Objectives: There is a lack of microbiological gold standard for the diagnosis of Cardiac Device Infections (CDIs). Aim of the study was to analyze the role of sonication before the culture in the diagnosis of CDIs and asymptomatic bacterial colonization. Methods: Over a 6 months period, a total of 80 explanted devices (40 generators, 5 grafts and 35 lead tips) collected from 20 subjects with CDI and 20 subjects without CDI was analyzed. The removed samples were inoculated in Trypticase soy broth (TSB) for 24 h and cultured with traditional methods. In addition, they were vortexed for 30s, sonicated for 5 min at a frequency >20kHz and vortexed again for 30 s, using the BactoSonic (BANDELIN electronic GmbH & Co. KG). Statistical analysis were performed using STATA 9 software (STATA corp. LP, College Station, Texas, USA). Results: Overall sensitivity of sonication fluid culture was higher than standard culture and intra operative pocket swab culture. Among all the removed devices, culture after sonication yielded bacteria in 77% of the components compared with 60% of standard culture (p=0.001). Coagulase-negative Staphylococci (CoNS) accounted for 72% of the strains whereas Staphylococcus aureus and gram-negative bacilli were found in 4% and 8% of the total, respectively. No bacterial detection occurred in 8% of CDI. Culture after sonication detected more bacteria than standard method (29,91x10'4 UFC/ml vs 21,10x10'4 UFC/ml, p=0.019), especially when the bacterial amount with TSB was <104 UFC/ml (p=0.0002). The difference in the bacterial cell count between the two methods was particularly noticeable for the electrodes (19,41x10'4 UFC/ml vs 66,90x10'3 UFC/ml, p=0.018) rather than for the generators (47,77x10'4 UFC/ml vs 46,55x10'4 UFC/ml, p=0.7). Previous antibiotic therapy had no effect on the diagnostic value of sonication fluid culture (p=0.9). In the control group, standard culture yielded bacteria in 4/20 subjects (20%) compared with 8/20 (40%) of sonication fluid culture. The best cell-count value which discriminated infected from non-infected devices in sonication fluid culture was 10'4 UFC/ml. Conclusions: The sensitivity of culture after sonication is higher than standard culture, in both infected and non-infected cardiac devices. Sonication of explanted devices may represent a useful tool to improve microbiologic diagnosis of CDIs and asymptomatic bacterial colonization
Sonication of explanted devices improves the pathogen detection in cardiac device infections / Oliva, Alessandra; Nguyen, BICH LIEN; Mascellino, Maria Teresa; Fernanda, Chiarini; Mengoni, Fabio; Ciccaglioni, Antonio; Fattorini, Fabrizio; D'Abramo, Alessandra; Iannetta, Marco; Mastroianni, Claudio Maria; Vullo, Vincenzo. - In: CLINICAL MICROBIOLOGY AND INFECTION. - ISSN 1198-743X. - STAMPA. - (2012), pp. -----. (Intervento presentato al convegno 22nd ECCMID 2012 tenutosi a London nel 31 march-3 april 2012).
Sonication of explanted devices improves the pathogen detection in cardiac device infections
OLIVA, ALESSANDRA;NGUYEN, BICH LIEN;MASCELLINO, Maria Teresa;MENGONI, Fabio;CICCAGLIONI, Antonio;FATTORINI, Fabrizio;D'ABRAMO, ALESSANDRA;IANNETTA, MARCO;MASTROIANNI, Claudio Maria;VULLO, Vincenzo
2012
Abstract
Objectives: There is a lack of microbiological gold standard for the diagnosis of Cardiac Device Infections (CDIs). Aim of the study was to analyze the role of sonication before the culture in the diagnosis of CDIs and asymptomatic bacterial colonization. Methods: Over a 6 months period, a total of 80 explanted devices (40 generators, 5 grafts and 35 lead tips) collected from 20 subjects with CDI and 20 subjects without CDI was analyzed. The removed samples were inoculated in Trypticase soy broth (TSB) for 24 h and cultured with traditional methods. In addition, they were vortexed for 30s, sonicated for 5 min at a frequency >20kHz and vortexed again for 30 s, using the BactoSonic (BANDELIN electronic GmbH & Co. KG). Statistical analysis were performed using STATA 9 software (STATA corp. LP, College Station, Texas, USA). Results: Overall sensitivity of sonication fluid culture was higher than standard culture and intra operative pocket swab culture. Among all the removed devices, culture after sonication yielded bacteria in 77% of the components compared with 60% of standard culture (p=0.001). Coagulase-negative Staphylococci (CoNS) accounted for 72% of the strains whereas Staphylococcus aureus and gram-negative bacilli were found in 4% and 8% of the total, respectively. No bacterial detection occurred in 8% of CDI. Culture after sonication detected more bacteria than standard method (29,91x10'4 UFC/ml vs 21,10x10'4 UFC/ml, p=0.019), especially when the bacterial amount with TSB was <104 UFC/ml (p=0.0002). The difference in the bacterial cell count between the two methods was particularly noticeable for the electrodes (19,41x10'4 UFC/ml vs 66,90x10'3 UFC/ml, p=0.018) rather than for the generators (47,77x10'4 UFC/ml vs 46,55x10'4 UFC/ml, p=0.7). Previous antibiotic therapy had no effect on the diagnostic value of sonication fluid culture (p=0.9). In the control group, standard culture yielded bacteria in 4/20 subjects (20%) compared with 8/20 (40%) of sonication fluid culture. The best cell-count value which discriminated infected from non-infected devices in sonication fluid culture was 10'4 UFC/ml. Conclusions: The sensitivity of culture after sonication is higher than standard culture, in both infected and non-infected cardiac devices. Sonication of explanted devices may represent a useful tool to improve microbiologic diagnosis of CDIs and asymptomatic bacterial colonizationI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
