A Cross-Sectional Study Revealing the Emergence of Erythromycin-Resistant Bordetella pertussis Carrying ptxP3 Alleles in China

Sharp rise in high-virulence Bordetella pertussis with macrolides resistance in Northern China

OBJECTIVE

To elucidate the evolution of antigen genotype and antimicrobial resistance distribution of Bordetella pertussis (B. pertussis) from 2019 to 2023 in northern China.

METHODS

Polymerase chain reaction (PCR) amplification and sequencing were utilized to identify the seven antigen genotypes (ptxA, ptxC, ptxP, prn, fim2, fim3, tcfA). E-test and Kirby-Bauer (K-B) disc diffusion were employed to determine the minimum inhibitory concentration (MIC) and zone of inhibition for B. pertussis against antimicrobial agents. Subsequently, 50 isolates were chosen for multi-locus variable-number tandem-repeat analysis (MLVA) typing and whole-genome sequencing.

RESULTS

A total of 442 B. pertussis isolates were determined. The strains with high virulence harbouring ptxP3 allele surged from 13.5% (21/155) in 2019-2021 to 93.0% (267/287) in 2022-2023. Concurrently, the erythromycin resistance B. pertussis (ERBP) in ptxP3 isolates markedly rose from 42.9% (9/21) in 2019-2021 to 100% (267/267) in 2022-2023. The majority of ptxP3 isolates (76.0%,219/288) exhibited the ptxA1/ptxC1/prn2/fim2-1/fim3A/tcfA-2 genotype. Among the 442 confirmed patients, the children aged 3-14 years escalated rapidly from 13.5% in 2019 to 45.6% in 2023. The MT28 strains were responsible for 66.0% (33/50) of the tested ones, in which ERBP was prevalent at 87.9% (29/33). All the present sequenced ptxP3-ERBP strains (31/31) were clustered into the sub-lineage IVd.

CONCLUSIONS

These results suggested the clonal spread of the ptxP3-ERBP lineage of B. pertussis with high virulence and macrolides resistance could be an important cause of the recent pertussis resurgence in China. Furthermore, the increased cases among pre-school and school-aged children underscore the importance of booster vaccination in this population.

Genomic epidemiology and evolution of Bordetella pertussis under the vaccination pressure of acellular vaccines in Beijing, China, 2020-2023

Pertussis (or whooping cough) has experienced a global resurgence despite widespread vaccine efforts. In China, the incidence of pertussis has rapidly increased, particularly following the COVID-19 pandemic. Whole-genome sequencing analysis was performed on 60 Bordetella pertussis strains isolated in Beijing from 2020-2023, and the sequences were compared with those of 635 strains from China and 943 strains from other countries. In this study, the genetic evolution of B. pertussis was investigated, focusing on key virulence genes (ptxP, ptxA, prn, fim2, fim3, tcfA) and the resistance-related locus A2047 across different periods and regions. The dominant antigen genotype among the 60 isolates was ptxP3/prn2/ptxA1/fim2-1/fim3-1/tcfA2 (88.3%), differing from the prevalent genotype ptxP-1/prn-1/ptxA-1 in Beijing prior to 2019 and the vaccine strain genotype ptxP-1/prn-1/ptxA-2/fim2-1/fim3-1/tcfA2. Evolutionary analysis revealed significant genetic shifts associated with the introduction of vaccines, particularly acellular vaccines. Initially, the prevalent genotypes included ptxP-1, prn-1, ptxA-2, fim2-2, and fim3-2. However, currently, ptxP-3, prn-2 and ptxA-1 have become predominant globally, indicating vaccine-induced selection pressure. Additionally, all 60 isolated strains (100%) presented the A2047G mutation associated with erythromycin resistance, of which ptxP3 accounted for 91.7%. Macrolide-resistant Bordetella pertussis (MRBP) is widespread in China, and the prevalence of ptxP3-MRBP may be increasing. The significant changes of dominance of subtypes in Beijing in recent years underscore the need for continuous surveillance and adaptation of pertussis vaccination strategies.

Rising pertussis cases and deaths in China: current trends and clinical solutions

Pertussis, an acute respiratory infection caused by Bordetella pertussis, has recently experienced a dramatic increase in incidence and associated deaths in China, drawing significant clinical attention. This article retrospectively analyzes national data on pertussis incidence and mortality from 2010 to 2024, exploring potential factors contributing to this trend. It also discusses strategies for enhancing vaccination programs, improving early diagnosis and treatment, and optimizing the clinical management of high-risk infants, with the aim of addressing the challenges posed by the current pertussis epidemic.

Expert consensus for pertussis in children: new concepts in diagnosis and treatment

BACKGROUND

Pertussis resurgence has been reported worldwide in the past two decades. Pertussis is still endemic and difficult to control though with universal vaccination in children. The resurgence may be related to multiple variables, such as increased disease awareness and laboratory tests, waning of immunity following vaccination, and/or genetic mutations of Bordetella pertussis. For better pertussis prevention, diagnosis, and management, we called up an expert panel to develop this expert consensus to provide new concepts in diagnosis and treatment for clinical practice.

