A blood isolate of Neisseria meningitidis showing reduced susceptibility to quinolones in Hong Kong

Prevalence, sequence type, and quinolone resistance of Neisseria lactamica carried in children younger than 15 years in Shanghai, China

OBJECTIVE

Neisseria lactamica has an important influence on carriage and antimicrobial susceptibility of N. meningitidis, a major pathogen of septicemia and meningitis. In China, quinolone resistance is highly prevalent in N. meningitidis but unknown in N. lactamica. This study investigates the carriage rate, sequence type, and ciprofloxacin resistance of N. lactamica in children in China.

METHODS

During 2014-2016, throat swabs were collected from 2,239 children in Shanghai. The ciprofloxacin minimum inhibitory concentrations of the isolates were determined by the agar dilution method.

RESULTS

The overall carriage rate of N. lactamica was higher (8.9%) than that of N. meningitidis (0.9%) and peaked at two years (37.1%). The resistance frequency of N. lactamica to ciprofloxacin was 98.5% (197/200). There were 65 sequence types (STs). Clonal complex (cc) 640 (45.5%) dominated, while ST-14031 was predominant (37%, 74/200). All isolates possessed a GyrA mutation; 17 isolates (8.5%) harbored additionally a ParC mutation. Assigned to 39 different alleles, the gyrA sequences from these N. lactamica isolates formed an N. lactamica cluster, which also included eight alleles from N. meningitidis.

CONCLUSION

The N. lactamica isolates in China showed distinct characteristics with lower genetic diversity and a much higher prevalence of quinolone resistance than in other countries.

Ciprofloxacin-resistant Neisseria meningitidis in Canada: likely imported strains

The prevalence of ciprofloxacin-resistant Neisseria meningitidis in Canada was studied by testing 346 isolates received at the National Microbiology Laboratory during the calendar years 2013 to 2015. Of the 277 individual invasive and 69 noninvasive isolates tested, only 2 serogroup C (MenC) isolates were found to be resistant to ciprofloxacin. Both MenC were typed as sequence type (ST)-4821, a unique clone found mainly in China, thus suggesting both isolates might be from travel-related or imported cases. This prompted us to also examine 6 serogroup A (MenA) isolates in our collection, since MenA is not currently endemic in Canada. Three MenA from 2006 were resistant to ciprofloxacin and they were typed as ST-4789. A ciprofloxacin-resistant MenA strain of ST-4789 was responsible for a meningococcal disease outbreak in Delhi, India, in 2005 to 2006. The 2 MenC and 3 MenA ciprofloxacin-resistant N. meningitidis were from patients residing in British Columbia.

Shifts in the Antibiotic Susceptibility, Serogroups, and Clonal Complexes of Neisseria meningitidis in Shanghai, China: A Time Trend Analysis of the Pre-Quinolone and Quinolone Eras

BACKGROUND

Fluoroquinolones have been used broadly since the end of the 1980s and have been recommended for Neisseria meningitidis prophylaxis since 2005 in China. The aim of this study was to determine whether and how N. meningitidis antimicrobial susceptibility, serogroup prevalence, and clonal complex (CC) prevalence shifted in association with the introduction and expanding use of quinolones in Shanghai, a region with a traditionally high incidence of invasive disease due to N. meningitidis.

