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PubMed2006

Transformation of Anaplasma phagocytophilum.

BACKGROUND: Tick-borne pathogens cause emerging zoonoses, and include fastidious organisms such as Anaplasma phagocytophilum. Because of their obligate intracellular nature, methods for mutagenesis and transformation have not been available. RESULTS: To facilitate genetic manipulation, we transformed A. phagocytophilum (Ap) to express a green fluorescent protein (GFP) with the Himar1 transposase system and selection with the clinically irrelevant antibiotic spectinomycin. CONCLUSION: These transformed bacteria (GFP/Ap) grow at normal rates and are brightly fluorescent in human, monkey, and tick cell culture. Molecular characterization of the GFP/Ap genomic DNA confirmed transposition and the flanking genomic insertion locations were sequenced. Three mice inoculated with GFP/Ap by intraperitoneal injection became infected as demonstrated by the appearance of morulae in a peripheral blood neutrophil and re-isolation of the bacteria in culture.

Anaplasma phagocytophilum↗
PubMed2006

Antimicrobial and toxicological evaluation of the leaves of Baissea axillaries Hua used in the management of HIV/AIDS patients.

BACKGROUND: Persistent diarrhea is a common endemic disease with high incidence among the Africans including Nigerians. It also represents a frequent opportunistic disease in people living with HIV. Diarrhea represents one of the most distressful and persistent symptoms of HIV/AIDS, which may or may not be accompanied by an infection. The leaves decoction of Baissea axillaries Hua (Apocynaceae) is used by traditional herbalists in Edo state, Nigeria for the management of people living with HIV/AIDS. Determination of its antimicrobial activity and toxicological profile will provide supportive scientific evidence in favour of its continuous usage. METHOD: Chemical and chromatographic tests were employed in phytochemical investigations. Inhibitory activities of aqueous and ethanolic extracts against clinical strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus faecalis were compared with Togamycin (Spectinomycin). Our report includes minimum inhibitory concentration (MIC) against the test organisms. Toxicological evaluation was determined by administering 250 mg/kg and 500 mg/kg of extracts on male Wister rats for 14 days with normal saline as control. The kidneys, liver, heart and testis tissues were examined. RESULTS: Phytochemical studies revealed the presence of alkaloids, tannins, and cyanogenetic glycosides. The extracts inhibited the growth of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus to varying extents, but only the ethanolic extract inhibited growth in Streptococcus faecalis. The LD50 of the extract in mice was above 5000 mg/kg body weight when administered intraperitoneally. Toxicological evaluation showed mere ballooning degeneration of the liver at 250 mg/kg while at 500 mg/kg there was tissue necrosis. The low and high doses showed ill-defined leydig cells in the testis and no remarkable changes in the heart and kidneys. CONCLUSION: Extracts of Baissea axillaries have demonstrated antimicrobial activity against clinical strains of selected microorganisms. While there is toxicity at the dose of 500 mg/kg, the therapy shows potential for application in the treatment of diarrhoea associated with AIDS/HIV. Further studies of Baissea axillaries on diarrhoea and toxicity are necessary to evaluate its mechanism of action and to fully establish its safety profile.

Animals↗
PubMed1997

Evaluation of the standardized disk diffusion and agar dilution antibiotic susceptibility test methods by using strains of Neisseria gonorrhoeae from Tucumán, Argentina.

At present, most Neisseria gonorrhoeae testing is done with beta-lactamase and agar dilution tests using common therapeutic agents. Generally, in bacteriological diagnosis laboratories in Argentina, study of antibiotic susceptibility of N. gonorrhoeae is based on beta-lactamase determination and agar dilution method using common therapeutic agents. The National Committee for Clinical Laboratory Standards (NCCLS) recently described a disk diffusion test that produces results similar to the reference agar dilution method for antibiotic susceptibility of N. gonorrhoeae. We obtained 57 gonococcal isolates from patients attending a clinic for sexually transmitted diseases in Tucumán, Argentina. Antibiotic susceptibility tests using agar dilution and disk diffusion techniques were compared. The established NCCLS interpretive criteria for both susceptibility methods appeared to be applicable to domestic gonococcal strains. The correlation between the minimum inhibitory concentration (MIC's) and the zones of inhibition was studied for penicillin, ampicillin, cefoxitin, spectinomycin, cefotaxime, cephaloridine, cephalexin, tetracycline, norfloxacin and kanamycin. Dispersion diagrams showed a high correlation between both methods, with a sensitivity of 89% and specificity of 91%.

