Susceptibility Of Microorganisms Research Articles

Investigation on micro-bubble flotation and coagulation for the treatment of anaerobically treated palm oil mill effluent (POME)

The rapid expansion of the palm oil industry has led to the generation of large volumes of POME in Malaysia. Most conventional aerobic processes for post-treatment of POME are unable to consistently meet environmental discharge standard due to the susceptibility of microorganisms to variable climatic conditions. The main aim of this study was to investigate the potential use of micro-bubbles generated from a venturi tube and the coagulation with polyaluminium chloride (PAC) as a post-treatment method for POME. The micro-bubbles generated from the venturi are capable of removing 57.3% of total suspended solid (TSS) and 74.5% of oil and grease (O&G) and improve the chemical oxygen demand (COD) by 53.7% and biochemical oxygen demand (BOD) by 77.0% with a bubbling time of 12.5 min and a flow rate of 19.8 L/min. However, a single-stage micro-bubble flotation is unable to treat the POME to meet environmental discharge standard. Thus, different PAC coagulant dosage are investigated and the optimum dosage is 2 g/L resulting in at least 93% of COD removal.

Energy metabolism and drug efflux in Mycobacterium tuberculosis.

The inherent drug susceptibility of microorganisms is determined by multiple factors, including growth state, the rate of drug diffusion into and out of the cell, and the intrinsic vulnerability of drug targets with regard to the corresponding antimicrobial agent. Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), remains a significant source of global morbidity and mortality, further exacerbated by its ability to readily evolve drug resistance. It is well accepted that drug resistance in M. tuberculosis is driven by the acquisition of chromosomal mutations in genes encoding drug targets/promoter regions; however, a comprehensive description of the molecular mechanisms that fuel drug resistance in the clinical setting is currently lacking. In this context, there is a growing body of evidence suggesting that active extrusion of drugs from the cell is critical for drug tolerance. M. tuberculosis encodes representatives of a diverse range of multidrug transporters, many of which are dependent on the proton motive force (PMF) or the availability of ATP. This suggests that energy metabolism and ATP production through the PMF, which is established by the electron transport chain (ETC), are critical in determining the drug susceptibility of M. tuberculosis. In this review, we detail advances in the study of the mycobacterial ETC and highlight drugs that target various components of the ETC. We provide an overview of some of the efflux pumps present in M. tuberculosis and their association, if any, with drug transport and concomitant effects on drug resistance. The implications of inhibiting drug extrusion, through the use of efflux pump inhibitors, are also discussed.

Identification and antibiotic susceptibility of coagulase negative staphylococci isolated from dairy cows with subclinical mastitis

Aim: This study was aimed to identify of coagulase negative staphylococci (CNS) isolated from bovine milk samples with subclinical mastitis and to determine susceptibility of microorganisms to antibiotics. Materials and Methods: Totally, 286 CNS isolates from milk samples were identified according to colony morphology, haemolysis and biochemical properties. Results: Out of isolates, 40 (14.38%) were identified as S. simulans, 31 (11.15%) S. epidermidis, 54 (19.42%) S. chromogenes, 31 (11.15%) S. xylosus, 22 (7.91%) S. caprae, 19 (6.83%) S. warneri, 18 (6.47%) S. haemolyticus, 13 (4.67%) S. cheiferi subsp. coagulans, 10 (3.59%) S. cohneii subsp. urealyticus, 10 (3.59%) S. saprophyticus, 6 (2.15%) S. gallinarum, 7 (2.51%) S. hominis, 4 (1.43%) S. hyicus, 2 (0.71%) S. cheiferi subsp. cheiferi, 9 (3.23%) S. lentus and 2 (0.71%) S. sciuri. The susceptibilities of CNS were determined to be variable to different antimicrobial agents. Conclusions: This study was shown that identification of CNS isolated from dairy cows with subclinical mastitis should be strictly performed.

