IMMUNOBIOLOGY OF METHICILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS - IMMUNE-RESPONSE OF RABBITS AND PATIENTS TO SYSTEMIC INFECTION

Teichoic acid (TA) and peptidoglycan (PG) extracted from Staphylococcu s aureus strains ATCC 25923 and Lafferty as well as formalinized cells of these two strains and several clinical methicillin-resistant S. au reus (MRSA) isolates were immunogenic for New Zealand White rabbits. R abbits which had recovered from experimental bacteremia due to MRSA se roconverted, i.e. demonstrated raised titers of antibodies against TA and PG of the S. aureus strain Lafferty and against whole cells (WC) a nd ultrasound cell lysates (UCL) of MRSA isolates No. 1 and 2 (represe ntative of nosocomial MRSA strain I), as determind with enzyme-linked immunosorbent assays. Furthermore, sera from 2 long-term survivor rabb its recognized four polypeptides (apparent molecular weights = 38.9, 3 3.9, 30.9, Peptidoglycan and 28.2 kDa) shared by UCL extracts from MRS A isolates No. 1 and 2, as Phagocytosis determined with immunoblots. N either normal nor immune rabbit sera augmented the bactericidal activi ty of fresh defibrinated human blood (65% v/v) against selected MRSA i solates and S. aureus strain ATCC 25923. Sera from 12 patients with do cumented systemic infection due to MRSA outbreak strain I were examine d for IgM and IgG antibodies against TA, WC, and UCL antigens. Three p atient sera exhibited raised IgM antibodies against TA; 7 of 12 patien t sera showed increased IgG anti-TA titers. Only 1 patient had a marke dly raised IgM anti-WC titer, whereas 4 and 10 of the patients had inc reased IgG titers against WC from MRSA isolates No. 1 and 2, respectiv ely. However, all 12 patients had raised Ige titers against UCL from M RSA isolate No. 2 versus 4 of 12 patients with elevated IgG titers aga inst UCL from MRSA isolate No. 1. Immunoblots with 3 selected patient sera revealed IgG antibodies to be more multifaceted than IgM antibodi es. Sera from 11 of the 12 patients contained antimicrobial drug(s); y et only 5 of these 11 sera (used at 10% v/v in broth) killed inocula o f MRSA isolate No. 43. None of the 12 patient sera (10% v/v) enhanced the bactericidal activity of human blood against selected MRSA isolate s. Neither three commercial intravenously applicable IgG preparations nor an IgG anti-alpha-hemolysin formulation (employed at 10% v/v) augm ented the bactericidal activity of fresh defibrinated human blood agai nst selected MRSA isolates comprising MRSA outbreak strain I.