Determination Of Bacterial Load Research Articles

Correlation Between MTB/RIF Gene Xpert Cycle Threshold Values and Clinical Radiological Severity of Pulmonary Tuberculosis

The determination of bacterial load was essential for assessing disease severity, transmission rate, and prognosis. Gene Xpert is a diagnostic test that provides Cycle Threshold (Ct) value as a potential measure of Mycobacterium Tuberculosis (Mtb) load. Despite its potential, there are limited reports exploring the relationship between Ct value and clinicoradiological severity. This study aimed to correlate Ct value and clinicoradiological severity of pulmonary tuberculosis (TB). The study was a retrospective design using medical record data of confirmed TB patients from January to December 2022. These patients were identified based on Gene Xpert test and classified as high, moderate, or low detection Mtb when Ct value was <16, 16-22, and 22-28, respectively. In assessing the severity of clinical using the Bandim score, thoracic TB lesions was categorized by Chest XRay into minimal, moderate, and advanced. The total of 90 TB patients and the majority were males (78.9%) aged 46-65 years (59.0%), with comorbidities (95.0%). The most of the participants had mild clinical severity (44.4%), with Ct value of 16-22 (52.2%), and moderate lesions (35.6%). The most common lesions were fibroinfiltrates on the chest X-ray (61.1%). The Ct value of <16 had a significant correlation with clinical severity of TB (p<0.05) but no significant association with advanced lesions (p>0.05). Based on the results, Ct value had a strong correlation with clinical severity in pulmonary TB. In addition, it could be used as a predictor for managing pulmonary TB patients and an important indicator for control programs.

Study on the inhibition activity and mechanism of Tanreqing against Klebsiella pneumoniae biofilm formation in vitro and in vivo.

To evaluate the antibacterial effect of Tanreqing (TRQ) against K. pneumoniae and its inhibition activity on bacterial biofilm formation in vitro and in vivo, and to explore the mechanism of the inhibitory effects of TRQ on K. pneumoniae biofilm formation. An in vitro biofilm model of K. pneumoniae was established, and the impact of TRQ on biofilm formation was evaluated using crystal violet staining and scanning electron microscopy (SEM). Furthermore, the clearance effect of TRQ against K. pneumoniae in the biofilm was assessed using the viable plate counting method; q-RT PCR was used to evaluate the inhibitory effect of different concentrations of TRQ on the expression of biofilm-related genes in Klebsiella pneumoniae; The activity of quorum sensing signal molecule AI-2 was detected by Vibrio harveyi bioluminescence assay; Meanwhile, a guinea pig lung infection model of Klebsiella pneumoniae was constructed, and after treated with drugs, pathological analysis of lung tissue and determination of bacterial load in lung tissue were performed. The treatment groups included TRQ group, imipenem(IPM) group, TRQ+IPM group, and sterile saline group as the control. The formation of K. pneumoniae biofilm was significantly inhibited by TRQ in vitro experiments. Furthermore, when combined with IPM, the clearance of K. pneumoniae in the biofilm was notably increased compared to the TRQ group and IPM group alone. q-RT PCR analysis revealed that TRQ down-regulated the expression of genes related to biofilm formation in K. pneumoniae, specifically luxS, wbbm, wzm, and lsrK, and also inhibited the activity of AI-2 molecules in the bacterium. In vivo experiments demonstrated that TRQ effectively treated guinea pig lung infections, resulting in reduced lung inflammation. Additionally, when combined with IPM, there was a significant reduction in the bacterial load in lung tissue. TRQ as a potential therapeutic agent plays a great role in the treatment of K. pneumoniae infections, particularly in combination with conventional antibiotics. And TRQ can enhanced the clearance effect on the bacterium by inhibiting the K. pneumoniae biofilm formation, which provided experimental evidence in support of clinical treatment of TRQ against K. pneumoniae infections.

Immune Cells in the Spleen of Mice Mediate the Inflammatory Response Induced by Mannheimia haemolytica A2 Serotype.