METHODS AND FINDINGS

A total of 374 N. meningitidis isolates collected by the Shanghai Municipal Center for Disease Control and Prevention between 1965 and 2013 were studied. Shifts in the serogroups and CCs were observed, from predominantly serogroup A CC5 (84%) in 1965-1973 to serogroup A CC1 (58%) in 1974-1985, then to serogroup C or B CC4821 (62%) in 2005-2013. The rates of ciprofloxacin nonsusceptibility in N. meningitidis disease isolates increased from 0% in 1965-1985 to 84% (31/37) in 2005-2013 (p < 0.001). Among the ciprofloxacin-nonsusceptible isolates, 87% (27/31) were assigned to either CC4821 (n = 20) or CC5 (n = 7). The two predominant ciprofloxacin-resistant clones were designated ChinaCC4821-R1-C/B and ChinaCC5-R14-A. The ChinaCC4821-R1-C/B clone acquired ciprofloxacin resistance by a point mutation, and was present in 52% (16/31) of the ciprofloxacin-nonsusceptible disease isolates. The ChinaCC5-R14-A clone acquired ciprofloxacin resistance by horizontal gene transfer, and was found in 23% (7/31) of the ciprofloxacin-nonsusceptible disease isolates. The ciprofloxacin nonsusceptibility rate was 47% (7/15) among isolates from asymptomatic carriers, and nonsusceptibility was associated with diverse multi-locus sequence typing profiles and pulsed-field gel electrophoresis patterns. As detected after 2005, ciprofloxacin-nonsusceptible strains were shared between some of the patients and their close contacts. A limitation of this study is that isolates from 1986-2004 were not available and that only a small sample of convenience isolates from 1965-1985 were available.

CONCLUSIONS

The increasing prevalence of ciprofloxacin resistance since 2005 in Shanghai was associated with the spread of hypervirulent lineages CC4821 and CC5. Two resistant meningococcal clones ChinaCC4821-R1-C/B and ChinaCC5-R14-A have emerged in Shanghai during the quinolone era. Ciprofloxacin should be utilized with caution for the chemoprophylaxis of N. meningitidis in China.

Genetic diversity and clonal characteristics of ciprofloxacin-resistant meningococcal strains in China

The purpose of the present study was to identify the clonal characteristics and gyrA gene diversity of ciprofloxacin-resistant meningococcal strains in China. One hundred and forty-one ciprofloxacin-resistant and 103 ciprofloxacin-susceptible meningococcal strains were selected for multilocus sequence typing. Of these, 54 ciprofloxacin-resistant and 42 ciprofloxacin-susceptible strains were selected for gyrA gene sequencing. Of the three clonal complexes prevalent in China, serogroup A of ST-5 complex (CC5) and serogroup C/B strains of CC4821 had a high proportion of ciprofloxacin resistance, whereas CC11 serogroup W strains were all susceptible. Nucleotide and amino acid sequences of the gyrA gene among ciprofloxacin-resistant strains showed more diversity than those among ciprofloxacin-susceptible strains. All ciprofloxacin-resistant strains had a T91I mutation and the ciprofloxacin-susceptible strains had no T91I mutation. Phylogenetic analysis showed that the gyrA gene sequences of CC4821 serogroup B/C strains, CC11 serogroup W, CC1 serogroup A, ciprofloxacin-susceptible CC5 serogroup A and reference strains had high similarity. By contrast, the ciprofloxacin-resistant CC5 serogroup A strains had a highly conserved gyrA gene sequence which was different (94.8% similarity) from that in the above strains. The results of our investigation showed that the high proportion of ciprofloxacin resistance in Neisseria meningitidis is associated with certain sequence types (STs) or clonal complexes (CCs). The prevalence of certain CCs with a high proportion of ciprofloxacin resistance can facilitate the spread of ciprofloxacin resistance.

Resistance surveillance studies: a multifaceted problem--the fluoroquinolone example

INTRODUCTION

This review summarizes data on the fluoroquinolone resistance epidemiology published in the previous 5 years.

