Mediterranean clone of penicillin-susceptible, multidrug-resistant serotype 6B Streptococcus pneumoniae in Greece, Italy and Israel

In 1996, 19 isolates of serotype 6B Streptococcus pneumoniae with a unique resistance pattern were found in carriers attending daycare centres in Patr as, Southwestern Greece. These isolates were penicillin susceptible but res istant to chloramphenicol, tetracycline, erythromycin, clindamycin and trim ethoprim-sulphamethoxazole. Subsequently, isolates with the same characteri stics were found in 23 additional carriers in central and southern Greece i n 1997-98 as well as in 19 carriers in central Italy in 1997, and in seven carriers in southern Israel in 1998. Carriers were all children under 6 yea rs of age, attending daycare centres or outpatient hospital visits. The rel atedness of the isolates was determined on representative isolates from the three countries by pulsed-field gel electrophoresis of SmaI digests of chr omosomal DNA. Most Greek isolates were identical to each other, while isola tes from Italy and Israel showed one to three band differences, with all is olates being closely related to each other as well as to the isolates from Greece. We have therefore documented the presence of this unique clone of S . pneumoniae in these three countries and have named this the 'Mediterranea n' clone. While isolates appear to have a common origin, their source and d irection of spread are unknown. However, isolates from Italy showed the mos t diversity, suggesting that this clone had been present in that country fo r a longer period than it had been in Greece. (C) 2000 Elsevier Science B.V . and International Society of Chemotherapy. All rights reserved.