Antibiotic resistant N. gonorrhoeae in Trinidad and Tobago.

We tested the susceptibility patterns of 128 N. gonorrhoeae isolates to six antimicrobials; penicillin, tetracycline, spectinomycin, ceftriaxone, ciprofloxacin and azithromycin, and examined whether certain demographic or behavioral factors related to antibiotic use increased the likelihood of infection by a resistant strain. There was a low rate of resistance to penicillin; penicillinase-producing and chromosomal-mediated penicillin resistant gonorrhea were estimated to be 0.8%. A much higher proportion of isolates were resistant to tetracycline (up to 15%). All isolates were sensitive to spectinomycin, ciprofloxacin and ceftriaxone. However, less than 2% of isolates displayed intermediate resistance to both ciprofloxacin and ceftriaxone, and 9% exhibited intermediate resistance to spectinomycin. Patients who had obtained medication before attending the clinic and had taken all of the medication were more likely (p = 0.03) to be infected with a resistant strain of gonococcus. Also, patients who were asked by a clinic doctor to return for a test of cure during an earlier clinic visit, but who did not return were more likely to be infected with a resistant organism (p = 0.006) compared to those who returned at the doctor's request. These findings have important implications for antibiotic use and educational programs in Trinidad and Tobago.     

Clustering of Marine Bacteria in Seawater Enrichments

Seawater enrichments of marine bacteria clustered in 20- to 50-(mu)m-wide bands near air-water interfaces. The cells within the band travelled at up to 212 (mu)m s(sup-1) and at an average speed of 163 (mu)m s(sup-1). Mean cell speeds peaked mid-run at 187 (mu)m s(sup-1). At the end of the run, bacteria reversed direction rather than randomly reorienting. The duration of the stops during reversal was estimated at 18 ms, six to seven times shorter than that found in enteric bacteria. Cells hundreds of micrometers from the band travelled at half the speed of the bacteria in the band. The fastest isolate from the seawater enrichment was identified as Shewanella putrefaciens and had an average speed of 100 (mu)m s(sup-1) in culture. Air-water interfaces produced no clustering or speed changes in isolates derived from enrichments. Salinity and pH, however, both influenced speed. The speed and reversal times of the seawater enrichments indicate that the bacteria in them are better adapted for clustering around small point sources of nutrients than are either enteric or cultured marine bacteria.     

Role of chromosomal rearrangement in N. gonorrhoeae pilus phase variation

N. gonorrhoeae undergoes pilus phase and antigenic variation. During phase variation, the pilin gene is turned on and off at high frequencies. Two loci on the gonococcal chromosome from strain MS11 function as expression sites for the pilin gene (pilE1 and pilE2); many other sites apparently contain silent variant pilin sequences. We reported previously that during pilus phase variation, when cells switch from the pilus expressing state (P+) to the nonexpressing state (P-), genome rearrangement occurs. We have examined phase variation in more detail, and we report that in most P+ to P- switches a deletion of pilin gene information occurs in one or both expression sites. This deletion is due to either a simple or a multiple-step recombination event involving directly repeated sequences in the expression loci. The deletion explains the state of some P- cells, but not all. In the latter cells pilin expression is probably controlled by an undefined regulator.     

N. elongata produces type IV pili that mediate interspecies gene transfer with N. gonorrhoeae

The genus Neisseria contains at least eight commensal and two pathogenic species. According to the Neisseria phylogenetic tree, commensals are basal to the pathogens. N. elongata, which is at the opposite end of the tree from N. gonorrhoeae, has been observed to be fimbriated, and these fimbriae are correlated with genetic competence in this organism. We tested the hypothesis that the fimbriae of N. elongata are Type IV pili (Tfp), and that Tfp functions in genetic competence. We provide evidence that the N. elongata fimbriae are indeed Tfp. Tfp, as well as the DNA Uptake Sequence (DUS), greatly enhance N. elongata DNA transformation. Tfp allows N. elongata to make intimate contact with N. gonorrhoeae and to mediate the transfer of antibiotic resistance markers between these two species. We conclude that Tfp functional for genetic competence is a trait of a commensal member of the Neisseria genus. Our findings provide a mechanism for the horizontal gene transfer that has been observed among Neisseria species.     

Biological and chemical characteristics of allergen preparations from Neisseria (N. meningitidis, N. gonorrhoeae, N. perflava)]

Various methods of isolating allergen fractions from N. meningitidis, N. gonorrhoeae and N. perflava were tested. The biological activity of the preparation was found to depend on the method of its production, which determined its chemical composition. When gonococcal and meningococcal allergens and N. perflava allergen were used in skin tests, cross reactions were observed. Nevertheless, as the intensity and size of skin reaction was much greater when a homologous preparation was administered, it was possible to differentiate the presence of sensitization to a definite microbial species. Electrophoresis in acrylamide gel revealed the heterogeneity of allergen preparations. The ability of the preparation to induce skin reaction was not connected with its serological properties.     

