Pectinolytic enzymes of anaerobic fungi

Pectinolytic enzymes of four rumen fungi have been described. Three fungal species were monocentric Neocallimastix spp. H15, JL3 and OC2, and one isolate was a polycentric strain of Orpinomyces joyonii , A4. They differed in degree of pectin degradation and utilization. Only the strain Neocallimastix sp. H15 and partially Orpinomyces joyonii A4 were able to utilize pectin to a higher extent. The most important pectinolytic activity in all these isolates represented pectin lyase (EC 4.2.2.10) and polygalacturonase (EC 3.2.1.15). Their specific activities were in the range of 100–900 and 10–450 μg galacturonic acid h^-1 mg protein^-1 for pectin lyase and polygalacturonase, respectively. Polygalacturonase, located mainly in the endocellular fraction, was inhibited by calcium ions and had the main pH optimum at pH 6.0. All strains produced pectate lyase (EC 4.2.2.2). None of the strains tested produced pectinesterase (EC 3.1.1.11).     

Urease-mediated destruction of bacteria is specific for Helicobacter urease and results in total cellular disruption

Abstract The survival of Helicobacter mustelae, Proteus mirabilis, Escherichia coli and Campylobacter jejuni in the presence of urea and citrate at pH 6.0 was examined. H. mustelae , which has urease activity similar to H. pylori , had a markedly reduced survival, median 2.5% (0–78%) ( P <0.001) when incubated nder these conditions. Only 7% of the ammonia produced by H. mutelae urease activity was recovered from the buffer, a similar percentage to that previously reported with H. pylori . None of the other organisms, all of which had lower urease activity, had impaired survival under these conditions. Electron microscopical studies demonstrated extensive structural damage to H. pylori following exposure to urea and citrate at pH 6.0. This structural damage to the organisms makes it unlikely that the low recovery of ammonia was due to retention of ammonia within the bacteria and suggests that the ammonia may have been incorporated into glutamate or other amino acids. Incorporation of ammonia into these compounds would deplete the cell of the key metabolic intermediate α-ketoglutarate and could thus explain the mechanism of the urease-dependent destruction of the organism.     

Thermophilic bacteria that tolerate a wide temperature and pH range colonize the Soldhar (95 °C) and Ringigad (80 °C) hot springs of Uttarakhand,India

Twenty-eight bacterial cultures, isolated from hot springs in Uttarakhand, were characterized with particular reference to their wide temperature and pH tolerance and production of enzymes in the thermophilic range. All the bacterial isolates were observed as Gram-positive or variable rods in varied arrangement. Bacterial isolates exhibited tolerance to a wide temperature range (20–80 °C), from mesophilic (+11° to +45 °C) to thermophilic (+46 ° to +75 °C); few almost reached the hyperthermophilic range (+76 °C). The isolates also tolerated a wide pH range (4–14) and moderate salt concentration. The optimum growth of the bacterial isolates was observed at 55 °C and 7 pH. Out of 28 isolates, 25 produced lipase, 25 amylase, 24 cellulase, 22 protease and 13 xylanase at 55 and 65 °C. Tolerance to a wide temperature and pH range and the production of enzymes in a thermophilic temperature range can be considered as indicators of ecological competence of these bacterial isolates for colonizing the high temperature environment. On the basis of 16S rDNA similarity, 20 bacterial isolates belonged to Bacillus licheniformis, five to Paenibacillus ehimensis and one each to Bacillus sonorensis, B. tequilensis, and Staphylococcus epidermidis. Besides variation in phenotypic characters, strains of B. licheniformis and P. ehimensis showed varying 16S rDNA similarity between 97–99 % and 95–99 %, respectively. Consideration of temperature preferences in classifying microorganisms on the basis of their minimum, maximum, and optimum growth requirements is also discussed. The study has ecological relevance in the context of colonization of high temperature environments by thermophilic bacteria.     