Argentina↗
PubMed1995

Antibiotic treatment of nude rats and its impact on the aerobic bacterial flora.

A colony of nude rats were treated with the antibiotics ampicillin, spiramycin, sulfadoxine/trimethoprim, tetracycline, lincomycin and spectinomycin over a period of 30 weeks. The rats were monitored bacteriologically during the whole treatment period and for a period of 24 weeks after the treatment. Antibiograms of each isolated microorganism were made in vitro. The primary target, Pasteurella pneumotropica, was suppressed by the treatment, but reappeared after ending the medication. Klebsiella pneumoniae subsp. pneumoniae, never observed before the use of antibiotics in the colony, became one of the most common organisms in the colony. Furthermore, this bacterium was resistant to all antibiotics tested in vitro. Also other Enterobacteriaceae and some Streptococcaceae were propagated. Only Staphylococcus aureus seemed to have been eradicated by the treatment. It is concluded, that such antibiotic treatment does not necessarily improve the microbiological quality of the rats, and that it imposes a high risk of propagating resistant bacteria.

Animals↗
PubMed2001

Antimicrobial susceptibilities and plasmid patterns of Neisseria gonorrhoeae in Bénin.

This study describes antimicrobial susceptibility patterns of Neisseria gonorrhoeae isolates obtained from female sex workers in Cotonou, Bénin. All isolates were susceptible to spectinomycin, ceftriaxone and ciprofloxacin, and susceptible to moderately susceptible to kanamycin; 9.8% of isolates were resistant to thiamphenicol; 9%, 87.5% and 3.5% were susceptible, moderately susceptible, resistant to trimethoprim-sulfamethoxazole, respectively; 94.4% and 99.3% were resistant to penicillin and tetracycline, respectively. All isolates with a minimal inhibitory concentration of tetracycline of >8 mg/l carried the 'American type' tetM plasmid; 94% and 6% of penicillinase-producing isolates possessed a 3.2 MDa and a 4.4MDa beta-lactamase plasmid, respectively. Surveillance of antimicrobial susceptibility of N. gonorrhoeae isolates to currently used drugs in Africa should become part of sexually transmitted diseases (STDs) control programmes.

Anti-Bacterial Agents↗
PubMed2002

One year of Neisseria gonorrhoeae isolates in Sweden: the prevalence study of antibiotic susceptibility shows relation to the geographic area of exposure.

The aim of this study was to compare epidemiological data with antibiotic susceptibility patterns, so as to characterize the risk of infection with a highly resistant Neisseria gonorrhoeae strain. N. gonorrhoeae strains isolated in Sweden from February 1998 through January 1999 were tested for antibiotic susceptibility. Epidemiological data were received from each clinician reporting a case of gonorrhoea and these data were linked to the N. gonorrhoeae strains. A total of 348 N. gonorrhoeae isolates, representing 89% of all Swedish cases diagnosed during the 12-month period, were tested for antibiotic susceptibility. Of all isolates, 24% were beta-lactamase-producing, and 18% had decreased susceptibility to ciprofloxacin (MIC>0.064 mg/l). All isolates were fully susceptible to ceftriaxone and spectinomycin. More than 99% of the isolates were fully susceptible to azithromycin. The antibiotic susceptibility varied with the places where patients were exposed to infection. When exposed in Asia, 63% of the isolates showed reduced susceptibility to ciprofloxacin, compared with 0-8.5% of the isolates from patients exposed in other places (RR=8.5, P<0.001). Ciprofloxacin cannot be recommended as the first choice of treatment if the place of exposure was in Asia.

Anti-Bacterial Agents↗
PubMed2002

Laboratory diagnosis of sexually transmitted infections in women with genital discharge in Madagascar: implications for primary care.

Women seeking care in Madagascar for genital discharge (n = 1,066) were evaluated for syphilis seroreactivity; bacterial vaginosis (BV) and trichomoniasis. Chlamydial infection was assessed by ligase chain reaction (LCR) and by direct immunofluorescence (IF); gonorrhoea by direct microscopy, culture and LCR. Leucocytes were determined in endocervical smears and in urine using leucocyte esterase dipstick (LED). Gonococcal isolates were tested for minimal inhibitory concentrations. BV was found in 56%, trichomoniasis in 25%, and syphilis in 6% of the women. LCR detected gonorrhoea in 13% and chlamydial infection in 11% of the women. Detection of Gram(-) intracellular diplococci in endocervical smears, and gonococcal culture were respectively 23% and 57% sensitive and 98% and 100% specific compared to LCR. Chlamydia antigen detection by IF was 75% sensitive and 77% specific compared to LCR. Leucocytes in endocervical smears and LED testing lacked precision to detect gonococcal and chlamydial infections. Of 67 gonococcal strains evaluated, 19% were fully susceptible to penicillin, 33% to tetracycline; all were susceptible to ciprofloxacin, ceftriaxone, and spectinomycin. Patients who present with genital discharge in Madagascar should be treated syndromically for gonococcal and chlamydial infections and screened for syphilis. Gonorrhoea should be treated with ciprofloxacin.

