Identification of Streptococcus pneumoniae: Development of a Standardized Protocol for Optochin Susceptibility Testing Using Total Lab Automation.

Purpose. Optochin susceptibility is one parameter used in the laboratory to identify Streptococcus pneumoniae. However, a single standardized procedure does not exist. Optochin is included neither in the current EUCAST breakpoint tables nor in the CLSI performance standards for antimicrobial susceptibility testing. We wanted to establish an evidence-based protocol for optochin testing for our Total Lab Automation. Methods. We tested seven different agars and four different reading time points (7 h, 12 h, 18 h, and 24 h). To accommodate for serotype diversity, all tests were done with 99 different strains covering 34 different serotypes of S. pneumoniae. We calculated a multivariable linear regression using data from 5544 inhibition zones. Results. Reading was possible for all strains at 12 h. Agar type and manufacturer influenced the size of the inhibition zones by up to 2 mm and they varied considerably depending on serotype (up to 3 mm for serotype 3). Depending on agar and reading time point, up to 38% of inhibition zones were smaller than the cut-off of 14 mm; that is, the result of the test was false-negative. Conclusions. Shortening incubation time from 24 h to 12 h for optochin susceptibility testing is feasible. Agar and incubation time have to be chosen carefully to avoid false-negative results.

Streptococcus pneumoniae as an agent of urinary tract infections - a laboratory experience from 2010 to 2014 and further characterization of strains.

Streptococcus pneumoniae is a rare cause of urinary tract infection. Between January 2010 and December 2014, 26 urine samples from 18 different patients contained S. pneumoniae at the Department for Infectious Diseases, University Hospital of Heidelberg. Patient age varied between three and 72 years. 13 patients were male and five were female. Past medical histories of 16 patients were available. Eight patients had a past medical history of renal transplant and four patients had other renal dysfunctions. Further analyses of the isolates revealed that the aspect of colonies is more resembling S. mitis than invasive isolates of S. pneumoniae. Optochin disk diameters tend to be 14 mm or smaller. Identification using MALDI-TOF or VITEK2 identification cards was accurate. Only 2 isolates showed a decreased susceptibility towards penicillin (MIC = 0.5 mg/L). Eight different serotypes were identified using a PCR approach as well Neufeld-Quellungs reaction.

Comparison of microbiomes from different niches of upper and lower airways in children and adolescents with cystic fibrosis.

Changes in the airway microbiome may be important in the pathophysiology of chronic lung disease in patients with cystic fibrosis. However, little is known about the microbiome in early cystic fibrosis lung disease and the relationship between the microbiomes from different niches in the upper and lower airways. Therefore, in this cross-sectional study, we examined the relationship between the microbiome in the upper (nose and throat) and lower (sputum) airways from children with cystic fibrosis using next generation sequencing. Our results demonstrate a significant difference in both α and ß-diversity between the nose and the two other sampling sites. The nasal microbiome was characterized by a polymicrobial community while the throat and sputum communities were less diverse and dominated by a few operational taxonomic units. Moreover, sputum and throat microbiomes were closely related especially in patients with clinically stable lung disease. There was a high inter-individual variability in sputum samples primarily due to a decrease in evenness linked to increased abundance of potential respiratory pathogens such as Pseudomonas aeruginosa. Patients with chronic Pseudomonas aeruginosa infection exhibited a less diverse sputum microbiome. A high concordance was found between pediatric and adult sputum microbiomes except that Burkholderia was only observed in the adult cohort. These results indicate that an adult-like lower airways microbiome is established early in life and that throat swabs may be a good surrogate in clinically stable children with cystic fibrosis without chronic Pseudomonas aeruginosa infection in whom sputum sampling is often not feasible.