Sobrevivência e desenvolvimento de Pseudomonas aeruginosa em água mineral experimentalmente contaminada / Survival and growth of Pseudomonas aeruginosa in experimentally contaminated mineral water

Pseudomonas aeruginosa, agente patogênico oportunista, é frequentemente encontrado em águas minerais e pode causar infecções em indivíduos imunocomprometidos. Neste estudo foi avaliada a sobrevivência e/ou a multiplicação de P. aeruginosa em amostras de água mineral em embalagens plásticas de 1,5 L e 20 L, experimentalmente contaminadas, armazenadas a 35 ± 1ºC, 4 ± 2°C e em temperatura ambiente (20-25ºC), durante o período de validade do produto. Nas amostras de água mineral em garrafa plástica de 1,5 L, armazenadas a 35 ± 1ºC e 4 ± 2ºC, a população de P. aeruginosa manteve-se viável durante 370 e 100 dias, respectivamente. O maior aumento da população bacteriana ocorreu nas amostras de água mineral em galão de 20 L, armazenadas entre 20 a 25ºC, que passou de 3,8 para 6,6 log10 UFC/mL em um período de sete dias. Portanto, os galões de 20 L merecem atenção especial, pois além de serem retornáveis, normalmente são armazenados à temperatura ambiente. Os resultados reforçam a necessidade das empresas de águas minerais implantarem e implementarem as Boas Práticas de Fabricação (BPF) e o sistema Análise de Perigo e Pontos Críticos de Controle (APPCC) para eliminar ou minimizar os riscos do consumo deste produto.

Pseudomonas aeruginosa, an opportunistic pathogen, is often found in bottled waters and capable of infecting the immunocompromised patients. The present study aimed at evaluating the survival and/ or the growth of P. aeruginosa strain in 1,5 L and 20 L bottled mineral water samples experimentally contaminated, stored at 35 ± 1°C, 4 ± 2°C, and at room temperature (from 20 to 25°C) during the product shelf-life period. In the mineral water samples contained in 1.5 L bottles, stored at 35 ± 1ºC and 4 ± 2ºC, P. aeruginosa remained viable for 370 and 100 days, respectively. The major increase in the bacterial population occurred in mineral water samples in 20 L bottles stored at 20 to 25ºC, being from 3.8 to 6.6 log10 CFU/mL, in a period of seven days. Therefore, the 20 L bottles deserve a special attention because, in addition of being returnable, they are usually stored at room temperature. The results reinforce the need of the mineral water companies in implementing the Good Manufacturing Practice (GMP) and the HACCP (Hazard Analysis Critical Control Point) to eliminate and to minimize the risks of consuming the contaminated product.

Regulação da expressão de pioverdina dependente de contato em pseudomonas aeruginosa / Regulation of surface-dependent pyoverdine expression in Pseudomonas aeruginosa

