quinolones reduce their application as empiric treatments for invasive infection by Aeromonas ssp.

Ultrasensitive and rapid identification of ESRI developer- and piperacillin/tazobactam-resistant Escherichia coli by the MALDIpiptaz test.

BACKGROUND: The excessive use of piperacillin/tazobactam (P/T) has promoted the emergence of P/T-resistant Enterobacterales. We reported that in Escherichia coli, P/T contributes to the development of extended-spectrum resistance to ß-lactam/ß-lactamase inhibitor (BL/BLI) (ESRI) in isolates that are P/T susceptible but have low-level resistance to BL/BLI. Currently, the detection of P/T resistance relying on conventional methods is time-consuming. To overcome this issue, we developed a cost-effective test based on MALDI-MS technology, called MALDIpiptaz, which aims to detect P/T resistance and ESRI developers in E. coli. METHODS: We used automated Clover MS Data Analysis software to analyse the protein profile spectra obtained by MALDI-MS from a collection of 248 E. coli isolates (91 P/T-resistant, 81 ESRI developers and 76 P/T-susceptible). This software allowed to preprocess all the spectra to build different peak matrices that were analysed by machine learning algorithms. RESULTS: We demonstrated that MALDIpiptaz can efficiently and rapidly (15 min) discriminate between P/T-resistant, ESRI developer and P/T-susceptible isolates and allowed the correct classification between ESRI developers from their isogenic resistance to P/T. CONCLUSION: The combination of excellent performance and cost-effectiveness are all desirable attributes, allowing the MALDIpiptaz test to be a useful tool for the rapid determination of P/T resistance in clinically relevant E. coli isolates.

Impact of the COVID-19 Pandemic on Survival in the Patients With the Intra-Abdominal Infections.

Objective: To analyze the availability and access to the hospital for the patients with intra-abdominal infections (IAIs) by Escherichia coli (E. coli) as a result of the coronavirus disease 2019 (COVID-19) pandemic and the impact of these changes in the diagnosis and their effects on the death of these patients. Methods: Two prospective observational cohorts of the patients with IAI by E. coli were conducted in 2016 (the pre-COVID-19, n = 108) and in 2020 (during the COVID-19, n = 96) at the University Hospital of Seville, Spain. The demographic and clinical variables of the patients were collected and analyzed. The patients were followed-up for 120 days, until the hospital discharge or death. The bivariate and multivariate analyses were performed. Results: Both the cohorts were homogeneous according to age, sex, emergency surgery cause, immunosuppression, neutropenia, acquisition type, and previous intervention. The patients attended during the COVID-19 had significantly higher Charlson comorbidity index and the more McCabe score, required more emergency surgery, had more severe infections with the higher rates of septic shock and sepsis, and the presence of additional care support such as a nasogastric tube. They were diagnosed later; the time intervals between the symptoms onset (SO) to the first medical contact or surgical intervention (SI) and between the first medical contact to the admission or SI were significantly higher. The death rates during the COVID-19 and the pre-COVID-19 were 16.7 and 6.5%, respectively (p = 0.02). Finally, the multivariate analysis in both the cohorts together identified the patients diagnosed during the COVID-19, the longer period from SO to SI, septic shock, and the Charlson comorbidity index as the independent factors associated with death. Conclusion: This study showed the impact of the COVID-19 pandemic on the clinical outcome and death due to IAI with an extension of the time between SO and SI.

Linezolid for therapy of Staphylococcus aureus meningitis: a cohort study of 26 patients.

BACKGROUND: Linezolid has good penetration to the meninges and could be an alternative for treatment of Staphylococcus aureus meningitis. We assessed the efficacy and safety of linezolid therapy for this infection. METHODS: Retrospective multicenter cohort study of 26 adults treated with linezolid, derived from a cohort of 350 cases of S. aureus meningitis diagnosed at 11 university hospitals in Spain (1981-2015). RESULTS: There were 15 males (58%) and mean age was 47.3 years. Meningitis was postoperative in 21 (81%) patients. The infection was nosocomial in 23 (88%) cases, and caused by methicillin-resistant S. aureus in 15 cases and methicillin-susceptible S. aureus in 11. Linezolid was given as empirical therapy in 10 cases, as directed therapy in 10, and due to failure of vancomycin in 6. Monotherapy was given to 16 (62%) patients. Median duration of linezolid therapy was 17 days (IQR 12-22 days) with a daily dose of 1,200 mg in all cases. The clinical response rate to linezolid was 69% (18/26) and microbiological response was observed in 14 of 15 cases evaluated (93%). Overall 30-day mortality was 23% and was directly associated with infection in most cases. When compared with the patients of the cohort, no significant difference in mortality was observed between patients receiving linezolid or vancomycin for therapy of methicillin-resistant S. aureus meningitis (9% vs. 20%; p = .16) nor between patients receiving linezolid or cloxacillin for therapy of methicillin-susceptible S. aureus meningitis (20% vs 14%; p = .68). Adverse events appeared in 14% (3/22) of patients, but linezolid was discontinued in only one patient. CONCLUSIONS: Linezolid appears to be effective and safe for therapy of S. aureus meningitis. Our findings showed that linezolid may be considered an adequate alternative to other antimicrobials in meningitis caused by S. aureus.

A prospective, multicenter case control study of risk factors for acquisition and mortality in Enterobacter species bacteremia.

