Frequency Of Isolation Research Articles

Twelve-Year Dynamics of Leading Pathogens Spectrum Causing Orthopedic Infection: A Retrospective Study

Background. The number of surgeries on the musculoskeletal system is increasing every year. Along with the increasing access to orthopedic care, the number of patients with orthopedic infection, the etiological agents of which can be from various taxonomic groups, is also increasing. Staphylococcus aureus and different types of coagulase-negative staphylococci (CoNS), including S. epidermidis and S. lugdunensis, together are the causative agents in 70% of cases.
 Aim of the study — to analyze the dynamics of the microbial spectrum isolated from patients of the septic surgery department for the period from 2011 to 2022.
 Methods. We performed a retrospective analysis of the microbial spectrum isolated from patients who were treated in the septic surgery department from January 1, 2011 to December 31, 2022. The leading pathogens were microorganisms whose share in the spectrum exceeded 3.5%. Of the isolated pathogens, 48.8% were the only etiological agents, and microbial associations were detected in 51.2% of the isolated pathogens.
 Results. A total of 10,327 bacteria strains were identified over the 12-year period. The leading microorganisms causing orthopedic infection were Staphylococcus spp., Enterococcus spp., Propionibacterium spp., Pseudomonas aeruginosa, Corynebacterium spp., Streptococcus spp., Klebsiella spp. and Acinetobacter spp. In the dynamics of isolated pathogens during the analyzed period, several trends were determined: a decrease in the shares of S. aureus, Enterococcus spp., P. aeruginosa, Acinetobacter spp. and an increase in the shares of CoNS and Corynebacterium spp.
 Conclusion. During 12 years, in the microbial spectrum of orthopedic infection in patients of the septic surgery department of our Center, Gram-positive bacteria, in the majority representatives of the genus Staphylococcus, prevailed. At the same time, a significant decrease in the share of S. aureus strains and an increase in the frequency of isolation of various species of CoNS were registered. A significant decrease in the number of non-fermenting Gram-negative bacteria was also revealed.

Frequency of drug-resistant bacterial isolates among pregnant women with UTI in maternity and children’s hospital, Bisha, Saudi Arabia

Urinary tract infections (UTIs) are one of the most prevalent bacterial infections affecting humans, with a higher incidence among women. Pregnant women are at an increased risk of developing UTIs, which can have detrimental consequences for both the mother and fetus. UTIs can be caused by various bacteria, and the prevalence of drug-resistant UTIs in maternity and children’s hospitals is a cause for concern due to the potential for severe complications if left untreated. The primary objective of the current study was to determine the distribution of UTI-causing bacteria and investigate the antibiotic sensitivity patterns of isolated cultures obtained from pregnant women with UTIs at the Maternity and Children’s Hospital, Bisha, Saudi Arabia. This cross-sectional study was conducted from October 2021 to October 2023, involving the analysis of urine samples collected from 321 participants who acquired UTIs during pregnancy. Using biochemical tests and standard cultures, the urine samples were examined for pathogenic bacteria and their anti-microbial sensitivity patterns. The study analyzed susceptibility results according to the Clinical Laboratory Standards Institute guidelines (M100, 28th Edition, 2018). Bacterial strains demonstrating resistance to three or more antibiotics were classified as multidrug-resistant (MDR). This study revealed the distribution of UTI-causing bacteria to be as follows: Escherichia coli, 57.01%; Klebsiella pneumoniae, 24.61%; Pseudomonas aeruginosa, 4.36%; Proteus mirabilis and Enterobacter cloacae, 3.74%; Streptococcus agalactiae, 3.11%; Enterococcus faecalis, 2.18%; and Staphylococcus aureus, 1.24%. Antimicrobial susceptibility testing varied among gram-positive and gram-negative bacteria. Gentamicin demonstrated the highest sensitivity among both gram-positive and gram-negative bacteria; piperacillin-tazobactam was the second most effective drug against gram-negative bacteria. The bacterial isolates showed varying susceptibility to different antibiotics, with Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa being mainly sensitive to gentamicin, piperacillin-tazobactam, and ciprofloxacin, respectively. The strategies for reducing the risk of UTIs need to be improved to limit the spread of MDR bacteria. These strategies may include promoting hygienic practices and administering appropriate antibiotics to prevent the emergence and spread of drug-resistant bacteria. Further research is required to monitor the trends in antibiotic resistance among UTI-causing bacteria and develop effective strategies for managing this public health menace.

Wheat rhizosphere dynamics of Trichoderma gamsii A5MH and suppression of a Pythium root rot-Fusarium crown rot disease complex over two consecutive cropping seasons.

