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PubMed2005

Class 1 integron-associated gene cassettes in Salmonella enterica subsp. enterica serovar Agona isolated from pig carcasses in Brazil.

OBJECTIVES: Two multiresistant Salmonella enterica subsp. enterica serovar Agona isolates from pig carcasses were investigated for antimicrobial resistance genes and their location with particular reference to the detection of class 1 integrons. METHODS: The two S. Agona isolates were investigated for their in vitro susceptibility to antimicrobial agents and their plasmid content. The resistance genes and class 1 amplicons were identified by PCR assays. Amplicons of class 1 integrons were cloned and sequenced. Transferability of resistance plasmids was confirmed by conjugation. RESULTS: Both S. Agona isolates carried conjugative plasmids of approximately 150 kb which harboured all resistance genes detected in the respective isolates. S. Agona 231 was resistant to chloramphenicol by catA1, to tetracycline and minocycline by tet(B), and to sulphonamides by sul1. In addition, it harboured a streptomycin resistance gene strA and a class 1 integron with a new aadA variant designated aadA23, which mediates resistance to streptomycin and spectinomycin. S. Agona 242 also carried the genes catA1, tet(B), and sul1. Moreover, it harboured a second sulphonamide resistance gene, sul2, and a class 1 integron with intact gene cassettes carrying new variants of the trimethoprim resistance gene dfrA15b or the chloramphenicol resistance gene cmlA4. The third gene cassette consisted of a truncated aadA2 gene. CONCLUSIONS: The results of this study show that large conjugative multiresistance plasmids are present in S. Agona from pigs. Analysis of the class 1 integrons revealed the presence of new variants of resistance genes so far not detected in Salmonella isolates.

Abattoirs↗
PubMed2005

Genetic basis for dissemination of armA.

OBJECTIVES AND METHODS: armA is a novel plasmid-borne 16S rRNA methyltransferase that confers high-level resistance to 4,6-disubstituted deoxystreptamines. Recently, we have isolated from a high-level broad-spectrum aminoglycoside-resistant Escherichia coli animal isolate a plasmid, pMUR050, that bore the armA gene. In order to elucidate the genetic basis for the spread of armA, we have determined the complete nucleotide sequence of pMUR050. RESULTS: armA was borne by a complex transposon composite flanked by two direct repeats of IS26. The transposon composite included a class one integron with sul1 for resistance to sulphonamides and ant3''9 conferring resistance to spectinomycin-streptomycin, and a macrolide efflux pump and mefE/mel conferring high-level resistance to erythromycin. We identified in GenBank that another plasmid, pCTX-M3, from a Polish Citrobacter freundii human isolate, bore the same genetic structure, including armA. CONCLUSIONS: armA is present in human and animal isolates within a novel transposon composite. Further spread of armA between bacteria of diverse origin is to be expected.

Aminoglycosides↗
PubMed2005

Molecular mechanisms of resistance in multidrug-resistant serovars of Salmonella enterica isolated from foods in Germany.

OBJECTIVES: The objectives of this study were to determine antimicrobial susceptibility and to characterize the molecular mechanisms of multidrug resistance among German food-borne Salmonella isolates of different serovars. METHODS: A total of 319 epidemiologically independent multidrug-resistant isolates from German foodstuffs comprising 25 different serovars were tested for their antimicrobial susceptibility by broth microdilution. The presence of antimicrobial resistance genes, integrons of classes 1 and 2 and their integrated resistance gene cassettes as well as the Salmonella genomic island 1 (SGI1) was investigated by PCR and DNA sequencing. Localization of integrons and relevant resistance genes was done by Southern hybridization. Sequence analysis revealed mutations in the quinolone resistance-determining region of the gyrA gene. RESULTS: The most prevalent resistances found in the multidrug-resistant serovars of Salmonella enterica from foods were to streptomycin (94%), sulfamethoxazole (92%), tetracycline (81%), ampicillin (73%), spectinomycin (72%), chloramphenicol (48%) and trimethoprim (27%). Twenty-four resistance genes covering six antimicrobial families (beta-lactams, aminoglycosides, phenicols, sulphonamides, tetracycline, and trimethoprim) were identified in the food isolates, many of them integrated as gene cassettes in class 1 and class 2 integrons. Class 1 integrons were detected in 65% of the multidrug-resistant Salmonella isolates comprising 16 different serovars, while class 2 integrons were found in 10% of the isolates belonging to two serovars only. The results demonstrate a clear predominance of both SGI1-borne resistance genes and class 1 integrons in Salmonella serovar Typhimurium DT104 and of class 2 integrons in Salmonella serovar Paratyphi B (d-tartrate positive). Nalidixic acid resistance found in 15% of the isolates was associated with single mutations in the gyrA gene. CONCLUSIONS: This study confirms the role of foods of animal and other origin as a reservoir of multidrug-resistant Salmonella and underlines the need for continuing surveillance of food-borne zoonotic bacterial pathogens along the food chain.