MATERIALS AND METHODS

The data reviewed are stratified according to the different prescription patterns by either primary- or tertiary-care givers and by indication. Global surveillance studies demonstrate that fluoroquinolone- resistance rates increased in the past several years in almost all bacterial species except Staphylococcus pneumoniae and Haemophilus influenzae causing community-acquired respiratory tract infections (CARTIs), as well as Enterobacteriaceae causing community-acquired urinary tract infections. Geographically and quantitatively varying fluoroquinolone resistance rates were recorded among Gram-positive and Gram-negative pathogens causing healthcare-associated respiratory tract infections. One- to two-thirds of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) were fluoroquinolone resistant too, thus, limiting the fluoroquinolone use in the treatment of community- as well as healthcare-acquired urinary tract and intra-abdominal infections. The remaining ESBL-producing or plasmid-mediated quinolone resistance mechanisms harboring Enterobacteriaceae were low-level quinolone resistant. Furthermore, 10-30 % of H. influenzae and S. pneumoniae causing CARTIs harbored first-step quinolone resistance determining region (QRDR) mutations. These mutants pass susceptibility testing unnoticed and are primed to acquire high-level fluoroquinolone resistance rapidly, thus, putting the patient at risk. The continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some current guidelines for the treatment of intra-abdominal infections or even precludes the use of fluoroquinolones in certain indications like gonorrhea and pelvic inflammatory diseases in those geographic areas in which fluoroquinolone resistance rates and/or ESBL production is high. Fluoroquinolone resistance has been selected among the commensal flora colonizing the gut, nose, oropharynx, and skin, so that horizontal gene transfer between the commensal flora and the offending pathogen as well as inter- and intraspecies recombinations contribute to the emergence and spread of fluoroquinolone resistance among pathogenic streptococci. Although interspecies recombinations are not yet the major cause for the emergence of fluoroquinolone resistance, its existence indicates that a large reservoir of fluoroquinolone resistance exists. Thus, a scenario resembling that of a worldwide spread of β-lactam resistance in pneumococci is conceivable. However, many resistance surveillance studies suffer from inaccuracies like the sampling of a selected patient population, restricted geographical sampling, and undefined requirements of the user, so that the results are biased. The number of national centers is most often limited with one to two participating laboratories, so that such studies are point prevalence but not surveillance studies. Selected samples are analyzed predominantly as either hospitalized patients or patients at risk or those in whom therapy failed are sampled; however, fluoroquinolones are most frequently prescribed by the general practitioner. Selected sampling results in a significant over-estimation of fluoroquinolone resistance in outpatients. Furthermore, the requirements of the users are often not met; the prescribing physician, the microbiologist, the infection control specialist, public health and regulatory authorities, and the pharmaceutical industry have diverse interests, which, however, are not addressed by different designs of a surveillance study. Tools should be developed to provide customer-specific datasets.

CONCLUSION

Consequently, most surveillance studies suffer from well recognized but uncorrected biases or inaccuracies. Nevertheless, they provide important information that allows the identification of trends in pathogen incidence and antimicrobial resistance.

Meningococcal disease in Asia: an under-recognized public health burden

A literature search traced existing information on meningococcal disease in Asia. Reviewed data describing the epidemiology of meningococcal disease in Asia are incomplete, due in part to absence of surveillance in many countries, poor bacterial detection methods and social and healthcare barriers to disease reporting. This suggests that meningococcal disease in some Asian countries may be under-recognized, with a need to introduce/improve existing surveillance and case identification systems. Nevertheless, in some developing Asian countries, the disease burden may be significant. Serogroup A meningococcal epidemics are responsible for high morbidity and mortality in some countries and continue to be an ongoing threat, particularly in developing countries. There is an increasing role played by serogroups C, Y, and W-135 in invasive disease, indicating evolving meningococcal disease epidemiology in some countries. Multivalent meningococcal conjugate vaccines offer new opportunities in the region for reducing the meningococcal disease burden.

Emerging resistance in Neisseria meningitidis and Neisseria gonorrhoeae

The value of monitoring antimicrobial resistance is particularly significant for Neisseria meningitidis and Neisseria gonorrhoeae diseases, even if it is for different reasons. Although there is no global alert for the spread of resistant meningococcal strains, the emergence of resistance is correlated to the outcome of treatment and the successful prophylaxis of close contacts. Few cases of resistance among meningococci have been recorded worldwide; it remains unclear what intriguing mechanism is responsible for maintaining resistance in these cases in the absence of significant antibiotic selective pressure, as in the case of penicillin; on the contrary, although rifampicin is the antibiotic of choice in the prophylaxis of close contacts, there is a very low rate of resistance. The emergence of multidrug-resistant N. gonorrhoeae is a great challenge in controlling gonorrhea as one of the main sexually transmitted bacterial diseases. International surveillance programs permit the monitoring of the susceptibility of the pathogen and allow the revision of the standardized treatment regimen when the situation changes.