(1) Background: Mannheimia haemolytica (M. haemolytica) is an opportunistic pathogen and is mainly associated with respiratory diseases in cattle, sheep, and goats. (2) Methods: In this study, a mouse infection model was established using a M. haemolytica strain isolated from goats. Histopathological observations were conducted on various organs of the mice, and bacterial load determination and RNA-seq analysis were specifically performed on the spleens of the mice. (3) Results: The findings of this study suggest that chemokines, potentially present in the spleen of mice following a M. haemolytica challenge, may induce the migration of leukocytes to the spleen and suppress the release of pro-inflammatory factors through a negative feedback regulation mechanism. Additionally, an interesting observation was made regarding the potential of hematopoietic stem/progenitor cells congregating in the spleen to differentiate into immune cells, which could potentially collaborate with leukocytes in their efforts to counteract M. haemolytica invasion. (4) Conclusions: This study revealed the immune regulation mechanism induced by M. haemolytica in the mouse spleen, providing valuable insights into host-pathogen interactions and offering a theoretical basis for the prevention, control, and treatment of mannheimiosis.

A Simple In-Vivo Method for Evaluation of Antibiofilm and Wound Healing Activity Using Excision Wound Model in Diabetic Swiss Albino Mice

The study developed a simple and inexpensive method to induce biofilm formation in-vivo for the evaluation of the antibiofilm activity of pharmacological agents using Swiss albino mice. Animals were made diabetic using streptozocin and nicotinamide. A cover slip containing preformed biofilm along with MRSA culture was introduced into the excision wound in these animals. The method was effective in developing biofilm on the coverslip after 24 h incubation in MRSA broth which was confirmed by microscopic examination and a crystal violet assay. Application of preformed biofilm along with microbial culture induced a profound infection with biofilm formation on excision wounds in 72 h. This was confirmed by macroscopic, histological, and bacterial load determination. Mupirocin, a known antibacterial agent effective against MRSA was used to demonstrate antibiofilm activity. Mupirocin was able to completely heal the excised wounds in 19 to 21 days while in the base-treated group, healing took place between 30 and 35 days. The method described is robust and can be reproduced easily without the use of transgenic animals and sophisticated methods such as confocal microscopy.

Assessment of some incipient caries risk factors in adolescents

Relevance. Risk assessment of carious lesion onset remains relevant due to the high incidence rate. The article presents the data on the impact of permanent dental enamel functional condition and microbial factor on incipient caries onset in adolescents.Purpose: The study aimed to investigate the etiology and pathogenesis risk characteristics of incipient caries onset in adolescents.Material and methods. The study included 90 adolescents aged 11-17 y.o. from Penza city. At the clinical stage, we studied adolescents’ permanent teeth vulnerability to caries; then, we formed the study groups according to WHO criteria (Group 1 – moderate, Group 2 – high, Group 3 – the very high intensity of caries) and Group 4 included children of the same age without caries. Vital staining and electric pulp testing with the “DentEst” device (Geosoft, Russia) detected white spot lesions. The OHI-S and enamel acid resistance test (TER-test) evaluated the level of oral hygiene. The laboratory stage determined the number of mixed saliva cells contaminated with bacterial microflora (microflora contamination coefficient) to define the bacterial load in the mixed saliva of the examined adolescents.Results. Besides high clinical rate of white spot lesions (intensity rate 3.10 ± 0.05 and demineralization degree 5.90 ± 0.08 μA) linked to poor oral hygiene level according to OHI-S (2.80 ± 0.13), the examined children of Group 3 (very high caries intensity) revealed a decrease in enamel acid resistance (TER-test 6.50 ± 0.22) and increased bacterial load of mixed saliva – microflora contamination coefficient (48.12 ± 0.80%). Differences with the same parameters in Group 4 (without caries) were statistically significant (P < 0.05). The study of the statistical relationship between enamel demineralization degree and the level of mixed saliva bacterial load (microflora contamination coefficient) detected a positive correlation between the studied parameters of moderate and high power and received the following correlation coefficient values in Group 1 (R = 0.46), 2 and 3 (R = 0.73 and R = 0.78) respectively.Conclusion. Assessment of some risk factors for white spot lesion onset and monitoring of changes may include the analysis of clinical and laboratory data on the hard-dental-tissue condition and mixed saliva bacterial load determination (microflora contamination coefficient).

