Tumor-localized interleukin-2 and interleukin-12 combine with radiation therapy to safely potentiate regression of advanced malignant melanoma in pet dogs.

The clinical use of interleukin-2 and -12 cytokines against cancer is limited by their narrow therapeutic windows due to on-target, off-tumor activation of immune cells when delivered systemically. Engineering IL-2 and IL-12 to bind to extracellular matrix collagen allows these cytokines to be retained within tumors after intralesional injection, overcoming these clinical safety challenges. While this approach has potentiated responses in syngeneic mouse tumors without toxicity, the complex tumor-immune interactions in human cancers are difficult to recapitulate in mouse models of cancer. This has driven an increased role for comparative oncology clinical trials in companion (pet) dogs with spontaneous cancers that feature analogous tumor and immune biology to human cancers. Here, we report the results from a dose-escalation clinical trial of intratumoral collagen-binding IL-2 and IL-12 cytokines in pet dogs with malignant melanoma, observing encouraging local and regional responses to therapy that may suggest human clinical benefit with this approach.

Characterization of PAHs bound to ambient ultrafine particles around runways at an international airport.

The impact of airport activities on air quality, is not sufficiently documented. In order to better understand the magnitude and properly assess the sources of emissions in the sector, it is necessary to establish databases with real data on those pollutants that could have the greatest impact on both health and the environment. Particulate matter (PM), especially ultrafine particles, are a research priority, not only because of its physical properties, but also because of its ability to bind highly toxic compounds such as polycyclic aromatic hydrocarbons (PAHs). Samples of PM were collected in the ambient air around the runways at Barajas International Airport (Madrid, Spain) during October, November and December 2021. Samples were gathered using three different sampling systems and analysed to determine the concentration of PAHs bound to PM. A high-volume air sampler, a Berner low-pressure impactor, and an automated off-line sampler developed in-house were used. The agreement between the samplers was statistically verified from the PM and PAH results. The highest concentration of PM measured was 31 µg m-3, while the concentration of total PAH was 3 ng m-3, both comparable to those recorded in a semi-urban area of Madrid. The PAHs showed a similar profile to the particle size distribution, with a maximum in the 0.27-0.54 µm size range, being preferentially found in the submicron size fractions, with more than 84% and around 15-20% associated to UFPs. It was found that the ratio [PAHs(m)/PM(m)] was around 10-4 in the warmer period (October), whereas it more than doubled in the colder months (November-December). It is significant the shift in the relative distribution of compounds within these two periods, with a notable increase in the 5 and 6 ring proportions in the colder period. This increase was probably due to the additional contribution of other external sources, possibly thermal and related to combustion processes, as supported by the PAH diagnostic ratios.

Informal sale of antibiotics in Guatemalan convenience stores before and after implementation of federal antibiotic dispensing legislation.

BACKGROUND: Convenience stores in Guatemala provide essential consumer goods in communities, but many dispense antibiotics illegally. Federal legislation, passed in August of 2019, requires prescriptions for antibiotic purchase at pharmacies but it is unclear if this legislation is enforced or if it has any impact on unlawful sales of antibiotics. METHODS: To determine if antibiotic availability changed in convenience stores, we carried out a repeated measures study collecting antibiotic availability data before and after implementation of the dispensing regulation. RESULTS: There was no statistical difference in the proportion of convenience stores that sold antibiotics before and after antibiotic regulations [66.6% (295/443) and 66.7% (323/484), respectively, P>0.96], nor in the number of stores selling amoxicillin [55.5% (246/443) and 52.3% (253/484), respectively, P>0.96], but fewer stores (20%) sold tetracycline capsules after regulation was passed (P<0.05). For stores visited both before and after passage of legislation (n=157), 15% stopped selling antibiotics while 25% started selling antibiotics. Antibiotics from convenience stores were reportedly sold for use in people and animals. CONCLUSIONS: Antibiotics remain widely available in convenience stores consistent with no significant change in the informal sector after implementation of prescription requirements for pharmacies. Importantly, effects from regulatory change could have been masked by potential changes in antibiotic use during the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic.

Neurogenic appendicopathy: A rare differential diagnosis of acute appendicitis.

