Johan H Melendez

Johns Hopkins University, Baltimore, Maryland, United States

Are you Johan H Melendez?

Claim your profile

Publications (26)74.49 Total impact

  • AIDS research and human retroviruses. 10/2014; 30 Suppl 1:A172.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Adolescents may use condoms inconsistently or incorrectly, or may over-report condom use. This study used a semen exposure biomarker to evaluate the accuracy of female adolescents' reports of condom use and predict subsequent pregnancy. The sample comprised 715 sexually active African-American female adolescents, ages 15-21 years. At baseline, 6 months and 12 months, participants completed a 40-min interview and were tested for semen Y-chromosome with PCR from a self-administered vaginal swab. We predicted pregnancy from semen exposure under-report using multivariate regression controlling for oral contraception, reported condom use and coital frequency. At the 3 surveys, 30%, 20% and 15% of adolescents who reported always using condoms tested positive for semen exposure. At 6 month follow-up, 20.4% and 16.2% of the adolescents who under-reported semen exposure reported pregnancy, a higher pregnancy rate than accurate reporters of semen exposure, even accurate reporters who reported never using condoms (14.2% and 11.8%). Under-reporters of semen exposure were 3.23 (95% CI (1.61, 6.45)) times as likely to become pregnant at 6-month follow-up and 2.21 (0.94, 5.20) times as likely to become pregnant at 12-month follow-up as accurate reporters who reported not using contraception, adjusting for self-reported coital frequency. Adolescents who under-report semen exposure may be at uniquely high risk for unplanned pregnancy and STIs, and may also under-report coital frequency. Condom efficacy trials that rely on self-report may yield inaccurate results. Adapted to a clinical setting, the Y-chromosome PCR could alert women to incorrect or inconsistent condom use.
    Sexually transmitted infections 03/2014; · 2.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectives There is currently no information on whether products evaluated in HIV microbicide trials affect the detection of the semen biomarkers PSA or Y chromosome DNA. Study Design We tested (in vitro) dilutions of tenofovir (TFV), UC781, and the hydroxyethylcellulose (HEC) placebo gels using the Abacus ABAcard and the quantitative (Abbott Architect total PSA) assays for PSA and Y chromosome DNA by real-time polymerase chain reaction (real-time PCR). Results TFV gel and the HEC placebo adversely affected PSA detection using the ABAcard, but not the Abbott Architect total PSA assay. UC781 adversely affected both the ABAcard and Abbott Architect total PSA assays. While there were some quantitative changes in the magnitude of the signal, none of the products affected positivity of the Y chromosome assay. Conclusions The presence of TFV or HEC gels did not affect quantitative PSA or Y chromosome detection in vitro. Confirmation of these findings is recommended using specimens obtained following use of these gels in vivo. Implications Researchers should consider the potential for specific microbicides or any products to affect the particular assay used for semen biomarker detection. The ABAcard assay for PSA detection should not be used with TFV and HEC.
    Contraception 01/2014; · 3.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although biological markers of women's exposure to semen from vaginal intercourse have been developed as surrogates for risk of infection or probability of pregnancy, data on their persistence time and clearance are limited. During 2006-2008, 52 couples were enrolled for three 14-day cycles of abstinence from vaginal sex during which women were exposed in the clinic to a specific quantity (10, 100 or 1000 μL) of their partner's semen. Vaginal swabs were collected before and at 1, 6, 12, 24, 48, 72 and 144 h after exposure for testing for prostate-specific antigen (PSA) and Y-chromosome DNA (Yc DNA). Immediately after exposure to 1000 μL of semen, the predicted sensitivity of being PSA positive was 0.96; this decreased to 0.65, 0.44, 0.21 and 0.07 at 6, 12, 24 and 48 h, respectively. Corresponding predicted sensitivity of being Yc DNA positive was 0.72 immediately postexposure; this increased to 0.76 at 1 h postexposure and then decreased to 0.60 (at 6 h), 0.63 (at 12 h), 0.49 (at 24 h), 0.21 (at 48 h), 0.17 (at 72 h) and 0.12 (at 144 h). Overall findings suggest that PSA may be more consistent as a marker of very recent exposure and that Yc DNA is more likely to be detected in the vagina after 12 h postexposure compared to PSA.