Pre-treatment and continuous administration of simvastatin during sepsis improve metabolic parameters and prevent CNS injuries in survivor rats

Sepsis causes overproduction of inflammatory cytokines, organ dysfunction, and cognitive impairment in survivors. In addition to inflammation, metabolic changes occur according to the stage and severity of the disease. Understanding the role and place of metabolic disturbances in the pathophysiology of sepsis is essential to evaluate the framework of septic patients, predict the syndrome progress, and define the treatment strategies. We investigated the effect of simvastatin on the disease time course and on metabolic alterations, especially with respect to their possible consequences in the CNS of surviving rats. The animals of this study were weighed daily and followed for 10days to determine the survival rate. In the first experiment, control or cecal ligation and puncture (CLP)-animals were randomized in 24h, 48h, and 10days after septic induction, for bacterial load determination and quantification of cytokines. In the second experiment, control or CLP-animals were treated or not with simvastatin and randomized in the same three time points for cytokines quantification and assessment of their body metabolism and locomotor activity (at 48h and 10days), as well as the evaluation of cytoarchitecture and astrogliosis (at 10days). The CLP-rats treated with simvastatin showed a reduction in plasma cytokines and improvement in metabolic parameters and locomotor activity, followed by minor alterations compatible with apoptosis and astrogliosis in the hippocampus and prefrontal cortex. These results suggest that the anti-inflammatory effect of simvastatin plays a crucial role in restoring energy production, maintaining a hypermetabolic state necessary for the recovery and survival of these CLP-rats.

Utilizing photothermally induced oscillation damping parameters for the determination of bacterial load suspended in microfluidic resonators

Microchannel resonators containing a miniaturized volume of a solution can have various applications in different fields. In this study, a microchannel cantilever was loaded with a solution containing a very small number of Pseudomonas fluorescens bacteria suspended in M9 growth medium. The liquid-filled microchannel cantilever was irradiated with a 532-nm laser. The shift in the frequency of the cantilever due to varying bacterial loads is less reliable; therefore, it could not be used for monitoring the bacterial concentration. The energy loss of the cantilever extracted from the quality factor exhibited reliable results and a very strong correlation with the bacterial concentration. The results showed a linear relation between the damping factor of the cantilever and the bacterial concentration. Accordingly, these findings were expected because the bacteria inside the solution can be considered as particles acting against the cantilever motion due to the solution’s viscosity. Thus, more bacteria caused more damping, in agreement with the experimental observations. A semiquantitative experiment was conducted with a heat source (i.e., laser beam) that focused at the cantilever tip to demonstrate the redistribution of the bacterial load within the solution due to the thermal gradient.

Bacterial load determination of poultry feed with seasonality effect in Karachi, Pakistan.

Background: The escalating rate of food-borne diseases via poultry feeds necessitates the characterization of the pathogens to reduce the health risk factor for humans and animals. The poultry feed microbial analysis help to control food-borne illness. In addition, the knowledge about seasonal effects on microbial growth helps the manufacturers to take precautionary measures in alarming months to maintain the standard quality of poultry feed.
 Methodology: This study was designed to identify and enumerate bacteria and their seasonal variation. Total feed samples (n=204) were evaluated through traditional culture techniques, microscopic inspection, and biochemical properties. However, bacterial load was determined by using the total viable count.
 Results: As a result, five genera, including Salmonella enterica (39.05%), Escherichia coli (22.48%), Bacillus subtilis (18.34%), Staphylococcus aureus (11.24%), and Streptococcus sp (8.87%), were isolated. The proportion of occurrence of the bacterial load was lowest in December-February (64.4%) and highest in June-August (96.2%). Whereas in September-November was (87.6%) and March-May (77.5%). On the whole, the total percentage of positive samples was 82.8%. Statistical analysis revealed that (9.9×10-8 cfu/g) was the highest viable bacterial count recorded from June to August. The presence of food-borne pathogens, especially S.enterica and E.coli, is bothersome. Moreover, June to August is considered the most troubling month due to the elevated level of contamination.
 Conclusion: To evade microbial contamination, the microbiological security rules must be followed throughout the process of formulation and storage period, especially in sensitive hot and humid months of June to August. Also, standard inspection should be taken to control the dissemination of food-borne illness.

