Methicillin-resistant strains of Staphylococcus aureus resistant to quinolones

Schaefler, S.

doi:10.1128/jcm.27.2.335-336.1989

Cited by 111 publications

(13 citation statements)

References 6 publications

(6 reference statements)

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“…This is in contrast to reports of staphylococcal infections in humans. in which substantial resistance to ciprofloxacin has been observed in multi-resistant staphylococcus strains, particularly S. aureus (Raviglione et a/.. 1990;Schaefler. 1989;Shalit et al.…”

Section: Discussionmentioning

confidence: 99%

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In vitro activity of fifteen antimicrobial agents against methicillin‐resistant and methicillin‐susceptible Staphylococcus intermedius

Píriz

Valle

Mateos

et al. 1996

Vet Pharm & Therapeutics

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In this study the susceptibility of 91 methicillin-resistant and -susceptible Staphylococcus intermedius strains (MRSI and MSSI, respectively) against 15 antimicrobial agents was determined. The activity of the antimicrobial agents was studied at pH 7.2 and pH 8.5. Methicillin was more active at pH 7.2 (28 strains methicillin-resistant) than at pH 8.5 (55 strains methicillin-resistant). Gentamicin showed excellent activity, with only 3 strains resistant at pH 8.5. However, gentamicin would have to be administered parenterally. Oxytetracycline cannot be recommended for treatment of canine staphylococcal dermatitis, due to the high percentage (over 25%) of strains that were found to be resistant. Clindamycin showed little activity in inhibiting growth of the strains studied, the percent resistance at pH 7.2 was 93.4%. Rifampin behaved differently at the two pH values. However, a close relationship was noted between methicillin-resistant and rifampin-resistant strains, particularly at the lower pH. Of the fluoroquinolones, ciprofloxacin or enrofloxacin would be a good useful alternative for the treatment of methicillin-resistant strains of S. intermedius. Lastly, very high resistance to sulphamethoxypyridazine was found, as was the case with trimethoprim and a combination of trimethoprim/sulphamethoxypyridazine, against not only MRSI but also MSSI strains.

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Section: Discussionmentioning

confidence: 99%

“…afforded the possibility of effective treatment for infections produced by MRSA strains. Unfortunately, recent studies have reported an alarming increase in resistance to ciprofloxacin in multi-resistant strains, especially in the case of S. aureus (Shalit et al, 1989: Schaefler, 1989Raviglione et a!.. 1990).…”

Section: Introductionmentioning

confidence: 99%

In vitro activity of fifteen antimicrobial agents against methicillin‐resistant and methicillin‐susceptible Staphylococcus intermedius

Píriz

Valle

Mateos

et al. 1996

Vet Pharm & Therapeutics

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“…As fluoroquinolones have been used increasingly, some bacteria, especially methicillin-resistant S. aureus and Pseudomonas aeruginosa, have developed resistance to them (3,31,32). In S. aureus, four quinolone resistance mechanisms have been reported: (i) point mutation in the gyrA and gyrB genes is related to quinolone resistance (9,12,16); (ii) a membrane protein, NorA, contributes to active efflux-mediated resistance; (iii) cfxB-ofxC (flqA) confers quinolone resistance in S. aureus, although its mechanism is still unknown (35); and (iv) point mutations in the grlA gene are also responsible for quinolone resistance (10).…”

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confidence: 99%

Hydrophilicity of quinolones is not an exclusive factor for decreased activity in efflux-mediated resistant mutants of Staphylococcus aureus

Takenouchi¹,

Tabata²,

Iwata³

et al. 1996

Antimicrob Agents Chemother

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The elevated expression of the norA gene is responsible for efflux-mediated resistance to quinolones in Staphylococcus aureus (E.Y.W. Ng, M. Trucksis, and D.C. Hooper, Antimicrob. Agents Chemother. 38:1345-1355, 1994). For S. aureus transformed with a plasmid containing the cloned norA gene, SA113(pTUS20) (H. Yoshida, M. Bogaki, S. Nakamura, K. Ubukata, and M. Konno, J. Bacteriol. 172:6942-6949, 1990), and an overexpressed mutant, SA-1199B (G.W. Kaatz, S.M. Seo, and C.A. Ruble, J. Infect. Dis. 163:1080-1086, 1991), the MICs of norfloxacin increased 16 and 64 times compared with its MICs for the recipient and wild-type strains, SA113 and SA-1199, respectively. MICs of CS-940, however, increased only two and eight times, even though these two fluoroquinolones are similarly hydrophilic (apparent logPs of approximately -1). No good correlation was found, among 15 developed and developing quinolones, between the increment ratio in MICs and hydrophobicity (r = 0.61). Analysis of the quantitative structure-activity relationship among 40 fluoroquinolones revealed that the MIC increment ratio was significantly correlated with the bulkiness of the C-7 substituent and bulkiness and hydrophobicity of the C-8 substituent of fluoroquinolones (r = 0.87) and not with its molecular hydrophobicity (r = 0.47). Cellular accumulation of norfloxacin in SA-1199B was significantly lower than that in SA-1199, and it was increased by addition of carbonyl cyanide m-chlorophenyl hydrazone. On the other hand, accumulations of CS-940 in these strains were nearly identical, and they were not affected by addition of the protonophore.

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“…Resistance among strains of Pseudomonas aeruginosa has increased in Germany since the introduction of norfloxacin and ofIoxacin,l5 and the prevalence of quinolone-resistant strains of methicillin-resistant Staphylococcus aureus has increased to high levels in some institutions since the introduction of ciprofloxacin. [16][17][18][19][20][21] Significant reservoirs of such isolates include Veterans Administration and longterm care facilities. In Japan, resistance is increasing in other gram-negative bacteria such as Serratia marcescens.22…”

Section: Mechanisms Of Action and Resistancementioning

confidence: 99%

The Role of the Fluoroquinolones

Guay

1992

Pharmacotherapy

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Over the past decade, the quinolone antimicrobial class has enjoyed a renaissance with the emergence of the fluoroquinolone subclass. Norfloxacin, ciprofloxacin, ofloxacin, enoxacin, and lomefloxacin have the advantages of broad antimicrobial activity profiles including gram‐positive and ‐negative aerobes, favorable pharmacokinetic profiles including substantial oral bioavailability and extensive tissue distribution, and in general, favorable safety profiles. As clinical experience accumulates, our understanding of their optimum roles will become more refined. In six instances, these agents may be preferred over currently available agents: complicated urinary tract infections, empiric therapy of suspected bacterial gastroenteritis, eradication of the Salmonella carrier state, respiratory exacerbations due to Pseudomonas aeruginosa in patients with cystic fibrosis, invasive external otitis, and chronic gram‐negative bacillary osteomyelitis. The efficacy and convenience of these agents for the treatment of a broad range of infections have already resulted in their extensive use. Such use carries the risk of selection pressure for the development of resistance and the adverse consequences of increased cost over less expensive, equally effective alternatives. The use of the fluoroquinolones should focus on infections where there is demonstrated benefit of these agents over conventional agents or infections for which there are few or no alternatives.

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Methicillin-resistant strains of Staphylococcus aureus resistant to quinolones

Cited by 111 publications

References 6 publications

In vitro activity of fifteen antimicrobial agents against methicillin‐resistant and methicillin‐susceptible Staphylococcus intermedius

In vitro activity of fifteen antimicrobial agents against methicillin‐resistant and methicillin‐susceptible Staphylococcus intermedius

Hydrophilicity of quinolones is not an exclusive factor for decreased activity in efflux-mediated resistant mutants of Staphylococcus aureus

The Role of the Fluoroquinolones

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