Anti-Bacterial Agents↗
PubMed2006

Phenotypic and genotypic characterization of antimicrobial resistance in Escherichia coli O111 isolates.

OBJECTIVES: The aim of this study was to generate baseline data on the prevalence and molecular basis of antimicrobial resistance in Escherichia coli O111 isolates. METHODS: A total of 105 epidemiologically unrelated E. coli O111 isolates from humans and cattle (isolated between 1983 and 2003) were tested for susceptibility to 17 antimicrobial agents by broth microdilution. Resistant isolates were screened by molecular methods for resistance genes, class 1 and 2 integrons and mutations in the quinolone-resistance determining regions. RESULTS: Resistance was found in 76% of the isolates, with a prevalence of 72% for multiresistance. The most prevalent resistances were to streptomycin, sulfamethoxazole and tetracycline (72-68%), followed by spectinomycin, ampicillin and kanamycin/neomycin (39-25%). For each antimicrobial agent, the predominant resistance genes were ampicillin, bla(TEM) (94%); chloramphenicol, catA1 (100%); gentamicin, aac(3)-IV and aac(3)-II (50% each); kanamycin, aphA1 (100%); streptomycin, aadA1- like (66%); sulfamethoxazole, sul1 (59%); tetracycline, tet(A) (86%); and trimethoprim, dfrA1-like (83%). Class 1 integrons were found in 41% of the isolates. They carried aadA1, dfrA1-aadA1 and dfrA15-aadA1. A class 2 integron (dfrA1-sat1-aadA1) was found in one isolate. Only three isolates (3%) were resistant to nalidixic acid (reduced susceptibility to ciprofloxacin), with a single mutation in the gyrA gene. CONCLUSIONS: E. coli O111 strains exhibit a wide repertoire of genetic elements to sustain antimicrobial pressure. Two specific antimicrobial resistance pheno/genotypes, [STR-SPT]-SUL-TET/aadA1-sul1-tet(A) and STR-SUL-TET-AMP-[KAN-NEO]/strA/B-sul2-tet(A)-bla(TEM)-aphA1, are predominant.

Animals↗
PubMed2006

Characterization of acquired beta-lactamases and their genetic support in multidrug-resistant Pseudomonas aeruginosa isolates in Taiwan: the prevalence of unusual integrons.

OBJECTIVES: The present study was conducted to investigate acquired beta-lactamases and their genetic support in 26 Pseudomonas aeruginosa isolates that were resistant to nearly all antipseudomonal drugs from six medical centres in Taiwan. METHODS: Acquired beta-lactamases and their genetic support were determined by PCR-based strategies. RESULTS: Four and 16 of the 26 isolates were found to produce VIM-2 and VIM-3 metallo-beta-lactamases (MBLs), respectively, and 1, 1 and 2 isolates produced OXA-17, OXA-10 and PSE-1, respectively. These bla genes are all in class 1 integrons that are probably chromosomally located. The bla(VIM-3)-containing integron, with a deletion between int1 and the bla(VIM-3) structural gene, has six gene cassettes, bla(VIM-3), a probable fosfomycin resistance determinant, aacA4, aacA4, aadB and aacA4. The bla(VIM-2)-containing integron, without detectable 5'-conserved segment, contains four genes cassettes (aacA7-bla(VIM-2)-dhfr-aacA5) and is ended by tniC. The bla(OXA-10)-containing integron includes a catB3 cassette and a fused gene cassette, which is made up of bla(OXA-17) and a novel streptomycin-spectinomycin gene, designated aadA15. The bla(OXA-17)-containing integron has three gene cassettes (aacA4-catB2-bla(OXA-17)) but the 59-base element of the bla(OXA-17) cassette is interrupted by a putative transposase gene. The bla(PSE-1)-containing integron has three gene cassettes, aacA4, an aadA3-related gene designated aadA3b and bla(PSE-1). PFGE revealed genetic diversity among the multidrug-resistant isolates from different hospitals. CONCLUSIONS: This study demonstrated the high prevalence of VIM-type MBLs and the presence of unusual bla-encoding integrons in multidrug-resistant P. aeruginosa isolates in Taiwan. The spread of bla(VIM-2)-related genes by horizontal transfer might have occurred.