A gama-proteobactéria Pseudomonas aeruginosa é um patógeno oportunista humano frequentemente associado a pacientes com queimadura grave e aos portadores de fibrose cística. O estabelecimento de infecção depende de uma série de fatores que contribuem para a virulência deste patógeno, dentre eles a produção de sideróforos e outros sistemas de captação de ferro. Pioverdina é o principal sideróforo sintetizado por bactérias do gênero Pseudomonas e linhagens deficientes na sua produção são incapazes de estabelecer infecção em modelos animais. A regulação da biossíntese deste sideróforo envolve a agregação entre as células, indicando a dependência de contato para completa indução da sua produção. O contato com uma superfície altera o comportamento das células e diversos fenótipos são dependentes deste sinal mecânico. PrlC é uma oligopeptidase A putativamente envolvida na degradação de peptídeo-sinais e PA14_00800, uma pequena proteína com domínio de função desconhecida, codificada por um gene imediatamente à jusante de prlC. Existem poucos trabalhos na literatura sobre PrlC e seus homólogos e nenhuma informação sobre PA14_00800. Este trabalho teve como objetivo elucidar o envolvimento de PrlC e PA14_00800 na regulação da produção de pioverdina por células em contato com uma superfície. Para estabelecer uma correlação na expressão destes genes, um estudo da organização gênica foi realizado por RT-PCR, confirmando que eles fazem parte do mesmo operon e, portanto, que a expressão destes genes é regulada pelos mesmos fatores. Ensaios classicamente modulados pelo segundo mensageiro c-di-GMP, como formação de biofilme e motilidade, não apresentaram variações nas linhagens mutantes ΔprlC, ΔPA14_00800 ou Δoperon, indicando que a deleção destes genes não altera significativamente os níveis de c-di-GMP nas células. A motilidade do tipo swarming é, no entanto, severamente afetada na linhagem ΔPA14_00800 quando o meio de cultura não contém cloreto de cálcio e glicose, indicando um defeito na sinalização celular ou requerimento energértico desta linhagem nestas condições. PA14_00800 regula a fluorescência de P. aeruginosa em meio sólido e semissólido, mas não em meio líquido. Esta fluorescência depende tanto de pioverdina quanto de PQS, umamolécula de comunicação celular fluorescente, e a possibilidade de outros fatores estarem envolvidos neste fenótipo ainda está sob investigação. Análise do transcritoma por RNASeq com a linhagem ΔPA14_00800 comparada à linhagem parental foi realizada a partir de colônias destas linhagens crescidas em M9 modificado. Genes envolvidos no sistema de secreção do tipo III e do tipo VI e na biossíntese de PQS apareceram dentre os genes diferencialmente expressos, bem como genes para o catabolismo de glicose. Este trabalho foi o primeiro a investigar o papel de PA14_00800 na fisiologia de P. aeruginosa, e os conhecimentos adquiridos aqui podem ser transpostos, com cautela, para compreensão da função dos homólogos de PA14_00800 em outras bactérias

The gamma-proteobacterium Pseudomonas aeruginosa is a human opportunistic pathogen frequently associated with patients with severe burns and those with cystic fibrosis. The establishment of infection depends on several factors that contribute to the virulence of this pathogen, among them siderophore production and other iron uptake systems. Pyoverdine is the main siderophore synthesized by the bacteria of the genus Pseudômonas and pyoverdinedeficient strains are unable to establish infection in animal models. The regulation of biosynthesis of this siderophore involves cell aggregation, indicating contact dependency for complete induction of pyoverdine production. Surface contact alters cell behavior and several phenotypes are dependent on this mechanical cue. PrlC is an oligopeptidase A putatively involved in peptide-signals degradation and PA14_00800, a small protein with a domain of unknown function, encoded by a gene immediately downstream of prlC. There are few papers in the literature on PrlC and its homologues and no information on PA14_00800. This work aimed to elucidate the role of PrlC and PA14_00800 in surface-dependent regulation of pyoverdine production. To establish a correlation in the expression of these genes, a study of the gene organization was performed by RT-PCR, confirming that they are part of an operon and therefore the expression of these genes is regulated by the same factors. Traits classically modulated by the second messenger c-di-GMP, such as biofilm formation and motility, did not show variations in the ΔprlC, ΔPA14_00800 or Δoperon, indicating that the deletion of these genes does not significantly alter the levels of c-di-GMP within the cells. Swarming motility is, however, severely affected in the strain ΔPA14_00800 when the culture medium does not contain calcium chloride and glucose, indicating a cell signaling defect or energetic requirement under these conditions. PA14_00800 regulates surface-dependent fluorescence of P. aeruginosa, in solid and semi-solid medium. This fluorescence depends on both pyoverdine and PQS, a fluorescent cell-to-cell communication molecule, and the investigation of other putative factors involved in this phenotype is still under study. Transcriptomic analysis by RNASeq with the strain ΔPA14_00800 compared to PA14 was performed from colonies ofthese strains grown in modified M9 1% agar. Genes involved in the type III and type VI secretion systems, in PQS biosynthesis and glucose catabolism were differentially expressed. This work was the first to investigate the role of PA14_00800 in the physiology of P. aeruginosa, and the knowledge obtained here can be cautiously transposed to understanding the role of PA14_00800 homologues in other bactéria