Antimicrobial Action of Minocycline Microspheres Versus 810‐nm Diode Laser on Human Dental Plaque Microcosm Biofilms

The purpose of this study is to investigate the antimicrobial effects of minocycline hydrochloride microspheres versus infrared light at 810 nm from a diode laser on multispecies oral biofilms in vitro. These biofilms were grown from dental plaque inoculum (oral microcosms) and were obtained from six systemically healthy individuals with generalized chronic periodontitis. Multispecies biofilms were derived using supra- and subgingival plaque samples from mesio-buccal aspects of premolars and molars exhibiting probing depths in the 4- to 5-mm range and 1- to 2-mm attachment loss. Biofilms were developed anaerobically on blood agar surfaces in 96-well plates using a growth medium of prereduced, anaerobically sterilized brain-heart infusion with 2% horse serum. Minocycline HCl 1 mg microspheres were applied on biofilms on days 2 and 5 of their development. Biofilms were also exposed on days 2 and 5 of their growth to 810-nm light for 30 seconds using a power of 0.8 W in a continuous-wave mode. The susceptibility of microorganisms to minocycline or infrared light was evaluated by a colony-forming assay and DNA probe analysis at different time points. At all time points of survival assessment, minocycline was more effective (>2 log10 colony-forming unit reduction) than light treatment (P <0.002). Microbial analysis did not reveal susceptibility of certain dental plaque pathogens to light, and it was not possible after treatment with minocycline due to lack of bacterial growth. The cumulative action of minocycline microspheres on multispecies oral biofilms in vitro led to enhanced killing of microorganisms, whereas a single exposure of light at 810 nm exhibited minimal and non-selective antimicrobial effects.

Antibiotic expected effectiveness and cost under real life microbiology: evaluation of ertapenem and ceftriaxone in the treatment of community-acquired pneumonia for elderly patients in Spain

BackgroundClinical efficacy of antibiotics may be affected by changes in the susceptibility of microorganisms to antimicrobial agents. The purpose of this study is to assess how these changes could affect the initial efficacy of ertapenem and ceftriaxone in the treatment of community-acquired pneumonia (CAP) in elderly patients and the potential consequences this may have in health care costs.MethodsInitial efficacy in elderly was obtained from a combined analysis of two multicenter, randomized studies. An alternative scenario was carried out using initial efficacy data according to the pneumonia severity index (PSI). Country-specific pathogens distribution was obtained from a national epidemiological study, and microbiological susceptibilities to first- and second-line therapies were obtained from Spanish or European surveillance studies. A decision analytic model was used to compare ertapenem versus ceftriaxone for CAP inpatient treatment. Inputs of the model were the expected effectiveness previously estimated and resource use considering a Spanish national health system perspective. Outcomes include difference in proportion of successfully treated patients and difference in total costs between ertapenem and ceftriaxone. The model performed one-way and probabilistic sensitivity analyses.ResultsFirst-line treatment of CAP with ertapenem led to a higher proportion of successfully treated patients compared with ceftriaxone in Spain. One-way sensitivity analysis showed that length of stay was the key parameter of the model. Probabilistic sensitivity analysis showed that ertapenem can be a cost-saving strategy compared with ceftriaxone, with a 59% probability of being dominant (lower costs with additional health benefits) for both, elderly patients (>65 years) and patients with PSI >3.ConclusionThe incorporation of the current antimicrobial susceptibility into the initial clinical efficacy has a significant impact in outcomes and costs in CAP treatment. The treatment with ertapenem compared with ceftriaxone resulted in better clinical outcomes and lower treatment costs for two segments of the Spanish population: elderly patients and patients with severe pneumonia (PSI >3).

Antimicrobial Resistance in the 21st Century: A Multifaceted Challenge

Antimicrobial resistance, the ability of (pathogenic) bacteria to withstand the action of antibiotic drugs, has recently been rated of having an impact on humans similar to that of global climate change. Indeed, during the last years medicine has faced the development of highly resistant bacterial strains, which were, as a consequence of worldwide travel activity, dispersed all over the globe. This is even more astonishing if taking into account that antibiotics were introduced into human medicine not even hundred years ago. Resistance covers different principle aspects, natural resistance, acquired resistance and clinical resistance. In the modern microbiology laboratory, antimicrobial resistance is determined by measuring the susceptibility of micro-organisms in vitro in the presence of antimicrobials. However, since the efficacy of an antibiotic depends on its pharmacokinetic and pharmacodynamics properties, breakpoints are provided to translate minimal inhibitory concentration to categorical efficacy (i.e. susceptible or resistant). Resistance in one microorganism against one particular drug may drive treatment decisions of clinicians, thereby fostering selection pressure to resistance development against another antibiotic. Thereby, bacteria may acquire more and more resistance traits, ending up with multi-resistance. To this end, antimicrobial resistance becomes a public health concern, not only in terms of limited treatment options but also due to its economic burden. The current paper provides a summary of the main topics associated with antimicrobial resistance as an introduction to this special issue.

