---
title: "Macrolide-Resistant Bordetella pertussis Detected in Peru During 2025 Outbreak"
id: "cdc-emerging-infectious-diseases-journal-2-emergence-of-macrolide-resistant-bordetella-pertussis-peru-2025"
canonical_url: "https://medichelpline.com/clinical-feed/cdc-emerging-infectious-diseases-journal-2-emergence-of-macrolide-resistant-bordetella-pertussis-peru-2025"
content_type: "clinical_feed_article"
specialty: "Infectious Disease"
source_name: "CDC Emerging Infectious Diseases Journal"
source_url: "https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article"
published_at: "2026-09-16T04:00:00.000Z"
evidence_level: "Agency Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Macrolide-Resistant Bordetella pertussis Detected in Peru During 2025 Outbreak
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/cdc-emerging-infectious-diseases-journal-2-emergence-of-macrolide-resistant-bordetella-pertussis-peru-2025
- **Specialty:** [Infectious Disease](https://medichelpline.com/clinical-feed/infectious-disease.md)
- **Primary Source:** CDC Emerging Infectious Diseases Journal
- **Source URL:** [Original Journal Publication](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article)
- **Published At:** 2026-09-16T04:00:00.000Z
- **Evidence Rating:** Agency Feed
## Executive GIST (TL;DR)
- The 2025 pertussis outbreak in Peru coincided with the detection of **macrolide-resistant Bordetella pertussis (MRBP)** in clinical samples. Surveillance identified the A2047G 23S rRNA mutation, which confers macrolide resistance. - Researchers screened 68 B. pertussis–positive nasopharyngeal swab samples by direct PCR; 21 samples (31%) carried the **A2047G** mutation. - MRBP infections occurred predominantly in very young infants; 62% of MRBP cases were in infants under 6 months, and MRBP-infected patients were significantly younger than those with macrolide-susceptible strains. - From the 68 samples, seven culture-positive isolates were obtained; all seven isolates were phenotypically resistant to erythromycin and azithromycin and carried the A2047G mutation. - Whole-genome sequencing assigned all seven isolates to sequence type ST2 and clonal complex ST2. Most isolates had the virulence-associated allelic profile ptxP3/ptxA1/ptxB1/ptxC4/fhaB1/fim2-1/fim3-1; one isolate carried ptxP29 with otherwise similar alleles. - All sequenced isolates carried the prn150 allele, a marker of the emerging **MR-MT28** lineage; three isolates showed IS481-mediated prn disruption consistent with pertactin deficiency. - Phylogenetic analysis placed Peruvian MRBP isolates within the MR-MT28 lineage but in at least two distinct sublineages, indicating multiple international introductions rather than a single local emergence. - MRBP cases were geographically dispersed across several Peruvian regions, including Lima, Cusco, Arequipa, Ancash, Loreto, and Puno. - Among patients with treatment data (n = 16), most (14 of 16; 88%) received azithromycin despite resistance being present in isolates. - Peru experienced a marked increase in pertussis incidence from 3.9 cases/1 million in 2023 to 57.5 cases/1 million by August 2025, with 4,976 cumulative cases and 76 deaths recorded by the end of 2025; the Loreto region was disproportionately affected. - The report emphasizes strengthening surveillance for macrolide resistance in pertussis to guide control strategies. - The source text appears truncated in the Conclusions section; additional details beyond the provided text were not reported in the source.