Determine the wheat rhizosphere competence of Trichoderma gamsii strain A5MH and in planta suppression of the Pythium root and Fusarium crown rot pathogens Globisporangium irregulare and Fusarium pseudograminearum. Wheat was continuously cropped (eight years) at a minimum tillage, low growing season rainfall (GSR≤170mm) site shown as highly conducive to Pythium root and Fusarium crown rots. Root isolation frequency (RIF) and qPCR were used to determine the rhizosphere dynamics of strain A5MH and the target pathogens at tillering, grain harvest, and in postharvest stubble over the final 2 years. Strain A5MH actively colonized the wheat rhizosphere throughout both growing seasons, had high root abundance at harvest [log 4.5 genome copies (GC) g-1] and persisted in standing stubble for at least 293-d postinoculation. Globisporangium irregulare was most abundant in roots at tillering, whereas F. pseudograminearum was only abundant at harvest and up to 9-fold greater in the drier, second year (GSR 105mm). Strain A5MH decreased RIF of both pathogens by up to 40%, root abundance of G. irregulare by 100-fold, and F. pseudogaminearum by 700-fold, but was ineffective against crown rot in the second year when pathogen abundance was>log 6.0 GC g-1 root. Strain A5MH increased crop emergence and tillering biomass by up to 40%. Further trials are required to determine if the A5MH-induced pathogen suppression translates to yield improvements in higher rainfall regions where non-cereal rotations reduce crown rot inoculum.

Analysis of the Frequency, Antibiotic Susceptibility, and Related Genes among Foodborne Pathogenic Bacteria Isolated from Hospital Refrigerators in Tehran, Iran.

Hospital refrigerators as essential food storage can be important source of food contamination. We aimed to investigate the frequency and antibiotic susceptibility of the pathogenic bacteria in three hospital refrigerators in Tehran. This study was performed on 254 samples, collected from 60 refrigerators of the various wards of three hospitals, A, B, and C, in Tehran, Iran from 2020 to 2021. Following isolation and identification of isolates, the antibiotic susceptibility pattern was determined. PCR-based assays were used to screen the presence of antibiotic resistance genes of resistant isolates. From 254 collected samples, 236 samples (92.9%) were contaminated. Most strains were isolated from refrigerators with poorly cleaned, temperatures above 8 °C in non-critical wards. Most bacteria belonging to Enterobacteriaceae (68.8%), followed by Staphylococcus (11.9%), and Enterococcus (10.6%), while the frequency of non-Enterobacteriaceae isolates was 8.9%. The highest antibiotic resistant bacteria were in extended spectrum beta-lactamase (ESBL) 9.7%, vancomycin-resistant enterococci (VRE) 5.3%, methicillin-resistant S. epidermidis (MRSE) 0.4%, and methicillin-resistant S. aureus (MRSA) 0.4%, respectively. The bla OXA-48, bla CTX, and bcla TEM genes were found only in 10% of Enterobacteriaceae isolates. The bla OXA-51 gene was found in all non-Enterobacteriaceae isolates. The vanA and mecA genes were detected in antibiotic-resistant Enterococcus and Staphylococcus. Our findings suggests major concern about cross-contamination and the emergence of antibiotic-resistant isolates as a potential health threat with hospital refrigerators origin. More attention to hospital refrigerators cleaning is necessary to prevent foodborne diseases and nosocomial infections.

Microbiological monitoring of a multidisciplinary medical organization: the basis of strategic planning in the framework of the implementation of epidemiological safety

Relevance. Monitoring of antibiotic resistance and the frequency of isolation of microorganisms at the regional level in each medical organization is of paramount importance for the implementation of epidemiological safety. Objective. To identify the main microbiological trends based on the analysis of the microflora of patients in a single — profile hospital in order to implement weaknesses in strategic planning activities. Materials and methods. A comprehensive analysis of the pharmacoepidemiological results of the consumption of antimicrobial drugs with calculated drug resistance indices and microbiological monitoring data demonstrated the presence of weaknesses and strengths for the strategic development of a multidisciplinary hospital at the regional level in terms of epidemiological safety. Results . Statistically significant differences in the microbiological structure of pathogens are predetermined by the profile of medical care. The main trends in the change in the microflora of a multidisciplinary hospital as a whole are the prevalence of fungal and gram-negative pathogens over gram-positive ones. The presence of a relatively high index of consumpion of cephalosporins of 3–4 generations, fluoroquinolones, carbapenems, protected penicillins determines the high drug resistance index of Klebsiella pneumoniae (0.86) and characterizes the main microbiological trends of a multidisciplinary clinic. Conclusion. Risk stratification by the level of multidrug-resistant pathogens, the use of deterrent strategies for prescribing antimicrobials, the implementation of educational modules, the evaluation of the effectiveness and monitoring of the risk stratification program with in the framework of antimicrobial technologies, the analysis of microbial landscape data using decision support programs are the main tasks of the functioning of a multidisciplinary team of specialists in a multidisciplinary clinic to control antibiotic resistance.

First Report of Colletotrichum aenigma causing Anthracnose on Pecan in China.

