The set of cell surface determinants encoded by the MHC is remarkable in that it is recognized by naive T cell populations at a sufficiently high precursor frequency to induce substantial primary proliferative responses, and the critical biologic role played by MHC products has been well established . The only other determinants capable of inducing strong proliferative responses by naive T cell...

To the Editor: In recent years, antimicrobial drug resistance in Streptococcus pneumoniae has increased worldwide and is a major health concern. Resistance to β-lac-tams and macrolides, considered to be first-line therapeutic agents, is particularly high in France and many Asian countries (1–3). Resistance to new fluoroquinolones is reported with increasing frequency, which emphasizes the need ...

BACKGROUND Antimicrobial resistance of Staphylococcus aureus especially methicillin-resistant S. aureus (MRSA) continues to be a problem for clinicians worldwide. However, few data on the antibiotic susceptibility patterns of S. aureus isolates in South Africa have been reported and the prevalence of MRSA in the KwaZulu-Natal (KZN) province is unknown. In addition, information on the characteri...

Sir, Since the early 1990s, most developed countries have experienced a rapid and substantial increase in erythromycin resistance among isolates of Streptococcus pyogenes and Streptococcus pneumoniae, probably related to the increased prescribing of this antibiotic or its novel semisynthetic derivatives. Until recently, the unique mechanism of macrolide resistance recognized in streptococci was...

The last decade was noted for the emergence and prevalence of antimicrobial agent-resistant pneumococci. Strains resistant to macrolides, chloramphenicol, and tetracycline have been registered in a number of countries (1). In some regions, resistance to macrolides prevails over the resistance to penicillin. Macrolide resistance has been reported to be high among pneumococci in Asian countries (...

Clonal complex 271 (CC271) is one of the emerging multidrug-resistant clones of Streptococcus pneumoniae, spreading in many areas of the globe (3) and including serotype 19F and the nonvaccine serotype 19A (4). CC271 pneumococci often carry dual macrolide resistance genes erm(B) and mef(E), determining a macrolide resistance phenotype (MLSB) identical to that conferred by erm(B) alone (5). We e...

Background: With the improvement of genotyping technologies and the exponentially growing number of available markers, case-control genome-wide association studies promise to be a key tool for investigation of complex diseases. However new analytical methods have to be developed to face the problems induced by this data scale-up, such as statistical multiple testing, data quality control and co...

Streptococcus agalactiae (group B streptococcus [GBS]) is the most common cause of neonatal sepsis (9). Penicillin is used for intrapartum prophylaxis, but erythromycin or clindamycin is recommended for patients allergic to penicillin (3). There are two major mechanisms of erythromycin resistance in S. agalactiae, (i) erythromycin ribosomal methylase, mediated by ermB, ermA, ermTR, or ermC, whi...

In Spain, the frequency of resistance of group A streptococci (GAS) to erythromycin was very low, increasing from 0 to 0.7% in 1989 and 1990 (1, 7) to approximately 3% in 1991 to 1994 (2). The purpose of the present study was to determine the susceptibilities of recent isolates of GAS to macrolides and, in the case of resistant isolates, to ascertain their patterns of erythromycin resistance. W...