Laboratory to Clinical Investigation of Carbapenem Resistant Acinetobacter baumannii Outbreak in a General Hospital

Background:The number of reported cases, infected with carbepenem resistant Acinetobacter baumannii (CRAb) and multi-drug resistant (MDR) Acinetobacter species had gradually increased in most PLA general hospital wards from April to June in 2007.Objectives:We have described the investigation of an outbreak of CRAb and MDR Acinetobacter in PLA general hospital, Beijing. The prospective and retrospective findings were identified and analyzed to study the infection causes.Materials and Methods:A. baumannii samples were collected from the patients and environment in each hospital unit. The onset times were recorded according to their case information. All samples were characterized by genotype and compared using pulsed-field gel electrophoresis (PFGE). The microorganism susceptibility was tested using the in vitro minimal inhibitory concentration (MIC) breakpoints method.Results:A total of 69 A. baumannii strains were successfully isolated from 53 patients. About 89.1% of them were resistant to ampicillin and 89.2% to cefotaxime and 75.4% to all standard antibiotics. PFGE analysis revealed that nine of the isolates had unique clones and the epidemic clone types were A, B and C.Conclusions:The A. baumannii outbreak, was caused by MDR A. baumannii. The strains had widely spread among 12 departments especially in surgical intensive care unit (SICU), emergency intensive care unit (EICU) and the department of respiratory disease. The outbreak was more likely caused by the A. baumannii infected or carrier patients and EICU was its origin.

The In Vitro Susceptibility of Biofilm Forming Medical Device Related Pathogens to Conventional Antibiotics

Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) and kill kinetics were established for vancomycin, rifampicin, trimethoprim, gentamicin, and ciprofloxacin against the biofilm forming bacteria Staphylococcus epidermidis (ATCC 35984), Staphylococcus aureus (ATCC 29213), Methicillin Resistant Staphylococcus aureus (MRSA) (ATCC 43300), Pseudomonas aeruginosa (PAO1), and Escherichia coli (NCTC 8196). MICs and MBCs were determined via broth microdilution in 96‐well plates. MBECs were studied using the Calgary Biofilm Device. Values obtained were used to investigate the kill kinetics of conventional antimicrobials against a range of planktonic and biofilm microorganisms over a period of 24 hours. Planktonic kill kinetics were determined at 4xMIC and biofilm kill kinetics at relative MBECs. Susceptibility of microorganisms varied depending on antibiotic selected and phenotypic form of bacteria. Gram‐positive planktonic isolates were extremely susceptible to vancomycin (highest MBC: 7.81 mg L−1: methicillin sensitive and resistant S. aureus) but no MBEC value was obtained against all biofilm pathogens tested (up to 1000 mg L−1). Both gentamicin and ciprofloxacin displayed the broadest spectrum of activity with MIC and MBCs in the mg L−1 range against all planktonic isolates tested and MBEC values obtained against all but S. epidermidis (ATCC 35984) and MRSA (ATCC 43300).

Aetiological profile and antibiotic susceptibility pattern in patients with urinary tract infection in tripura.

Aetiological profile and antibiotic susceptibility pattern in patients with urinary tract infection in tripura.