Determination of CEM-101 activity tested against clinical isolates of Neisseria meningitidis from a worldwide collection

The activity of CEM-101, a fluoroketolide, was compared to those of 11 other antimicrobial agents using the reference broth microdilution method tested against 103 Neisseria meningitidis strains, including ciprofloxacin-nonsusceptible isolates with confirmed gyrA (T91I) mutations. Among the tested isolates, 79.6% were serogroup B or C and all isolates were susceptible to ceftriaxone, azithromycin, minocycline, and rifampin. However, penicillin-nonsusceptible strains were observed (15.5%) and susceptibility to trimethoprim-sulfamethoxazole was only 50.5%. CEM-101 was the most active macrolide-like compound (MIC(90), < or = 0.015 microg/ml) compared with MIC(90)s of telithromycin (MIC(90), 0.03 microg/ml), azithromycin and clarithromycin (MIC(90), 0.12 microg/ml), and erythromycin (MIC(90), 0.25 microg/ml). CEM-101 could provide a potent alternative for the prophylaxis of meningococcal disease.

Antibiotic susceptibility and characteristics of Neisseria meningitidis isolates from the African meningitis belt, 2000 to 2006: phenotypic and genotypic perspectives

Up-to-date information regarding the antibiotic susceptibility of Neisseria meningitidis strains from African countries is highly limited. Our aim was to comprehensively describe the antibiotic susceptibilities of a selection of N. meningitidis isolates recovered between 2000 and 2006 from 18 African countries, mainly those within the meningitis belt. Susceptibilities to 11 antibiotics were determined using Etest for 137 N. meningitidis isolates (stringently selected from 693 available isolates). The isolates were also characterized by serogrouping, multilocus sequence typing, genosubtyping, and penA allele identification. All N. meningitidis isolates were susceptible to ceftriaxone, chloramphenicol, and ciprofloxacin. No isolate produced beta-lactamase. Only three isolates (2%) displayed reduced susceptibility to penicillin G. The two isolates with the highest penicillin G MICs were the only isolates showing reduced susceptibility to ampicillin and cefuroxime. One of these isolates was also resistant to penicillin V. One percent of isolates displayed reduced susceptibility to rifampin, while 52% of the isolates were resistant to tetracycline, 74% were resistant to erythromycin, and 94% were resistant to sulfadiazine. The MICs of rifampin and tetracycline seemed to be associated with the serogroup of the isolates. In total, 18 sequence types (STs), 10 genosubtypes, and 8 different penA alleles were identified; the most common were ST-7, P1.20,9,35-1, and penA4, respectively. A high level of correlation was found between ST, genosubtype, and penA allele. In conclusion, N. meningitidis isolates from the African meningitis belt remain highly susceptible to the antibiotics used. Regarding beta-lactam antibiotics, rare isolates showed a reduced susceptibility to penicillins, but the expanded-spectrum cephalosporins are not affected at present.

Nalidixic acid disk for laboratory detection of ciprofloxacin resistance in Neisseria meningitidis

Recently the CLSI recommended a disk diffusion method and breakpoints for meningococci which include breakpoints derived for nalidixic acid which serve as surrogate markers for gyrase A mutations associated with diminished fluoroquinolone susceptibility. This study presents the application of this methodology to a panel of 57 meningococcal strains isolated in Spain that include all levels of susceptibility to ciprofloxacin. In conclusion, the most useful method to predict isolates with gyrA mutations that decrease the activity of fluoroquinolones is the use of 30-microg nalidixic acid disks.