In vitro activity of 79 antimicrobial agents against Corynebacterium group D2

Abstract

Corynebacterium group D2 (CGD2) is involved in urinary tract infections in patients with underlying predisposing factors. This microorganism is highly resistant to a number of antimicrobial agents. We tested the activities of 79 antimicrobial agents against CGD2. (8-Lactams, aminoglycosides, and macrolides were ineffective. Fluorinated quinolones showed irregular activities, ofloxacin being the most active one. Doxycycline, rifampin, and mainly glycopeptides (vancomycin and teicoplanin) were the most active antibiotics against CGD2.Corynebacterium group D2 (CGD2) is involved in the etiology of urinary tract infections (UTIs) in patients with underlying predisposing factors, such as urinary tract instrumentation, surgery, or malignancy (1). CGD2 has also been involved in the origin of phosphate-encrusted cystitis (10, 11) and in sepsis in compromised hosts (3). This group has been shown to be resistant to most antibiotics used for the treatment of UTIs (9), the utilization of glycopeptides being frequently necessary.We studied the in vitro activities of 79 antimicrobial agents against CGD2 in order to find therapeutic alternatives useful for the treatment of UTIs caused by this microorganism.The antibiotics tested, kindly provided by their manufacturers, were penicillin, ampicillin, amoxicillin, carbenicillin, ticarcillin, azlocillin, mezlocillin, piperacillin, cloxacillin, mecillinam, temocillin, amoxicillin-clavulanic acid, sulbactam-ampicillin, piperacillin-tazobactam, ticarcillin-clavulanic acid, cefazolin, cefamandole, cefuroxime, cefotetan, cefonicid, cefaclor, cefoxitin, cefotaxime, cefsulodin, cefetamet, cefterame, latamoxef, ceftizoxime, cefoperazone, cefbuperazone, cefpirome, CGP-31608/WS (Ciba-Geigy), CGP-22495 (Ciba-Geigy), CGP-31523 (Ciba-Geigy), ICI-194008 lysed horse blood was used). The inoculum was prepared in Mueller-Hinton broth from a 48-h growth on Mueller-Hinton 5% sheep blood agar, adjusted to a turbidity equivalent to that of a 0.5 McFarland standard, and diluted 1:10. The inoculation of the agar plates was performed by using a Steer's replicator, the final inoculum on the media being approximately 104 CFU per spot. Plates were incubated for 48 h at 35°C in room air, since after 24 h of incubation, the control plates (the same strains inoculated on the same blood agar without antibiotics) occasionally showed very faint growth or had no visible growth. The growth on these plates after 48 h was always satisfactory. The MIC was defined as the lowest concentration of antibiotic that suppressed visible bacterial growth. Single colonies, faint hazes, and skip plates were disregarded.Results are shown in Table 1 and confirm the high resistance of CGD2 to a wide number of antimicrobial agents (6). CGD2 was resistant to all of the penicillins and combinations of penicillin and ,B-lactamase inhibitor tested. No strain was inhibited by any of these compounds and combinations at 128 ,ug/ml. To all of the cephalosporins, including the most recently developed ones and those active against other gram-...

The lifestyle of Corynebacterium urealyticum derived from its complete genome sequence established by pyrosequencing

“…Multiresistance to clinically relevant antibiotics is a prominent feature of the majority of C. urealyticum strains (García-Rodriguez et al, 1991;Funke et al, 1997). Evaluation of the complete genome sequence of C. urealyticum DSM7109 revealed the presence of an ErmX determinant encoding a 23S rRNA adenine N-6-methyltransferase (Roberts et al, 1999).…”

“…Encrusted cystitis may require endoscopic resectioning of encrustations and antibiotic therapy for permanent cure (Funke et al, 1997;van Hooland et al, 2005). The majority of C. urealyticum strains are, however, highly resistant to a large number of antibiotics, including ␤-lactams, aminoglycosides, and macrolides (García-Rodriguez et al, 1991;Soriano et al, 1995;Martínez-Martínez et al, 1998), although the glycopeptides vancomycin and teicoplanin remain universally active against these isolates (Soriano et al, 1991(Soriano et al, , 1998Lagrou et al, 1998). It has been suggested that the appearance of multiresistant C. urealyticum strains is favored by the use of antibiotics in hospital settings and that these strains are likely to be acquired by inpatients directly from the bacterial flora present in the hospital environment (Garcia-Bravo et al, 1996).…”

Comparative in vitro activities of new quinolones against coryneform bacteria

“…Considering these values, an initial report (6) showed that all strains of C. jeikeium were susceptible to CIP, but a more recent study (9) showed that only 36% of C. jeikeium strains were susceptible to this fluoroquinolone. Similarly, initial data concerning C. urealyticum (10) showed that all strains tested were susceptible to OFL; in a later report (2) …”

Activities of ABT-773 against Listeria monocytogenes and Coryneform Bacteria of Clinical Interest

“…It is critical that studies of the activities of antimicrobial agents be based on testing microorganisms identified according to the new taxonomic criteria, in order to really obtain clinically significant information and to allow the comparison of data obtained from different laboratories (3,5,13,19,24). Unfortunately, there is yet no standardized methodology for susceptibility testing of coryneform bacteria.…”

“…only the category of susceptibility to ampicillin and penicillin has been suggested (16). There is scant information on the activities of antimicrobial agents against coryneform bacteria (4)(5)(6)9). C. jeikeium, C. urealyticum, and C. amycolatum are usually multiresistant organisms, and only glycopeptides remain universally active against these species (4-6, 18, 19, 22, 23).…”