AIM OF THE STUDY: In histologically non-inflamed but clinically suspect appendices, changes described as neurogenic appendicopathy with fibrous or fibrolipomatous obliterations can be observed. The purpose of this study was to analyse the incidence of these entities of the appendix in a longitudinal patient cohort. PATIENTS AND METHODS: This is a retrospective single-centre study of 457 patients undergoing laparoscopic appendectomy from 2017 to 2020 due to suspected acute appendicitis. RESULTS: In 72 patients (15.8%) with clinically suspected acute appendicitis, the appendix showed no distinct signs of acute inflammation during the procedure. In 43 patients, histological analysis revealed neurogenic appendicopathy or fibrous and fibrolipomatous obliteration. Female gender (P=0.088), younger age (P<0.0001), longer pain duration (P<0.0001) and repetitive pain episodes were more frequent in these patients than in those with acute appendicitis. Inflammation markers were also decreased in the group of patients with neurogenic appendicopathy (leukocytes 9.8±3.5 vs. 13.0±4.5 G/L and C-reactive protein 38.7±60.7 vs. 59.4±70.5mg/L). CONCLUSION: Neurogenic appendicopathy with fibrous/fibrolipomatous obliteration is a differential diagnosis of acute appendicitis that can only be confirmed by pathology. Female gender, young age, prolonged duration with repetitive episodes of pain, and relatively low inflammatory markers are evocative of this diagnosis.

Is unicentric familial papillary thyroid microcarcinoma different from multicentric?

BACKGROUND: Familial papillary thyroid microcarcinoma (FPTMC) appears to be more aggressive than sporadic papillary thyroid microcarcinoma (SPTMC). However, there are authors who indicate that unicentric FPTMC has a similar prognosis to SPTMC. The objective is to analyze whether unicentric FPTMC has a better prognosis than multicentric FPTMC. DESIGN AND METHODS: Type of study: National multicenter longitudinal analytical observational study. STUDY POPULATION: Patients with FPTMC. STUDY GROUPS: Two groups were compared: Group A (unicentric FPTMC) vs. Group B (multicentric FPTMC). STUDY VARIABLES: It is analyzed whether between the groups there are: a) differentiating characteristics; and b) prognostic differences. STATISTICAL ANALYSIS: Cox regression analysis and survival analysis. RESULTS: Ninety-four patients were included, 44% (n = 41) with unicentric FPTMC and 56% (n = 53) with multicentric FPTMC. No differences were observed between the groups according to socio-familial, clinical or histological variables. In the group B a more aggressive treatment was performed, with higher frequency of total thyroidectomy (99 vs. 78%; p = 0.003), lymph node dissection (41 vs. 15%; p = 0.005) and therapy with radioactive iodine (96 vs. 73%; p = 0.002). Tumor stage was similar in both groups (p = 0.237), with a higher number of T3 cases in the group B (24 vs. 5%; p = 0.009). After a mean follow-up of 90 ± 68.95 months, the oncological results were similar, with a similar disease persistence rate (9 vs. 5%; p = 0.337), disease recurrence rate (21 vs. 8%; p = 0.159) and disease-free survival (p = 0.075). CONCLUSIONS: Unicentric FPTMC should not be considered as a SPTMC due to its prognosis is similar to multicentric FPTMC.

Base pairs with 4-amino-3-nitrobenzonitrile: comparison with the natural WC pairs. Dimer and tetramer forms, Infrared and Raman spectra, and several proposed antiviral modified nucleosides.

Base pairs of 4-amino-3-nitrobenzonitrile (4A-3NBN) molecule with uracil, thymine and cytosine nucleobases were optimized and compared to natural Watson-Crick (WC) pairs. The slightly greater flexibility of the -NO2 group of 4A-3NBN than the N3-H group of the natural nucleobases together with a noticeable higher dipole moment of its pairs can facilitate disruption of the DNA/RNA helix formation. Several new mutagenic modified nucleosides with 4A-3NBN and 3-amino-2-nitrobenzonitrile (3A-2NBN) were proposed as antiviral prodrugs and their base pairs optimized. The special characteristics of these prodrugs appear appropriated for their clinical use. The counterpoise (CP) corrected interaction energies of the base pairs were calculated and compared to the natural ones. The M06-2X DFT method was used for this purpose. The molecular structure of 4A-3NBN was analyzed in detail and the crystal unit cell was simulated by a tetramer form and eight dimer forms. The performance of the B3LYP, X3LYP and M06-2X methods was tested on the vibrational wavenumbers in the monomer, dimer and tetramer forms of 4A-3NBN. The observed IR and Raman bands were assigned according to the optimum dimer II form determined by B3LYP and by the tetramer form calculated by M06-2X, which is the expected unit cell that forms the crystal net. The two best scaling procedures were used.Communicated by Ramaswamy H. Sarma.

