Use of viability PCR for detection of live Chlamydia trachomatis in clinical specimens

BackgroundThe current testing approach to diagnose Chlamydia trachomatis (CT) infection relies on nucleic acid amplification tests (NAATs). These tests are highly sensitive, but do not distinguish between active infection and residual bacterial nucleic acid which may remain after resolution of infection, or via cross-contamination. Better methods to assess the viability of CT detected in clinical samples would be useful in determining the relevance of CT detection in a variety of clinical settings. The goal of this study was to test viability PCR (vPCR) as a method to distinguish viable bacteria from non-viable CT.MethodsThe vPCR relies on a propidium monoazide dye (PMAxx), which intercalates into accessible DNA from dead organisms and prevents their detection in a PCR assay for the CT ompA gene. We used digital PCR to quantify absolute genome copy numbers from samples. We validated the vPCR approach using laboratory stocks of CT with known viability. Then, we tested total DNA, viable CT DNA, and culture results from 18 clinical vaginal specimens and 25 rectal clinical specimens, all of which had tested positive by NAAT.ResultsIn laboratory stocks of CT, vPCR using defined ratios of heat-killed to live bacteria tracked closely with expected results. In vaginal clinical specimens, vPCR and total DNA results were correlated, though total DNA genomes outnumbered viable genomes by 2.2–52.6-fold more copies. As expected, vPCR detected more total genomes than culture results. Both vPCR and total DNA correlated with culture results (Spearman correlation R = 0.8425 for total DNA and 0.8056 for vPCR). Ten rectal NAAT positive specimens were negative by total DNA PCR, vPCR, and were negative or inconclusive by culture. Of the 6 rectal specimens that were culture positive, all were total DNA and vPCR positive. vPCR additionally detected viable bacterial DNA in 8 specimens which were NAAT + and culture negative, though levels were very low (mean 1,357 copies/ml)ConclusionsvPCR is a fast and easy method to assess viability in clinical specimens and is more correlated with culture results than total DNA PCR. Inconsistent ratios between total DNA and vPCR results suggest that the amount of dead bacteria varies considerably in clinical specimens. Results from rectal specimens suggest that many NAAT positive specimens do not in fact represent live replicating bacteria, and likely result in significant overuse of unnecessary antibiotics

Utility of EC 3MTM PetrifilmTM and sanitary surveys for source water assessment in Nyabushozi County, south-western Uganda

The majority of people in developing nations rely on untreated or minimally treated surface and shallow groundwater sources which are prone to faecal contamination. This study evaluated the utility of EC 3M™ Petrifilm™ and sanitary inspection forms (SIFs) as tools to assess 47 water sources and identify hazards of contamination in two rural Ugandan villages (90% were surface sources). Water samples were cultured on EC 3MTM PetrifilmTM, which are intended for the enumeration of E. coli and total coliforms following 24 h incubation at 37ºC. Isolated bacteria were cultured on MacConkey agar and identified using standard biochemical tests, while selected isolates were verified by sequencing 16S rRNA genes. From 105 Petrifilms, 110 presumptive E. coli were isolated and identified to genus level. However, only 33 presumptive E. coli isolates from 14 water sources (representing 27 distinct strains as determined by PFGE) were confirmed E. coli. The other presumptive E. coli isolates were identified as Citrobacter, Enterobacter, Proteus, Salmonella and Yersinia species. SIFs used an adapted survey designed for urban water sources of Uganda. The form yielded an SIF score based on binary data and characterized potential sources of contamination. SIF scores alone offered little information to distinguish between contamination levels of surface water sources, but the information collected in the surveys could be used to identify ways to improve sources. The results of this study suggest that the use of sanitary surveys may assist in identifying potential pollution sources that may be targeted to protect water sources. Bacterial monitoring using EC 3MTM PetrifilmsTM may be effective for the screening of relative levels of contamination of source waters, including surface sources.Keywords: drinking water, developing countries, sanitary survey, EC 3MTM PetrifilmT

Surfactant-enhanced DNA accessibility to nuclease accelerates phenotypic β-lactam antibiotic susceptibility testing of Neisseria gonorrhoeae

Rapid antibiotic susceptibility testing (AST) for Neisseria gonorrhoeae (Ng) is critically needed to counter widespread antibiotic resistance. Detection of nucleic acids in genotypic AST can be rapid, but it has not been successful for β-lactams (the largest antibiotic class used to treat Ng). Rapid phenotypic AST for Ng is challenged by the pathogen’s slow doubling time and the lack of methods to quickly quantify the pathogen’s response to β-lactams. Here, we asked two questions: (1) Is it possible to use nucleic acid quantification to measure the β-lactam susceptibility phenotype of Ng very rapidly, using antibiotic-exposure times much shorter than the 1- to 2-h doubling time of Ng? (2) Would such short-term antibiotic exposures predict the antibiotic resistance profile of Ng measured by plate growth assays over multiple days? To answer these questions, we devised an innovative approach for performing a rapid phenotypic AST that measures DNA accessibility to exogenous nucleases after exposure to β-lactams (termed nuclease-accessibility AST [nuc-aAST]). We showed that DNA in antibiotic-susceptible cells has increased accessibility upon exposure to β-lactams and that a judiciously chosen surfactant permeabilized the outer membrane and enhanced this effect. We tested penicillin, cefixime, and ceftriaxone and found good agreement between the results of the nuc-aAST after 15–30 min of antibiotic exposure and the results of the gold-standard culture-based AST measured over days. These results provide a new pathway toward developing a critically needed phenotypic AST for Ng and additional global-health threats

