Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Spectinomycin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources
PubMed1984

Antibiotic resistance mutations in 16S and 23S ribosomal RNA genes of Escherichia coli.

Recombinant DNA and classic genetic procedures were used to map a spectinomycin resistance mutation to a 121 base pair region of a 16S RNA gene and a macrolide-lincosamide-streptogramin type B resistance mutation to a 32 base pair region of a 23S RNA gene. DNA sequence analysis of these regions revealed that spectinomycin resistance results from a C/G to T/A transition at position 1192 of a 16S RNA gene. Resistance to macrolide, lincosamide and streptogramin type B antibiotics results from an A/T to T/A transversion at position 2058 of a 23S RNA gene. The alteration in 16S RNA is in a sequence that can participate in alternate base pairing arrangements that have been proposed to be involved in the translocation process. The alteration in 23S RNA identifies sequences important to peptidyl transfer.

Base Sequence↗
PubMed1993

Two regions of the Escherichia coli 16S ribosomal RNA are important for decoding stop signals in polypeptide chain termination.

Two regions of the 16S rRNA, helix 34, and the aminoacyl site component of the decoding site at the base of helix 44, have been implicated in decoding of translational stop signals during the termination of protein synthesis. Antibiotics specific for these regions have been tested to see how they discriminate the decoding of UAA, UAG, and UGA by the two polypeptide chain release factors (RF-1 and RF-2). Spectinomycin, which interacts with helix 34, stimulated RF-1 dependent binding to the ribosome and termination. It also stimulated UGA dependent RF-2 termination at micromolar concentrations but inhibited UGA dependent RF-2 binding at higher concentrations. Alterations at position C1192 of helix 34, known to confer spectinomycin resistance, reduced the binding of f[3H]Met-tRNA to the peptidyl-tRNA site. They also impaired termination in vitro, with both factors and all three stop codons, although the effect was greater with RF-2 mediated reactions. These alterations had previously been shown to inhibit EF-G mediated translocation. As perturbations in helix 34 effect both termination and elongation reactions, these results indicate that helix 34 is close to the decoding site on the bacterial ribosome. Several antibiotics, hygromycin, neomycin and tetracycline, specific for the aminoacyl site, were shown to inhibit the binding and function of both RFs in termination with all three stop codons in vitro. These studies indicate that decoding of all stop signals is likely to occur at a similar site on the ribosome to the decoding of sense codons, the aminoacyl site, and are consistent with a location for helix 34 near this site.

Anti-Bacterial Agents↗
PubMed1994

Efficient targeting of foreign genes into the tobacco plastid genome.

The pPRV plasmids are vectors for targeted insertion of foreign genes into the tobacco plastid genome (ptDNA). The vectors are based on the pUC119 plasmid which replicates in E. coli but not in plastids. The spectinomycin resistance (aadA) gene and a multiple cloning site (MCS) are flanked by 1.8-kb and 1.2-kb ptDNA sequences. Biolistic delivery of vector DNA, followed by spectinomycin selection, yields plastid transformants at a reproducible frequency, approximately 1 transplastomic line per bombarded sample. The selected aadA gene and linked non-selectable genes cloned into the MCS are incorporated into the ptDNA by two homologous recombination events via the flanking ptDNA sequences. The transplastomes thus generated are stable, and are maternally transmitted to the seed progeny. The pPRV vector series targets insertions between the divergently transcribed trnV gene and the rps12/7 operon. The lack of readthrough transcription of appropriately oriented transgenes makes the vectors an ideal choice for the study of transgene promoter activity.

Base Sequence↗
PubMed2001

Antimicrobial susceptibility of Neisseria gonorrhoeae isolates from three Caribbean countries: Trinidad, Guyana, and St. Vincent.