Isolation and characterization of plant growth-promoting strain Pantoea NII-186. From Western Ghat Forest soil, India

Aims:  To isolate plant growth-promoting bacterium from Western Ghat forests in India.
Methods and Results:  A Gram-negative, rod shaped, cream white coloured strain Pantoea NII-186 isolated from Western Ghat soil sample. The taxonomic position of the bacterium was confirmed by sequencing of 16S rRNA and phylogenetic analysis. A strain grew at a wide range of temperature ranging from 5–40°C, but optimum growth was observed at 28–30°C. It showed multiple plant growth-promoting attributes such as phosphate solubilization activity, indole acetic acid (IAA) production, siderophore production and HCN production. It was able to solubilize (28 μg of Ca₃PO₄ ml⁻¹ day⁻¹), and produce IAA (59 μg) at 28°C. The solubilization of insoluble phosphate was associates with a drop in the pH of the culture medium. Pantoea sp. NII-186 tolerate to different environmental stresses like 5–40°C, 0–7% salt concentration and 4–12 pH range.
Conclusions:  The 16S rRNA gene sequence confirmed that the isolate NII-186 was belongs to Pantoea genus and showed considerable differences in physiological properties with previously reported species of this genus. Isolate NII-186 possessed multiple attributes of plant growth-promoting activity.
Significance and Impact of the Study:  Hence in the context it is proposed that Pantoea sp. NII-186, could be deployed as an inoculant to attain the desired plant growth-promoting activity in agricultural environment.     

Cold,pH and salt tolerant Penicillium spp. inhabit the high altitude soils in Himalaya,India

Twenty five fungal cultures (Penicillium spp.), isolated from soil samples from the high altitudes in the Indian Himalayan region, have been characterized following polyphasic approach. Colony morphology performed on five different media gave varying results; potato dextrose agar being the best for the vegetative growth and sporulation as well. Microscopic observations revealed 18 isolates to be biverticillate and 7 monoverticillate. Based on the phenotypic characters (colony morphology and microscopy), all the isolates were designated to the genus Penicillium. Exposure to low temperature resulted in enhanced sporulation in 23 isolates, while it ceased in case of two. The fungal isolates produced watery exudates in varying amount that in many cases increased at low temperature. All the isolates could grow between 4 and 37 °C, (optimum 24 °C), hence considered psychrotolerant. While all the isolates could tolerate pH from 2 to 14 (optimum 5–9), 7 isolates tolerated pH 1.5 as well. While all the fungal isolates tolerated salt concentration above 10 %; 10 isolates showed tolerance above 20 %. Based on ITS region (ITS1-5.8S-ITS2) analysis the fungal isolates belonged to 25 different species of Penicillium (showing similarity between 95 and 100 %). Characters like tolerance for low temperature, wide range of pH, and high salt concentration, and enhancement in sporulation and production of secondary metabolites such as watery exudates at low temperature can be attributed to the ecological resilience possessed by these fungi for survival under low temperature environment of mountain ecosystem.     

Volatile compounds associated with microbial growth on normal and high pH beef stored at chill temperatures

Volatile compounds produced by Pseudomonas fragi and mixed, natural floras on beef of normal pH (5–5–5–8; glucose < 1500 μg/g) and high pH (6–3–6–8; glucose < 10 μg/g) included a range of alkyl esters and a number of sulphur-containing compounds including dimethylsulphide but not hydrogen sulphide. Production of the last was a property common to the other Gram-negative organisms tested viz. Hafnia alvei, Enterobacter agglomerans, Serratia liquefaciens, Alteromonas putrefaciens and Aeromonas hydrophila , all of which produced similar off-odours and, with the exception of E. agglomerans , 'greening'on high pH meat. Serratia liquefaciens also produced greening of normal pH meat. Acetoin and diacetyl were major end products of Brochothrix thermosphacta but the related 2,3-butanediol was formed only on normal pH meat. The Enterobacteriaceae produced the same compounds but only on normal pH meat and together with Br. thermosphacta were probable sources of these compounds and of the free and esterified branched-chain alcohols detected in the naturally contaminated samples.     

Some environmental factors affect growth and antibiotic production by the mycoparasite Coniothyrium minitans