Anti-Bacterial Agents↗
PubMed2006

Proteus mirabilis clinical isolate harbouring a new variant of Salmonella genomic island 1 containing the multiple antibiotic resistance region.

OBJECTIVES: A clinical isolate of Proteus mirabilis strain 18306, which displayed the multidrug resistance phenotype of Salmonella genomic island 1 (SGI1), was examined for the presence of this island including its multiple antibiotic resistance genomic region. METHODS: P. mirabilis 18306 was isolated in March 2006 from a patient in Palestine with diabetic foot infection. Antibiotic susceptibility tests and various molecular techniques, including PCR, cloning and DNA sequencing were used for detection and characterization of SGI1 in P. mirabilis 18306. RESULTS: P. mirabilis 18306 showed the typical multidrug resistance phenotype of SGI1 as it was resistant to ampicillin, chloramphenicol, streptomycin, sulphonamides and tetracycline, in addition to trimethoprim and nalidixic acid. Molecular characterization showed that P. mirabilis 18306 harboured a structure similar to SGI1, except that the aadA2 gene, which confers resistance to streptomycin and spectinomycin, of standard SGI1 had been replaced with dfrA15, which confers resistance to trimethoprim. Furthermore, the nucleotide sequence of the extrachromosomal circular form of SGI1 in P. mirabilis was found to be identical to that of Salmonella Typhimurium DT104. However, PCR results showed that P. mirabilis 18306 was negative for the left and right junctions which represent the integration sites of SGI1 into Salmonella enterica chromosome. Hence, this new variant of SGI1 may be integrated at a different site into the chromosome of P. mirabilis 18306. Tn1826-derived class 2 integron, which carries only two gene cassettes, sat2 and aadA1, was also identified in this strain. CONCLUSIONS: In this study, we identified a new variant SGI1 containing the multiple resistance genomic region in a multidrug-resistant strain of P. mirabilis. This is the first report for SGI1 in a genus other than Salmonella.

Anti-Bacterial Agents↗
PubMed1982

Insertion sites and the terminal nucleotide sequences of the Tn4 transposon.

The nucleotide sequences at the ends of the Tn4 transposon (mercury spectinomycin and sulfonamide resistance) have been determined. They are inverted repeated sequences of 38 nucleotides with three mismatched base pairs. These sequences are strongly homologous with the terminal sequences of Tn501 (mercury resistance) but less so with those of Tn3 (ampicillin resistance). The Tn4 transposon generates pentanucleotide members (Tn3, Tn1000, Tn501, Tn551, IS2) with the exception of Tn1721 and bacteriophage Mu. Among the three Tn4 insertion sites examined here, two of them occurred near a nonanucleotide sequence in perfect homology with part of the terminal inverted-repeat sequence of Tn4 and the third insertion occurred near a sequence of partial homology to one end of Tn4. All three insertions were in the same orientation such that IRb is proximal to its homologous sequence on the recipient DNA.

Base Composition↗
PubMed1991

Transgenic expression of aminoglycoside adenine transferase in the chloroplast: a selectable marker of site-directed transformation of chlamydomonas.

Expression vectors for Chlamydomonas reinhardtii chloroplast transformation have been constructed with transcription and translation signals from chloroplast genes. The bacterial aadA sequence, coding for aminoglycoside 3" adenyl transferase, was inserted in these vectors and introduced into the C. reinhardtii chloroplast by particle gun transformation. The stable transgenic expression of this foreign protein in the chloroplast confers spectinomycin and streptomycin resistance to the transformed cells. This new marker can be used as a reporter of gene expression, and as a portable selectable cassette for chloroplast reverse genetics. Targetted gene disruption mutants of loci required for photosynthesis, tscA and psaC, were thus obtained. A gene disruption of an unidentified open reading frame, ORF472, remained heteroplasmic, suggesting that it has a vital function.

Base Sequence↗
PubMed1999

Expression of the human immunodeficiency virus frameshift signal in a bacterial cell-free system: influence of an interaction between the ribosome and a stem-loop structure downstream from the slippery site.