Biofilm production by clinical isolates of Pseudomonas aeruginosa and structural changes in LasR protein of isolates non biofilm-producing

ABSTRACT Introduction: Biofilm production is an important mechanism for the survival of Pseudomonas aeruginosa and its relationship with antimicrobial resistance represents a challenge for patient therapeutics. P. aeruginosa is an opportunistic pathogen frequently associated to nosocomial infections, especially in imunocompromised hosts. Objectives: Analyze the phenotypic biofilm production in P. aeruginosa isolates, describe clonal profiles, and analyze quorum sensing (QS) genes and the occurrence of mutations in the LasR protein of non-biofilm producing isolates. Methods: Isolates were tested for biofilm production by measuring cells adherence to the microtiter plates. Clonal profile analysis was carried out through ERIC-PCR, QS genes were by specific PCR. Results: The results showed that 77.5% of the isolates were considered biofilm producers. The results of genotyping showed 38 distinct genetic profiles. As for the occurrence of the genes, 100% of the isolates presented the lasR, rhlI and rhlR genes, and 97.5%, presented the lasI gene. In this study nine isolates were not biofilm producers. However, all presented the QS genes. Amplicons related to genes were sequenced in three of the nine non-biofilm-producing isolates (all presenting different genetic similarity profile) and aligned to the sequences of those genes in P. aeruginosa strain PAO1 (standard biofilm-producing strain). Alignment analysis showed an insertion of three nucleotides (T, C and G) causing the addition of an amino acid valine in the sequence of the LasR protein, in position 53. Conclusion: The modeling of the resulting LasR protein showed a conformational change in its structure, suggesting that this might be the reason why these isolates are unable to produce biofilm.

Inactivated Pseudomonas aeruginosa inhibits hypoxia-induced pulmonary hypertension by preventing TGF-beta1/Smad signaling

Pseudomonas aeruginosa is one of the common colonizing bacteria of the human body and is an opportunistic pathogen frequently associated with respiratory infections. Inactivated P. aeruginosa (IPA) have a variety of biological effects against inflammation and allergy. Transforming growth factor-β (TGF-β) signaling plays a critical role in the regulation of cell growth, differentiation, and development in a wide range of biological systems. The present study was designed to investigate the effects of IPA on TGF-β/Smad signaling in vivo, using a hypoxia-induced pulmonary hypertension (PH) rat model. Sprague Dawley rats (n=40) were exposed to 10% oxygen for 21 days to induce PH. At the same time, IPA was administered intravenously from day 1 to day 14. Mean pulmonary artery pressure (mPAP) and the right ventricle (RV) to left ventricle plus the interventricular septum (LV+S) mass ratio were used to evaluate the development of PH. Vessel thickness and density were measured using immunohistochemistry. Primary arterial smooth muscle cells (PASMCs) were isolated and the proliferation of PASMCs was assayed by flow cytometry. The production of TGF-β1 in cultured supernatant of PASMCs was assayed by ELISA. The expression levels of α-smooth muscle actin (α-SMA), TGF-β1 and phospho-Smad 2/3 in PASMCs were assayed by western blot. Our data indicated that IPA attenuated PH, RV hypertrophy and pulmonary vascular remodeling in rats, which was probably mediated by restraining the hypoxia-induced overactive TGF-β1/Smad signaling. In conclusion, IPA is a promising protective treatment in PH due to the inhibiting effects on TGF-β1/Smad 2/3 signaling.

