Antimicrobial susceptibility of Neisseria gonorrhoeae isolated in Jiangsu Province, China, with a focus on fluoroquinolone resistance

The frequency of mutations in the penA, mtrR, gyrA and parC genes of Neisseria gonorrhoeae, the presence of tetM gene and antibiotic resistance/susceptibility: a systematic review and meta-analyses

Gonorrhoea is currently one of the most important sexually transmitted infections (STIs) due to the increasing spread of multidrug-resistant strains of N. gonorrhoeae. The aim of this study was to analyse the association between resistance or decreased susceptibility to antibiotics in N. gonorrhoeae and the presence of mutations in the penA, mtrR, gyrA and parC genes, and the presence of tetM gene. We conducted a systematic review according to the PRISMA guidelines. We selected 19 studies for the penA gene, 23 for gyrA and parC, 18 for mtrR and 12 for tetM using the Science Direct and PubMed databases. Meta-analyses of isolates resistant to penicillin, cefixime and ceftriaxone showed that more than 50% of isolates had mutations in the penA and mtrR genes. More than 50% of azithromycin-resistant isolates had mutations in the mtrR gene, while more than 50% of ciprofloxacin-resistant and intermediate-resistant isolates had mutations in gyrA. Less than 50% of the isolates with intermediate resistance to ciprofloxacin had mutations in parC. The plasmid containing the tetM gene was found in more than 50% of tetracycline-resistant isolates. Infection surveillance and genetic studies are important for controlling the spread of the disease, which can improve the quality of life of infected people and reduce the financial burden on public health systems.

Exploring quinolone resistance-determining region in Neisseria gonorrhoeae isolates from across India

Background & objectives:

Antimicrobial resistance in Neisseria gonorrhoeae, the causative agent of gonorrhoea, is a subject of worldwide attention. The present study was undertaken to examine the rates of ciprofloxacin resistance, to correlate mutations in gyrA and parC genes with the level of resistance and to look for a variation in mutation pattern, if any, in isolates from across the country.

Methods:

A total of 113 isolates of N. gonorrhoeae collected from sexually transmitted infection patients in six centres during November 2010 to October 2013 were investigated. Minimum inhibitory concentration (MIC) determination was done by E-test and results interpreted as per Calibrated Dichotomous Sensitivity criteria. DNA sequence analysis of gyrA and parC genes was done.

Results:

Of the 113 isolates, only three (2.6%) were susceptible whereas eight (7.07%) were less susceptible, 32 [28.3%, 95% confidence interval (CI): 20.4-37.6%] resistant (MIC 1-3 µg/ml) and 70 (61.9%, 95% CI: 52.2-70.7%) exhibited high-level resistance (HLR) (MIC ≥4 µg/ml) to ciprofloxacin. A S91F substitution in gyrA gene was demonstrated in all ciprofloxacin non-susceptible isolates. All resistant and HLR isolates had a double mutation in gyrA gene. However, only 5.7 per cent of HLR isolates showed double mutations in parC gene. One isolate (MIC 32 µg/ml) had a previously undescribed G85D substitution in the parC gene.

Interpretation & conclusions:

A S91F substitution in gyrA gene was seen in all non-susceptible isolates of N. gonorrhoeae. It may be used as a marker for ciprofloxacin resistance for molecular surveillance approaches to complement the culture-based methods.

Metataxonomic and Metagenomic Approaches vs. Culture-Based Techniques for Clinical Pathology

Diagnoses that are both timely and accurate are critically important for patients with life-threatening or drug resistant infections. Technological improvements in High-Throughput Sequencing (HTS) have led to its use in pathogen detection and its application in clinical diagnoses of infectious diseases. The present study compares two HTS methods, 16S rRNA marker gene sequencing (metataxonomics) and whole metagenomic shotgun sequencing (metagenomics), in their respective abilities to match the same diagnosis as traditional culture methods (culture inference) for patients with ventilator associated pneumonia (VAP). The metagenomic analysis was able to produce the same diagnosis as culture methods at the species-level for five of the six samples, while the metataxonomic analysis was only able to produce results with the same species-level identification as culture for two of the six samples. These results indicate that metagenomic analyses have the accuracy needed for a clinical diagnostic tool, but full integration in diagnostic protocols is contingent on technological improvements to decrease turnaround time and lower costs.