    Contraception 08/2013; · 3.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectives Little is known about the effects of commonly used lubricants on detection of biomarkers of semen exposure. We investigated the in vitro effect of Gynol®, K-Y Jelly®, Replens®, Astroglide®, Carbopol, and Silicorel on quantitative detection of Prostate Specific Antigen (PSA). Study Design A predetermined concentration of each of the gels was added to serially diluted semen samples. Additionally, serial dilutions of each of the gels were added to three different semen dilutions (high, medium, or low). The resulting samples were tested for PSA on the Abbott ARCHITECT System. Results When using the Abbott Architect system, the only products that inhibited PSA detection were Gynol® and Replens®. The inhibition caused by Gynol® was dose-dependent, but that of Replens was dose-independent. K-Y Jelly®-spiked samples had higher PSA values than controls. Conclusions Caution is warranted when using the Abbott quantitative assay for PSA detection as a biomarker of semen exposure in settings where Gynol®, Replens® or K-Y Jelly® might also have been used. Neither Astroglide® nor Silicorel inhibited PSA detection. Additional studies evaluating other vaginal products, including microbicides, and their effects on other assays, are needed. In vivo studies will be especially important to optimize PSA detection from clinical samples. Implications Researchers should consider the potential for specific lubricants or any vaginal products to affect the particular assay used for semen biomarker detection. The Abbott Architect’s Total PSA assay should not be used with the product Replens. Caution is warranted when using the assay in settings where Gynol or K–Y jelly may have been used.
    Contraception 01/2013; · 3.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Prostate-specific antigen (PSA) is a biomarker of recent semen exposure. There is currently only limited information on whether topical vaginal products affect PSA assays. We investigated this question using various dilutions of several vaginal products (lubricants and spermicides) and the Abacus ABAcard for PSA detection. STUDY DESIGN: Pooled semen controls and various dilutions of nonoxynol-9 (N9), carboxymethyl cellulose (CMC), Replens, Gynol 2, K-Y jelly, Astroglide, Surgilube, combined with pooled semen dilutions, were tested for PSA using the Abacus ABAcard. RESULTS: N9 (2% with saline) and CMC did not appear to affect the results of testing with the ABAcard, but not all semen dilutions were tested. The other products (including Replens and Gynol, which is 2% N9 with propylene glycol, K-Y, Astroglide and Surgilube) at some of the dilutions tested either affected or gave invalid results with PSA testing using the ABAcard. Both Gynol 2 and K-Y at 1:10 dilution gave false-positive results. CONCLUSIONS: Some vaginal products affect PSA results obtained by using the semiquantitative ABAcard. In vivo confirmation is necessary to further optimize PSA detection when topical vaginal products are present.
    Contraception 12/2012; · 3.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Neisseria gonorrhoeae lipooligosaccharides (LOSs) induce immunoglobulin G that protects men from experimental infection. This raises the possibility that an LOS vaccine might prevent gonorrhea. Gonococci make different LOS molecules, depending on whether 3 genes, lgtA, lgtC, and lgtD, are in frame (IF) or out of frame (OOF). Mispairing of polymeric guanine (polyG) tracts within each gene determines its frame during replication. We amplified lgtA, lgtC, and lgtD from diagnostic slides of urethral exudates and sequenced their polyG tracts. We found that lgtA in exudative bacteria is IF and that lgtC is OOF. The frame of lgtD varied widely: it was OOF in most but not all cases. This genotype would result in synthesis of polylactosamine α chains that could be sialylated. Polylactosamine α chains would enhance virulence, and their sialylation would enable gonococci to survive within polymorphonuclear cells; however, an active LgtD in a few bacteria could provide a survival advantage in other sites of infection.
    The Journal of Infectious Diseases 08/2012; 206(8):1227-32. · 5.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Most cases of cellulitis are traditionally attributed to β-hemolytic Streptococcus and Staphylococcus species, although in most cases, no organism is identified. Development of PCR using the conserved bacterial 16 S rRNA DNA permits identification of bacteria independent of conventional culture approaches and prior use of antibiotics. We used PCR-based techniques to identify cellulitis etiology using aspirate samples from affected skin. Saline was infiltrated and aspirated at the site of greatest erythema or at the cellulitic border. Samples were tested for 16 S rRNA DNA, and organism-specific probes used to identify bacteria commonly seen in skin infections. Aspirates from 32 patients were studied, and 16 S rRNA DNA was detected in nine of these patient samples (28.1 %). Bacterial species were identified by PCR methods in six of these nine samples (66.6 %), with S. aureus and methicillin-resistant S. aureus (MRSA) identified in four and two, respectively, of these samples. Of the patients with positive aspirate bacterial cultures (3/9, 33.3 %), S. aureus and coagulase-negative Staphylococcus (CoNS) were present on cultures of two of the three (both 66.6 %) positive samples. Only in one of the three positive bacterial cultures did the PCR method detect the same organism as was detected by culture. Among patients with positive provider-collected clinical cultures, MRSA was the predominant organism (11/18, 61.1 %) and when present, it was found as the sole organism. Where S. aureus or Streptococcus species were detected by molecular methods, clinical cultures yielded a positive result as well. PCR-based techniques do not appear to be more sensitive than aspirate cultures for the detection of pathogens in cellulitis.