Biological behavior of familial papillary thyroid microcarcinoma: Spanish multicenter study.

PURPOSE: Familial papillary thyroid microcarcinoma (FPTMC) can present a more aggressive behavior than the sporadic microcarcinoma. However, few studies have analyzed this situation. The objective is to analyze the recurrence rate of FPTMC and the prognostic factors which determine that recurrence in Spain. METHODS: Spanish multicenter longitudinal analytical observational study was conducted. Patients with FPTMC received treatment with curative intent and presented cure criteria 6 months after treatment. Recurrence rate and disease-free survival (DFS) were analyzed. Two groups were analyzed: group A (no tumor recurrence) vs. group B (tumor recurrence). RESULTS: Ninety-four patients were analyzed. During a mean follow-up of 73.3 ± 59.3 months, 13 recurrences of FPTMC (13.83%) were detected and mean DFS was 207.9 ± 11.5 months. There were multifocality in 56%, bilateral thyroid involvement in 30%, and vascular invasion in 7.5%; that is to say, they are tumors with histological factors of poor prognosis in a high percentage of cases. The main risk factors for recurrence obtained in the multivariate analysis were the tumor size (OR: 2.574, 95% CI 1.210-5.473; p = 0.014) and the assessment of the risk of recurrence of the American Thyroid Association (ATA), both intermediate risk versus low risk (OR: 125, 95% CI 10.638-1000; p < 0.001) and high risk versus low risk (OR: 45.454, 95% CI 5.405-333.333; p < 0.001). CONCLUSION: FPTMC has a recurrence rate higher than sporadic cases. Poor prognosis is mainly associated with the tumor size and the risk of recurrence of the ATA.

Biomarkers associated with survival and favourable outcome of radioembolization with yttrium-90 glass microspheres for colon cancer liver metastases: Single centre experience.

OBJECTIVE: To determine the therapeutic effectiveness and safety of transarterial radioembolization (TARE) with Yttrium-90 in patients with colorectal cancer (CRC) liver metastases and to evaluate the prognostic value of different biomarkers. MATERIAL AND METHODS: This prospective longitudinal study enrolled consecutive patients with CRC liver metastases treated with TARE between November 2015 and june 2020. The therapeutic response at three and six months (RECIST1.1 criteria) and the relationship of biomarkers with therapeutic response, by calculating objective tumor response rates (ORR) and disease control (DCR), and overall survival (OS) and progression-free (PFS). RESULTS: Thirty TAREs were performed in 23 patients (mean age, 61.61 ±â€¯9.13 years; 56.5% male). At three months, the objective response rate (ORR) was 16.7% and the disease control rate (DCR) 53.3%. At six months, the disease progressed in 80%. The ORR and DCR were significantly associated with age at diagnosis (P = 0.047), previous bevacizumab treatment (P = 0.008), pre-TARE haemoglobin (P = 0.008), NLR (P = 0.040), pre-TARE albumin (P = 0.012), pre-TARE ALT (P = 0.023) and tumour-absorbed dose > 115 Gy (P = 0.033). Median overall survival (OS) was 12 months (95% CI, 4.75-19.25 months) and median progression-free survival (PFS) 3 months (95% CI, 2.41-3.59). OS was significantly associated with primary tumour resection (P = 0.019), KRAS mutation (HR: 5.15; P = 0.024), pre-TARE haemoglobin (HR: 0.50; p = 0.009), pre-TARE NLR (HR: 1.65; P = 0.005) and PLR (HR: 1.01; P = 0.042). CONCLUSION: TARE prognosis and therapeutic response were predicted by different biomarkers, ranging from biochemical parameters to tumour dosimetrics.

Virtual Simulation for Last-Year Nursing Graduate Students in Times of Covid-19: A Quasi-Experimental Study.

BACKGROUND: The COVID-19 pandemic has made it necessary to adapt university health-education. Virtual simulation has been proposed to be a suitable tool. METHODS: A quasi-experimental study was conducted on nursing students in the final year. The virtual simulation platform vSim® was used. Improvements in knowledge, skills during simulation, satisfaction and selfconfidence obtained through the training provided were analyzed, as well as satisfaction with the platform. RESULTS: Prepost training knowledge improved. Skill acquisition improved between the first and last attempts in all cases. The levels of selfconfidence and satisfaction with the training and the platform used were high. CONCLUSIONS: The vSim® was a useful solution during the pandemic. Knowledge improved and high selfconfidence was obtained.

