Short Incubation Period Research Articles

Uji Efektivitas Beberapa Media Tumbuh Alternatif Limbah Organik dengan Penambahan Tepung Kulit Udang terhadap Pertumbuhan Cendawan Entomopatogen Lecanicillium lecanii

Alternative control uses the entomopathogenic fungus Lecanicillium lecanii which is propagated using agro-industrial waste as a substrate for the production of locally available conidia. Propagation of L. lecanii was carried out on media supplemented with shrimp shell flour as additional nutrition. This research aims to provide the best alternative media for the growth of L. lecanii. The research was carried out at the Biological Agents Laboratory (BBPOPT), from March to May 2024. The method used was an experiment with a single factor Completely Randomized Design (CRD). This research consisted of 7 treatments in 4 repetitions: K (Corn Media); A (Sugar Bagasse); B (Tea Dregs); C (Sawdust); D (Sugar Bagasse + Shrimp Shell Flour); E (Tea Dregs + Shrimp Shell Flour); F (Sawdust + Shrimp Shell Flour). The results showed that L. Lecanii has a short incubation period, namely one hsi and alternative organic waste media with the addition of shrimp shell flour is more effectively used in the propagation of the L. lecanii fungus and has a significant effect on colony diameter (8.84 cm) in sawdust + shrimp shell flour. Alternative media with the addition of shrimp shell flour is recommended for the growth of the fungus L. lecanii.

Microcavity Array-Based Digital SERS Chip for Rapid and Accurate Label-free Quantitative Detection of Live Bacteria.

In this study, we developed a novel digital surface-enhanced Raman spectroscopy (SERS) chip that integrates an inverted pyramid microcavity array, a microchannel cover plate, and a multilayer gold nanoparticle (AuNP) SERS substrate. This innovative design exploits the synergistic effects of the microcavity array and the microchannel to enable rapid and large-scale digital discretization of bacterial suspensions. The concentration effect of the picoliter cavities, combined with the superior Raman enhancement effect of the multilayer AuNP SERS substrate, allows for the precise identification of live bacteria within the microcavities through in situ and label-free SERS testing after a short incubation period. By counting the resulting positive or negative signals, the concentration of the target analyte can be directly determined via Poisson statistics. Experimental results demonstrate that this method enables the accurate quantification of Escherichia coli (E. coli) BL21 within a 4-h incubation period. Compared with traditional analog SERS detection methods, our proposed digital SERS detection strategy reduces the impact of signal intensity fluctuations, thereby significantly improving detection efficiency and accuracy. We believe that this digital SERS chip has great application prospects in the fields of bacterial detection, antibiotic resistance analysis, and cellular dynamics monitoring.

Biological Parameters and Feeding Potential of Micromus timidus Hagen (Neuroptera: Hemerobiidae) on Selected Aphid Species

In the present study, we investigated on the developmental biology, adult longevity and fecundity of Micromus timidus Hagen on Aphis craccivora (Koch), Aphis gossypii Glover, Rhopalosiphum maidis (Fitch) and Uroleucon compositae (Theobald) at room temperature (28±20C) and relative humidity of 70%. The study design followed was completely randomized design (CRD). The study was conducted with three replications with 10 larvae in each replication for biology studies and for adult parameters 3 replications with 10 pairs in each replication used. Shortest incubation period, II instar and III instar duration, total larval period, pre-pupal period, and egg to adult period of M. timidus were recorded on A. craccivora, shortest I instar duration was recorded on U. compositae and least pupal period on A. gossypii. The developmental periods for all trait were extended when fed on R. maidis. The reproductive traits viz., oviposition period and adult longevity (male and female) were maximum when M. timidus adults fed on A. gossypii, and the highest fecundity was recorded when fed on A. craccivora. Feeding potential in M. timidus increases progressively across successive instars, with III instar larvae exhibiting the highest aphid predation rate, and first instar larvae displaying the lowest feeding activity. The maximum feeding potential of the larva was noted on A. craccivora (142.47 ± 31.66), while, the adult feeding potential increased when it was given with A. gossypii (1335.10 ± 192.74).