Urinary infection in patients of public health care of Campo Mourão-PR, Brazil: bacterial prevalence and sensitivity profile

Introduction: Cases of bacterial resistance in urinary tract infections (UTIs) have increased significantly, mainly due to indiscriminate use of antimicrobials. Objective: Objective: To evaluate the prevalence and antimicrobial susceptibility of microorganisms isolated in urine cultures of patients of Consórcio Intermunicipal de Saúde da Comunidade dos Municípios da Região de Campo Mourão (CISCOMCAM) clinical laboratory. Method: We performed a retrospective study of data from urine culture and sensitivity done between January 2012 and December 2013. Results: The most prevalent bacteria were Escherichia coli; women were the most affected gender and people 16-45 years, the most affected age group. The sensitivity profile showed that the antimicrobial combination trimethoprim/ sulfamethoxazole was not associated with the highest rate of bacterial resistance (59.7%) and the combination of amoxicillin/clavulanic acid showed the lowest resistance rate (15.3%). For most antimicrobials, including ciprofloxacin and norfloxacin, the rates of bacterial resistance have increased from 2012 to 2013 with statistical significance (p < 0.05) in some cases. Discussion: The prevalence of Gram-negative bacilli in urinary infections is due to the fact that intestinal flora is rich in enterobacteria, and women are most affected by anatomical factors. The development of bacterial resistance to antimicrobials probably arises from their indiscriminate use. Conclusion: The rate of microbial resistance has risen, showing the need for a more effective control of antimicrobial use.

Characterization and antimicrobial activity of gold and silver nanoparticles synthesized using saponin isolated from Trianthema decandra L.

Synthetic methods based on naturally occurring biomaterials provide an alternative, environmental-friendly means of obtaining nanoparticles. We describe, one step green synthesis of gold (AuNPs) and silver nanoparticles (AgNPs) using a benign solvent, i.e., water and a surfactant isolated from Trianthema decandra, i.e., saponin without any special reducing or capping agents. On treatment of aqueous solutions containing chloroauric acid or silver nitrate with a solution of saponin isolated from T. decandra, stable gold or silver nanoparticles were rapidly formed. The reduction of gold and silver ions during the reaction was analyzed by ultraviolet–visible spectroscopy. Field emission-scanning electron microscopy showed formation of gold nanoparticles in various shapes, including spherical, cubical and hexagonal, while silver nanoparticles were spherical. The size of the gold nanoparticles was 37.7–79.9nm and that of the silver nanoparticles was 17.9–59.6nm. Energy dispersive X-ray and Fourier transform infrared spectroscopy confirmed the presence of metallic gold and metallic silver in the respective nanoparticles. The antimicrobial activity of the synthesized nanoparticles was analyzed using the Kirby–Bauer method, indicated varied susceptibility of microorganisms to the gold and silver nanoparticles.

Etiology of Diabetic Foot Infection in Patients with Poorly Controlled Diabetes

SummaryThe aim of the study was to define the spectrum and susceptibility of microorganisms, isolated from diabetic foot ulcers in patients with poorly controlled diabetes, treated at the clinic of surgery, and compare microbial findings of specimens collected superficially and from deep tissues. The study included 19 patients with type 1 and 2 diabetes with clinical signs of infection. All patients were with poorly controlled diabetes and staged from 3rd to 5th grade according to the Wagner diabetic foot scale. Swab samples from non-debrided wounds and biopsy samples from deep tissues were collected from each patient. Specimens were inoculated on media for isolation of aerobic and anaerobic bacteria. Identification and susceptibility testing of the isolated oiganisms were performed by conventional methods, and VITEK 2 and mini API Systems (bioMerieux, France). A total of 88 bacterial isolates were cultured, comprising 56 clinical strains. Gram positive bacteria were the most common isolated organisms (53.57%), followed by Gram negative bacteria (26.78%) and anaerobic bacteria (19.64%). Staphylococcus aureus was the most common organism detected (10 strains), followed by Enterococcus spp. (7 strains), Escherichia coli (7 strains), Bacteroides spp. (6 strains) and various other organisms of low incidence. Polymicrobial infection was detected in 17 (89.47%) of the patients. In most of the cases infections were caused by 3 bacterial species. Mixed aerobic/anaerobic infections were detected in 9 (47.3%) patients. In 15 (78.94%) patients, there was a coincidence of bacterial findings from superficial and deep tissue samples. The strains isolated were susceptible to commonly used antimicrobials for treatment of diabetic foot infection. The predominant part of the diabetic foot infections were polymicrobial, caused by association between two or three microbial species. In half of the cases the infection was mixed. There was a good correlation between microbial findings from superficial swabs and deep tissue specimens when they were delivered to the microbiology laboratory immediately after collection.

