Brucella Reference Laboratory

[Cary Polachek]

Thelaboratory uses a range of commercial CE-marked and both in-house assays to detect both total IgG, IgM and specific IgG and IgM brucella antibodies. All sera are screened using a CE-marked total brucella antibody assay and specific IgG/IgM enzyme immunoassays. Screen positive samples undergo further testing with an in-house micro-agglutination assay.

If the serology titres suggest possible active infection, samples are tested for Brucella PCR. This test is a pan-genus assay and is unable to differentiate between species of Brucella. A minimum of 500ul of serum is required.

The screening tests used at BRU are very sensitive (low false negative rates). However, if there is a strong clinical suspicion of brucellosis, it is good practice to repeat the test after a 6 week period.

Approximately 95% of sera received by BRU are seronegative in all screening tests. The remaining 5% of brucellosis serology results need to be interpreted with caution because of possible false negative results (in early infection) or false positive results (due to prior exposure).

The BRU does not provide a culture confirmation service, but collaborates closely with the OIE/FAO Reference Laboratory for Brucellosis at the Animal and Plant Health Agency (APHA) in Surrey, to whom all suspect culture isolates should be sent.

For further information on the referral of suspected Brucella cultures or clinical material, please contact the Brucella Reference Laboratory by email at Brucel...@apha.gov.uk or by telephone on 0330 041 6562.

This is a very rare condition in the UK. Negative serology should exclude the diagnosis so always send a serum sample in the first instance. Cerebrospinal fluid (CSF) will only be examined for Brucella antibody if there is evidence of Brucella seroreactivity in serum.

Brucella canis is the cause of brucellosis in dogs. It is not usually present in British dogs but may occur in dogs imported from other countries. The origin and travel history of implicated animals should be checked.

This species of Brucella lacks surface lipopolysaccharide (LPS) and therefore will elicit a minimal anti-LPS immunological response, hence suspected B. canis infection will not be identified by standard Brucella antibody screening tests. Consequently, B. canis serology should be specifically requested on the request form if infection due to this species is suspected.

Two Brucella species, B. ceti and B. pinnipedialis, have been isolated from marine mammals. Cetaceans (dolphins and similar animals), seals and sea lions are the preferred hosts. A few human cases have been reported with naturally acquired infection with marine species of Brucella.

No precautions specific to these species can currently be advised, however brucellosis should be considered if the patient becomes unwell after exposure. It is important to note that our serology tests may not detect marine brucellosis species.

Management should always be overseen by a consultant paediatrician with a specialist interest in infectious diseases. In the absence of randomised controlled trials, the guidance published by the American Academy of Paediatrics is recommended. This includes dosage guidance:

Staff in routine diagnostic laboratories are not normally considered to be at risk of infection with Brucella. Blood from patients with brucellosis will have a very low level bacteraemia and should not pose a risk during routine processing in haematology, clinical chemistry or blood sciences laboratories. Rare instances of high risk exposures such as a blood conjunctival splash might require discussion with BRU. Otherwise, staff do not need monitoring or testing.

when brucellosis is suspected, clinicians should note the suspicion of brucellosis on the laboratory request form; however, as clinical details are often insufficient to identify high risk specimens when received in the laboratory, all blood cultures should be assessed for risk of Category 3 organisms and handled appropriately

almost all Brucella isolates in the UK over the past 5 years have been isolated only from blood culture; that is why all unusual small Gram-negative or Gram-variable rods from blood culture which are either oxidase positive or urease positive, or both, should be examined in a containment level 3 facility using a Class I biosafety cabinet

note that current laboratory identification methods (such as API, VITEK, MALDI-TOF) may not give reliable identification of suspect isolates with both false positive and false negative results occurring; all suspect isolates should be confirmed at the APHA reference laboratory

Patients with brucellar epididymo-orchitis are typically diagnosed on the basis of positive blood cultures or serology, or both. It is uncommon for urine analysis to show abnormalities. On occasions, Brucella species can be cultured from urine but the yield is low and this is not usually attempted. However, routine urine cultures should be taken in all patients to rule out other aetiologies.

