Positive Pathogens Research Articles

Echocardiographic Parameters, Clinical Profile and Presence of Streptococcus pyogenes Virulent Genes in Pharyngitis and Rheumatic Fever

Streptococcus pyogenes is a gram positive pathogen causing pharyngitis, mild infections to chronic complications (Rheumatic Heart Disease, RHD). In this study, echocardiographic and clinical profile in pharyngitis, rheumatic fever patients were compared with virulent genes emm, spe A, spe B and sof. Nearly 107 subjects were classified into Group I – Pharyngitis (n=30), Group II – Rheumatic Fever (n=30) and Group III – healthy controls (n=47). The isolated S.pyogenes from Group I and Group II patient’s throat swab were subjected to 16S rRNA gene sequence. Multiplex PCR was done for identification of virulent genes. Electrocardiogram and Echocardiography was done for all the groups. For statistical analysis ANOVA and t-test were used. Comparison between groups were done by Tukey’s Multiple Comparison test. Among 107 isolates, 16.7% emm gene were detected in Group I and 23.3% in Group II, 56.67 % of spe B in Group I and 73.33 % in Group II, 36.67% of sof gene in Group I and 40% in Group II. Mitral Regurgitation was most commonly encountered in rheumatic fever. Hemoglobin (<0.001) and RDW (<0.001) was significantly lower in Rheumatic Fever whereas Platelet count (<0.001) and Neutrophil (<0.001) was significantly higher when compared with control subjects by Tukey’s Multiple Comparison test. When we compared the genetic relationship with the Echocardiographic findings, presence of one, two or three genes showed moderate to severe regurgitation in Rheumatic Fever subjects.

PH-responsive silica nanoparticles for the treatment of skin wound infections

Chronic wounds are not only a burden for patients but also challenging for clinic treatment due to biofilm formation. Here, we utilized the phenomenon that chronic wounds possess an elevated local pH of 8.9 and developed pH-sensitive silica nanoparticles (SiNPs) to achieve a targeted drug release on alkaline wounds and optimized drug utility. Chlorhexidine (CHX), a disinfectant and antiseptic, was loaded into SiNPs as the model drug. The loaded CHX displayed a release 4 - 5 fold higher at pH 8.0 and 8.5 than at pH 6.5, 7.0 and 7.4. CHX-SiNPs furthermore exhibited a distinctive antibacterial activity at pH 8.0 and 8.5 against both Gram-negative and -positive bacterial pathogens, while no cytotoxicity was found according to cell viability analysis. The CHX-SiNPs were further formulated into alginate hydrogels to allow ease of use. The antibacterial efficacy of CHX-SiNPs was then studied with artificial wounds on ex vivo human skin. Treatment with CHX-SiNPs enabled nearly a 4-lg reduction of the viable bacterial cells, and the alginate formulated CHX-SiNPs led to almost a 3-lg reduction compared to the negative controls. The obtained results demonstrated that CHX-SiNPs are capable of efficient pH-triggered drug release, leading to high antibacterial efficacy. Moreover, CHX-SiNPs enlighten clinic potential towards the treatment of chronic wound infections. Statement of significanceA platform for controlled drug release at a relatively high pH value i.e., over 8, was established by tuning the physical structures of silica nanoparticles (SiNPs). Incorporation of chlorhexidine, an antimicrobial agent, into the fabricated SiNPs allowed a distinctive inhibition of bacterial growth at alkaline pHs, but not at acidic pHs. The efficacy of the SiNPs loaded with chlorhexidine in treating wound infections was further validated by utilizing ex vivo human skin samples. The presented work demonstrates clinic potential of employing alkaline pH as a non-invasive stimulus to achieve on-demand delivery of antimicrobials through SiNPs, showcasing a valuable approach to treating bacterial infections on chronic wounds.

Effectiveness of treatment of bedding and feces of laboratory animal with ozone.

