A citywide, clonal outbreak of Pseudomonas aeruginosa

Int J Infect Dis. 2022 Apr:117:74-86. doi: 10.1016/j.ijid.2022.01.039. Epub 2022 Jan 22.

Abstract

Background: Outbreaks of community-acquired Pseudomonas aeruginosa are typically small and localized. We investigated an increase in community-acquired infections with P. aeruginosa in Cape Town, South Africa.

Methods: Cases were defined as P. aeruginosa isolated from any clinical sample, and "wild-type" as those susceptible to all antibiotics tested. The residential addresses of community-acquired wild-type cases were mapped. Whole-genome sequencing and multilocus sequence typing were used to determine clonality and identify virulence genes. A clinical study in a subset of patients with bloodstream infection compared demographic and clinical characteristics between sequence types (STs).

Results: The outbreak lasted 10 months from December 2016 to September 2017 with 3,321 documented cases. At the peak, cases reached 2.3-fold baseline rates. Cases were distributed widely across the city. Multilocus ST 303 was predominant during the outbreak. A total of 51 virulence genes were differentially present in ST303 compared with other STs, including genes involved in biofilm formation, iron uptake, and gut penetration.

Conclusion: The investigation confirmed a citywide outbreak of P. aeruginosa. We identified a predominant outbreak-associated clone, ST303, which harbored genes that could contribute to virulence and survival in adverse environmental conditions such as those associated with drought.

Keywords: Cape Town; Pseudomonas aeruginosa; clone; drought; outbreak.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Disease Outbreaks
  • Humans
  • Multilocus Sequence Typing
  • Pseudomonas Infections* / epidemiology
  • Pseudomonas aeruginosa* / genetics
  • South Africa / epidemiology

Substances

  • Anti-Bacterial Agents