Activity and interactions of antibiotic and phytochemical combinations against Pseudomonas aeruginosa in vitro

In this study the in vitro activities of seven antibiotics (ciprofloxacin, ceftazidime, tetracycline, trimethoprim, sulfamethoxazole, polymyxin B and piperacillin) and six phytochemicals (protocatechuic acid, gallic acid, ellagic acid, rutin, berberine and myricetin) against five P. aeruginosa isolates, alone and in combination are evaluated. All the phytochemicals under investigation demonstrate potential inhibitory activity against P. aeruginosa. The combinations of sulfamethoxazole plus protocatechuic acid, sulfamethoxazole plus ellagic acid, sulfamethoxazole plus gallic acid and tetracycline plus gallic acid show synergistic mode of interaction. However, the combinations of sulfamethoxazole plus myricetin shows synergism for three strains (PA01, DB5218 and DR3062). The synergistic combinations are further evaluated for their bactericidal activity against P. aeruginosa ATCC strain using time-kill method. Sub-inhibitory dose responses of antibiotics and phytochemicals individually and in combination are presented along with their interaction network to suggest on the mechanism of action and potential targets for the phytochemicals under investigation. The identified synergistic combinations can be of potent therapeutic value against P. aeruginosa infections. These findings have potential implications in delaying the development of resistance as the antibacterial effect is achieved with lower concentrations of both drugs (antibiotics and phytochemicals).     

The effects of some formulation factors used in ophthalmic preparations on thiomersal activity against Pseudomonas aeruginosa and Staphylococcus aureus

AIMS: To investigate the effects of formulation ingredients used in ophthalmic preparations on thiomersal activity against Staphylococcus aureus and Pseudomonas aeruginosa. METHODS AND RESULTS: Minimum inhibition concentrations (MICs) of the tested ingredients and their combinations were studied using partial broth dilution checkerboard method. Complex formation was determined using differential scanning calorimetry (DSC) and u.v. scan. Isotonic agents showed insignificant difference in thiomersal activity. Low concentrations of propylene glycol and glycerol (2 to about 6.5%) significantly reduced the activity of thiomersal against P. aeruginosa. Higher concentrations up to about 40%, of the two cosolvents did not affect the antibacterial activity. Viscosity increasing agents significantly reduced the antibacterial activity of thiomersal. Low concentrations of 0.05% and 0.05-0.1% of ethylenediaminetetraacetic acid resulted in a significant decrease in thiomersal activity against S. aureus and P. aeruginosa, respectively. However, concentrations above 0.25 and 0.5 up to 4% caused significant increase on the antibacterial activity against the two later micro-organisms, respectively. CONCLUSIONS: Results showed that thiomersal formed complexes with ingredients containing polyhydroxy groups and chelating agents, thus thiomersal is not recommended to be used with such ingredients. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlighted the importance of proper selection of ingredients and preservatives for ophthalmic preparations.     

铜绿假单胞菌医院感染分布及耐药性分析

目的探讨铜绿假单胞菌临床分离株的感染分布情况及其抗生素的耐药情况,指导临床合理用药。方法对我院2006年1月至2008年6月住院患者分离的铜绿假单胞菌进行抗生素敏感性测定,采用API系统及VITEK2系统进行细菌鉴定,用K-B法进行药敏试验及结果观察。结果216例院内感染铜绿假单胞菌病例中,从痰标本中分离的菌株最多,阳性率为45．4％;铜绿假单胞菌对头孢噻肟、复方新诺明、头孢哌酮的耐药率较高,分别为88％、86．1％和85．2％,对美洛培南的敏感性最高达到94％。结论铜绿假单胞菌是医院病原菌感染的主要致病菌之一,加强细菌和药敏监测,选择敏感性强的药物,避免广谱抗菌药物的长期应用,是延缓耐药菌株增加的有效办法。     