BACKGROUND: The percentage of Neisseria gonorrhoeae isolates resistant to antimicrobial agents commonly used for treatment is unknown in many Caribbean countries. GOAL: To determine the antimicrobial susceptibility of N gonorrhoeae isolates from Trinidad (144 isolates), Guyana (70 isolates), and St. Vincent (68 isolates) so baseline data can be established for further studies, and to assist in establishing effective treatment guidelines. STUDY DESIGN: Consecutive urethral and endocervical specimens from several clinics were collected and identified as N gonorrhoeae. Isolates of N gonorrhoeae were tested for their susceptibility to penicillin, tetracycline, ceftriaxone, ciprofloxacin, spectinomycin, and azithromycin. The presumptive identification of penicillinase-producing N gonorrhoeae and/or tetracycline-resistant N gonorrhoeae isolates based on MIC was confirmed by plasmid and tetM content analysis. RESULTS: High percentages of penicillin and/or tetracycline resistance were observed in N gonorrhoeae isolates from Guyana (92.9%), St. Vincent (44.1%), and Trinidad (42.4%). Isolates from all three countries were susceptible to ceftriaxone, ciprofloxacin, and spectinomycin. One penicillinase-producing N gonorrhoeae/tetracycline-resistant N gonorrhoeae from Guyana had an MIC of 0.5 microg/l to ciprofloxacin. This and nine other isolates from Guyana also were resistant to azithromycin (defined as MIC > or = 2.0 microg/ml) as well as penicillin and tetracycline. A reduced susceptibility to azithromycin was displayed by 16% of the isolates from St. Vincent and 72% of the isolates from Guyana (MIC, 0.25-1.0 microg/ml). Most penicillinase-producing N gonorrhoeae isolates carried Africa-type plasmids (61/90), with 28 of 90 having Toronto-type plasmids and a single isolate carrying an Asia-type plasmid. The tetM determinant in tetracycline-resistant N gonorrhoeae isolates was predominantly of the Dutch type (68/91). CONCLUSIONS: The high prevalence of N gonorrhoeae isolates from 3 of 21 English- and Dutch-speaking Caricom countries in the Caribbean with either plasmid-mediated or chromosomal resistance to penicillin and tetracycline supports international observations that these drugs should not be used to treat gonococcal infections. The detection of isolates with reduced susceptibility to drugs such as azithromycin, which currently are recommended for treatment in the region, attest to the importance of the continued monitoring of gonococcal antimicrobial susceptibility for the maintenance of effective treatment guidelines.

Anti-Bacterial Agents↗
PubMed2003

High percentages of resistance to tetracycline and penicillin and reduced susceptibility to azithromycin characterize the majority of strain types of Neisseria gonorrhoeae isolates in Cuba, 1995-1998.

BACKGROUND: In many regions the susceptibility of Neisseria gonorrhoeae isolates to antimicrobial agents is rarely tested. The Gonococcal Antimicrobial Surveillance Program (GASP) in Cuba was established as part of a larger regional GASP program to facilitate the collection and reporting of antimicrobial susceptibility data for N gonorrhoeae isolates. GOAL: The goal was to retrospectively determine the antimicrobial susceptibility and molecular epidemiology of 91 isolates of N gonorrhoeae isolated from 11 centers in Cuba. STUDY DESIGN: Isolates of N gonorrhoeae were collected and presumptively identified from 11 Cuban provincial health centers. They were then forwarded to the National Laboratory of Pathogenic Neisseria Havana for confirmatory identification and were subsequently analyzed at the Center for GASP in Ottawa. Isolates were tested for susceptibility to penicillin, tetracycline, spectinomycin, ceftriaxone, ciprofloxacin, and azithromycin by the agar dilution method. To establish baseline data for molecular epidemiologic profiles, the auxotype (A), serovar (S), plasmid content (P), and TetM type of the isolates were determined. Certain A/S/P classes were further analyzed by pulsed field gel electrophoresis (PFGE). RESULTS: High percentages of the 91 N gonorrhoeae isolates were resistant to penicillin (68%) and tetracycline (83.5%), with 56% being penicillinase-producing (PPNG) and 64% carrying plasmid-mediated tetracycline resistance (TRNG; 50% were PP/TRNG). An additional 14% of the isolates carried chromosomal resistance (CMRNG) to either tetracycline or penicillin or both antibiotics. All isolates were susceptible to spectinomycin, ceftriaxone, and ciprofloxacin. However, nine isolates were resistant to azithromycin (MIC, > or = 1.0 microgram/ml), and 43 other isolates displayed reduced susceptibility to this antibiotic (MIC, 0.25-0.5 microgram/ml). Although a total of 21 different A/S classes were identified, most of the isolates (61) belonged to three A/S classes: NR/IA-6 (35 isolates), NR/IB-1 (15 isolates), and P/IA-6 (11 isolates). Thirty-two of 45 PP/TRNG were A/S class NR/IA-6, and nine of the P/IA-6 isolates were TRNG. By contrast, most of A/S class NR/IB-1 (8) were CMRNG. PFGE analysis following digestion with NheI or SpeI further clustered the isolates into separate groups. CONCLUSIONS: This study demonstrates high percentages of N gonorrhoeae isolates with penicillin and tetracycline resistance in Cuba. As has been noted in other studies in the Caribbean region and Latin America, resistance and reduced susceptibility to azithromycin are developing as emerging problems. Since penicillin and tetracycline continue to be widely used for the treatment of gonococcal infections in Cuba, this study indicates the importance of antimicrobial susceptibility surveillance so that effective antibiotics may be recommended for treatment of gonococcal infections.