Animals↗
PubMed1998

The availability and cost of antibiotics for treating PID in the Central Region of Ghana and implications for compliance with national treatment guidelines.

The availability and cost of antibiotics for treating pelvic inflammatory disease (PID) were assessed in 17 drug-dispensing outlets in 5 districts of the Central Region, Ghana. The outlets included the dispensaries of 2 regional and 4 district hospitals, 4 privately-owned pharmacies and 7 chemical seller shops. The most common antibiotics available, including co-trimoxazole, metronidazole, benzylpenicillin, amoxycillin, chloramphenicol and gentamicin, were also the lowest-priced drugs. Conversely, the most expensive antibiotics including ceftriaxone, ciprofloxacin, cefuroxime and spectinomycin, were also the least commonly available. Recommended anti-gonococcal antibiotics (ciprofloxacin, ceftriaxone) may not be prescribed if they are not available in the districts.

Anti-Bacterial Agents↗
PubMed1999

Characterization of an outbreak of tetM-containing Neisseria gonorrhoeae in Argentina.

Phenotypic and molecular characterization of an outbreak of 9 Neisseria gonorrhoeae (NG) isolates exhibiting high-level plasmid mediated resistance to penicillin and tetracycline (PP-TRNG) that took place in Tandil, Argentina between February and April 1995. Comparison with the patterns of the 3 PP-TRNG strains previously isolated were made. We determined the following markers for each strain: antimicrobial susceptibility, serogroup, auxotype, plasmid profile, presence of tetM determinant and restriction pattern of the tetM-containing plasmid. Antimicrobial tests values were: tetracycline disk diameter 12-14 mm, minimum inhibitory concentration (MIC) 32 micrograms/ml; penicillin disk diameter 6 mm, MIC 32 micrograms/ml and sensitive by both methods to spectinomycin, cefuroxime, ceftriaxone and ciprofloxacin. All isolates were of the same serogroup (WI). Ten of the strains, including the 9 from Tandil outbreak, were arginine-requiring, while the other 2 were methionine and arginine-requiring. All of them demonstrate the same plasmid profile (2.6, 3.2, 25.2 MDa). They were positive for the tetM determinant and the restriction analysis identified it is a Dutch-type plasmid. In spite of the temporal and geographical dispersion, PP-TRNG strains in Argentina seem to be highly homogeneous in terms of antimicrobial susceptibility, serogroup, plasmid profiles and even auxotype.

Adult↗
PubMed1999

Neisseria gonorrhoeae in Newcastle upon Tyne 1995-1997: increase in ciprofloxacin resistance.

Fluoroquinolones and third generation cephalosporins are the most effective antimicrobial agents for the treatment of gonorrhoea. However, clinically significant resistance to fluoroquinolones in Neisseria gonorrhoeae has been reported worldwide including Britain. The aim of this analysis was to study the factors relating to ciprofloxacin resistance and treatment failure. A total of 201 patients attending the Newcastle Genitourinary Medicine (GUM) clinic from 1995-1997 who were diagnosed with culture positive gonorrhoea was analysed. Treatment failure rates for ciprofloxacin were determined and the minimum inhibitory concentration (MIC) was measured for all cases of treatment failure. The case notes of all patients who had strains with MICs of ciprofloxacin in the resistant range (>0.05 microg/ml) were reviewed to determine the clinical outcome. The ciprofloxacin resistance with treatment failure was seen in 5% (8/160). All the 8 cases of treatment failure were heterosexual and had isolates resistant to penicillin and 4 cases (50%) were also resistant to tetracycline. All were sensitive to spectinomycin and ceftriaxone. Most of the cases probably acquired their infection from the Far East. As ciprofloxacin resistance seems to be associated with overseas exposure, changes in the standard treatment of gonorrhoea are not justified but consideration should be given to appropriate alternatives when the infection may have arisen from where such resistant strains are endemic. Monitoring fluoroquinolone resistance is now essential for ensuring adequate treatment of infections with resistant strains and for maximizing the time of usage of fluoroquinolones to treat gonorrhoea.