Ultrastructure of Thiothrix spp. and Type 021N Bacteria

The ultrastructural features of two groups of filamentous sulfur bacteria, Thiothrix spp. and an unnamed organism designated type 021N, were examined by transmission electron microscopy. Negative staining of whole cells and filaments with uranyl acetate revealed the presence of tufts of fimbriae located at the ends of individual gonidia of Thiothrix sp. strain A1 and type 021N strain N7. Holdfast material present at the center of mature rosettes was observed in thin sections stained with ruthenium red. A clearly defined sheath enveloped the trichomes of two of three Thiothrix strains but was absent from type 021N filaments. The outer cell wall appeared more complex in type 021N strains than in Thiothrix isolates. Bulbs or clusters of irregularly shaped cells, often present in filaments of type 021N bacteria, appeared to result from crosswalls which formed at angles oblique to the filament axis. The multicellular nature of these sulfur bacteria was apparent in that only the cytoplasmic membrane and peptidoglycan layer of the cell wall were involved in the septation process. Sulfur inclusions which developed in the presence of sodium thiosulfate were enclosed by a single-layered envelope and located within invaginations of the cytoplasmic membrane.     

Autolysis of Neisseria gonorrhoeae.

Physiological conditions that would provide maximal rates of autolysis of Neisseria gonorrhoeae were examined. Autolysis was found to occur over a broad pH range with the optimum at pH 9.0 IN 0.05 M tris(hydroxymethyl)amino-methane-maleate buffer. The temperature optimum was found to be 40 C. Potassium ions greatly stimulated autolysis at a concentration of 0.01 M. Exposure of growing N. gonorrhoeae cells to penicillin, vancomycin, or D-cycloserine influenced the susceptibility to the autolysis, whereas chloramphenicol afforded some protection against autolysis. The primary structure of the peptidoglycan is composed of muramic acid/glutamic acid/alanine/diaminopimelic acid/glucosamine in approximate molar ratios of 1:1:2:1:1, respectively. Exogenous radioactive diaminopimelic acid, D-glucosamine, and D-alanine were incorporated into peptidoglycan. During autolysis these radioactive fragments were released from cells.     

Autolysis of Neisseria gonorrhoeae.

Autolysis of Neisseria gonorrhoeae was studied under different conditions. It was found that low pH and temperature, as well as the presence of divalent cations, spermine, sucrose, and polyvinylpyrrolidone, stabilized nongrowing gonococci. Ethylenediaminetetraacetic acid alone promoted lysis, whereas lysozyme had only a limited additive effect. The autolytic behavior of gonococci appears to be connected with their prolonged cell division process. The relative dependence on the outer membrane and the peptidoglycan layer for the mechanical stability of gonococci is discussed.     

The N. gonorrhoeae type IV pilus stimulates mechanosensitive pathways and cytoprotection through a pilT-dependent mechanism

The Neisseria gonorrhoeae type IV pilus is a retractile appendage that can generate forces near 100 pN. We tested the hypothesis that type IV pilus retraction influences epithelial cell gene expression by exerting tension on the host membrane. Wild-type and retraction-defective bacteria altered the expression of an identical set of epithelial cell genes during attachment. Interestingly, pilus retraction, per se, did not regulate novel gene expression but, rather, enhanced the expression of a subset of the infection-regulated genes. This is accomplished through mitogen-activated protein kinase activation and at least one other undefined stress-activated pathway. These results can be reproduced by applying artificial force on the epithelial membrane, using a magnet and magnetic beads. Importantly, this retraction-mediated signaling increases the ability of the cell to withstand apoptotic signals triggered by infection. We conclude that pilus retraction stimulates mechanosensitive pathways that enhance the expression of stress-responsive genes and activate cytoprotective signaling. A model for the role of pilus retraction in influencing host cell survival is presented.     

Predominant Catalase-negative Soil Bacteria. II. Occurrence and Characterization of Actinomyces humiferus, sp. N

A microorganism resembling an Actinomyces species was found to be a numerically predominant inhabitant of various organically rich soils. This organism forms a hyphal-like structure with true branching that fragments into gram-positive diphtheroid and coccoid elements. Its cells ferment carbohydrates and contain both lysine and ornithine as the major basic amino acids of the cell wall. It is catalase-negative, microaerophilic to aerobic, and sensitive to lysozyme, and it is dependent on an organic nitrogen source and incubation at 30 C for optimum growth. Based on these characteristics, a new species, Actinomyces humiferus, is proposed. The ecological and medical implications of a large soil population of this microorganism are discussed.     

Temperature-sensitive mutants of Neisseria gonorrhoeae.

Nine temperature-sensitive (Ts) mutants of Neisseria gonorrhoeae strain 49191 were isolated. They were proven to be different from each other by results of transformation experiments. None of the Ts mutations appeared to be linked to antibiotic resistance genes from strain 24392. However, Ts-9 demonstrated 8% linkage with a nalidixic acid resistance marker from strain RW-2.     