Mechanism of action and initial evaluation of a membrane active all- D -enantiomer antimicrobial peptidomimetic

Development of therapy against infections caused by antibiotic-resistant pathogens is a major unmet need in contemporary medicine. In previous work, our group chemically modified an antimicrobial peptidomimetic motif for targeted applications against cancer and obesity. Here, we show that the modified motif per se is resistant to proteolytic degradation and is a candidate antiinfective agent. We also show that the susceptibility of microorganisms to the drug is independent of bacterial growth phase. Moreover, this peptidomimetic selectively interferes with the integrity and function of the microbial surface lipid bilayer, data indicative that bacterial death results from membrane disruption followed by dissipation of membrane potential. Finally, we demonstrate two potential translational applications: use against biofilms and synergy with antibiotics in use. In summary, we introduce the mechanism of action and the initial evaluation of a prototype drug and a platform for the development of D-enantiomer antimicrobial peptidomimetics that target bacterial membranes of certain gram-negative problem pathogens with promising translational applications.

Antimicrobial and Antioxidant Evaluation of Flacourtia Ramontchi L. Herit

In vitro antimicrobial activity of extracts of F. ramontchi was evaluated against gram-positive bacteria, gram-negative bacteria and against fungi using cup-plate agar diffusion and disc diffusion methods. Susceptibility of microorganisms to the extracts was compared with one another and with selected antibiotics. Minimum inhibitory concentration was determined by agar dilution technique. Antioxidant activity of extracts was evaluated by 1, 1-diphenyl-2-picryl-hydrazyl radical- scavenging assay, nitric oxide radical-scavenging assay, and hydrogen peroxide–scavenging assay. Lipid peroxidation, reduced glutathione content, superoxide dismutase, and catalase activities were assessed by in vivo antioxidant methods. Total phenolic content and total flavonoid content were evaluated. All extracts showed antimicrobial and antioxidant activity compared to control.

Application of CFD Simulation to Predicting Upper‐Room UVGI Effectiveness

This study outlines the potential for Computational Fluid Dynamics (CFD) simulation to be used to predict upper-room ultraviolet germicidal irradiation (UVGI) effectiveness to aid system design and the development of future guidance. A numerical study of two wall-mounted UVGI lamps in a mechanically ventilated test chamber is used to assess the influence of modeling parameters on prediction of dose distribution and microorganism inactivation. Irradiance fields for both UVGI fixtures are obtained via radiometry and implemented in the model. A series of sensitivity studies consider the importance of UVGI field accuracy and computational grid and turbulence model selection. Results show that 2D irradiance fields are sufficient for calculating dose and in-activation, whereas a 1D field is inadequate for modeling purposes. Further parametric studies consider the effects of ventilation parameters, UVGI lamp configuration and microorganism susceptibility. These demonstrate the feasibility of modeling the interaction of the airflow and UV field in a room to quantify the dose distribution. Microorganism in-activation can also be accomplished by employing passive scalars and species transport models, however, further validation data are necessary before this can be used to make reliable quantitative predictions.

Selection of prophylactic antibiotics according to the microorganisms isolated from surgical site infections (SSIs) in a previous series of surgeries reduces SSI incidence after pancreaticoduodenectomy

The incidence of surgical site infections (SSIs) is high after pancreaticoduodenectomy (PD). We divided 116 consecutive patients who underwent PD into an early group (n = 58) and a later group (n = 58) according to time of surgery. In both groups, endoscopic retrograde biliary drainage was mainly employed for the patients with obstructive jaundice. In the later group, prophylactic antibiotics were selected according to the susceptibility of microorganisms isolated from SSIs in the early group. The incidence of SSIs was compared between the groups. The background characteristics (including methods of preoperative biliary drainage and microorganisms in the bile obtained before or during operation) of the patients were not significantly different between the groups, except for the serum albumin level, which was lower in the later group than in the early group (P = 0.0026). The incidence of SSIs was significantly lower in the later group (24.1 %) than in the early group (46.6 %) (P = 0.0116). Belonging to the later group was one independent negative risk factor for SSI. Selection of prophylactic antibiotics on the basis of microorganisms isolated from SSIs in the early group contributed to the reduced incidence of SSIs in the later group after PD.