BACKGROUND: Enterobacter is among the main etiologies of hospital-acquired infections. This study aims to identify the risk factors of acquisition and attributable mortality of Enterobacter bacteremia. METHODS: Observational, case-control study for risk factors and prospective cohort for outcomes of consecutive cases with Enterobacter bacteremia. This study was conducted in five hospitals in Spain over a three-year period. Matched controls were patients with negative blood cultures and same sex, age, and hospitalization area. RESULTS: The study included 285 cases and 570 controls. E. cloacae was isolated in 198(68.8%) cases and E. aerogenes in 89(31.2%). Invasive procedures (hemodialysis, nasogastric tube, mechanical ventilation, surgical drainage tube) and previous antibiotics or corticosteroids were independently associated with Enterobacter bacteremia. Its attributable mortality was 7.8%(CI95%2.7-13.4%), being dissimilar according to a McCabe index: non-fatal=3.2%, ultimately fatal=12.9% and rapidly fatal=0.12%. Enterobacter bacteremia remained an independent risk factor for mortality among cases with severe sepsis or septic shock (OR 5.75 [CI95%2.57-12.87], p<0.001), with an attributable mortality of 40.3%(CI95%25.7-53.3). Empiric therapy or antibiotic resistances were not related to the outcome among patients with bacteremia. CONCLUSIONS: Invasive procedures, previous antibiotics and corticosteroids predispose to acquire Enterobacter bacteremia. This entity increases mortality among fragile patients and those with severe infections. Antibiotic resistances did not affect the outcome.

[Utility of molecular biology techniques in the diagnosis of sexually transmitted diseases and genital infections]. / Utilidad de las técnicas de biología molecular en el diagnóstico de las infecciones de transmisión sexual y otras infecciones genitales.

Historically, the diagnosis of sexually transmitted diseases (STDs) has been difficult. The introduction of molecular biology techniques in microbiological diagnosis and their application to non-invasive samples has produced significant advances in the diagnosis of these diseases. Overall, detection of Neisseria gonorrhoeae by molecular biology techniques provides a presumptive diagnosis and requires confirmation by culture in areas with a low prevalence. For Chlamydia trachomatis infections, these techniques are considered to be the most sensitive and specific procedures for mass screening studies, as well as for the diagnosis of symptomatic patients. Diagnosis of Mycoplasma genitalium infection by culture is very slow and consequently molecular techniques are the only procedures that can provide relevant diagnostic information. For Treponema pallidum, molecular techniques can provide direct benefits in the diagnosis of infection. Molecular techniques are not established for the routine diagnosis of donovanosis, but can be recommended when performed by experts. Molecular methods are advisable in Haemophilus ducreyi, because of the difficulties of culture and its low sensitivity. In genital herpes, molecular techniques have begun to be recommended for routine diagnosis and could soon become the technique of choice. For other genital infections, bacterial vaginosis, vulvovaginal candidosis and trichomoniasis, diagnosis by molecular methods is poorly established. With genital warts, techniques available for screening and genotyping of endocervical samples could be used for certain populations, but are not validated for this purpose.

[Update on the epidemiology, diagnosis and treatment of sexually-transmitted infections]. / Panorama actual de la epidemiología, diagnóstico y tratamiento de las infecciones de transmisión sexual.

In the last decade, cases of sexually-transmitted infections (STIs) have progressively increased in Europe. The reasons for this increase are unclear, but may involve changes in social behavior, migration and international travel, coupled with the emergence of risk groups that have not been taken into sufficient consideration to date. The routine use of molecular diagnostic techniques for many of these infections has solved many problems of sensitivity and the suitability of samples for microbiological diagnosis: non-invasive samples can be used, which has undoubtedly contributed to the increase in the number of cases. Moreover, molecular methods have also been introduced for antibiotic and antiviral susceptibility testing, as well as for molecular characterization of clinical isolates. All of these factors, together with the approval of the vaccine against the human papillomavirus, have changed the landscape of STIs across Europe.

Antibióticos y resistencia antibiótica en la quimioprofilaxis de la enfermedad meningocócica / Antibiotics and antibiotic resistance in chemoprophylaxis of meningococcal disease

La profilaxis antibiótica debe considerarse en personas con contacto con algún caso de enfermedad meningocócica o en poblaciones con altos porcentajes de portadores de N. meningitidis. El uso de antibióticos produce una reducción significativa del riesgo de enfermedad entre los contactos; así, la rifampicina, la ciprofloxacina y la ceftriaxona se consideran como las mejores opciones para la quimioprofilaxis, sin embargo su empleo está asociado con el aumento de resistencia antibiótica. Actualmente, la tendencia a la aparición de meningococos resistentes a la rifampicina después de la profilaxis es un aspecto reconocido, aunque parece que no es un fenómeno ampliamente extendido. La aparición de resistencia de alto nivel a la rifampicina está provocada por mutaciones en el gen rpoB, aunque se puede asociar a mutaciones del locus mtr implicadas en mecanismos de expulsión y bombeo. Sin embargo, los cambios en el gen rpoB dan lugar a cepas poco adaptadas a la supervivencia y este costo biológico podría explicar la ausencia de diseminación clonal de los aislamientos con resistencia adquirida a la rifampicina. La resistencia o sensibilidad disminuida a la ciprofloxacina se relaciona con mutaciones en la región determinante de resistencia a quinolonas (QRDR) del gen gyrA, además existen datos que apoyan la existencia de mecanismos de expulsión. Hasta el momento, la resistencia o la sensibilidad reducida a las quinolonas ha avanzado lentamente. No se han comunicado problemas de resistencia a la ceftriaxona, siendo la opción más segura para su uso en quimioprofilaxis.La espiramicina no es una opción adecuada aunque sigue siendo recomendada por la OMS.