Suppression of leaf feeding and oviposition of phytophagous ladybird beetles (Coleoptera: Coccinellidae) by chitinase gene-transformed phylloplane bacteria and their specific bacteriophages entrapped in alginate gel beads

The chitinase gene-transformed strain KPM-007E/chi of Enterobacter cloacae was vitally entrapped in sodium alginate gel beads with its specific virulent bacteriophage EcP-01 to provide a new method for microbially digesting chitinous peritrophic membranes of phytophagous ladybird beetles Epilachna vigintioctopunctata. First, chitinase SH1 from a gram-positive bacterium Kurthia zopfii was overproduced by Escherichia coli cells and purified by affinity column chromatography. The purified enzyme effectively digested peritrophic membranes dissected from the ladybird beetles to expose epithelial tissues beneath the peritrophic membrane, and the beetles that had ingested chitinase after submergence in chitinase solution had considerably reduced their feeding on tomato leaves. KPM-007E/chi, entrapped in the alginate beads, released the chitinase. More chitinase was released when KPM-007E/chi was present with their specific virulent bacteriophage EcP-01 in the beads because of lysis of bacterial cells infected with the bacteriophages. This chitinase release from the microbial beads (containing KPM-007E/chi and EcP-01) was sufficient to digest the peritrophic membrane as well as to suppress feeding of bead-sprayed tomato leaves by the ladybird beetles. A daily supply of tomato leaves treated with the microbial beads considerably suppressed leaf feeding and oviposition by the ladybird beetles, suggesting a possible application of chitinase-secreting bacteria for suppressing herbivorous insect pests.     

Prevalence of the stx2 gene in coliform populations from aquatic environments

Shiga toxin-producing Escherichia coli strains are human pathogens linked to hemorrhagic colitis and hemolytic uremic syndrome. The major virulence factors of these strains are Shiga toxins Stx1 and Stx2. The majority of the genes coding for these toxins are borne by bacteriophages. Free Stx2-encoding bacteriophages have been found in aquatic environments, but there is limited information about the lysogenic strains and bacteria present in the environment that are susceptible to phage infection. The aim of this work was to study the prevalence and the distribution of the stx(2) gene in coliform bacteria in sewage samples of different origins. The presence of the stx(2) gene was monitored every 2 weeks over a 1-year period in a municipal sewage treatment plant. A mean value of 10(2) genes/ml was observed without significant variation during the study period. This concentration was of the same order of magnitude in raw municipal sewage of various origins and in animal wastewater from several slaughterhouses. A total of 138 strains carrying the stx(2) gene were isolated by colony hybridization. This procedure detected approximately 1 gene-carrying colony per 1,000 fecal coliform colonies in municipal sewage and around 1 gene-carrying colony per 100 fecal coliform colonies in animal wastewaters. Most of the isolates belonged to E. coli serotypes other than E. coli O157, suggesting a low prevalence of strains of this serotype carrying the stx(2) gene in the wastewater studied.     

Prevalence of the stx2 Gene in Coliform Populations from Aquatic Environments

Shiga toxin-producing Escherichia coli strains are human pathogens linked to hemorrhagic colitis and hemolytic uremic syndrome. The major virulence factors of these strains are Shiga toxins Stx1 and Stx2. The majority of the genes coding for these toxins are borne by bacteriophages. Free Stx2-encoding bacteriophages have been found in aquatic environments, but there is limited information about the lysogenic strains and bacteria present in the environment that are susceptible to phage infection. The aim of this work was to study the prevalence and the distribution of the stx₂ gene in coliform bacteria in sewage samples of different origins. The presence of the stx₂ gene was monitored every 2 weeks over a 1-year period in a municipal sewage treatment plant. A mean value of 10² genes/ml was observed without significant variation during the study period. This concentration was of the same order of magnitude in raw municipal sewage of various origins and in animal wastewater from several slaughterhouses. A total of 138 strains carrying the stx₂ gene were isolated by colony hybridization. This procedure detected approximately 1 gene-carrying colony per 1,000 fecal coliform colonies in municipal sewage and around 1 gene-carrying colony per 100 fecal coliform colonies in animal wastewaters. Most of the isolates belonged to E. coli serotypes other than E. coli O157, suggesting a low prevalence of strains of this serotype carrying the stx₂ gene in the wastewater studied.     

