High Proportion of Nontypeable Streptococcus pneumoniae Isolates among Sporadic, Nonoutbreak Cases of Bacterial Conjunctivitis

Autor:	Wolfgang Haas, Christine K. Hesje, Timothy W. Morris, Christine M Sanfilippo
Rok vydání:	2011
Předmět:	Adult Male Adolescent Biology medicine.disease_cause Pneumococcal Infections Virulence factor Disease Outbreaks Microbiology Conjunctivitis Bacterial Young Adult Cellular and Molecular Neuroscience Antibiotic resistance Vaccine strain Streptococcus pneumoniae medicine Humans Prospective Studies Child Aged Aged 80 and over Bacterial Conjunctivitis Incidence Infant Outbreak Middle Aged Prognosis Virology United States Sensory Systems Anti-Bacterial Agents Ophthalmology Child Preschool Female Conjunctiva Follow-Up Studies
Zdroj:	Current Eye Research. 36:1078-1085
ISSN:	1460-2202 0271-3683
DOI:	10.3109/02713683.2011.624670
Popis:	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.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.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.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.
Databáze:	OpenAIRE
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