Autoplaquing in Neisseria gonorrhoeae.

Irregularly shaped autoplaques were observed on a lawn of two different strains of Neisseria gonorrhoeae. Autoplaquing occurred on gonococcal genetic medium lacking arginine and was noninducible on complete gonococcal genetic medium. The cell density, incubation temperature, and agar base influenced autoplaquing. Single-colony suspensions varied in plaque morphology. We were unable to isolate a stable nonplaquing variant but separated strain RUN5287 into two plaquing phenotypes.     

光合细菌N9281生物学特性及其应用

从黑龙江省同江水稻根际土壤中分离得到光合细菌N9281菌株,经系统细菌学鉴定定名为球形红假单孢菌(Rhodop-seudomonas sphaeroides)。该菌菌体呈卵球形或球形,革兰氏梁包呈阴性,无芽孢,能较好利用H2S,对碳、氮源利用广泛,在厌氧光照条件下培养72h,菌数达到30亿个活菌／mL．在农业生产中,以2L／亩剂量接种,田问试验结果表明：可使波菜增产20.8％;果实类蔬菜增产12．5—13．6％：水稻增产10．4％;人参增产22．03％;出红参率增加6．5％,并减轻人参锈病发病率,防治效果达到61．3％。     

Conjugative plasmids in Neisseria gonorrhoeae.

A conjugation system initially discovered in beta-lactamase-producing gonococci mobilized small non-selftransmissible R plasmids encoding beta-lactamase (penicillinase) production into other gonococci, Neisseria, and Escherichia coli. This conjugation system was mediated by a separate selftransmissible plasmid of 23.9 X 10(6) daltons, pFA2. Conjugative plasmids capable of mobilizing R plasmids were also found in nearly 8% of the non-penicillinase-producing gonococci. These were similar to pFA2 in size, buoyant density, and restriction endonuclease digest patterns but were less efficient than pFA2 in mobilization of the penicillinase plasmid pFA3. The presence of conjugative plasmids in gonococci isolated before the appearance of penicillinase-producing strains indicates that a conjugation system for plasmid transfer predated the appearance of R plasmids in gonococci.     

Penicillinase-producing Neisseria gonorrhoeae in Canada.

The incidence of infection with penicillinase-producing Neisseria gonorrhoeae (PPNG) reported to the Laboratory Centre for Disease Control in Ottawa has steadily increased since the first Canadian isolation of such a strain in 1976. As of September 1980 a total of 66 PPNG isolates had been referred for biological and genetic characterization as well as for central documentation of the epidemiologic aspects of each case. Over 90% of the infections were firmly traced to patients or contacts who had acquired the infection abroad; this indicates that Canada does not, as yet, have an epidemic focus of PPNG infection. This report includes a synopsis of the biological characteristics of these isolates and an analysis of the results of primary antibiotic treatment that illustrates the importance of considering spectinomycin as the antibiotic of choice for PPNG infections.     

Susceptibility of N. gonorrhoeae to Antibiotics: A Study of 200 Consecutive Strains Isolated in Winnipeg in 1962

Gonorrhea has increased in incidence over the past five years in Manitoba as elsewhere. Cases which did not respond to routine penicillin treatment were noted to be occuring more often. In 1948, strains of N. gonorrhoeae isolated in Canada were all sensitive to 0.06 unit of penicillin per c.c. in vitro. Commencing in May 1962, strains of N. gonorrhoeae were isolated from 100 patients of each sex attending the clinic at the St. Boniface General Hospital. Eighteen per cent required concentrations of more than 0.05 unit of penicillin per ml. to inhibit growth; 31% were not inhibited by the 2 μg. disc of dihydrostreptomycin; but only one strain was found resistant to sulfisoxazole and none to oxytetracycline. Results of penicillin treatment were markedly less successful in the patients with strains that demonstrated reduced penicillin sensitivity. Use of streptomycin and a sulfonamide proved to be a satisfactory substitute. Intramuscular oxytetracycline was less successful despite the laboratory findings.     

Mechanism of autolysis of Neisseria gonorrhoeae.

The major autolysin(s) of Neisseria gonorrhoeae was solubilized from envelopes by extraction with 2% Triton X-100 containing 0.5 M NaCl. Neither Triton X-100 nor NaCl alone could effectively release the autolysin(s). The major autolysin is N-acetylmuramyl-L-alanine amidase (EC 3.5.1.28). The pH optimum for this reaction was broad, ranging from 5.5 to 8.5. Optimal hydrolysis of peptidoglycan occurred in 2% Triton X-100 in 0.1 M KCl. Attempts to purify the autolysin were unsuccessful. A rapid assay for enzyme activity was developed using radioactive cell walls as a substrate ([3H]diaminopimelic acid).