Development of a 23S rRNA-based PCR assay for the identification of Pasteurella multocida

AIMS: The aim of this work was to develop a rapid diagnostic test for Pasteurella multocida. METHODS AND RESULTS: A polymerase chain reaction (PCR) assay using primers derived from the 23S rRNA gene sequence of Past. multocida was developed. The PCR assay correctly identified all 144 isolates of Past. multocida tested, including type strains of the three subspecies as well as the reference strains for the Heddleston and Carter typing schemes. Of 20 closely related bacteria from the family Pasteurellaceae tested, only the type strains of Past. canis biovar 2 and Past. avium biovar 2 were positive. These two bacteria, formerly known as Bisgaard Taxon 13, are the closest phylogenetic relatives of Past. multocida based on 16S ribosomal rRNA. All phylogenetically unrelated avian and porcine organisms tested were negative. CONCLUSION: This PCR enables rapid identification of Past. multocida colonies from avian or porcine origin. SIGNIFICANCE AND IMPACT OF THE STUDY: Veterinary diagnostic laboratories can use this PCR to rapidly and accurately diagnose fowl cholera and porcine pasteurellosis.     

Phage-Encoded Colanic Acid-Degrading Enzyme Permits Lytic Phage Infection of a Capsule-Forming Resistant Mutant Escherichia coli Strain

In this study, we isolated a bacteriophage T7-resistant mutant strain of Escherichia coli (named S3) and then proceeded to characterize it. The mutant bacterial colonies appeared to be mucoid. Microarray analysis revealed that genes related to colanic acid production were upregulated in the mutant. Increases in colanic acid production by the mutant bacteria were observed when l-fucose was measured biochemically, and protective capsule formation was observed under an electron microscope. We found a point mutation in the lon gene promoter in S3, the mutant bacterium. Overproduction of colanic acid was observed in some phage-resistant mutant bacteria after infection with other bacteriophages, T4 and lambda. Colanic acid overproduction was also observed in clinical isolates of E. coli upon phage infection. The overproduction of colanic acid resulted in the inhibition of bacteriophage adsorption to the host. Biofilm formation initially decreased shortly after infection but eventually increased after 48 h of incubation due to the emergence of the mutant bacteria. Bacteriophage PBECO4 was shown to infect the colanic acid-overproducing mutant strains of E. coli. We confirmed that the gene product of open reading frame 547 (ORF547) of PBECO4 harbored colanic acid-degrading enzymatic (CAE) activity. Treatment of the T7-resistant bacteria with both T7 and PBECO4 or its purified enzyme (CAE) led to successful T7 infection. Biofilm formation decreased with the mixed infection, too. This procedure, using a phage cocktail different from those exploiting solely receptor differences, represents a novel strategy for overcoming phage resistance in mutant bacteria.     

The novel method for isolating chitinolytic bacteria and its application in screening for hyperchitinase producing mutant of Alcaligenes xylosoxydans

AIMS: To develop a novel, rapid and effective screening method for chitinase producing bacteria. METHODS AND RESULTS: A simple and rapid technique for screening of potential chitinolytic bacteria has been developed using the chitin binding dye calcofluor white M2R in chitin agar. Microorganisms possessing high chitinolytic potential gave a clear zone under ultraviolet light after 24-48 h of incubation. This method was successfully applied for isolating the hyperchitinase mutant of Alcaligenes xylosoxydans. The mutant Alc. xylosoxydans EMS 33 was found to produce 3.4 times more chitinase than the wild type. CONCLUSIONS: In this study, the screening method for chitinase producing bacteria has been developed and it was applied to screen chitinase-overproducing mutant of Alc. xylosoxydans. SIGNIFICANCE AND IMPACT OF THE STUDY: The novel screening method for chitinase producer is more sensitive, rapid, user-friendly and reliable, which can also be used for screening of recombinants having chitinase gene.     

Characterization of Lactococcus garvieae isolated from radish and broccoli sprouts that exhibited a KG+ phenotype, lack of virulence and absence of a capsule