Anti-Bacterial Agents↗
PubMed1989

Some properties of two erythromycin-dependent strains of Escherichia coli.

Strains of Escherichia coli can be isolated that require erythromycin for growth. With one strain, AM, a range of antibiotics, including chloramphenicol, tetracycline, spectinomycin, kasugamycin and rifampicin, will substitute for erythromycin on solid and in liquid media; nalidixic acid supports growth in liquid but not on solid media. With a second strain, 103, chloramphenicol, tetracycline and spectinomycin support growth in liquid media but on solid medium only chloramphenicol substitutes for erythromycin. In media of higher than normal ionic strength, strain AM, but not strain 103, can grow in the absence of antibiotics. Possible reasons for these complex phenotypes are discussed.

Aminoglycosides↗
PubMed1997

Epigenetic silencing of a foreign gene in nuclear transformants of Chlamydomonas.

The unstable expression of introduced genes poses a serious problem for the application of transgenic technology in plants. In transformants of the unicellular green alga Chlamydomonas reinhardtii, expression of a eubacterial aadA gene, conferring spectinomycin resistance, is transcriptionally suppressed by a reversible epigenetic mechanism(s). Variations in the size and frequency of colonies surviving on different concentrations of spectinomycin as well as the levels of transcriptional activity of the introduced transgene(s) suggest the existence of intermediate expression states in genetically identical cells. Gene silencing does not correlate with methylation of the integrated DNA and does not involve large alterations in its chromatin structure, as revealed by digestion with restriction endonucleases and DNase I. Transgene repression is enhanced by lower temperatures, similar to position effect variegation in Drosophila. By analogy to epigenetic phenomena in several eukaryotes, our results suggest a possible role for (hetero)chromatic chromosomal domains in transcriptional inactivation.

Animals↗
PubMed1992

Isolation and characterization of the aadA aminoglycoside-resistance gene from Salmonella choleraesuis.

The streptomycin- and spectinomycin-resistance gene of Salmonella choleraesuis was cloned and its nucleotide sequence determined. The gene is 789 bases long, encoding a protein of a predicted size of 29,353 Da. The gene product inactivated streptomycin and spectinomycin by an adenylation modification. It is homologous (c. 40% total identity) to streptomycin adenylyltransferase, a 3'(9)-O-nucleotidyltransferase (AAD(3')(9)), which is encoded by the aadA gene in Escherichia coli, Agrobacterium tumefaciens, Klebsiella pneumonia, and Serratia marcescens. The AadA protein of S. choleraesuis differs significantly from the other AadA proteins, indicating that it may have diverged from the other members of this family earlier in evolution. Southern hybridization analysis revealed that homologous aadA sequences were also present in other streptomycin-resistant Salmonella species.

Amino Acid Sequence↗
PubMed2000

Presence of 22-kDa protein reacting with sera in piglets experimentally infected with Brachyspira hyodysenteriae.

