Recovery of Neisseria gonorrhoeae from 4 commercially available transport systems

Evaluation of InTray Cassettes Directly from Blood Cultures for the Diagnosis of Sepsis in Clinical Bacteriology Laboratories as an Alternative to Classic Culture Media

Culture media is fundamental in clinical bacteriology for the detection and isolation of bacterial pathogens. However, in-house media preparation could be challenging in low-resource settings. InTray^® cassettes (Biomed Diagnostics) could be a valid alternative as they are compact, ready-to-use media preparations. In this study, we evaluate the use of two InTray media as a subculture alternative for the diagnosis of bloodstream infections: the InTray^® Müller-Hinton (MH) chocolate and the InTray^® Colorex™ Screen. The InTray MH chocolate was evaluated in 2 steps: firstly, using simulated positive blood cultures (reference evaluation study), and secondly, using positive blood cultures from a routine clinical laboratory (clinical evaluation study). The Colorex Screen was tested using simulated poly-microbial blood cultures. The sensitivity and specificity of the InTray MH chocolate were respectively 99.2% and 90% in the reference evaluation study and 97.1% and 88.2% in the clinical evaluation study. The time to detection (TTD) was ≤20 h in most positive blood cultures (99.8% and 97% in the two studies, respectively). The InTray^® MH Chocolate agar showed good performance when used directly from clinical blood cultures for single bacterial infections. However, mixed flora is more challenging to interpret on this media than on Colorex™ Screen, even for an experienced microbiologist.

Neisseria gonorrhoeae culture growth rates from asymptomatic individuals with a positive nucleic acid amplification test

Gonorrhoea infections are frequently diagnosed at extragenital locations in asymptomatic individuals and are historically related to poor recovery in culture, which hinders antimicrobial susceptibility testing. The aim of this study was to evaluate recovery rates of N. gonorrhoeae by culture among asymptomatic individuals who tested positive by nucleic acid amplification tests between 2018 and 2019 in Barcelona (Spain). In total, 10,396 individuals were tested for N. gonorrhoeae on first-void urine, rectal, pharyngeal, and/or vaginal swabs depending on sexual behaviour. Overall infection prevalence was 5.5% (95% confidence interval [CI] 5.0 to 5.9%). Seven hundred and ten samples were positive corresponding to 567 individuals. The most common site of infection was the pharynx (71.3%), followed by rectum (23.1%) and genitals (4.7%) (p<0.0001). The N. gonorrhoeae recovery rate in culture, time from positive screening to culture specimen, and inoculation delay were calculated. Recovery rate was 21.7% in pharynx, 66.9% in rectum, and 37.0% in genitals (25.0% vagina, 71.4% urethra) (p<0.0001). Median culture collection time was 1 [0; 3] days, and median inoculation delay was 5.01 [4.99-7.99] hours, with no impact on N. gonorrhoeae recovery, p=0.8367 and p=0.7670, respectively. Despite efforts towards optimizing pre-analytical conditions, the N. gonorrhoeae recovery rate in asymptomatic individuals is unacceptably low (especially for pharynx), representing a problem for monitoring antimicrobial-resistant infections.

72-Hour transport recovery of antimicrobial resistant Neisseria gonorrhoeae isolates using the InTray® GC method

Recovery of Neisseria gonorrhoeae isolates exposed to a range of transport times and temperatures was quantitatively assessed for two transport devices, BioMed Diagnostics' InTray GC® and Copan Diagnostics' Liquid Amies Elution Swab (ESwab®) Collection and Transport System. Respective devices were inoculated with N. gonorrhoeae, exposed to simulated transport conditions and spread-plated from serial dilutions in duplicates onto chocolate agar in order to count CFU (colony-forming units) in the range of 25-250. Baseline CFU/mL averages of time-zero transport for each device was compared to either 24 hour (Eswab) or 72 hour (InTray GC) CFU/mL average to assess recovery of six clinical isolates of N. gonorrhoeae, and differences showing no greater than a 3 log10 (± 10%) decline between comparative time points qualified as acceptable. Our findings suggest that the InTray GC system has the potential to transport clinical isolates for ≤72 hours with acceptable N. gonorrhoeae recovery.

Targeting Culture Criteria to Maximize Culture Positivity of Neisseria gonorrhoeae in 3 Sexual Health Clinic Settings

BACKGROUND

Although most gonorrhea (GC) cases in the United States are detected using nucleic acid amplification tests (NAATs), isolation of Neisseria gonorrhoeae (NG) using culture specimens is needed for antibiotic susceptibility testing (AST). We present data on NAATs and cultures collected before and during the Centers for Disease Control and Prevention demonstration project (Strengthening the US Response to Resistant Gonorrhea [SURRG]) to describe a process to define culture criteria for NG isolation for surveillance of NG with reduced susceptibility.

