Argentinean collaborative multicenter study on the in vitro comparative activity of piperacillin-tazobactam against selected bacterial isolates recovered from hospitalized patients

Casellas, José María; Tomé, Gabriella; Bantar, Carlos; Bertolini, Pamela; Blazquez, Nestor; Borda, Noemí; Couto, Elsa; Cudmani, Norma; Guerrera, Josefina; Juárez, María Josefina; López, Teresa; Littvik, Ana; Méndez, Emilce; Notario, Rodolfo; Ponce, Graciela; Quinteros, Mirta; Salamone, Francisco; Sparo, Mónica; Sutich, Emma; Vaylet, Susana; Wolff, Lidia

doi:10.1016/s0732-8893(03)00131-7

Cited by 20 publications

(11 citation statements)

References 15 publications

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“…Further increasing the inoculum to 10 8 CFU/ml substantially prolonged the time to 99.9% killing, i.e., from 1 h to 24 h at 10ϫ the MIC, by testing with VRSA-MI. This inoculum effect is similar to that described in previous reports on beta-lactams and glycopeptides and may be a reflection of CSA-13's mechanism of action, given that the literature has suggested that antimicrobials targeting the cell wall have been associated with an inoculum effect (3,21). Combination time-kill studies demonstrated that CSA-13 is a potent agent when it is used by itself.…”

Section: Discussionsupporting

confidence: 85%

Antimicrobial Activities of Ceragenins against Clinical Isolates of Resistant Staphylococcus aureus

Chin

Rybak

Cheung

et al. 2007

Antimicrob Agents Chemother

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The rise in the rates of glycopeptide resistance among Staphylococcus aureus isolates is concerning and underscores the need for the development of novel potent compounds. Ceragenins CSA-8 and CSA-13, cationic steroid molecules that mimic endogenous antimicrobial peptides, have previously been demonstrated to possess broad-spectrum activities against multidrug-resistant bacteria. We examined the activities of CSA-8 and CSA-13 against clinical isolates of vancomycin-intermediate S. aureus (VISA), heterogeneous vancomycinintermediate S. aureus (hVISA), as well as vancomycin-resistant S. aureus (VRSA) and compared them to those of daptomycin, linezolid, and vancomycin by susceptibility testing and killing curve analysis. We also examined CSA-13 for its concentration-dependent activity, inoculum effect, postantibiotic effect (PAE), and synergy in combination with various antimicrobials. Overall, the MICs and minimal bactericidal concentrations of CSA-13 were fourfold lower than those of CSA-8. Time-kill curve analysis of the VRSA, VISA, and hVISA clinical isolates demonstrated concentration-dependent bactericidal killing. An inoculum effect was also observed when a higher starting bacterial density was used, with the time required to achieve 99.9% killing reaching 1 h with a 6-log 10 -CFU/ml starting inoculum, whereas it was >24 h with a 8-to 9-log 10 -CFU/ml starting inoculum with 10؋ the MIC (P < 0.001). A concentration-dependent PAE was demonstrated with CSA-13, nearly doubling from 2؋ to 4؋ the MIC (P ‫؍‬ 0.03). With respect to the CSA-13 antimicrobial combinations, time-kill curve analysis showed no difference in the log 10 CFU/ml at 24 h for the majority of the organisms tested. However, early synergy at 4 to 8 h was detected against the VRSA Pennsylvania strain (2002) when CSA-13 was tested in combination with gentamicin, while early additivity was demonstrated against all of the other organisms.

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Section: Discussionsupporting

confidence: 85%

Antimicrobial Activities of Ceragenins against Clinical Isolates of Resistant Staphylococcus aureus

Chin

Rybak

Cheung

et al. 2007

Antimicrob Agents Chemother

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“…However, ESBL rates among Proteus mirabilis isolates differ widely in different continents. They were lower in northern South America while very frequent in South America as in Argentina (33% to 40%) [8,10,24] (6.2%) than in eastern and southern Europe (21.3% and 20.5%, respectively) [11].…”

Section: Epidemiological and Geographical Distribution Of Extended‐spmentioning

confidence: 99%

“…However, there are marked geographical differences. In Colombia, TEM (and SHV) ESBLs are widely prevalent among E. coli and actually seldom found [21] in southern South America [24].…”

Section: Tem-type Esblsmentioning

confidence: 99%

Prevalence of extended-spectrum β-lactamases in South America

Villegas

Kattan

Quinteros

et al. 2008

Clinical Microbiology and Infection

110

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In South American countries, the class A extended-spectrum beta-lactamases (ESBLs) so far recognised belong to the CTX-M, Pseudomonas Extended Resistance (PER), SHV and TEM families. ESBL rates in South America are among the highest in the world, probably due to multiple factors. SHV- and TEM-type ESBLs have been frequently encountered, but CTX-M is endemic and widely dominant. PER-type ESBLs seem to be restricted to the southern 'cone' of South America. Community-acquired ESBLs are starting to appear.

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“…In addition, the type of enzymes that are prevalent is different, because the CTX-M class appears to be the dominant class in some countries, notably Argentina (2,10,17). CTX-M class enzymes have not been reported previously in Colombia.…”

mentioning

confidence: 96%

“…These enzymes may be even more common than current reports suggest due to inadequate detection, because some laboratories may not be screening correctly. CTX-M enzymes hydrolyze cefotaxime and ceftriaxone more efficiently than ceftazidime, so that screening with ceftazidime alone may easily miss these enzymes (10,17). Nevertheless, the activity of these enzymes against ceftazidime is highly variable; some strains appear susceptible, while others are frankly resistant.…”

mentioning

confidence: 99%