Pecan (Carya illinoinensis) is an important economic forest crops widely cultivated in China. From June to September in both 2021 and 2022, severe leaf disease resembling anthracnose was observed in 6.6-ha pecan orchard in Jintan (31°42'23.84″ N, 119°21'22.90″ E), Jiangsu Province. The disease severity was about 15 to 25% with 5 to 12% incidence on 100 surveyed trees of the orchard in 2022. Symptoms initially appeared as small gray-bark sunken lesions, which gradually developed to big sunken lesions with brown edges and irregular-shaped. Small fragments (4 × 4 mm) from the necrotic borders of infected leaves were surfaced sterilized, plated on potato dextrose agar (PDA) and then incubated in darkness at 25°C for 3 days. Pure cultures were obtained by monosporic isolation. Twenty-one isolates with similar characteristics were obtained from the infected leaves (isolation frequency about 90%). The upper side of colonies on the PDA plates was milky, and the reverse side was pale yellow at the center and pale white at the margin. After 10 days of growth on the PDA medium, these isolates produced spores separately. . Through electron microscopic observation, conidia were smooth walled, hyaline, aseptate, guttulate, cylindrical with rounded ends with 15 to 20.5 × 5.3 to 6.7 μm (mean 18.5 × 5.8 μm, n = 50) in size. These morphological characteristics were similar to those of the species of Colletotrichumspp (Weir et al. 2012, Fu et al. 2019). To further identify the isolates, the regions of internal transcribed spacer (ITS), actin (ACT), calmodulin (CAL), chitin synthase (CHSI), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and beta-tubulin 2 (TUB2) loci of the three representative isolates (JSJT-1, JSJT-2, and JSJT-3) were amplified and sequenced with the primer pairs ITS-1F/ITS-4, ACT-512F/ACT-783R, CL1/CL2A, CHS-79F/CHS-345R, GDF/GDR and T1/T2 primers, respectively (Weir et al. 2012). Sequences of them were deposited in GenBank under nos. OR214960 to OR214962 (ITS), OR228543 to OR228545 (ACT)，OR228546 to OR228548 (CAL), OR228549 to OR228551 (CHSI), OR228552 to OR228554 (GAPDH), and OR228555 to OR228557 (TUB2). Multilocus phylogenetic analysis revealed that the three isolates and C. aenigma were clustered in the same clade. Based on the results of morphological and molecular analysis, these isolates were identified as C. aenigma. The pathogenicity of three isolates was tested on leaves of pecan seedlings. Suspensions of conidia were obtained by scraping the surface of a 10-day-old sporulated petri dish PDA cultures into sterile water. Suspensions were adjusted to a density of 2 × 106 conidia/ml with a hemocytometer.The conidial suspension of each isolate was sprayed evenly on the surface of leaves from three healthy pecan seedlings. Sterilized distilled water was used for negative controls. The pathogenicity experiment was repeated three times. Finally, all inoculated plants were kept in a light-incubator at 28°C under 100% relative humidity and 12 h photoperiod. Two weeks after inoculation, the inoculated plants developed symptoms similar to those of the original diseased plants, while controls remained asymptomatic. C. aenigma were re-isolated from from inoculated leaves. C. aenigma has been reported as the causal agent of anthracnose on several economically important plants, such as grape ( Kim et al. 2021), tree peonies (Wang et al.2023), chili (Diao et al. 2017), and pear (Fu et al. 2019), but this is the first report of C. aenigma causing anthracnose on pecan in China. Identification of C. aenigma as a pathogen of pecan is important for implementing control management strategies for pecan disease.

Evaluation of outbreak persistence caused by multidrug-resistant and echinocandin-resistant Candida parapsilosis using multidimensional experimental and epidemiological approaches

ABSTRACT Candida parapsilosis is known to cause severe and persistent outbreaks in clinical settings. Patients infected with multidrug-resistant C. parapsilosis (MDR Cp) isolates were identified in a large Turkish hospital from 2017–2020. We subsequently identified three additional patients infected with MDR Cp isolates in 2022 from the same hospital and two echinocandin-resistant (ECR) isolates from a single patient in another hospital. The increasing number of MDR and ECR isolates contradicts the general principle that the severe fitness cost associated with these phenotypes could prevent their dominance in clinical settings. Here, we employed a multidimensional approach to systematically assess the fitness costs of MDR and ECR C. parapsilosis isolates. Whole-genome sequencing revealed a novel MDR genotype infecting two patients in 2022. Despite severe in vitro defects, the levels and tolerances of the biofilms of our ECR and MDR isolates were generally comparable to those of susceptible wild-type isolates. Surprisingly, the MDR and ECR isolates showed major alterations in their cell wall components, and some of the MDR isolates consistently displayed increased tolerance to the fungicidal activities of primary human neutrophils and were more immunoevasive during exposure to primary human macrophages. Our systemic infection mouse model showed that MDR and ECR C. parapsilosis isolates had comparable fungal burden in most organs relative to susceptible isolates. Overall, we observed a notable increase in the genotypic diversity and frequency of MDR isolates and identified MDR and ECR isolates potentially capable of causing persistent outbreaks in the future.

