Exploration of risk factors for ceftriaxone resistance in invasive non-typhoidal Salmonella infections in western Kenya

Developing a clinical prediction model to modify empirical antibiotics for non-typhoidal Salmonella bloodstream infection in children under-five in the Democratic Republic of Congo

BACKGROUND

Non-typhoidal Salmonella (NTS) frequently cause bloodstream infection in children under-five in sub-Saharan Africa, particularly in malaria-endemic areas. Due to increasing drug resistance, NTS are often not covered by standard-of-care empirical antibiotics for severe febrile illness. We developed a clinical prediction model to orient the choice of empirical antibiotics (standard-of-care versus alternative antibiotics) for children admitted to hospital in settings with high proportions of drug-resistant NTS.

METHODS

Data were collected during a prospective cohort study in children (> 28 days-< 5 years) admitted with severe febrile illness to Kisantu district hospital, DR Congo. The outcome variable was blood culture confirmed NTS bloodstream infection; the comparison group were children without NTS bloodstream infection. Predictors were selected a priori based on systematic literature review. The prediction model was developed with multivariable logistic regression; a simplified scoring system was derived. Internal validation to estimate optimism-corrected performance was performed using bootstrapping and net benefits were calculated to evaluate clinical usefulness.

RESULTS

NTS bloodstream infection was diagnosed in 12.7% (295/2327) of enrolled children. The area under the curve was 0.79 (95%CI: 0.76-0.82) for the prediction model, and 0.78 (0.85-0.80) for the scoring system. The estimated calibration slopes were 0.95 (model) and 0.91 (scoring system). At a decision threshold of 20% NTS risk, the prediction model and scoring system had 57% and 53% sensitivity, and 85% specificity. The net benefit for decisions thresholds < 30% ranged from 2.4 to 3.9 per 100 children.

CONCLUSION

The model predicts NTS bloodstream infection and can support the choice of empiric antibiotics to include coverage of drug-resistant NTS, in particular for decision thresholds < 30%. External validation studies are needed to investigate generalizability.

TRIAL REGISTRATION

DeNTS study, clinicaltrials.gov: NCT04473768 (registration 16/07/2020) and TreNTS study, clinicaltrials.gov: NCT04850677 (registration 20/04/2021).

The prevalence of antimicrobial drug resistance of non-typhoidal Salmonella in human infections in sub-Saharan Africa: a systematic review and meta-analysis

INTRODUCTION

Non-typhoidal Salmonella (NTS) bacteremia is common in sub-Saharan Africa. We examined the prevalence of antibiotic resistance to fluoroquinolones, third-generation cephalosporins, and multi-drug resistance (MDR) in NTS human isolates from sub-Saharan Africa.

METHODS

A systematic review was conducted using a search in Ovid Medline, Embase, and African Index Medicus of publications between 2000 and 2021. A random-effects model meta-analysis was performed using data from 66 studies that included 29,039 NTS blood and 1,065 stool isolates.

RESULTS

The pooled prevalence proportions of MDR were 0.685 (95% CI 0.574-0.778) and 0.214 (0.020-0.785) in blood vs. stool isolates. The corresponding estimates of fluoroquinolones resistance were 0.014 (0.008-0.025) vs. 0.021 (0.012-0.036) and third-generation cephalosporins resistance 0.019 (0.012-0.031) vs. 0.035 (0.006-0.185). Similar results were found for children and adults. Resistance prevalence to these antibiotics in blood isolates increased between 2000-2010 and 2011-2021. The guidelines employed to determine antimicrobial resistance and epidemiological characteristics (e.g. sample size, study duration) correlated with the resistance prevalence.

CONCLUSIONS

The prevalence of MDR and resistance to fluoroquinolones and third-generation cephalosporins in NTS in sub-Saharan Africa is alarming.

EXPERT OPINION

Standardized surveillance of antimicrobial drug resistance in NTS in sub-Saharan Africa is warranted to guide healthcare policymaking and antibiotic stewardship programs.

Antimicrobial Resistance in endemic enteric infections in Kenya and the region, and efforts towards addressing the challenges