    Infection 07/2012; 40(5):537-41. · 2.44 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chronic wounds contain complex polymicrobial communities of sessile organisms that have been underappreciated because of limitations of standard culture techniques. The aim of this work was to combine recently developed next-generation investigative techniques to comprehensively describe the microbial characteristics of chronic wounds. Tissue samples were obtained from 15 patients with chronic wounds presenting to the Johns Hopkins Wound Center. Standard bacteriological cultures demonstrated an average of three common bacterial species in wound samples. By contrast, high-throughput pyrosequencing revealed increased bacterial diversity with an average of 17 genera in each wound. Data from microbial community profiling of chronic wounds were compared with published sequenced analyses of bacteria from normal skin. Increased proportions of anaerobes, Gram-negative rods and Gram-positive cocci were found in chronic wounds. In addition, chronic wounds had significantly lower populations of Propionibacterium compared with normal skin. Using epifluorescence microscopy, wound bacteria were visualized in highly organized thick confluent biofilms or as scattered individual bacterial cells. Fluorescent in situ hybridization allowed for the visualization of Staphylococcus aureus cells in a wound sample. Quorum-sensing molecules were measured by bioassay to evaluate signaling patterns among bacteria in the wounds. A range of autoinducer-2 activities was detected in the wound samples. Collectively, these data provide new insights into the identity, organization, and behavior of bacteria in chronic wounds. Such information may provide important clues to effective future strategies in wound healing.
    Wound Repair and Regeneration 09/2011; 19(5):532-41. · 2.76 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We evaluated antimicrobial resistance in Neisseria gonorrhoeae isolated from men enrolled in a randomized trial of male circumcision to prevent HIV. Urethral specimens from men with discharge were cultured for N. gonorrhoeae. MICs were determined by agar dilution. Clinical and Laboratory Standards Institute (CLSI) criteria defined resistance: penicillin, tetracycline, and azithromycin MICs of ≥2.0 μg/ml; a ciprofloxacin MIC of ≥1.0 μg/ml; and a spectinomycin MIC of ≥128.0 μg/ml. Susceptibility to ceftriaxone and cefixime was shown by an MIC of ≤0.25 μg/ml. Additionally, PCR amplification identified mutations in parC and gyrA genes in selected isolates. From 2002 to 2009, 168 N. gonorrhoeae isolates were obtained from 142 men. Plasmid-mediated penicillin resistance was found in 65%, plasmid-mediated tetracycline resistance in 97%, and 11% were ciprofloxacin resistant (quinolone-resistant N. gonorrhoeae [QRNG]). QRNG appeared in November 2007, increasing from 9.5% in 2007 to 50% in 2009. Resistance was not detected for spectinomycin, cefixime, ceftriaxone, or azithromycin, but MICs of cefixime (P = 0.018), ceftriaxone (P < 0.001), and azithromycin (P = 0.097) increased over time. In a random sample of 51 men, gentamicin MICs were as follows: 4 μg/ml (n = 1), 8 μg/ml (n = 49), and 16 μg/ml (n = 1). QRNG increased rapidly and alternative regimens are required for N. gonorrhoeae treatment in this area. Amid emerging multidrug-resistant N. gonorrhoeae, antimicrobial resistance surveillance is essential for effective drug choice. High levels of plasmid-mediated resistance and increasing MICs for cephalosporins suggest that selective pressure from antibiotic use is a strong driver of resistance emergence.
