Online Advanced Bacterial Identification Software, an Original Tool for Phenotypic Bacterial Identification

The objective of the study is to present and validate an original online Advanced Bacterial Identification Software, ABIS, by comparison to a commercially available, standardized identification system, API strips and apiweb™ bioMerieux software. Methods and results: presentation of ABIS online software, phenotypic bacterial identification of 16 reference strains and 123 wild isolates by ABIS and apiweb TM bioMerieux software and comparative analysis of results. Closed results were obtained (same taxa) for reference and wild strains of Enterobacteriaceae, Pasteurellaceae, Bacillaceae, Lactobacillaceae, Staphylococcaceae, Streptococcaceae, and other. Conclusions: Apiweb™ confirmed the results of ABIS, overall, average identification percent for ABIS being 91.8% and 90.4% for apiweb TM. ABIS online is a powerful tool for microbiology lab and the Encyclopedia connection provides essential information about the ecological significance, pathology and other features of the identified strains.

Identification of the Bacterial Pathogens in Children with Otitis Media: A Study in the Northwestern Portuguese District of Braga

Understanding the bacterial etiology of otitis media (OM) is important when designing and evaluating the best course of treatment. This study analyzed middle ear fluid (MEF) and nasopharynx (NP) samples collected from 49 children with OM undergoing myringotomy in the northwestern Portuguese district of Braga. A correlation between species in the NP and MEF was observed following pathogen detection by culture and quantitative polymerase chain reaction (qPCR) methods. Bacterial identification using culturing methods showed that Moraxella catarrhalis was the most representative in NP and MEF, followed by Streptococcus pneumoniae. However, qPCR of MEF showed a higher prevalence (61%) of Haemophilus influenzae. S. pneumoniae was not the most frequently identified species, but it still remains one of the leading causes of OM in this region despite 93.9% of the children being vaccinated with the pneumococcal conjugate vaccine. Furthermore, 46% of the samples analyzed by qPCR identified more than two bacterial species. M. catarrhalis and S. pneumoniae were the most frequent combination identified in NP and MEF samples by culturing methods. Additionally, a few NP and MEF samples simultaneously presented the three main otopathogens. These results point out that polymicrobial infections play an important role in OM. Further studies characterizing the serotypes of the strains isolated, their resistance profile, and their biofilm forming ability would help in the development of more targeted strategies against otitis media.

Catalase test for bacterial identification v1

Catalase is an enzyme that catalyzes the rapid decomposition of hydrogen peroxide into water and oxygen (2H2O2 + Catalase → 2H2O + O2). Organisms that do not present the catalase enzyme such as group B Streptoccoccus can not degrade hydrogen peroxide and therefore no bubble formation is observed.

Identification of bacteria by poly-aromatic hydrocarbons biosensors

Human health is consistently threatened by different species of pathogenic bacteria. To fight the spread of diseases, it is important to develop rapid methods for bacterial identification. Over the years, different kinds of biosensors were developed for this cause. Another environmental risk are polyaromatic hydrocarbons (PAHs) that may be emitted from industrial facilities and pollute environmental water and soil. One of the methods for their purification is conducted by the addition of bacteria that can degrade the PAHs, while the bacteria itself can be filtrated at the end of the process. Although many studies reported monitoring of the PAHs degradation by fluorescence, not much attention was dedicated to studying the influence of the PAHs on the intrinsic fluorescence of the degrading bacteria. In this work, we apply synchronous fluorescence (SF) measurements to study the ability of the 5 PAHs: 9Antracene carboxylic acid (9ACA), Pyrene, Perylene, Pentacene, and Chrysene to interact with bacteria and change its fluorescence spectra. We show that upon incubation of each PAH with the bacterium E.coli only the 2 PAHs 9ACA and Perylene cause an intensity decrease in the emission at λ = 300 – 375 nm, which derives from the emission of Tyrosine and Tryptophane (TT). Also, we show that upon incubation of 9ACA and Perylene with 5 different pathogenic bacteria, the intensity increase or decrease in the TT emission is unique to each bacterial species. Based on this observation, we suggest that the PAHs 9ACA and Perylene can be utilized as biosensors for bacterial identification.

66. Utilizing ceftazidime/avibactam therapeutic drug monitoring in the treatment of neurosurgical meningitis caused by Difficult-to-treat resistant (DTR)-Pseudomonas aeruginosa and KPC-producing Enterobacterales