AIMS: To identify Lactococcus garvieae isolates from radish and broccoli sprouts and compare them with virulent and less virulent mutant strains obtained from yellowtails with regard to KG phenotype, presence of a capsule and virulence towards yellowtails and mice. METHODS AND RESULTS: Comparative 16S rRNA gene sequence analysis of six isolates obtained from radish and broccoli sprouts indicated that they were L. garvieae (similarity >99%). They were compared with KG9502, Lg2 and ATCC49156 strains obtained from yellowtails. A less virulent mutant strain Lg2-S was obtained by Lg2 subculture. Biochemical characterization of the six strains resembled that of KG9502, Lg2, ATCC49156 and Lg2-S, except for saccharose and tagatose acidification and the presence of hippuricase. These six strains were nonpathogenic towards yellowtails and mice, nonsusceptible to bacteriophages and demonstrated heterogeneity on pulsed-field gel electrophoresis analysis. Using transmission electron microscopy, a capsule was observed in KG9502 and Lg2 but not in ATCC49156 and Lg2-S. CONCLUSIONS: We isolated L. garvieae strains that lacked pathogenicity towards yellowtails and mice from radish and broccoli sprouts; these were noncapsulated and exhibited KG(+) phenotype. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first documentation of L. garvieae isolated from terrestrial plants. These isolates exhibited genetic diversity; however, they were noncapsulated and nonpathogenic towards yellowtails and mice.     

Transgenic ice nucleation-active Enterobacter cloacae reduces cold hardiness of corn borer and cotton bollworm larvae

The ice nucleation (IN) gene iceA of Erwinia ananas 110 was integrated into the chromosomes of two Enterobacter cloacae strains (Enc1.2022 and Enc1.181). These two newly derived transgenic strains, designated Enc2022-I and Enc181-I, respectively, possessed ice nucleation activity at -2.5 degrees C, significantly higher than their parent strains (active at approx -10 degrees C or lower). After ingesting these transgenic bacteria, the mean supercooling points (SCPs) of corn borer and cotton bollworm larvae were -3 to -4 degrees C, significantly higher than those of untreated controls. The SCPs remained significantly elevated over the 9-day period after ingestion, which matched well with the efficient gut colonization of the bacteria during this period. All treated larvae froze and eventually died after exposure for 6 h to a temperature of -7 degrees C, and more than 95% died after 12 h at -5 degrees C. In contrast, few or none of the untreated control larvae froze and died under the same conditions. Furthermore, the growth ability of these transgenic ice nucleation-active (INA) En. cloacae strains on corn leaves was reduced, compared to that of wild-type epiphytic E. ananas, as revealed by pot tests conducted in both greenhouse and outdoor conditions. The stable colonization in insect guts and their lower affinity to plants would make these transgenic INA bacteria useful as a novel tool for biological control of insect pests in agricultural fields.     

Characterization of a virulent bacteriophage specific for Escherichia coli O157:H7 and analysis of its cellular receptor and two tail fiber genes

A virulent phage, named PP01, specific for Escherichia coli O157:H7 was isolated from swine stool sample. The phage concentration in a swine stool, estimated by plaque assay on E. coli O157:H7 EDL933, was 4.2x10(7) plaque-forming units per g sample. PP01 infects strains of E. coli O157:H7 but does not infect E. coli strains of other O-serogroups and K-12 strains. Infection of an E. coli O157:H7 culture with PP01 at a multiplicity of infection of two produced a drastic decrease of the optical density at 600 nm due to cell lysis. The further incubation of the culture for 7 h produced phage-resistant E. coli O157:H7 mutant. One PP01-resistant E. coli O157:H7 mutant had lost the major outer membrane protein OmpC. Complementation by ompC from a O157:H7 strain but not from a K-12 strain resulted in the restoration of PP01 susceptibility suggesting that the OmpC protein serves as the PP01 receptor. DNA sequences and homology analysis of two tail fiber genes, 37 and 38, responsible for the host cell recognition revealed that PP01 is a member of the T-even bacteriophages, especially the T2 family.     

Efficient release of overproduced gene products from Escherichia coli BL21(DE3) by lytic infection with newly isolated bacteriophages

Overproduced proteins from Escherichia coli BL21(DE3) were efficiently released with virulent bacteriophages. Leviviridae-like bacteriophages were isolated from soil and used to lyse BL21(DE3) cells transformed with beta-glucosidase, chitinase, or chitosanase genes. This method caused lysis of bacterial cells similar to that by conventional sonication and enabled us to effectively recover and purify the enzymes.     

prbA,a gene coding for an esterase hydrolyzing parabens in enterobacter cloacae and Enterobacter gergoviae strains

