277
DIAGN MICROBIOL INFECT DIS 1990;13:277-279
Antibacterial Activity of Lomefloxacin Against Brucella melitensis S.M. Hussain Qadri, Sultan A1-Sedairy, and Yoshio Ueno
The in vitro activity of Iomefloxacin was tested against 114 clinical isolates of Brucella melitensis. Comparison was made with ciprofloxacin, tetracycline, gentamicin, rifampin, and trimethoprim-sulfamethoxazole. Lomefloxacin inhibited 113 (99.1%) of the 114 strains tested at ~ 0.5 tzg/ml. It was corn-
parable to ciprofloxacin, tetracycline and gentamicin in antimicrobial potency. One strain that was previously susceptible to ciprofloxacin and had become resistant after the patient was treated with ciprofloxacin showed cross-resistance to lomefloxacin.
The newer preparations of fluoroquinolones have advanced the field of antimicrobial chemotherapy significantly. Their mode of action consists of inhibiting the supercoiling activity of the DNA gyrase, thus depressing the DNA and RNA synthesis and resulting in the killing of susceptible organisms (Paton and Reeves, 1988). Lomefloxacin is one of the new members of the fluorinated quinolones. It is a synthetic difluoroquinolone with a 3-piperazine moiety and is suitable for oral administration, with a half-life of - 8.5 hr. Its in vivo and in vitro effectiveness against a wide range of Gram-positive and Gram-negative bacilli, excluding Brucella, has been confirmed (Weinstein 1988; Finch et al., 1988; Chin et al., 1988). We believe that this is the first report on the susceptibility of Brucella melitensis to lomefloxacin. Other antimicrobials, such as ciprofloxacin, tetracycline, gentamicin, trimethoprim-sulfamethoxazole, and rifampin, were included for comparison. Clinical isolates from the blood, synovial fluid, mitral valve, or other tissues of 113 patients with B. melitensis infection were used and identified by standard methods (Hausler et al., 1985). Minimal inhib-
itory concentrations (MIC) were determined by broth dilution according to the method of Hall and Marion (1970), using Mueller-Hinton broth and an inoculum of 105 to 106 CFU/rrfl. The effect of antibacterial agents in combination was tested by the method of Schoenknecht et al., (1985). In all cases, incubation was at 36°C for 48 hr in a 5% CO2 incubator. The antibacterial activity of lomefloxacin, along with ciprofloxacin and four conventional agents against 114 clinical isolates of B. melitensis, is shown in Table 1. Of the 114 isolates tested, 113 were inhibited by ~ 0.5 ~g/ml of lomefloxacin, which was slightly more potent than ciprofloxacin. The parent strain of one of the resistant isolates with an MIC of > 5.0 ~g/ml to lomefloxacin and ciprofloxacin was originally susceptible to both drugs with an MIC of 0.06 ~g/ml. However, while the patient was being treated with ciprofloxacin, the organism developed resistance to ciprofloxacin and was cross-resistant to lomefloxacin. The isolate remained susceptible to tetracycline, gentamicin, rifampin, and trimethoprim-sulphamethoxazole. All of the isolates were inhibited by ~ 0.5 ~g/ml of both tetracycline and gentamicin. Trimethoprim-sulphamethoxazole and rifampin inhibited all of the isolates at a concentration of ~ 1.0 ~g/ml. Drug interaction studies (synergy) were performed using lomefloxacin in combination with conventional drugs. Lomefloxacin did not show any in vitro synergy with tetracycline, gentamicin, rifampin, or trimethoprim-sulphamethoxazole against these isolates. B. melitensis is a causative agent of brucellosis (un-
From the King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia Address reprint requests to: Dr. Syed M.H. Qadri, King Faisal Specialist Hospital and Research Centre, P. O. Box 3354, Riyadh 11211, Saudi Arabia. Received December 8, 1989; revised and accepted December 11, 1989. © 1990 Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0732-8893/90/$3.50
278
TABLE 1.