Characterization of Bacterial Populations in Urban and Rural Houston Watershed Soil Samples Following a Flooding Event

Since Houston is prone to flooding events, bacterial population dynamics in Houston watershed soils pre- and post-Hurricane Harvey were evaluated. Unexpectedly, bayous closer to Houston’s urban core, including Buffalo, Halls, Mustang, and Horsepen Bayous, had significantly higher enteric bacterial loads during the winter than the summer, likely due to water flow rate changes or proximity to wastewater outflow. Following bacterial load determination, isolated colonies were identified using biochemical tests. Additionally, metagenomic sequencing of 16S rDNA allowed for identification of both culturable and unculturable organisms. The phyla Proteobacteria, Actinobacteria, Bacteriodetes and Firmicutes were found to be dominant in our metagenomic analysis and are human gut bacteria. Some opportunistic bacterial Proteobacteria pathogens identified in our metabolomic analysis were Serratia marcenscens, Pseudomonas mendocina, Pseudomonas fulva, and Pseudomonas putida. To our knowledge, this is the first study that compares Houston-area bacterial populations before and after a major flooding event. Taken together, Hurricane Harvey likely contributed to a redistribution of enteric bacteria, as there was a significant increase in the enteric population of Buffalo and Halls Bayous. Similarly, our 2018 winter data set followed the same trend, as significant increases were seen in the enteric populations of Horsepen, Mustang, and Cypress Creek watershed soils.

Application of the Micro Biological Survey analytical method for the determination of bacterial load in cow raw milk.

The aim of this study was to evaluate the performance of “Micro Biological Survey – MBS Test” in the enumeration of bacterial load in cow raw milk. The MBS test is based on a colorimetric method recently developed and patented by “Roma Tre” University, Italy. The evaluation of the performance of the MBS method was carried out by comparison with plate count at 30°C (gold standard) and flow cytometry. Thirteen independent set of experiments were performed analyzing a total of 104 samples of cow raw milk with the selected methods. Results obtained using the MBS method are comparable with those obtained with the plate count method at 30°C (CFU/mL) and flow cytometry technology; in particular, the results obtained with the MBS method are very close to plate count’s at 30°C. On the other hand, there are statistically significant differences between these two methods’ and flow cytometry technology’s results that could be due to the different experimental conditions.

Peptidylarginine Deiminases 2 Mediates Caspase-1-Associated Lethality inPseudomonas aeruginosaPneumonia-Induced Sepsis

Pseudomonas aeruginosa (PA) is a pathogenic bacterium that causes severe pneumonia in critically ill and immunocompromised patients. Peptidylarginine deiminase (PAD) 2, PAD4, and caspase-1 are important enzymes in mediating host response to infection. The goal of this study was to determine the interplay between PAD2, PAD4, and caspase-1 in PA pneumonia-induced sepsis. Pneumonia was produced in wild-type, Pad2-/-, and Pad4-/- mice by intranasal inoculation of PA (2.5 × 106 colony-forming units per mouse), and survival (n = 15/group) was monitored for 10 days. Bone marrow-derived macrophages (BMDMs) were isolated for in vitro studies. Samples were collected at specific timepoints for Western blot, bacterial load determination, and flow cytometry analysis. Caspase-1-dependent inflammation was diminished in PA-inoculated Pad2-/- mice, contributing to reduced macrophage death and enhanced bacterial clearance. In addition, Pad2-/- mice exhibited improved survival and attenuated acute lung injury after PA infection. In contrast, Pad4-/- mice did not display diminished caspase-1 activation, altered bacterial loads, or improved survival. Peptidylarginine deiminase 2 plays an essential role in the pathogenesis of pulmonary sepsis by mediating caspase-1 activation. This goes against previous findings of PAD4 in sepsis. Our study suggests that PAD2 is a potential therapeutic target of PA pneumonia-induced sepsis.