Adult↗
PubMed2005

Improvement of the bioluminescence reporter system for real-time monitoring of circadian rhythms in the cyanobacterium Synechocystis sp. strain PCC 6803.

Circadian rhythm is a self-sustaining oscillation whose period length coincides with the 24-hour day-night cycle. A powerful tool for circadian clock research is the real-time automated bioluminescence monitoring system in which a promoter region of a clock-controlled gene is fused to a luciferase reporter gene and rhythmic regulation of the promoter activity is monitored as bioluminescence. In the present study, we greatly improved the bioluminescence reporter system in the cyanobacterium Synechocystis sp. strain PCC 6803. We fused an 805-bp promoter region of the dnaK gene seamlessly to the luxA coding sequence and integrated the P(dnaK)::luxAB fusion gene into a specific intergenic region of the Synechocystis genome (targeting site 1). The resulting new reporter strain, PdnaK::luxAB(-), showed 12 times the bioluminescence intensity of the standard reporter strain, CFC2. Furthermore, we generated strain PdnaK::luxAB(+), in which the P(dnaK)::luxAB fusion gene and the selection-marker spectinomycin resistance gene are transcribed in opposite directions. The PdnaK::luxAB(+) strain showed 19 times the bioluminescence intensity of strain CFC2. The procedures used to increase the bioluminescence intensity are especially useful for bioluminescence monitoring of genes with low promoter activity. In addition, these reporter constructs facilitate bioluminescence monitoring of any gene because the promoter fragments they contain can easily be replaced by digestion with unique restriction enzymes. They would therefore contribute to a genome-wide analysis of gene expression in Synechocystis.

Circadian Rhythm↗
PubMed2004

A simple method for chloroplast transformation in Chlamydomonas reinhardtii.

Photosystem (PS)I is a multi-subunit pigment-protein complex that uses light energy to transfer electrons from plastocyanin to ferredoxin. Application of genetic engineering to photo-synthetic reaction center proteins has led to a significant advancement in our understanding of primary electron transfer events and the role of the protein environment in modulating these processes. Chlamydomonas reinhardtii provides a system particularly amenable to analyze the structure-function relationship of PSI. Chlamydomonas reinhardtii is also a favorable organism for chloroplast transformation because it contains a single chloroplast and grows heterotrophically when supplemented with acetate. Chlamydomonas has served as a model organism for the development of chloroplast transformation procedures and the study of photosynthetic mutants generated using this method. Exogenous cloned cpDNA can be introduced into the chloroplast by using this biolistic gene gun method. DNA-coated tungsten or gold particles are bombarded onto cells. Upon its entry into chloroplasts, the transforming DNA is released from the particles and integrated into the chloroplast genome through homologous recombination. The most versatile chloroplast selectable marker is aminoglycoside adenyl transferase (aadA), which can be expressed in the chloroplast to confer resistance to spectinomycin or streptomycin. This chapter describes the procedures for chloroplast transformation.

Animals↗
PubMed2002

Current concepts in the management of gonorrhoea.

The incidence of gonorrhoea is again rising in developed countries and a high disease rate has been maintained in less developed regions for a number of years. The need not only for treatment of the individual but also for control of gonorrhoea at a community level has increased significantly following recognition of its role in the amplification of human immunodeficiency virus (HIV) transmission. A sustainable decrease in the incidence of gonorrhoea and other sexually transmitted diseases (STDs) requires an integrated approach combining improved prevention, better diagnosis and optimal treatment. Effective antibiotic treatment is an essential element of this approach. However, antibiotic treatment of gonorrhoea has been severely hampered by the development of antibiotic resistance in Neisseria gonorrhoeae, to the extent that many therapies are no longer effective. Those treatments that retain acceptable efficacy are often unaffordable where they are most needed. Penicillins and tetracyclines should no longer be used in gonococcal disease, there are limitations on the effectiveness of newer macrolides and spectinomycin and in many parts of the world quinolones have been withdrawn from schedules for the treatment of gonorrhoea. Of all the current agents used to treat all forms of gonococcal disease, only the third generation cephalosporins (most notably ceftriaxone) have retained their efficacy; however, decreased susceptibility to these antibiotics has also appeared. Continuing reliance on antibiotic treatment for controlling gonorrhoea in the absence of other necessary approaches will see a further deterioration in the situation. In these circumstances the possibility that gonorrhoea will be untreatable becomes more real.