## Clinical Analysis & Structured Key Points
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[EID Journal](https://wwwnc.cdc.gov/eid/) 2. [Volume 32](https://wwwnc.cdc.gov/eid/early-release) 3. [Early Release](https://wwwnc.cdc.gov/eid/early-release#issue-1346) 4. [Main Article](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article) * [Facebook](https://www.facebook.com/sharer/sharer.php?u=%2Feid%2Farticle%2F32%2F10%2F25-1477_article "Share to Facebook") * [Twitter](http://twitter.com/share?url=%2Feid%2Farticle%2F32%2F10%2F25-1477_article&text= "Share to Twitter") * [LinkedIn](https://www.linkedin.com/shareArticle?url=%2Feid%2Farticle%2F32%2F10%2F25-1477_article&title= "Share to LinkedIn") * [Syndicate](https://tools.cdc.gov/medialibrary/index.aspx#/sharecontent//eid/article/32/10/25-1477_article "Embed this Page") [ Emerging Infectious Disease journal ISSN: 1080-6059 ](https://wwwnc.cdc.gov/eid/) _Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released._ #### Volume 32, Number 10—October 2026 ##### _Dispatch_ ### Emergence of Macrolide-Resistant _Bordetella pertussis_ , Peru, 2025 On This Page [The Study](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article) * * * [Conclusions](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article) * * * [Suggested Citation](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article) Figures [Figure 1](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-f1) * * * [Figure 2](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-f2) Tables [Table](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-t1) Downloads [Appendix ](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-app1.pdf) * * * [RIS [TXT - 2 KB] ](https://wwwnc.cdc.gov/eid/article/32/10/25-1477.ris) Article Metrics [Metric Details](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article) Related Articles [_Mycobacterium abscessus_ in Hospital, Maryland](https://wwwnc.cdc.gov/eid/article/32/9/26-0093_article) * * * [Global Spread of _Trichophyton indotineae_](https://wwwnc.cdc.gov/eid/article/32/9/26-0463_article) * * * [Wastewater Surveillance from Healthcare Facilities](https://wwwnc.cdc.gov/eid/article/32/13/25-1490_article) * * * [More articles on Antimicrobial Resistance](https://wwwnc.cdc.gov/eid/spotlight/antimicrobial-resistance) Eduardo Juscamayta-López[![Comments to Author](https://wwwnc.cdc.gov/eid/content/images/icon/email.gif)](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#comment) , Faviola Valdivia, Carmen Rodríguez-Cueva, Helen Horna, Yaneth Quispe, María Pía Soto, Segundo Torres, Victor Fiestas Solórzano, Martin Yagui, Vlademir Vicente Cantarelli, Efrain Montilla-Escudero, Víctor Silva, and Ana Raquel Da Costa Author affiliation: Instituto Nacional de Salud, Lima, Peru (E. Juscamayta-López, F. Valdivia, C. Rodríguez-Cueva, H. Horna, Y. Quispe, M. Pía Soto, S. Torres, V. Fiestas Solórzano, M. Yagui); American Society for Microbiology, Washington DC, USA (V. Vicente Cantarelli, E. Montilla-Escudero, V. Silva, A. Raquel Da Costa). [Suggested citation for this article](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#suggestedcitation) ### Abstract We report the emergence of macrolide-resistant Bordetella pertussis during a pertussis outbreak in Peru. Among 68 cases, 31% carried the A2047G gene mutation, conferring resistance to macrolides. Whole-genome sequencing revealed 2 genetically distinct groups, indicating multiple introductions into Peru. Our findings support strengthening surveillance for macrolide-resistant pertussis to inform control strategies. The bacterium _Bordetella pertussis_ is the causative agent of pertussis, a highly contagious respiratory infection, which poses the greatest risk for severe illness and death in infants ([_1_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r1 "1")). Despite widespread vaccination, there is a global resurgence of pertussis and a large increase in cases reported after the COVID-19 pandemic ([_2_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r2 "2")). The pertussis resurgence is likely multifactorial, including declining vaccination coverage, improved diagnostic capacity, waning immunity, and the evolutionary adaptation of _B. pertussis_ bacteria ([_3_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r3 "3")). Macrolide antimicrobial drugs are the first-line pertussis treatment because of their effectiveness in reducing bacterial carriage and transmission, curtailing the duration of symptoms, and lowering the risk for infant death ([_4_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r4 "4")). However, macrolide-resistant _B. pertussis_ (MRBP), primarily associated with the A2047G mutation