Specific PCR and Quantitative Real-Time PCR in Ocular Samples from Acute and Delayed-Onset Postoperative Endophthalmitis

Rapid identification of virulent pathogens is essential to strengthen the therapeutic strategy of acute endophthalmitis. This study sought to compare the contribution of a combination of polymerase chain reaction (PCR)-based tests to culture methods, in patients with postoperative endophthalmitis. Prospective multicenter study diagnostic evaluation. Setting: university referral centers. 153 consecutive patients presenting with acute or delayed-onset postoperative endophthalmitis, between 2008 and 2015. There were a total of 284 aqueous humor (AH) and/or vitreous fluid (VF) samples. Outcomes and measurements: microbiological tests of intraocular samples included bacterial culturing of pediatric blood culture bottles; 16SrDNA amplification and sequencing (panbacterial PCR) for detection and identification of all bacterial species; real-time PCR (qPCR) assays targeting the femA or lytA gene for detection of Staphylococcus aureus (S. aureus) or Streptococcus pneumoniae (S. pneumoniae), respectively; and a qPCR assay targeting the tuf gene for detection and quantification of Staphylococcus epidermidis (S. epidermidis). At the time of admission, the rate of detection of microorganisms by PCR-based tests was not significantly different than that by culturing (38% versus 30% in AH samples [n= 69]; 66% versus 63% in VF samples [n= 82], respectively). In contrast, after 1 intravitreal injection (IVI) of antibiotics, the identification rate by PCR-based tests was higher than that in VF by culturing (62% vs 48%, respectively; n= 94; P= 0.05). Bacteria were identified in 70% of patients, with a predominance of Gram-positive bacteria (93%). Specific qPCR tests targeting S. aureus and S. pneumoniae did not provide additional diagnoses but provided earlier results. The S. epidermidis load in vitreous at the time of patients' admission was higher in cases of final visual acuity (VA) of <20/40 (127,118 ± 125,848 DNA copies/mL) in patients with a VA of ≥20/40 (40350,000 ± 46,912 DNA copies/mL; P= 0.09). No significant changes in S. epidermidis load was found after one IVI. Patients with acute or delayed-onset endophthalmitis should benefit from microbiological identification in vitreous samples by combined analysis using bacterial cultures in pediatric blood culture bottles and panbacterial PCR. The last test was more effective than cultures in vitreous samples collected after an IVI of antibiotics. The qPCR tests targeting S. aureus and S. pneumoniae gave earlier results than culture and panbacterial PCR but did not provide additional diagnoses. As for S. epidermidis infections, determination of bacterial load using the qPCR test targeting the tuf gene could help evaluation of the visual prognosis of patients. Its role in the follow-up of patients after antibiotic treatment needs further investigation.

Preparation and preclinical evaluation of two novel Staphylococcus aureus capsular polysaccharide 5 and 8-fusion protein (Hla-MntC-SACOL0723) immunoconjugates.