In order to examine the effect of spectinomycin on outbreaks of swine dysentery, experimental infection of piglets with Brachyspira hyodysenteriae was carried out. Feed with and without spectinomycin (SP) was given to each piglet ad libitum and the susceptibility of the piglets to infection with B. hyodysenteriae was compared between SP-treated and untreated piglets. The results showed that the SP-treated piglets did not display clinical signs of swine dysentery unlike the untreated piglets. The sera obtained from these piglets were examined by the microscopic agglutination test and antibodies to B. hyodysenteriae in both groups of experimentally infected piglets were detected and the reaction was serogroup-specific. The agglutination titers were very high in the untreated piglets with dysentery while the titers in the SP-treated piglets were lower than those in the untreated piglets. In addition, the immunoblotting technique was applied and the results demonstrated that 22- and 17-kDa proteins in strain ATCC 31212 (serogroup B) reacted strongly with the sera from the untreated piglets but not with the sera from the SP-treated piglets. The 22- and 17-kDa proteins also reacted with strain ATCC 27164 (serogroup A) which belongs to a different serogroup. The 22- and 17-kDa proteins were also confirmed in six other strains of B. hyodysenteriae which belong to six different serogroups. These proteins were sensitive to proteinase K. These results indicate that the 22- and 17-kDa proteins are common to eight strains of B. hyodysenteriae which differ serologically from each other.

Agglutination Tests↗
PubMed1973

Comparison of five aminocyclitol antibiotics in vitro against Enterobacteriaceae and Pseudomonas.

The in vitro susceptibility of 163 strains of Enterobacteriaceae and 23 isolates of Pseudomonas aeruginosa to various concentrations of gentamicin, kanamycin, spectinomycin, tobramycin, and BB-K8, a new semisynthetic aminoglycoside antibiotic, was determined. Studies were performed in Mueller-Hinton agar and broth, and two different sizes of bacterial inocula were used. On a weight basis, gentamicin and tobramycin demonstrated comparable activity in vitro and were the most active of the five drugs tested against Escherichia coli, Klebsiella, Enterobacter, and Proteus species. All of these organisms were inhibited by gentamicin or tobramycin at concentrations of 5.0 mug or less/ml in agar with both inocula of bacterial cells. In addition, tobramycin was the most active drug against isolates of P. aeruginosa and gentamicin was the most active against Salmonella and Shigella species. Although kanamycin and BB-K8 demonstrated a high degree of activity against most Enterobacteriaceae, they were not the most active agents tested for any genus. Spectinomycin was the least active compound, and many isolates grew in concentrations higher than those readily attainable in serum.

Aminobutyrates↗
PubMed1987

Changing antibiotic susceptibility of Neisseria gonorrhoeae in Franceville, Gabon.

Susceptibilities to penicillin, cefotaxime, kanamycin, tetracycline, and spectinomycin were measured for 5 reference strains and 302 Neisseria gonorrhoeae isolates collected between 1980 and 1985. After an initial rise, the number of penicillinase-producing strains decreased. A gradual decrease in susceptibility to spectinomycin and the appearance of tetracycline-resistant strains were also documented.

Anti-Bacterial Agents↗
PubMed1988

In vitro culture system to determine MICs and MBCs of antimicrobial agents against Treponema pallidum subsp. pallidum (Nichols strain).

A new procedure for determining the susceptibility of Treponema pallidum subsp. pallidum to antimicrobial agents was developed, utilizing a tissue culture system which promotes the in vitro multiplication of this organism. In the absence of antibiotics, T. pallidum (Nichols virulent strain) multiplied an average of 10-fold when incubated for 7 days in the presence of Sf1Ep cottontail rabbit epithelial cell cultures. Varied concentrations of penicillin G, tetracycline, erythromycin, and spectinomycin were added to triplicate cultures to determine their effects on treponemal multiplication, motility, and virulence. The MIC of each antibiotic was defined as the lowest concentration which prevented treponemal multiplication, whereas the MBC was defined as the lowest concentration which abrogated the ability of the cultured treponemes to multiply and cause lesions in rabbits. The in vitro culture technique provided highly reproducible MICs and (in parentheses) MBCs of each of the antibiotics tested: aqueous penicillin G, 0.0005 (0.0025) microgram/ml; tetracycline, 0.2 (0.5) microgram/ml; erythromycin, 0.005 (0.005) microgram/ml; and spectinomycin, 0.5 (0.5) microgram/ml. The significance of these results in light of the in vivo activities and the previous in vitro evaluations of these antibiotics is discussed. The T. pallidum in vitro cultivation system shows promise as a method for studying the interaction between T. pallidum and antimicrobial agents and for screening new antibiotics for syphilis therapy.

