Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-5 (of 5 Records) |
Query Trace: Carvalho Mda G[original query] |
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Non-pneumococcal mitis-group streptococci confound detection of pneumococcal capsular serotype-specific loci in upper respiratory tract
Carvalho Mda G , Pimenta FC , Moura I , Roundtree A , Gertz RE Jr , Li Z , Jagero G , Bigogo G , Junghae M , Conklin L , Feikin DR , Breiman RF , Whitney CG , Beall BW . PeerJ 2013 1 e97 We performed culture-based and PCR-based tests for pneumococcal identification and serotyping from carriage specimens collected in rural and urban Kenya. Nasopharyngeal specimens from 237 healthy children <5 years old (C-NPs) and combined nasopharyngeal/oropharyngeal specimens from 158 adults (A-NP/OPs, 118 HIV-positive) were assessed using pneumococcal isolation (following broth culture enrichment) with Quellung-based serotyping, real-time lytA-PCR, and conventional multiplexed PCR-serotyping (cmPCR). Culture-based testing from C-NPs, HIV-positive A-NP/OPs, and HIV-negative A-NP/OPs revealed 85.2%, 40.7%, and 12.5% pneumococcal carriage, respectively. In contrast, cmPCR serotypes were found in 93.2%, 98.3%, and 95.0% of these sets, respectively. Two of 16 lytA-negative C-NPs and 26 of 28 lytA-negative A-NP/OPs were cmPCR-positive for 1-10 serotypes (sts) or serogroups (sgs). A-NP/OPs averaged 5.5 cmPCR serotypes/serogroups (5.2 in HIV-positive, 7.1 in HIV-negative) and C-NPs averaged 1.5 cmPCR serotypes/serogroups. cmPCR serotypes/serogroups from lytA-negative A-NP/OPs included st2, st4, sg7F/7A, sg9N/9L, st10A, sg10F/10C/33C, st13, st17F, sg18C/18A/18B/18F, sg22F/22A, and st39. Nine strains of three non-pneumococcal species (S. oralis, S. mitis, and S. parasanguinis) (7 from A-OP, 1 from both A-NP and A-OP, and 1 from C-NP) were each cmPCR-positive for one of 7 serotypes/serogroups (st5, st13, sg15A/15F, sg10F/10C/33C, sg33F/33A/37, sg18C/18A/18B/18F, sg12F/12A/12B/ 44/46) with amplicons revealing 83.6-99.7% sequence identity to pneumococcal references. In total, 150 cmPCR amplicons from carriage specimens were sequenced, including 25 from lytA-negative specimens. Amplicon sequences derived from specimens yielding a pneumococcal isolate with the corresponding serotype were identical or highly conserved (>98.7%) with the reference cmPCR amplicon for the st, while cmPCR amplicons from lytA-negative specimens were generally more divergent. Separate testing of 56 A-OPs and 56 A-NPs revealed that approximately 94% of the positive cmPCR results from A-NP/OPs were from OP microbiota. In contrast, A-NPs yielded >2-fold more pneumococcal isolates than A-OPs. Verified and suspected non-pneumococcal cmPCR serotypes/serogroups appeared to be relatively rare in C-NPs and A-NPs compared to A-OPs. Our findings indicate that non-pneumococcal species can confound serotype-specific PCR and other sequence-based assays due to evolutionarily conserved genes most likely involved in biosynthesis of surface polysaccharide structures. |
Molecular epidemiological investigation to determine the source of a fatal case of serotype 22F pneumococcal meningitis.