椒样薄荷、薄荷和苏格兰留兰香精油与抗生素的协同抑菌功能

以开花期的椒样薄荷（Mentha×piperita）、薄荷（M.haplocalyx）和苏格兰留兰香（M.×gentilis）叶片部位提取的精油为研究对象,通过GC-MS分析,并采用纸片扩散法研究了3种精油单独使用及与抗生素联合使用时对金黄色葡萄球菌、蜡状芽孢杆菌、大肠杆菌、绿脓杆菌和肺炎克雷伯氏菌的抑制情况。结果表明,（1）椒样薄荷与薄荷精油中含量最高的成分为薄荷醇、薄荷酮和异薄荷酮,苏格兰留兰香精油的主要成分为香芹酮和柠檬烯。薄荷和苏格兰留兰香精油符合欧洲药典与ISO标准,椒样薄荷需要继续改良以提高其精油品质与抑菌功能。（2）精油单独使用时,Pseudomonas aeruginosa ATCC15442对椒样薄荷精油和薄荷精油敏感;P.aeruginosa ATCC27853对薄荷精油和苏格兰留兰香精油敏感。精油与抗生素联合使用时抑菌范围和强度均有所改变：绿脓杆菌的2个菌株对精油与抗生素的组合最为敏感,其中,椒样薄荷精油与头孢他啶的组合对P.aeruginosa ATCC15442显示出最强的增效作用,薄荷精油与头孢他啶混合之后对P.aeruginosa ATCC27853出现拮抗作用。Staphylococcus aureus ATCC25923对所有精油以及精油与抗生素混合物均有抗性。（3）椒样薄荷、薄荷和苏格兰留兰香精油的不同成分及其含量差异不仅对精油品质有影响,而且影响精油对测试菌种的抑制作用,可考虑将其作为薄荷属植物品质育种的参考指标。     

Fluoroquinolones and their importance in modern chemotherapy of infectious diseases

Experimental and clinical data on antibacterial drugs belonging to fluorine derivatives of quinolone carboxylic acid (quinolones of the third generation) were summarized. Brief characteristics of their antibacterial activity and experimental data on chemotherapeutic activity of pefloxacin, a fluoroquinolone on models of septicopyemia and meningoencephalitis in experiments with mice infected by P. aeruginosa, Staphylococcus and Klebsiella are presented. High efficacy of pefloxacin was shown and its advantages over dioxidine and gentamicin on the model of meningoencephalitis were revealed. The main indications to the use of fluoroquinolones, possible adverse reactions and contraindications to the use of the drugs of that group are described.     

In vitro interaction between mecillinam and piperacillin-tazobactam in the presence of azithromycin against members of the Enterobacteriaceae family and Pseudomonas aeruginosa

Mecillinam was tested in vitro alone or in combination with piperacillin-tazobactam and azithromycin against representative species of the Enterobacteriaceae family and Pseudomonas aeruginosa to extend its antibacterial spectrum, and to protect mecillinam from inactivating enzymes taking advantage of the presence of tazobactam. Drug interactions were studied by microdilution method, by selection of spontaneous resistant mutants on agar plates containing the drugs in combination and by time kill experiments. Against Enterobacteriaceae mecillinam and piperacillin-tazobactam showed synergistic interaction in 24/60 tests carried out by microdilution technology, in 4/16 by selecting resistant mutants and in 5/9 by time-kill experiments. P. aeruginosa reacted indifferently to the drug combinations, with few exceptions, when azithromycin was present a reduction of the MICs were recorded. Mecillinam reacted favourably in vitro in combination with piperacillin-tazobactam against not only strains included in its antibacterial spectrum but also against resistant Morganella morganii, Proteus spp and P. aeruginosa. The addition of azithromycin (8 mg/L) was beneficial for the drug combination increasing the bactericidal effect in the great majority of the cases. Only systematic in vivo studies may establish the clinical significance and benefits of the present observations.     

椒样薄荷、薄荷和苏格兰留兰香精油与抗生素的协同抑菌功能

以开花期的椒样薄荷(Mentha × piperita)、薄荷(M. haplocalyx)和苏格兰留兰香(M. × gentilis)叶片部位提取的精油为研究对象, 通过GC-MS分析, 并采用纸片扩散法研究了3种精油单独使用及与抗生素联合使用时对金黄色葡萄球菌、蜡状芽孢杆菌、大肠杆菌、绿脓杆菌和肺炎克雷伯氏菌的抑制情况。结果表明, (1) 椒样薄荷与薄荷精油中含量最高的成分为薄荷醇、薄荷酮和异薄荷酮, 苏格兰留兰香精油的主要成分为香芹酮和柠檬烯。薄荷和苏格兰留兰香精油符合欧洲药典与ISO标准, 椒样薄荷需要继续改良以提高其精油品质与抑菌功能。(2) 精油单独使用时, Pseudomonas aeruginosa ATCC 15442对椒样薄荷精油和薄荷精油敏感; P. aeruginosa ATCC 27853对薄荷精油和苏格兰留兰香精油敏感。精油与抗生素联合使用时抑菌范围和强度均有所改变: 绿脓杆菌的2个菌株对精油与抗生素的组合最为敏感, 其中, 椒样薄荷精油与头孢他啶的组合对P. aeruginosa ATCC 15442显示出最强的增效作用, 薄荷精油与头孢他啶混合之后对P. aeruginosa ATCC 27853出现拮抗作用。Staphylococcus aureus ATCC 25923对所有精油以及精油与抗生素混合物均有抗性。(3) 椒样薄荷、薄荷和苏格兰留兰香精油的不同成分及其含量差异不仅对精油品质有影响, 而且影响精油对测试菌种的抑制作用, 可考虑将其作为薄荷属植物品质育种的参考指标。     

Comparison of silver sulfadiazine and gentamicin for topical prophylaxis against burn wound sepsis.