Animals↗
PubMed1989

Antibacterial activity of trospectomycin (U-63366F) and initial evaluations of disk diffusion susceptibility tests.

The in vitro activities of trospectomycin sulfate were compared with those spectinomycin against 632 aerobic microorganisms, including 66 Neisseria gonorrhoeae isolates. Against species other than gram-negative bacilli, trospectomycin was about 4- to 16-fold more active than spectinomycin. For disk diffusion tests, a 30-micrograms disk is recommended, with tentative zone size breakpoints of less than or equal to 13 mm for resistance (MIC, greater than or equal to 64 micrograms/ml) and greater than or equal to 17 mm for susceptibility (MIC, less than or equal to 16 micrograms/ml).

Anti-Bacterial Agents↗
PubMed1990

Quantification of antibiotic drug potency by a two-compartment radioassay of bacterial growth.

The two-compartment radioassay for microbial kinetics based on continuous measurement of the 14CO2 released by bacterial metabolism of 14C-labeled substrate offers a valuable approach to testing the potency of antimicrobial drugs. By using a previously validated radioassay with gram-positive and gram-negative bacteria, a group of protein synthesis inhibitors was evaluated for their effect on microbial growth kinetics. All tested drugs induced changes in both the slopes and intercepts of the growth curves. An exponential growth model was applied to quantify the drug effect on the processes of bacterial 14CO2 liberation and cell generation. The response was measured in terms of a generation rate constant. A linear dependence of the generation rate constant on the dose of spectinomycin was observed with Escherichia coli. Sigmoidal-shaped curves were found in the assays of chloramphenicol and tetracycline. The implications of dose-response curves are discussed on the basis of the receptor site concept for drug action. The assay sensitivities for chloramphenicol and tetracycline were similar to those obtained by the cell counting method, but the sensitivity of the radioassay was at least 10 times greater for spectinomycin.

Anti-Bacterial Agents↗
PubMed2005

Frequency of spontaneous mutations that confer antibiotic resistance in Chlamydia spp.

Mutations in rRNA genes (rrn) that confer resistance to ribosomal inhibitors are typically recessive or weakly codominant and have been mostly reported for clinical strains of pathogens possessing only one or two rrn operons, such as Helicobacter pylori and Mycobacterium spp. An analysis of the genome sequences of several members of the Chlamydiaceae revealed that these obligate intracellular bacteria harbor only one or two sets of rRNA genes. To study the contribution of rRNA mutations to the emergence of drug resistance in the Chlamydiaceae, we used the sensitivities of Chlamydia trachomatis L2 (two rrn operons) and Chlamydophila psittaci 6BC (one rrn operon) to the aminoglycoside spectinomycin as a model. Confluent cell monolayers were infected in a plaque assay with about 10(8) wild-type infectious particles and then treated with the antibiotic. After a 2-week incubation time, plaques formed by spontaneous spectinomycin-resistant (Spc(r)) mutants appeared with a frequency of 5 x 10(-5) for C. psittaci 6BC. No Spc(r) mutants were isolated for C. trachomatis L2, although the frequencies of rifampin resistance were in the same range for both strains (i.e., 10(-7)). The risk of emergence of Chlamydia strains resistant to tetracyclines and macrolides, the ribosomal drugs currently used to treat chlamydial infections, is discussed.

Animals↗
PubMed2006

Influences of biofilm structure and antibiotic resistance mechanisms on indirect pathogenicity in a model polymicrobial biofilm.

