In vitro antibacterial activity of 429 clinical isolates of gram-positive cocci was tested against citreamicin-alpha (LL-E 19085-alpha) by the agar dilution method. The microorganisms consisted of 313 isolates of staphylococci and 116 strains of streptococci. In vitro activity of citreamicin-alpha was compared with ampicillin, augmentin, cephalothin, erythromycin and vancomycin. MICs of citreamicin-alpha for staphylococci ranged between 0.12-4.0 μg/ml and 0.03-0.12 μg/ml for Streptococcus pyogenes. Enterococci, however, were relatively more resistant, requiring 2.0 μg/ml of this drug to inhibit 64% of the 62 isolates tested. In vitro activity of this antibacterial agent was far superior to that of ampicillin, augmentin, cephalothin and erythromycin, but equal to or slightly inferior to that of vancomycin.

Cefdinir is a new orally active cephalosporin which is undergoing in vitro and in vivo evaluations. Using the standard agar dilution method we compared the in vitro activity of this drug with other (3-lactam antibiotics against clinical isolates or Ente-robacteriaceae (625 strains), Pseudomonas aeruginosa (68 strains), Xanthomonas maltophilia (36 strains), Acinetobacter (52 strains), Aeromonas hydrophilia (47 strains), staphylococci (364 strains) and enterococci (50 strains). Against most members of Enterobacteriaceae, Acinetobacter and A. hydrophilia, cefdinir showed excellent activity, inhibiting 94% of these isolates at ≤ 32 ug/ml. Like other oral drugs of its class, it had little activity against P. aeruginosa andX. maltophilia. All the 120 isolates of methicillin-susceptible Staphylococcus aureus were inhibited by < 1.0 ug/ml of cefdinir whereas 80% of methicillin-resistant S. aureus had a minimum inhibitory concentration of > 32 ug/ml. Of the 50 isolates of enterococci tested, 94% were inhibited by ≤16.0 ug/ml of cefdinir. Against Enterobacteriaceae, its activity was superior to any oral drug tested. With the exception of vancomycin, the in vitro activity of cefdinir was superior or comparable to other antibiotics tested against methicillin-susceptible S. aureus, coagulase-negative staphylococci and enterococci.

A total of 1,007 clinical isolates from a tertiary care center were tested against RU 29246, ampicillin, cephalothin, cefoxitin, ceftazidime, Augmentin, oxacillin, piperacillin, gentamicin, amikacin and vancomycin. Bacteria tested consisted of 479 strains of Entewbacteriaceae, 64pseudomonads, 18Xanthomonas, 42 other gram-negative bacilli, 56 enterococci and 348 isolates of staphylococci. RU 29246 showed excellent in vitro activity inhibiting > 90% of Escherichia coli, Klebsiella pneumoniae, K. oxytoca, Enterobacter, Proteus mirabilis, Providencia, Morganella, Salmonella, Shigella, Aeromonas hydrophila, and methicillin-susceptible Staphylococcus aureus at an MIC of 0.5-1.0 mg/l. Seventy-seven percent coagulase-negative staphylococci had an MIC of 1.0-4.0 mg/l. All strains of Pseudomonas aeruginosa and X. maltophilia were resistant to RU 29246. Fifty-six percent of the enterococcal isolates were inhibited by 1.0-16.0 mg/l of RU 29246.

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) is on the rise, especially in nosocomial and intravenous-drug-abuse-related infections, with a concomitant increase in morbidity, mortality and health care costs. At present the drug of choice, vancomycin, which must be administered intravenously, is expensive and can cause serious side effects in vancomycin-intolerant patients. Recently, minocycline has received much attention as an antibiotic to combat the increasing frequency of MRSA-related infections. We tested 102 recent clinical isolates of MRSA from tertiary-care patients and found none to be resistant to minocycline, with minimum inhibitory concentrations of < 1-2 μg/ml. The only other drug that inhibited all the strains was vancomycin, followed by ciprofloxacin (87%), clindamycin (55%) and chloramphenicol (52%). Gentamicin, β-lactams, tetracycline and trimethoprim-sulfamethoxazole had little or no activity against our isolates of MRSA.

Since fluoroquinolones have generated much interest because of their excellent in vitro and in vivo activity, their pharmacokinetic properties, oral dosing and intracellular penetration, we tested the susceptibility of 146 recent clinical isolates of Brucella melitensis against eight 4-quinolone drugs and five conventional drugs. The drugs tested included ciprofloxacin, norfloxacin, temafloxacin, sparfloxacin, fleroxacin, pefloxacin, lomefloxacin, CI-960, tetracycline, gentamicin, streptomycin rifampicin and trimethoprim-sulfamethoxazole. All the isolates were susceptible to the eight quinolones tested, with an MIC-90 ranging between 0.12 mg/L to 2.0 mg/L depending on the drug. Lowest MCIs were observed with CI-960 and highest temafloxacin and sparfloxacin. One isolate which had developed resistance to ciprofloxacin while the patient was being treated with this drug exhibited cross-resistance to all the members of the family.SMH Qadri, J Akhter, Y Ueno, H Saldin, In Vitro Activity of Eight Fluoroquinolones Against Clinical Isolates of Brucella Melitensis. 1993; 13(1): 37-40 Over the last decade the newer preparations of fluoroquinolones have advanced the field of antimicrobial chemotherapy significantly [1]. These are all derivatives of nalidixic acid and exert their activity through inhibition of DNA synthesis by DNA gyrase. The first breakthrough arrived with the development of norfloxacin, a second generation quinolone, which exhibited enhanced activity as an orally active agent for urinary tract infections. Further developments arrived with ciprofloxacin and later by third generation quinolones such as sparfloxacin, temafloxacin, and CI-960. The trend in the synthesis of newer third generation agents has been to increase the number of fluorine residues, resulting in extended spectrum of activity, better penetration and improved pharmacokinetic properties [2,3]. Intracellular penetration of fluoroquinolones provides an interesting alternative in the treatment of intracellular parasites such as Salmonella and Brucella [4,5]. Since brucellosis is endemic in Saudi Arabia, we tested the in vitro activity of eight fluoroquinolones against 146 clinical isolates of B. melitensis. Material and MethodsA total of 146 isolates of B. melitensis were used in this study. In order to avoid duplication of strains from the same patient, only one strain for each individual patient was tested. The bacteria were isolated from blood, mitral valve, joint fluid or tissues of patients at King Faisal Specialist Hospital and Research Centre (KFSH&RC) which is a 550-bed tertiary care referral facility in Riyadh. All isolates were identified using conventional techniques and consisted of 94 isolates of biotype 1 and 52 isolates of biotype 3 [6]. Minimum inhibitory concentrations of the fluoroquinolones and other antimicrobials were determined by agar dilution method according to the standard In Vitro Activity of Eight Fluoroquinolones Against Clinical Isolates of Brucella MelitensisAnnals of Saudi Medicine, Vol 13 No. 1;1993 method ...