Daily prophylactic application of either 1.0% silver sulfadiazine cream or 0.1% gentamicin cream was compared for effectiveness in preventing bacterial colonization of burn wounds and sepsis. Pseudomonas aeruginosa colonized the wounds of 37% of the 38 patients treated with silver sulfadiazine and 30% of the 33 patients treated with gentamicin; gentamicin-resistant P. aeruginosa colonized the wounds of 21% of the patients treated with gentamicin. Staphylococcus aureus colonization occurred in 55% of the patients treated with silver sulfadiazine, whereas colonization with Candida species occurred in 58% of the patients treated with gentamicin. Although gentamicin-resistant organisms caused no deaths their repeated appearance resulted in discontinuation of prophylaxiz with gentamicin cream. The next year P. aeruginosa strains resistant to gentamicin were isolated from burn wounds of only two patients who had not previously received parenteral therapy with gentamicin or tobramycin. Gentamicin cream should be reserved for treating patients with wounds infected by gentamicin-sensitive P. aeruginosa and those allergic to sulfa drugs. For most patients with burn wounds silver sulfadiazine is safe and effective as an antibacterial agent for topical prophylaxis.     

Effect of temperature on antibacterial activity of lidocaine to Staphylococcus aureus and Pseudomonas aeruginosa

The effect of temperature on the antibacterial activity of lidocaine to Staphylococcus aureus and Pseudomonas aeruginosa was investigated in vitro. At 10 C at which S. aureus organisms do not grow and might be metabolically inactive, the antibacterial activity of lidocaine to S. aureus was not observed in a concentration of 1%, which was quite antibacterial to S. aureus at 37 C. On the other hand, at 40 C a conspicuously increased antibacterial activity to S. aureus of lidocaine was observed in a concentration of 0.25% which was not antibacterial to S. aureus organisms at 37 C. Similar results were obtained when P. aeruginosa organisms were examined in place of S. aureus, although P. aeruginosa was found to be less susceptible to lidocaine than S. aureus. The clinical significance of the thermal effect on the antibacterial activity of lidocaine was discussed in brief.     

铜绿假单胞菌抗菌物质对耐甲氧西林金黄色葡萄球菌的抑菌活性研究

目的观察铜绿假单胞菌抗菌物质对耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcusaureus,MRSA)的体外抑菌活性。方法用交叉划线接种方法进行铜绿假单胞菌对32株耐甲氧西林金葡菌的体外抗菌活性的测定。结果铜绿假单胞菌抗菌物质对MRSA的体外抑菌活性良好,产生色素的菌株的抗菌活性最好,15株铜绿假单胞菌中,7株产蓝绿色色素的铜绿假单胞菌,对MRSA的抑制率均达到了100%,平均抑菌带的宽度为37.7 mm。结论铜绿假单胞菌抗菌物质对32株MRSA具有较强的抗菌活性,无疑对MRSA感染的抗菌药物研制方面开辟了一条新的途径。这是国内的首次研究报道。     

不同标本来源铜绿假单胞菌体外耐药性对比研究

目的比较不同部位培养出的铜绿假单胞菌耐药性,为临床控制和治疗铜绿假单胞菌感染提供依据。方法收集住院患者不同标本中分离的铜绿假单胞菌进行鉴定和药敏试验。结果分离率以痰标本中最高,占57.67%;伤口分泌物次之占30.69%。科室分布以ICU（38.1%）、神经外科（15.34%）和烧伤科（14.81%）最多见。同一种抗菌药物对不同标本分离的铜绿假单胞菌显示出不同敏感性,痰标本中铜绿假单胞菌对常用抗菌药物耐药率较伤口分泌物标本中高,除头孢哌酮/舒巴坦、氨苄西林/舒巴坦和复方新诺明外,对其他常用的12种抗菌药物耐药率比较差异有统计学意义（P〈0.05）。结论不同标本分离的铜绿假单胞菌对抗菌药物耐药性存在差异,临床经验用药时应区别对待不同部位铜绿假单胞菌的感染。     

Distinct synergistic action of piperacillin and methylglyoxal against Pseudomonas aeruginosa