S.M. Hussain Qadri et al.
Susceptibility of 114 Clinical Isolates of B. melitensis to Lomefloxacin and Five Other Drugs MIC (~g/ml) (cumulative numbers)
Drug Lomefloxacin Ciprofloxacin Tetracycline Gentamicin Trimethoprimsulfamethoxazole ° Rifampin
0.03
0.06
0.12
0.25
0.5
1.0
14
26 21 13
54 42 51 6 8
101 97 92 103 47
113 113 114 114 84
114
8
65
90
114
aThe ratio of trimethoprim-sulfamethoxazolewas 1:19. dulant fever) that occurs primarily in goats and sheep. It was first identified in 1904 when it was isolated from the milk and urine of healthy goats. The infection is generally rare in man, with most of the cases resulting as an occupational hazard. However, it is endemic in most of the developing countries, including Saudi Arabia, mainly due to the consumption of uninspected meat and raw unpasteurized goat and sheep milk in the rural areas. This organism has remained susceptible to conventional antimicrobials. The relapse rate with different drugs has been reported to range between 5% and 70% (Buchanan et al., 1974; Farrell et al., 1976; Rizzo-Naudi et al., 1967). A probable explanation of these relapses may be relative inaccessibility of the antibacterial agents to this intracellular parasite. The intracellular penetration and excellent in vitro activity of fluoroquinolones make them attractive for treating intracellular infections such as brucellosis. Although antibacterial effect of fluoroquinolones against Gram-positive and Gram-negative bacteria has been investigated extensively (Paton and Reeves, 1988; Qadri and Johnson, 1989), little is known about the ability of fluoroquinolones to inhibit BruceUa. Gobernado et al. (1985) reported that ciprofloxacin and norfloxacin were active against B. melitensis
strains. Bosch et al. (1986) found similar results. To our knowledge, no one has tested the activity of lomefloxacin against B. melitensis. In this study we determined the in vitro effectiveness of lomefloxacin against B. melitensis. Concentrations as low as 0.03 p,g/ml inhibited 14 of the 114 isolates, and ~ 99% were susceptible at a concentration of 0.5 p,g/ml. Only one isolate was resistant to lomefloxacin with an MIC of > 5.0 ~g/ml. This isolate was initially fluoroquinolone-susceptible but developed resistance to ciprofloxacin while the patient was being treated with it. Bacterial resistance to fluoroquinolones has been observed previously in Staphylococcus aureus and in Gram-negative bacteria (Chapman et al., 1985; H u m p h r e y and Mulvihill, 1985) but not in Brucella. Generally, Brucella are not known for their ability to develop resistance to antimicrobial agents. Development of resistance to ciprofloxacin not only illustrates this potential but an MIC of > 5.0 }xg/ml for lomefloxacin emphasizes the occurrence of crossresistance among fluoroquinolones.
The authors thank Ms. Elizabeth Connor for literature search and Ms. Amy Pering for secretarial assistance.
REFERENCES Bosch J, Linares J, Lopez de Goicoencheh MJ, et al. (1986) In vitro activity of ciprofloxacin, ceftriaxone and five other antimicrobial agents against 95 strains of Brucella melitensis. J Antimicrob Chemother 17:459. Buchanan TM, et al. Brucellosis in the United States, 19601972. An abattoir-associated disease 2, II &III. Medicine 53:403-411, 1974. Chapman ST, Speller DCE, Reeves DS (1985) Resistance to ciprofloxacin. Lancet i:39. Chin N, Novelli A, Nue H (1988) In-vitro activity of lomefloxacin (CS-47111, NY-198), a difluoroquinolone 3carboxylic acid, compared with those of other quinolones. Antimicrob Agents Chemother 32:656. Farrell ID, Hinchutte PM, Robertson L. Sensitivity of Bru-
celia spp. to tetracycline and its analogues. J Clin Pathol 29:1097-1099, 1976.
