Antimicrobials combinations

In conclusion, rifaximin-based eradication regimens are promising but new antimicrobial combinations (with and without proton pump inhibitors) need to be explored in well-designed clinical trials including a large cohort of H. pylori-infected patients. 

Most infections should be treated with a single antimicrobial agent. Although indications for combination therapy exist, antimicrobial combinations are often overused in clinical practice. The unnecessary use of antimicrobial combinations increases toxicity and costs and may occasionally result in reduced efficacy due to antagonism of one drug by another. Antimicrobial combinations should be selected for one or more of the following reasons ... 

To obtain enhanced inhibition or killing. This use of antimicrobial combinations is discussed in the paragraphs that follow. 

Other synergistic antimicrobial combinations have been shown to be more effective than monotherapy with individual components. Trimethoprim-sulfamethoxazole has been successfully used for the treatment of bacterial infections and Pneumocystis jiroveci (carinii) pneumonia. 3-Lactamase inhibitors restore the activity of intrinsically active but hydrolyzable 3-lactams against organisms such as S aureus and Bacteroides fragilis. Three major mechanisms of antimicrobial synergism have been established ... 

The use of an antagonistic antimicrobial combination does not preclude other potential beneficial interactions. For example, rifampin may antagonize the action of anti-staphylococcal penicillins or vancomycin against staphylococci. However, the aforementioned antimicrobials may prevent the emergence of resistance to rifampin. 

Lambert, R.J.W., Hanlon, G.W. and Denyer, S.P. (2004) The synergistic effect of EDTA/antimicrobial combinations on Pseudomonas aeruginosa. J. Appl. Microbiol., 96, 244—253. 

To treat polymicrobial infections such as intra-abdominal abscesses. The antimicrobial combination chosen should cover the most common known or suspected pathogens but need not cover all possible pathogens. The availability of antimicrobials with excellent polymicrobial coverage (eg, 13-lactamase inhibitor combinations or imipenem) may reduce the need for combination therapy in the setting of polymicrobial infections. 

Fyfe, L., Armstrong, F. and Stewart, J. (1998) Inhibition of Listeria monocytogenes and Salmonella enteriditis by combinations of plant oils and derivatives of benzoic acid the development of synergistic antimicrobial combinations. International journal of Antimicrobial Agents 9(3), 1 95-1 99. 

Using antimicrobial combinations in appropriate circumstances, e.g. tuberculosis... 

Bacterial endocarditis. An aminoglycoside, usually gentamicin, should comprise part of the antimicrobial combination for enterococcal, streptococcal or staphylococcal infection of the heart valves, and for the therapy of clinical endocarditis which fails to yield a positive blood culture. 

Topical uses. Neomycin and framycetin, whilst too toxic for systemic use, are effective for topical treatment of infections of the conjunctiva or external ear. They are sometimes used in antimicrobial combinations selectively to decontaminate the bowel of patients who are to receive intense immunosuppressive therapy. Tobramycin is given by inhalation for therapy of infective exacerbations of cystic fibrosis. 

Lambert RJW, Johnston MD, Hanlon GW, Denyer SP. Theory of antimicrobial combinations biocide mixtures—synergy or additions J Appl Microbiol 2003 94 747—759. 

Although not performed routinely during the clinical man- agement of patients with infections, data from certain laboratory tests (e.g., minimal bactericidal concentration tests, timed-kill tests, post-antibiotic-effect tests, and antimicrobial combination testing) are important for the clinician to understand because they help to determine an antimicrobial s pharmacodynamic properties. 

Antimicrobial combination therapy is used frequently to treat serious infections. Combination therapy may be used prior to knowing the pathogen or antibiotic susceptibility for the treatment of infections in neutropenic patients and in patients with enterococcal endocarditis or bacteremia, sepsis, or pneumonia caused by P. aeruginosa. In these cases, it is important to know whether the combination will have beneficial (or detrimental) effects on the overall antibacterial activity of the regimen. For example, the combination may result in activity that is... 

Elipoulos G, Moellering RC Jr. Antimicrobial combinations. In Lorian V ed. Antibiotics in Laboratory Medicine, 4th ed. Baltimore, Williams Wilkins, 1996 330-397. 

The addition of clavulanic acid (below) to amoxicillin (Augmentin) gives a combination in which the clavulanic acid serves to protect amoxicillin to a considerable extent against (3-lactamases. This is now an extremely popular antimicrobial combination for outpatient use. 

Personal Amyloglucosidase Antimicrobial (combined with glucose... 

TEM groups. Tazobactam is beta-lactamase inhibitor that helps piperacillin work better. Recently, its combination with ceftolozane and metronidazole was found to be a safe and effective new antimicrobial combination approved for the treatment of complicated gastrointestinal and urinary-tract infection [129]. 

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