An accidental laboratory exposure to Brucella melitensis: the prospective post-exposure management and a detailed investigation into the nature of the exposure

Efficacy of antibiotic prophylaxis to preventing brucellosis in accidental exposure: A systematic review

BACKGROUND

Antibiotic prophylaxis to prevent brucellosis after accidental exposure to Brucella is an important topic in public health. This study aimed to systematically review the efficacy of antibiotic prophylaxis following accidental exposure to Brucella in preventing human brucellosis disease.

METHODS

The study protocol was registered in PROSPERO (CRD42023456812). The outcomes included the incidence of brucellosis disease, adverse events rate, and antibiotic prophylaxis adherence. A comprehensive literature search, conducted until 20 November, 2023, involved Medline, Embase, Cochrane Library, and LILACS databases. Descriptive analysis and meta-analysis using R software were performed, risk of bias was assessed using JBI Critical appraisal tools, and certainty of evidence was assessed using the GRADE tool.

RESULTS

Among 3102 initially identified records, eight studies involving 97 individuals accidentally exposed, all focused on high-risk accidental exposure to Brucella in laboratory settings, were included in the review. All studies reported the prophylactic treatment comprising doxycycline at a dosage of 100 mg twice daily, combined with rifampicin at 600 mg, both administered over 21 days. Prophylaxis adherence was reported in 86% of cases, and incidence of brucellosis post-treatment was 0.01. Adverse events, mainly gastrointestinal, occurred in 26% of cases. Critical appraisal revealed limitations in reporting demographics and clinical information. The certainty of evidence was rated as 'very low,' emphasising the need for caution in interpreting the observed outcomes due to study design constraints and the absence of comparative groups.

CONCLUSIONS

PEP is an alternative practice reported in the literature, used in accidents with high-risk exposure to Brucella. The currently available evidence of the efficacy of antibiotic prophylaxis is insufficient to support a recommendation for or against the widespread use of antibiotic prophylaxis, so caution is needed in interpreting results due to the very low certainty of evidence, primarily stemming from case series and lack of comparative groups.

Molecular characterization and antimicrobial susceptibility testing of clinical and non-clinical Brucella melitensis and Brucella abortus isolates from Egypt

Brucellosis is a highly contagious and incapacitating disease of humans, livestock and wildlife species globally. Treatment of brucellosis in animals is not recommended, and in humans, combinations of antibiotics recommended by the World Health Organization are used. However, sporadic antimicrobial-resistant (AMR) isolates and relapse cases have been reported from different endemic regions. In the current study, molecular characterization and antibiotic susceptibility testing using the microdilution method for 35 B. abortus and B. melitensis strains isolated from humans, milk and animal were carried out. Additionally, Next-Generation-Sequencing (NGS) technology was applied to confirm Brucella at the species level and investigate AMR and pathogenicity-associated determinants. MALDI-TOF seemed to be a rapid and reliable tool for routine identification of brucellae to the genus level; however, DNA-based identification is indispensable for accurate species identification. Brucella abortus strains were isolated from two human cases and a sheep. Such infections are uncommon in Egypt. Egyptian Brucella strains are still in-vitro susceptible to doxycycline, tetracyclines, gentamicin, ciprofloxacin, levofloxacin, chloramphenicol, streptomycin, trimethoprim/sulfamethoxazole and tigecycline. Probable (no CLSI/EUCAST breakpoints have been defined yet) in-vitro resistance to rifampicin and azithromycin was observed. WGS failed to determine classical AMR genes, and no difference in the distribution of virulence-associated genes in all isolates was found. Isolates of human and non-human origins were still susceptible to the majority of antibiotics used for treatment in humans. The absence of classical AMR genes in genomes of “resistant” Brucella strains may reflect a lack of information in databases, or resistance might not be encoded by single resistance genes. The One Health approach is necessary for tackling brucellosis. Continuous susceptibility testing, updating of breakpoints, assessing mutations that lead to resistance are needed.

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Brucella abortus was isolated from human and sheep which is uncommon in Egypt.

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Egyptian Brucella strains are still in-vitro susceptible to majority of antibiotics used for treatment of human brucellosis.

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WGS failed to determine classical AMR genes, and no difference in the distribution of virulence genes in all isolates.

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A combination of DNA-based assays such as PCR or WGS is indispensable in diagnosing Brucella at the species level.

Staggered enforcement of infection control and prevention measures following four consecutive potential laboratory exposures to imported Brucella melitensis

From 2015 until 2020, Brucella melitensis was isolated four times in our microbiology laboratory. All patients had travelled in endemic-areas. Immediately after the first occurrence, all laboratory staff were risk-stratified and preventive and protective measures were applied according to CDC guidelines. Nineteen workers were exposed and needed chemoprophylaxis and follow-up. At each subsequent occurrence, risk analysis was performed, and additional measures were implemented accordingly, leading to a progressive reduction of exposed staff members to none the fourth time. We describe here the additional measures that permitted this important exposure reduction.