Soraia Machado Cordeiro

Prevention of Haemophilus influenzae Type b (Hib) Meningitis and Emergence of Serotype Replacement with Type a Strains after Introduction of Hib Immunization in Brazil

Surveillance for Haemophilus influenzae meningitis cases was performed in Salvador, Brazil, before and after introduction of H. influenzae type b (Hib) immunization. The incidence of Hib meningitis decreased 69% during the 1-year period after initiation of Hib immunization (from 2.62 to 0.81 cases/100,000 person-years; P<.001). In contrast, the incidence for H. influenzae type a meningitis increased 8-fold (from 0.02 to 0.16 cases/100,000 person-years; P=.008). Pulsed-field gel electrophoretic analysis demonstrated that H. influenzae type a isolates belonged to 2 clonally related groups, both of which were found before Hib immunization commenced. Therefore, Hib immunization contributed to an increased risk for H. influenzae type a meningitis through selection of circulating H. influenzae type a clones. The risk attributable to serotype replacement is small in comparison to the large reduction in Hib meningitis due to immunization. However, these findings highlight the need to maintain surveillance as the use of conjugate vaccines expands worldwide.

Accuracy of real-time PCR, Gram stain and culture for Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae meningitis diagnosis

BackgroundAlthough cerebrospinal fluid (CSF) culture is the diagnostic reference standard for bacterial meningitis, its sensitivity is limited, particularly when antibiotics were previously administered. CSF Gram staining and real-time PCR are theoretically less affected by antibiotics; however, it is difficult to evaluate these tests with an imperfect reference standard.Methods and findingsCSF from patients with suspected meningitis from Salvador, Brazil were tested with culture, Gram stain, and real-time PCR using S. pneumoniae, N. meningitidis, and H. influenzae specific primers and probes. An antibiotic detection disk bioassay was used to test for the presence of antibiotic activity in CSF. The diagnostic accuracy of tests were evaluated using multiple methods, including direct evaluation of Gram stain and real-time PCR against CSF culture, evaluation of real-time PCR against a composite reference standard, and latent class analysis modeling to evaluate all three tests simultaneously.ResultsAmong 451 CSF specimens, 80 (17.7%) had culture isolation of one of the three pathogens (40 S. pneumoniae, 36 N. meningitidis, and 4 H. influenzae), and 113 (25.1%) were real-time PCR positive (51 S. pneumoniae, 57 N. meningitidis, and 5 H. influenzae). Compared to culture, real-time PCR sensitivity and specificity were 95.0% and 90.0%, respectively. In a latent class analysis model, the sensitivity and specificity estimates were: culture, 81.3% and 99.7%; Gram stain, 98.2% and 98.7%; and real-time PCR, 95.7% and 94.3%, respectively. Gram stain and real-time PCR sensitivity did not change significantly when there was antibiotic activity in the CSF.ConclusionReal-time PCR and Gram stain were highly accurate in diagnosing meningitis caused by S. pneumoniae, N. meningitidis, and H. influenzae, though there were few cases of H. influenzae. Furthermore, real-time PCR and Gram staining were less affected by antibiotic presence and might be useful when antibiotics were previously administered. Gram staining, which is inexpensive and commonly available, should be encouraged in all clinical settings.

Clonally related penicillin-nonsusceptible Streptococcus pneumoniae serotype 14 from cases of meningitis in Salvador, Brazil.

Active hospital-based surveillance in the city of Salvador, Brazil, from December 1995 through October 1998, identified 221 patients with confirmed pneumococcal meningitis. Of these 221 patients, 29 (13%) had isolates with intermediate-level resistance to penicillin. Infection with these penicillin-nonsusceptible isolates was significantly associated with age of <2 years (P<.0019), previous antibiotic use (P<.0006), and coresistance to trimethoprim-sulfamethoxazole (P<.0000). Serotype 14 was the most prevalent serotype (55.2%) of penicillin-nonsusceptible isolates. Strain typing by repetitive element BOX polymerase chain reaction (PCR) analysis showed that penicillin-nonsusceptible serotype 14 isolates had closely related BOX PCR patterns, whereas penicillin-susceptible serotype 14 isolates each had distinct, unrelated patterns. Penicillin-nonsusceptible serotype 14 isolates from Salvador and other Brazilian cities had similar BOX PCR patterns. These observations indicate that in Brazil a large proportion of cases of penicillin-nonsusceptible pneumococcal meningitis appear to be caused by a closely related group of serotype 14 strains that may have disseminated to widely separate geographic areas.

Prevalence of Streptococcus pneumoniae serotype 6C among invasive and carriage isolates in metropolitan Salvador, Brazil, from 1996 to 2007.

The newly described Streptococcus pneumoniae serotype 6C accounted for 2.3% (16/709) of meningitis cases and 3.2% (3/95) of nasopharyngeal isolates from healthy individuals in Brazil. The strains were multidrug resistant (18.8%) and genetically diverse. Despite low serotype 6C prevalence, continuous surveillance is necessary to guide vaccine strategies.

Transmission of Streptococcus pneumoniae in an urban slum community

BACKGROUND Inhabitants of slum settlements represent a significant proportion of the population at risk for pneumococcal disease in developing countries. METHODS We conducted a household survey of pneumococcal carriage among residents of a slum community in the city of Salvador, Brazil. RESULTS Among 262 subjects, 95 (36%) were colonized with Streptococcus pneumoniae. Children <5 years of age (OR, 8.0; 95% CI, 3.5-18.6) and those who attended schools (OR, 2.7, 95% CI, 1.2-6.0) had significantly higher risk of being colonized. Of 94 isolates obtained from colonized individuals, 51% had serotypes included in the seven-valent pneumococcal conjugate vaccine. Overall, 10% (9 of 94 isolates) were nonsusceptible to penicillin and 28% (27 of 94 isolates) were resistant to cotrimoxazole. BOX-PCR, PFGE and MLST analyses found that 44% of the carriage isolates belonged to 14 distinct clonal groups. Strains of the same clonal group were isolated from multiple members of 9 out of the 39 study households. Nineteen carriage isolates had genotypes that were the same as those identified among 362 strains obtained from active surveillance for meningitis. CONCLUSIONS The studys findings indicate that there is significant intra- and inter-household spread of S. pneumoniae in the slum community setting. However, a limited number of clones encountered during carriage among slum residents were found to cause invasive disease.