Staphylococcus aureus is one of the most common pathogens in the hospital and the community. The emergence of broad-spectrum antibiotic resistance in S. aureus has made the treatment process more difficult. Therefore, it is obvious that an effective prevention strategy against the pathogen could significantly reduce costs related to care in hospitals. In this report, we describe a simple approach to conjugate S. aureus capsular polysaccharide 5 (CP5) from S. aureus Reynolds strain and 8 (CP8) from S. aureus Becker strain to a fusion protein (Hla-MntC-SACOL0723) and investigation of its bioactivity. The conjugation was done by using ADH (as a bridge) and EDAC (as a coupling agent). The immunoconjugates were characterized by routine polysaccharide/protein contents assays followed by reverse phase chromatography and FTIR spectroscopy. The groups of mice were immunized with conjugate vaccines, capsular polysaccharides, and phosphate-buffered saline (PBS) as a control group. The functional activity of the vaccine candidates was evaluated by ELISA, opsonophagocytosis tests, and determination of bacterial load in challenge study. The results showed that the specific antibody (total IgG) titers raised against conjugate molecules were higher than those of the nonconjugated capsular polysaccharides. The opsonic activity of the conjugate vaccines antisera was significantly higher than polysaccharides alone (58% reduction in the number of bacteria versus 16.3% at 1:2 dilution, p < .05), Further, the conjugate vaccine group had a significant reduction in bacterial load after challenge with S. aureus COL strain cells as compared to the PBS and nonconjugated controls. In conclusion, the immunoconjugates could be developed as a potential vaccine candidate against S. aureus.

Spatial Network Mapping of Pulmonary Multidrug-Resistant Tuberculosis Cavities Using RNA Sequencing.

Rationale: There is poor understanding about protective immunity and the pathogenesis of cavitation in patients with tuberculosis.Objectives: To map pathophysiological pathways at anatomically distinct positions within the human tuberculosis cavity.Methods: Biopsies were obtained from eight predetermined locations within lung cavities of patients with multidrug-resistant tuberculosis undergoing therapeutic surgical resection (n = 14) and healthy lung tissue from control subjects without tuberculosis (n = 10). RNA sequencing, immunohistochemistry, and bacterial load determination were performed at each cavity position. Differentially expressed genes were normalized to control subjects without tuberculosis, and ontologically mapped to identify a spatially compartmentalized pathophysiological map of the cavity. In silico perturbation using a novel distance-dependent dynamical sink model was used to investigate interactions between immune networks and bacterial burden, and to integrate these identified pathways.Measurements and Main Results: The median (range) lung cavity volume on positron emission tomography/computed tomography scans was 50 cm3 (15–389 cm3). RNA sequence reads (31% splice variants) mapped to 19,049 annotated human genes. Multiple proinflammatory pathways were upregulated in the cavity wall, whereas a downregulation “sink” in the central caseum–fluid interface characterized 53% of pathways including neuroendocrine signaling, calcium signaling, triggering receptor expressed on myeloid cells-1, reactive oxygen and nitrogen species production, retinoic acid–mediated apoptosis, and RIG-I-like receptor signaling. The mathematical model demonstrated that neuroendocrine, protein kinase C-θ, and triggering receptor expressed on myeloid cells-1 pathways, and macrophage and neutrophil numbers, had the highest correlation with bacterial burden (r > 0.6), whereas T-helper effector systems did not.Conclusions: These data provide novel insights into host immunity to Mycobacterium tuberculosis–related cavitation. The pathways defined may serve as useful targets for the design of host-directed therapies, and transmission prevention interventions.

Effects of resveratrol on shedding and pathological dynamics in experimental B. melitensis infection in dexamethasone-treated nonpregnant Boer goats

ABSTRACT Brucellosis constitutes an infectious re-emerging zoonosis. Spread of diseases could be exacerbated by stress-induced immunosuppression. This study evaluated relationship between Brucella melitensis infection, shedding dynamics, dexamethasone-induced stress, pathological alterations and resveratrol ameliorative effects in goats. Twelve nonpregnant goats were divided into four groups A, B, C, and D of three animals each. Groups A and B were administered 107 CFU/mL of B. melitensis ocularly, 21 days prior to 7 days consecutive administration of dexamethasone (2 mg/kg). Group A was further administered resveratrol (5 mg/kg) intravenously for 5 consecutive days from day 31 post B. melitensis inoculation. Group C was administered similar dose of B. melitensis while group D was inoculated normal saline. Blood, nasal, ocular, and vaginal swabs were collected at intervals for analysis. The does were sacrificed at day 42 post inoculation (pi). Tissues were collected for tissue bacterial load determination, histopathology, and immunohistochemistry. Dexamethasone administration from day 21 pi increased the frequency in the shedding dynamics, tissue bacterial load, pathological alterations (frequency of microgranuloma and intensity of immunostaining) in group B while 5 days treatment with resveratrol following dexamethasone administration significantly reduced tissue bacterial load, decline in shedding dynamics, and ameliorate damage by dexamethasone administration/B. melitensis infection.

