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  1. May 2017
    1. Mechanisms of Resistance to Fluoroquinolones Fluoroquinolones inhibit the replication of DNA; they are believed to bind to the GyrA region of DNA gyrase, which is attached to DNA, and inhibit the enzyme from supercoiling the DNA (37). Resistance to fluoroquinolones in N. gonorrhoeae is associated with mutations that result in amino acid changes in the A subunit (GyrA) and the B subunit (GyrB) of the DNA gyrase, and in the parC-encoded subunit of topoisomerase IV (37-40). Although mutations in gyrB confer low-level resistance to naladixic acid, high-level quinolone resistance is associated with mutations in the quinolone resistance-determining region of gyrA (41). Topoisomerase IV, encoded by parC and parE in Escherichia coli and believed to be located in the cytoplasmic membrane, is involved in DNA replication but is not as sensitive to fluoroquinolone inhibition as is DNA gyrase (37). No parE analog has been detected in N. gonorrhoeae (37). Mutations in gyrA and parC are most relevant when considering clinically significant levels of fluoroquinolone resistance in N. gonorrhoeae (37,39,40). Similar results have been obtained in studies of gyrA mutations in both laboratory-adapted strains and clinical isolates (37,39,40): ciprofloxacin-susceptible strains (MICs, <0.03 µg/ml) had no mutations in gyrA and strains with MICs, ≥0.5 µg/ml of ciprofloxacin may have changes in nucleotides 272 and 283 of gyrA. In addition, strains with MICs ≥2.0 had mutations in parC. Mutations in parC were observed only in strains with at least one mutation in gyrA (37,39) and appeared to be associated with an MIC higher than would be expected with the gyrA mutation alone (39). Mutations in gyrA and parC may be characterized by polymerase chain reaction and DNA sequencing (37,39). The transfer of gyrA and parC mutations between gonococcal strains has been demonstrated in vitro (37). The presence of transformation sequences just downstream from the gyrA sequences suggests that transformation may play a role in the spread of gyrA mutations between gonococcal strains in vivo (37). The opportunity for transformation of genes between gonococcal strains, which depends on concurrent infections with multiple strains, has been documented for women and homosexual men (42,43).
    1. Themostcommonmechanismofhigh-levelfluoroquino-loneresistanceisduetomutationinoneormoreofthegenesthatencodetheprimaryandsecondarytargetsofthesedrugs,thetypeIItopoisomerases(gyrA,gyrB,parC,andparE).TheregionwheremutationsariseinthesegenesthatencodefluoroquinoloneresistanceisashortDNAsequenceknownasthequinoloneresistance-deter-miningregion(QRDR)[28,29].MutationsintheQRDRofthesegenes,resultinginaminoacidsubstitutions,alterthetargetproteinstructureandsubsequentlythefluoroquin-olone-bindingaffinityoftheenzyme,leadingtodrugresis-tance[30,31].

      Fluoroquinolone resistance.

    1. The ribosomal protection proteins have homology to elongation factors EF-Tu and EF-G (259, 292). The greatest homology is seen at the N-terminal area, which contains the GTP-binding domain. The Tet(M), Tet(O), and OtrA proteins reduce the susceptibility of ribosomes to the action of tetracyclines. The Streptomyces Otr(A) protein has greatest overall amino acid similarity to elongation factors.

      Resistance to tetracycline

    1. Given the global nature of gonorrhea, the high rate of usage of antimicrobials, suboptimal control and monitoring of antimicrobial resistance (AMR) and treatment failures, slow update of treatment guidelines in most geographical settings, and the extraordinary capacity of the gonococci to develop and retain AMR, it is likely that the global problem of gonococcal AMR will worsen in the foreseeable future and that the severe complications of gonorrhea will emerge as a silent epidemic.