The dicarbonyl compound methylglyoxal is a natural constituent of Manuka honey produced from Manuka flowers in New Zealand. It is known to possess both anticancer and antibacterial activity. Such observations prompted to investigate the ability of methylglyoxal as a potent drug against multidrug resistant Pseudomonas aeruginosa. A total of 12 test P. aeruginosa strains isolated from various hospitals were tested for their resistances against many antibiotics, most of which are applied in the treatment of P. aeruginosa infections. Results revealed that the strains were resistant to many drugs at high levels, only piperacillin, carbenicillin, amikacin and ciprofloxacin showed resistances at comparatively lower levels. Following multiple experimentations it was observed that methylglyoxal was also antimicrobic against all the strains at comparable levels. Distinct and statistically significant synergism was observed between methylglyoxal and piperacillin by disc diffusion tests when compared with their individual effects. The fractional inhibitory concentration index of this combination evaluated by checkerboard analysis, was 0.5, which confirmed synergism between the pair. Synergism was also noted when methylglyoxal was combined with carbenicillin and amikacin.     

铜绿假单胞菌体外抑菌活性研究

目的 观察铜绿假单胞菌抗菌物质对鲍曼不动杆菌等细菌的体外抑菌效果.方法 用交叉条带实验方法检测了铜绿假单胞菌对鲍曼不动杆菌、耐甲氧西林表皮葡萄球菌和粪肠球菌的体外抑制活性.结果 铜绿假单胞菌对鲍曼不动杆菌、耐甲氧西林表皮葡萄球菌和粪肠球菌体外抑菌活性良好,10株铜绿假单胞菌中,有8株对鲍曼不动杆菌的抑制率均达到了100％.另外有8株对耐甲氧西林表皮葡萄球菌的抑菌率均为100％;有6株对粪肠球菌的抑菌率为100％.结论 铜绿假单胞菌对上述3种致病菌具有较强的抗菌活性,具有开发前景.     

自然感染方法诱导蝇蛆抗菌活性研究

研究通过自然感染方法诱导的丝光绿蝇蛆虫的抗菌活性.用大肠埃希菌感染无菌蛆虫,用灭菌的PBS作为对照.提取血淋巴,以金黄色葡萄球菌、绿脓杆菌作指示菌,采用平板法作抑菌试验,检验蛆虫血淋巴的抗菌活性.结果发现:感染的蛆虫比无菌蛆虫有较好的抗菌能力;大肠埃希菌预处理12 h后能够诱导蛆虫的抗菌活性,在24h达到峰值然后下降;血淋巴对金黄色葡萄球菌的抗菌活性高于绿脓杆菌.研究表明,通过自然感染的方法可以诱导丝光绿蝇幼虫抗菌活性.     

Drug susceptibility of Pseudomonas aeruginosa strains isolated from patients of a hospital and specialistic outpatients clinics of the SP ZOZ in Nidzica

The aim of this study was to evaluate a frequency of isolation and antimicrobial susceptibility testing (AST) of Pseudomonas aeruginosa strains cultured from clinical specimens collected from patients hospitalized in wards and specialistic outpatients clinics of a hospital in Nidzica (01. 09. 2000 -31. 12. 2003). During over three years 392 Pseudomonas aeruginosa strains were cultured from 16346 clinical samples provided to bacteriological laboratory. P. aeruginosa strains were isolated from 2.5% of examined specimens. Susceptibility of Pseudomonas aeruginosa strains to antimicrobial agents was tested. The highest in vitro activity against clinical P. aeruginosa strains demonstrated imipenem. One strain was resistant to imipenem. This strain was isolated from a patient of a surgical department. Metalo-beta-lactamase was not detected (MBL-negative strain).Twenty nine strains were ESBL producer (7.4% of all strains). The contribution of Pseudomonas aeruginosa strains to the etiology of nosoconial and ambulatory infections increases. In vitro activity of antibacterial agents against P. aeruginosa strains should be monitored during therapy of infections. Resistance to antibiotics/chemothe-rapeutics may be acquired during treatment with antibacterial agent to which P. aeruginosa strain was susceptible according to the antibiogram.     