Poor Clinical Outcome for Meningitis Caused by Haemophilus influenzae Serotype A Strains Containing the IS1016-bexA Deletion

Since the introduction of Haemophilus influenzae type b (Hib) conjugate vaccines, meningitis caused by serotypes other than Hib has gained in importance. We conducted active hospital-based surveillance for meningitis over an 11-year period in Salvador, Brazil. H. influenzae isolates were serotyped and analyzed by polymerase chain reaction, pulsed-field gel electrophoresis, and DNA sequencing to identify strains with a specific deletion (IS1016) in the bexA gene (IS1016-bexA). We identified 43 meningitis cases caused by non-type b H. influenzae: 28 (65%) were caused by type a (Hia), 9 (21%) were caused by noncapsulated strains, and 3 (7%) each were caused by types e and f. Hia isolates clustered in 2 clonal groups; clonal group A strains (n = 9) had the IS1016-bexA deletion. Among children <5 years of age, meningitis caused by Hia from clonal group A had higher case-fatality than meningitis caused by clonal group B. Despite small numbers, these results indicate that the presence of the IS1016-bexA deletion is associated with enhanced virulence in non-type b H. influenzae.

Population-based survey of antimicrobial susceptibility and serotype distribution of streptococcus pneumoniae from meningitis patients in Salvador, Brazil

ABSTRACT Penicillin-nonsusceptible strains were isolated from 15% of 303 individuals with pneumococcal meningitis identified during a 4-year surveillance study in Salvador, Brazil. The estimated rate of coverage of the seven-valent conjugate vaccine was 74% among patients <5 years of age and 94% among those infected with nonsusceptible isolates, indicating that the use of conjugate vaccines may be an approach to the control of emerging penicillin resistance in Brazil.

Clinical outcome of pneumococcal meningitis during the emergence of pencillin-resistant Streptococcus pneumoniae: an observational study

BackgroundPrior to the availability of generic third-generation cephalosporins, penicillins were widely used for treatment of pneumococcal meningitis in developing countries despite concerns about rising levels of penicillin resistance among pneumococcal isolates. We examined the impact of penicillin resistance on outcomes of pneumococcal meningitis over a ten year period in an infectious diseases hospital in Brazil.MethodsClinical presentation, antimicrobial therapy and outcomes were reviewed for 548 patients with culture-confirmed pneumococcal meningitis from December, 1995, to November, 2005. Pneumococcal isolates from meningitis patients were defined as penicillin-resistant if Minimum Inhibitory Concentrations for penicillin were greater than 0.06 μg/ml. Proportional hazards regression was used to identify risk factors for fatal outcomes.ResultsDuring the ten-year period, ceftriaxone replaced ampicillin as first-line therapy for suspected bacterial meningitis. In hospital case-fatality for pneumococcal meningitis was 37%. Of 548 pneumococcal isolates from meningitis cases, 92 (17%) were resistant to penicillin. After controlling for age and severity of disease at admission, penicillin resistance was associated with higher case-fatality (Hazard Ratio [HR], 1.62; 95% Confidence Interval [CI], 1.08-2.43). Penicillin-resistance remained associated with higher case-fatality when initial therapy included ceftriaxone (HR, 1.68; 95% CI 1.02-2.76).ConclusionsFindings support the use of third generation cephalosporin antibiotics for treatment of suspected pneumococcal meningitis even at low prevalence of pneumococcal resistance to penicillins.

Replacement of Neisseria meningitidis C cc11/ET-15 variant by a cc103 hypervirulent clone, Brazil 2005–2011

Outbreaks caused by serogroup C meningococci in the northeast region of Brazil from 2005 to 2011 were associated to the emergence of variant ET-15 of cc11, which has been replaced by cc103 from 2006 to date. The increase of cc103 should be closely monitored to prevent the spread of this clone to neighbouring regions.

Dissemination of the ST-103 clonal complex serogroup C meningococci in Salvador, Brazil

Invasive meningococcal disease (IMD) is a major public health problem worldwide. An epidemic of serogroup C (NmC) IMD occurred in 2010 in the city of Salvador. In this study, we describe the antigenic and genetic characterization of meningococcal isolates collected from meningitis cases in Salvador from 2001 to 2012. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed for the analysis of IMD isolates. A total of 733 cases were identified, and the serogroup was determined for 391 (53.0%) of these. Most cases were caused by NmC (53%) or B (47%). The most prevalent strains were B:4,7:P1.19,15 (32.9%; 129/391) and C:23:P1.14-6 (28.6%; 112/391). Based on PFGE/MLST analysis, 71.3% (77/108 PFGE-tested isolates) clustered as two clones of sequence type ST-3779 and ST-3780, both belonging to the ST-103 clonal complex. ST-3779 has been detected in Salvador since 1996 and together with ST-3780 became predominant after 2005. There was a predominance of C:23:P1.14-6, ST-3779/3780 in Salvador during the period of 2007-2012, establishing a major clonal lineage, which remained in the community for a long time; this has serious implications for public health, particularly in terms of prevention and control strategies of IMD.