Large invasive herbaceous plants decrease the taxonomic, functional and phylogenetic diversity of birds via their reproductive traits

Abstract Birds are among the organisms most impacted by plant invasions, the effects of which are particularly conspicuous during the breeding season. Birds can incorrectly assess the suitability of large, invasive hogweeds Heracleum sp. in south‐eastern Poland when selecting nesting sites early in spring when the developing invaders do not yet differ substantially in form from the rest of the vegetation. One would expect lower bird breeding success in areas with invasive hogweeds. Furthermore, this may shift bird community composition towards species with filtered traits, which may then be reflected in various measures of diversity. To assess these expectations, we conducted bird surveys at 74 sites, arranged as 37 pairs (with invasive Heracleum vs. control). The presence of Heracleum was associated with lower bird taxonomic and phylogenetic diversity. Functional richness (calculated based on species' reproductive traits) was also lower at sites with these invaders. The species detected at Heracleum sites were characterised by traits associated with rapid breeding, for example, small clutches, short incubation periods and short fledging periods. We show that the bird community at sites with hogweeds became less diverse and composed of random species sharing similar reproductive traits. Bird communities with low diversity at Heracleum sites tended to exhibit a common trait syndrome. These patterns provide insights into the mechanisms of how invasive plants may lead to the loss of some traits and species in bird communities. Read the free Plain Language Summary for this article on the Journal blog.

MNPs-aptazymes-PtNPs molecular motor biosensor mediated by circular cleavage reactions for the ultrasensitive detection of aflatoxin B1 in real samples

As a significant food safety risk factor linked to cancer, liver diseases, and kidney diseases, aflatoxin B1 (AFB1) necessitates rapid and ultrasensitive detection to mitigate its associated high morbidity and mortality rates. In this study, we developed an advanced biosensor for AFB1 detection by optimizing magnetic nanoparticles (MNPs), platinum nanoparticles (PtNPs), and aptazymes. The resulting MNPs-aptazymes-PtNPs molecular motor biosensor demonstrates promising capabilities for AFB1 detection. Initially, the specific binding between AFB1 and a split aptamer pair facilitates the conversion of intermolecular hybridization of DNAzyme strands into intramolecular hybridization on the MNPs surface. Then the catalytic strands of DNAzyme cleave substrate strands, resulting in PtNPs-containing fragments being released from the MNPs surface and enabling the molecular motor’s movement. The extensive cleavage of substrate strands by the long catalytic strands and the stepwise movement on MNPs surface are driven by the target-specific binding of AFB1. With high peroxidase-mimicking activity, the released PtNPs enable AFB1 detection after short incubation period. The MNPs-aptazymes-PtNPs molecular motor exhibits a sensitivity of 98.95 % and a specificity of 100 %, with a minimum detectable concentration of 300 fg/mL. This thermostabilized, cyclic, and enzyme-free nanomachine demonstrates broad applicability for the detection of various aflatoxins due to its target-empowered, sequence-independent mechanism, possesses excellent guarantee and supervision for enormous Ganoderma products in Shandong province, China.

In Silico evaluation of the anti-influenza potential of Streptomyces bioactive compounds

Influenza, a highly contagious respiratory viral disease characterized by its short incubation period and severe symptoms, is treatable with antiviral drugs targeting viremia. Among new antiviral agents, Actinobacteria, particularly from the Streptomyces genus, are notable for their ability to produce potent antiviral compounds. This study evaluates the antiviral potential of Streptomyces sp. KSF 103, isolated from Kuala Sat, Jerantut, Pahang, against the Influenza A virus (IAV). Using molecular docking tools such as AutoDock Vina and PyMOL, the interactions of four compounds – hypoxanthine, vitamin D, purine, and aminocaproic acid – were analyzed against IAV proteins. Vitamin D exhibited the highest binding affinity against H3N2’s M2 (−9.6 kcal/mol) and HA (−9.2 kcal/mol) proteins. Additionally, RMSD dynamics parameters indicated that the best-scoring complexes are predicted to be satisfactorily stable under physiological settings. These findings suggest that Streptomyces sp. KSF 103 could be a promising source for developing new antiviral treatments against influenza.