BackgroundThe incineration and burying of the soiled bedding of laboratory animals, as well as using detergents to treat their feces, is hazardous to the environment. This highlights the need for an alternative, environmentally friendly solution for the treatment of the waste of laboratory animal facilities. This study aims to evaluate the efficacy of ozone disinfection of the soiled bedding and feces of laboratory animals.MethodsTwo grams of soiled beddings were randomly sampled from the cages of mice and rats. These samples were mixed in a beaker with 40ml saline. Ozone was piped into the beaker at a concentration of 500mg/h. Samples were taken from the beaker at time 0min, 30min, 45min and 60min after ozone treatment for microbiological culturing in an incubator for 48h. Colony form unit of each plate (CFU/plate) at each time point were counted, the mean CFU/plate at each time point after ozone treatment were compared with that present at time zero. Feces of rabbits and dogs were treated and pathogens were counted the similar way as that of bedding of the mice and rats; samples being taken at 0min, 15min, 30min, 45min and 60min.ResultsPathogens were observed in beddings of both mice and rats as well as in feces of rabbits and dogs. Ozone treatment for 30min killed more than 93% of pathogens in the bedding of the two rodent species and 60min of treatment killed over 99% of pathogens. Treatment of rabbit and dog feces for 30min killed over 96% pathogens present, and 60min’s treatment killed nearly all the pathogens. Both Gram positive and Gram negative pathogens were sensitive to ozone treatment.ConclusionOzone treatment of bedding and feces is an effective and environment friendly way to deal with the waste of animal facilities, saving energy and potentially enabling their reuse as fertilizer.

Clinical and microbiological spectrum of external ventricular drain related infections (EVDRIs) from a tertiary care center.

Background and Objectives:Insertion of an External Ventricular Drain (EVD) is a common and important lifesaving procedure that can lead to morbidity and mortality. This study was conducted to assess the infection rate, risk factors, causative organisms, and outcome of EVDs.Materials and Methods:A prospective study was undertaken in a tertiary care centre from August 1st to October 30th, 2020. Over 192 patients had undergone insertion of EVDs in the neurosurgical intensive care unit. CSF samples were collected in sterile containers and transported to the laboratory.Results:A total of 214 EVDs were inserted in 192 patients for 691 days. The median duration for EVD in situ and the mean time between catheter insertion and onset of infection were 14.5 days and 8 days. EVD related infection rate was 19.4 for 1000 EVD days. The most common risk factor for EVD insertion were tumors (55%) followed by hydrocephalus (40%).We identified 25 patients out of 192 (12%) who had clinical signs and symptoms with deranged CSF counts. A total of 13/25 (52%) specimens were culture positives out of which 10 (76.9%) were Gram negative pathogens and 3 (23%) were Gram positive pathogens and 3/10 (30%) Gram negative pathogens were Multidrug resistant organisms (MDROs).Conclusion:It was observed that longer duration of catheter in situ was an important risk factor for EVD-related infections (ERIs) and also higher frequency of CSF sampling. A proper EVD infection prevention and control protocol must be followed in the form of a checklist at the time of EVD insertion.

Does the COVID Pandemic Modify the Antibiotic Resistance of Uropathogens in Female Patients? A New Storm?

Urinary tract infections (UTIs) represent a common pathology among female patients, leading to overprescribing antibiotics, globally. The emergence of the COVID-19 pandemic has dramatically increased the incidence of this particular viral pneumonia with secondary bacterial superinfection, resulting in continuous therapeutic or prophylactic recommendations of antibiotic treatment; thus, an updated analysis of current antimicrobial resistance among uropathogens is mandatory. This cross-sectional retrospective study conducted in two university hospitals in Bucharest, Romania analyzed 2469 positive urine cultures, among two different periods of 6 months, before and during the COVID-19 pandemic. The most common pathogen was Escherichia coli 1505 (60.95%), followed by Klebsiella spp. 426 (17.25%). Enterococcus spp. was the leading Gram-positive pathogen 285 (11.54%). In gram negative bacteria, in almost all cases, an increased in resistance was observed, but the highest increase was represented by quinolones in Klebsiella spp., from 16.87% to 35.51% and Pseudomonas from 30.3% to 77.41%; a significant increase in resistance was also observed for carbapenems. Surprisingly, a decrease in resistance to Penicillin was observed in Enterococcus spp., but the overall tendency of increased resistance is also maintained for gram positive pathogens. The lack of data on the influence of the COVID-19 pandemic on uropathogens’ resistance promotes these findings as important for every clinician treating UTIs and for every specialist in the medical field in promoting reasonable recommendations of antibiotic therapies.