Exploit the study of the scenarios for the control of the response of single-degree-of-freedom systems with bumpers

In earthquake-prone areas, seismic isolation systems are designed to preserve structural safety and prevent occupants’ injury and properties’ damage. However, seismically isolated structures can be subject to large displacements relative to the ground under earthquakes, which lead to define two problems, the first problem concerns to excessive displacements, whereas the second problem relates to excessive accelerations that occur when the displacements are limited by an obstacle with high relative stiffness. An arrangement that favors the solution of these problems is an appropriate interposition between the isolated structure and the obstacle of the shock absorbers or bumpers. The aim of this paper is to investigate, via numerical parametric analyses, the possibility to exploit the occurrence of impact in a two-sided vibro-impact isolated single-degree-of-freedom (SDOF) system under harmonic base excitation with beneficial effects. Through the analysis of the response scenarios which can occur varying the obstacles’ parameters, that is the width of the gap and the mechanical (stiffness and damping) properties, the target is to reduce both the maximum value of the displacement and of the acceleration of the mass, compared to the free flight condition, without possibly reducing the vibration isolation frequency range. This research path leads to the definition of vibro-impacting control systems and to the free and constrained single and multi-objective optimal design of the control system consisting of the integrated assembly of the isolation system, bumpers and gaps. The main results obtained consist in having (i) found a unique optimality condition, (ii) calculated the dissipated energy and given an energetic interpretation to the optimality condition (iii) built maps, that allow to advance behavior predictions, provide indications on the design and allow to make evaluations of the performance of the vibro-impacting system as a function of the stiffness and damping parameters and of the width of the gap. The stiffness ratio and the damping ratio, which define the mechanical properties of the bumpers, are such that the dimensionless relaxation time is about 1, (iv) finally the results are compared to multi-objective optimal design. Ultimately, the advantages of this new isolation system are: (1) provide a physical limit switch to the isolation system in order to limit the maximum displacement of the mass; (2) reduce the effects of amplification dynamics in the resonance zone; (3) reduce the static displacement, all without possibly modifying the dynamic response in the isolation zone.

Bacterial pathogens and antimicrobial resistance in acute otitis media

IntroductionRecent studies show an increase in the prevalence of Haemophilus influenzae and a decrease in Streptococcus pneumoniae among the bacteria that cause acute otitis media (AOM). The objective of our study was to analyse the distribution of pathogens identified in children aged less than 14 years presenting to the emergency department with AOM and their patterns of antimicrobial resistance. Patients and methodsSingle centre retrospective, analytical study in patients aged less than 14 years with a diagnosis of AOM in whom an ear drainage sample was collected for culture in the paediatric emergency department of a tertiary care hospital between 2013 and 2021. ResultsDuring the study period, there were 14 684 documented care episodes corresponding to children with a diagnosis of AOM. An ear drainage culture was performed in 768 of those episodes. The median age of the patients was 2 years, 57% were male and 70% had a previous history of AOM. The most frequently isolated pathogens were: Haemophilus influenzae (n = 188 [24.5%]; 15.5% of them resistant to ampicillin), Streptococcus pyogenes (n = 86 [11.2%]), Staphylococcus aureus (n = 82 [10.7%]), Streptococcus pneumoniae (n = 54 [6.9%]; 9.4% with intermediate resistance to penicillin), Pseudomonas aeruginosa (n = 42 [5.5%]) and Moraxella catarrhalis (n = 11 [1.4%]). No pathogen was isolated in 34.9% of cases. ConclusionsHaemophilus influenzae is the leading cause of AOM in children aged less than 14 years. This, combined with the low frequency of isolation and penicillin resistance of Streptococcus pneumoniae, calls into question the appropriateness of high-dose amoxicillin for empiric treatment of AOM.

Reevaluation of Sensitivity of Monilinia fructicola Isolates to the DMI Fungicide Propiconazole in the Southeastern United States and Investigation of the Genetic Element Mona.

Sterol demethylation inhibitor (DMI) fungicides continue to be essential components for the control of brown rot of peach caused by Monilinia fructicola in the United States and worldwide. In the southeastern United States, resistance to DMIs had been associated with overexpression of the cytochrome P450 14α-demethylase gene MfCYP51 as well as the genetic element Mona, a 65 bp in length nucleotide sequence located upstream of MfCYP51 in resistant isolates. About 20 years after the first survey, we reevaluated sensitivity of M. fructicola from South Carolina and Georgia to propiconazole and also evaluated isolates from Alabama for the first time. A total of 238 M. fructicola isolates were collected from various commercial and two experimental orchards, and sensitivity to propiconazole was determined based on a discriminatory dose of 0.3 μg/ml. Results indicated 16.2, 89.2, and 72.4% of isolates from Alabama, Georgia, and South Carolina, respectively, were resistant to propiconazole. The detection of resistance in Alabama is the first report for the state. All resistant isolates contained Mona, but it was absent from most sensitive isolates. It was unclear if the resistance frequency had increased in South Carolina and Georgia. However, the resistance levels (as assessed by the isolate frequency in discriminatory dose-based relative growth categories) did not change notably, and no evidence of other resistance genotypes was found. Analysis of the upstream MfCYP51 gene region in the resistant isolate CF010 revealed an insertion sequence described for the first time in this report. Our study suggests that current fungicide spray programs have been effective against increasing resistance levels in populations of M. fructicola and suppressing development of new resistant genotypes of the pathogen.