Biomarkers associated with survival and favourable outcome of radioembolization with yttrium-90 glass microspheres for colon cancer liver metastases: Single centre experience. / Biomarcadores asociados con la supervivencia y la respuesta terapéutica a la radioembolización con esferas cargadas de itrio-90 en las metástasis hepáticas del carcinoma colorrectal: nuestra experiencia.

OBJETIVE: To determine the therapeutic effectiveness and safety of transarterial radioembolization (TARE) with Yttrium-90 in patients with colorectal cancer (CRC) liver metastases and to evaluate the prognostic value of different biomarkers. MATERIAL AND METHODS: This prospective longitudinal study enrolled consecutive patients with CRC liver metastases treated with TARE between November 2015 and june 2020. The therapeutic response at three and six months (RECIST1.1 criteria) and the relationship of biomarkers with therapeutic response, by calculating objective tumor response rates (ORR) and disease control (DCR), and overall survival (OS) and progression-free (PFS). RESULTS: Thirty TAREs were performed in 23 patients (mean age, 61,61±9,13 years; 56,5% male). At three months, the objective response rate (ORR) was 16,7% and the disease control rate (DCR) 53,3%. At six months, the disease progressed in 80%. The ORR and DCR were significantly associated with age at diagnosis (P=.047), previous bevacizumab treatment (P=.008), pre-TARE haemoglobin (P=.008), NLR (P=.040), pre-TARE albumin (P=.012), pre-TARE ALT (P=.023) and tumour-absorbed dose>115Gy (P=.033). Median overall survival (OS) was 12 months (95% CI, 4.75-19.25 months) and median progression-free survival (PFS) 3 months (95% CI, 2.41-3.59). OS was significantly associated with primary tumour resection (P=.019), KRAS mutation (HR: 5.15; P=.024), pre-TARE haemoglobin (HR: .50; p=.009), pre-TARE NLR (HR: 1.65; P=.005) and PLR (HR: 1.01; P=.042). CONCLUSION: TARE prognosis and therapeutic response were predicted by different biomarkers, ranging from biochemical parameters to tumour dosimetrics.

[Anterior cutaneous nerve entrapment syndrome: a frequently overlooked cause of chronic abdominal pain in children].

Anterior cutaneous nerve entrapment syndrome (ACNES) is often overlooked in the differential diagnosis of chronic abdominal pain (CAP). An 11-year-old boy with CAP previously studied in emergency and digestive services without detecting organic pa-thology, suggesting a psychosomatic origin. On examination, he showed pain in the abdominal wall located to the area of the terminal branch of the Th11 intercostal nerve, with a positive Carnett's sign and a favorable response to injection with local anesthetic at the trigger point. Somatosensory evoked potentials revealed right anterior rectus nerve neuropathy. He was diagnosed with ACNES. As treatment, an ultrasound-guided subfascial injection with lidocaine and dexame-thasone into the trigger point was administered. After four months, he remains asymptomatic. For the treatment of ACNES in pediatrics patients, a step-up strategy should be applied, starting with trigger point in-jections of lidocaine and dexamethasone and reserving anterior neurectomy for those cases with limited effect of these injections.

Optimal treatment sequencing of abiraterone acetate plus prednisone and enzalutamide in patients with castration-resistant metastatic prostate cancer: A systematic review and meta-analysis.

PURPOSE: To evaluate the impact of the hormonal treatment sequencing including abiraterone acetate plus prednisone (AAP) and enzalutamide (ENZ) in mCRPC, and determine which sequence provides more benefits for patients. METHODS: Studies published in English between 1 January 2013 and 30 September 2017 were identified in PubMed and EMBASE electronic databases. Studies assessing the efficacy of treatment sequences, based on AAP and ENZ, in mCRPC patients, were eligible for analysis. RESULTS: Seventeen studies met the inclusion criteria. Two assessed both treatment sequences AAP â†’ ENZ and ENZ â†’ AAP; it was found that sequence of AAP â†’ ENZ showed a statistically significantly longer PSA-PFS than the observed in ENZ â†’ AAP (pooled HR: 0,54; 95% CI; 0,36-0,82; p < 0,05). The nine studies analysing Doc â†’ AAP â†’ ENZ sequence, revealed favourable results in terms of PFS. The 5 studies which analysed AAP â†’ ENZ sequence, show a decrease in PSA levels ≥ 50% in 11-41% of patients treated with enzalutamide after previous treatment with AAP. In the two studies that analysed the Doc â†’ ENZ â†’ AAP sequence, PSA response rates were much lower than those reported with Doc â†’ AAP â†’ ENZ, with decreases in PSA ≥ 30 of 3-18% and PSA ≥ 50 of 8-11%. CONCLUSION: Significant clinical efficacy of AAP administered as the first-line treatment in mCRPC patients followed by enzalutamide, delaying disease progression, compared with the ENZ â†’ AAP sequence. However, more studies and randomized trials are needed, to validate the best treatment sequencing.