A typical laboratory exposure to urine would not normally be regarded as constituting a significant hazardous exposure. However, a high risk exposure (for example, a conjunctival splash) of urine from an untreated patient with urinary tract involvement might be an exception to this rule. In such cases, ring BRU for advice on risk assessment.

EU Reference Laboratories (EURLs) aim to ensure high-quality, uniform testing in the EU and support Commission activities on risk management and risk assessment in the area of laboratory analysis. Regulation (EC) No 882/2004 on official controls defines tasks, duties and requirements for all the EURLs, a list of which is provided in its Annex VII. The Commission can establish new EURLs or change designation of existing ones. The European Parliament and the Council adopted the new Official Controls Regulation No 2017/625 on 15 March 2017. The new rules will gradually become applicable with the main application date being 14 December 2019.

Art. 94.2.c Coordinating the application by the national reference laboratories and, if necessary, by other official laboratories of the methods referred to in point (a), in particular, by organising regular inter-laboratory comparative testing or proficiency tests (PTs) and by ensuring appropriate follow-up, and informing the Commission and the Member States of the results and follow-up. In order to register to future ILPTs, please consult LEILA, our online platform:

Art. 94.2.l Where relevant for their area of competence, cooperate among themselves and with the Commission, as appropriate, to develop methods of analysis, testing or diagnosis of high standards.

Art.94.2.d Coordinating practical arrangements necessary to apply new methods of laboratory analysis, testing or diagnosis, and informing national reference laboratories of advances in this field.

Art. 94.2.e Conducting training courses for staff from national reference laboratories and, if needed, from other official laboratories, as well as of experts from third countries.

Art. 94.2.h Collaborating within the scope of their mission with laboratories in third countries and with the European Food Safety Authority (EFSA), the European Medicines Agency (EMA) and the European Centre for Disease Prevention and Control (ECDC).

Art. 94.2.i Assisting actively in the diagnosis of outbreaks in Member States of foodborne, zoonotic or animal diseases, or of pests of plants, by carrying out confirmatory diagnosis, characterisation and taxonomic or epizootic studies on pathogen isolates or pest specimens.

Art. 94.2.j Coordinating or performing tests for the verification of the quality of reagents and lots of reagents used for the diagnosis of foodborne, zoonotic or animal diseases and pests of plants.

Art. 94.2.k Where relevant for their area of competence, establishing and maintaining:

i. reference collections of pests of plants and/or reference strains of pathogenic agents;

ii. reference collections of materials intended to come into contact with food used to calibrate analytical equipment and provide samples thereof to national reference laboratories;

iii. up-to-date lists of available reference substances and reagents and of manufacturers and suppliers of such substances and reagents.

The Reference Laboratories are designated to pursue all the scientific and technical problems relating to a named disease. The Expert, responsible to WOAH and its Member Countries with regard to the disease, should be a leading and active researcher helping the Reference Laboratory to provide scientific and technical assistance and expert advice on topics linked to diagnosis and control of the disease for which the Reference Laboratory is responsible. Reference Laboratories should also provide scientific and technical training for personnel from Member Countries, and coordinate scientific and technical studies in collaboration with other laboratories or organisations, including through the Laboratory Twinning programme.

In May 2011, the World Assembly of Delegates of the WOAH (hereafter the Assembly) adopted new Terms of Reference (ToRs) and Internal Rules for WOAH Reference Centres. The ToRs for Reference Laboratories had emphasised their role in developing and recommending test methods, storing and distributing reference reagents, providing advice, diagnostic support and training to WOAH Members, and their reporting obligations. From 2011, the ToRs added the recommendation that laboratories establish and maintain a network with other WOAH Reference Laboratories designated for the same pathogen or disease and organise regular inter-laboratory proficiency testing to ensure comparability of results, as well as organise inter-laboratory proficiency testing with laboratories other than WOAH Reference Laboratories for the same pathogens and diseases to ensure equivalence of results.

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