The effects of temperature and pH on growth and antibiotic production by three isolates of Coniothyrium minitans (Conio, Contans and IVT1), known to produce the macrolide antibiotic macrosphelide A, were examined in modified Czapek Dox broth (MCD). Antibiotic production was determined by incorporating heated (60°C for 5 min) C. minitans spent culture filtrates of MCD (10%, v/v) into potato dextrose broth and assessing the ability of the filtrates to inhibit growth of S. sclerotiorum. All isolates grew over the temperature range of 10–30°C, with the optimum at approximately 15–20°C. Antibiotics were produced by all isolates at 10–30°C. Culture filtrates of MCD from all isolates incorporated into PDB inhibited growth of S. sclerotiorum by >50%, whereas there was a reduction in inhibition at 30°C for Conio and IVT1 but not Contans. All three isolates grew over the pH range of 3–7, with greater biomass production in buffered pH 3–5 than the unbuffered control (pH 4.8) media. Antibiotics were produced by all isolates at pH 3–5. Culture filtrates of MCD from all three isolates grown at pH 3–5 inhibited growth of S. sclerotiorum, with the greatest effect on inhibition observed at pH 3. There were no differences in growth inhibition between isolates at pH 3 and 4, but culture filtrates from Conio grown at pH 5 inhibited S. sclerotiorum more than those of IVT1 grown at the same pH. The significance of these results for biocontrol and optimizing antibiotic production by C. minitans is discussed.     

Anti-Helicobacter pylori activity of Lactobacillus delbrueckii subsp. bulgaricus strains: preliminary report

Aims:  To evaluate the activities of six Lactobacillus delbrueckii subsp. bulgaricus (LB) strains against 30 Helicobacter pylori strains by agar-well diffusion method.
Methods and Results:  LB cultures [4 × 10⁸–4 × 10⁹ CFU ml⁻¹) either were prepared in milk at their native pH, 3·8–5·0, or were adjusted to pH 6·4–7·7. At low and neutralized pH, LB strains inhibited the growth by 40–86·7% and 16·7–66·7% of H. pylori strains, respectively. LB activity was strain-dependent. At low and neutralized pH, one and five H. pylori strains, respectively, were not inhibited by any LB strain. LB2 and LB3, taken together, were active against most metronidazole and clarithromycin resistant strains.
Conclusions:  All LB strains inhibited a number of H. pylori strains, including also antibiotic resistant strains. LB activity was strain-dependent and better at low pH. At low pH values, the most active LB strains were LB1, LB2 and LB3, inhibiting 86·7% of H. pylori strains, while at neutralized pH values, the most active LB strains were LB2 and LB3, inhibiting 53·3 and 66·7% of H. pylori strains, respectively.
Significance and Impact of the Study:  LB could be utilized in the treatment or prophylaxis of H. pylori infection and warrants clinical investigations.     

Thermophilic protease-producing Geobacillus from Buranga hot springs in Western Uganda

Two proteolytic thermophilic aerobic bacterial strains, PA-9 and PA-5, were isolated from Buranga hot springs in western Uganda. The cells were rods, approximately 10–12 μm in length and 3 μm in width. Isolate PA-9 grew at between 38°C and 68°C (optimum, 62°C), and PA-5 grew at between 37°C and 72°C (optimum, 60°C). Both isolates grew optimally at pH 7.5–8.5. Their 16S rRNA gene sequences indicated that they belong to the newly described genus Geobacillus. Zymogram analysis of the crude enzyme extracts revealed the presence of two extracellular proteases for isolate PA-5, and at least eight for isolate PA-9. The optimum temperature and pH for casein-degrading activity were 70°C, pH 6.5 for isolate PA-9, but caseinolytic activity could also be observed at 2°C. In the case of isolate PA-5, optimal activity was observed over a temperature and pH range of 50–70°C and pH 5–10, respectively. Received: 26 November 2001 / Accepted: 12 December 2001     

高产纤维素酶枯草芽胞杆菌S-16的筛选及其发酵工艺优化

利用刚果红鉴别培养基及基础液体筛选培养基进行菌种筛选,从新疆盐碱地分离得到的16株菌株中筛选获得一株产纤维素酶活力较高的菌株S-16,对该菌株进行16SrDNA鉴定,确定该菌为枯草芽胞杆菌(Bacillus subtilis)。对S-16发酵产纤维素酶的主要影响因素进行研究,分别考察了碳源、氮源、培养基初始pH和接种量等因素对发酵产纤维素酶的影响。结合单因素影响实验得到优化后的培养基配方为:羧甲基纤维素钠1.5%,酵母粉1%,NaCl 1%,MgSO_4·7H_2O 2‰,KH_2PO_4·3H_2_O 1‰。优化后的发酵条件为:初始pH为8,接种量1%,种龄8h,培养时间48h。经过发酵工艺优化,S-16产生的羧甲基纤维素酶活(CMCase)和滤纸酶活(FPase)分别达到4.64IU/mL和0.46IU/mL,与初始培养条件下的酶活相比分别提高了3.14倍和1.30倍。本研究得到的枯草芽胞杆菌S-16及其优化发酵工艺为秸秆的快速腐熟和高产纤维素酶的应用奠定了基础。     