Physico-chemical and functional characterization of polysaccharide purified from mangrove Rhizophora mucronata leaves having potent biological activity

Rhizophora mucronata Leaves Polysaccharide (RMLP) was extracted and purified from the mangrove Rhizophora mucronata leaves by anion-exchange and size-exclusion column chromatography. Physicochemical characterization of RMLP was evaluated by spectrtoscopic analysis (FT-IR, 1H & 13C NMR) and RP-HPLC. The molecular weight of RMLP was found to be 2.69 kDa, comprised of monosaccharides such as arabinose, galacturonic acid, galactose, mannose, xylose, rhamnose and glucose. The scanning electron microscope (SEM) images showed the appearance of irregular stacks of crystal blocks with a compact structure of RMLP at 5000x fold magnification. The viscosity analysis revealed the pseudoplastic fluid behavior of the polysaccharide with shear-thinning properties. The result of x-ray diffraction (XRD) and Congo red analysis confirmed the semicrystalline nature of RMLP and has triple-helical conformation. Thermal analysis (TGA and DSC) results proved high thermal stability of the RMLP fraction as its degradation temperature was found to be 310 C. The RMLP showed tremendous antibiofilm activity in a dose-dependent manner against the gram positive and gram negative pathogens. The RMLP showed effective antioxidant ability on DPPH scavenging, superoxide, ABTS, hydroxyl anion radical and Fe2+ chelating activities. These findings indicated that RMLP has promising antioxidant and antibiofilm properties against human pathogens, which makes it a better therapeutic agent in the field of functional foods and medicines.

Optimization of cerebrospinal fluid microbial DNA metagenomic sequencing diagnostics

Infection in the central nervous system is a severe condition associated with high morbidity and mortality. Despite ample testing, the majority of encephalitis and meningitis cases remain undiagnosed. Metagenomic sequencing of cerebrospinal fluid has emerged as an unbiased approach to identify rare microbes and novel pathogens. However, several major hurdles remain, including establishment of individual limits of detection, removal of false positives and implementation of universal controls. Twenty-one cerebrospinal fluid samples, in which a known pathogen had been positively identified by available clinical techniques, were subjected to metagenomic DNA sequencing. Fourteen samples contained minute levels of Epstein-Barr virus. The detection threshold for each sample was calculated by using the total leukocyte content in the sample and environmental contaminants found in the bioinformatic classifiers. Virus sequences were detected in all ten samples, in which more than one read was expected according to the calculations. Conversely, no viral reads were detected in seven out of eight samples, in which less than one read was expected according to the calculations. False positive pathogens of computational or environmental origin were readily identified, by using a commonly available cell control. For bacteria, additional filters including a comparison between classifiers removed the remaining false positives and alleviated pathogen identification. Here we show a generalizable method for identification of pathogen species using DNA metagenomic sequencing. The choice of bioinformatic method mainly affected the efficiency of pathogen identification, but not the sensitivity of detection. Identification of pathogens requires multiple filtering steps including read distribution, sequence diversity and complementary verification of pathogen reads.

Structure, surface analysis and bioactivity of Mn doped zinc oxide nanoparticles

Undoped zinc oxide nanoparticles and Mn (5 atomic % & 10 atomic %) doped zinc oxide nanoparticles were prepared by soft chemical method. Antibacterial, antioxidant and anticancer activities in breast cancer cell line MDAMB231 of prepared nanoparticles were investigated. The nanoparticles were characterized using XRD, SEM, EDAX, UV–Vis, FT-IR, and room temperature PL Analysis. Antimicrobial activity was tested against both gram positive and gram negative human pathogens. The antioxidant potential of prepared nanoparticles was estimated using Phosphomolybdate and DPPH assay. The MTT assay was used for cytotoxicity evaluation of prepared nanoparticles against breast cancer cell line MDAMB231. XRD patterns confirmed the nanoparticles were crystallized hexagonal wurtzite structure with an average size of 38.95 ​nm. The absorption wavelength was observed at 361 ​nm in UV–Vis spectrum of Mn (10 atomic %) doped ZnO nanoparticles. The Mn (5 atomic %) doped ZnO nanoparticles exhibited significant antibacterial activity against the gram negative bacteria Escherichia coli, Klebsiella pneumonia at all concentrations. Undoped zinc oxide nanoparticles and Mn doped zinc oxide nanoparticles were effective against the breast cancer cell line MDAMB231.