Indirect pathogenicity (IP), the commensal protection of antibiotic-sensitive pathogens by resistant microorganisms of low intrinsic virulence, can prevent the eradication of polymicrobial infections. The contributions of antibiotic resistance mechanisms and biofilm structure to IP within polymicrobial biofilms were investigated using a model two-member consortium. Escherichia coli ATCC 33456 was transformed with vectors conferring either ampicillin or spectinomycin resistance, creating two distinct populations with different resistance mechanisms. Each strain alone or the consortium was grown as biofilms in flow cells and planktonically in chemostats. Comparisons in survival and activity were made on the basis of MICs and minimum biofilm preventative concentrations, a newly introduced descriptor. In ampicillin-containing medium, commensal interactions were evident during both modes of cultivation, but the sensitive strain experienced a greater benefit in the chemostat, indicating that the biofilm environment limited the commensal interaction between the Amp(r) and Spt(r) strains. In spectinomycin-containing medium, growth of the sensitive strain in chemostats and biofilms was not aided by the resistant strain. However, green fluorescent protein expression by the sensitive strain was greater in mixed-population biofilms (9% +/- 1%) than when the strain was grown alone (2% +/- 0%). No comparable benefit was evident during growth in the chemostat, indicating that the biofilm structure contributed to enhanced activity of the sensitive strain.

Ampicillin↗
PubMed2003

Nitrogen-regulated hypermutator strain of Synechococcus sp. for use in in vivo artificial evolution.

Artificially evolved variants of proteins with roles in photosynthesis may be selected most conveniently by using a photosynthetic organism, such as a cyanobacterium, whose growth depends on the function of the target protein. However, the limited transformation efficiency of even the most transformable cyanobacteria wastes much of the diversity of mutant libraries of genes produced in vitro, impairing the coverage of sequence space. This highlights the advantages of an in vivo approach for generating diversity in the selection organism itself. We constructed two different hypermutator strains of Synechococcus sp. strain PCC 7942 by insertionally inactivating or nutritionally repressing the DNA mismatch repair gene, mutS. Inactivation of mutS greatly increases the mutation rate of the cyanobacterium's genes, leading to an up-to-300-fold increase in the frequency of resistance to the antibiotics rifampin and spectinomycin. In order to control the rate of mutation and to limit cellular damage resulting from prolonged hypermutation, we placed the uninterrupted mutS gene in the cyanobacterial chromosome under the transcriptional control of the cyanobacterial nirA promoter, which is repressed in the presence of NH(4)(+) as an N source and derepressed in its absence. By removing or adding this substrate, hypermutation was activated or repressed as required. As expected, hypermutation caused by repression in PnirA-mutS transformants led to an accumulation of spectinomycin resistance mutations during growth.

Adenosine Triphosphatases↗
PubMed2004

New integrative method to generate Bacillus subtilis recombinant strains free of selection markers.

The novel method described in this paper combines the use of blaI, which encodes a repressor involved in Bacillus licheniformis BlaP beta-lactamase regulation, an antibiotic resistance gene, and a B. subtilis strain (BS1541) that is conditionally auxotrophic for lysine. We constructed a BlaI cassette containing blaI and the spectinomycin resistance genes and two short direct repeat DNA sequences, one at each extremity of the cassette. The BS1541 strain was obtained by replacing the B. subtilis P(lysA) promoter with that of the P(blaP) beta-lactamase promoter. In the resulting strain, the cloning of the blaI repressor gene confers lysine auxotrophy to BS1541. After integration of the BlaI cassette into the chromosome of a conditionally lys-auxotrophic (BS1541) strain by homologous recombination and positive selection for spectinomycin resistance, the eviction of the BlaI cassette was achieved by single crossover between the two short direct repeat sequences. This strategy was successfully used to inactivate a single gene and to introduce a gene of interest in the Bacillus chromosome. In both cases the resulting strains are free of selection marker. This allows the use of the BlaI cassette to repeatedly further modify the Bacillus chromosome.

Anti-Bacterial Agents↗