Antibacterial, anti-swarming and anti-biofilm formation activities of Chamaemelum nobile against Pseudomonas aeruginosa

Chamomile ( Chamaemelum nobile ) is widely used throughout the world, and has anti-inflammatory, deodorant, bacteriostatic, antimicrobial, carminative, sedative, antiseptic, anti-catarrhal, and spasmolytic properties. Because of the increasing incidence of drug-resistant bacteria, the development of natural antibacterial sources such as medical herbs for the treatment of infectious diseases is necessary. Extracts from different plant parts such as the leaves, flowers, fruit, and bark of Combretum albiflorum, Laurus nobilis , and Sonchus oleraceus were found to possess anti-quorum sensing (QS) activities. In this study, we evaluated the effect of C. nobile against Pseudomonas aeruginosa biofilm formation

Sub-MIC of antibiotics induced biofilm formation of Pseudomonas aeruginosa in the presence of chlorhexidine

Public health is facing a new challenge due to the alarming increase in bacterial resistance to most of the conventional antibacterial agents. It has been found that only minor cell damage is caused when exposed to sub-lethal levels of antimicrobial. Biofilms can play an important role in producing resistance, which is developed to reservoirs of pathogens in the hospital and cannot be easily removed. The aim of this study was to test whether the sub-lethal dose of antibiotics can induce biofilm formation of P. aeruginosa following incubating in the presence and absence of chlorhexidine. Standard antibiotic-micro broth 96-flat well plates were used for determination of MIC and biofilm assay. The adherence degree of biofilm was determined by estimation of OD630 nm values using ELISA reader. The mean 22 isolates of P. aeruginosa growing in culture with presence and absence of chlorhexidine, could exhibited the significant (p < 0.001) proportion of adherence followed incubation in sub minimal inhibitory concentrations (Sub-MIC) of cefotaxim, amoxicillin, and azithromycin in comparison with control (antibiotic-free broth), while the sub-MIC of ciprofloxacin revealed significant inhibition of biofilm. Conclusion: Incubating the isolates of P. aeruginosa to sub-MIC of antibiotics exhibited induction of biofilm in the presence of chlorhexidine.

The efficacy of immediate versus delayed antibiotic administration on bacterial growth and biofilm production of selected strains of uropathogenic Escherichia coli and Pseudomonas aeruginosa

Purpose The treatment of urinary tract infections (UTI) with antibiotics is commonly used, but recurrence and antibiotic resistance have been growing and concerning clinicians. We studied whether the rapid onset of a protective biofilm may be responsible for the lack of effectiveness of antibiotics against selected bacteria. Materials and Methods Two established uropathogenic Escherichia coli strains, UTI89 and CFT073, and two Pseudomonas aeruginosa strains, PA01 and Boston-41501, were studied to establish a reliable biofilm formation process. Bacterial growth (BG) was determined by optical density at 600 nm (OD 600) using a spectrophotometer, while biofilm formation (BF) using crystal violet staining was measured at OD 550. Next, these bacterial strains were treated with clinically relevant antibiotics, ciprofloxacin HCl (200 ng/mL and 2 μg/mL), nitrofurantoin (20 μg/mL and 40 μg/mL) and ampicillin (50 μg/mL) at time points of 0 (T0) or after 6 hours of culture (T6). All measurements, including controls (bacteria -1% DMSO), were done in triplicates and repeated three times for consistency. Results The tested antibiotics effectively inhibited both BG and BF when administered at T0 for UPEC strains, but not when the antibiotic administration started 6 hours later. For Pseudomonas strains, only Ciprofloxacin was able to significantly inhibit bacterial growth at T0 but only at the higher concentration of 2 μg/mL for T6. Conclusion When established UPEC and Pseudomonas bacteria were allowed to culture for 6 hours before initialization of treatment, the therapeutic effect of selected antibiotics was greatly suppressed when compared to immediate treatment, probably as a result of the protective nature of the biofilm. .

