Potential Anti-Infectious Activity of Essential Oil Chemotypes of Lippia origanoides Kunth on Antibiotic-Resistant Staphylococcus aureus Strains.

Staphylococcus aureus infections are prevalent in healthcare and community environments. Methicillin-resistant S. aureus is catalogued as a superbug of high priority among the pathogens. This Gram-positive coccus can form biofilms and produce toxins, leading to persistent infection and antibiotic resistance. Limited effective antibiotics have encouraged the development of innovative strategies, with a particular emphasis on resistance mechanisms and/or virulence factors. Medicinal aromatic plants have emerged as promising alternative sources. This study investigated the antimicrobial, antibiofilm, and antihemolysis properties of three different chemotypes of Lippia origanoides essential oil (EO) against susceptible and drug-resistant S. aureus strains. The chemical composition of the EO was analyzed using GC-MS, revealing high monoterpene concentrations, with carvacrol and thymol as the major components in two of the chemotypes. The third chemotype consisted mainly of the sesquiterpene ß-caryophyllene. The MIC values for the two monoterpene chemotypes ranged from 62.5 to 500 µg/mL for all strains, whereas the sesquiterpene chemotype showed activity against seven strains at concentrations of 125-500 µg/mL, which is the first report of its anti-S. aureus activity. The phenolic chemotypes inhibited biofilm formation in seven S. aureus strains, whereas the sesquiterpene chemotype only inhibited biofilm formation in four strains. In addition, phenolic chemotypes displayed antihemolysis activity, with IC50 values ranging from 58.9 ± 3.8 to 128.3 ± 9.2 µg/mL. Our study highlights the importance of L. origanoides EO from the Yucatan Peninsula, which has the potential for the development of anti-S. aureus agents.

[Gram-negative bacteria of critical priority in ICU patients from a tertiary care hospital]. / Bacterias Gram-negativas de prioridad crítica en pacientes de las UCI de un hospital de tercer nivel.

Background: Intensive care units (ICU) are the epicenter of antimicrobial resistance (AMR), and patients' infections are mainly caused by Gram-negative bacteria (GNB). Objective: To describe the frequency and trends in AMR of GNB deriving from the clinical samples of ICU patients at a tertiary care hospital in Mérida, Yucatán. Material and methods: Study which included the review of laboratory reports of all bacteriological samples collected from patients admitted to neonatal, pediatric and adult ICU from January 1 2019 to December 31 2021. Results: 433 GNB isolates were recovered, with Klebsiella pneumoniae being the most predominant isolate (n = 117; 27.02%). The majority of GNB were recovered from bronchial secretions (n = 163). Overall, GNB showed high resistance rates to ampicillin (89.48%), ampicillin/sulbactam (66.85%), cephalosporins (58.52-93.81%), tobramycin (58.06%), and tetracycline (61.73%). Among GNB, 73.90% and 68.53% exhibited multidrug-resistant, and highly resistant microorganisms' profiles, respectively, and 47.54% of Acinetobacter baumannii exhibited an extensively drug-resistant profile. A total of 80.33% of A. baumannii was carbapenem-resistant, and 83.76% of K. pneumoniae strains were ESBL-producing. Conclusion: Our data could be helpful to improve the empirical therapy and the infection-control program.

Introducción: las unidades de cuidados intensivos (UCI) son el epicentro de la resistencia a los antimicrobianos (RAM) y las infecciones en estas áreas son causadas principalmente por bacterias Gram-negativas (BGN). Objetivo: describir la frecuencia y los patrones de RAM en BGN aisladas de muestras clínicas de pacientes de las UCI de un hospital de tercer nivel en Mérida, Yucatán. Material y métodos: estudio que incluyó la revisión de los reportes de laboratorio de las muestras bacteriológicas obtenidas de pacientes ingresados en las UCI neonatal, pediátrica y adulta del 1 de enero de 2019 al 31 de diciembre de 2021. Resultados: se identificaron 433 BGN y Klebsiella pneumoniae fue el patógeno más prevalente (n = 117; 27.02%). La mayoría de las BGN aisladas se obtuvieron de secreciones bronquiales (n = 163). En general, las BGN mostraron altas tasas de resistencia a ampicilina (89.48%), ampicilina/sulbactam (66.85%), cefalosporinas (58.52-93.81%), tobramicina (58.06%) y tetraciclina (61.73%). El 73.90% y el 68.53% de las BGN exhibieron perfiles multidrogorresistentes y microorganismos altamente resistentes a fármacos, respectivamente, y 47.54% de los aislamientos de Acinetobacter baumannii mostró perfil de drogorresistencia extendida. El 80.33% de los A. baumannii fue resistente a carbapenémicos y el 83.76% de las K. pneumoniae fueron productoras de BLEE. Conclusión: nuestros datos podrían mejorar la terapia antimicrobiana empírica y el programa de control de infecciones.