Effect of human reovirus strain R-92 on tumor cell lines

Background. Among all the new methods and approaches, virotherapy with oncolytic viruses, both in combination with immunotherapy and without it, shows high efficiency in various phases of clinical trials and good tolerance by patients.Aim. To study the sensitivity of some immortalized cancer cell lines to the R-92 strain of human reovirus with cell characteristics at the ultrastructural level.Materials and methods. The study was carried out on cell lines of HeLa, A549, U87MG. Cells were planted in an amount of 15 thousand per well of a 96-well plate and after adhesion, the virus was inoculated by adding a medium containing virus particles in 4 tenfold dilutions (approximately 10 9 –106 particles per ml). Next, the cells were cultured for 24 h, after which the number of living cells in the wells was determined indirectly using the methyl tetrazolium test, which was carried out according to standard methods. To study the ultrastructure of infected cells, cells were seeded into a T25 flask and inoculated with the virus at the maximum concentration. After 24 h of cultivation, the cells were fixed in a 2.5 % glutaraldehyde solution in phosphate buffer for 1 h, after which they were washed three times in phosphate buffer and samples were processed for TEM according to standard methods.Results. Diluting the virus 1000 times led to a decrease in the cytostatic effect in all three cultures to a level practically no different from the control. HeLa turned out to be the most sensitive culture to reovirus. In the experiment, the number of living cells decreased to 60.4 ± 10.2 % compared to the control during incubation with the maximum number of viral particles and to 63.7 ± 16.2 % with a tenfold dilution of the virus. This indicator was significantly lower than in the other two studied cultures under these cultivation conditions (p <0.001).In addition, at the maximum virus concentration, the A549 culture was less sensitive than the U87MG culture (p <0.01). At lower concentrations of viral particles, the average viability of the studied cell lines did not differ significantly from each other. Analysis of electron diffraction patterns showed that the virus successfully replicates in the cytoplasm of the studied cultures, but is not released from the cell, which is apparently due to the short incubation period. TEM also showed cell damage characteristic of apoptosis or necroptosis, uniformly expressed in all studied cultures.Conclusion. Cell lines A549, HeLa and U87MG, according to the results of the methyl tetrazolium test, demonstrate different sensitivity to the human reovirus strain P-92. The TEM picture of cells from infected cultures showed signs of the development of apoptosis or necroptosis.

Monitoring cancer treatments in melanoma cells using a fluorescence lifetime nanoprobe based on a CdSe/ZnS quantum dot functionalized with a peptide containing D-penicillamine and histidine

Anticancer therapies with cisplatin and volasertib (BI-6727) were monitored by fluorescence lifetime imaging microscopy (FLIM) in live SK-Mel-2 melanoma cells. A CdSe/ZnS quantum dot functionalized with a peptide containing D-penicillamine and histidine (CdSe/ZnS-PH) was used as intracellular pH fluorescent probe. A faster cytosol acidification was observed for cells treated with cisplatin when compared to volasertib. The first changes in the intracellular pH were found after 2 hours of treatment with cisplatin and 8 hours with volasertib. Additionally, the relationship between cytosol acidification and apoptosis was investigated using an innovative methodology based on time-resolved fluorescence measurements. Similar low percentages of apoptotic cells were observed after short incubation periods (2 – 8 hours) with both drugs. In contrast, late apoptosis and death were found for a large fraction of cells during 24-hour incubation with cisplatin but not volasertib. Thus, the early acidification observed in cisplatin treatment could accelerate apoptosis and cell death. Despite volasertib treatment shows slower mechanism of action than cisplatin, similar inhibitory effects were found for both drugs at longer incubation periods (72 hours). This study proves the potential of CdSe/ZnS-PH nanoparticle as a fluorescence lifetime probe in the study of the mechanism of action of antitumor drugs.

Validation of short culture method for rapid bacterial identification of blood cultures via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Development of rapid bacterial identification from blood cultures has been an area of intense study in diagnostic microbiology. Shortened turnaround time coupled with antimicrobial stewardship interventions have been shown to improve patient outcomes and decrease healthcare-associated costs. We report the validation of a short incubation method for Gram-positive and Gram-negative bacterial identification utilizing MALDI-TOF MS without additional instrumentation, processing or cost compared with current practice. Prospective, observational, single-centre study in a quaternary care academic hospital encompassing 376 blood cultures subjected to bacterial identification after short incubation periods of 3-4 and 6-8 h. There was 97.5% species-level identification agreement with tests undertaken after 3-4 h incubation with 83.6% isolates identified, and 99.7% species-level identification agreement after 6-8 h incubation with 96.7% isolates identified. The short incubation method provides a rapid MALDI-TOF MS bacterial identification method, reducing turnaround time by 10-18 h compared with standard practice without additional cost, processing or instrumentation.