First Report of Pseudocercospora oenotherae Causing Leaf Spot in Rhinacanthus nasutus in China

Rhinacanthus nasutus (L.) Kurz is a traditional Chinese medicine in China. In August 2022, leaf spots were observed on R. nasutus in a Chinese herbal garden in Zhanjiang, Guangdong Province, China (21°17′30″N, 110°18′25″E). Disease incidence was 90% (n = 100 investigated plants from about 800 plants). The yellow spots were round, gray in the center and scattered on the leaves. The coalescence of the individual spot eventually led to leaf wilt. Ten symptomatic leaves from 10 plants were sampled. The margins of the samples were cut into 2 mm × 2 mm pieces. The tissue surface was disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s. Thereafter, the samples were rinsed three times in sterile water, placed on potato dextrose agar (PDA), and incubated at 28 °C. Pure cultures were obtained by transferring hyphal tips to new PDA plates. Twenty-eight isolates were obtained (isolation frequency = 28/4 × 10 = 70%). Three representative single-spore isolates (RNPO-1, RNPO-2, and RNPO-3) by a single-spore isolation method (Fang. 1998) were used for further study. The colonies of isolates on PDA were olive green in 7 days at 28 °C. Conidiogenous cells were unbranched, geniculate–sinuous, tapered toward the apex, and 10 to 20 × 3 μm (n = 20). Conidia were solitary, smooth, straight or curved, pale brown, 3 to 8-septate, apex acute, base truncate, and 50.5 to 88.5 × 2.0 to 3.5 μm (n = 50). For molecular identification, the colony PCR method with Taq DNA polymerase and MightyAmp DNA Polymerase (Lu et al. 2012) was used to amplify the internal transcribed spacer (ITS), translation elongation factor 1-α gene (TEF1), actin (ACT) , and RNA polymerase II second largest subunit (RPB2) loci of the isolates using primer pairs ITS1/ITS4, EF1/EF2, ACT-512F/ACT-783R, and RPB2-7CF/fRPB2-11aR, respectively (O’Donnell et al. 1998; O’Donnell et al. 2010). Their sequences were deposited in GenBank under nos. OP963568 to OP963570 (ITS), OP998376 to OP998378 (TEF1), OP998373 to OP998375 (ACT), and OP998379 to OP998381 (RPB2). By using the Maximum Likelihood method, a phylogenetic tree was generated on the basis of the concatenated data from the sequences of ITS, TEF1, ACT, and RPB2 that clustered the isolates with P. oenotherae (the type strain CBS 131920). The fungus was thus identified as P. oenotherae basing on these morphological and molecular characteristics (Guo and Liu. 1992; Kirschner. 2015). Pathogenicity testing was performed in a greenhouse with 80% relative humidity at 28 °C to 30 °C. Healthy plants of R. nasutus were grown in pots, with one plant in each pot. Sterile cotton balls were immersed in the spore suspension (1 × 105 per mL) of the isolates for about 15 s before they were adhered to the leaves for 3 days. Each isolate was inoculated with three plants (2 month old), and each plant was inoculated with five leaves. Sterile distilled water was as the control and same treatment. The test was performed three times. Symptom were found on the inoculated plants after 2 weeks with the disease incidence 100%, whereas the control plants remained healthy. The fungus was re-isolated from the infected leaves and confirmed as the same isolates by morphological and ITS analyses. No pathogen was isolated from the control plants. P. oenotherae caused leaf spot on Oenothera biennis L. (Guo and Liu. 1992). To the best of our knowledge, this is the first report that R. nasutus is the new host of P. oenotherae (Crous et al. 2013). Thus, this work provides an important reference for the control of this disease in the future.

First report of leaf spot on Chaste-Tree Caused by Alternaria alternata in China.