A-1 frameshift event is required for expression of the pol gene when ribosomes translate the mRNA of human immunodeficiency virus type-1 (HIV-1). In this study, we inserted the frameshift region of HIV-1 (a slippery heptanucleotide motif followed by a stem-loop) in a reporter gene coding for firefly luciferase. The ability of the corresponding mRNA, generated by in vitro transcription, to be translated in an Escherichia coli cell-free extract is the first demonstration that the HIV-1 frameshift can be reproduced in a bacterial cell-free extract, providing a powerful approach for analysis of the frameshift mechanism. The responses of the frameshift signal to chloramphenicol, an inhibitor of peptide bond formation, and spectinomycin, an inhibitor of translocation, suggest that the frameshift complies with the same rules found in eukaryotic translation systems. Furthermore, when translation was performed in the presence of streptomycin and neamine, two error-inducing antibiotics, or with hyperaccurate ribosomes mutated in S12, the frameshift efficiency was increased or decreased, respectively, but only in the presence of the stem-loop, suggesting that the stem-loop can influence the frameshift through a functional interaction with the ribosomes.

Animals↗
PubMed1996

Genetic engineering of the processing site of D1 precursor protein of photosystem II reaction center in Chlamydomonas reinhardtii.

The D1 protein (D1) of photosystem II (PSII) reaction center is synthesized as a precursor (pD1) and then processed at its carboxyl terminus to establish the function of water cleavage. The amino acid sequence of the carboxyl terminal extension excised by this process is poorly conserved except for a residue after the cleavage site at position of 345. We have constructed a vector for site-directed mutagenesis of the chloroplast psbA gene encoding D1 of the green alga, Chlamydomonas reinhardtii. The vector enables one to transform the chloroplasts of a psbA deletion mutant (Fud7) and directly select transformants for resistance to spectinomycin. Using this transforming vector, we have substituted Ser345 to Gly, Cys, Val and Phe in order to investigate effects of the amino acid side chain at this position on the processing rate. All of the resulting transformants exhibited the PSII activity as wild type and grew normally under photoautotrophic conditions even under strong light where rapid turnover of D1 protein is expected to occur. Western blotting analysis demonstrated that mature D1 accumulates in these transformants at wild type level. Pulse and chase labeling of chloroplast-encoded proteins using [35S] sulfate revealed that the processing of D1 precursor protein occurs in all four transformants as efficiently as in wild type, at least under the experimental conditions examined. The results suggest that either the amino acid side chain at position of 345 (+1 position) is not crucial to the enzymatic cleavage of pD1 in vivo or the apparent rate of processing in vivo is not limited by the enzymatic cleavage.

Animals↗
PubMed2004

Production of polyhydroxybutyrate by polycistronic expression of bacterial genes in tobacco plastid.

Transgenic techniques are used to enhance and improve crop production, and their application to the production of chemical resources in plants has been under investigation. To achieve this latter goal, multiple-gene transformation is required to improve or change plant metabolic pathways; when accomplished by plant nuclear transformation, however, this procedure is costly and time consuming. We succeeded in the metabolic engineering of the tobacco plant by introducing multiple genes within a bacteria-like operon into a plastid genome. A tobacco plastid was transformed with a polycistron consisting of the spectinomycin resistance gene and three bacterial genes for the biosynthesis of the biodegradable polyester, poly[(R)-3-hydroxybutyrate] (PHB), after modification of their ribosome binding sites. DNA and RNA analysis confirmed the insertion of the introduced genes into the plastid genome and their polycistronic expression. As the result, the transplastomic tobacco accumulated PHB in its leaves. The introduced genes and the PHB productivity were maternally inherited, avoiding genetic spread by pollen diffusion, and were maintained stably in the seed progeny. Despite the low PHB productivity, this report demonstrates the feasibility of transplastomic technology for metabolic engineering. This "phyto-fermentation" system can be applied to plant production of various chemical commodities and pharmaceuticals.

Base Sequence↗
PubMedDate not supplied

Clinical antibiotic resistance of Ureaplasma urealyticum.