Brood parasitism and host-parasite relationships: Cuckoos adapt to reduce the time of hatching ahead of host nestlings by increasing egg thickness

The phenomenon of cuckoos’ brood parasitism is well known and can be investigated using applied mathematical techniques. Among adaptive features of this phenomenon are certain egg parameters that ensure their shortened incubation period (I) and thus the successful survival of their offspring. In particular, the volume of a cuckoo egg is not less than, or exceeds, that of the host species, which should, in theory, increase I. Also, cuckoo eggs have thicker shell than that of nest hosts. Here, we analyzed the available geometric dimensions of eggs in 447 species and found an inverse correlation (−0.585, p < 0.05) between I and the shell thickness-to-egg surface area ratio (T/S). A mathematical relationship was derived to calculate I depending on T/S. This premise was confirmed by comparative calculations using egg images of two parasitic species, common (Cuculus canorus) and plaintive cuckoo (Cacomantis merulinus) and their hosts: great reed warbler (Acrocephalus arundinaceus), European robin (Erithacus rubecula), rufescent prinia (Prinia rufescens), and common tailorbird (Orthotomus sutorius). An average calculated I value for cuckoo eggs was one day less than that for host eggs. Our findings unravel additional details of how cuckoos adapt to brood parasitism and specific host-parasite relationships.

Clinical, hematological and some biochemical alterations of Rotavirus group A in newborn buffalo calves

Background: Infectious diarrhea of newborns calves is one of the biggest health problems in beef and dairy industries in Basrah, Iraq, Group A rotavirus considers major cause of gastroenteritis in newborn calve of buffalo in the world, leading to serious economic losses specifically in developing countries. The infection has short incubation period, non-viremic, and profuse diarrhea.Methods: Buffalo calves with diarrhea were carefully examined and a sample of their excrement was collected for this particular study. The calves ranged in age from one to thirty days and were equally split between males and females. We found out whether the calves were girls or boys. The calves' ages were considered throughout the sorting process; they originated from different regions of Iraq's Basrah governorate. Moreover, they were further separated into four separate age groups. Blood samples were collected from calves infected with rotavirus so that the objectives of this research could be fulfilled. Biochemical and hematological studies were the intended purposes of the blood sample collection. Finding out how these samples fared in comparison to the control samples in the group was the next stage. Laboratory diagnostics used real-time polymerase chain reaction (PCR), while field diagnostics used a rotavirus antigen fast test kit. Both techniques were used in tandem.Results: With the use of a field-based rotavirus antigen fast detection kit and real-time polymerase chain reaction, 19 out of 30 samples tested positive for rotavirus antigen. Nineteen out of one hundred samples came back positive. Along with it, the highest infection rates were recorded in January (30.7%) and among children aged five to fourteen (27.5%). The afflicted males and females did not vary significantly from one another statistically. The clinical signs of infected calves were also documented. Symptoms included anorexia with or without a loss of suckling ability, lose or somewhat solid stools, mucous, and a milky or light-yellow color. Some of the other symptoms included signs of dehydration, although to varying degrees. Nothing stood out while comparing the patients' vital indicators. In the infected group, sodium levels dropped significantly, and monocyte and lymphocyte production skyrocketed. If we look at potassium levels, we see that there was no statistically significant difference between the infected and control groups. Infected calves had substantially greater levels of red blood cell count, panel C viral load, hemoglobin B, and total lipid content (TLC) when compared with healthy calves.Conclusion: The study record and suggests the role of rotavirus group A as a serious cause of diarrhea in newborns buffalo calves in Basrah governorate, Iraq.Keywords: Rotavirus; Group A; Buffalo; Basrah Governorate