METHODS

For sexually transmitted infection clinics in New York City, NY; San Francisco, CA; and Milwaukee, WI, we calculated NAAT positivity by anatomic site in 2016 (pre-SURRG) across 3 groups: (1) sex partners of persons with GC, (2) patients with symptoms (e.g., urethral or cervical discharge), (3) patients who had tested positive and were returning for GC treatment and compared it with positivity among all other patients. We then examined SURRG-period NAAT positivity among patients from whom a culture was or was not collected, and culture positivity, by specimen site and jurisdiction.

RESULTS

Pre-SURRG, NAAT positivity across the 3 select groups was at least twice that of patients who did not meet any criteria. SURRG-period NAAT positivity was higher among patients from whom a culture was also collected. Overall culture positivity was relatively high (New York City, 34.8%; San Francisco, 26.7%; Milwaukee, 24.8%); the proportion of specimens tested varied widely (range, 5.7%-26.5%) by jurisdiction.

CONCLUSIONS

Evaluation of NAAT data can inform the establishment of criteria for culture collection for AST. Routine evaluation and quality improvement activities related to culture collection/isolation techniques could increase NG isolation for AST.

Impact of Anatomic Site, Specimen Collection Timing, and Patient Symptom Status on Neisseria gonorrhoeae Culture Recovery

BACKGROUND

Neisseria gonorrhoeae culture is required for antimicrobial susceptibility testing, but recovering isolates from clinical specimens is challenging. Although many variables influence culture recovery, studies evaluating the impact of culture specimen collection timing and patient symptom status are limited. This study analyzed urogenital and extragenital culture recovery data from Centers for Disease Control and Prevention's Strengthening the US Response to Resistant Gonorrhea (SURRG) program, a multisite project, which enhances local N. gonorrhoeae culture and antimicrobial susceptibility testing capacity.

METHODS

Eight SURRG jurisdictions collected gonococcal cultures from patients with N. gonorrhoeae-positive nucleic acid amplification test (NAAT) results attending sexually transmitted disease and community clinics. Matched NAAT and culture specimens from the same anatomic site were collected, and culture recovery was assessed. Time between NAAT and culture specimen collection was categorized as same day, 1 to 7 days, 8 to 14 days, or ≥15 days, and patient symptoms were matched to the anatomic site where culture specimens were collected.

RESULTS

From 2018 to 2019, among persons with N. gonorrhoeae-positive NAAT, urethral infections resulted in the highest culture recovery (5927 of 6515 [91.0%]), followed by endocervical (222 of 363 [61.2%]), vaginal (63 of 133 [47.4%]), rectal (1117 of 2805 [39.8%]), and pharyngeal (1019 of 3678 [27.7%]) infections. Culture recovery was highest when specimens were collected on the same day as NAAT specimens and significantly decreased after 7 days. Symptoms were significantly associated with culture recovery at urethral (P = <0.0001) and rectal (P = <0.0001) sites of infection but not endocervical, vaginal, or pharyngeal sites.

CONCLUSIONS

Culture specimen collection timing and patient symptomatic status can impact culture recovery. These findings can guide decisions about culture collection protocols to maximize culture recovery and strengthen detection of antimicrobial-resistant infections.

Comparative performance of commercial Amies transport media with and without charcoal for Neisseria gonorrhoeae culture for gonococcal isolation and antimicrobial resistance monitoring in Ukraine

INTRODUCTION

Culture is the only laboratory method that provides live gonococcal isolates for monitoring antimicrobial resistance. Many clinical settings do not have direct access to laboratories for the immediate processing of biological samples. Validated and quality-assured transport media are recommended to maintain the viability of Neisseria gonorrhoeae.

METHODS

In total, 103 clinical samples were divided into two groups: 51 samples were stored in Amies agar gel medium containing charcoal and 52 samples were stored in agar gel medium without charcoal. All samples were stored at 4°C for 0.5-6 h and then transported in a thermo-protected box within 0.17-0.25 h to the laboratory of Ternopil Regional STI Clinic (Ukraine).

RESULTS

The recovery rate was significantly higher for charcoal-containing Amies medium than for charcoal-free Amies medium (86.27%, 44/51 vs. 59.62%, 31/52). A higher rate of specimens transported in charcoal-containing Amies medium was isolated within 24 h (84.31%, 43/51), whereas most isolates from charcoal-free Amies medium grew within 24 h (42.31%, 22/52) or 48 h (17.31%, 9/52). Growth beyond the first quadrant of the agar plate was registered for 59.09% (26/44) of charcoal-containing Amies samples, compared with only 19.35% (6/31) of charcoal-free Amies samples.