The antibiotic sensitivity of strains of Ureaplasma urealyticum is measured usually by a metabolism inhibition technique. Antibiotic-resistant strains have been detected, usually not by testing many randomly collected strains but by testing organisms recovered from patients after treatment. On this selection basis about 10% of strains isolated between 1973 and 1976 from patients with nongonococcal urethritis attending sexually transmitted disease clinics in London were resistant to tetracyclines, as were strains isolated in 1983 to 1984. Such resistant strains are not confined to population groups that receive tetracyclines frequently and have been found in widespread geographic locations. About 40% of tetracycline-resistant strains in the London area also are resistant to erythromycin in contrast to about 10% of tetracycline-sensitive strains. Development of resistance to tetracycline, erythromycin, rosaramicin and spectinomycin by a Ureaplasma strain (serovar 2) isolated from a hypogammaglobulinemic patient in the United Kingdom has been seen following successive treatment with these antibiotics, but multiple antibiotic resistance of this kind must be rare.

Anti-Bacterial Agents↗
PubMedDate not supplied

Antibiotic sensitivities of Neisseria gonorrhoeae in the Far East: comparison of plasmid species in isolates from six countries.

In vitro susceptibility testing of 36 strains of Neisseria gonorrhoeae isolated in the Far East in 1979 and 1980 demonstrated that 27 penicillinase-producing (PPNG) isolates and nine non-penicillinase-producing (non-PPNG) isolates were susceptible to chloramphenicol, thiamphenicol, spectinomycin, trimethoprim-sulfamethoxazole, cefoperazone, moxalactam, cefotaxime, and ceftriaxone. In comparison, 50% of the strains had MICs of tetracycline of greater than 2 micrograms/ml, and 75% had MICs, of streptomycin of greater than 128 micrograms/ml. Eighty-two per cent of PPNG and 100% of non-PPNG isolates examined had MICs of kanamycin of greater than 32 micrograms/ml. None of the nine non-PPNG strains had MICs of ampicillin and penicillin of greater than 1 microgram/ml. A 4.4-megadalton plasmid, previously associated with beta-lactamase production, was found in all 27 PPNG isolates examined; 93% of PPNG and 22% of non-PPNG isolates contained a 24-megadalton plasmid previously associated with transfer of the 4.4-megadalton plasmid.

Ampicillin↗
PubMedDate not supplied

Ceftizoxime (FK-749) is effective therapy for urethritis caused by penicillinase-producing Neisseria gonorrhoeae.

Fifty-five men with culture-proved gonococcal urethritis caused by either penicillin-sensitive or penicillinase-producing Neisseria gonorrhoeae were treated with 1 g of ceftizoxime given intramuscularly. All patients were cured, including 26 (47%) with penicillinase-producing strains. Patients experienced no local or systemic side effects and tolerated the injection of ceftizoxime well. These results show that ceftizoxime is an effective alternative to either spectinomycin or cefoxitin in treatment of uncomplicated gonococcal urethritis caused by penicillin-resistant bacteria.

Cefotaxime↗
PubMedDate not supplied

Susceptibility of Neisseria gonorrhoeae to rifampicin and thiamphenicol: correlation with protein I antigenic determinants.

Tests of susceptibility to thiamphenicol and rifampicin were done for 85 strains of Neisseria gonorrhoeae, including 28 beta-lactamase-producing and three spectinomycin-resistant isolates. Strains were serogrouped by co-agglutination with 14 monoclonal antibodies that are specific for different antigenic determinants on protein I of the gonococcal outer membrane. Thus the isolates could be classified into one of the serogroups WI, WII, or WIII and could be subgrouped further into several serovars. The minimal inhibitory concentration (MIC) of thiamphenicol ranged between 0.125 and 4.0 micrograms/ml and that of rifampicin between 0.016 and 4.0 micrograms/ml. All isolates with a MIC of rifampicin of greater than or equal to 0.5 microgram/ml had a MIC of thiamphenicol of greater than or equal to 2.0 micrograms/ml. Decreased susceptibility (thiamphenicol MIC, greater than or equal to 1.0 microgram/ml; rifampicin MIC, greater than or equal to 0.5 microgram/ml) to both drugs was correlated with serogroup WII specificity and also correlated with strains that belonged to serovars characterized by a positive reaction with the WII monoclonal antibody 2G2.

Bacterial Outer Membrane Proteins↗
PubMedDate not supplied

Susceptibility of penicillinase-producing and non-penicillinase-producing strains of Neisseria gonorrhoeae isolated in Durban, South Africa, to 15 beta-lactam antibiotics.