Resistance to commonly available antimicrobials is a major threat to the fight against endemic bacterial diseases in sub-Saharan Africa, with a majority of the population unable to afford alternative effective antimicrobial options for management of these diseases. Diseases such as typhoid, cholera, and invasive nontyphoidal Salmonella are among the key enteric infections endemic in most parts of sub-Saharan Africa, especially in displaced populations and among the urban populations living in overcrowded informal settlements. Here, we explore the prevalence and the genomic epidemiology of these infections and the growing problem of multidrug resistance, including emerging resistance to the last line of treatment for these infections. Prevalence rates to commonly available antimicrobials, including ampicillin, chloramphenicol, cotrimoxazole, and tetracycline, now range between 65% and 80%, while 15%–20% of recently studied isolates show reduced susceptibility to fluoroquinolones and emerging resistance to extended-spectrum β-lactams mediated by the CTX-M-15 gene carried on a highly mobile genetic element. The high prevalence of multidrug-resistant isolates including resistance to reserve antibiotics, calls for enhanced control and management options. It will be important for governments in the region to enhance the implementation of national action plans, as guided by the global action plan championed by the World Health Organization, to combat the threat of antimicrobial resistance. However, to yield meaningful results, these efforts will require a strong commitment and enhancement at all levels of healthcare in order. In addition, the use of World Health Organization–approved vaccines in the short to medium term and improvement of water and sanitation in the long term will reduce the burden of disease and antimicrobial resistance in the region.

Revisiting Co-trimoxazole Prophylaxis for African Adults in the Era of Antiretroviral Therapy: A Randomized Controlled Clinical Trial

BACKGROUND

Daily co-trimoxazole is recommended for African adults living with human immunodeficiency virus (HIV) irrespective of antiretroviral treatment, immune status, or disease stage. Benefits of continued prophylaxis and whether co-trimoxazole can be stopped following immune reconstitution are unknown.

METHODS

We conducted a randomized controlled trial at 2 sites in Malawi that enrolled adults with HIV with undetectable viral load and CD4 count of >250/mm3 and randomized them to continue daily co-trimoxazole, discontinue daily co-trimoxazole and begin weekly chloroquine, or discontinue daily co-trimoxazole. The primary endpoint was the preventive effect of co-trimoxazole prophylaxis against death or World Health Organization (WHO) HIV/AIDS stage 3-4 events, using Cox proportional hazards modeling, in an intention-to-treat population.

RESULTS

1499 adults were enrolled. The preventive effect of co-trimoxazole on the primary endpoint was 22% (95% CI: -14%-47%; P = .20) versus no prophylaxis and 25% (-10%-48%; P = .14) versus chloroquine. When WHO HIV/AIDS stage 2 events were added to the primary endpoint, preventive effect increased to 31% (3-51%; P = .032) and 32% (4-51%; P = .026), respectively. Co-trimoxazole and chloroquine prophylaxis effectively prevented clinical malaria episodes (3.8 and 3.0, respectively, vs 28/100 person-years; P < .001).

CONCLUSIONS

Malawian adults with HIV who immune reconstituted on ART and continued co-trimoxazole prophylaxis experienced fewer deaths and WHO HIV/AIDS stage 3-4 events compared with prophylaxis discontinuation, although statistical significance was not achieved. Co-trimoxazole prevented a composite of death plus WHO HIV/AIDS stage 2-4 events. Given poor healthcare access and lack of routine viral load monitoring, co-trimoxazole prophylaxis should continue in adults on ART after immune reconstitution in sub-Saharan Africa. Clinical Trials Registration. NCT01650558.

Salmonella Bloodstream Infections in Hospitalized Children with Acute Febrile Illness-Uganda, 2016-2019

Invasive Salmonella infection is a common cause of acute febrile illness (AFI) among children in sub-Saharan Africa; however, diagnosing Salmonella bacteremia is challenging in settings without blood culture. The Uganda AFI surveillance system includes blood culture-based surveillance for etiologies of bloodstream infection (BSIs) in hospitalized febrile children in Uganda. We analyzed demographic, clinical, blood culture, and antimicrobial resistance data from hospitalized children at six sentinel AFI sites from July 2016 to January 2019. A total of 47,261 children were hospitalized. Median age was 2 years (interquartile range, 1-4) and 26,695 (57%) were male. Of 7,203 blood cultures, 242 (3%) yielded bacterial pathogens including Salmonella (N = 67, 28%), Staphylococcus aureus (N = 40, 17%), Escherichia spp. (N = 25, 10%), Enterococcus spp. (N = 18, 7%), and Klebsiella pneumoniae (N = 17, 7%). Children with BSIs had longer median length of hospitalization (5 days versus 4 days), and a higher case-fatality ratio (13% versus 2%) than children without BSI (all P < 0.001). Children with Salmonella BSIs did not differ significantly in length of hospitalization or mortality from children with BSI resulting from other organisms. Serotype and antimicrobial susceptibility results were available for 49 Salmonella isolates, including 35 (71%) non-typhoidal serotypes and 14 Salmonella serotype Typhi (Typhi). Among Typhi isolates, 10 (71%) were multi-drug resistant and 13 (93%) had decreased ciprofloxacin susceptibility. Salmonella strains, particularly non-typhoidal serotypes and drug-resistant Typhi, were the most common cause of BSI. These data can inform regional Salmonella surveillance in East Africa and guide empiric therapy and prevention in Uganda.