Chaste-tree (Vitex agnus-castus Linn.) is a perennial ornamental shrub that is native to Europe, which has been widely distributed in China. Since 2021, a serious leaf spot on chaste-tree leaves was observed in Nanjing Botanical Garden, Jiangsu Province, China (31°14'6″N, 118°22'12″E). The disease incidence on the leaves ranged from 20 to 40%. The disease symptom initially appeared as irregular small gray spots on leaves that gradually coalesced into larger lesions with diseased leaves turning black and withering. From August of 2021 to 2022, small pieces of leaf tissues (5×5mm) from the necrotic borders of five typical symptomatic infected leaves were collected and surface sterilized (with 75% ethanol), then incubated in darkness at 25°C for 7 days. A total of fifteen isolates were obtained by monosporic isolation (isolation frequency of 76%). The fungal colonies were initially grayish-white and turned into dark gray with abundant cotton-like aerial hyphae. Microscopic observations revealed light-brown conidia that were obclavate or obpyriform (inversely pear-shaped) with length between 10 and 20 µm (mean 13.3 ± 2.4 µm) and widths between 5 and 10 µm (mean 7.8 ± 1.2 µm), 2 to 4 transverse septa and 0 to 2 longitudinal septa per conidium (n=30) were observed. The fungus was identified as Alternaria alternata based on the colony characteristics (Simmons 2007) and the representative isolate Aa1 was used for further studies. To further identify Aa1, the region of internal transcribed spacer (ITS) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1-alpha (EF-1a) and RNA polymerase second largest subunit (RPB2) genes were amplified from genomic DNA and sequenced with the primer pairs ITS1/ITS4 (Jayawardena et al. 2019), EF-728F/EF-986R (Carbone and Kohn 1999), Gpd1/Gpd2 (Berbee et al. 1999) and RPB2-5F/RPB2-7cR (Liu et al. 1999) respectively. Sequences were deposited into GenBank (Accession No. OQ626644 and OQ630494-OQ630496), which showed 99.2 to 100% sequence homology with those A. alternata strains in GeneBank (ITS, MN394880; GAPDH, MN410920; EF-1a, MN410916; RPB2, MN410918). The multigenes phylogenetic analysis revealed that isolate Aa1 and Alternaria alternata TCS3002 + CBS 916.96 clustered within the same clade with 99% bootstrap support. To test pathogenicity, conidial suspension (1×106 spores/ml) of Aa1 was sprayed uniformly across the leaves of three 1-year-old healthy chaste-tree seedlings; sterilized distilled water sprayed on other trees were used as negative control and the experiment was repeated three times. All inoculated plants were kept in same condition (25°C, under a 16 h/8 h photoperiod and 70% relative humidity). One week later, black/gray spots were observed on the leaves of inoculated plants, similar to the symptoms that were observed on the original diseased plants, while controls remained asymptomatic. Cultures were re-isolated from the infected leaves and were again identified as Aa1 by both morphological characteristics and DNA sequence analysis. The pathogen reported here has a broad host range, and has also been reported on Magnolia grandiflora L. (Liu et al. 2019), Kalanchoe pinnata (Sanahuja et al. 2018) and Kadsura coccinea (Zhang et al. 2020) to cause leaf spot. To our knowledge, this is the first report of A. alternata causing leaf spot disease on chaste-tree and provides an important reference for further biology and epidemiology research.

Isolation and Identification of Pathogenic Bacteria from Hospital Door Handles/knobs

Background and objectives. Contracting infectious diseases from microbial contaminated door handles is a potential threat to health and safety. Therefore, we performed microbiological screening of door handles at the door handles of Zawia Education Hospital, Zawia, Libya, to estimate the presence of potentially pathogenic organisms. Methodology. A total of 125 samples were collected aseptically by using a moistened sterile bacteriologic swab on different days by scrubbing the selected handles and immersing them in the sterile broth to be transported to the microbiology laboratory, within no more than 30 minutes after collection. All the bacterial isolates were characterized and identified by standard diagnostic microbiological procedures and criteria, according to the Clinical and Laboratory Standards Institute. Data were presented as counts and percentages using Excel spread data sheath. Results: There was a total of 147 isolates obtained from the 12 sampled departments. The frequency of isolation of these organisms from these samples was as follows: coagulase-negative staphylococcus (16.80%) in 21 samples, Staphylococcus aureus (10.40%) in 13 samples, Diphtheroid (76.00%) in 95 samples, non-lactose fermenting gram negative bacilli (12.80%) in 16 samples, streptococcus pyogenes (0.80%) in one sample, and Klebsiella pneumoniae (0.80%) in one sample. Conclusion. Staphylococcus aureus, coagulase negative staphylococcus, streptococcus pyogenes, klebsiella pneumonae, Diphtheroid, and non-lactose fermenting gram-negative bacilli were the main bacteria isolated in this research study. The results of the present study demonstrated that contact surfaces such as door handles are often colonized by several bacteria and serve as a potential source of infections.

The role of genetic variants of the SARS-CoV-2 virus in forming of intra-annual increases in the incidence of COVID-19 in Perm Region

BACKGROUND: The causes of intra-annual increases in COVID-19 incidence remain insufficiently studied.
 AIM: This study aimed to investigate the role of genetic variants of SARS-CoV-2 in intra-annual increases of COVID-19 incidence in the Perm region.
 MATERIALS AND METHODS: The monthly dynamics of COVID-19 morbidity and mortality of the population of the Perm region from March 2020 to December 31, 2022 was assessed. The analysis of the monthly frequency of isolation of patients with different genetic variants of SARS-CoV-2 was conducted based on the study results of 2,592 samples from patients in the Perm region performed by specialized laboratories of research institutes in Russia between March 2021 and December 2022. The assessment of the incidence of IgG antibodies to coronavirus among the population was provided according to blood serum studies of 14,006 people.
 RESULTS: In 2020–2022, 4 rises in the incidence of COVID-19 were detected in the Perm region against the background of the emergence of new genetic variants of the pathogen, mainly Alpha, Delta, and Omicron. Increases in COVID-19 incidence and a change in the genetic structure of the pathogen were observed despite an increase in the proportion of people with SARS-CoV-2 IgG in the blood serum. Against the background of the third and fourth increases in morbidity, when the Omicron genotype acquired the leading etiological significance, the infection fatality rate decreased significantly.
 CONCLUSIONS: Intra-annual increases in COVID-19 incidence are largely associated with changes in the genetic structure of the pathogen and are observed despite an increase in the number of people among the population with IgG to SARS-CoV-2 in the blood serum.

