The burden of invasive bacterial infections in Pemba, Zanzibar

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Public Health Surveillance

Background:

• A surveillance study was conducted in Pemba Island, Zanzibar, to identify bloodstream infection causes in febrile patients.
• The study focused on an area with historically low malaria transmission rates.

Purpose of the Study:

• To determine the predominant bacterial pathogens responsible for bloodstream infections.
• To assess the incidence of Salmonella Typhi and Streptococcus pneumoniae infections.
• To evaluate antimicrobial resistance patterns, particularly multidrug resistance (MDR).

Main Methods:

• Blood samples were collected from febrile patients over two months old presenting at three district hospitals.
• Microbiologic cultures and malaria testing were performed on all collected blood samples.
• Crude and adjusted incidence rates for bacterial sepsis and malaria were calculated.

Main Results:

• Out of 2,209 blood cultures, 79 (4%) yielded pathogenic bacteria, with Salmonella Typhi (58%) and Streptococcus pneumoniae (15%) being most common.
• Adjusted incidence rates for Salmonella Typhi and Streptococcus pneumoniae infections were high.
• Significant antimicrobial resistance was observed, with 42% of Salmonella Typhi isolates exhibiting multidrug resistance to ampicillin, chloramphenicol, and cotrimoxazole.

Conclusions:

• Salmonella Typhi and Streptococcus pneumoniae are significant causes of febrile bloodstream infections in Pemba Island, Zanzibar, despite low malaria incidence.
• High rates of multidrug-resistant Salmonella Typhi necessitate urgent public health attention.
• Preventive strategies, including vaccination, are recommended to reduce the burden of febrile illnesses.