Narrow Results

The response of bacterial populations to antibiotic treatment is often a function of a diverse range of interacting factors. In order to develop strategies to minimize the spread of antibiotic resistance in pathogenic bacteria, a sound theoretical understanding of the systems of interactions taking place within a colony must be developed. The agent-based approach to modeling bacterial populations is a useful tool for relating data obtained at the molecular and cellular level with the overall population dynamics. Here we demonstrate an agent-based model, called Micro-Gen, which has been developed to simulate the growth and development of bacterial colonies in culture. The model also incorporates biochemical rules and parameters describing the kinetic interactions of bacterial cells with antibiotic molecules.

Simulations were carried out to replicate the development of methicillin-resistant S. aureus (MRSA) colonies growing in the presence of antibiotics. The model was explored to see how the properties of the system emerge from the interactions of the individual bacterial agents in order to achieve a better mechanistic understanding of the population dynamics taking place. Micro-Gen provides a good theoretical framework for investigating the effects of local environmental conditions and cellular properties on the response of bacterial populations to antibiotic exposure in the context of a simulated environment.

Infection caused by antibiotic-resistant pathogens is one of global public health problems. Many factors contribute to the emergence and spread of these pathogens. A model which describes the transmission dynamics of susceptible and resistant bacteria in a pregnant woman and the fetus is presented. Detailed qualitative analysis about positivity, boundedness, global stability and uniform persistence of the model is carried out. Numerical simulation and sensitivity analysis show that antibiotic input has potential impact for neonatal drug resistance. Our results show that the resistant bacteria in baby mainly come from antibiotics which are wrongly-used during gestational period, or foods containing antibiotic residues.

Purpose: To determine the rate of antibiotic elution from tobramycin-impregnated ProOsteon (Interpore) and Collagraft (Zimmer). Methods: Five samples of Collagraft and ProOsteon were impregnated with a solution containing 1.2 g of tobramycin and 10 ml of sterile water. The samples were then allowed to dry overnight. These samples were stored at 37°C in separate test tubes containing phosphate buffered saline (PBS). The solution in each test tube was removed with a pipette at hours 3, 6, 9 and 12 and days 1, 2, 3, 5, 7, 9, 11 and 13. The PBS was then replaced. The pipetted solution was sent for laboratory quantification and also used in a bioassay to determine antibiotic level. To serve as a control, two additional samples of each bone graft that were not impregnated with antibiotic were placed in separate test tubes and subjected to the same protocol. Results: The antibiotic elution rate for both ProOsteon and Collagraft was high at 3 hours [5362 and 4875 μg/ml on day 3 (3.1 μg/ml) for the Collagraft and day 7 (3.7 μg/ml) for the ProOsteon]. Effective intravenous tobramycin level is considered to be 4–6 μg/ml. Conclusion: Bone graft substitute can be used as a delivery vehicle for tobramycin. In addition, antibiotic-impregnated synthetic bone graft may potentially fill a dead space or cavitary defect without the need for large autologous grafts and does not require later removal.

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Antibiotic-impregnated poly(methyl methacrylate) (PMMA) bone cement has been successfully used to treat infected joint arthroplasties and surgeons have advocated the use of antibiotic-treated bone cement to prevent possible infections in joint replacement surgeries. However, there is a concern that this addition may adversely affect the mechanical properties of the bone cement. In most cases, the addition of antibiotics to bone cement has been reported to lower its mechanical strength. The uniaxial, biaxial and three/four point bending tests of antibiotic-impregnated bone cement have been extensively performed and well documented. However, only a few documents have focused on the impact strength of bone cement. The present study reports the impact tests of control and antibiotic loaded bone cements at different temperatures and aging conditions. According to the results, the addition of gentamicin or vancomycin significantly reduced the samples' impact strength. Moreover, the samples aged in saline at 23${}^{\circ }$C were more resistant than the samples aged in air at 23${}^{\circ }$C. Furthermore, raising the storage temperature from 23${}^{\circ }$C to 37${}^{\circ }$C significantly lowered the bone cement's impact strength in both control and antibiotic loaded samples.