Cephalosporins↗
PubMed2001

Characterisation of some Ornithobacterium rhinotracheale strains and examination of their transmission via eggs.

The biochemical characteristics and antibiotic susceptibility of 12 Ornithobacterium rhinotracheale strains isolated from chickens and turkeys suffering from respiratory clinical signs and the survival of some isolates on egg-shell and within chicken eggs during hatching were examined. All O. rhinotracheale strains showed typical biochemical characteristics. Among the 16 drugs examined, penicillin G, ampicillin (MICs ranging from < or = 0.06 microgram/ml to 1 microgram/ml), ceftazidim (with MICs from < or = 0.06 microgram/ml to 0.12 microgram/ml), erythromycin, tylosin, tilmicosin (with some exceptions MICs ranged from < or = 0.06 microgram/ml to 1 microgram/ml) and tiamulin (MICs varied from < or = 0.06 microgram/ml to 2 micrograms/ml) were the most effective. Lincomycin, oxytetracycline and enrofloxacin also gave good inhibitions, but with most strains in a higher concentration (MICs ranged in most cases from 2 micrograms/ml to 8 micrograms/ml). The other antibiotics inhibited the growth of O. rhinotracheale only in very high concentrations (colistin) or not at all (apramycin, spectinomycin, polymyxin B). At 37 degrees C, O. rhinotracheale did not survive on egg-shell for more than 24 hours, while upon inoculation into embryonated chicken eggs it killed embryos by the ninth day, and from the 14th day post-inoculation no O. rhinotracheale could be cultured from the eggs at all. These results suggest that O. rhinotracheale is not transmitted via eggs during hatching.

Animals↗
PubMedDate not supplied

In vitro comparison of disk diffusion and agar dilution antibiotic susceptibility test methods for Neisseria gonorrhoeae.

At present, most Neisseria gonorrhoeae testing is done with beta-lactamase and agar dilution tests with common therapeutic agents. Generally, in bacteriological diagnosis laboratories in Argentina, study of antibiotic susceptibility of N. gonorrhoeae is based on beta-lactamase determination and agar dilution method with common therapeutic agents. The National Committee for Clinical Laboratory Standards (NCCLS) has recently described a disk diffusion test that produces results comparable to the reference agar dilution method for antibiotic susceptibility of N. gonorrhoeae, using a dispersion diagram for analyzing the correlation between both techniques. We obtained 57 gonococcal isolates from patients attending a clinic for sexually transmitted diseases in Tucumán, Argentina. Antibiotic susceptibility tests using agar dilution and disk diffusion techniques were compared. The established NCCLS interpretive criteria for both susceptibility methods appeared to be applicable to domestic gonococcal strains. The correlation between the MIC's and the zones of inhibition was studied for penicillin, ampicillin, cefoxitin, spectinomycin, cefotaxime, cephaloridine, cephalexin, tetracycline, norfloxacin and kanamycin. Dispersion diagrams showed a high correlation between both methods.

Colony Count, Microbial↗
PubMedDate not supplied

[Evaluation of antimicrobial sensitivity of 87 clinical isolates of vancomycin-resistant enterococci].

OBJECTIVES: 1) To evaluate the antimicrobial susceptibility pattern of vancomycin-resistant enterococci to the antimicrobial agents that are commonly used to treat enterococci infections and to some alternative drugs. 2) To evaluate the accuracy of E test for susceptibility testing enterococci. MATERIAL AND METHOD: We evaluated 87 clinical VRE isolates that were selected from a previous study which analyzed 1936 clinical isolates collected and processed in 97 US medical centers in the last quarter of 1992. The isolates were identified to the species level by using the API 20S System, the Vitek gram-positive identification cards and a modified version of the conventional method proposed by Facklam and Collins. The in vitro susceptibility testing was performed by broth microdilution, E test and disk diffusion methods, following the criteria described by the National Committee for Clinical Laboratory Standards (NCCLS). The VRE isolates were tested against antimicrobial agents commonly used to treat enterococci infections (vancomycin, teicoplanin, ampicillin, penicillin, gentamicin and streptomycin) and against ten potential alternative drugs (chloramphenicol, doxycycline, sparfloxacin, ciprofloxacin, clinafloxacin, erythromycin, spectinomycin, trospectomycin, trimetoprim-sulfametoxazol and novobiocin). RESULTS: Our results showed a high rate of resistance to ampicillin and penicillin (86%). High level resistance to gentamicin and streptomycin was demonstrated by 82% and 85% respectively. Although teicoplanin and vancomycin belong to the same antibiotic group (glycopeptide), 29% of VRE were susceptible to teicoplanin. Among the alternative drugs, trospectomycin, doxycyclin and chloramphenicol showed the highest in vitro activity, with 94%, 92% and 82% susceptibility respectively. In addition, erythromycin, trimetoprim-sulfametoxazol and ciprofloxacin showed the highest rates of resistance (98%, 83% and 69%, respectively). CONCLUSION: The treatment options for infections caused by vancomycin-resistant enterococci seem to be very narrow since a small percentage of those isolates were susceptible to the other antimicrobial agents commonly used to treat these infections and only a few of the alternative drugs tested showed good in vitro activity. Many regimens using various antibiotic combinations have been tested against VRE, most of them with fluoroquinolones. However further studies are necessary to evaluate the clinical role of these antibiotic combinations.

