Laboratory confirmation of meningococcal disease in Scotland, 1993-9

Epidemiology of two decades of invasive meningococcal disease in the Republic of Ireland: an analysis of national surveillance data on laboratory-confirmed cases from 1996 to 2016

We examined the epidemiology of invasive meningococcal disease (IMD) in the Republic of Ireland (ROI) between epidemiological year (EY) 1996/1997 and EY2015/2016. Over the 20 EYs, 3707 cases were reported with annual incidence rates per 100 000 peaking at 11.6 in EY1999/2000, decreasing significantly to 1.5 in EY2015/2016. The highest disease burden was in infants and children <5, whereas adults aged ⩾65 years experienced the highest case fatality ratio (CFR) of 15.7% but over the study period the median annual CFR remained low (4.4%). Meningococcal serogroup B (menB) dominated (78%), followed by menC (17%), menW (1%) and menY (1%). The incidence of menC IMD declined significantly in all age groups after menC vaccine introduction in 2000. MenB incidence also declined over the 20 EYs with decreasing trends in all age groups under 65, including an almost 50% decrease in infants over the final four EYs. IMD incidence in the ROI has declined, partly attributable to menC vaccination success, coupled with a spontaneous decline in menB. However, recent gradual increases in non-menB IMD and the introduction of vaccines targeting menB demand continued detailed surveillance to accurately monitor trends and to assess vaccine impact.

Molecular methods for the detection and characterization ofNeisseria meningitidis

Neisseria meningitidis remains a common global cause of morbidity and mortality. The laboratory confirmation of meningococcal disease is, therefore, very important for individual patient management and for public health management. Through surveillance schemes, it provides long-term epidemiologic data that can be used to inform vaccine policy. Traditional methods, such as latex agglutination and the enzyme-linked immunosorbent assay, are still used, but molecular methods are now also established. In this review, molecular methods for the laboratory confirmation and characterization of meningococci are described. PCR is an invaluable tool in modern biology and can be used to predict the group, type and subtype of meningococci. It is now also used in a fluorescence-based format for increased sensitivity and specificity. The method also provides the amplified DNA for other techniques, such as multilocus sequence typing. Other methods for the discrimination of meningococci have also played and continue to play an important part in epidemiology. For example, pulsed-field gel electrophoresis is highly discriminatory, whilst multilocus enzyme electrophoresis provided the basis for the description of global meningococcal clones and formed the foundation for multilocus sequence typing. Other less commonly used methods, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and pyrosequencing, may increasingly find their way into microbiology reference laboratories. Nevertheless, nucleotide sequencing and laboratory automation have aided the introduction of many methods and provide data that are digitally based and, therefore, highly accurate and portable.

Specific PCR Assay for Rapid and Direct Detection of Neisseria meningitidis in Cerebrospinal Fluid Specimens

BACKGROUND

Neisseria meninigitidis is one of the most frequently encountered microorganisms associated with central nervous system infections. The aim of this study was to evaluate a PCR-based assay for specific and rapid detection of N. meninigitidis in CSF specimens.

METHODS

Since April 2002 to July 2006, 130 CSF specimens were collected from patients suspected of having bacterial meningitis. Bacterial isolation and identification was carried out according to the standard bacteriological methods. The PCR was used to amplify a 101bp fragment of capsular transport gene A (ctrA) of N. meningitidis.

RESULTS

PCR yielded an amplified product with the expected size of 101 base pair fragment. Sensitivity test proved 500 ng of N. meningitidis DNA as the final detection limit and specificity test revealed no cross-reaction for a wide range of respiratory pathogenic organisms.

CONCLUSION

The PCR assay was more sensitive than the bacterial culturing. It might be possible to apply this procedure for rapid diagnosis of meningococci in clinical samples.

Assessing the relationship between HIV infection and cervical cancer in Côte d'Ivoire: a case-control study

Background

The association between HIV infection and invasive cervical cancer that has been reported may reflect differential prevalence of human papillomavirus (HPV) infection or uncontrolled confounding. We conducted a case-control study in a West African population to assess the relationship between HIV infection and invasive cervical cancer, taking into account HPV infection and other potential risk factors for cervical cancer.