Canine pyometra is a common reproductive disease in bitches. This study evaluated the causative bacteria in antibiotic sensitivity test. Fifty five bitches with pyometra were included in this study. Escherichia coli was the most isolated microorganism (63.6%), followed by Streptococcus spp. (10.9%). Sixty two pathogen isolates showed highest sensitivity to imipenem (95.2%), followed by gentamicin (85.5%), amikacin (80.6%), ceftazidime (72.6%), nitrofurantoin (72.6%), and norfloxacin (72.6%). The microorganisms were most resistant to lincomycin (96.8%), followed by penicillin (85.5%), trimethoprim/sulfamethoxazole (58.1%), amoxicillin (54.8%), ampicillin (53.2%), and cefadroxil (50%). The sensitivity of a single empirical antibiotic treatment applied without sensitivity test was 51% (25/49). Sensitivity increased to 84.6% (11/13) when two antibiotics are used simultaneously. No significant differences in the proportions of clinical signs and abnormal hematologic results were observed between bitches with open- and closed-type pyometra. All bitches with pyometra recovered after ovariohysterectomy, antibiotic administration, and supportive therapy. The results of this study provide reliable information to choose an effective antibiotic before surgical intervention, especially for critical patients who cannot wait for the sensitivity test. The outcomes of the bitches with pyometra were excellent with early diagnosis and appropriate treatment.

The adequate method of antibiotic choice is reported using the laser fluorescence analysis of blood plasma with the laboratory diagnostic device "Spectrolux-MB". The method is based on the ability of micro-organisms and products of their vital functions (metabolism) to fluoresce under laser radiation. The method of fluorescence analysis has great prospects in urgent surgery and other medicine brunches due to its high information content, low cost (compared to other methods of express-diagnostics) and high speed of information acquisition.

Strain PT708 was isolated from cave soil at Pha Tup Cave Forest Park, Nan Province, Thailand. Phylogenetic analysis indicated that it belongs to the genus Nonomuraea, with a relatively high similarity value (98.28%) to the 16S rRNA gene sequence to Nonomuraea roseola AJ278221 and Nonomuraea dietziae AJ278220. However, its unique morphology, forming a single spore at the end of branched mycelium, is different with those species of the genus Nonomuraea. Consequently, we propose that the strain should be assigned to a new species in this genus. Strain PT708 showed ability to produce antimicrobial compounds against Bacillus cereus, methicillin-resistant Staphylococcus aureus (MRSA) and Paenibacillus larvae when it was grown in AMHU-5 medium. MRSA and B. cereus are the most susceptible strains, with equal MIC values of 80 μg/mL followed by P. larvae with MIC value of 175 μg/mL. Moreover, a crude extract from this strain showed anticancer activities against human small cell lung cancer (NCI-H187) and human oral cavity cancer (KB) with IC₅₀ values of 3.48 and 16.11 μg/mL, respectively, but no inhibition was observed for human breast cancer (MCF7) with concentration up to 50 μg/mL.

The aim of this study was to evaluate the susceptibility to antibiotics and quaternary ammonium disinfectants of Acinetobacter baumannii strains isolated from patients with nosocomial infections and the environment of the ICU and Neonatal Service (NS) at the Caracas University Hospital. Resistance to 15 antibiotics was determined. To evaluate the disinfectant resistance phenotypes tests recommended by the AOAC were used. ERIC-PCR and REP-PCR were used for genotyping. We analyzed 74 A. baumannii, 14 and 1 from ICU and NS patients, respectively; and 42 and 17 from its corresponding environments. 44.6% of the isolates showed resistance to at least 7 antibiotics. 54% of isolates tested exhibited the resistance phenotypes to the quaternary ammonium hospital disinfectant evaluated. 73% of the isolates from patients were closely related clones, 28.8% of the environmental isolates were grouped in 7 indistinguishable clones groups. The multiple antibiotic and disinfectant resistance profiles and the presence of related bacterial clones demonstrate the need for antibiotic usage surveillance and alternative cleaning methods in this hospital.