Heterogeneous resistance to vancomycin and teicoplanin among Staphylococcus spp. isolated from bacteremia

Abstract

This study evaluated the BHIA screening method with 4 or 6 μ μ μ μ μg/mL of vancomycin to detect glycopeptides heteroresistant staphylococci strains isolated from bacteremia. A total of 213 staphylococci strains were isolated from 106 patients between October/2001 and November/2002 in a tertiary hospital in Rio de Janeiro city. Fifty-seven (53.8%) patients presented Staphylococcus aureus, while coagulase-negative staphylococci (CNS) were isolated from 49 (46.2%). Resistance rates for oxacillin of 26.3% and 81.6% were found for the staphylococci isolates, respectively. Thirteen CNS isolated from nine (8.5%) patients grew on agar screening with 4 μ μ μ μ μg/mL of vancomycin and showed heterogeneous profiles of resistance for vancomycin and teicoplanin by the population analysis profile method. Only 30.8% of them grew at the concentration 6 μ μ μ μ μg/mL. Bacterial infection and use of antimicrobial therapy were common among these patients. Alert about the emergence of oxacillin-resistant staphylococci presenting heteroresistance to glycopeptides is important in order to achieve judicious use of antimicrobials. Vancomycin agar screening test could help to confirm the presence of these isolates in hospitals.

The occurrence and dissemination of methicillin and vancomycin-resistant Staphylococcus in samples from patients and health professionals of a university hospital in Recife, State of Pernambuco, Brazil

“…The remaining samples were from professionals, two of which were classifi ed as the same ribotype (isolates 101NFLn and 110NFVn, Figure 1), suggesting that they are the same strain. Studies indicate that resistance to vancomycin should be determined by more sensitive techniques, such as plate screening, E-test, microdilution and genotype detection [17][18][19][20] . In Brazil, intermediate resistance to vancomycin in patients has been described, but few studies have reported colonization of health professionals by these strains 32 .…”

“…A 1µL platinum wire loop was dipped in the suspension, and the bacteria were seeded in an area with a 10-15mm diameter on plates with BHI agar medium containing 6μg/mL vancomycin (Oxoid). The plates were incubated at 35°C for 24h and 48h and then read, considering that >1 colony = resistance [18][19][20] . For quality control, the standard strains Enterococcus faecalis ATCC 29212 -sensitive and Enterococcus faecalis ATCC 51299 -resistant were used.…”

Pentaclethra macroloba tannins fractions active against methicillin-resistant staphylococcal and Gram-negative strains showing selective toxicity

“…In Brazil, methicillin-resistant Staphylococcus aureus (MRSA) is responsible for approximately 43% of these infections (Sader et al, 2004). Coagulase-negative staphylococci (CNS) is also recognized as a important nosocomial pathogen around the world, highlighting the multiresistant Staphylococcus epidermidis and Staphylococcus haemolyticus as the most isolated organisms from bacteremia (Nunes et al, 2007) and infections related to implanted medical devices (Uçkay et al, 2009) Resistance to methicillin is relevant in these pathogens because is related to resistance to other β-lactams and can be associated with resistance to other classes of antimicrobials (Feng et al, 2008).…”

“…(Nunes et al, 2007;NascimentoCarvalho et al, 2008), and Gram-negative bacilli Hsueh et al, 2002;Touati et al, 2009;Nogueira et al, 2006) can make difficult the treatment of infectious diseases. Then, as a new therapeutic option we evaluated the antibacterial activity of P. macroloba extracts against Gram-positive and Gram-negative hospital bacteria as well as against reference strains, establishing the minimum inhibitory activity of the active fractions.…”

Heteroresistance

“…Kim et al, 2002;Marchese et al, 2000;Reverdy et al, 2001;Wang et al, 2004) have proved that heteroresistance to vancomycin among MRSA was maybe ignored or underestimated but not absent. Furthermore, since early VISA isolates in the USA were resistant to teicoplanin too (Appelbaum, 2007), and reduced susceptibility (Park et al, 2000) or heterogeneous resistance (Nunes et al, 2007) to this drug were also reported, the term glycopeptide-intermediate S. aureus (GISA) has been added to indicate a broader resistance profile.…”