Broad spectrum of bioactive compounds from halophilic actinomycetes isolated from the Kodiyakadu saltpan of Vedaranyam-India

Discovery of new novel drugs are necessitates for treat the bacterial infectious disease. Since, some potent antimicrobial compounds present in soil actinomycetes. Preliminary study was performed to isolate the halophilic actinomycetes from Kodiyakadu salt pan located in Vedaranyam, Nagapattinam District, Tamilnadu, India for promising antibiotic producing actinomycetes against gram positive pathogens- Stapylocoocus aureus, Streptococcus pneumoniae, Vibrio parahaemolyticus, Enterococus faecalis and gram negative pathogens: Escherichia coli, Salmonella typhi, Klebsiella pneumoniae and pseudomonas aeruginosa. Among the six isolates, there had only one of the strain KOA-2 showed good antibacterial activity. Potential strain was confirmed Streptomyces diastaticus accession no (OM060757) by of 16srRNA sequencing molecular profiling technique. Crude extract of KOA-2 strains shows good pathogenic activity of all pathogens and shows high activity in Vibrio parahaemolyticus (32 mm) zone of inhibition. Resazurin assay MIC value represented 0.05 and MBC value 0.312 expressed in mg ml. Crude extract are characterized by GCMS technique. The increased peak value at (16.775) followed by (22.950) retention time were identified as Carbonic acid, propargyl 2- ethylexyl ester and 1-Decane,3,4-dimethyl bioactive compounds are responsible for antibacterial activity against the bacterial pathogens. Finally, crude extracts of KOA-2 strain are characterized by FTIR, UV analysis, and the results are encouraging for biotechnological techniques.

Characterisation of Clinical Mastitis Occurring in a Dairy Herd of Holstein Friesian Cows

The objective of the present study were to characterize clinical mastitis (CM) occurring in a dairy herd of Holstein Friesian cows located at Agricultural Research and Development Station (ARDS) Simnic-Craiova, Romania (182 m above sea level, 4°19’N and 23°48’E). The severity of CM was classified as grade 1 – when only the milk was abnormal, grade 2 – when abnormal milk was accompanied by swelling or redness of mammary gland and grade 3 – when the cow exhibited systemic signs of illness such as depression, anorexia, dehydration or fever. Only grade 1 and grade 2 of clinical mastitis were analysed in this study. Duplicate quarter milk samples from affected quarters when collected before treatment (Pre-treatment). After the collection, cows were treated using the form protocol. A second set of duplicate quarter milk sample were collected from enrolled quarters at 14 to 21 days after the end of treatment (Post-treatment). Cow level follow-up data was collected for 90 days after the enrolment. Microbiological diagnosis at enrolment included gram-negative, gram-positive and no growth. Data was collected between December 2016 and November 2020, of the 58 cases of CM only 52 cases of grade 1 (n=35) and grade 2 (n=17) were used in analysis. Six cases of CM were of grade 3 (not used in this study). Most causes of CM included in this study were caused by Gram-negative pathogens followed by gram positive pathogens. The common pathogens were E. coli, environmental streptococci Enterobacter spp. and coagulase-negative streptococci. Treatment cure was greater for Gram- negative pathogens. Identification of pathogens causing CM or severity is important in strategic treatment decisions.

Cytocompatible, soft and thick brush-modified scaffolds with prolonged antibacterial effect to mitigate wound infections.