Background Central nervous system (CNS) infections caused by carbapenem-resistant Enterobacterales (CRE) and Difficult-to-treat resistant (DTR)-Pseudomonas aeruginosa (PA) are a therapeutic challenge. Data demonstrating the pharmacokinetic/pharmacodynamic (PK/PD) properties of newer beta-lactamase inhibitors remains scarce. A clinical challenge lies in selecting an antimicrobial regimen that diffuses across the blood brain barrier and maintains concentrations to achieve PD targets associated with bacterial killing. These complexities compelled us to quantify the pharmacological properties of ceftazidime/avibactam (CZA). Utilizing therapeutic drug monitoring (TDM), we evaluated the adequacy of therapy and aimed to guide precise CNS dosing in the treatment of three patients with neurosurgical meningitis. Methods Bacterial identification and susceptibility testing were performed using MicroScan. TDM of CZA was implemented using a dose of 2.5 g infused intravenously over 2-hours, every 8 hours. The concentrations of ceftazidime and avibactam were determined by liquid chromatography/mass spectrometry. For patients 2 and 3, four unique CSF and plasma samples spanning the dosing interval were obtained; including trough values. (See table) Results Bacterial identification and CZA MICs for patients 1, 2, and 3 revealed blaKPCKp (0.25μg/mL), DTR PA (4 μg/mL), and blaKPCE. cloacae (0.25 μg/mL), respectively. Measured plasma and CSF concentrations of avibactam (AVI) and ceftazidime (CAZ) are shown in Table 1. Table 1a. Therapeutic Drug Monitoring of CAZ-AVI depicting dosing, time of samples, and measured concentrations in CSF and Human Plasma (HP) Table 1b. Therapeutic Drug Monitoring of CAZ-AVI concentrations in CSF and Human Plasma (HP) pertaining to patient 2 and 3 Conclusion Measuring CZA concentration levels in CSF was achieved in 3 patients with complicated CNS infections. Post-infusion concentrations indicated that adequate CAZ and AVI exposures were attained in the CSF. Notably, avibactam was shown to achieve concentrations ≥1 µg/ml in the CSF throughout the dosing interval. For avibactam and ceftazidime, the PK/PD target correlated with bacterial killing is ~50% fT >MIC. In 2 out of 3 patients, concentrations were determined to be above the respective MICs throughout the entire dosing interval in the CSF. All patients attained clinical and microbiological cure. A novel CZA TDM method was successfully employed to establish that CZA maintains therapeutic CSF concentrations that exceed the MIC throughout the dosing interval. Disclosures Robert A. Bonomo, MD, entasis (Research Grant or Support)Merck (Grant/Research Support)NIH (Grant/Research Support)VA Merit Award (Grant/Research Support)VenatoRx (Grant/Research Support)

Isolation and identification of nitrifying bacteria from tilapia (Oreochromis sp.) pond in Sleman Yogyakarta Indonesia

This research aims to isolate and identify autochtonous nitrifying bacteria from tilapia pond in Sleman Yogyakarta Indonesia for future application in aquaculture practices in the region. Bacteria were isolated using a nitrification medium. Bacterial characterization was carried out by non-pathogenic test to tilapia (Oreochromis sp.), and nitrification activity test in a single bacterial fermentation medium for 9 days. Bacterial identification was carried out based on the colony and cell morphologies, biochemical tests, and molecular analysis using the 16S rRNA and gyrB genes. A total of 15 isolates of nitrifying bacteria were obtained. Four non-pathogenic isolates obtained the highest nitrification activity on the sixth day of incubation, with nitrate production of 17.26-21.54 ppm. Two selected bacteria, isolates A2 and A3, have colony morphology that is milky white, smooth surface, circular shape, entire edge, and convex elevation. Both bacteria are short rods, Gram-negative, non-motile, produce catalase, fermenting glucose, sucrose, and lactose, and do not produce oxidase, ornithine decarboxylase, indole, and H2S. Molecular analysis showed that the two isolates had the highest similarity (99.28% and 99.34%) to Klebsiella spp.

Determination of some virulence factors of Citrobacter freundii isolated from Iraqi patients

This study included the isolation and identification of Citrobacter freundii from 220 samples collected from inpatients and outpatients suffering from urinary tract infection (UTI) and identified at the laboratory of the General Samarra Hospital in Samarra City, Iraq. The study was conducted to investigate some of the virulence factors produced by C. freundii. The results showed that 67 isolates were belonging to the C. freundii, with a rate of 30.45%. Twenty eight samples were from inpatients (41.8%) and 39 samples were from outpatients. The bacterial identification was based on cultural and biochemical tests and confirmed by using VITEK2 compact system. Virulence factor results showed that all isolates were not blood hydrolyzing whereas they produced protease. Seven isolates (10.4%) produced biofilm, five from inpatients and two from outpatients, at rates of 17.8% and 5.1%, respectively. The results showed that 17 (25.4%) of the pathogenic isolates were β-lactamase producers, as determined by the iodometric method, twelve of them (17.9%) were from inpatients and 5 (7.5%) from outpatients. Four isolates of C. freundii produced Extended Spectrum Beta-lactamase (ESβL) enzymes, three from inpatients and one from outpatients, with ratios of 4.5% and 1.4%, respectively. Also, the via B gene, which is responsible for virulence factors, was investigated using PCR. The results showed that 12 isolates from inpatients and 4 isolates from outpatients were harboring this gene. The antimicrobial susceptibility testing by Kirby-Bauer’s method showed that all isolates that produced β-lactamase were resistant to antibiotics.