An unusual case of seronegative, 16S PCR positive Brucella infection

Bharathan, Binutha; Backhouse, Lucy; Rawat, David; Naik, Sandhia; Millar, Michael

doi:10.1099/jmmcr.0.005050

Cited by 4 publications

(5 citation statements)

References 21 publications

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“…Of note, the majority (77%, n = 17) of those who had Brucella spp DNA detected did not have detectable antibodies by either serological assay. [23,24]. Diagnosis of brucellosis is complex and confirmatory diagnosis is made by Brucella culture or achieved through a series of serological tests.…”

Section: Discussionmentioning

confidence: 99%

“…There is the likelihood that some of these 17 sero-negative, Brucella PCR-positive individuals are infected with a rough Brucella species such as Brucella canis, that does not cross react with standard diagnostic agglutination and ELISA tests using capture antigen that only detects antibody from smooth Brucella strains [34]. Additionally, though rare, there have been case reports of sero-negative and culture positive or PCR-positive brucellosis cases [23,24,35]. In clinical settings, case management decisions surrounding such diagnostic results are challenging.…”

Section: Plos Neglected Tropical Diseasesmentioning

confidence: 99%

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High incidence of human brucellosis in a rural Pastoralist community in Kenya, 2015

et al. 2021

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Background Brucellosis occurs globally with highly variable incidence in humans from very low in North America and Western Europe to high in the Middle East and Asia. There are few data in Sub-Saharan Africa. This study estimated the incidence of human brucellosis in a pastoralist community in Kenya. Methods Between February 2015 and January 2016, we enrolled persons living in randomly selected households in Kajiado County. Free health care was offered at three facilities in the study area. Those who met the study clinical case definition completed a standardized questionnaire on demographics, clinical history and presentation. A blood sample was collected and tested by Rose Bengal test (RBT), then later tested at the Kenya Medical Research Institute laboratory for Brucella IgG and IgM by ELISA. Those who tested positive by both RBT and ELISA (IgG or IgM antibodies) were classified as confirmed while those that only tested positive for IgG or IgM antibodies were classified as probable. Further, sera were tested by polymerase chain reaction using a TaqMan Array Card (TAC) for a panel of pathogens causing AFI including Brucella spp. Annual incidence of brucellosis was calculated as the number of confirmed cases in one year/total number in the study population. Results We enrolled a cohort of 4746 persons in 804 households. Over half (52.3%) were males and the median age was 18 years (Interquartile range (IQR) 9 months– 32 years). A total of 236 patients were enrolled at three health facilities; 64% were females and the median age was 40.5 years (IQR 28–53 years). Thirty-nine (16.5%) were positive for Brucella antibodies by IgG ELISA, 5/236 (2.1%) by IgM ELISA and 4/236 (1.7%) by RBT. Ten percent 22/217 were positive by TAC. We confirmed four (1.7%) brucellosis cases giving an annual incidence of 84/100,000 persons/year (95% CI 82, 87). The incidence did not significantly vary by gender, age and location of residence. Conclusion We report a high incidence of brucellosis in humans among members of this pastoralist community. Brucellosis was the most common cause febrile illness in this community.

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Section: Discussionmentioning

confidence: 99%

Section: Plos Neglected Tropical Diseasesmentioning

confidence: 99%

High incidence of human brucellosis in a rural Pastoralist community in Kenya, 2015

et al. 2021

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“…As one might expect from a molecular diagnostic assay, a number of non-culturable or fastidious organisms are detected (). These organisms are very rarely (or in some cases never) identified in the clinical microbiology laboratory using culture-based methods [3–6]. Molecular diagnostic techniques are only applied to selected specimens in a limited number of laboratories, therefore the true incidence of such pathogens as the causative agents of infection may be much higher.…”

Section: Discussionmentioning

confidence: 99%

“…Molecular techniques are used in the clinical bacteriology laboratory to support culture-based methodologies; for instance, PCR-based assays are employed to detect pathogens that prove difficult (or impossible) to culture, a common scenario in patients whose infections are treated empirically with antibiotics [1, 2]. Additionally, they are useful for detecting fastidious or slow-growing bacterial pathogens [3–6]. This is in contrast to the clinical virology laboratory, where PCR and other molecular diagnostic methods have revolutionised the speed and sensitivity of testing for viral infections, replacing viral culture [7].…”

