Urinary pathogens, resistance

Norfloxacin (1, R = C2H5, R = H), a typical example, exhibits broad-spectrum activity and is useful in the treatment of upper respiratory tract and urinary infections [7] Lomefloxacin (2), a very recent introduction, is a third-generation product that, given once daily, is especially useful against pathogens resistant to cephalosponns, penicillins, and aminoglycosides [4] Floxacillin (J) is a stable, orally active antibacterial with improved activity over thenonfluonnated product (cloxacillin) [5]... 

The first-generation and oldest quinolones exhibit limited gram-negative activity. Nalidixic acid and cinoxacin do not achieve systemic antibacterial levels and are thus restricted to therapy of bladder infections caused by urinary pathogens, such as E. coli and Klebsiella and Proteus spp. Although they are bactericidal agents, their use is restricted by resistance. 

The cephalosporins and tetracyclines are commonly used for treatment of UTIs in other species. However, in horses, the cephalosporins are rarely more advantageous than the penicillins or potentiated sulfonamides. However, ceftiofur has broad-spectrum antimicrobial activity and may be indicated when urinary pathogens are resistant to... 

Chronic bacterial prostatitis occurs when acute bacterial prostatitis has been inadequately treated because of pathogen resistance, relapse, or short-course therapy or because of blocked drainage of secretions from the prostate. Most men with chronic prostatitis will have had a previous bout of acute prostatitis. The most common clinical feature of chronic prostatitis is recurrent urinary tract infections and the symptoms and complaints of acute bacterial prostatitis. Fluoroquinolones, trimethoprim-sulfamethoxazole, doxycycline, and nitrofurantoin are used in the management of chronic prostatitis. Chronic prostatitis warrants at least 10 to 12 weeks of therapy. Poor clinical outcomes, however, have been observed because of poor diffusion of antimicrobials into the prostate. 

Human microbial pathogens that possess the ability to adhere to host tissues have a distinct advantage over those that do not, in that they are better equipped to evade and resist the defense systems of their host. There are numerous adherence mechanisms that have been described to date. However, those that are most commonly studied originate from pafhogens that colonize the GIT and genital-urinary tract, including Salmonella, H. pylori, and pathogenic serotypes of E. coli. 

For infections frequently encountered outside hospitals, e.g. uncomplicated urinary tract infection in young women, surveillance of resistance data of the most likely pathogens Escherichia coli) allows physicians to prescribe empiric therapy without performing cultures in the individual patient. However, in severely ill hospitalised patients, it is necessary to take samples for culture before starting empiric therapy. Microscopy of the Gram stained smear can help fine-tune empiric therapy at an early stage. Whether the infection is community-acquired or hospital-acquired, and whether the patient has been exposed to previous antimicrobial therapy should also be taken into account when choosing empiric therapy. 

Acute uncomplicated urinary tract infections caused by E. coli and other pathogens generally respond promptly to one of the short-acting sulfonamides. Recurrent urinary tract infections (UTIs), when related to some structural abnormality in the tract, are frequently caused by sulfonamide-resistant bacteria. 

A combination of trimethoprim-sulfamethoxazole is effective treatment for a wide variety of infections including P jiroveci pneumonia, shigellosis, systemic salmonella infections, urinary tract infections, prostatitis, and some nontuberculous mycobacterial infections. It is active against most Staphylococcus aureus strains, both methicillin-susceptible and methicillin-resistant, and against respiratory tract pathogens such as the pneumococcus, Haemophilus sp, Moraxella catarrhalis, and Klebsiella pneumoniae (but not Mycoplasma pneumoniae). However, the increasing prevalence of strains of E coli (up to 30% or more) and pneumococci that are resistant to trimethoprim-sulfamethoxazole must be considered before using this combination for empirical therapy of upper urinary tract infections or pneumonia. 

Knowledge of the likely pathogens (and their current local susceptibility rates to antimicrobials) in the clinical situation. Thus cephalexin may be a reasonable first choice for lower urinary tract infection (coliform organisms — depending on the prevalence of resistance locally), and benzylpenicillin for meningitis in the adult (meningococcal or pneumococcal). 

Others. Leoofloxacin (t) 7h) has greater activity against Streptococcus pneumoniae than ciprofloxacin and is used for respiratory and urinary tract infection. Moxifloxacin (t) 12 h) has strong anti-Gram-positive activity, and may prove useful for respiratory tract infections including those caused by atypical pathogens and penicillin-resistant Streptococcus pneumoniae. 

Dornbusch K, Toivanen P. Effect of trimethoprim or trimethoprim/sulphamethoxazole usage on the emergence of trimethoprim resistance in urinary tract pathogens. Scand J Infect Dis 1981 13(3) 203-10. 

Uropathogenic E. coli cause 90% of the urinary tract infections. The bacteria colonize from the feces or perineal region and ascend the urinary tract to the bladder. With the aid of specific adhesins (pyelonephritis-associated pili) they are able to colonize the bladder. Another factor involved in the pathogenicity of the uropathogenic strains of E. coli is their resistance to complement-dependent bactericidal effect of serum. This phenomenon is associated with the presence of a capsule, which decrease the ability of antibodies and/or complement to bind to the bacterial surface, which in turn prevents the phagocytes from recognizing and engulfing the bacterial cells. 

Fosfomycin is excreted by the kidney, with urinary levels exceeding the minimal inhibitory concentrations (MiCs) for many urinaiy tract pathogens. In a single dose, the drug is less effective than a 7-day course of treatment with fluoroquinolones. With multiple dosing, resistance emerges rapidly and diarrhea is common. Fosfomycin may be synergistic with beta-lactam and quinolone antibiotics in specific infections. 

A. Nitrofurantoin This drug is active against many urinary tract pathogens (but not proteus or pseudomonas), and resistance emerges slowly. Single daily doses of the drug can prevent recur-... 

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