Piezoelectric bone surgery for impacted lower third molar extraction compared with conventional rotary instruments: a systematic review, meta-analysis, and trial sequential analysis.

The aim of this study was to evaluate whether piezoelectric bone surgery (PBS) for impacted lower third molar extraction reduces the surgical time and risk of intra- and postoperative complications in comparison with conventional rotary instruments. This meta-analysis followed the PRISMA guidelines and was registered in the PROSPERO database. The PubMed, Embase, Scopus, and OpenGrey databases were screened for articles published from January 1, 1990 to December 31, 2018. Selection criteria included randomized controlled trials (RCTs) comparing PBS with conventional rotary instruments for impacted lower third molar extraction and reporting any of the clinical outcomes (intra- and postoperative complications and duration of surgery) for both groups. A risk of bias assessment was performed using the Cochrane Collaboration tool. A meta-analysis was performed, and the power of the meta-analytic findings was assessed by trial sequential analysis (TSA). Strong evidence suggests that PBS prolongs the duration of surgery and low evidence suggests that PBS reduces postoperative morbidity (pain and trismus) in comparison with rotary instruments. Data were insufficient to determine whether PBS reduces neurological complications and postoperative swelling in comparison with burs.

Anti-inflammatory, pro-proliferative and antimicrobial potential of the compounds isolated from Daemonorops draco (Willd.) Blume.

ETHNO-PHARMACOLOGICAL RELEVANCE: Daemonorops draco (D. draco) commonly known as "Dragon's blood" is one of the most used plants by Momok, Anak Dalam and Talang Mamak tribes from Indonesia as a remedy for wound healing. AIM OF THE STUDY: This study aimed to identify the extract, fractions and compounds responsible for the anti-inflammatory and pro-proliferative activities of the D. draco resin. Additionally, the antimicrobial activity against two bacteria and one yeast species was analysed. MATERIALS AND METHODS: Bio-guided isolation of compounds with anti-inflammatory, pro-proliferative and antimicrobial activities from the D. draco resin was carried out by measuring: the inhibition of NF-κB and activation of Nrf2 in THP-1, HaCaT, NIH-3T3 cells; cell proliferation in NIH-3T3 and HaCaT cells; and the antimicrobial effect on E. coli, S. aureus and C. albicans. RESULTS: Guided isolation by bioassay gave rise to the isolation and characterisation by nuclear magnetic resonance and mass spectrometry of three compounds: 1 (Bexarotene), 2 (Taspine) and 3 (2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone). All compounds showed NF-κB inhibitory activity with IC50 values of 0.10-0.13, 0.22-0.24 and 3.75-4.78 µM, respectively, while the positive control, Celastrol, had an IC50 of 7.96 µM. Likewise, all compounds showed an activating effect of Nrf2 with EC50 values of 5.34-5.43, 163.20-169.20 and 300.82-315.56 nM, respectively, while the positive control, CDDO-Me, had an EC50 of 0.11 nM. In addition, concerning the pro-proliferative activity, compound 1 (IC50 = 8.62-8.71 nM) showed a capacity of 100%, compound 2 (IC50 = 166-171 nM) showed a capacity of 75%, and compound 3 (IC50 = 469-486 nM) showed a capacity of 65%, while FSB 10% (positive control) had a pro-proliferative activity of 100% in the NIH3T3 cell lines (fibroblasts) and HaCaT (keratinocytes). Finally, all the compounds showed antimicrobial activity with MIC values of 0.12-0.16, 0.31-0.39 and 3.96-3.99 µM, respectively, in S. aureus, E. coli and C. albicans strains, while the positive control, Ofloxacin, had a MIC of 27.65 µM. CONCLUSION: This study managed to isolate, for the first time, three compounds (Bexarotene, Taspine and 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone) from the resin of D. draco, with anti-inflammatory, and pro-proliferative as well as antimicrobial activities.

Hypokalemia as a sensitive biomarker of disease severity and the requirement for invasive mechanical ventilation requirement in COVID-19 pneumonia: A case series of 306 Mediterranean patients.