Inflammatory markers in cystic fibrosis patients with lung Pseudomonas aeruginosa infection

Chronic endobronchial inflammation and bacterial infection are the main causes of morbidity and mortality in cystic fibrosis (CF), an autosomal recessive genetic disorder associated with improper function of chloride channels. Inflammation in CF lung is greatly amplified after Pseudomonas aeruginosa infection. In this study the relationship between P. aeruginosa status and inflammatory markers has been investigated. Seventeen CF children in acute lung exacerbation were examined. CF patients without P. aeruginosa infection were characterized by elevated activity of sputum elastase, reduced response of peripheral blood lymphocytes to PHA and significant resistance to the antiproliferative action of glucocorticoids. These parameters were normalized after antibiotic treatment. The patients with prolonged P. aeruginosa infection demonstrated extremely high levels of elastase activity and elevated amounts of sputum IL-8 and TNF-alpha. Although antibiotic treatment resulted in clinical improvement, it failed to suppress excessive immune response in the lung. The data indicate that CF patients with prolonged P. aeruginosa need the modified treatment, which should include immunomodulating drugs and protease inhibitors as well as antibacterial therapy.     

Comparative studies of penicillin-binding proteins in Pseudomonas aeruginosa and Escherichia coli.

Penicillin-binding proteins in Pseudomonas aeruginosa were compared with those of Escherichia coli. These in P. aeruginosa were found exclusively in the cytoplasmic membrane fraction (fraction soluble in sodium N-lauroyl sarcosinate). Sodium dodecyl sulfate/acrylamide gel electrophoresis of the proteins bound to [14C]penicillin G resulted in the separation of six major bands and several minor bands. The proteins in these bands are referred to as proteins 1A, 1B, 2, 3, 4 and 5 in order of increasing electrophoretical mobility. The electrophoretic mobilities and other properties of penicillin-binding proteins in P. aeruginosa and E. coli were compared and correlated. Fundamentally they seem to be very similar in the two bacteria, but proteins 1A and 1B in P. aeruginosa seem to correspond respectively to proteins 1B and 1A in E. coli, and protein 6 seems to be missing or present in only small amount in P. aeruginosa. In addition, the affinities of currently developed beta-lactam antibiotics to each protein of P. aeruginosa and E. coli were examined in relation to the morphological changes of the cells induced by these antibiotics and their antibacterial potencies. Mecillinam showed high affinity to only protein 2 in both P. aeruginosa and E. coli. At a minimal inhibitory concentration, it converted cells of both P. aeruginosa and E. coli from rods to spherical cells, although its minimal inhibitory concentration was much higher for P. aeruginosa than for E. coli.     

Biosynthesis of 6-deoxyhexose glycans in bacteria

After the breakthroughs in genomic sequencing, one of the next challenges remains to understand the molecular biology of other classes of biomolecules, such as protein and lipids, many of which carry specific glycomodification when mediating their biological functions. This review focuses on the 6-deoxyhexose biosynthesis of cell surface glycans of three Gram-negative pathogens, Helicobacter pylori, Pseudomonas aeruginosa, and Actinobacillus actinomycetemcomitans serotype a. 6-Deoxysugars are important functional components of cell surface glycans, and their biosynthetic pathways might be suitable targets for novel interventions of antibacterial chemotherapy.     

Antibacterial activity of crude methanolic extract and its fractions of aerial parts of Anthemis tinctoria

The antibacterial activity of the methanolic extract and its fractions of aerial parts of Aniheinis tinctoria (Asteraceae) was investigated against representative gram-positive Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 29212) and gram-negative strains Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). The activity was concentrated mainly in the dichloromethane (DCM) and hexane fractions of crude methanolic extract. The 5 mg of DCM extract per disk produced 15-16 mm of inhibition zone against S. aureus and P. aeruginosa, however, no activity was found against E. faecalis and E. coli. The hexane fraction showed activity against S. aureus, P. aeruginosa and E. faecalis. As DCM fraction showed the highest antibacterial activity in the disk diffusion assay, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of only this fraction was determined against S. aureus and P. aeruginosa. These values were found to be in the range of 1.25 to 10 mg/ml.     

Development of a CrN/Cu nanocomposite coating on titanium-modified stainless steel for antibacterial activity against Pseudomonas aeruginosa

A relatively simple method was developed to fabricate CrN/Cu nanocomposite coatings using pulsed DC magnetron sputtering for application in antibacterial activity. These nanocomposite coatings were applied on titanium (Ti)-modified stainless steel substrata (D-9 alloy) and the antibacterial activity of these coating with respect to the Gram-negative bacterium Pseudomonas aeruginosa was investigated qualitatively and quantitatively. Scanning electron microscopy, epifluorescence microscope analyses, and total viable counts confirmed that inclusion of copper in the CrN/Cu nanocomposite coatings provided antibacterial activity against P. aeruginosa. The quantitative examination of the bacterial activity of P. aeruginosa was estimated by the survival ratio as calculated from the number of viable cells which formed colonies on nutrient agar plates.