CONCLUSIONS

A high rate of N. gonorrhoeae recovery after transport has considerable public health implications for establishing national antimicrobial susceptibility programs. Charcoal-containing Amies medium had higher viability rate, and it could be used for diagnostic and isolation purposes in future antimicrobial susceptibility studies. Continuous validation studies of transport medium for N. gonorrhoeae culture are needed.

Low gonorrhoea antimicrobial resistance and culture positivity rates in general practice: a pilot study

OBJECTIVE

In the Netherlands, the Gonococcal Resistance to Antimicrobials Surveillance (GRAS) programme is carried out at Centres for Sexual Health (CSH), which provide care for sexual high-risk populations. However, half of gonorrhoea infections are diagnosed in general practice (GP). We performed a pilot study to explore expanding GRAS to GPs using laboratory-based surveillance. Additionally, antimicrobial resistance patterns of GP and CSH patients were compared.

METHODS

Three laboratories from different regions were included, which all perform gonorrhoea diagnostics for GPs and used ESwab for patient sampling. Additional culturing for all GP patients with gonorrhoea took place from February to July 2018. After positive PCR-nucleic acid amplification test, residual ESwab material was used for culture. In positive cultures, susceptibility testing was performed for azithromycin, ciprofloxacin, cefotaxime and ceftriaxone using Etest.

RESULTS

During the study period, 484 samples were put in culture. 16.5% of cultures were positive (n=80). Antimicrobial resistance levels were low, with 2.6% resistance to azithromycin, 21.5% to ciprofloxacin and 0.0% to cefotaxime and ceftriaxone. Resistance levels in CSH GRAS data (first half of 2018) were 19.2% for azithromycin, 31.5% for ciprofloxacin, 1.9% for cefotaxime and 0.0% for ceftriaxone.

CONCLUSIONS

Culture positivity rates for GP patients were low, probably due to long transportation times and awaiting PCR test results before attempting culture. Positivity rates might be improved by making changes in sampling and/or transportation methods, but that would require involvement of GPs and patients instead of keeping the surveillance lab based. Resistance levels appeared to be lower at GPs than at the CSH, indicating that resistance might emerge first in more high-risk populations. It is important to consider all potentially relevant patient populations when establishing a gonococcal antimicrobial resistance surveillance programme. However, based on the findings from this study the current GRAS programme will not be extended to GPs.

Expanding U.S. Laboratory Capacity for Neisseria gonorrhoeae Antimicrobial Susceptibility Testing and Whole-Genome Sequencing through the CDC's Antibiotic Resistance Laboratory Network

U.S. gonorrhea rates are rising, and antibiotic-resistant Neisseria gonorrhoeae (AR-Ng) is an urgent public health threat. Since implementation of nucleic acid amplification tests for N. gonorrhoeae identification, the capacity for culturing N. gonorrhoeae in the United States has declined, along with the ability to perform culture-based antimicrobial susceptibility testing (AST). Yet AST is critical for detecting and monitoring AR-Ng. In 2016, the CDC established the Antibiotic Resistance Laboratory Network (AR Lab Network) to shore up the national capacity for detecting several resistance threats including N. gonorrhoeae AR-Ng testing, a subactivity of the CDC's AR Lab Network, is performed in a tiered network of approximately 35 local laboratories, four regional laboratories (state public health laboratories in Maryland, Tennessee, Texas, and Washington), and the CDC's national reference laboratory. Local laboratories receive specimens from approximately 60 clinics associated with the Gonococcal Isolate Surveillance Project (GISP), enhanced GISP (eGISP), and the program Strengthening the U.S. Response to Resistant Gonorrhea (SURRG). They isolate and ship up to 20,000 isolates to regional laboratories for culture-based agar dilution AST with seven antibiotics and for whole-genome sequencing of up to 5,000 isolates. The CDC further examines concerning isolates and monitors genetic AR markers. During 2017 and 2018, the network tested 8,214 and 8,628 N. gonorrhoeae isolates, respectively, and the CDC received 531 and 646 concerning isolates and 605 and 3,159 sequences, respectively. In summary, the AR Lab Network supported the laboratory capacity for N. gonorrhoeae AST and associated genetic marker detection, expanding preexisting notification and analysis systems for resistance detection. Continued, robust AST and genomic capacity can help inform national public health monitoring and intervention.