Antimicrobial resistance monitoring in Neisseria gonorrhoeae and strategic use of funds from the Global Fund to set up a systematic Moroccan gonococcal antimicrobial surveillance programme

OBJECTIVES

The aims of this study were to assess antimicrobial resistance in Neisseria gonorrhoeae infections and update the treatment in the national guidelines for the syndromic management of sexually transmitted infections in Morocco.

METHODS

171 men complaining of urethral discharge were recruited from basic health services during 2009. Urethral swab samples were collected and N gonorrhoeae identification was performed by culture. Antimicrobial susceptibility testing was performed using the Etest method and the antimicrobial agents tested were ciprofloxacin, penicillin, spectinomycin, tetracycline, ceftriaxone and cefixime.

RESULTS

A total of 72 isolates were examined. Significant resistance to tetracycline (92.8%) and ciprofloxacin (86.8%), which was used as first-line treatment in gonococcal infections, was noted. No resistance to spectinomycin, ceftriaxone or cefixime was detected in all the isolates.

CONCLUSIONS

Following these results the Ministry of Health of Morocco replaced ciprofloxacin and introduced ceftriaxone 250 mg as a single dose in the treatment of gonococcal infections. Using funds from the Global Fund to Fight AIDS, Tuberculosis and Malaria (the Global Fund), a surveillance programme was set up for antimicrobial resistance testing in N gonorrhoeae.

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

TaqMan real-time quantitative PCR assay for detection of fluoroquinolone-resistant Neisseria gonorrhoeae

It is noted that more than 99 % of fluoroquinolone resistance in Neisseria gonorrhoeae (QRNG) specimens have been shown to have the mutation of Ser91/Phe in the gyrA gene. In order to detect QRNG isolates as quickly as possible, the real-time TaqMan quantitative PCR assay was established for detection of the point mutation of Ser91/Phe in gyrA gene. The standard curve was generated automatically on ABI Prism PE7500. The correlation coefficient (r) of the standard curve was -0.9984 (R(2) = 0.9968), indicating a quietly precise log-linear relationship between the concentration of target DNA and the Ct value. Presently, correlated, cultured antimicrobial susceptibility testing of N. gonorrhoeae isolates continues to be the gold standard method for the detection of antimicrobial resistance. Comparison to the correlated, cultured antimicrobial susceptibility testing, the sensitivity and specificity of the established TaqMan assay for the detection of the QRNG specimens were 100 and 99 %, respectively. The TaqMan assay also allows for rapid detection of QRNG isolates without complex laboratory techniques. Therefore, real-time TaqMan quantitative PCR assay is a rapid, simple, highly sensitive, highly specific, and easy-to-perform method for the detection of the QRNG specimens. It can be applied as a quick screening method for QRNG isolates to help clinical determination of optimal treatment prescription.

Molecular characterization of quinolone-resistant Neisseria gonorrhoeae isolates from Brazil

Despite the rapid spread of antibiotic resistance among gonococci worldwide, limited reports are available from Brazilian locations. In the present study, 25 quinolone-resistant Neisseria gonorrhoeae (QRNG) strains isolated in Rio de Janeiro, Brazil, were characterized by phenotypic and molecular methods, including analysis of mutations in the gyrA and parC genes. They represented 16.5% of the N. gonorrhoeae isolates obtained during a survey performed from 2006 to 2010. A trend for increasing resistance to ciprofloxacin was observed in the period investigated. The most prevalent pattern of mutation observed among QRNG isolates, Ser-91 to Phe and Asp-95 to Gly in gyrA and Ser-87 to Arg in parC, was detected in 40% of the isolates exhibiting MICs ranging from 4 to >32 μg/ml. Rare types of mutations were found in the gyrA gene (Gln-102 to His [12%] and Asp-95 to Tyr [4%]) and in the parC gene (Ser-88 to Thr [4%]). The genetic relationship of the QRNG isolates, evaluated by pulsed-field gel electrophoresis, suggested that the increase in the frequencies of the QRNG isolates in Rio de Janeiro, Brazil, may have arisen as a result of simultaneous spread of two clonal groups. The results also indicate that fluoroquinolones may no longer be used as first line antibiotics for the treatment of gonorrhea in Rio de Janeiro, and that programs for antimicrobial susceptibility surveillance of N. gonorrhoeae should also be implemented in other regions of Brazil.