Biomedical device or implant-associated infections caused by pathogenic bacteria are a major clinical issue, and their prevention and/or treatment remains a challenging task. Infection-resistant antimicrobial coatings with impressive cytocompatibility offer a step towards addressing this problem. Herein, we report a new strategy for constructing highly antibacterial as well as cytocompatible mixed polymer brushes onto the surface of 3D printed scaffold made of biodegradable tartaric acid-based aliphatic polyester blends. The mixed brushes were nothing but a combination of poly(3-dimethyl-(methacryloyloxyethyl) ammonium propane sulfonate) (polyDMAPS) and poly((oligo ethylene glycol) methyl ether methacrylate) (polyPEGMA) with varying chain length (n) of the ethylene glycol unit (n = 1, 6, 11, and 21). Both homo and copolymeric brushes of polyDMAPS with polyPEGMA exhibited antibacterial efficacy against both Gram positive and Gram negative pathogens such as E. coli (Escherichia coli) and S. aureus (Staphylococcus aureus) because of the combined action of bacteriostatic effects originating from strongly hydrated layers present in zwitterionic (polyDMAPS) and hydrophilic (polyPEGMA) copolymer brushes. Interestingly, a mixed polymer brush comprising polyDMAPS and polyPEGMA (ethylene glycol chain unit of 21) at 50/50 ratio provided zero bacterial growth and almost 100% cytocompatibility (tested using L929 mouse fibroblast cells), making the brush-modified biodegradable substrate an excellent choice for an infection-resistant and cytocompatible surface. An attempt was made to understand their extraordinary performance with the help of contact angle, surface charge analysis and nanoindentation study, which revealed the formation of a hydrophilic, almost neutral, very soft surface (99.99% reduction in hardness and modulus) after modification with the mixed brushes. This may completely suppress bacterial adhesion. Animal studies demonstrated that these brush-modified scaffolds are biocompatible and can mitigate wound infections. Overall, this study shows that the fascinating combination of an infection-resistant and cytocompatible surface can be generated on biodegradable polymeric surfaces by modulating the surface hardness, flexibility and hydrophilicity by selecting appropriate functionality of the copolymeric brushes grafted onto them, making them ideal non-leaching, anti-infective, hemocompatible and cytocompatible coatings for biodegradable implants.

Phytochemistry and In vitro Antimicrobial Activity of Five Plant Species against Nine Common Human Pathogens

Momordica charantia, Senna podocarpa, Senna alata, Ocimum gratissimum, and Sida acuta which have reportedly been used in folklore for the treatment of various diseases were studied for their antimicrobial activity. Crude methanolic extracts of the leaves were screened for phytochemicals after which they were tested in vitro for activity against clinical isolates of Staphylococcus aureus, Klebsiella oxytoca, Pseudomonas aeruginosa, Proteus vulgaris, Bacillus subtilis, Enterobacter aerogenes, Aspergillus niger, A, flavus and Candida albicans. Phytochemicals present in the extracts included saponins, alkaloids, anthraquinones, tannins, flavonoids and cardiac glycosides. These extracts also showed varying degrees of activity against tested organisms at a concentration range of 15.6 to 500 mg/ml. However, S. acuta showed activity against P. vulgaris, E. aerogenes and As. flavus only. The MIC of the extracts against test organisms ranged from 31.25 to 250 mg/ml. The significant antimicrobial susceptibility of the plant extracts against gram positive bacterial pathogens and some pathogenic yeasts, may not be due to the presence and synergistic interactions of secondary metabolites found in these plant extracts. This would have implications in health, particularly in developing countries where a singnificant percentage of the population are still using traditional plant extracts for health care. Dhaka Univ. J. Pharm. Sci. 20(2): 139-148, 2021 (December)

Evaluation of the BioFire Gastrointestinal Panel to Detect Diarrheal Pathogens in Pediatric Patients.

Infectious diarrhea is a global pediatric health concern; therefore, rapid and accurate detection of enteropathogens is vital. We evaluated the BioFire® FilmArray® Gastrointestinal (GI) Panel with that of comparator laboratory tests. Stool samples of pediatric patients with diarrhea were prospectively collected and tested. As a comparator method for bacteria, culture, conventional PCR for diarrheagenic E. coli, and Allplex GI-Bacteria(I) Assay were tested. For discrepancy analysis, BD MAX Enteric Bacterial Panel was used. As a comparator method for virus, BD MAX Enteric Virus Panel and immunochromatography was used and Allplex GI-Virus Assay was used for discrepancy analysis. The “true positive” was defined as culture-positive and/or positive results from more than two molecular tests. Of the 184 stool samples tested, 93 (50.5%) were true positive for 128 pathogens, and 31 (16.9%) were positive for multiple pathogens. The BioFire GI Panel detected 123 pathogens in 90 of samples. The BioFire GI Panel demonstrated a sensitivity of 100% for 12 targets and a specificity of >95% for 16 targets. The overall positive rate and multiple pathogen rate among patients in the group without underlying diseases were significantly higher than those in the group with hematologic disease (57.0% vs. 28.6% (p = 0.001) and 20.4% vs. 4.8% (p = 0.02), respectively). The BioFire GI Panel provides comprehensive results within 2 h and may be useful for the rapid identification of enteropathogens.