    Antimicrobial Agents and Chemotherapy 05/2011; 55(8):3882-8. · 4.57 Impact Factor
  • R M Brotman, J H Melendez, K G Ghanem
    [Show abstract] [Hide abstract]
    ABSTRACT: We aimed to test the hypothesis that a short anovaginal distance may increase the risk of bacterial vaginosis (BV) due to faecal contamination and disruption of the vaginal microbiota. Women attending two sexually transmitted infection (STI) clinics in Baltimore, Maryland, USA, who complained of a vaginal discharge were asked to participate in a study to measure mucosal immune responses. In this pilot study of all enrolled women, a small plastic ruler was used to measure the anatomic distance from the posterior fourchette to the anus with the participant in the lithotomy position. Cases of BV, defined by Amsel's clinical criteria (n = 62), were compared with controls (n = 31) without BV. We used linear and logistic regression models to adjust for potential confounders. A total of 93 women were recruited (median age 28.6 years, 93% black, 4.4% gonorrhoea infection, 7.4% chlamydia infection, 8.6% trichomonas infection, 67% BV diagnosed). Mean anovaginal distance was 3.22 cm (SD: 0.74, range 1.8-5.2) for controls and 3.37 cm (SD: 0.76, range: 1.8-5.7) for cases (P = 0.38). There was no difference between cases and controls when comparing median values, quartiles and after adjusting for potential confounders. Among high-risk women with multiple co-infections, there was no association between anovaginal distance and clinical diagnosis of BV.
    International Journal of STD & AIDS 04/2011; 22(4):231-3. · 1.00 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Rapid diagnosis of bloodstream infections (BSIs) in the emergency department (ED) is challenging, with turnaround times exceeding the timeline for rapid diagnosis. We studied the usefulness of procalcitonin as a marker of BSI in 367 adults admitted to our ED with symptoms of systemic infection. Serum samples obtained at the same time as blood cultures were available from 295 patients. Procalcitonin levels were compared with blood culture results and other clinical data obtained during the ED visit. Procalcitonin levels of less than 0.1 ng/mL were considered negative; all other levels were considered positive. In 16 patients, there was evidence of BSI by blood culture, and 12 (75%) of 16 patients had a procalcitonin level of more than 0.1 ng/mL. In 186 (63.1%) of 295 samples, procalcitonin values were less than 0.1 ng/mL, and all were culture negative. With a calculated threshold of 0.1475 ng/mL for procalcitonin, sensitivity and specificity for the procalcitonin assay were 75% and 79%, respectively. The positive predictive value was 17% and the negative predictive value 98% compared with blood cultures. Procalcitonin is a useful marker to rule out sepsis and systemic inflammation in the ED.
    American Journal of Clinical Pathology 02/2011; 135(2):182-9. · 2.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chronic wounds cause substantial morbidity and disability. Infection in chronic wounds is clinically defined by routine culture methods that can take several days to obtain a final result, and may not fully describe the community of organisms or biome within these wounds. Molecular diagnostic approaches offer promise for a more rapid and complete assessment. We report the development of a suite of real-time PCR assays for rapid identification of bacteria directly from tissue samples. The panel of assays targets 14 common, clinically relevant, aerobic pathogens and demonstrates a high degree of sensitivity and specificity using a panel of organisms commonly associated with chronic wound infection. Thirty-nine tissue samples from 29 chronic wounds were evaluated and the results compared with those obtained by culture. As revealed by culture and PCR, the most common organisms were methicillin-resistant Staphylococcus aureus (MRSA) followed by Streptococcus agalactiae (Group B streptococcus) and Pseudomonas aeruginosa. The sensitivities of the PCR assays were 100% and 90% when quantitative and qualitative culture results were used as the reference standard, respectively. The assays allowed the identification of bacterial DNA from ten additional organisms that were not revealed by quantitative or qualitative cultures. Under optimal conditions, the turnaround time for PCR results is as short as 4-6 h. Real-time PCR is a rapid and inexpensive approach that can be easily introduced into clinical practice for detection of organisms directly from tissue samples. Characterization of the anaerobic microflora by real-time PCR of chronic wounds is warranted.