Influence of glyphosate in planktonic and biofilm growth of Pseudomonas aeruginosa

This study evaluated the impact of different concentrations of glyphosate (Rondup®) on planktonic and biofilm growth of P. aeruginosa. Aerobic and anaerobic cultures of P. aeruginosa ATCC®15442 inoculated in MHB + glyphosate (0.845 ppm, 1.690 ppm, 8.45 ppm, 16.90 ppm, 84.50 ppm, 169 ppm, 845 ppm, and 1690 ppm) and cultured in normoxia and anoxia, following their OD560nm every hour for 24 h. Biofilms of adapted cells were formed in the presence of glyphosate (0.845 to 1690 ppm) in normoxia and anoxia for 36 h. Glyphosate at concentrations higher than 84.5 ppm reduces the cell density of planktonic aerobic cultures (p < 0.05). However, these same concentrations favor the planktonic anaerobic growth (p < 0.05). On the other hand, the herbicide favors a slight growth of biofilms in a concentration-dependent manner up to 84.5 ppm (p > 0.05), and more pronounced over 169 ppm. Anaerobic biofilms have their growth more readily favored (p < 0.05), regardless of concentration. In a concentration-dependent manner, glyphosate interferes with the growth ability of P. aeruginosa ATCC®15442.

Prevalence of Pseudomonas aeruginosa and Acinetobacter spp. in subgingival biofilm and saliva of subjects with chronic periodontal infection

P. aeruginosa and Acinetobacter spp. are important pathogens associated with late nosocomial pneumonia in hospitalized and institutionalized individuals. The oral cavity may be a major source of these respiratory pathogens, particularly in the presence of poor oral hygiene and periodontal infection. This study investigated the prevalence of P. aeruginosa and Acinetobacter spp. in subgingival biofilm and saliva of subjects with periodontal disease or health. Samples were obtained from 55 periodontally healthy (PH) and 169 chronic periodontitis (CP) patients. DNA was obtained from the samples and detection of P. aeruginosa and Acinetobacter spp. was carried out by multiplex and nested PCR. P. aeruginosa and Acinetobacter spp. were detected in 40% and 45% of all samples, respectively. No significant differences in the distribution of these microorganisms between men and women, subgingival biofilm and saliva samples, patients < 35 and > 35 years of age, and smokers and non-smokers were observed regardless periodontal status (p > 0.05). In contrast, the frequencies of P. aeruginosa and Acinetobacter spp. in saliva and biofilm samples were significantly greater in CP than PH patients (p < 0.01). Smokers presenting P. aeruginosa and high frequencies of supragingival plaque were more likely to present CP than PH. P. aeruginosa and Acinetobacter spp. are frequently detected in the oral microbiota of CP. Poor oral hygiene, smoking and the presence of P. aeruginosa are strongly associated with periodontitis.

Lipolytic Activity and Molecular Identification of Pseudomonas aeruginosa and Lysinibacillus sphaericus Isolated from Domestic Oil Rich Wastewater.

Microbial lipases have been heightened in bioremediation and various industries. Place and Duration of Study: Department of Microbiology, Ekiti State University, Ado-Ekiti, Ekiti State, Nigeria, between September 2010 and August 2011. To identify the lipolytic enzyme producing microbial strains in domestic oil rich wastewater, the 16S rRNA gene was amplified and sequenced. The sequences were used to identify the strains by comparing with related sequences in database using BLAST analysis. The enzyme activity was quantified by HPLC analysis. All the lipolytic bacteria showed appreciable growth rates in the wastewater (between 0.67 and 1.67 mg/day) within 5 days. The most effective lipolytic bacteria isolates in the oil-rich wastewater were two species of the genus Pseudomonas and one of Bacillus. Comparing the weights on the first day to the twelfth day values when lipolytic organisms were grown in palm oil, some appreciable increases in weight difference were recorded in some isolates: 28.3%, 7.84%, 4.44% and 6.98% for Pseudomonas, Staphylococcus, Bacillus and Klebsiella, respectively. The weight increase of each of the microbial cells in palm oil culture was usually lesser than what was obtained in the oil-rich wastewater culture. Two isolates showed high similar sequence (99%) to that of Pseudomonas aeruginosa and Lysinibacillus sphaericus, respectively. From palm oil, Lysinibacillus sp. produced various forms of fatty acids in the medium, including myristic acid (2.61%), palmitic acid (6.22%), stearic acid (5.18%) and arachidic (3.66%). These strains are versatile in utilizing the limited nutrient and had the ability to grow appreciably in the toxic condition (soap solution), suggesting that they may serve as candidates in treating dietary oil-rich wastewater.

