- Widespread detection of PER-1-type extended-spectrum beta-lactamases among nosocomial Acinetobacter and Pseudomonas aeruginosa isolates in Turkey: a nationwide multicenter study. Vahaboglu, H., Oztürk, R., Aygün, G., Coşkunkan, F., Yaman, A., Kaygusuz, A., Leblebicioglu, H., Balik, I., Aydin, K., Otkun, M. Antimicrob. Agents Chemother. (1997)