Optimisation of the Protocol for the LIVE/DEAD® BacLightTM Bacterial Viability Kit for Rapid Determination of Bacterial Load.

Rapid antimicrobial susceptibility testing is needed to reduce prescription of inappropriate antibiotics. A rapid alternative to standard culture-based testing is to determine reductions in cell viability using the LIVE/DEAD® BacLightTM Bacterial Viability Kit. We optimised the kit protocol for this application, focusing on simplifying the process by minimising the steps involved and on determining the optimal analytical parameters for fluorescence measurements from the dyes SYTO 9 and propidium iodide (PI). We demonstrate that for our experimental system, the intensity of emissions should be integrated from 505–515 nm for SYTO 9 and 600–610 nm for PI, and the proportion of live cells calculated from a new dye ratio formula, termed the adjusted dye ratio. We show that the pre-staining washing step is not necessary if a non-fluorescent growth media is used; however, staining must be done for each sampling as prolonged exposure to the dyes negatively impacts cell viability. The optimised methodology was able to reproducibly detect reductions in culture viability when the proportion of live cells in a sample of 1 × 108 cells/ml fell below ∼50% live in a media that supports the growth required for detecting antibiotic killing. Finally, we show that the interaction of fluorescence emission spectra from SYTO 9 and PI stained Escherichia coli cells is influenced by the proportion of dead cells in a sample. The excitation of PI by SYTO 9 was found to occur in populations containing sufficient numbers of dead cells (>25%), whereas in populations with low numbers of dead cells the dye interaction was additive in regard to red emissions, indicating that these dye interactions may offer another dimension to live/dead analysis. Fluorescence measurements from samples established according to the optimised protocol can be taken using a flow cytometer, spectrofluorometer, microplate reader, and the Optrode, a fibre-based spectroscopic system developed at the University of Auckland.

Bacterial load determination and potentially pathogenic bacteria detection from air conditioning filter samples collected from domestic environments in Mexico’s northeast region.

Los patógenos en aire pueden afectar la salud humana, no solo por infecciones, sino causando respuestas alérgicas o efectos tóxicos. Estos microorganismos pueden encontrar un ambiente ideal de desarrollo en unidades de aire acondicionado y aunque existen innovaciones para un flujo de aire más limpio y saludable, usuarios en países en desarrollo tienen modelos anteriores o carecen de una rutina de limpieza adecuada de filtros empleados, representando un peligro para poblaciones vulnerables que pasan mucho tiempo en ambientes climatizados. Por esto, nuestro objetivo fue detectar mediante métodos microbiológicos y moleculares la presencia de patógenos en muestras de Tamaulipas, México. Nuestros hallazgos muestran una carga bacteriana media superando las 2,300,000 UFC (unidades formadoras de colonia) /g, β-hemólisis en más del 20% de los cultivos en agar sangre, crecimiento en medios selectivos para Staphylococcus sp. y Enterobacteriaceae en más del 50% de las muestras, esta última confirmada por ensayos moleculares, los cuales también mostraron una baja prevalencia de genes relacionados con resistencia a antibióticos. Estos resultados nos indican que el polvo acumulado en las rejillas de aires acondicionados puede efectivamente ser reservorio de bacterias con capacidad patogénica

Standardisation is necessary in urogenital and extragenital Chlamydia trachomatis bacterial load determination by quantitative PCR: a review of literature and retrospective study

ObjectivesPathogen load has been linked to disease severity in patients infected with HIV, resulting in international standards to adequately and reproducibly quantify load. Chlamydia trachomatis (CT) load has been inconsistently...