OBJECTIVES: Serum levels of potassium (K+) appear to be significantly lower in severe cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the clinical significance of this is unknown. The objective was to investigate whether hypokalemia acts as a biomarker of severity in coronavirus disease 2019 (COVID-19) pneumonia and is associated with major clinical outcomes. METHODS: A retrospective cohort study of inpatients with COVID-19 pneumonia (March 3 to May 2, 2020) was performed. Patients were categorized according to nadir levels of K+ in the first 72 h of admission: hypokalemia (K+ ≤3.5 mmol/l) and normokalemia (K+ >3.5 mmol/l). The main outcomes were all-cause mortality and the need for invasive mechanical ventilation (IMV); these were analyzed by multiple logistic regression (odds ratio (OR), 95% confidence interval (CI)). RESULTS: Three hundred and six patients were enrolled. Ninety-four patients (30.7%) had hypokalemia and these patients showed significantly higher comorbidity (Charlson comorbidity index ≥3, 30.0% vs 16.3%; p =  0.02) and CURB65 scores (median (interquartile range): 1.5 (0.0-3.0) vs 1.0 (0.0-2.0); p =  0.04), as well as higher levels of some inflammatory parameters at baseline. After adjustment for confounders, hypokalemia was independently associated with requiring IMV during the admission (OR 8.98, 95% CI 2.54-31.74). Mortality was 15.0% (n = 46) and was not influenced by low K+. Hypokalemia was associated with longer hospital and ICU stays. CONCLUSIONS: Hypokalemia is prevalent in patients with COVID-19 pneumonia. Hypokalemia is an independent predictor of IMV requirement and seems to be a sensitive biomarker of severe progression of COVID-19.

Analysis of bacterial communities of infected primary teeth in a Mexican population.

BACKGROUND: The objective of this study was to describe the bacterial communities associated with pediatric patients with endodontic infections of temporal teeth by targeting the 16S rRNA gene using pyrosequencing. MATERIAL AND METHODS: Microbiological samples were obtained from the lower primary molars of thirteen 13 pediatric patients with dental infections. An aspiration method for microbiological sampling was used. The identification of microbiota employing the pyrosequencing method by targeting the 16S gene was performed. RESULTS: Ribosomal 16S RNA gene sequences were amplified, obtaining a total of 16,182 sequences from 13 primary infected molars (13 different individuals) by pyrosequencing. Bacteroidetes phyla (35.15%) were the most abundant followed by Firmicutes (33.3%) and Fusobacteria (10.05%); the presence of specific pathogenic bacteria was determined as well. CONCLUSIONS: The infected root canal of primary teeth contains a high diversity of anaerobic bacteria, and Bacteroidetes, Firmicutes, and Fusobacteria phyla were the most abundant; Prevotella and Streptococcus genera were the most prevalent.

High prevalence of t895 and t9364 spa types of methicillin-resistant Staphylococcus aureus in a tertiary-care hospital in Mexico: different lineages of clonal complex 5.

BACKGROUND: Staphylococcus aureus is a leading cause of broad-spectrum infections both in the community and within healthcare settings. Methicillin-resistant Staphylococcus aureus (MRSA) has become a global public health issue. The aim of this study was to examine the clinical and molecular characteristics of Staphylococcus aureus isolates and to define the population structure and distribution of major MRSA clones isolated in a tertiary-care hospital in Mexico. RESULTS: From April 2017 to April 2018, 191 Staphylococcus aureus isolates were collected. The frequency of MRSA was 26.7%; these strains exhibited resistance to clindamycin (84.3%), erythromycin (86.2%), levofloxacin (80.3%), and ciprofloxacin (86.3%). The majority of MRSA strains harbored the SCCmec type II (76.4%) and t895 (56.8%) and t9364 (11.7%) were the most common spa types in both hospital-associated MRSA and community-associated MRSA isolates. ST5-MRSA-II-t895 (New York /Japan clone) and ST1011-MRSA-II-t9364 (New York /Japan-Mexican Variant clone) were the most frequently identified clones. Furthermore, different lineages of Clonal Complexes 5 (85.4%) and 8 (8.3%) were predominantly identified in this study. CONCLUSION: Our study provides valuable information about the epidemiology of MRSA in a city of the central region of Mexico, and this is the first report on the association between t895 and t9364 spa types and ST5 and ST1011 lineages, respectively. These findings support the importance of permanent surveillance of MRSA aimed to detect the evolutionary changes of the endemic clones and the emergence of new strains.