in 23S rRNA genes, has emerged globally ([_5_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r5 "5")). The highest prevalence of MRBP has been reported in China ([_6_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r6 "6")), whereas reports of MRBP from Latin America remain scarce ([_7_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r7 "7")). In 2025, the Peruvian Ministry of Health reported the largest pertussis outbreak in decades in the country. Although precisely defining the onset of the outbreak is challenging, surveillance data suggest that transmission intensified in 2024. National incidence increased from 3.9 cases/1 million inhabitants in 2023 to 7.4 cases/1 million inhabitants in 2024 and reached 57.5 cases/1 million inhabitants by August 2025 ([_8_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r8 "8")). A cumulative total of 4,976 cases ([Appendix](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-app1.pdf) Figure) and 76 deaths were recorded by the end of 2025. The effects were concentrated in the Loreto region, which accounted for 3,922 cases and 57 deaths, disproportionately affecting Indigenous communities in Datem del Marañón, where pertussis vaccine coverage remains suboptimal ([_9_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r9 "9"),[_10_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r10 "10")). Peru’s national immunization schedule includes 3 primary doses of the pentavalent diphtheria–tetanus–whole cell pertussis–hepatitis B– _Hemophilus influenzae_ type b vaccine (DTwP-HepB-Hib) at 2, 4, and 6 months of age, followed by DTwP boosters at 18 months and 4 years of age, and tetanus–diphtheria–acellular pertussis vaccination during pregnancy, recommended at 20–36 weeks of gestation. To determine _B. pertussis_ transmission dynamics in Peru, we detected and characterized MRBP from _B. pertussis_ –positive swab samples. ### The Study Figure 1 ![Geographic distribution of confirmed pertussis cases and MRBP cases in Peru, 2025. Regional shading shows cumulative confirmed pertussis cases since epidemiologic week 53 of 2025; darker blue indicates higher case counts. Purple circles indicate regions where patients carrying B. pertussis strains with the macrolide resistance–associated A2047G mutation were detected. MRBP, macrolide-resistant Bordetella pertussis.](https://wwwnc.cdc.gov/eid/images/25-1477-F1-tn.jpg) [Figure 1](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-f1 "Figure 1"). Geographic distribution of confirmed pertussis cases and MRBP cases in Peru, 2025. Regional shading shows cumulative confirmed pertussis cases since epidemiologic week 53 of 2025; darker blue indicates higher case... In early 2025, we screened for MRBP in _B. pertussis_ –positive nasopharyngeal swab samples from 68 patients ([_11_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r11 "11")) (median 3 months of age; range 1 month–39 years of age) by using direct PCR ([Appendix](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-app1.pdf) Table 1) targeting the A2047G mutation in the 23S rRNA genes. We detected the A2047G mutation in 21 (31%) of 68 samples. Patients infected with MRBP were significantly younger (median 3.6 vs 36.1 months of age; p = 0.007) than patients infected with macrolide-susceptible _B. pertussis_ strains. However, we observed no significant differences in patient sex or vaccination status between the 2 groups ([Appendix](https://wwwnc.cdc.gov/eid/article/32/10/25-1477-app1.pdf) Table 2). Most MRBP infections were in infants 2 genetically distinct MR-MT28 sublineages, including PG1-associated pertactin-deficient isolates, consistent with the ongoing international diversification and dissemination of this lineage. Consistent with recent global genomic analyses, the close phylogenetic relationship between the 7 isolates from Peru and contemporary MR-MT28 strains is consistent with the ongoing international dissemination and diversification of this lineage ([_5_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r5 "5"),[_13_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r13 "13")). The presence of 2 genetically distinct MR-MT28 groups circulating in Peru suggests multiple international introductions of MRBP into Peru, rather than a single transmission event. Pertactin-deficient isolates have predominantly been reported in countries using acellular pertussis vaccines, where loss of pertactin is considered an adaptive response to vaccine-induced immune pressure ([_5_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r5 "5"),[_13_](https://wwwnc.cdc.gov/eid/article/32/10/25-1477_article#r13 "13")). Alth
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