Cephalosporin Resistance in Neisseria gonorrhoeae

Gonorrhea, a disease of public health importance, not only leads to high incidence of acute infections and complications but also plays a major role in facilitating human immunodeficiency virus (HIV) acquisition and transmission. One of the major public health needs for gonorrhea control is appropriate, effective treatment. However, treatment options for gonorrhea are diminishing as Neisseria gonorrhoeae have developed resistance to several antimicrobial drugs such as sulfonamides, penicillin, tetracyclines and quinolones. Antimicrobial resistance (AMR) surveillance of N. gonorrhoeae helps establish and maintain the efficacy of standard treatment regimens. AMR surveillance should be continuous to reveal the emergence of new resistant strains, monitor the changing patterns of resistance, and be able to update treatment recommendations so as to assist in disease control. Current treatment guidelines recommend the use of single dose injectable or oral cephalosporins. The emergence and spread of cephalosporin resistant and multi drug resistant N. gonorrhoeae strains, represents a worrying trend that requires monitoring and investigation. Routine clinical laboratories need to be vigilant for the detection of such strains such that strategies for control and prevention could be reviewed and revised from time to time. It will be important to elucidate the genetic mechanisms responsible for decreased susceptibility and future resistance. There is also an urgent need for research of safe, alternative anti-gonococcal compounds that can be administered orally and have effective potency, allowing high therapeutic efficacy (greater than 95.0% cure rate).

Population dynamics of Neisseria gonorrhoeae in Shanghai, China: a comparative study

Background

Gonorrhea is a major sexually transmitted disease (STD) in many countries worldwide. The emergence of fluoroquinolone resistance has complicated efforts to control and treat this disease. We report the first study of the evolutionary processes acting on transmission dynamics of a resistant gonococcal population from Shanghai, China. We compare these findings with our previous study of the evolution of a fluoroquinolone sensitive gonococcal population from Baltimore, MD.

Methods

Ninety six gonococcal samples were collected from male patients in Shanghai, China. All samples were fluoroquinolone resistant. Seven MLST housekeeping genes, two fluoroquinolone resistance genes (gyrA and parC) and the porB gene were sequenced and subjected to population genetic and evolutionary analyses. We estimated genetic diversity, recombination, growth, and selective pressure. The evolutionary history and population dynamics of the Shanghai population were also inferred and compared with that observed in a fluoroquinolone sensitive gonococcal population from Baltimore.

Results

For both populations, mutation plays a larger role than recombination in the evolution of the porB gene, whereas the latter seems to be the main force driving the evolution of housekeeping and fluoroquinolone resistance genes. In both populations there was evidence for positively selected sites in all genes analyzed. The phylogenetic analyses showed no temporal clustering in the Shanghai gonococcal population, nor did we detect shared allelic profiles between the Shanghai and the Baltimore populations. Past population dynamics of gonococcal strains from Shanghai showed a rising relative effective population size (Ne) in MLST genes with a declining relative Ne for gyrA and parC, whereas among sensitive strains from Baltimore we previously observed concordance among these genes. In both Shanghai and Baltimore, the past population dynamics of gonococcal strains tracked changes in the prevalence of gonorrhea.

Conclusions

Our study illustrates both similarities and differences in the evolutionary processes acting on gonococcal populations in different geographic areas. An explanation of this pattern that may apply in China is the continued use of quinolone antibiotics despite widespread resistance. Population genetic analysis of gonococcal strains in conjunction with epidemiological surveillance may provide insights into the epidemic behavior of antibiotic resistant strains and help to design control measures.