Mycoplasma genitalium in the US (MyGeniUS): Surveillance data from sexual health clinics in 4 US regions

BACKGROUND: Mycoplasma genitalium (MG) is on the CDC Watch List of Antimicrobial Resistance Threats, yet there is no systematic surveillance to monitor change. METHODS: We initiated surveillance in sexual health clinics in 6 cities, selecting a quota sample of urogenital specimens tested for gonorrhea and/or chlamydia. We abstracted patient data from medical records and detected MG and macrolide-resistance mutations (MRMs) by nucleic acid amplification testing. We used Poisson regression to estimate adjusted prevalence ratios (aPRs) and 95% CIs, adjusting for sampling criteria (site, birth sex, symptom status). RESULTS: From October-December 2020 we tested 1743 urogenital specimens: 57.0% from males, 46.1% from non-Hispanic Black persons, and 43.8% from symptomatic patients. MG prevalence was 16.6% (95% CI: 14.9-18.5%; site-specific range: 9.9-23.5%) and higher in St Louis (aPR: 1.9; 1.27-2.85), Greensboro (aPR: 1.8; 1.18-2.79), and Denver (aPR: 1.7; 1.12-2.44) than Seattle. Prevalence was highest in persons \u3c18 years (30.4%) and declined 3% per each additional year of age (aPR: .97; .955-.982). MG was detected in 26.8%, 21.1%, 11.8%, and 15.4% of urethritis, vaginitis, cervicitis, and pelvic inflammatory disease (PID), respectively. It was present in 9% of asymptomatic males and 15.4% of asymptomatic females, and associated with male urethritis (aPR: 1.7; 1.22-2.50) and chlamydia (aPR: 1.7; 1.13-2.53). MRM prevalence was 59.1% (95% CI: 53.1-64.8%; site-specific range: 51.3-70.6%). MRMs were associated with vaginitis (aPR: 1.8; 1.14-2.85), cervicitis (aPR: 3.5; 1.69-7.30), and PID cervicitis (aPR: 1.8; 1.09-3.08). CONCLUSIONS: MG infection is common in persons at high risk of sexually transmitted infections; testing symptomatic patients would facilitate appropriate therapy. Macrolide resistance is high and azithromycin should not be used without resistance testing

Proteomics-driven Antigen Discovery for Development of Vaccines Against Gonorrhea

Expanding efforts to develop preventive gonorrhea vaccines is critical because of the dire possibility of untreatable gonococcal infections. Reverse vaccinology, which includes genome and proteome mining, has proven very successful in the discovery of vaccine candidates against many pathogenic bacteria. However, progress with this approach for a gonorrhea vaccine remains in its infancy. Accordingly, we applied a comprehensive proteomic platform—isobaric tagging for absolute quantification coupled with two-dimensional liquid chromatography and mass spectrometry—to identify potential gonococcal vaccine antigens. Our previous analyses focused on cell envelopes and naturally released membrane vesicles derived from four different Neisseria gonorrhoeae strains. Here, we extended these studies to identify cell envelope proteins of N. gonorrhoeae that are ubiquitously expressed and specifically induced by physiologically relevant environmental stimuli: oxygen availability, iron deprivation, and the presence of human serum. Together, these studies enabled the identification of numerous potential gonorrhea vaccine targets. Initial characterization of five novel vaccine candidate antigens that were ubiquitously expressed under these different growth conditions demonstrated that homologs of BamA (NGO1801), LptD (NGO1715), and TamA (NGO1956), and two uncharacterized proteins, NGO2054 and NGO2139, were surface exposed, secreted via naturally released membrane vesicles, and elicited bactericidal antibodies that cross-reacted with a panel of temporally and geographically diverse isolates. In addition, analysis of polymorphisms at the nucleotide and amino acid levels showed that these vaccine candidates are highly conserved among N. gonorrhoeae strains. Finally, depletion of BamA caused a loss of N. gonorrhoeae viability, suggesting it may be an essential target. Together, our data strongly support the use of proteomics-driven discovery of potential vaccine targets as a sound approach for identifying promising gonococcal antigens.This is the publisher’s final pdf. The published article is copyrighted by The American Society for Biochemistry and Molecular Biology and can be found at: http://www.mcponline.org/content/15/7/233

Molecular identification of CTX-M and blaOXY/K1 β-lactamase genes in Enterobacteriaceae by sequencing of universal M13-sequence tagged PCR-amplicons