β-Lactamase production and in vitro antimicrobial susceptibility of Porphyromonas gingivalis

Abstract β-Lactamase production by 98 Porphyromonas strains was investigated by the nitrocefin (chromogenic cephalosporin) test. Human isolates of P. gingivalis (91), P. endodontalis (2), and P. asaccharolytica (1) were tested, with four closely related Porphyromonas spp. of animal origin and four reference strains. The in vitro susceptibility of 64 P. gingivalis strains was investigated on Brucella blood agar by the E test. None of the human Porphyromonas isolates tested produced β-lactamase, but one Porphyromonas strain of animal origin, most closely resembling P. endodontalis , produced β-lactamase. P. gingivalis was susceptible to almost all of the drugs tested: benzylpenicillin, ampicillin, cefaclor, cefuroxime, erythromycin, clindamycin, tetracycline, doxycycline, metronidazole and ciprofloxacin; all strains were inhibited at 0.016 μg/ml, 0.023 μg/ml, 0.315 μg/ml, 0.064 μg/ml, 0.19 μg/ml, 0.016 μg/ml, 0.094 μg/ml, 0.047 μg/ml, 0.023 μg/ml, and 0.75 μg/ml of these drugs, respectively. Cotrimoxazole exhibited variable efficacy against P. gingivalis ; the range of MICs was 0.1095-32.0 μg/ml. The results indicate that β-lactamase production is currently not a problem amongst clinical isolates of P. gingivalis and strains are susceptible to most antimicrobial agents.     

Biochemical studies on the production of neuraminidase by environmental isolates of Vibrio cholerae non-O1 from Bulgaria

Neuraminidase is a key factor in the infectious process of many viruses and pathogenic bacteria. The neuraminidase enzyme secreted by the etiological agent of cholera?- Vibrio cholerae О1?- is well studied in contrast with the one produced by non-O1/non-O139 V.?cholerae. Environmental non-O1/non-O139 V. cholerae isolates from Bulgaria were screened for production of neuraminidase. The presence of the neuraminidase gene nanH was detected in 18.5% of the strains. Тhe strain showing highest activity (30 U/mL),?V. cholerae non-O1/13, was used to investigate the enzyme production in several media and at different aeration conditions. The highest production of extracellular neuraminidase was observed under microaerophilic conditions, which is possibly related to its role in the infection of intestine epithelium, where the oxygen content is low. On the other hand, this is another advantage of the microbe in such microaerophilic environments as sediments and lake mud. The highest production of intracellular neuraminidase was observed at anaerobic conditions. The ratio of extracellular to intracellular neuraminidase production in V. cholerae was investigated. The temperature optimum of the enzyme was determined to be 50?°C and the pH optimum to be?5.6-5.8.     

Kinetic properties of Helicobacter pylori urease compared with jack bean urease

The urease proteins of the jack bean (Canavalia ensiformis) and Helicobacter pylori are similar in molecular mass when separated by non-denaturing gradient polyacrylamide gel electrophoresis, both having three main forms. The molecular mass of their major protein form is within the range 440-480 kDa with the other two lesser forms at 230-260 kDa and 660-740 kDa. These forms are all urease active; however, significant kinetic differences exist between the H. pylori and jack bean ureases. Jack bean urease has a single pH optimum at 7.4, whereas H. pylori urease has two pH optima of 4.6 and 8.2 in barbitone and phosphate buffers that were capable of spanning the pH range 3 to 10. The H. pylori Km was 0.6 mM at pH 4.6 and 1.0 mM at pH 8.2 in barbitone buffer, greater than 10.0 mM, and 1.1 mM respectively in phosphate buffer and also greater than 10.0 mM in Tris.HCl at pH 8.2. By comparison, the jack bean urease had a Km of 1.3 mM in Tris.HCl under our experimental conditions. The findings show that the urease activity of H. pylori was inhibited at the pH optimum of 4.6 in the phosphate buffer, but not in the barbitone buffer. This was shown to be due to competitive inhibition by the sodium and potassium ions in the phosphate buffer, not the phosphate ions as suggested earlier. Jack bean urease activity was similarly inhibited by phosphate buffer but again due to the effect of sodium and potassium ions.     