Anti-Bacterial Agents↗
PubMedDate not supplied

In vitro antibiotic resistance profiles of Ornithobacterium rhinotracheale strains from Minnesota turkeys during 1996-2002.

Antimicrobial resistance in nearly all human and animal pathogens is on the increase. In poultry, Ornithobacterium rhinotracheale has been identified as a newly emerging respiratory bacterial pathogen that has caused significant economic losses to the poultry industry. In this study, we examined in vitro antibiotic resistance profiles of 125 isolates of O. rhinotracheale isolated from turkeys in Minnesota during 1996-2002. A majority of isolates was sensitive to clindamycin, erythromycin, spectinomycin, and ampicillin. Resistance against sulfachloropyridiazine decreased from 1996 to 2002, but an increase in resistance was seen against gentamicin, ampicillin, trimethoprim sulfa, and tetracycline. The annual trend slopes for these antibiotics were 7.36%, 3.02%, 2.43%, and 1.95%, respectively. The resistance against penicillin remained constant from year to year with a trend slope of only 0.54% per year. These results emphasize the need for continued monitoring of O. rhinotracheale isolates for antibiotic resistance and establishment of baseline resistance pattern data for this organism. These data can then be used to design and evaluate local epidemiological interventions.

Animals↗
PubMedDate not supplied

Molecular characterization of plasmids with antimicrobial resistant genes in avian isolates of Pasteurella multocida.

The complete nucleotide sequences of two plasmids from avian isolates of Pasteurella multocida that caused outbreaks of fowl cholera in Taiwan were determined. The entire sequences of the two plasmids, designated as pJR1 and pJR2, were 6792 bp and 5252 bp. Sequence analysis showed that the plasmid pJR1 contained six major genes: the first gene (sulII) encoded a type II sulfonamide resistant dihydropteroate synthase, the second gene (tetG) encoded a tetracycline resistance protein, the third gene (catB2) encoded a chloramphenicol acetyltransferase, the fourth gene (rep) encoded a replication protein, and the fifth and sixth genes (mbeCy and deltambeAy) encoded proteins involved in the mobilization of plasmid. The plasmid pJR2 contained five major genes: the first gene (deltaintI1) encoded a truncated form of a type I integrase, the second gene (aadA1) encoded an aminoglycoside adenylyltransferase that confers resistance to streptomycin and spectinomycin, the third gene (blaP1) encoded a beta-lactamase that confers resistance to ampicillin and carbenicillin, and the fourth and fifth genes might encode proteins involved in the plasmid replication or segregation. Sequence comparisons showed that the antibiotic resistance genes found in pJR1 and pJR2 exhibited a high degree of sequence homology to the corresponding genes found in a great variety of gram-negative bacteria, including Escherichia coli, Salmonella enterica Typhimurium DT104, Psedomonas spp., P. multocida, Mannheimia spp., and Actinobacills pleuropneumoniae, which suggests that these resistance genes were disseminated in these bacteria. Although sulII and tetG genes were found previously in P. multocida or Mannheimia spp., this is the first report on the presence of catB2, aadA1, and blaP1 genes in bacteria of the family Pasturellaceae. Moreover, the aadA1 and blaP1 genes found in pJR2 were organized into an integron structure, which is a site-specific recombination system capable of capturing and mobilizing antibiotic resistance genes. This is also the first report on the presence of an integron in bacteria of the family Pasteurellaceae. The presence of a P. multocida integron might facilitate the spreading of antibiotic resistance genes between P. multocida and other gram-negative bacteria.

Animals↗