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Updated: Oct 5, 2025
Replication of the Ordered, Nonredundant Library of Pseudomonas aeruginosa strain PA14 Transposon Insertion Mutants
Published on: May 4, 2018
A citywide, clonal outbreak of Pseudomonas aeruginosa
Christoffel J Opperman1, Clinton Moodley2, Katie Lennard3
1Division of Medical Microbiology, University of Cape Town, and National Health Laboratory Service, Groote Schuur Hospital, Green Point Laboratory, Cape Town, South Africa.
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.
Insights
A large Pseudomonas aeruginosa outbreak occurred in Cape Town, South Africa, infecting 3,321 people over 10 months. A specific clone, ST303, was identified as the primary cause, possessing genes for enhanced virulence.
Area of Science:
- Medical Microbiology
- Infectious Disease Epidemiology
- Genomic Epidemiology
Background:
- Community-acquired Pseudomonas aeruginosa infections are usually localized.
- An unusual increase in P. aeruginosa infections was observed in Cape Town, South Africa.
Purpose of the Study:
- To investigate a citywide outbreak of community-acquired Pseudomonas aeruginosa infections.
- To identify the predominant clone and its virulence factors associated with the outbreak.
Main Methods:
- Defined cases and wild-type P. aeruginosa strains.
- Mapped residential addresses of community-acquired wild-type cases.
- Utilized whole-genome sequencing and multilocus sequence typing to analyze clonality and virulence genes.
Main Results:
- The outbreak spanned 10 months (December 2016-September 2017) with 3,321 cases, peaking at 2.3 times baseline rates.
- Cases were widespread across Cape Town.
- Multilocus sequence type 303 (ST303) was predominant, carrying 51 differentially present virulence genes, including those for biofilm formation and gut penetration.
Conclusions:
- Confirmed a citywide Pseudomonas aeruginosa outbreak in Cape Town.
- Identified ST303 as the primary outbreak clone.
- ST303 possesses genes potentially enhancing virulence and survival in harsh environments, like drought conditions.
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