Finch R, Martin J, Pilkington R (1988) In-vitro assessment of lomefloxacin (SC-47111)--A new quinolone derivative. J Antimicrob Chemother 22:881. Gobernado M, Canton E, Santos M (1985). In-vitro activity of ciprofloxacin and other 4-quinolones against Brucella melitensis. Proceeding of First International Ciprofloxacin Workshop, Leverkusen. p. 30. Hall WE, Marion RE (1970) In-vitro susceptibility of Brucelia to various antibiotics. Appl Microbiol 20:600. Hausler WJ, Mayer NP, Holcomb LA (1985) Brucella. In Manual of Clinical Microbiology. Eds. EM Lennette, A.
Note
Balows, WJ Hausler and HJ Shadomy. Washington, D.C.: American Society for Microbiology, p. 382-386. Humphrey H, Mulvihill E (1985) Ciprofloxacin resistant Staphylococcus aureus. Lancet ii:383. Paton JH, Reeves DS. Fluoroquinolone antibiotics: Microbiology, pharmacokinetics and clinicaluse. Drugs 36:193228, 1988. Qadri SMH, Johnson S (1989) Antibacterial activity of norfloxacin against bacterial isolates from the urinary tract. ] Nat Med Assoc 81:382. Rizzo-Naudi J, Griseti-Soler N, Canado W. Human bru-
279
cellosis: An evaluation of antibiotics in the treatment of brucellosis. Postgrad Med J 13:520-525, 1967. Schoenknecht FD, Sabath LD, Thornberry C (1985) Susceptibility tests: Special tests. In Manual of Clinical Microbiology. Eds. EM Lennette, A Balows, WJ Hausler and AJ Shadomy. Washington, D.C.: American Society for Microbiology, p. 1000-1008. Weinstein MP (1988) Comparative in-vitro activity of lomefloxacin and other antimicrobials against 597 microorganisms causing bacteremia. Diagn Microbiol Infect Dis 11:195.
DIAGN MICROBIOL INFECT DIS 1990;13:277-279
Antibacterial Activity of Lomefloxacin Against Brucella melitensis S.M. Hussain Qadri, Sultan A1-Sedairy, and Yoshio Ueno
The in vitro activity of Iomefloxacin was tested against 114 clinical isolates of Brucella melitensis. Comparison was made with ciprofloxacin, tetracycline, gentamicin, rifampin, and trimethoprim-sulfamethoxazole. Lomefloxacin inhibited 113 (99.1%) of the 114 strains tested at ~ 0.5 tzg/ml. It was corn-
parable to ciprofloxacin, tetracycline and gentamicin in antimicrobial potency. One strain that was previously susceptible to ciprofloxacin and had become resistant after the patient was treated with ciprofloxacin showed cross-resistance to lomefloxacin.