      Public health concerns

  2. bacmap.wishartlab.com bacmap.wishartlab.com
    1. Names Neisseria gonorrhoeae FA 1090 Accession numbers NC_002946 Background Neisseria gonorrhoeae is one of two pathogenic Neisseria, this species causes the sexually transmitted disease (STD) gonorrhea, which is the leading reportable STD in adults in the USA. This human-specific organism colonizes and invades the mucosal surface of the urogenital epithelium, crosses the epithelial barrier, and ends up multiplying on the basement membrane. The result is severe painful inflammation and purulent discharge. Neisseria gonorrhoeae (strain NCCP11945) was isolated in 2002 from a vaginal smear of a Korean patient. This is a multidrug-resistant strain and will be used to understand the prevalence, antibiotic resistance, and importance of horizontal gene transfer within this important, naturally competent organism. (EBI Integr8) Taxonomy Kingdom:Bacteria Phylum:Proteobacteria Class:Betaproteobacteria Order:Neisseriales Family:Neisseriaceae Genus:Neisseria Species:gonorrhoeae Strain FA 1090 Complete Yes Sequencing centre (08-APR-2002) National Center for Biotechnology Information, NIH, Bethesda, MD 20894, USA(10-MAR-2003) Microbiology and Immunology, University of Oklahoma Health Sciences Center, 975 NE 10th St., Oklahoma City, OK Sequencing quality Level 6: Finished Sequencing depth NA Sequencing method NA Isolation site Patient with disseminated gonococcal infection Isolation country NA Number of replicons 1 Gram staining properties Negative Shape Cocci Mobility No Flagellar presence No Number of membranes 2 Oxygen requirements Aerobic Optimal temperature 35.0 Temperature range Mesophilic Habitat HostAssociated Biotic relationship Free living Host name Homo sapiens Cell arrangement Pairs, Singles Sporulation Nonsporulating Metabolism NA Energy source NA Diseases Gonorrhea Pathogenicity Yes

      useful information

    1. Neisseria gonorrhoeae infections are acquired by sexual contact and usually affect the mucous membranes of the urethra in males and the endocervix and urethra in females. The pathogenic mechanism involves the attachment of the bacterium to nonciliated epithelial cells through pili (fimbriae) and the production of lipopolysaccharide endotoxin. [8]. Neisseria gonorrhoeae is only found after sexual contact with an infected person (or in the case of infections in the newbord, direct contact).

      Location and pathology

    2. he recommended procedure for isolating Neisseria gonorrhoeae involves the inoculation of a specimen directly onto a nutritive growth medium that is at room temperature and immediate incubation at 35-37ºC in an atmosphere of 3 – 10% added CO2

      Some aspects of growing conditions

    3. The organism is usually found interacellulary in polymorphonuclear leukocytes, or a specific category of white blood cells with varying shapes of nuclei, of the gonorrhea pustular exudates [8] with humans as its only natural host

      Answer to question 4: Where is the organism found normally?

    1. The catalase test (3% hydrogen peroxide) or superoxol (30% hydrogen peroxide) are other rapid tests used in the presumptive identification of N gonorrhoeae. A drop of the reagent is placed in the centre of a clean glass slide and the suspect colony is picked with a loop and emulsified in the reagent. N gonorrhoeae will produce a positive reaction with bubbling within 1 s to 2 s. Weak bubbling or bubbling after 3 s indicates a negative reaction (5) (Table ​(Table2).2).

      Catalase test

    2. The inoculated plates should be incubated at 35°C to 37°C in a moist atmosphere enriched with CO2 (3% to 7%) (5). An 18 h to 24 h culture should be used as the inoculum for additional tests. Plates should not be incubated for longer than 48 h because most old cultures would not survive storage conditions.

      Culture conditions

    1. All isolates were susceptible to penicillin, and their MICs ranged from ≤0.016 to 0.06 μg/ml. The MBCs ranged between ≤0.016 and 0.5 μg/ml, with no evidence of tolerance. Three isolates, two GGS (large-colony phenotype) and one GCS (large-colony phenotype), were resistant to erythromycin (MICs > 16 μg/ml). The range of erythromycin MICs was ≤0.016 to >16 μg/ml. All isolates were susceptible to vancomycin (MICs between 0.12 and 0.5 μg/ml). Eighteen isolates of GGS exhibited tolerance of vancomycin (MBCs 32 or more times higher than the MICs [Table 2]).