Indoor bacterial load and its correlation to physical indoor air quality parameters in public primary schools

Background: Poor indoor air quality is a great problem in schools due to a high number of students per classroom, insufficient outside air supply, poor construction and maintenance of school buildings. Bacteria in the indoor air environment pose a serious health problem. Determination of bacterial load in the indoor environment is necessary to estimate the health hazard and to create standards for indoor air quality control. This is especially important in such densely populated facilities like schools. Methods: Institutional based cross-sectional study was conducted among 51 randomly selected classrooms of eight public primary schools from March 29–April 26, 2018. To determine the bacterial load passive air sampling settle plate method was used by exposing a Petri dish of blood agar media for an hour. The Pearson correlation matrix was employed to assess the correlation between bacterial load and physical parameters. Results: The grand total mean bacterial load was 2826.35 CFU/m3 in the morning and 4514.63 CFU/m3 in the afternoon. The lowest and highest mean bacterial load was recorded at school 3 (450.67 CFU/m3) and school 5 (7740.57 CFU/m3) in the morning and afternoon, respectively. In the morning relative humidity (r = −0.7034), PM2.5 (r = 0.5723) and PM10 (r = 0.6856); in the afternoon temperature (r = 0.3838), relative humidity (r = − 0.4014) were correlated with indoor bacterial load. Staphylococcus aureus, Coagulase-negative Staphylococcus species and Bacillus species were among isolated bacteria. Conclusions: High bacterial load was found in public primary schools in the Gondar city as compared to different indoor air biological standards. Temperature, relative humidity and particulate matter concentration (PM2.5 and PM10) were associated with the indoor bacterial load. Staphylococcus aureus, Coagulase-negative Staphylococcus species and Bacillus species were among isolated bacterial species. Attention should be given to control those physical factors which favour the growth and multiplication of bacteria in the indoor environment of classrooms to safeguard the health of students and teachers in school.

Indoor bacterial load and its correlation to physical indoor air quality parameters in public primary schools

BackgroundPoor indoor air quality is a great problem in schools due to a high number of students per classroom, insufficient outside air supply, poor construction and maintenance of school buildings. Bacteria in the indoor air environment pose a serious health problem. Determination of bacterial load in the indoor environment is necessary to estimate the health hazard and to create standards for indoor air quality control. This is especially important in such densely populated facilities like schools.MethodsInstitutional based cross-sectional study was conducted among 51 randomly selected classrooms of eight public primary schools from March 29–April 26, 2018. To determine the bacterial load passive air sampling settle plate method was used by exposing a Petri dish of blood agar media for an hour. The Pearson correlation matrix was employed to assess the correlation between bacterial load and physical parameters.ResultsThe grand total mean bacterial load was 2826.35 CFU/m3 in the morning and 4514.63 CFU/m3 in the afternoon. The lowest and highest mean bacterial load was recorded at school 3 (450.67 CFU/m3) and school 5 (7740.57 CFU/m3) in the morning and afternoon, respectively. In the morning relative humidity (r = − 0.7034), PM2.5 (r = 0.5723) and PM10 (r = 0.6856); in the afternoon temperature (r = 0.3838), relative humidity (r = − 0.4014) were correlated with indoor bacterial load. Staphylococcus aureus, Coagulase-negative Staphylococcus species and Bacillus species were among isolated bacteria.ConclusionsHigh bacterial load was found in public primary schools in the Gondar city as compared to different indoor air biological standards. Temperature, relative humidity and particulate matter concentration (PM2.5 and PM10) were associated with the indoor bacterial load. Staphylococcus aureus, Coagulase-negative Staphylococcus species and Bacillus species were among isolated bacterial species. Attention should be given to control those physical factors which favour the growth and multiplication of bacteria in the indoor environment of classrooms to safeguard the health of students and teachers in school.