Actividad bactericida de superficies de cobre frente a bacterias asociadas a infecciones nosocomiales, en un modelo in vitro de adherencia y sobrevivencia / Adherence to copper and stainless steel metal coupons of common nosocomial bacterial strains

Background: Copper has a bactericidal activity against a series of bacterial strains. Aim: To measure resistance to bacterial adherence of copper (Cu) and stainless steel (SS) metal coupons. Material and Methods: Bacterial strains causing nosocomial infections in Chile were analyzed. Bacterial adherence was studied using apreviously described method based on a system of metal coupons that are immersed in culture media containing the bacteria ofinterest at room temperature. Results: Adherence to Cu and SS coupons was differentfor Methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae and Acinetobacter baumannii strains. For these strains, no adherence to Cu coupons occurred during the 48 h observation period compared to a rapidly increasing adherence to SS coupons, with a final colony count of 1.00E + 07 cfu/mL. For two different Pseudomonas aeruginosa clinical strains, inhibition of adherence was not observed on Cu coupons, and colony counts were similar for Cu and SS using the standard inoculum (2-3 xlO7 cfu).Apartial decrease in adherence was observed for Cu but not for SS coupons, when a lower inoculum was used. Conclusions: Copper surfaces represent an interesting option to reduce bacterial contamination in the hospital environment due to its resistance to bacterial adhesión ofmost ofthe common nosocomial bacterial strains.

Detección fenotípica de metalobetalactamasas en aislados clínicos de Pseudomonas aeruginosa / Phenotypic detection of metallo-beta-lactamase in clinical isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa, es considerado uno de los más importantes gérmenes hospitalarios, siendo común su aislamiento en pacientes hospitalizados, adicionalmente, este microorganismo presenta una marcada multiresistencia, lo que incrementa la mortalidad. El tratamiento de estos pacientes suele ser difícil, ya que además de su resistencia natural, Pseudomonas puede adquirir mecanismos de resistencia para prácticamente la totalidad de los antimicrobianos disponibles para su tratamiento, por lo que cada vez es más frecuente y necesario el empleo de antibióticos como los carbapenems, lo que facilita la adquisición de mecanismos de resistencia a estas drogas. El presente estudio intenta determinar la producción de metalobetalactamasas (MBL) en aislados clínicos de Pseudomonas aeruginosa, utilizando para ello dos métodos fenotípicos. Se utilizó el método del doble disco (MDD) y el test de Hodge modificado (MHT). Se analizaron 726 aislados clínicos de P. aeruginosa, el 20,11% (146) de estos fueron resistentes a imipenem (IPM) y meropenem (MEM), por lo que se les realizaron los dos métodos fenotípicos, de los 146 aislados resistentes a carbapenems, 139 fueron positivas para el MDD, mientras que 144 lo fueron para el MHT, estos dos métodos permitieron confirmar la presencia de una carbapenemasa tipo MBL en el 98,63% de los aislados de P. aeruginosa, por otra parte, cinco aislados no fueron positivos para el MDD pero si para el MHT, lo que indicaría la presencia de carbapenemasas no MBL en estos aislado, también se obtienen 2 aislados que a pesar de ser IPM y MEM resistentes fueron negativos por los dos métodos fenotípicos utilizados, esto indicaría la presencia de un mecanismo de resistencia no enzimático que confiere resistencia a carbapenems...

