title: Detection of macrolide resistance genes in culture-negative specimens from Bangladeshi children with invasive pneumococcal diseases.
abstract: In recent years, an increasing prevalence of macrolide resistance among pneumococci in Bangladesh has been observed. However, the scenario remains incomplete, as few isolates (<1%) are available from pneumonia cases and most pneumococcal meningitis cases (>80%) are culture-negative. This study optimised a triplex PCR method to detect macrolide resistance genes (MRGs) (mefA and ermB) and cpsA from culture-negative pneumococcal cases to predict the prevalence and level of macrolide resistance.
  
  
  
  The presence of MRGs among pneumococcal strains (n=153) with a wide range of erythromycin MICs (<0.5 to ≥256mg/L) was determined by PCR. Triplex PCR was validated by simultaneous detection of MRG(s) and cpsA in culture-negative clinical specimens and corresponding isolates. The known impact of the presence of specific MRG(s) on MICs of strains was used to predict the MICs of non-culturable strains based on the presence/absence of MRG(s) in the specimens.
  
  
  
  None of the erythromycin-susceptible isolates possessed any of the MRGs, and all non-susceptible strains had ≥1 MRG. MICs were 2-16mg/L and ≥256mg/L for 93% of strains with mefA and ermB, respectively, whereas 100% of isolates with both genes had MICs≥256mg/L. PCR for body fluids showed 100% concordance with corresponding isolates when tested for MRG(s) in parallel.
  
  
  
  Erythromycin MICs can be predicted for non-culturable strains with 93-100% precision based on detection of ermB and/or mefA. This method will be useful for establishing comprehensive surveillance for macrolide resistance among pneumococci, specifically in the population with prior antibiotic use.
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Dhaka 1207, Bangladesh.
authors.forename: Md
authors.initials: M
authors.lastname: Hasanuzzaman
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Dhaka 1207, Bangladesh.
authors.forename: Roly
authors.initials: R
authors.lastname: Malaker
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Dhaka 1207, Bangladesh.
authors.forename: Maksuda
authors.initials: M
authors.lastname: Islam
authors.affiliation: International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Abdullah H
authors.initials: AH
authors.lastname: Baqui
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Darmstadt
authors.affiliation: Respiratory Diseases Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Cynthia G
authors.initials: CG
authors.lastname: Whitney
authors.affiliation: Child Health Research Foundation, Department of Microbiology, Dhaka Shishu Hospital, Dhaka 1207, Bangladesh; Bangladesh Institute of Child Health, Dhaka Shishu Hospital, Dhaka, Bangladesh. Electronic address: samirk.sks@gmail.com.
authors.forename: Samir K
authors.initials: SK
authors.lastname: Saha
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000382:microbiology*; D001459:Bangladesh; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018942:Macrolides / Q000494:pharmacology; D008297:Male; D016920:Meningitis, Bacterial / Q000382:microbiology*; D008826:Microbial Sensitivity Tests / Q000379:methods*; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D011008:Pneumococcal Infections / Q000382:microbiology*; D012189:Retrospective Studies; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides
keywords: Bangladesh; Culture-negative; Invasive pneumococcal disease; Macrolide resistance gene