Investigation of Helicobacter pylori ascorbic acid oxidating activity

Abstract Helicobacter pylori sonicate was shown to oxidize ascorbic acid. Ascorbic acid oxidation was determined by chromatography combined with electrochemical detection. Water soluble ascorbic acid oxidase activity was rather independent of pH with a pH optimum around 2. By gel filtration the oxidizing activity co-eluted with an absorbency peak at 408 nm. The relative molecular mass ( M _r) was approximately 14000. It is suggested that this oxidating activity was caused by a cytochrome c -like molecule. Ascorbic acid oxidating activity could also be extracted from bacterial membranes by detergents. Gel filtration showed several forms, the major one with a M _r= 19000. pH optimum was 6–7. Other oxidase-positive bacterial strains like Campylobacter coli, Enterobacter cloacae and Pseudomonas aeruginosa could degrade ascorbic acid. Since ascorbic acid oxidation by Helicobacter pylori whole bacterial lysates has a pH optimum in the acidic range corresponding to pH in gastric fluid, the activity of the cytochrome c -like water soluble oxidant of Helicobacter pylori seems to be primarily important for the destruction of ascorbic acid in the gastric juice of infected patients.     

Alkaline-active xylanase produced by an alkaliphilicBacillus sp isolated from kraft pulp

ABacillus sp (V1-4) was isolated from hardwood kraft pulp. It was capable of growing in diluted kraft black liquor at pH 11.5 and produced 49 IU (mol xylose min^–1 ml^–1) of xylanase when cultivated in alkaline medium at pH 9. Maximal enzyme activity was obtained by cultivation in a defined alkaline medium with 2% birchwood xylan and 1% corn steep liquor at pH 9, but high enzyme production was also obtained on wheat bran. The apparent pH optimum of the enzyme varied with the pH used for cultivation and the buffer system employed for enzyme assay. With cultivation at pH 10 and assays performed in glycine buffer, maximal activity was observed at pH 8.5; with phosphate buffer, maximal activity was between pH 6 and 7. The xylanase temperature optimum (at pH 7.0) was 55°C. In the absence of substrate, at pH 9.0, the enzyme was stable at 50°C for at least 30 min. Elecrophoretic analysis of the crude preparation showed one predominant xylanase with an alkaline pl. Biobleaching studies showed that the enzyme would brighten both hardwood and softwood kraft pulp and release chromophores at pH 7 and 9. Because kraft pulps are alkaline, this enzyme could be used for prebleaching with minimal pH adjustment.     

Light inactivation of food-related pathogenic bacteria using a pulsed power source

The effects of high intensity light emissions, produced by a novel pulsed power energization technique (PPET), on the survival of bacterial populations of verocytotoxigenic Escherichia coli (serotype 0157:H7) and Listeria monocytogenes (serotype 4b) were investigated. Using this PPET approach, many megawatts (MW) of peak electrical power were dissipated in the light source in an extremely short energization time (about 1 μs). The light source was subjected to electric field levels greater than could be achieved under conventional continuous operation, which led to a greater production of the shorter bacteriocidal wavelengths of light. In the exposure experiments, pre-determined bacterial populations were spread onto the surface of Trypone Soya Yeast Extract Agar and were then treated to a series of light pulses (spectral range of 200–530 nm) with an exposure time ranging from 1 to 512 μs. While results showed that as few as 64 light pulses of 1 μs duration were required to reduce E. coli 0157:H7 populations by 99·9% and Listeria populations by 99%, the greater the number of light pulses the larger the reduction in cell numbers ( P < 0·01). Cell populations of E. coli 0157:H7 and Listeria were reduced by as much as 6 and 7 log₁₀ orders at the upper exposure level of 512 μs, respectively. Survival data revealed that E. coli 0157:H7 was less resistant to the lethal effects of radiation ( P < 0·01). These studies have shown that pulsed light emissions can significantly reduce populations of E. coli 0157:H7 and L. monocytogenes on exposed surfaces with exposure times which are 4–6 orders of magnitude lower than those required using continuous u.v. light sources.     