      Antibiotic resistance

    1. Presumptive diagnosis of gonorrhea is made on the basis of one of the following three criteria:typical gram-negative intracellular diplococci on microscopic examination of a smear of urethral exudate from men or endocervical secretions from women*;growth of a gram-negative, oxidase-positive diplococcus, from the urethra (men) or endocervix (women), on a selective culture medium, and demonstration of typical colonial morphology, positive oxidase reaction, and typical gram- negative morphology;detection of N. gonorrhoeae by a nonculture laboratory test (Antigen detection test (e.g., Gonozyme [Abbott]), direct specimen nucleic acid probe test (e.g., Pace II [GenProbe]), nucleic acid amplification test (e.g., LCR [Abbott]).

      tests for gonorrhea

    1. Doctors usually will treat the patient with antibiotics that are effective on the locally occurring N. gonorrhoeae strains. Currently, the CDC recommends the following treatment for gonorrhea: ceftriaxone, 250mg IM plus a single dose of azithromycin, 1 g, orally.

      Treatment

    1. Thayer-Martin agar (or Thayer-Martin medium) is a Mueller-Hinton agar with 5% chocolate sheep blood and antibiotics. It is used for culturing and primarily isolating pathogenic Neisseria bacteria, including Neisseria gonorrhoeae and Neisseria meningitidis, as the medium inhibits the growth of most other microorganisms.

      Thayer-Martin Plate

    1. FeverAbdominal painDischarge from the penis or vaginaPain with urinationArthritis, joint painAppearance of a rash with dark centersLethargyRectal pain or dischargeSore throat (pharyngitis)Sexual contact with an infected person

      Symptoms

    1. Symptoms depend on the type of STD contracted. Oral gonorrhea, as described by the Centers for Disease Control and Prevention (CDC), is also called pharyngeal gonorrhea because it typically affects the pharynx. Symptoms that could indicate an oral STD include: Sores in the mouth, which may be painless. Lesions similar to cold sores and fever blisters around the mouth. Red, painful throat and difficulty swallowing. Tonsillitis. Redness with white spots resembling strep throat. Whitish or yellow discharge.

      Symptoms of oral infection

    1. Gonococcal culture has low sensitivity (<50%) for detecting oropharyngeal gonorrhoea, and, although not yet approved commercially, nucleic acid amplification tests (NAAT) are the assay of choice.

      culture has low sensitivity so NAAT tests are preferred

    1. Microbiologyand PathologyoEtiologic agent is Neisseria gonorrhoeae.oGram-negative intracellular diplococcus, oxidase-positive, utilizes glucose, but not sucrose, maltose, or lactose. Infects mucus-secreting epithelial cells.oDivides by binary fission every 20-30 minutes.oN. gonorrhoeaeattachesto different types of mucus-secreting epithelial cells via a number of structures located on the surface of gonococci.oN. gonorrhoeaehas ability to alter these surface structures, which helps the organism evade an effective host response.oN. gonorrhoeaeemploys several mechanisms to disarm the complement system, which may result in a survival advantage in the humanhost.

      gonorrhoeae pathogenesis

    1. Gonococcal specimens should be subcultured from the selective primary medium to a noninhibitory medium, e.g., chocolate agar with 1% IsoVitaleX to obtain a pure culture of the specimen. If the subcultured specimen is not pure, serial subcultures of individual colonies must be performed until a pure culture is obtained. After 18 to 20 hrs. incubation, a heavy suspension of growth from the pure culture should be made in trypticase soy broth containing 20% (v/v) glycerol

      how to get pure sample

    2. A presumptive identification of N. gonorrhoeae will be based on the following criteria: (i) growth of typical appearing colonies on a selective medium such as Thayer-Martin at 35oC to 36.5oC in 5% CO2, (ii) a positive oxidase test, and (iii) the observation of gram-negative, oxidase-positive diplococci in stained smears.

      how to test for n. gonorrhoeae