LOW-TEMPERATURE CALORIMETRIC CHARACTERIZATION OF DEEP EUTECTIC SOLVENTS WITH ADDED WATER

Deep eutectic solvents (DES) are combinations of hydrogen bonds donors and acceptors, characterized by significantly lower freezing temperatures than their components. NADES (with natural, biologically compatible components) are becoming popular for a wide applications variety, for their wide solvent capacities, non-toxicity, biodegradability, and inexpensive components. Applications include new means for bioactive compounds extraction and enzymatic reactions, polymer solubilizing and a variety of physicochemical processes, including those taking place at low temperature. Four DES (β-alanine and DL-malic or citric acid (plus water) and choline chloride and ethylene glycol or glycerol) were investigated by differential scanning calorimetry (DSC) at low temperature. Pure DES behave completely reversibly, proof of physicochemical stability. Alanine-DES present glass transitions between -40 and -80°C. Meanwhile, choline-DES show no thermal events between 0° and -80°C. Increasing water produce glass transitions in all DES at decreasing temperatures, and devitrifications and freezing events. Choline-DES show no effects up to 20% water. However, alanine-DES show strong water effects, possibly phase separation into different water populations. Calcium alginate-sucrose beads were used as structural model for diffusion systems. Beads were incubated in DES (20 min/20 hours) and their low-temperature properties characterized. Short incubation periods were enough to radically alter their thermal behavior.

Comparative evaluation of disease dynamics in wild boar and domestic pigs experimentally inoculated intranasally with the European highly virulent African swine fever virus genotype II strain “Armenia 2007”

Since the reintroduction of African swine fever virus (ASFV) in Europe in 2007 and its subsequent spread to Asia, wild boar has played a crucial role in maintaining and disseminating the virus. There are significant gaps in the knowledge regarding infection dynamics and disease pathogenesis in domestic pigs and wild boar, particularly at the early infection stage. We aimed to compare domestic pigs and wild boar infected intranasally to mimic natural infection with one of the original highly virulent genotype II ASFV isolates (Armenia 2007). The study involved euthanising three domestic pigs and three wild boar on days 1, 2, 3, and 5 post-infection, while four domestic pigs and four wild boar were monitored until they reached a humane endpoint. The parameters assessed included clinical signs, macroscopic lesions, viremia levels, tissue viral load, and virus shedding in nasal and rectal swabs from day 1 post-infection. Compared with domestic pigs, wild boar were more susceptible to ASFV, with a shorter incubation period and earlier onset of clinical signs. While wild boar reached a humane endpoint earlier than domestic pigs did, the macroscopic lesions were comparatively less severe. In addition, wild boar had earlier viremia, and the virus was also detected earlier in tissues. The medial retropharyngeal lymph nodes were identified as key portals for ASFV infection in both subspecies. No viral genome was detected in nasal or rectal swabs until shortly before reaching the humane endpoint in both domestic pigs and wild boar, suggesting limited virus shedding in acute infections.

Embryonic heart rate is higher in species that experience greater nest predation risk during incubation.

Avian eggs develop outside of the female body, and therefore embryonic development is subject to multiple internal (physiological) and external (ecological) factors. Embryonic developmental rate has important consequences for survival. Within species, embryos that develop too quickly often experience deformities, disorders, or mortality, while embryos that develop slowly risk inviability and increase the time they are exposed to various sources of mortality in the nest. These contrasting forces may lead to interspecific variation in developmental rates. We investigated potential factors affecting embryonic heart rate (EHR), a proxy of development, across 14 passerine species in the field. More specifically, we investigated if nest predation risk, clutch size, seasonality, and egg volume influenced EHR. From previous research, we expected, and found, that EHR was positively associated with embryonic age and egg temperature. Species with greater nest predation risk had higher EHR, shorter incubation periods, and lower nest temperature variance. EHR increased as the season progressed and with egg volume, while EHR declined with clutch size. Bird species exhibit varying strategies to increase nestling and fledgling survival in response to predation risk, and these results suggest that variation in embryonic development may be related to species-specific differences in nest predation risk.

Comparatively analyzed pattern of Delta and Omicron SARS-CoV-2 genovariant dominated COVID-19 incidence in the population of the Saratov region