Purification and characterization of a β-glucosidase from the phytopathogenic fungus Fusarium oxysporum f. sp. melonis

T.M. ALCONADA AND M.J. MARTÍNEZ. 1996. Fusarium oxysporum f. sp. melonis produces cellulase and β-glucosidase activities in a medium with glucose and avicel as carbon source. A β-glucosidase from this crude material was purified by gel filtration and ion exchange chromatography successively. This enzyme is a unique band of protein in SDS-PAGE and isoelectric focussing. It had a molecular weight of 66000 and a pI of 5. Using p -nitrophenyl-β-D-glucopyranoside as substrate β-glucosidase shows a K _m of 210 μmol 1^-1, an optimum pH of 5.5 and an optimum reaction temperature of 60°C, being stable in a pH range of 5–7 for 48 h at room temperature.     

Comparison of epilithic and epixylic biofilm development in a boreal river

SUMMARY. 1. We assessed substratum effects on lotic biofilm development by placing glass and white pine sampling units in a fourth-order boreal river, and analysing, at 6-week intervals, upper-surface biofilms for ATP, chlorophyll, ergosterol, and the activities of nine exoenzymes.
2. All parameters, except chlorophyll standing stock (range 80–320 μg dm⁻²) and β-xylosidase activity (range 0.4–4.8 μmol h⁻¹ dm⁻²), were significantly greater for epixylic biofilms than for epilithic ones, but the magnitude of the increases varied from 2 to 5 fold, showing that, even under similar hydrodynamic conditions, epilithic and epixylic biofilms are structurally and functionally distinct. For example, ergosterol concentrations ranged from undetectable to 0.93 μg dm⁻² for epilithon and from 11–49 μg dm⁻² for epixylon; corresponding ranges for ATP were 1.6–3.7 (epilithon) and 4.2–7.7 μg dm⁻² (epixylon), for acid phosphatase activity: 2.3–4.9 and 20–41 μmolh⁻¹dm⁻², and for alkaline phosphatase activity: 1.9–8.1 and 29–150 μmol h⁻¹dm⁻², respectively.
3. The more extensive epixylic development was attributed to utilization of the wood substratum as a supplemental carbon source and to a higher density of microbial attachment sites.     

Soluble auxin-binding proteins in pea epicotyls

Auxin-binding proteins, have been identified in the soluble cytoplasrnic protein fraction of etiolated pea epicotyls, Pisum sativum L., cv. "Dippes Gelbe Victoria". The binding is specific for the auxins NAA, IAA and 2,4-D with a K_D in the range of 0.1–0.4 μ M . Moreover, the binding is competitive, sensitive to digestion by proteinase and shows linearity with the protein content of the assay mixture. The binding proteins appear to be very labile, since repeated freezing and thawing destroys specific binding. No clear pH-optimum could be detected in the physiological pH-range 5.5–8.0, but the binding was doubled at pH 8.0 compared to pH 5.5–7.0.     

Prevalence of Primary Fluoroquinolone Resistance Among Clinical Isolates of Helicobacter pylori at a University Hospital in Southern Taiwan

Background:  Fluoroquinolone-containing therapy is effective in eradicating Helicobacter pylori . However, the resistance rate of H. pylori to fluoroquinolones in Taiwan has not yet been reported. In this study, we aimed to investigate the susceptibility to antibiotics commonly used in eradication schedules and fluoroquinolones in H. pylori .
Methods:  A total of 210 clinical isolates of H. pylori were collected from April 1998 to September 2007 from patients in southern Taiwan. The in vitro activities of six antimicrobial agents were determined by the agar dilution method and Etest. The mutations in quinolone resistance-determining regions of gyrA and gyrB were investigated by direct sequencing.
Results:  Overall, 5.7% of the isolates were resistant to ciprofloxacin and levofloxacin. The resistance rate to amoxicillin, clarithromycin, metronidazole, and tetracycline was 1.0% (two of 210), 9.5% (20 of 210), 27.6% (58 of 210), and 0.5% (one of 210), respectively. The resistance rate to either ciprofloxacin or to levofloxacin increased from 2.8% (1998–2003) to 11.8% (2004–2007). The mutations in gyrA at N87 or D91 had an impact on primary fluoroquinolone resistance in H. pylori . Garenoxacin, but not moxifloxacin, had a good in vitro inhibitory effect against ciprofloxacin/levofloxacin-resistant strains compared with objective minimal inhibitory concentration values.
Conclusions:  Drug resistance to ciprofloxacin and levofloxacin in H. pylori collected from 2004 to 2007 increased significantly compared with resistance level observed during 1998–2003. The continuous surveillance of quinolone resistance among H. pylori is important in this area.