DATA SOURCES

The expert groups collected clinical evidence, summarized their clinical experiences, evaluated preliminary recommendations or guidelines, and then organized open-ended discussions to form the recommendations. This consensus was developed by reviewing the literature and studies in databases, including PubMed, Cochrane, EMBASE, the China Biomedical Database, and the Chinese Journal Full-text Database up to May 2024. The search terms included "pertussis" or "whooping cough", "children", "diagnosis", and "treatment".

RESULTS

The burden of pertussis has also changed from infants to  school children and adults, and these age groups have consequently become the main source of infection for vulnerable population including infants and newborns. In China, a high prevalence of erythromycin-resistant Bordetella pertussis (ERBP) has been reported in the past decade. ERBP may lead to failed clinical empirical treatment with macrolides, which poses a great challenge for pertussis management and control. For better management of pertussis, a flow diagram for diagnosis and treatment of pertussis was presented in this consensus. This consensus also described the diagnostic criteria for pertussis, high-risk cases, and severe pertussis. Macrolides can still be used to treat confirmed erythromycin-sensitive B. pertussis (ESBP) infections, whereas oral trimethoprim-sulfamethoxazole therapy is the initial treatment option for children older than two months. For infants younger than two months, severe patients, or those exhibiting a high degree of sulfonamide allergy, intravenous administration of piperacillin or cefoperazone-sulbactam is advised.

CONCLUSIONS

This expert consensus provides a comprehensive guidance and a reference for the diagnosis and treatment of pertussis in children.

Molecular epidemiology and genomic features of Bordetella parapertussis in Shanghai, China, 2017-2022

Background

Pertussis is a highly contagious respiratory illness mainly caused by Bordetella pertussis (BP). Bordetella parapertussis (BPP) can induce symptoms compatible with pertussis, but has been underdiagnosed and underreported. The current pertussis vaccines offer low protection against BPP. Herein, we aim to reveal the epidemiology and genomic evolution of BPP in Shanghai, China.

Methods

Children diagnosed with BPP infection from January 2017 to December 2022 in Shanghai, China were enrolled. We performed antimicrobial susceptibility testing (AST), multiple locus variable-number tandem repeat analysis (MLVA), and whole genome sequencing (WGS) analysis. A total of 260 international BPP genomes were chosen for comparison to investigate the genomic diversity and phylogenetic characteristics of Chinese strains within a global context.

Results

Sixty patients were diagnosed with BPP infection by culture, with the positive ratio of 3.5‰ (60/17337) for BPP in nasopharyngeal swap samples. The average age of patients was 4.5 ± 0.3 years. BPPs contained four MLVA types including MT6 (65.0%), MT4 (26.7%), untype-1 (6.7%) and MT5 (1.7%), and none of strains showed resistance to macrolides. All strains carried virulence genotype of ptxP37/ptxA13/ptxB3/ptxC3/ptxD3/ptxE3/fim2-2/fim3-10. MT4 and MT5 strains carried prn54, whereas MT6 and untype-1 BPPs expressed prn101. We identified two outbreaks after 2020 caused by MT4 and MT6 strains, each corresponding to distinct WGS-based phylogenetic lineages. The MT4-lineage is estimated to have originated around 1991 and has since spread globally, being introduced to China between 2005 and 2010. In contrast, the MT6-lineage was exclusively identified in China and is inferred to have originated around 2002.

Conclusion

We revealed the genomic diversity of BPPs circulating in Shanghai, China, and reported the outbreaks of MT6 and MT4 BPPs after 2020. This is the first report on the emergence and regional outbreak of MT6 BPPs in the world, indicating that continuous surveillance on BPPs are thus required.

Whole-genome comparison of two same-genotype macrolide-resistant Bordetella pertussis isolates collected in Japan

The emergence of macrolide-resistant Bordetella pertussis (MRBP) is a significant problem because it reduces treatment options for pertussis and exacerbates the severity and spread of the disease. MRBP has been widely prevalent in mainland China since the 2010s and has been sporadically detected in other Asian countries. In Japan, two MRBP clinical strains were first isolated in Tokyo and Osaka between June and July 2018. The isolates BP616 in Osaka and BP625 in Tokyo harbored the same virulence-associated allelic genes (including ptxP1, ptxA1, prn1, fim3A, and fhaB3) and MT195 genotype and exhibited similar antimicrobial susceptibility profiles. However, despite their simultaneous occurrence, a distinguishable epidemiological link between these isolates could not be established. To gain further insight into the genetic relationship between these isolates in this study, we performed whole-genome analyses. Phylogenetic analysis based on genome-wide single-nucleotide polymorphisms revealed that the isolates belonged to one of the three clades of Chinese MRBP isolates, but there were 11 single-nucleotide polymorphism differences between BP616 and BP625. Genome structure analysis revealed two large inversions (202 and 523 kbp) and one small transposition (3.8 kbp) between the genomes. These findings indicate that the two Japanese MRBP isolates are closely related to Chinese MRBP isolates but are genomically distinct, suggesting that they were introduced into Japan from mainland China through different transmission routes.