Lamaro-Cardoso J , de Lemos AP , Carvalho Mda G , Pimenta FC , Roundtree A , Motta L , Vieira MA , Sgambatti S , Thorn LK , Pessoa-Junior V , Minamisava R , Harrison LH , Beall BW , Brandileone MC , Andrade AL . J Med Microbiol 2012 61 686-92 A child's death due to pneumococcal meningitis after contracting the disease in an after-school programme prompted an investigation to assess nasopharyngeal (NP) carriage among her contacts. The serotype of the meningitis case isolate was determined, together with the serotypes of the NP specimens of contacts, comprising the case patient's brother, the case patient's after-school programme contacts and the brother's day-care centre (DCC) contacts. NP swabs from 155 children and 69 adults were obtained. Real-time PCR and conventional multiplex PCR (CM-PCR) assays were used to detect pneumococcal carriage and determine serotypes. Broth-enriched culture of NP specimens followed by pneumococcal isolation and Quellung-based serotyping were also performed. DNA extracts prepared from cerebrospinal fluid of the index case and from the NP strain isolated from the brother and from one attendee of the brother's DCC were subjected to genotyping. Pneumococcal carriage assessed by real-time PCR and culture was 49.6 and 36.6 %, respectively (P<0.05). Twenty-three serotypes were detected using CM-PCR, with serotypes 6A/6B, 14, 19F, 6C/6D, 22F/22A, 23F and 11A/11D being the most frequent. All eight serotype 22F/22A NP specimens recovered were from children attending the brother's DCC. The meningitis case isolate and the NP carriage isolate from the patient's brother were both serotype 22F and shared the same new multilocus sequence type (ST6403) with the attendee of the brother's DCC. CM-PCR proved to be useful for assessing carriage serotype distribution in a setting of high-risk pneumococcal transmission. The causal serotype appeared to be linked to the brother of the case patient and attendees of his DCC. |
Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae prior to introduction of the 10-valent pneumococcal conjugate vaccine in Brazil, 2000-2007
Menezes AP , Campos LC , Dos Santos MS , Azevedo J , Dos Santos RC , Carvalho Mda G , Beall BW , Martin SW , Salgado K , Reis MG , Ko AI , Reis JN . Vaccine 2011 29 (6) 1139-44 This study describes the serotype distribution and antibiotic resistance patterns among 397 S. pneumoniae meningitis case isolates recovered in Salvador, Brazil, during the period of 2000-2007, before introduction of the 10-valent pneumococcal conjugate vaccine. The active hospital-based surveillance showed a decline in the annual incidence rates of pneumococcal meningitis during the period of study, from 1.12 cases to 0.83 cases/100,000 persons for all age groups (P<0.001), with an overall case-fatality rate of 28.6% (113 of 395) for all patients and 41.9% (57 of 136) for those <5 years of age. Serotypes 14 (n=55; 13.9%), 3 (n=32; 8.1%), 23F (n=32; 8.1%), 19F (n=31; 7.8%), 6B (n=30; 7.6%), 18C (n=28; 7.1%), and 6A (n=20; 5%) were the most prevalent serotypes. In patients <5 years the estimated projected coverage of 7-, 10- and 13-valent conjugate vaccines was 74.3%, 75.7% and 83.1%, respectively. Antimicrobial susceptibility testing revealed that 22.1% (n=88) of isolates were non-susceptible to penicillin, 56% were non-susceptible to trimethoprim/sulphamethoxazole, and 29.6% were non-susceptible to tetracycline. Nonsusceptibility to penicillin and cefotaxime was detected solely among serotype 14 isolates (n=4; 1%). This study provides an important baseline to assess the impact of conjugate vaccine implantation on the epidemiology of meningitis due to Streptococcus pneumoniae in Salvador, Brazil. |
Prevalence of Streptococcus pneumoniae serotype 6C among invasive and carriage isolates in metropolitan Salvador, Brazil, from 1996 to 2007
Campos LC , Carvalho Mda G , Beall BW , Cordeiro SM , Takahashi D , Reis MG , Ko AI , Reis JN . Diagn Microbiol Infect Dis 2009 65 (2) 112-5 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. |
Rarely occurring 19A-like cps locus from a serotype 19F pneumococcal isolate indicates continued need of serology-based quality control for PCR-based serotype determinations
Pimenta FC , Gertz RE Jr , Roundtree A , Yu J , Nahm MH , McDonald RR , Carvalho Mda G , Beall BW . J Clin Microbiol 2009 47 (7) 2353-4 Determination of the DNA sequences corresponding to all 91 pneumococcal capsular biosynthetic (cps) loci (1, 3, 6, 9) has allowed serotype determinations from pneumococcal isolates and clinical specimens using conventional PCR assays (2, 4, 7, 8, 10). We developed sequential, multiplexed PCR schemes that resolve 33 serologic specificities, including 20 serotypes and 13 serotype subsets (4, 7, 8). We recently expanded the scheme to 40 specificities (www.cdc.gov/ncidod/biotech/strep/pcr.htm). | PCR primers targeted serotype-specific open reading frames within central portions of known cps loci (4, 7, 8). Subsequent information (1, 3, 6) revealed that we primarily targeted serotype-specific oligosaccharide repeat unit polymerases (wzy encoded), glycosyl transferases, and flippases (wzx encoded). Our serotype 19A primers, however, targeted the mnaA gene that encodes UDP-N-acetylglucosamine-2-epimerase (8). Although the mnaA sequence differs markedly among the 15 cps loci that harbor it (serotypes 19A, -B, -C, -F; 12A, -B, -F; 9A, -N, -L, -V; 4; 36; 44; 46), due to potential exchanges of heterologous mnaA genes, we recently changed the 19A PCR assay to target wzy (our unpublished data). The wzy19A and wzy19F genes putatively provide the basis of the structural difference between the related 19A and 19F capsules (1). |
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