Fabricated silver nanoparticles by a combination of cell-free supernatant of Fusarium solani and Comamonas aquatica and its antibacterial activity

The current study involves silver nanoparticles (AgNPs) synthesis, characterization, and antimicrobial activity of nanoparticles produced by a combination of cell-free supernatant (C-FS) of the intimate organisms, Fusarium solani and Comamonas aquatica as synthesis catalysts against Gram-negative and positive human pathogens. The detailed characterization of the Ag NPs was carried out using UV-visible spectroscopy, field emission Scanning Electron Microscopy (FE-SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). From the UV-visible spectroscopy, the absorption peak was found at 442 nm, and FE-SEM images confirmed the formation of AgNPs. Further, TEM and AFM analysis demonstrated that fabricated AgNPs were relatively monodispersed, approximately spherical, and of the size between 2.0 - 7.5 nm. Furthermore, the antibacterial activity of AgNPs was determined by the agar well diffusion method, and results showed that AgNPs exhibited excellent antimicrobial activity against Gram-negative (E. coli, Pseudomonas aeruginosa, Salmonella enterica) and Gram-positive (Enterococcus faecalis and Staphylococcus aureus). Finally, The MIC test was performed to test the inhibitory concentration of AgNO3 against the bacteria under investigation. This is the first study proposing alternative sources to form AgNPs via synergistic metabolites of F. solani and C. aquatica. The results here offer a foundation for developing an effective therapy using AgNPs against various microorganisms which can endanger human beings.

Cryo-EM Structures of Two Bacteriophage Portal Proteins Provide Insights for Antimicrobial Phage Engineering.

Widespread antibiotic resistance has returned attention to bacteriophages as a means of managing bacterial pathogenesis. Synthetic biology approaches to engineer phages have demonstrated genomic editing to broaden natural host ranges, or to optimise microbicidal action. Gram positive pathogens cause serious pastoral animal and human infections that are especially lethal in newborns. Such pathogens are targeted by the obligate lytic phages of the Salasmaviridae and Guelinviridae families. These phages have relatively small ~20 kb linear protein-capped genomes and their compact organisation, relatively few structural elements, and broad host range, are appealing from a phage-engineering standpoint. In this study, we focus on portal proteins, which are core elements for the assembly of such tailed phages. The structures of dodecameric portal complexes from Salasmaviridae phage GA1, which targets Bacillus pumilus, and Guelinviridae phage phiCPV4 that infects Clostridium perfringens, were determined at resolutions of 3.3 Å and 2.9 Å, respectively. Both are found to closely resemble the related phi29 portal protein fold. However, the portal protein of phiCPV4 exhibits interesting differences in the clip domain. These structures provide new insights on structural diversity in Caudovirales portal proteins and will be essential for considerations in phage structural engineering.

In vitro and in vivo efficacy of green synthesized AgNPs against Gram negative and Gram positive bacterial pathogens

Global threat of mortality and morbidity increasing due to pathogenic bacterial infection and disease become a significant concern for human population. Development of multidrug resistant bacterial pathogens has increased the search of alternative to conventional antibiotics and small molecules. Metallic nanoparticles are rapidly growing in the field of biomedicine, bioremediation, and bioengineering. Metallic nanoparticles synthesized using plant extract gives an upper edge against toxicity and efficacy of the materials. Silver and silver salt is practised in health organization around the world for killing bacterial pathogens. The present study, one-pot synthesized Rubella tuberosa mediated silver nanoparticles (RT-AgNPs) for the inhibition of ESKAPE panel of bacterial pathogens especially Staphylococcus aureus and Pseudomonas aeruginosa. The Minimal Inhibitory Concentration (MIC) of RT-AgNPs was determined as 4 μg/mL against both pathogens, while the Biofilm Inhibitory concentration (BIC) was determined as 4 μg/mL and 16 μg/mL against Gram negative (P. aeruginosa) and Gram positive (S. aureus) pathogens. The synergy of RT-AgNPs with conventional antibiotics showed the better efficacy with Vancomycin and Gentamicin against S. aureus and P. aeruginosa respectively. Further haemolytic activity of RT-AgNPs against human red blood cell confirmed the non-toxicity at the higher concentration of 64 μg/mL. Thus, RT-AgNPs prove to be suitable candidate for the inhibition of biofilm and pathogenicity of Gram negative and Gram positive pathogens.