Antibiotics surveillance: a survey on the susceptibility of microorganisms to antibiotics in respiratory tract infections

BackgroundSusceptibility of microorganisms to antibiotics is clearly decreasing in many Asian countries and is of particular concern in Streptococcus pneumoniae. The genetic relationship between penicillin-resistant S pneumoniae strains from across...

Identification and Antimicrobial Susceptibility of Microorganisms Isolated from the Preputium of Healthy Dogs

Identification and Antimicrobial Susceptibility of Microorganisms Isolated from the Preputium of Healthy Dogs

Gold and silver nanoparticles from Trianthema decandra: synthesis, characterization, and antimicrobial properties

BackgroundThere is an increasing commercial demand for nanoparticles due to their wide applicability in various markets, including medicine, catalysis, electronics, chemistry, and energy. In this report, a simple and ecofriendly chemical reaction for the synthesis of gold and silver nanoparticles from Trianthema decandra (Aizoaceae) has been developed.Methods and resultsOn treatment of aqueous solutions containing chloroauric acid or silver nitrate with root extract of T. decandra, stable gold or silver nanoparticles were rapidly formed. The kinetics of reduction of gold and silver ions during the reaction was analyzed by ultraviolet-visible spectroscopy. Field emission-scanning electron microscopy showed formation of gold nanoparticles in various shapes, including spherical, cubical, triangular, and hexagonal, while silver nanoparticles were spherical. The size of the gold nanoparticles was 33–65 nm and that of the silver nanoparticles was 36–74 nm. Energy dispersive x-ray and Fourier transform infrared spectroscopy confirmed the presence of metallic gold and metallic silver in the respective nanoparticles. The antimicrobial properties of the synthesized nanoparticles were analyzed using the Kirby-Bauer method. The results show varied susceptibility of microorganisms to the gold and silver nanoparticles.ConclusionIt is believed that phytochemicals present in T. decandra extract reduce the silver and gold ions into metallic nanoparticles. This strategy reduces the cost of production and the environmental impact. The silver and gold nanoparticles formed showed strong activity against all microorganisms tested.

Antibiotic susceptibility of methicillin-resistant and methicillin-susceptible coagulase-negative staphylococci isolated from bovine mastitis

The aim of the present study was to evaluate the antibiotic susceptibility of methicillin-susceptible (MS) and methicillin-resistant (MR) coagulase-negative Staphylococcus (CNS) strains isolated from milk of cows with mastitis. The study was conducted on 100 CNS strains (20 MRCNS and 80 MSCNS) isolated from milk samples of 86 cows from the Lublin (Poland) region farms. Antibiotic susceptibility of microorganisms was evaluated using the disc-diffusion method on the Mueller-Hinton agar according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS). The highest efficacy against MSCNS was demonstrated for cephalosporin antibiotics, i.e. cefacetril (91.3%), ceftiofur (67.5%), cefoperazone (66.3%) and cephalexin (60.0% of susceptible MSCNS strains). Moreover, a high percentage of vancomycin-susceptible strains was demonstrated (83.8%). The activity of combination of amoxicillin with clavulanic acid and gentamicin was found weaker (63.8% and 61.3% of susceptible strains, respectively). About 50.0% of MSCNS were susceptible to erythromycin, enrofloxacine and amoxicillin. A large proportion of CNS was resistant to neomycin, penicillin, tetracycline, streptomycin, lincomycin and ampicillin (28.8%, 30.0%, 31.3%, 31.3%, 33.8% and 33.8% of susceptible strains, respectively). The highest percentage of MRCNS was susceptible to vancomycin (75.0%), erythromycin (65.0%) and streptomycin (50.0%). Their susceptibility to enrofloxacine (35.0%) as well as gentamicin and tetracycline (30.0%) was markedly lower. The lowest activity was found for lincomycin and neomycin (20.0% of susceptible MRCNS strains, each).