Diversity, Composition, and Specificity of the Philaenus spumarius Bacteriome.

Philaenus spumarius (Linnaeus, 1758) (Hemiptera, Aphrophoridae) was recently classified as a pest due to its ability to act as a vector of the phytopathogen Xylella fastidiosa. This insect has been reported to harbour several symbiotic bacteria that play essential roles in P. spumarius health and fitness. However, the factors driving bacterial assemblages remain largely unexplored. Here, the bacteriome associated with different organs (head, abdomen, and genitalia) of males and females of P. spumarius was characterized using culturally dependent and independent methods and compared in terms of diversity and composition. The bacteriome of P. spumarius is enriched in Proteobacteria, Bacteroidota, and Actinobacteria phyla, as well as in Candidatus Sulcia and Cutibacterium genera. The most frequent isolates were Curtobacterium, Pseudomonas, and Rhizobiaceae sp.1. Males display a more diverse bacterial community than females, but no differences in diversity were found in distinct organs. However, the organ shapes the bacteriome structure more than sex, with the Microbacteriaceae family revealing a high level of organ specificity and the Blattabacteriaceae family showing a high level of sex specificity. Several symbiotic bacterial genera were identified in P. spumarius for the first time, including Rhodococcus, Citrobacter, Halomonas, Streptomyces, and Providencia. Differences in the bacterial composition within P. spumarius organs and sexes suggest an adaptation of bacteria to particular insect tissues, potentially shaped by their significance in the life and overall fitness of P. spumarius. Although more research on the bacteria of P. spumarius interactions is needed, such knowledge could help to develop specific bacterial-based insect management strategies.

Transcription levels of hes and their involvement in the biofilm formation of Shiga toxin-producing Escherichia coli O91.

Shiga toxin-producing Escherichia coli (STEC) are recognized as being responsible for many cases of foodborne diseases worldwide. Cattle are the main reservoir of STEC, shedding the microorganisms in their feces. The serogroup STEC O91 has been associated with hemorrhagic colitis and hemolytic uremic syndrome. Locus of Adhesion and Autoaggregation (LAA) and its hes gene are related to the pathogenicity of STEC and the ability to form biofilms. Considering the frequent isolation of STEC O91, the biofilm-forming ability, and the possible role of hes in the pathogenicity of STEC, we propose to evaluate the ability of STEC to form biofilms and to evaluate the expression of hes before and after of biofilm formation. All strains were classified as strong biofilm-forming. The hes expression showed variability between strains before and after biofilm formation, and this may be due to other genes carried by each strain. This study is the first to report the relationship between biofilm formation, and hes expression and proposes that the analysis and diagnosis of LAA, especially hes as STEC O91 virulence factors, could elucidate these unknown mechanisms. Considering that there is no specific treatment for HUS, only supportive care, it is necessary to know the survival and virulence mechanisms of STEC O91.

Effect of COVID-19 on infections associated with medical devices in critical care

ObjectivesThis study explores the hypothesis that COVID-19 patients are at a heightened risk of healthcare-associated infections (HAIs) associated with medical device usage compared to non-COVID-19 patients. Our primary objective was to investigate the correlation between COVID-19 infection in ICU patients and subsequent HAIs following invasive medical device insertion. Additionally, we aim to assess the impact of SARS-CoV-2 infection on onset times concerning specific microorganisms and the type of medical device, providing valuable insights into this intricate relationship in intensive care settings.MethodologyA retrospective cohort study was conducted using ICU patient records at our hospital from 2020 to 2022. This investigation entailed evaluating the timing of HAIs while distinguishing between patients with and without SARS-CoV-2 infection. We identified and analyzed the type of isolation and infection attributed to the medical device while controlling for ICU duration and ventilator days using Cox regression.ResultsOur study included 127 patients without SARS-CoV-2 infection and 140 patients with SARS-CoV-2 infection. The findings indicated a higher incidence of HAI caused by various microorganisms associated with any medical device in patients with SARS-CoV-2 (HR = 6.86; 95% CI-95%: 3.26–14.43; p < 0.01). After adjusting for ICU duration and ventilator days, a heightened frequency of HAIs persisted in SARS-CoV-2-infected individuals. However, a detailed examination of HAIs revealed that only ventilation-associated pneumonia (VAP) displayed a significant association (HR = 6.69; 95% CI: 2.59–17.31; p < 0.01). A statistically significant correlation between SARS-CoV-2 infection and the isolation of S. aureus was also observed (p = 0.034). The prevalence of S. aureus infection was notably higher in patients with SARS-CoV-2 (RR = 8.080; 95% CI: 1.052–62.068; p < 0.01).ConclusionsThe frequency of pathogen isolates in invasive medical devices exhibited an association with SARS-CoV-2 infection. Critically ill patients with SARS-CoV-2 are more prone to developing early-onset VAP than those without SARS-CoV-2 infection.