    Clinical Microbiology and Infection 12/2010; 16(12):1762-9. · 4.58 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Controlling for sample site is considered to be an important aspect of chronic wound microbiological investigations; yet, macroscale spatial variation in wound microbiota has not been well characterized. A total of 31 curette samples were collected at the leading edge, opposing leading edge, and/or center of 13 chronic wounds. Bacterial community composition was characterized using a combination of 16S rRNA gene-based pyrosequencing; heat map display; hierarchical clustering; nonmetric multidimensional scaling; and permutation multivariate analysis of variance. A total of 58 bacterial families and 91 bacterial genera were characterized among the 13 wounds. While substantial macroscale spatial variation was observed among the wounds, bacterial communities at different sites within individual wounds were significantly more similar than those in different wounds (p=0.001). Our results support the prevalent opinion that controlling for sample site may improve the quality of wound microbiota studies; however, the significant similarity in bacterial communities from different sites within individual wounds indicates that studies failing to control for sampling site should not be disregarded based solely on this criterion. A composite sample from multiple sites across the surface of individual wounds may provide the most robust characterization of wound microbiota.
    Wound Repair and Regeneration 10/2010; 19(1):80-8. · 2.76 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Self-reported sexual behaviors are subject to bias. We previously developed a polymerase chain reaction for the detection of Y-chromosome sequences in vaginal fluid as a potential biomarker of recent sexual activity. In this study, we found menses results in lower Y-chromosome concentrations but with similar decay patterns as non-menstrual samples.
    Sexually transmitted diseases 01/2010; 37(1):1-4. · 2.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: ABSTRACT Chronic wounds cause substantial morbidity and disability. Infection in chronic wounds is clinically defined by routine culture methods which take several days to finalize, and may not fully describe the community of organisms or biome within these wounds. Molecular diagnostic approaches offer promise for more rapid and complete assessment. We report the development of a suite of Real-Time PCR assays for rapid identification of bacteria directly from tissue samples. The panel of assays targets 14 common, clinically-relevant, aerobic pathogens, and demonstrated a high degree of sensitivity and specificity against a panel of organisms commonly associated with chronic wound infection. Thirty-nine tissue samples from 29 chronic wounds were evaluated and the results compared to cultures. By culture and PCR, the most common organisms were Methicillin Resistant Staphylococcus aureus (MRSA) followed by Streptococcus agalactiae (Group B streptococcus: GBS) and Pseudomonas aeruginosa. The sensitivities of the PCR assays were 100% and 90% when quantitative and qualitative culture results were used as the gold standard, respectively. The assays identified bacterial DNA from 10 additional organisms that were not reported by quantitative or qualitative cultures. Under optimal conditions, turnaround for PCR results is as little as 4-6 hours. Real-Time PCR is a rapid and inexpensive approach, which can be easily translated into clinical practice for detection of organisms directly from tissue samples. Characterization of the anaerobic microflora by Real-Time PCR of chronic wounds is warranted.
    Clinical Microbiology and Infection 12/2009; · 4.58 Impact Factor
  • Archives of dermatology 10/2009; 145(10):1193-5. · 4.76 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacterial colonization is hypothesized to play a pathogenic role in the non-healing state of chronic wounds. We characterized wound bacteria from a cohort of chronic wound patients using a 16S rRNA gene-based pyrosequencing approach and assessed the impact of diabetes and antibiotics on chronic wound microbiota. We prospectively enrolled 24 patients at a referral wound center in Baltimore, MD; sampled patients' wounds by curette; cultured samples under aerobic and anaerobic conditions; and pyrosequenced the 16S rRNA V3 hypervariable region. The 16S rRNA gene-based analyses revealed an average of 10 different bacterial families in wounds--approximately 4 times more than estimated by culture-based analyses. Fastidious anaerobic bacteria belonging to the Clostridiales family XI were among the most prevalent bacteria identified exclusively by 16S rRNA gene-based analyses. Community-scale analyses showed that wound microbiota from antibiotic treated patients were significantly different from untreated patients (p = 0.007) and were characterized by increased Pseudomonadaceae abundance. These analyses also revealed that antibiotic use was associated with decreased Streptococcaceae among diabetics and that Streptococcaceae was more abundant among diabetics as compared to non-diabetics. The 16S rRNA gene-based analyses revealed complex bacterial communities including anaerobic bacteria that may play causative roles in the non-healing state of some chronic wounds. Our data suggest that antimicrobial therapy alters community structure--reducing some bacteria while selecting for others.