Methods

Women with invasive cervical cancer (cases) or normal cervical cytology (controls) were recruited in a hospital-based case-control study in Abidjan, Côte d'Ivoire. Odds ratios and 95% confidence intervals (CI) were estimated in logistic regression analyses controlling for important cofactors.

Results

HIV infection was noted in 22/132 (16.7%) cases and 10/120 (8.3%) controls (p = 0.048). High-risk HPV infection was detected in cervical tumor samples from 89.4% of case-participants and in cervical cytology samples in 31.1% of control-participants. In logistic regression analysis, HIV infection was associated with cervical cancer in women with HPV (OR 3.4; 95% CI 1.1-10.8). Among women aged ≤ 40 years, risk factors for cervical cancer were high-risk HPV infection (OR 49.3; 95% CI 8.2-295.7); parity > 2 (OR 7.0; 95% CI 1.9-25.7) and HIV infection (OR 4.5; 95% CI 1.5-13.6). Among women aged > 40 years, high-risk HPV infection (OR 23.5; 95% CI 9.1-60.6) and parity > 2 (OR 5.5; 95% CI 2.3-13.4), but association with HIV infection was not statistically significant.

Conclusions

These data support the hypothesis that HIV infection is a cofactor for cervical cancer in women with HPV infection, and, as in all populations, the need for promoting cervical screening in populations with high prevalence of HIV infection.

Increased genetic diversity of Neisseria meningitidis isolates after the introduction of meningococcal serogroup C polysaccharide conjugate vaccines

During the 1990s, the incidence of meningococcal disease was high in the United Kingdom. This was due primarily to an increase in serogroup C disease, particularly that within the ET-37/ST-11 genetic lineage. Serogroup C meningococcal polysaccharide conjugate vaccines were introduced in the United Kingdom in 1999, but the sequence types of meningococci causing disease since that time have not yet been reported. We have used serogrouping and multilocus sequence typing to characterize meningococci from patients with invasive disease over a 4-year period and show that there is a significant increase in genetic diversity but no genetic evidence of capsule switching.

[Meningococcal disease diagnostic criteria in Greater Metropolitan Campinas, São Paulo State, Brazil]

The aim of this article is to evaluate confirmatory criteria: culture, latex agglutination, counter immunoelectrophoresis, microscopic examination, and clinical/epidemiological criteria for cases of meningococcal disease reported in Greater Metropolitan Campinas, São Paulo State, Brazil, from 1993 to 2002 (568 cases). The following variables were also studied: clinical features, gender, age, city, hospital, case fatality, seasonality, and Neisseria meningitidis serogroup. Culture as a confirmatory criterion was the dependent variable in univariate analysis. The mean proportion of confirmatory criterion by culture was 68.7%. Clinical features of meningococcal disease -- meningitis without septicemia (OR = 2.87; CI: 1.89-4.38) and septicemia without meningitis (OR = 0.26; CI: 0.17-0.45) -- were associated with confirmation by culture. Case fatality rates were different among all diagnostic criteria. More attention should be given to etiological diagnostic confirmation in more severe cases. Diagnostic methods such as PCR may improve etiological confirmation of meningococcal disease in cases with negative cultures.

Real-time Fluorescent PCR Techniques to Study Microbial-Host Interactions

This chapter describes how real-time polymerase chain reaction (PCR) performs and how it may be used to detect microbial pathogens and the relationship they form with their host. Research and diagnostic microbiology laboratories contain a mix of traditional and leading-edge, in-house and commercial assays for the detection of microbes and the effects they impart upon target tissues, organs, and systems. The PCR has undergone significant change over the last decade, to the extent that only a small proportion of scientists have been able or willing to keep abreast of the latest offerings. The chapter reviews these changes. It discusses the second-generation of PCR technology-kinetic or real-time PCR, a tool gaining widespread acceptance in many scientific disciplines but especially in the microbiology laboratory.

