PURPOSE: Outbreaks of bacterial conjunctivitis have been linked to nontypeable strains of Streptococcus pneumoniae that lack a capsule, a key virulence factor for invasive infections. In contrast, isolates from sporadic, nonoutbreak cases of conjunctivitis were thought to be similar to invasive or nasopharyngeal isolates with respect to their capsular serotype and antibiotic resistance profile. This hypothesis was tested for 302 strains isolated during three prospective, multicenter clinical studies of bacterial conjunctivitis. MATERIALS AND METHODS: S. pneumoniae capsular serotypes were determined by agglutination assay and confirmed by the Statens Serum Institute. The presence of the cpsAB capsule genes was determined by polymerase chain reaction (PCR). Minimum inhibitory concentrations were measured for 17 antibacterial drugs by the broth microdilution method. RESULTS: Only 25 (8.3%) isolates reacted with the capsule-specific antisera and only one (0.3%) of these serotypes was covered by the capsule-specific PCV7 vaccine. The remaining 277 (91.7%) isolates were nontypeable, suggesting that they did not produce a capsule. PCR analysis indicated the loss of the capsule operon in 24/25 randomly selected nontypeable strains. Resistance rates were highest for azithromycin, trimethoprim, and tetracycline, while no resistance was detected for the fluoroquinolones, linezolid, and vancomycin. Antibiotic resistance rates were generally lower than those reported for invasive isolates, although some highly resistant or multidrug-resistant isolates were identified. CONCLUSIONS: The prevalence of nontypeable strains of S. pneumoniae was higher than expected, while the number of isolates responsive to the PCV7 vaccine was surprisingly low. These results highlight the need for new vaccines that can target all S. pneumoniae strains regardless of the presence or nature of a capsule. In addition, resistance to azithromycin, erythromycin, tetracycline, and trimethoprim was greater than 10%, which may be relevant when selecting empiric treatments for ocular surface infections.
RCT Entities:
PURPOSE: Outbreaks of bacterial conjunctivitis have been linked to nontypeable strains of Streptococcus pneumoniae that lack a capsule, a key virulence factor for invasive infections. In contrast, isolates from sporadic, nonoutbreak cases of conjunctivitis were thought to be similar to invasive or nasopharyngeal isolates with respect to their capsular serotype and antibiotic resistance profile. This hypothesis was tested for 302 strains isolated during three prospective, multicenter clinical studies of bacterial conjunctivitis. MATERIALS AND METHODS:S. pneumoniae capsular serotypes were determined by agglutination assay and confirmed by the Statens Serum Institute. The presence of the cpsAB capsule genes was determined by polymerase chain reaction (PCR). Minimum inhibitory concentrations were measured for 17 antibacterial drugs by the broth microdilution method. RESULTS: Only 25 (8.3%) isolates reacted with the capsule-specific antisera and only one (0.3%) of these serotypes was covered by the capsule-specific PCV7 vaccine. The remaining 277 (91.7%) isolates were nontypeable, suggesting that they did not produce a capsule. PCR analysis indicated the loss of the capsule operon in 24/25 randomly selected nontypeable strains. Resistance rates were highest for azithromycin, trimethoprim, and tetracycline, while no resistance was detected for the fluoroquinolones, linezolid, and vancomycin. Antibiotic resistance rates were generally lower than those reported for invasive isolates, although some highly resistant or multidrug-resistant isolates were identified. CONCLUSIONS: The prevalence of nontypeable strains of S. pneumoniae was higher than expected, while the number of isolates responsive to the PCV7 vaccine was surprisingly low. These results highlight the need for new vaccines that can target all S. pneumoniae strains regardless of the presence or nature of a capsule. In addition, resistance to azithromycin, erythromycin, tetracycline, and trimethoprim was greater than 10%, which may be relevant when selecting empiric treatments for ocular surface infections.
Authors: Michael D Valentino; Abigail Manson McGuire; Jason W Rosch; Paulo J M Bispo; Corinna Burnham; Christine M Sanfilippo; Robert A Carter; Michael E Zegans; Bernard Beall; Ashlee M Earl; Elaine I Tuomanen; Timothy W Morris; Wolfgang Haas; Michael S Gilmore Journal: Nat Commun Date: 2014-11-12 Impact factor: 14.919
Authors: Mary A Carr; Dennis Marcelo; K Michael Lovell; Angela H Benton; Nathan A Tullos; Erin W Norcross; Brandon Myers; Marcus K Robbins; Hayley Craddieth; Mary E Marquart Journal: Microorganisms Date: 2022-03-25
Authors: Camille Andre; John Rouhana; Suelen Scarpa de Mello; Gabriela Rosa da Cunha; Andrew G Van Camp; Michael S Gilmore; Paulo J M Bispo Journal: Microb Genom Date: 2022-03