Using two different inoculum sizes (10(4) and 10(7) organisms), we tested 35 penicillinase-producing (PPNG) and 72 non-PPNG strains of Neisseria gonorrhoeae falling into three categories (penicillin-sensitive, intermediately resistant, and resistant) by the agar-dilution method against 15 beta-lactam antibiotics. With the exception of penicillin, ampicillin, amoxicillin, and cephradine, the isolates were uniformly sensitive to all the other antibiotics tested (including spectinomycin, tetracycline, rosoxacin, sulfamethoxazole-trimethoprim [19:1 ratio], and kanamycin). Ceftriaxone and cefotaxime were the two most active compounds tested; all strains were inhibited at concentrations of 0.007 and 0.015 microgram/ml, respectively. Isolates with intrinsic resistance to penicillin were less susceptible to cefoxitin and cefuroxime than were PPNG strains. The effect of inoculum size varied for the different antibiotics; penicillin and cefaclor showed this effect only with PPNG strains, whereas for ampicillin and amoxicillin it was also seen with non-PPNG strains. Cephamandole showed this effect with both penicillin-sensitive and PPNG strains. In view of the increasing resistance to penicillin, we would recommend that alternative drugs be used as first line therapy for gonorrhea in South Africa.

Anti-Bacterial Agents↗
PubMedDate not supplied

Penicillinase-producing Neisseria gonorrhoeae in Dade County, Florida: phenotypic characterization of isolates from 1983, 1984, and 1986.

Penicillinase-producing strains of Neisseria gonorrhoeae (PPNG) have been endemic in Miami, Florida, since 1981. Strains of PPNG isolated in Miami during 1983 (60 isolates), 1984 (41 isolates), and 1986 (107 isolates) were characterized by plasmid content, auxotype/serovar (A/S) class, and susceptibility to antimicrobial agents. In 1986, 95 isolates (89%) possessed the 3.2-Megadalton (MDa) beta-lactamase plasmid; 36 (34%) of these isolates also possessed the 24.5-MDa conjugative plasmid. These results contrast with those from 1984, when 37 PPNG isolates (90%) possessed the 4.4-MDa plasmid, and most possessed the 24.5-MDa conjugative plasmid. This in turn was a reversal of the pattern seen in 1983, when only 42 (69%) possessed the 3.2-MDa plasmid, and the conjugative plasmid was rare. In 1983 and 1986, isolates possessing the 4.4-MDa plasmid were more resistant to penicillin than were isolates containing the 3.2-MDa plasmid. All isolates were susceptible to spectinomycin and ceftriaxone. In early 1986, two A/S classes accounted for 66% of all isolates. Pro/IA-1,2 and Pro/IB-2 accounted for 31 (29%) and 40 (37%), respectively, and were isolated during every week in early 1986. In contrast, isolates belonging to 14 and six A/S classes possessing the 3.2- and 4.4-MDa beta-lactamase plasmid, respectively, were isolated sporadically. The composition of the PPNG strain population in Miami is dynamic, a factor that may have important implications for the use of traditional disease intervention strategies.

Disease Outbreaks↗
PubMedDate not supplied

Trends in resistance of Neisseria gonorrhoeae to antimicrobial agents in the United States.

Resistance of Neisseria gonorrhoeae to antimicrobial agents is increasing in the United States. The number of cases of gonorrhea caused by beta-lactamase-producing strains of N. gonorrhoeae (PPNG) increased for the second consecutive year, and 16,608 were reported in 1986; these accounted for greater than 1.6% of all cases of gonorrhea. PPNG is endemic in Florida, New York City, and Los Angeles, and these areas may serve as foci for spread of PPNG strains in the United States. In 1985 N. gonorrhoeae strains that exhibited high-level resistance to tetracycline (TRNG; MIC, greater than or equal to 16.0 micrograms/ml) were reported. Tetracycline resistance was due to the tetM determinant in a 25.2-MDa tetM-conjugative plasmid. The prevalence of TRNG infections was greater than 4% in at least two communities. Strains with chromosomally-mediated resistance to several antimicrobial agents have been isolated more often; 399 cases were reported during the first half of 1986. Spectinomycin-resistant strains have been isolated in several cities, and strains with decreased susceptibility to ceftriaxone have been isolated. Phenotypic characterizations of strains of N. gonorrhoeae by auxotype and serovar, plasmid content, and antibiograms have permitted more detailed study of the heterogeneity and dynamics of strain populations. Characterization of outbreaks caused by resistant strains and surveillance of regional and temporal changes in antimicrobial resistance in gonococcal strain populations may be used in design of innovative strategies for gonorrhea control and for making anticipatory changes in recommended therapies for gonorrhea.

Anti-Bacterial Agents↗