Cefepime: a reappraisal in an era of increasing antimicrobial resistance

Cefepime is a 'fourth-generation' cephalosporin with an in vitro extended-spectrum of activity against Gram-negative and Gram-positive pathogens. Cefepime is approved for the treatment of moderate-to-severe infections, such as pneumonia, uncomplicated and complicated urinary tract infections, skin and soft-tissue infections, intra-abdominal infections and febrile neutropenia. In this article, we provide a critical review of pharmacodynamics, clinical management, pharmacokinetics, metabolism, pharmacodynamic target analyses, clinical efficacy, safety and tolerability of cefepime after more than a decade of clinical use.

Surveillance of antimicrobial susceptibilities in Neisseria gonorrhoeae in Nanjing, China, 1999-2006

OBJECTIVE

To monitor the frequency and types of antibiotic resistance of Neisseria gonorrhoeae in Nanjing, China, between 1999 and 2006.

METHODS

beta-Lactamase production was determined by paper acidometric testing. Minimum inhibitory concentrations (MICs) to penicillin, ceftriaxone, tetracycline, ciprofloxacin, and spectinomycin were determined by agar plate dilution. Plasmid types were determined for TRNG and PPNG isolates by PCR.

RESULTS

One-thousand two-hundred and eight N. gonorrhoeae isolates were examined. The rate of PPNG rose from 8.0% (9 of 112) in 1999 to 57.36% (113 of 197) in 2004, and declined to 44.44% (88 of 198) in 2006. Prevalence of TRNG increased from 1.8% (2 of 112) in 1999 to 32.82% (65 of 198) in 2006. 99.23% (258 of 260) of TRNG contained the Dutch-type tetM gene and 2 strains contained the American-type tetM gene. All PPNG examined contained the Asian type plasmid. Among non-PPNG, chromosomally mediated resistance to penicillin varied from 57.84% (59 of 102) to 87.80% (72 of 82). Chromosomal resistance to ciprofloxacin (QRNG) was detected in 83.93% (94 of 112) of the strains in 1999 and 98.99% (196 of 198) in 2006. Eight spectinomycin-resistant N. gonorrhoeae strains were detected between 2001 and 2006. None of the gonococcal isolates tested was resistant to ceftriaxone but decreased susceptibility was observed in some strains.

CONCLUSIONS

Among N. gonorrhoeae strains isolated in Nanjing, China, plasmid mediated resistance including PPNG and TRNG increased significantly between 1999 and 2006. Chromosomally mediated resistance to both penicillin and ciprofloxacin was also high during this period. Spectinomycin resistance of N. gonorrhoeae was sporadic. Ceftriaxone and spectinomycin can be considered effective antimicrobial agents for the treatment of gonorrhea in Nanjing at the present time.

Changing trends of antimicrobial susceptibility patterns of Neisseria gonorrhoeae in India and the emergence of ceftriaxone less susceptible N. gonorrhoeae strains

OBJECTIVES

To monitor the trend of antimicrobial susceptibility of Neisseria gonorrhoeae isolates from 2002 to 2006 in New Delhi, India under the Gonococcal Antimicrobial Susceptibility Programme and to document the emergence of any new antimicrobial resistance.

METHODS

Antimicrobial susceptibility of 382 N. gonorrhoeae isolates from clinical cases in males and females to penicillin, tetracycline, ciprofloxacin, spectinomycin and ceftriaxone was determined by disc diffusion technique, using WHO reference strains as controls and WHO interpretative criteria. MICs were determined using Etests.

RESULTS

A significant increasing trend of penicillin and ciprofloxacin resistance up to 2003 and 2004, respectively, and subsequent decrease in resistant strains with a concomitant increase in less susceptible strains, was observed. Tetracycline-resistant N. gonorrhoeae increased significantly from 6.7% in 2002 to 22.9% in 2005. Only one isolate was resistant to spectinomycin and nine isolates were less susceptible to ceftriaxone, during this 5 year period. A substantial proportion (23.3%) of strains were multiresistant.

CONCLUSIONS

Emergence of ceftriaxone less susceptible N. gonorrhoeae isolates is a cause for concern, although treatment failure was not observed. An active, continuous and comprehensive programme for monitoring and surveillance of antimicrobial resistance needs to be established in many laboratories, and a search for new effective agents needs to be initiated to respond to the emergence of resistant isolates.