Real-time PCR in the microbiology laboratory

Use of PCR in the field of molecular diagnostics has increased to the point where it is now accepted as the standard method for detecting nucleic acids from a number of sample and microbial types. However, conventional PCR was already an essential tool in the research laboratory. Real-time PCR has catalysed wider acceptance of PCR because it is more rapid, sensitive and reproducible, while the risk of carryover contamination is minimised. There is an increasing number of chemistries which are used to detect PCR products as they accumulate within a closed reaction vessel during real-time PCR. These include the non-specific DNA-binding fluorophores and the specific, fluorophore-labelled oligonucleotide probes, some of which will be discussed in detail. It is not only the technology that has changed with the introduction of real-time PCR. Accompanying changes have occurred in the traditional terminology of PCR, and these changes will be highlighted as they occur. Factors that have restricted the development of multiplex real-time PCR, as well as the role of real-time PCR in the quantitation and genotyping of the microbial causes of infectious disease, will also be discussed. Because the amplification hardware and the fluorogenic detection chemistries have evolved rapidly, this review aims to update the scientist on the current state of the art. Additionally, the advantages, limitations and general background of real-time PCR technology will be reviewed in the context of the microbiology laboratory.

Automation of a fluorescence-based multiplex PCR for the laboratory confirmation of common bacterial pathogens

A fluorescence-based multiplex PCR was automated for the simultaneous detection of Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae in clinical samples from patients with suspected meningitis. Sensitivity of one to two genome copies per 100 μl sample and specificity of 100 % for each organism were shown. Automation of DNA extraction, liquid handling, PCR and analysis are achieved on a single platform, which enables a high throughput and rapid turnaround of clinical samples that, in turn, leads to faster diagnosis. This is ultimately beneficial to the treatment of the patient and for public health management.

Nucleotide sequence-based typing of meningococci directly from clinical samples

The unpredictable characteristics of meningococcal disease (MD) make outbreaks complicated to monitor and consequently lead to high levels of public anxiety. Traditional molecular techniques have been utilized in order to understand better the epidemiology of MD, but some have disadvantages such as being highly specialized and labour-intensive, with low reproducibility. Some of these problems have been overcome by using multilocus sequence typing (MLST). This technique exploits the unambiguous nature and electronic portability of nucleotide sequencing data for the characterization of micro-organisms. The need for enhanced surveillance of MD after the introduction of serogroup C conjugate vaccines means that it is important to gain typing information from the infecting organism in the absence of a culture isolate. Here, the application of MLST for the laboratory confirmation and characterization of Neisseria meningitidis directly from clinical samples is described. This involved using a newly designed set of primers that were complementary to nucleotide sequences external to the existing MLST primers already in use for culture-based MLST of meningococci. This combination has produced a highly sensitive procedure to allow the efficient genotypic characterization of meningococci directly from clinical samples.

Identification of Neisseria meningitidis serogroups Y and W135 by siaD nucleotide sequence analysis

Rapid serogrouping of meningococci is essential for the effective public health management of cases of the disease and the contacts of infected patients. Here we describe an accurate nucleotide-sequencing method for the confirmation of serogroup Y and W135 meningococci by siaD gene analysis from cultures of Neisseria meningitidis.

Detection and genotyping of meningococci using a nested PCR approach

An effective vaccine against Neisseria meningitidis serogroup B is required. Outer-membrane protein vaccines have been developed, which may provide protection against common circulating serotypes and serosubtypes in some countries. However, limited genosubtyping data are available because most laboratories use mAbs directed against a limited number of specific serotypes and serosubtypes and laboratories do not genosubtype directly from body fluids due to the lack of a sensitive PCR method. A nested PCR was therefore developed that enables the amplification of the porA gene directly from clinical samples and has the required sensitivity for nucleotide sequencing of the three main variable regions, VR1, VR2 and VR3. Data were compared with those from culture-based nucleotide sequencing, and the use of this method increased the availability of genosubtype information by 45 %, thereby indicating the impact that this methodology has on the data provided and the implications for vaccine design.