A preliminary study on the synthesis of biogenic derived hydroxyapatite /medicinal plant extracts composite for potential bone tissue engineering applications

The bone minerals of Hydroxyapatite (Ca10(PO4)6OH2, HAP) are widely utilized in bone repair because of its close similarity to human hard tissues like bone and teeth. HAP has good biocompatible and osteoconductive properties. Naturally derived HAP materials have been widely used in various fields of biomedical applications like filling bones and coating in orthopedics and dental implantation. Hydroxyapatite has considerable mechanical properties, bioactivity, nontoxicity and does not cause any allergic reaction when placed inside the body. To develop an antimicrobial composite for the enhancement of the properties in the tissue engineering applications, HAP powders were prepared by refluxing the cuttlebone (Cb) with diammonium hydrogen phosphate. To the obtained Cb-HAP powders, Carica papaya (Cp) leaf extract was mixed under ultrasonic irradiation techniques to form the Cp induced Cb-HAP composite. Thus, the present work is a preliminary study on the synthesis of Cb-HAP powders and Cp induced Cb-HAP composite for tissue engineering applications. Furthermore, the phase structure and functional group analysis of the prepared composites were investigated through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR). The morphology of the prepared composite was evaluated by using the Scanning electron microscope (SEM). In addition, the antibacterial activities of the composites were investigated against gram positive and gram-negative pathogens such as E. coli and S. aureus through disc diffusion method. From the obtained results, it can be clear that the Cp induced Cb-HAP exhibited enhanced bacterial inhibition. The observed physicochemical and antibacterial activity suggest that the Cp induced Cb-HAP composite can serve as potential biocomposite for bone tissue engineering applications.

156. Evaluation of Trends in Antimicrobial Use and Proportion of Culture Positive Gram-Negative/Gram-Positive Pathogens Comparing Prior to and During the SARS-CoV-2 Pandemic: A Multicenter Evaluation

BackgroundIncreased risk for bacterial co-infections has been described in the pathogenesis of primary viral infections. We evaluated trends in incidence of antibiotic use (abx) and culture positive Gram negative/Gram positive (GN/GP) pathogens in US hospitalized patients prior to and quarterly during the SARS-CoV-2 pandemic.Table. Trends in antimicrobial use, duration, and positive GN/GP pathogen results. MethodsWe conducted a multi-center, retrospective cohort analysis of all hospitalized patients from 241 US acute care facilities with >1-day inpatient admission between 7/1/19-5/15/21 in the BD Insights Research Database (Franklin Lakes, NJ USA). SARS-CoV-2 infection was defined as a positive PCR during or ≤7 days prior to hospitalization. Admissions with abx prescribed ≥24 hrs and a GN/GP non-contaminant, positive culture were evaluated.ResultsDuring the pre-pandemic period (7/19 – 2/20) 30% (600,116/2,001,793) admissions were prescribed abx ≥ 24 hrs and 5.3% were positive for a GN/GP pathogen (Table 1). During the SARS-CoV-2 pandemic, abx use ≥ 24 hrs (66.2%) and positive GN/GP culture (8.4%) was highest in SARS-CoV-2 positive patients followed by patients negative for SARS-CoV-2 (abx ≥ 24 hrs 36.7%; GN/GP pathogens 6.8%), and SARS-CoV-2 not tested (abx ≥ 24 hrs 27.5%; GN/GP pathogens 4.5%). GN/GP positive culture was consistent by quarter during the pandemic for SARS-CoV-2 positive patients, whereas SARS-CoV-2 negative and not tested patients had the highest proportion of antibiotics received and positive pathogens in the first three months of pandemic. SARS-CoV-2 positive patients with positive GN/GP culture had the longest median abx duration. (Table 1) The prevalence of abx usage was highest in all groups for all abx during the early pandemic and then declined over time with the largest declines in SARS-CoV-2 positive patients. (Table 2)ConclusionThis study highlights the impact of viral infections on both prescribing practices and prevalence of bacterial pathogens. Approximately two-thirds of SARS-CoV-2 positive patients received an antibiotic despite a low percentage of positive cultures, however aggregate antimicrobial use overall was similar prior to compared to during the SARS-CoV-2 pandemic. These data may inform opportunities for stewardship programs and antibiotic prescribing in the current and future viral pandemics.Disclosures Laura A. Puzniak, PhD, Merck & Co., Inc. (Employee) Karri A. Bauer, PharmD, Merck & Co., Inc. (Employee, Shareholder) Kalvin Yu, MD, BD (Employee) Vikas Gupta, PharmD, BCPS, Becton, Dickinson and Company (Employee, Shareholder)