Antimicrobial potential of the Mayan medicine plant Matayba oppositifolia (A. Rich.) Britton against antibiotic-resistant priority pathogens.

ETHNOPHARMACOLOGICAL RELEVANCE: The bark of Matayba oppositifolia (A. Rich.) Britton (commonly known as "huaya" or "palo huacax") is commonly utilized in traditional Mayan medicine for treating diarrhea and for canker and other sores. AIM OF THE STUDY: The aim of this study was to investigate the in-vitro antimicrobial activity of M. oppositifolia bark extracts against drug-susceptible and -resistant ESKAPE-E pathogens. In addition, the phytochemical composition of the best antibacterial extract was analyzed. MATERIALS AND METHODS: The bark extracts were prepared with different solvents, including water, n-hexane, ethyl acetate and methanol. These were tested against ESKAPE-E (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp., including Escherichia coli) strains using Resazurin Microtiter Assay. In addition, the composition of the most active extract was analyzed by GC-MS. RESULTS: The aqueous and organic bark extracts showed activity on drug-susceptible and -resistant ESKAPE-E microbes (MIC = 1000-31.25 µg/mL). The n-hexane bark extract was more active against the superbugs carbapenem-resistant K. pneumoniae (MIC = 500-31.25 µg/mL) and A. baumannii (MIC = 250-125 µg/mL). The GC-MS analysis of this extract allowed the identification of 12 phytochemicals as the potential antibacterial compounds. The major compounds identified were palmitic acid (1), friedelan-3-one (2) and 7-dehydrodiosgenin (3). CONCLUSION: The present study reveals the strong in-vitro antibacterial activity of the n-hexane extract from the bark of M. oppositifolia and demonstrates the potential of natural products as a source of antibacterial compounds or phytomedicines that are specifically effective against drug-resistant ESKAPE-E bugs. Additionally, our investigation contributes to the ethnopharmacological knowledge and reappraisal of Mayan medicinal flora, as well as supports the traditional use of the bark of the medicinal plant M. oppositifolia for the treatment of infectious diseases.

Efficacy of Fosfomycin against Planktonic and Biofilm-Associated MDR Uropathogenic Escherichia coli Clinical Isolates.

Urinary tract infections (UTI) are a severe public health problem and are caused mainly by the uropathogenic Escherichia coli (UPEC). Antimicrobial resistance and limited development of new antimicrobials have led to the reuse of old antibiotics such as fosfomycin. The aim of this study was to evaluate the in vitro efficacy of fosfomycin on a collection of multidrug-resistant (MDR) UPEC and the degradative activity on biofilm producers. A total of 100 MDR UPEC clinical isolates were collected from patients at Mexican second- and third-level hospitals. Microorganism identification was performed using an automated system, the evaluation of the susceptibility of clinical isolates to fosfomycin was performed using the resazurin microtiter assay, and the identification of biofilm producers and the effect of fosfomycin in biofilms were evaluated using the crystal violet method. Among planktonic MDR UPEC, 93% were susceptible to fosfomycin. Eighty-three MDR UPEC were categorized as weak (39.8%), moderate (45.2%), and strong (14.5%) biofilm producers. Fosfomycin exhibited degradative activity ranging from 164.4 µg/mL to 1045 µg/mL. Weak producers required statistically lower concentrations of fosfomycin to destroy the biofilm, contrary to moderate and strong producers. In conclusion, fosfomycin could be an option for the treatment of infections caused by MDR UPEC, for which the antimicrobial treatment is more often becoming limited.