The first human case report of molecularly confirmed co-infection of Brucella melitensis and Coxiella burnetii: A case report

Co-infection with Brucella melitensis and Coxiella burnetii has been rarely reported. To date, there are only two co-infection case reports from Croatia and China which diagnosed the infections mainly through the use of serological tests. In this report, we present the first case of molecularly confirmed B. melitensis bacteremia and C. burnetii spondylodiscitis co-infection in a goat dairy farmer who presented with lumbosacral spondylodiscitis and bilateral psoas abscesses. From the blood culture, B. melitensis was identified by using 16S rRNA gene sequencing and specific PCR. Lumbar bone tissue was found to be positive for C. burnetii using multiplex real-time PCR and was confirmed with a positive result from conventional PCR which detected the infection through the identification of the IS1111 gene. The patient's condition improved after decompressive laminectomy was performed and administration of antibiotics regimen: intravenous gentamicin, oral rifampicin, and oral doxycycline. From our case, it is important to raise awareness of this underreported co-infection with multiple zoonotic diseases, especially Q fever and brucellosis, which share the same exposure risk. Moreover, we also emphasize the use of advanced molecular techniques to improve the diagnostic efficiency and reduce the use of time-consuming procedures among patients who are continuously exposed to such risk factors in areas with high seroprevalence of these zoonotic diseases.

Immunogenicity and safety of heterologous versus homologous prime-boost schedules with inactivated and adenoviral vectored SARS-CoV-2 vaccines - A prospective multi-center study

Background

During the peak of Coronavirus disease (COVID-19) pandemic in Thailand when the emergence of delta variant reduced the efficacy of inactivated vaccine, Thailand had abundance of inactivated vaccine but mRNA vaccine was not available and the supply of adenoviral-vectored vaccine was limited. The heterologous vaccination using CoronaVac and ChAdOx1-nCoV-19 vaccines was applied. We aim to compare the immunogenicity of immune response of primary vaccination with homologous ChAdOx1 nCoV-19 and heterologous vaccination with CoronaVac and ChAdOx1 nCoV-19.

Methods

A total of 430 adults, scheduled to receive ChAdOx1-nCoV-19 as their second dose of primary COVID-19 vaccination, were enrolled. Participants were classified into two groups based on the first dose vaccine as CoronaVac (heterologous group) or ChAdOx1 nCoV-19 (homologous group). The primary outcome was antibodies to the SARS-CoV-2 spike protein receptor binding domain (anti-RBD) titres at 28 days after the second dose of vaccination. Secondary outcomes were anti-RBD titres at 90 days, surrogate viral neutralizing test (sVNT) at 28 and 90 days, and adverse events.

Findings

In 358 participants with correct vaccine interval, the anti-RBD geometric mean titre ratio for the heterologous versus homologous group was 0.55 (95%CI; 0.44-0.067); p < 0.001 at day 28, and 0.80 (95%CI; 0.65-1.00); P = 0.05 at day 90. Median sVNT neutralizing activity was not significantly different in the heterologous versus homologous group at 28 days (93.5 vs 92.7 %); p = 0.13, but significantly higher in the heterologous group at day 90 (82.9 vs 76.4 %); p = 0.01.

Interpretation

The homologous vaccination resulted in higher anti-RBD titres at 28 days after vaccination, but titres in the homologous group showed more rapid decline at 90 days. In the sVNT assay, median neutralization was similar at 28 days, but was longer-lasting and higher in the heterologous group at 90 days.

Funding

This research received funding from the Royal College of Physicians of Thailand special grant 2021 for research initiative during COVID-19 pandemic.

1421. A 5-year Review of Mycobacterium abscessus Susceptibility in a Tertiary Hospital in Thailand

Background

Mycobacterium abscessus is a common rapid growing mycobacteria (RGM). It causes chronic nodular or cavitary lung disease in adults with bronchiectasis or cystic fibrosis, skin and soft tissue infection following penetrating injury or an unsterile skin procedure. It was also a pathogen of disseminated infection in patients with anti-interferon-gamma autoantibodies. The 2018 clinical and laboratory standards institute (CLSI) guideline suggested that amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem, linezolid, meropenem, moxifloxacin, trimethoprim-sulfamethoxazole, tigecycline and tobramycin should be tested against RGM. We aimed to review the antimicrobial susceptibility of this organism in our hospital.

Methods

We performed a retrospective descriptive review of the minimal inhibitory concentration (MIC) of clinical isolates of M. abscessus from 2013 to 2018.

Results

We found 267 isolates of M. abscessus. Eighty-four isolates were tested for MICs. Of these, 4 isolates were excluded due to duplication. The remaining 80 isolates were included for analysis. The susceptibility results were as follows.

Conclusion

To our knowledge, this is the largest report of susceptibility pattern of M. abscessus in Thailand. MICs of cefoxitin and imipenem, which are the recommended intravenous antimicrobials, were high. Most isolates also demonstrated high MICs of doxycycline, linezolid, trimethoprim-sulfamethoxazole, tobramycin, ciprofloxacin and moxifloxacin. In contrast, most of MICs of amikacin and clarithromycin were in susceptible range. These findings may be used to guide the treatment regimen although clinical outcomes of each drug are still to be investigated.

Disclosures

All Authors: No reported disclosures.