Invasive Haemophilus influenzae disease in the vaccine era in Rio de Janeiro, Brazil

BACKGROUND Haemophilus influenzae (Hi) serotype b (Hib) conjugate vaccine was incorporated into the infant immunisation schedule in Brazil in 1999, where Hib was one of the major etiologic sources of community-acquired bacterial meningitis. OBJECTIVES The purpose of this study is to describe the molecular epidemiology of invasive Hi disease in Rio de Janeiro state, Brazil, before and after vaccine introduction. METHODS Surveillance data from 1986 to 2014 were analysed. Hi isolates recovered from cerebrospinal fluid (CSF) or blood from 1993 to 2014 were serotyped by slide agglutination, genotyped by multilocus sequence typing (MLST), and the capsule type evaluation, differentiation of serologically non-typeable isolates, and characterisation of the capsule (cap) locus was done by polymerase chain reaction. Antimicrobial susceptibility testing was performed using E-test. FINDINGS From 1986 to 1999 and from 2000 to 2014, 2580 and 197 (42% without serotype information) confirmed cases were reported, respectively. The case fatality rate was 17% and did not correlate with the strain. Hib and b- variant isolates belonged to ST-6, whereas serotype a isolates belonged to the ST-23 clonal complex. Serotype a appeared to emerge during the 2000s. Non-encapsulated isolates were non-clonal and distinct from the encapsulated isolates. Ampicillin-resistant isolates were either of serotype b or were non-encapsulated, and all of them were β-lactamase-positive but amoxicillin-clavulanic acid susceptible. MAIN CONCLUSIONS Although Hi meningitis became a relatively rare disease in Rio de Janeiro after the introduction of the Hib conjugate vaccine, the isolates recovered from patients have become more diverse. These results indicate the need to implement an enhanced surveillance system to continue monitoring the impact of the Hib conjugate vaccine.

The utility of the polymerase chain reaction assay for aetiologic definition of unspecified bacterial meningitis cases

Most patients with acute suppurative meningitis are otherwise healthy individuals with regard to immune mechanisms against invasive bacterial disease. This medical emergency is among the most dramatic and potentially ravaging diseases that affect humans, particularly young children. The illness often strikes suddenly, and can either result in death or leave the survivors with significant neurological dysfunctions. The demonstration of a bacterial aetiology is necessary for decisions regarding treatment and prophylaxis. Conventional bacteriological methods frequently fail to identify an agent, as a result of administration of antibiotics or delayed lumbar punctures. We investigated the major aetiologic sources of unspecified bacterial meningitis cases (G00.9, ISCD-10) by polymerase chain reaction (PCR)-based identification of Neisseria meningitidis (crgA), Streptococcus pneumoniae (ply) and Haemophilus influenzae (bexA) in cerebrospinal fluid samples. The multiplex PCR detected N. meningitidis in 92 percent, S. pneumoniae in 4 percent and H. influenzae in 1 percent of the 192 clinical samples assayed; 3 percent were negative for all three DNA targets. Bacterial DNA detection was found to be a valuable adjunct to enhance bacterial meningitis surveillance when the yield of specimens by culture is reduced. The implementation of PCR assays as a diagnostic procedure in Public Health Laboratories is perceived to be a significant advance in the investigation of bacterial meningitis.

Recognition of the epidemiological significance of Neisseria meningitidis capsular serogroup W135 in the Rio de Janeiro region, Brazil

Neisseria meningitidis retains its ability to cause endemic and hiperendemic disease in human population living in any environment, as well as localized outbreaks and massive epidemics in civilians and military personnel. In Rio de Janeiro it has been reported in the 1990s as prolonged outbreak of serogroup B and at least one epidemic of serogroup C was well defined, both demanding quick action by the Public Health authorities. We report here the emergence of serogroup W135 meningococcal disease causing endemic and case cluster in Rio de Janeiro during the first years of this new century.

Assessment of a two-step nucleic acid amplification assay for detection of Neisseria meningitidis followed by capsular genogrouping

Immediate prevention of meningococcal disease relies in part on the prompt treatment with antibiotics of household and other close contacts of cases; however intervention with effective vaccination relies on identification of serogroup-causing strains. Parenteral antibiotic for patient with suspected meningococcal disease before hospital admission is currently recommended. Laboratory standard methods are hindered by failure to detect bacteria by this medical approach to improve patient prognosis. We assessed two polymerase chain reaction (PCR) assays to detect (crgA) and define the serogroups (siaD, orf-2, and ctrA) of Neisseria meningitidis in 120 cerebrospinal fluid (CSF) samples from positive cases (culture or antigen detection or direct smear). The PCR sensitivity for the identification of N. meningitidis was 100 percent (95 percent confidence interval, CI, 96-100 percent) compared to a sensitivity of 46 percent for culture (95 percent CI 37-55 percent), 61 percent for latex agglutination test (95 percent CI 52-70 percent), and 68 percent for Gram stain (95 percent CI 59-76 percent); PCR specificity was 97 percent (95 percent CI 82-100 percent). PCR correctly identified the serogroups A, B, C, W135, Y, and X in CSF samples with a sensitivity of 88 percent (95 percent CI 80-93 percent); the primer sets were 100 percent specific. The introduction of PCR-based assays shall increase laboratory confirmed cases, consequently enhancing surveillance of meningococcal disease.

Diagnosis of Streptococcus pneumoniae meningitis by polymerase chain reaction amplification of the gene for pneumolysin

Diagnosis of bacterial meningitis has long been based on classical methods of Gram stain, serological tests, and culture of cerebrospinal fluid (CSF). The performance of these methods, especially culture and direct smear, is thwarted by failure to detect bacteria following administration of antimicrobial agents and reluctance to performance lumbar punctures at admission. Indeed, patients with meningitis frequently receive antibiotics orally or by injection before the diagnosis is suspected or established. Thus an alternative method has become necessary to help clinicians and epidemiologists to management and control of bacterial meningitis. We evaluate the application of a polymerase chain reaction-based (PCR) assay for amplification of pneumolysin gene (ply) to diagnosis of Streptococcus pneumoniae meningitis. The PCR assay sensitivity for CSF was 96 percent (95 percent confidence interval, CI, 90-99 percent) compared to a sensitivity of 59 percent for culture (95 percent CI 49-69 percent), 66 percent for Gram stain (95 percent CI 56-74 percent), and 78 percent for latex agglutination test (95 percent CI 69-86 percent); PCR specificity was 100 percent (95 percent CI 83-100 percent). PCR results were available within 4 h of the start of the assay. This molecular approach proved to be reliable and useful to identify this bacterium compared with other classical laboratory methods for identification of bacterial meningitis pathogens.