    PLoS ONE 02/2009; 4(7):e6462. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To examine the concordance between teens' and young adults' self-reported condom use, assessed by audio-computer-assisted self-interviewing, and Y-chromosome polymerase chain reaction (Yc-PCR) assay, a nondisease marker for detecting the presence of sperm in vaginal fluid for 14 days after unprotected vaginal sex. Randomized trial of a human immunodeficiency virus prevention program. Only data from baseline (before randomization) were used for this analysis. A clinic-based sample in Atlanta, Georgia. Eligible teens and young adults were African American female teens and young adults 15 to 21 years old who had reported sexual activity in the previous 60 days. Of 1558 teens and young adults screened from March 1, 2002, through August 31, 2004, 847 were eligible and 715 (84.4%) participated at baseline. Self-reported consistent condom use in the 14 days before baseline and Yc-PCR results. Of participants who reported vaginal sex in the past 14 days, 186 reported consistent condom use, defined as 100% condom use. Of these, 63 had a positive Yc-PCR result, indicating detection of the Y chromosome in the vaginal fluid. Participants who reported consistent condom use with a self-reported history of sexually transmitted diseases were 2.4 times more likely to have a positive Yc-PCR result (adjusted odds ratio, 2.4; 95% confidence interval, 1.2-4.8; P = .01). A significant degree of discordance between self-reports of consistent condom use and Yc-PCR positivity was observed. Several rival explanations for the observed discordance exist, including (1) teens and young adults inaccurately reported condom use; (2) teens and young adults used condoms consistently but used them incorrectly, resulting in user error; and (3) teens and young adults responded with socially desirable answers. Using an objective biological measure may provide one strategy for validating teens' and young adults' self-reported condom use.
    JAMA Pediatrics 02/2009; 163(1):61-4. · 4.28 Impact Factor
  • Johan Melendez, Jonathan Zenilman
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Antimicrobial resistance of Neisseria gonorrhea (NG) is a major public health problem. With the emergence of quinolone resistance, there are limited available therapy options, centering on 3rd generation cephalosporins. Options for B-lactams-allergic patients are also limited. We evaluated a panel of contemporary NG isolates, predominantly quinolone-resistant NG (QRNG), against Gentamicin (GNT), which has been used for NG treatment, Chloramphenicol (CHL) and Rifampin (RIF) which have high oral bioavailability. Methods: NG isolates were obtained from multiple cities through collaborative surveillance projects. Antimicrobial susceptibility was determined using Etest. The ranges, MIC50 and MIC90 were calculated for the drugs above, as well as penicillin (PEN), ceftriaxone (CTX) and ciprofloxacin (CIP). QRNG resistance determinants were identified by PCR. Results: The distribution of MICs and susceptibility profile are presented in the table. All 39 NG isolates evaluated were susceptible to CTX, and GNT. All CIP-sensitive isolates were sensitive to CHL. All CIP-resistant isolates had documented mutations in the quinolone-resistant determining region. We were surprised by the high proportion of isolates with decreased RIF and CHL susceptibilities, 36% and 33%, respectively. Conclusions: Finding independent and combined reduced susceptibility to RIF and CHL in QRNG isolates suggests that these drugs are not viable NG therapy options. Further research is needed to characterize the mechanisms and source of these resistance factors, especially since neither drug is used for NG. The fact that CHL has not been widely used for > 30 years suggests an environmental source of the resistance determinants. MICs and Resistance Distribution for N. gonorrhoeae Isolates MIC (mg/L) Susceptibility Antimicrobial Agent N. of isolates 50% 90% Range Sensitive (%) Resistant (%) Ceftriaxone 39 0.015 0.06 0.015 - 0.06 100 0 Gentamicin 24 4 6 1.5 - 6 100 0 Chloramphenicol 39 2 4 0.25 - 4 67 33 Rifampin 24 0.125 32 0.06 - 32 64 36 Penicillin 24 1 2 0.06 - 2 58 42 Ciprofloxacin 39 4 16 0.002 - 32 42 58
    Infectious Diseases Society of America 2008 Annual Meeting; 10/2008

Publication Stats

248 Citations
74.49 Total Impact Points


  • 2007–2014
    • Johns Hopkins University
      • • Department of Medicine
      • • Department of Pathology
      • • Department of Community-Public Health Nursing
      Baltimore, Maryland, United States
  • 2011
    • University of Illinois at Chicago
      • Division of Epidemiology and Biostatistics
      Chicago, IL, United States
  • 2010
    • University of Maryland, Baltimore
      • Institute for Genome Sciences
      Baltimore, MD, United States
  • 2009–2010
    • Translational Genomics Research Institute
      Phoenix, Arizona, United States
  • 2008–2010
    • Johns Hopkins Medicine
      • Division of Infectious Diseases
      Baltimore, MD, United States