Despite the stable decline in SARS-CoV-2 virus-caused COVID-19 incidence in most countries worldwide by the end of 2023, spreading of this infection on a global scale remains relevant. Among all known SARS-CoV-2 genovariants, within the last about two years Omicron remains dominant. The distinctive properties of this genovariant are presented by short incubation period (1–5 days), high contagiousness, and a relatively mild disease course due to largest number of genomic mutations among all SARS-CoV-2 genovariants. The first case of Omicron genovariant-caused infection in Russia was recorded in early December 2021. Over many month-monitoring after active spread of the genovariant in Russia, it is obvious that in a number of key characteristics it differs profoundly from previous SARS-CoV-2 genovariants. Analyzing major patterns inherent in COVID-19 epidemic process particularly uncovering geographic features is one of the most crucial activities in COVID-19 surveillance. Here, we provide a comparatively analyzed pattern of Delta and Omicron SARS-CoV-2 genovariant dominated COVID-19 incidence in the population of the Saratov region. For this, there was used statistical reporting from the Office of Rospotrebnadzor for the Saratov Region. The main research method is based on epidemiological analysis. The study data showed that upon Omicron genovariant dominance, an increased percentage in COVID-19 cases among children of varying age, increased rate of infected subjects with unknown source of infection as well as improved clinical disease course were recorded. Regardless of the circulating genovariant, elderly people remain to be in risk group. Thus, after three years of the COVID-19 pandemic, the mutual adaptation for SARS-CoV-2 and human population can be observed, which is accompanied by altered biological properties of the former and the accumulation of herd immunity. Alleviated disease symptoms and decreased mortality rate among Omicron genovariant-infected individuals evidence in favor of further COVID-19 transformation into a seasonal infection.

Vector competence of Swedish Culex pipiens mosquitoes for Usutu virus

Usutu virus (USUV) is an emerging mosquito-borne flavivirus with increasing prevalence in Europe. Understanding the role of mosquito species in USUV transmission is crucial for predicting and controlling potential outbreaks. This study aimed to assess the vector competence of Swedish Culex pipiens for USUV. The mosquitoes were orally infected with an Italian strain of USUV (Bologna 2009) and infection rates (IR), dissemination rates (DR), and transmission rates (TR) were evaluated over 7 to 28 days post-infection. The study revealed that Swedish Cx. pipiens are susceptible to USUV infection, with a gradual decrease in IR over time. However, the percentage of mosquitoes with the ability to transmit the virus remained consistent across all time points, indicating a relatively short extrinsic incubation period. Overall, this research highlights the potential of Swedish Cx. pipiens as vectors for USUV and emphasizes the importance of surveillance and monitoring to prevent future outbreaks of mosquito-borne diseases.

Investigation of the effects of in ovo taurine injection on hatching characteristics and stress reduction potential.

In ovo application is the process of administering some nutrients or components into the egg. The main purpose of this application is to ensure that some nutrients are provided to chicks with a short incubation period. Few studies were conducted with taurine in fertile eggs; especially, no observation of hatchability and chick quality has been found. In addition, taurine has an anti-stress impact that fights oxidative factors. To assess the hatchability and chick quality after in ovo taurine administration. To determine the stress that may occur as a result of in ovo application and whether taurine has a stress-reducing effect. A total of 1200 fertile eggs from a 34-week-old broiler breeder (Ross 308) flock were categorized into 4 groups with 75 eggs per replicate: control (uninjected), taurine group (0.30mL dissolved taurine in distilled water), sham control (sterile distilled water) and perforation (eggs perforated and then waxed). On day 14 of incubation, an in ovo injection was administered to the albumen. Data on hatching parameters and hepatic HSP70 levels were obtained using relevant formulas and western blotting, respectively. Control chicks exhibited higher hatchability than other groups, with the taurine group showing the lowest hatchability. The HSP70 levels were the highest in the perforation group compared to the control group. An increase of 21.37% in the taurine group and 83.45% in the sham control group was observed compared to the control group. The findings suggest that in ovo application may induce increased stress, whereas taurine may have positive effects in mitigating the stress caused by in ovo application.

AI-Light Spectrum Replicator (LSR): A Novel Simulated In Situ Lab/On-Deck Incubator

In this communication, we present the prototype of a new simulated in situ lab/on-deck incubator, the light spectrum replicator (LSR), and a method for simulating the measured in situ HOCR light spectrum curves in incubation chambers. We developed this system using AI and genetic algorithms in an iterative fashion to find the best-fitting light spectrum in situ irradiance at different depths. The HOCR light spectrum measured at the depth and time of sampling was processed immediately, so the incubator is in a stable and ready condition by the time the samples inoculated with 14C were placed in sample holders (10 min after sampling). This incubator is intended to provide a reliable, fast, and easy-to-use tool for studying primary production based on the evaluation of the photosynthetic uptake of 14C. This system enables short incubation periods for small samples: we tested incubations of 5 mL samples during 15 min incubation periods. Our initial measurements taken using the prototype revealed a sufficiently good correlation between the on-deck measurements and in situ incubations. This prototype can be improved, as discussed in this text.