Section: Introductionmentioning

confidence: 99%

Diagnostic yield of broad-range 16s rRNA gene PCR varies by sample type and is improved by the addition of qPCR panels targeting the most common causative organisms

Harris

Brown

2022

Journal of Medical Microbiology

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Introduction. Molecular techniques are used in the clinical microbiology laboratory to support culture-based diagnosis of infection and are particularly useful for detecting difficult to culture bacteria or following empirical antimicrobial treatment. Hypothesis/Gap Statement. Broad-range 16S rRNA PCR is a valuable tool that detects a wide range of bacterial species. Diagnostic yield is low for some sample types but can be improved with the addition of qPCR panels targeting common bacterial pathogens. Aim. To evaluate the performance of a broad-range 16S rRNA gene PCR and the additional diagnostic yield of targeted qPCR applied to specimens according to a local testing algorithm. Methodology. In total, 6130 primary clinical samples were collected as part of standard clinical practice from patients with suspected infection during a 17 month period. Overall, 5497 samples were tested by broad-range 16S rRNA gene PCR and a panel of targeted real-time qPCR assays were performed on selected samples according to a local testing algorithm. An additional 633 samples were tested by real-time qPCR only. The 16S rRNA gene PCR was performed using two assays targeting different regions of the 16S rRNA gene. Laboratory developed qPCR assays for seven common bacterial pathogens were also performed. Data was extracted retrospectively from Epic Beaker Laboratory Information Management System (LIMS). Results. Broad-range 16S rRNA gene PCR improves diagnostic yield in culture-negative samples and detects a large range of bacterial species. Streptococcus spp., Staphylococcu s spp. and the Enterobacteriaceae family are detected the most frequently in samples with a single causative organism, but mixed samples frequently contained anaerobic species. The highest diagnostic yield was obtained from abscess, pus and empyema samples; 44.9 % were positive by 16S and 61 % were positive by the combined 16S and targeted qPCR testing algorithm. Samples with a particularly low diagnostic yield were blood, with 3.3 % of samples positive by 16S and CSF with 4.8 % of samples positive by 16S. The increased diagnostic yield of adding targeted qPCR is largest (~threefold) in these two sample types. Conclusion. Broad-range PCR is a powerful technique that can detect a very large range of bacterial pathogens but has limited diagnostic sensitivity. The data in this report supports a testing strategy that combines broad-range and targeted bacterial PCR assays for maximizing diagnosis of infection in culture-negative specimens. This is particularly justified for blood and CSF samples. Alternative approaches, such as metagenomic sequencing, are needed to provide the breadth of broad-range PCR and the sensitivity of targeted qPCR panels.

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“…CNS-specific immunological reaction due to persistent antigenic local stimulation could be the case in seronegative individuals, and has been shown to result in intrathecal IgG synthesis and consequent positive CSF oligoclonal bands (OCBs) in chronic neurobrucellosis patients (Bucher et al, 1990, Daif, 1991. More recently, molecular techniques such as 16S rRNA sequencing and next-generation sequencing have also been used in cases where a diagnosis of neurobrucellosis is challenging (Fan et al, 2018, Renard et al, 2006, Valenza et al, 2006, as well as in cases of seronegative organ-specific brucellosis (Bharathan et al, 2016). We argue for the need of establishing neurobrucellosis diagnostic criteria, presenting a case of a seronegative relapse of neurobrucellosis that was diagnosed after advanced immunological and molecular testing in the CSF.…”

Section: Introductionmentioning

confidence: 99%

Seronegative neurobrucellosis—do we need new neurobrucellosis criteria?

Papadopoulos

Patas

Tountopoulou

et al. 2021

International Journal of Infectious Diseases

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An unusual case of seronegative, 16S PCR positive Brucella infection

Cited by 4 publications

References 21 publications

High incidence of human brucellosis in a rural Pastoralist community in Kenya, 2015

High incidence of human brucellosis in a rural Pastoralist community in Kenya, 2015

Diagnostic yield of broad-range 16s rRNA gene PCR varies by sample type and is improved by the addition of qPCR panels targeting the most common causative organisms

Seronegative neurobrucellosis—do we need new neurobrucellosis criteria?

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