Bloodstream Infections in Pediatric Oncology Patients: Bacterial Pathogen Distribution and Antimicrobial Susceptibility at the University Hospital Centre Zagreb, Croatia-A 5-Year Analysis.

The epidemiology of bacterial pathogens causing bloodstream infections (BSIs) in pediatric hematology/oncology patients is changing and resistance to antimicrobial agents is globally spread. We retrospectively assessed demographic, clinical, and microbiologic data of BSIs during a 5-year period at a pediatric hematology/oncology unit from January 1, 2017, to December 31, 2021, at the University Hospital Centre Zagreb, Zagreb, Croatia. In 66 pediatric patients with malignancies, 93 BSI episodes were registered and 97 bacterial isolates were cultured. The Gram-positive versus Gram-negative ratio was 67 (69.1%) versus 30 (30.9%). Coagulase-negative staphylococci (48; 49.6%) were the most frequent isolates, followed by Enterobacterales (17; 17.5%) and Staphylococcus aureus (6; 6.2%). Multidrug resistance isolates included extended spectrum β-lactamase producers (n=3). Resistance rates to piperacillin/tazobactam, cefepime, and meropenem in Gram-negative isolates were 15.4%, 14.3%, and 0.0%, respectively. Gram-positive bacteria are the most common cause of BSI in our patients. Resistance rates to piperacillin/tazobactam and cefepime in Gram-negative isolates make meropenem a better choice for empirical antimicrobial treatment. As national and hospital data may differ, the surveillance of pathogen distribution and antimicrobial susceptibility in pediatric hematology/oncology wards is necessary to adjust empirical treatment accordingly.

Comparison of COVID-19 and Non–COVID-19 Patients in Intensive Care Unit for Secondary Infections

Background Bacterial secondary infections were commonly reported in viral respiratory tract infections. However, it is not clear whether there is a difference in the infection rates during the hospitalization in intensive care unit (ICU) caused by COVID-19. The aim of this study was to evaluate the secondary infections in long-term hospitalized patients in the ICU due to COVID-19 and whether COVID-19 increases the tendency to secondary infection in ICU patients. Methods This is a retrospective case-control study. It was conducted in a tertiary care hospital including 34-bed COVID-19 ICU and 20-bed non–COVID-19 ICU. Adult patients in the ICU hospitalized for ≥10 days were included the study. The results of microbiological cultures of blood, urine, and respiratory samples were evaluated in terms of infections during their hospitalization. Results The study group consisted of 51 patients with COVID-19 and the control group consisted of 57 non–COVID-19 patients. There was no significant difference between 2 groups in terms of distribution and frequency of agents isolated from blood culture. The frequency of isolation of Enterobacterales members in urine cultures and nonfermenting bacteria in respiratory samples were significantly higher in non–COVID-19 patients compared with COVID-19 patients (P &lt; 0.05). Conclusions This study revealed that there was no difference among the patients with and without COVID-19 in ICU for the secondary infections when the ICU stay was prolonged. We think that prolonged hospitalization, urinary catheterization, and mechanical ventilation are more important risk factors for secondary infections in ICUs and COVID-19 does not occur an additional risk factor in prolonged ICU stay.

Research on flexible beam-type nonlinear vibration isolators suitable for low frequencies

Ship vibration not only causes safety issues, but also easily generates noise pollution. Therefore, this paper introduces the quasi-zero stiffness (QZS) vibration isolator to solve the problem of low-frequency vibration. In terms of static analysis, this paper proposes a discretized beam constraint model (DBCM) to study the static properties of flexible beams with large deformation, and the finite element analysis (FEA) verifies the accuracy of DBCM. Regarding dynamic analysis, this paper combines the harmonic balance method (HBM) and the pseudo-arc length method (PALM) to analyze the dynamic response and explore the influence of excitation and damping ratio on the response stability. In addition, the performance of equivalent linear isolators is compared, revealing significant advantages of QZS isolator in terms of isolation bandwidth and peak transmissibility. The experimental data demonstrates that QZS isolator’s initial isolation frequency (2.14 Hz) is 68.5% lower than that of linear isolators (6.79 Hz), and the isolation efficiency at 5.35 Hz can reach 90%, making it suitable for low-frequency isolation. Furthermore, experimental data validate the accuracy of the theoretical model and FEA. The static and dynamic theoretical models can optimize the structural parameters of flexible beams and serve as valuable inspiration and reference for designing and improving isolator.