<p>Abstract</p> <p>Background</p> <p>Plasmid encoded ^<it>bla</it>CTX-M enzymes represent an important sub-group of class A β-lactamases causing the ESBL phenotype which is increasingly found in <it>Enterobacteriaceae </it>including <it>Klebsiella </it>spp. Molecular typing of clinical ESBL-isolates has become more and more important for prevention of the dissemination of ESBL-producers among nosocomial environment.</p> <p>Methods</p> <p>Multiple displacement amplified DNA derived from 20 <it>K. pneumoniae </it>and 34 <it>K. oxytoca </it>clinical isolates with an ESBL-phenotype was used in a universal CTX-M PCR amplification assay. Identification and differentiation of ^<it>bla</it>CTX-M and ^<it>bla</it>OXY/K1 sequences was obtained by DNA sequencing of M13-sequence-tagged CTX-M PCR-amplicons using a M13-specific sequencing primer.</p> <p>Results</p> <p>Nine out of 20 <it>K. pneumoniae </it>clinical isolates had a ^<it>bla</it>CTX-M genotype. Interestingly, we found that the universal degenerated primers also amplified the chromosomally located K1-gene in all 34 <it>K. oxytoca </it>clinical isolates. Molecular identification and differentiation between ^<it>bla</it>CTX-M and ^<it>bla</it>OXY/K1-genes could only been achieved by sequencing of the PCR-amplicons. <it>In silico </it>analysis revealed that the universal degenerated CTX-M primer-pair used here might also amplify the chromosomally located ^<it>bla</it>OXY and K1-genes in <it>Klebsiella </it>spp. and K1-like genes in other <it>Enterobacteriaceae</it>.</p> <p>Conclusion</p> <p>The PCR-based molecular typing method described here enables a rapid and reliable molecular identification of ^<it>bla</it>CTX-M, and ^<it>bla</it>OXY/K1-genes. The principles used in this study could also be applied to any situation in which antimicrobial resistance genes would need to be sequenced.</p

Self-medication with antibiotics for the treatment of menstrual symptoms in southwest Nigeria: a cross-sectional study

Background: Self-medication with antibiotics is an important factor contributing to the development of bacterial antibiotic resistance. The purpose of this study was to evaluate the prevalence of self-medication with antibiotics for the treatment of menstrual symptoms among university women in Southwest Nigeria. Methods: A cross-sectional survey was administered to female undergraduate and graduate students (n = 706) at four universities in Southwest Nigeria in 2008. The universities were selected by convenience and the study samples within each university were randomly selected cluster samples. The survey was self-administered and included questions pertaining to menstrual symptoms, analgesic and antibiotic use patterns, and demographics. Data were analyzed using descriptive statistics and logistic regression. Results: The response rate was 95.4%. Eighty-six percent (95% CI: 83-88%) of participants experienced menstrual symptoms, and 39% (95% CI: 36-43%) reported using analgesics to treat them. Overall, 24% (95% CI: 21-27%) of participants reported self-medicated use of antibiotics to treat the following menstrual symptoms: cramps, bloating, heavy bleeding, headaches, pimples/acne, moodiness, tender breasts, backache, joint and muscle pain. Factors associated with this usage were: lower levels of education (Odds Ratio (OR): 2.8, 95% CI: 1.1-7.1, p-value: 0.03); nonscience major (OR: 1.58, 95% CI: 1.03-2.50, p-value: 0.04); usage of analgesics (OR: 3.17, 95% CI: 2.07-4.86, p-value: <0.001); and mild to extreme heavy bleeding (OR: 1.64, 95% CI: 1.01-2.67, p-value: 0.05) and pimples/acne (OR: 1.57, 95% CI: 0.98-2.54, p-value: 0.06). Ampicillin, tetracycline, ciprofloxacin and metronidazole were used to treat the most symptoms. Doctors or nurses (6%, 95% CI: 4-7%), friends (6%, 95% CI: 4-7%) and family members (7%, 95% CI: 5-8%) were most likely to recommend the use of antibiotics for menstrual symptoms, while these drugs were most often obtained from local chemists or pharmacists (10.2%, 95% CI: 8-12%). Conclusions: This is the first formal study to report that approximately 1 out of 4 university women surveyed in Southwest Nigeria self-medicate with antibiotics to treat menstrual symptoms. This practice could provide monthly, low-dose exposures to antibiotics among users. Further studies are necessary to evaluate the impacts of selfmedication on student health

Pulse Charging of Nickel Cadmium Batteries for Lost Capacity Recovery

Abstract: This study presents an experimental investigation on the effectiveness of pulse recharging technique in recovering the lost capacity of nickel cadmium batteries (NiCad), through a comparison test with the conventional constant-current recharging technique. Scanning Electron Microscope (SEM) analysis has been carried out on the electrodes of both pulse recharged and conventionally recharged NiCad cells after a controlled experimental process to restore the lost capacity due to shallow cycling. The results show that the pulse recharging technique performed equally well with the conventional recharging method in improving the topologies of the cell electrodes and recovering the lost capacity of the NiCad cells. The causes of capacity loss in NiCad batteries have also been investigated and the results obtained established the claim that shallow cycling enhances large and dendritic crystalline growth on the cell electrodes