Pseudomonas aeruginosa is considered one of the most important hospital germs; its isolation is common in hospitalized patients. In addition, this microorganism has a marked multi-resistance, which increases mortality. Treatment of these patients is often difficult, since in addition to its natural resistance, Pseudomonas can obtain resistance mechanisms to virtually all antimicrobial drugs available for its treatment; due to this, its appearance is increasingly frequent and necessitates the use of antibiotics such as carbapenems, which facilitates the acquisition of resistance mechanisms to these drugs. This study attempts to determine the production of metallo-beta-lactamase (MBL) in clinical isolates of Pseudomonas aeruginosa, utilizing two phenotypic methods: the double disc method (MDD) and the modified Hodge test (MHT). 726 clinical isolates of P. aeruginosa were analyzed; 20.11% (146) of these were resistant to imipenem (IPM) and meropenem (MEM); 139 were positive for the MDD, while 144 were positive for the MHT. These two methods permitted confirming the presence of an MBL-type carbapenemase in 98.63% of P. aeruginosa isolates; five isolates were negative for the MDD but positive for the MHT, indicating the presence of non-MBL-type carbapenemase in these isolates. Also, 2 isolates were obtained that, despite being resistant to IPM and MEM, were negative according to the two phenotypic methods used; this would indicate the presence of a non-enzymatic resistance mechanism conferring resistance to carbapenems. The use of phenotypic methods for detecting MBL in P. aeruginosa isolates is quite an acceptable option for use in routine laboratories where specialized molecular biology tests are not available.

In vitro production of biofilm in a flow cell system in a strain of Pseudomonas aeruginosa and Staphylococcus aureus and determination of efficiency of ciprofloxacin against them.

Background: Microorganisms develop biofilm on various medical devices. The process is particularly relevant in public health since biofilm associated organisms are much more resistant to antibiotics and have a potential to cause infections in patients with indwelling medical devices. Materials and Methods: To determine the efficiency of an antibiotic against the biofilm it is inappropriate to use traditional technique of determining Minimum Inhibitory Concentration (MIC) on the free floating laboratory phenotype. Thus we have induced formation of biofilm in two strains (Pseudomonas aeruginosa and Staphylococcus aureus, which showed heavy growth of biofilm in screening by Tube method) in a flow cell system and determined their antibiotic susceptibility against ciprofloxacin by agar dilution method in the range (0.25 mg/ml to 8 mg/ml). The MIC value of ciprofloxacin for the biofilm produced organism was compared with its free form and a standard strain as control on the same plates. Observations: Both the biofilm produced strains showed a higher resistance (MIC > 8 mg/ml) than its free form, which were 2 μg/ml for Pseudomonas aeruginosa and 4 mg/ml for Staphylococcus aureus. Thus biofilm can pose a threat in the patient treatment.

Novel in vitro pharmacodynamic model simulating ofloxacin pharmacokinetics in the treatment of Pseudomonas aeruginosa biofilm-associated infections

The conventional in vitro models simulate pharmacodynamics of antibiotics in the treatment of planktonic Pseudomonas aeruginosa. In this study, we propose a novel pharmacodynamic model of ofloxacin activity in the treatment of P. aeruginosa biofilm. P. aeruginosa biofilm carrying coupons were suspended in a continuous flow central compartment bioreactor [CCB]. In the CCB, the pharmacokinetics of different ofloxacin dosing regimens were simulated. Samples from the coupons and the CCB were assessed for viability of the biofilm and the shedding planktonic cells, respectively, over 24 h. In addition, ofloxacin concentrations were assessed in each sample withdrawn for the CCB using bioassay method. The microbiological outcomes on P. aeruginosa biofilm and the shedding planktonic cells in response to different ofloxacin dosing regimens were not parallel and this may explain the non-coincidence of microbiological and clinical outcomes with biofilm associated infections. The current study has introduced unprecedented novel dynamic model for the assessment of the microbiological outcome on both biofilm and shedding planktonic cells of P. aeruginosa in response to different dosing regimens of ofloxacin which in turn can simulate the clinical outcomes in biofilm associated infections of P. aeruginosa, e.g. cystic fibrosis. Furthermore, different scenarios of antibiotic dosing regimens against biofilm related infections can be mimicked using such model