The new gene prbA encodes an esterase responsible for the hydrolysis of the ester bond of parabens in Enterobacter cloacae strain EM. This gene is located on the chromosome of strain EM and was cloned by several PCR approaches. The prbA gene codes for an immature protein of 533 amino acids, the first 31 of which represent a proposed signal peptide yielding a mature protein of a putative molecular mass of 54.6 kDa. This enzyme presents analogies with other type B carboxylesterases, mainly of eukaryotic origin. The cloning and expression of the prbA gene in a strain of Escherichia coli previously unable to hydrolyze parabens resulted in the acquisition of a hydrolytic capacity comparable to the original activity of strain EM, along with an increased resistance of the transformed strain to methyl paraben. The presence of homologues of prbA was tested in additional ubiquitous bacteria, which may be causative factors in opportunistic infections, including Enterobacter gergoviae, Enterobacter aerogenes, Pseudomonas agglomerans, E. coli, Pseudomonas aeruginosa, and Burkholderia cepacia. Among the 41 total strains tested, 2 strains of E. gergoviae and 1 strain of Burkholderia cepacia were able to degrade almost completely 800 mg of methyl paraben liter(-1). Two strains of E. gergoviae, named G1 and G12, contained a gene that showed high homology to the prbA gene of E. cloacae and demonstrated comparable paraben esterase activities. The significant geographical distance between the locations of the isolated E. cloacae and E. gergoviae strains suggests the possibility of an efficient transfer mechanism of the prbA gene, conferring additional resistance to parabens in ubiquitous bacteria that represent a common source of opportunistic infections.     

湖北地区部分医院肠球菌耐药性监测及相关因素分析

目的：了解湖北地区2000年度肠球菌的分离情况及耐药状况,并对抗感染用药进行探索,指导临床合理用药。方法：对湖北地区15所三甲医院各类临床标本中的538株肠球菌采用API细菌鉴定系统或Vitek全自动细菌鉴定系统进行分离鉴定,用纸片扩散法进行药敏试验,并以WHO细菌耐药监测网提供的WHONET4软件分析系统对试验数据进行分析处理。结果：本试验共分离肠球菌13个种别538株,其中大多数是粪肠球菌408株,占75.8%,屎肠球菌54株,占10.0%;坚忍肠球菌24株,占4.46%;鸟肠球菌10株,占1.86%。酪黄肠球菌6株,占1.11%;母鸡肠球菌6株,占1.11%等。本研究结果表明肠球菌的主要感染部位为泌尿道31.4%和各种分泌物31.0%。同时从药敏结果可见屎肠球菌和坚忍肠球菌对大多数抗生素的耐药性高于粪肠球基本国策 ;并发现糖肽类抗生素耐药菌株比例尚不高;庆大霉素呈高水平耐药球菌株比例则较高;对青霉素和氨卞西林耐药,本研究结果亦有反映,并且鸟肠球菌的耐药性高于粪肠球菌近三倍。结论：本年度分离的肠球菌占全年总分离菌的第六位,说明我国目前由肠球菌引起的感染所占比例不高,但仍应引起临床的高度重视,并进行动态的监测。加强对肠球菌特别是VRR耐药性的监测是非常必要的,泌尿道肠球菌感染的抗生素中呋喃妥因的耐药率较四环素和喹诺酮类药物为低,故仍不失为治疗该类泌感的首选药物,菌株差别与地区有关,由于肠球菌属中的不同种对抗生素的敏感性不同。因此种的鉴定是对该地区医院感染暴发流行,选择治疗方案的重要工具。     

Expression of AmpC beta-lactamase in Enterobacter cloacae isolated from retail ground beef, cattle farm and processing facilities

AIMS: To better understand antibiotic resistance of Enterobacter cloacae isolates originated from food animals, the phenotypic and genotypic resistance of Ent. cloacae isolates from retail ground beef, cattle farm, processing facilities and clinical settings were investigated. METHODS AND RESULTS: The ampC, ampD and ampR genes in the isolates were sequenced and analysed. beta-Lactamase activities and beta-lactamase profiles of the isolates were analysed by the enzymatic hydrolysis of nitrocefin and isoelectric focussing, respectively. The ampC gene of the Ent. cloacae isolate was cloned and transformed into Escherichia coli strains. The genomic DNA profiles of Ent. cloacae isolates were analysed by using pulse field gel electrophoresis (PFGE). Mutation at one residue (Val-54-->Ile) in the AmpR amino acid sequence was consistently found in Ent. cloacae isolates that were resistant to a broadspectrum of beta-lactam agents. The enzyme activity in the isolates was induced by cefoxitin. The pI (isoelectric point) of the enzymes produced by the test strains ranged from 8.4 to 8.9. Cloning of ampC gene of the Ent. cloacae isolate conferred the resistance to ampicillin, cephalothin and amoxicillin in recipient E. coli strains. One recipient of E. coli O157:H7 strain additionally acquired resistance to ceftiofur. The genomic analysis of Ent. cloacae isolates by PFGE showed that the isolates from various sources were genetically unrelated. CONCLUSIONS: The spread of diverse clones of AmpC-producing Ent. cloacae occurred in the ecosystem and retail products. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings suggested that AmpC-producing Ent. cloacae could be a contributor in spreading beta-lactamase genes in farm environments and food processing environments.     