Fulminant invasive group A streptococcal infection in children

Group A streptococcal infections dominate among invasive streptococcal infections, with the major causative agent, Streptococcus pyogenes, being quite stable in the environment and bearing a large number of chromosome encoded pathogenicity factors or transmitted by horizontal transfer through bacteriophages. Different genetic variants of S. pyogenes can have a different set of pathogenicity factors able to change during pathogen evolution and determine virulence level for specific isolate. With a short incubation period, the disease can proceed with developing invasive infection and toxic shock syndrome with unfavorable outcome within 7 days from disease onset. The purpose of this article is to increase the doctors’ alertness to early recognition and diagnosis, which directly affects adequate treatment in a timely manner and disease outcome. The data on streptococcal morbidity in Russia and worldwide, review of laboratory diagnostic methods and pathogen genetic typing are presented. The maximum number of cases of streptococcal septicemia in Russia was registered in 2022, which accounted for 69% of all cases during the 2014–2022 observation period. The article also describes two clinical cases of fulminant invasive group A streptococcal infection in children with symptoms of acute respiratory viral infections at the onset of the disease. The results of various laboratory diagnostics methods verifying the diagnosis are presented. The genetic characterization of microbial isolates was performed by deep DNA sequencing. In the biological material from patients (including autopsy in one case), S. pyogenes sequence type ST-28, serotypes emm-1.25 and emm-1.0 were identified. The increasing importance of invasive streptococcal infection for health care in Russia and other countries may be associated with a possible change in dominating S. pyogenes genetic variants. In this regard, the study on circulating S. pyogenes genotypes on an ongoing basis as part of surveillance of streptococcal infection and development of vaccine for specific prevention are required.

Resistance, mechanism, and fitness cost of specific bacteriophages for Pseudomonas aeruginosa.

The bacteriophage is an effective adjunct to existing antibiotic therapy; however, in the course of bacteriophage therapy, host bacteria will develop resistance to bacteriophages, thus affecting the efficacy. Therefore, it is important to describe how bacteria evade bacteriophage attack and the consequences of the biological changes that accompany the development of bacteriophage resistance before the bacteriophage is applied. The specific bacteriophage vB3530 of Pseudomonas aeruginosa (P. aeruginosa) has stable biological characteristics, short incubation period, strong in vitro cleavage ability, and absence of virulence or resistance genes. Ten bacteriophage-resistant strains (TL3780-R) were induced using the secondary infection approach, and the plaque assay showed that vB3530 was less sensitive to TL3780-R. Identification of bacteriophage adsorption receptors showed that the bacterial surface polysaccharide was probably the adsorption receptor of vB3530. In contrast to the TL3780 parental strain, TL3780-R is characterized by the absence of long lipopolysaccharide chains, which may be caused by base insertion of wzy or deletion of galU. It is also intriguing to observe that, in comparison to the parent strain, the bacteriophage-resistant strains TL3780-R mostly exhibited a large cost of fitness (growth rate, biofilm formation, motility, and ability to produce enhanced pyocyanin). In addition, TL3780-R9 showed increased susceptibility to aminoglycosides and chlorhexidine, which may be connected to the loss and down-regulation of mexX expression. Consequently, these findings fully depicted the resistance mechanism of P. aeruginosa to vB3530 and the fitness cost of bacteriophage resistance, laying a foundation for further application of bacteriophage therapy.IMPORTANCEThe bacteriophage is an effective adjunct to existing antibiotic therapy; However, bacteria also develop defensive mechanisms against bacteriophage attack. Thus, there is an urgent need to deeply understand the resistance mechanism of bacteria to bacteriophages and the fitness cost of bacteriophage resistance so as to lay the foundation for subsequent application of the phage. In this study, a specific bacteriophage vB3530 of P. aeruginosa had stable biological characteristics, short incubation period, strong in vitro cleavage ability, and absence of virulence or resistance genes. In addition, we found that P. aeruginosa may lead to phage resistance due to the deletion of galU and the base insertion of wzy, involved in the synthesis of lipopolysaccharides. Simultaneously, we showed the association with the biological state of the bacteria after bacteria acquire bacteriophage resistance, which is extremely relevant to guide the future application of therapeutic bacteriophages.