Bordetella spp. utilize the type 3 secretion system to manipulate the VIP/VPAC2 signaling and promote colonization and persistence of the three classical Bordetella in the lower respiratory tract

Introduction

Bordetella are respiratory pathogens comprised of three classical Bordetella species: B. pertussis, B. parapertussis, and B. bronchiseptica. With recent surges in Bordetella spp. cases and antibiotics becoming less effective to combat infectious diseases, there is an imperative need for novel antimicrobial therapies. Our goal is to investigate the possible targets of host immunomodulatory mechanisms that can be exploited to promote clearance of Bordetella spp. infections. Vasoactive intestinal peptide (VIP) is a neuropeptide that promotes Th2 anti-inflammatory responses through VPAC1 and VPAC2 receptor binding and activation of downstream signaling cascades.

Methods

We used classical growth in vitro assays to evaluate the effects of VIP on Bordetella spp. growth and survival. Using the three classical Bordetella spp. in combination with different mouse strains we were able to evaluate the role of VIP/VPAC2 signaling in the infectious dose 50 and infection dynamics. Finally using the B. bronchiseptica murine model we determine the suitability of VPAC2 antagonists as possible therapy for Bordetella spp. infections.

Results

Under the hypothesis that inhibition of VIP/VPAC2 signaling would promote clearance, we found that VPAC2-/- mice, lacking a functional VIP/VPAC2 axis, hinder the ability of the bacteria to colonize the lungs, resulting in decreased bacterial burden by all three classical Bordetella species. Moreover, treatment with VPAC2 antagonists decrease lung pathology, suggesting its potential use to prevent lung damage and dysfunction caused by infection. Our results indicate that the ability of Bordetella spp. to manipulate VIP/VPAC signaling pathway appears to be mediated by the type 3 secretion system (T3SS), suggesting that this might serve as a therapeutical target for other gram-negative bacteria.

Conclusion

Taken together, our findings uncover a novel mechanism of bacteria-host crosstalk that could provide a target for the future treatment for whooping cough as well as other infectious diseases caused primarily by persistent mucosal infections.

Molecular Evolution and Increasing Macrolide Resistance of Bordetella pertussis, Shanghai, China, 2016-2022

Resurgence and spread of macrolide-resistant Bordetella pertussis (MRBP) threaten global public health. We collected 283 B. pertussis isolates during 2016-2022 in Shanghai, China, and conducted 23S rRNA gene A2047G mutation detection, multilocus variable-number tandem-repeat analysis, and virulence genotyping analysis. We performed whole-genome sequencing on representative strains. We detected pertussis primarily in infants (0-1 years of age) before 2020 and older children (>5-10 years of age) after 2020. The major genotypes were ptxP1/prn1/fhaB3/ptxA1/ptxC1/fim2-1/fim3-1 (48.7%) and ptxP3/prn2/fhaB1/ptxA1/ptxC2/fim2-1/fim3-1 (47.7%). MRBP increased remarkably from 2016 (36.4%) to 2022 (97.2%). All MRBPs before 2020 harbored ptxP1, and 51.4% belonged to multilocus variable-number tandem-repeat analysis type (MT) 195, whereas ptxP3-MRBP increased from 0% before 2020 to 66.7% after 2020, and all belonged to MT28. MT28 ptxP3-MRBP emerged only after 2020 and replaced the resident MT195 ptxP1-MRBP, revealing that 2020 was a watershed in the transformation of MRBP.

Macrolide Resistance in Bordetella pertussis: Current Situation and Future Challenges

Pertussis is a highly contagious respiratory infection caused by Bordetella pertussis bacterium. The mainstay of treatment is macrolide antibiotics that reduce transmissibility, shorten the duration of symptoms and decrease mortality in infants. Recently, the macrolide resistance of B. pertussis has been reported globally but is especially widespread in mainland China. In this review, we aim to summarise the current understanding of the epidemiology, resistance mechanisms and clinical implications of B. pertussis macrolide resistance. Since the first appearance of macrolide-resistant B. pertussis in Arizona, USA, in 1994, only sporadic cases have been reported outside China. In certain parts of China, on the other hand, up to 70-100% of the recent clinical isolates have been found to be macrolide resistant. Reasons for macrolide resistance being centred upon China during the last decade can only be speculated on, but the dominant B. pertussis lineage is different between China and most of the high-income countries. It seems evident that efforts to increase awareness, guide molecular epidemiological surveillance and carry out systematic screening of B. pertussis positive samples for macrolide resistance should be implemented globally. In addition, practices to improve the clinical care of infants with pertussis caused by resistant strains should be studied vigorously.