The newer preparations of fluoroquinolones have advanced the field of antimicrobial chemotherapy significantly. Their mode of action consists of inhibiting the supercoiling activity of the DNA gyrase, thus depressing the DNA and RNA synthesis and resulting in the killing of susceptible organisms (Paton and Reeves, 1988). Lomefloxacin is one of the new members of the fluorinated quinolones. It is a synthetic difluoroquinolone with a 3-piperazine moiety and is suitable for oral administration, with a half-life of - 8.5 hr. Its in vivo and in vitro effectiveness against a wide range of Gram-positive and Gram-negative bacilli, excluding Brucella, has been confirmed (Weinstein 1988; Finch et al., 1988; Chin et al., 1988). We believe that this is the first report on the susceptibility of Brucella melitensis to lomefloxacin. Other antimicrobials, such as ciprofloxacin, tetracycline, gentamicin, trimethoprim-sulfamethoxazole, and rifampin, were included for comparison. Clinical isolates from the blood, synovial fluid, mitral valve, or other tissues of 113 patients with B. melitensis infection were used and identified by standard methods (Hausler et al., 1985). Minimal inhib-
itory concentrations (MIC) were determined by broth dilution according to the method of Hall and Marion (1970), using Mueller-Hinton broth and an inoculum of 105 to 106 CFU/rrfl. The effect of antibacterial agents in combination was tested by the method of Schoenknecht et al., (1985). In all cases, incubation was at 36°C for 48 hr in a 5% CO2 incubator. The antibacterial activity of lomefloxacin, along with ciprofloxacin and four conventional agents against 114 clinical isolates of B. melitensis, is shown in Table 1. Of the 114 isolates tested, 113 were inhibited by ~ 0.5 ~g/ml of lomefloxacin, which was slightly more potent than ciprofloxacin. The parent strain of one of the resistant isolates with an MIC of > 5.0 ~g/ml to lomefloxacin and ciprofloxacin was originally susceptible to both drugs with an MIC of 0.06 ~g/ml. However, while the patient was being treated with ciprofloxacin, the organism developed resistance to ciprofloxacin and was cross-resistant to lomefloxacin. The isolate remained susceptible to tetracycline, gentamicin, rifampin, and trimethoprim-sulphamethoxazole. All of the isolates were inhibited by ~ 0.5 ~g/ml of both tetracycline and gentamicin. Trimethoprim-sulphamethoxazole and rifampin inhibited all of the isolates at a concentration of ~ 1.0 ~g/ml. Drug interaction studies (synergy) were performed using lomefloxacin in combination with conventional drugs. Lomefloxacin did not show any in vitro synergy with tetracycline, gentamicin, rifampin, or trimethoprim-sulphamethoxazole against these isolates. B. melitensis is a causative agent of brucellosis (un-
From the King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia Address reprint requests to: Dr. Syed M.H. Qadri, King Faisal Specialist Hospital and Research Centre, P. O. Box 3354, Riyadh 11211, Saudi Arabia. Received December 8, 1989; revised and accepted December 11, 1989. © 1990 Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0732-8893/90/$3.50
278
TABLE 1.
S.M. Hussain Qadri et al.
Susceptibility of 114 Clinical Isolates of B. melitensis to Lomefloxacin and Five Other Drugs MIC (~g/ml) (cumulative numbers)
Drug Lomefloxacin Ciprofloxacin Tetracycline Gentamicin Trimethoprimsulfamethoxazole ° Rifampin
0.03
0.06
0.12
0.25
0.5
1.0
14
26 21 13
54 42 51 6 8
101 97 92 103 47
113 113 114 114 84
114
8
65
90
114
aThe ratio of trimethoprim-sulfamethoxazolewas 1:19. dulant fever) that occurs primarily in goats and sheep. It was first identified in 1904 when it was isolated from the milk and urine of healthy goats. The infection is generally rare in man, with most of the cases resulting as an occupational hazard. However, it is endemic in most of the developing countries, including Saudi Arabia, mainly due to the consumption of uninspected meat and raw unpasteurized goat and sheep milk in the rural areas. This organism has remained susceptible to conventional antimicrobials. The relapse rate with different drugs has been reported to range between 5% and 70% (Buchanan et al., 1974; Farrell et al., 1976; Rizzo-Naudi et al., 1967). A probable explanation of these relapses may be relative inaccessibility of the antibacterial agents to this intracellular parasite. The intracellular penetration and excellent in vitro activity of fluoroquinolones make them attractive for treating intracellular infections such as brucellosis. Although antibacterial effect of fluoroquinolones against Gram-positive and Gram-negative bacteria has been investigated extensively (Paton and Reeves, 1988; Qadri and Johnson, 1989), little is known about the ability of fluoroquinolones to inhibit BruceUa. Gobernado et al. (1985) reported that ciprofloxacin and norfloxacin were active against B. melitensis
strains. Bosch et al. (1986) found similar results. To our knowledge, no one has tested the activity of lomefloxacin against B. melitensis. In this study we determined the in vitro effectiveness of lomefloxacin against B. melitensis. Concentrations as low as 0.03 p,g/ml inhibited 14 of the 114 isolates, and ~ 99% were susceptible at a concentration of 0.5 p,g/ml. Only one isolate was resistant to lomefloxacin with an MIC of > 5.0 ~g/ml. This isolate was initially fluoroquinolone-susceptible but developed resistance to ciprofloxacin while the patient was being treated with it. Bacterial resistance to fluoroquinolones has been observed previously in Staphylococcus aureus and in Gram-negative bacteria (Chapman et al., 1985; H u m p h r e y and Mulvihill, 1985) but not in Brucella. Generally, Brucella are not known for their ability to develop resistance to antimicrobial agents. Development of resistance to ciprofloxacin not only illustrates this potential but an MIC of > 5.0 }xg/ml for lomefloxacin emphasizes the occurrence of crossresistance among fluoroquinolones.