Classification of 17 newly isolated virulent bacteriophages of Pseudomonas aeruginosa

Seventeen virulent bacteriophages specific to Pseudomonas aeruginosa strains were isolated by screening various environmental samples. These isolated bacteriophages were grouped based on results obtained from restriction fragment analysis of phage genomes, random amplification of polymorphic DNA (RAPD) typing, morphology observations under transmission electron microscope, and host range analysis. All 17 bacteriophages are double-stranded DNA viruses and can be divided into 5 groups based on DNA restriction profiles. A set of 10-mer primers was used in RAPD typing of phages, and similar conclusions were obtained as for restriction fragment analysis. One phage was randomly selected from each of the 5 groups for morphology observations. Four of them had an icosahedral head with a long contractile tail, belonging to the Myoviridae family, and one phage had an icosahedral head with a short tail, thereby belonging to the Podoviridae family. Host range experiments were conducted on 7 laboratory strains and 12 clinical strains of P.?aeruginosa. The results showed that 13 phages had the same infection profile, killing 8 out of 19 tested P.?aeruginosa strains, and the remaining 4 phages had different and unique infection profiles. This study highlights the diversity of bacteriophages specific to P.?aeruginosa in the environment.     

Investigation of the cytotoxic capacity of some adherent opportunistic enterobacterial strains by the MTT assay and transmission electron microscopy

The purpose of this study was to determine the cytotoxic effect on CaCo-2 intestinal cells of dialysates obtained from bacterial cultures of some enterobacterial opportunistic strains with different sources of isolation (food, stool culture, acute diarrhoea, urine culture), previously tested and selected for their intensive adherence and invasion capacity to the cellular substratum and also for their cytotoxic effect on cell monolayers. In this study the level of cytotoxicity was measured quantitatively by means of the MTT assay and qualitatively by transmission electron microscopy (TEM). The MTT method uses a tetrazolium salt for the quantitative spectrophotometric assay of CaCo-2 cells survival and proliferation rates in the presence of bacterial dialysates. This test detects the viable cells, which are able to reduce the tetrazolium salt and offers the advantages of a very simple, rapid and precise method. For TEM examination the ultrathin sections were prepared following the standard protocols. The most cytotoxic strains proved to be Citrobacter freundii 93 strain isolated from stool culture, and Enterobacter cloacae 43, isolated from food followed by E. coli 115 strain isolated from acute diarrhoea. These results correlate well with TEM results pointing out the cytotoxic effect of Enterobacter cloacae 43 strain and also its ability to induce attachment and to destroy the cell surface (A/E) of HEp-2 cells. Besides their great adherence and invasion capacity, the production and release of cytotoxic factors into the extracellular medium represent virulence factors in these strains. This could be responsible for the increase of the pathogenic potential of opportunistic bacteria and explain their implication in the etiology of severe infections and food-borne diseases. This study proved that the virulence of opportunistic pathogens is not correlated with the strain's origin, the most evident virulence features being exhibited by an Enterobacter cloacae strain isolated from food.     

Identification of important amino acid residues that modulate binding of Escherichia coli GroEL to its various cochaperones

Genetic experiments have shown that the GroEL/GroES chaperone machine of Escherichia coli is absolutely essential, not only for bacterial growth but also for the propagation of many bacteriophages including lambda. The virulent bacteriophages T4 and RB49 are independent of the host GroES function, because they encode their own cochaperone proteins, Gp31 and CocO, respectively. E. coli groEL44 mutant bacteria do not form colonies above 42 degrees nor do they propagate bacteriophages lambda, T4, or RB49. We found that the vast majority (40/46) of spontaneous groEL44 temperature-resistant colonies at 43 degrees were due to the presence of an intragenic suppressor mutation. These suppressors define 21 different amino acid substitutions in GroEL, each affecting one of 13 different amino acid residues. All of these amino acid residues are located at or near the hinge, which regulates the large en bloc movements of the GroEL apical domain. All of these intragenic suppressors support bacteriophages lambda, T4, and RB49 growth to various extents in the presence of the groEL44 allele. Since it is known that the GroEL44 mutant protein does not interact effectively with Gp31, the suppressor mutations should enhance cochaperone binding. Analogous intragenic suppressor studies were conducted with the groEL673 temperature-sensitive allele.     