Biofilms: microbes and disease: [review]

Bacteria that attach to surface aggregate in a hydrated polymeric matrix of their own synthesis to form biofilms. These represent microbial societies with their own defense and communication system. Transitioning from acute to chronic infection is frequently associated with biofilm formation.Bacteria in biofilms are innately more resistant to antimicrobial agents. The presence of indwelling medical devices increases the risk for biofilm formation and subsequent infection. The current antibiotic therapies are of limited effectiveness in resolving biofilms infection.This review attempts to discuss the stages in biofilm formation, their pathogenic mechanisms, effect of antimicrobial agents, detection and eradication of the biofilms.

Effect of Pseudomonas aeruginosa on the giant freshwater prawn, Macrobrachium rosenbergii--histopathological and electron microscopic study.

The giant freshwater prawn Macrobrachium rosenbergii was injected with an inoculum containing LD, 96 hr dose of 10' Pseudomonas aeruginosa (MTCC 1688) to determine the histopathological effects in vivo. The comparison of tissues of both the control and the bacterial endotoxin treated prawns after 96 hr revealed significant degenerative changes in treated prawns. Both light microscopic and electron microscopic observations revealed the infiltration of the tissues of Pseudomonas sp in the muscular and hepatopancreatic tissues of prawn. The muscular tissue changes in the myofibrillar arrangement with blockage at the gap junctions and necrotic lesions were observed. The hepatopancreatic cells were vacuolated with hypertrophied nucleus. Atrophy of hepatopancreatic tubules was conspicuous. The pathogenicity of Pseudomonas aeruginosa is attributed to its infiltration and multiplication inside the tissues and the consequent release of extra-cellular enzymes for its metabolism. The degeneration of host tissues is also attributed to the latter.

Catheter related bacteremia in rats: A preliminary report on the effect of methylene blue coated catheter.

The safety and efficacy of methylene blue (MB) coated indwelling jugular vein/cranial vena cava catheter made up of polyurethane material was tested in a rat model, receiving bacterial culture suspension of Pseudomonas aeruginosa, and Staphylococcus aureus. Daily blood samples were collected from the catheter and peripheral vein for bacterial culture. The clinical parameters (rectal temperature, respiratory rate, total white blood cell count, and loss in body weight) were not different between the groups. All the rats became bacteremic with similar changes in the number of colony forming units in the catheter and peripheral samples. Histopathological lesions were not different between the groups. The findings suggest that rats receiving MB coated catheters behaved similar to non-coated catheters. Based on the results it can be concluded that for this type of gross contamination, catheter coating alone may not eliminate infection/bacteremia.

Estudo da virulência de amostras de Pseudomonas aeruginosa: comparaçäo de amostras isoladas de microflora normal e de infecçöes humanas / Virulence of strains of Pseudomonas aeruginosa: comparison of isolated strains of the normal microflora and of human infections

Foram estudadas, comparativamente, 33 amostras de Pseudomonas aeruginosa isoladas de microflora normal do orofaringe e de infecçöes humanas, usando-se marcadores de virulência in vitro. O teste de sensibilidade ao cloreto de benzalcônio, quando empregado isoladamente, foi ineficaz como marcador de virulência e mostrou correlaçäo quando em conjunto com o teste de produçäo de enzimas

Estudio de la movilidad y velocidad bacteriana empleando televisión en circuito cerrado / Study of bacterial motility and rate of movement using a closed circuit television

Speed and motion patterns of Canpylobacter fetus ssp. jejuni, Escherichia coli and Pseudomonas aeruginosas were recorded using a closed circuit television camera attached to a phase contrast microscope. A Sony video analysis system was used to stop frame videotape at 1/7th and 1/15th. Bacterial speeds were: Campylobacter 29.2 µm/s and P. aeruginosa 16.8 µm/s