221. Evaluation of Rates of Culture Positive Blood Stream Pathogens Prior to and During the SARS-CoV-2 Pandemic: A Multicenter Evaluation

BackgroundBacterial co-infections or super-infections are well-characterized complications of viral infections, further increasing morbidity and mortality of global viral pandemics. We evaluated trends in the incidence of culture positive gram-negative (GN), gram-positive (GP), and fungal/yeast pathogens from a blood source in hospitalized patients at US hospitals before and during the SARS-CoV-2 pandemic.Table: Incidence and rate of blood pathogens in the pre and post SARS-CoV-2 period. Gray indicates significantly lower rate compared to pre-pandemic time period, black indicates significantly higher rates compared to pre-pandemic.Methods: This was a multi-center, retrospective cohort analysis of all hospitalized patients from 267 US acute care facilities with >1-day inpatient admission between 7/1/19-5/19/21 (BD Insights Research Database [Becton, Dickinson and Company, Franklin Lakes, NJ]). SARS-CoV-2 infection was identified by a positive PCR during or ≤7 days prior to hospitalization. All admissions with a non-contaminant culture positive GN, GP, and fungal/yeast pathogen from a blood source were evaluated prior to and during the SARS-CoV-2 pandemic as rates per 1,000 admissions (p< .05 for significance). ResultsThere were 2,001,793 admissions in the pre-SARS-CoV-2 period (7/2019-2/2020) and 2,875,219 admissions during the SARS-CoV-2 pandemic. Incidence of GN/GP blood stream pathogens was significantly higher prior to the SARS-CoV-2 pandemic than during the pandemic. Higher rates of blood stream pathogens occurred in those who were tested for SARS-CoV-2, but all non-tested patients had significantly lower rates than pre-pandemic. Rates of Candida spp., Enterococcus spp., Serratia marcescens, and Enterobacter cloacae were higher in SARS-CoV-2 positive patients compared to pre-pandemic patients. Compared to the prior pandemic period, the incidence of B. fragilis, Streptococcus, Enterococcus and Candida were higher among those tested for SARS-CoV-2 but were negative.ConclusionIn general, rates of positive blood cultures for bacterial pathogens were either lower or similar during the SARS-CoV-2 period compared to the pre-SARS-CoV-2 pandemic period. The patients that were tested for SARS-CoV-2 but were positive who had higher rates of infection than prior may indicate the similarity in viral and bacterial clinical presentation. Further evaluation of higher rates of Enterococcus and Candida in the pandemic period are warranted.Disclosures Laura A. Puzniak, PhD, Merck & Co., Inc. (Employee) Karri A. Bauer, PharmD, Merck & Co., Inc. (Employee, Shareholder) Kalvin Yu, MD, BD (Employee) Pamela Moise, PharmD, Merck (Employee) Vikas Gupta, PharmD, BCPS, Becton, Dickinson and Company (Employee, Shareholder)

Biosynthesis, characterization and antibacterial activity of silver nanoparticles against ESBL producing water-borne pathogens

In the present work, biosynthesis of silver nanoparticles (AgNPs) using isolate of Shigella sp. AS8 culture supernatant as a reducing agent has been demonstrated. Synthesis of AgNPs was completed within 180 min of incubation at 35 °C under bright light condition. The biosynthesized nanoparticles were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Dynamic light scattering (DLS), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray (EDX) and Atomic force microscopy (AFM). The formation of brown color reaction product with strong UV-vis spectrum absorption maxima at 411 nm due to surface plasmon resonance (SPR) indicated the synthesis of AgNPs. FTIR spectrum confirmed association of supernatant protein molecules with synthesized nanoparticles. DLS, TEM, FE-SEM and AFM showed biosynthesized nanoparticles were spherical in shape with an average size of 20 nm. EDX data analysis reveals presence of metallic silver. While, XRD analysis revealed that synthesized particles were pure and crystalline in nature. Further, AgNPs were evaluated as an antibacterial agent against extended spectrum β-lactamase (ESBL) positive water-borne pathogens. The results of present study suggest that biosynthesized AgNPs can be used to combat ESBL producing multidrug resistant bacteria. Copyright © 2016 VBRI Press