Escherichia coli with anti-O157:H7 activity isolated from bovine colon

AIMS: To isolate bacteria from bovine gastrointestinal tract and investigate their inhibitory effect on Escherichia coli O157:H7 in vitro. METHODS AND RESULTS: A total of 2400 bacterial colonies were isolated from cattle colonic mucous membrane. Thirteen strains demonstrated the ability to inhibit the growth of E. coli O157:H7. From these, seven were screened for the presence of virulence factors as: stx(1), stx(2), ehxA, eae, st1a and lt1 by polymerase chain reaction. The selected bacteriocin-producing bacteria showed susceptibility to most of the antibiotics used. CONCLUSIONS: The strains of E. coli isolated, which exhibit inhibitory activity on E. coli O157:H7 growth by the production of inhibitory substances, may be useful in the control of this pathogen in reservoirs. An important characteristic of these strains was the absence of any of the virulence factors assayed and the susceptibility to most of the antibiotics used for Gram-negative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: These microorganisms might be used as probiotic bacteria to reduce the carriage of E. coli O157:H7 in cattle, thus limiting the contamination of carcasses at slaughter and subsequently the contamination of foods and the transfer of this pathogen to man.     

Role of horizontal gene transfer by bacteriophages in the origin of pathogenic bacteria

The review considers the involvement of bacteriophages in transferring genes, which determine bacterial pathogenicity, and the increasing role of comparative genomics and genetics of bacteria and bacteriophages in detecting new cases of horizontal gene transfer. Examples of phage participation in this process proved to a different extent are described. Emphasis is placed on the original work carried out in Russia and focused on bacteriophages (temperate transposable phages and giant virulent phi KZ-like phages) of conditional pathogen Pseudomonas aeruginosa. Consideration is given to the possible lines of further research of the role of bacteriophages in the infection process and, in particular, the role of virulent phages, whose products are similar to those of pathogenic bacteria, in modification of clinical signs of infectious diseases and in evolution. An attempt is made to predict the possible direction of pathogen evolution associated with development of new treatment strategies and generation of new specific niches.     

Isolation and characterization of bacteriophages for avian pathogenic E. coli strains

Aims:  To isolate and characterize bacteriophages, and to evaluate its lytic performance against avian pathogenic Escherichia coli (APEC) strains with high patterns of antibiotic resistance, in order to select phages for a therapeutic product to treat colibacillosis in chickens.
Methods and Results:  Bacteriophages were isolated from poultry sewage and tested against 148 O-serotyped APEC strains. The morphological characterization of the bacteriophages was made by transmission electronic microscopy (TEM) observations and the genetic comparison between bacteriophages DNA was performed by restriction fragment length polymorphism (RFLP) patterns. Results showed that 70·5% of the tested E. coli strains were sensitive to a combination of three of the five isolated phages, that seemed to be virulent and taxonomically belong to the Caudovirales order. Two of them look like 16–19, T4-like phages ( Myoviridae ) and the third is a T1-like phage and belongs to Syphoviridae family. All of them are genetically different.
Conclusions:  It was possible to obtain a combination of three different lytic bacteriophages with broad lytic spectra against the most prevalent O-serotypes of APEC.
Significance and Impact of the Study:  Data reported in this study, presents an in vitro well studied phage product to be used as antimicrobial agent to treat colibacillosis in poultry industry.     

肠杆菌科细菌肺部感染病原菌分布与耐药性监测

目的了解浙江龙游县人民医院肠杆菌科细菌肺部感染病原菌分布及耐药性,为临床合理使用抗菌药物提供依据。方法采用纸片扩散法对病原菌进行药敏试验,并进行ESBLs检测,按CLSI 2012年标准判定药敏结果,用WHONET 5.6软件分析结果。结果痰培养共分离出371株肠杆科细菌,主要为肺炎克雷伯菌、大肠埃希菌和阴沟肠杆菌,产ESBLs菌阳性率高,对碳青霉烯类抗菌药物耐药率低,均在10.00%以下,其他药物均有不同程度耐药,测试抗菌药物的耐药率差异有统计学意义（P〈0.05）。结论临床常见肠杆菌科细菌耐药率高,开展病原菌耐药性监测,对指导临床抗感染治疗合理选择抗菌药物具有重要意义。