The authors thank Ms. Elizabeth Connor for literature search and Ms. Amy Pering for secretarial assistance.
REFERENCES Bosch J, Linares J, Lopez de Goicoencheh MJ, et al. (1986) In vitro activity of ciprofloxacin, ceftriaxone and five other antimicrobial agents against 95 strains of Brucella melitensis. J Antimicrob Chemother 17:459. Buchanan TM, et al. Brucellosis in the United States, 19601972. An abattoir-associated disease 2, II &III. Medicine 53:403-411, 1974. Chapman ST, Speller DCE, Reeves DS (1985) Resistance to ciprofloxacin. Lancet i:39. Chin N, Novelli A, Nue H (1988) In-vitro activity of lomefloxacin (CS-47111, NY-198), a difluoroquinolone 3carboxylic acid, compared with those of other quinolones. Antimicrob Agents Chemother 32:656. Farrell ID, Hinchutte PM, Robertson L. Sensitivity of Bru-
celia spp. to tetracycline and its analogues. J Clin Pathol 29:1097-1099, 1976.
Finch R, Martin J, Pilkington R (1988) In-vitro assessment of lomefloxacin (SC-47111)--A new quinolone derivative. J Antimicrob Chemother 22:881. Gobernado M, Canton E, Santos M (1985). In-vitro activity of ciprofloxacin and other 4-quinolones against Brucella melitensis. Proceeding of First International Ciprofloxacin Workshop, Leverkusen. p. 30. Hall WE, Marion RE (1970) In-vitro susceptibility of Brucelia to various antibiotics. Appl Microbiol 20:600. Hausler WJ, Mayer NP, Holcomb LA (1985) Brucella. In Manual of Clinical Microbiology. Eds. EM Lennette, A.
Note
Balows, WJ Hausler and HJ Shadomy. Washington, D.C.: American Society for Microbiology, p. 382-386. Humphrey H, Mulvihill E (1985) Ciprofloxacin resistant Staphylococcus aureus. Lancet ii:383. Paton JH, Reeves DS. Fluoroquinolone antibiotics: Microbiology, pharmacokinetics and clinicaluse. Drugs 36:193228, 1988. Qadri SMH, Johnson S (1989) Antibacterial activity of norfloxacin against bacterial isolates from the urinary tract. ] Nat Med Assoc 81:382. Rizzo-Naudi J, Griseti-Soler N, Canado W. Human bru-
279
cellosis: An evaluation of antibiotics in the treatment of brucellosis. Postgrad Med J 13:520-525, 1967. Schoenknecht FD, Sabath LD, Thornberry C (1985) Susceptibility tests: Special tests. In Manual of Clinical Microbiology. Eds. EM Lennette, A Balows, WJ Hausler and AJ Shadomy. Washington, D.C.: American Society for Microbiology, p. 1000-1008. Weinstein MP (1988) Comparative in-vitro activity of lomefloxacin and other antimicrobials against 597 microorganisms causing bacteremia. Diagn Microbiol Infect Dis 11:195.
