First-generation cephalosporin

It is possible to convert penicillin V or benzylpenieillin to a cephalosporin by chemical ring expansion. The first-generation cephalosporin cephalexin, for example, can be made in this way. Most cephalosporins used in clinical practice, however, are semisynthetics produced from the fermentation product cephalosporin C. 

Trimethoprim-sulfamethoxazole, amoxicillin, first-generation cephalosporins, and erythromycin are not recommended due to susceptibility and resistance patterns of the likely infectious organisms. 

As such, patients with penicillin allergies should be treated with a first-generation cephalosporin (if non-type I allergy), a macrolide/azalide, or clindamycin. Recurrent infections caused by reinfection, poor adherence to therapy, or true penicillin failure can be treated with amoxicillin-clavulanate, clindamycin, or penicillin G benzathine.45... 

The antibiotics of choice for treating methicillin-sensitive S. aureus (MSSA) infections are penicillinase-stable penicillins and first-generation cephalosporins. 

Because GAS historically has been the primary causative organism, penicillin has been the mainstay of therapy. O However, the incidence ofS. aureus impetigo is increasing, so oral penicillinase-stable penicillins or first-generation cephalosporins are now preferred.3 Erythromycin is an alternative choice when penicillin allergy is a concern. Topical mupirocin may be used alone when there are few lesions.3... 

In uncomplicated cases, prompt oral antibiotic therapy with amoxicillin or a first-generation cephalosporin halts the progression of lymphangitis. Clindamycin may be used if the patient has a significant (1-lactam allergy. Intravenous antibiotics (penicillinase-stable penicillins, first-generation cephalosporins,... 

Perforated peptic ulcer First-generation cephalosporins 1. Antianaerobic cephalosporins3 2. Possibly add aminoglycoside if patient condition is poor 3. Aminoglycoside with clindamycin or metronidazole add ampicillin if patient is immunocompromised or if biliary tract origin of infection... 

Liver As above but add a first-generation cephalosporin Use metronidazole if amoebic liver abscess is suspected... 

Spleen Aminoglycoside plus penicillinase-resistant penicillin Alternatives for penicillinase-resistant penicillin are first-generation cephalosporins or vancomycin... 

Acute First-generation cephalosporin Aminoglycoside plus ampicillin if severe infection... 

Pediatric6 100-200 mg/kg per day IV in divided doses every 4-6 hours First-generation cephalosporin ... 

Greater activity against gram-negative organisms than first-generation cephalosporins. 

BLIC, /5-lactamase inhibitor combination BL/BLI, jS-lactamase/jS-lactamase inhibitor FGC, first-generation cephalosporin MIC, minimal inhibitory concentration PRP, penicillinase-resistant penicillin SGC, second-generation cephalosporin TGC, third-generation cephalosporin. Penicillinase-resistant penicillin nafcillin or oxacillin. 

First-generation cephalosporins—IV cefazolin po cephalexin, cephradine, or cefadroxil. cSome penicillin-allergic patients may react to cephalosporins. 

If a patient has a mild, delayed allergy to penicillin, first-generation cephalosporins are effective alternatives but should be avoided in patients with an immediate-type hypersensitivity reaction. 

Staphylococcus penicillinase-resistant penicillin or first-generation cephalosporin... 

Perforated peptic First-generation cephalosporins ulcer... 

In patients allergic to penicillin, a macrolide such as erythromycin or a first-generation cephalosporin such as cephalexin (if the reaction is nonimmunoglobulin E-mediated hypersensitivity) can be used. Newer mac-rolides such as azithromycin and clarithromycin are as effective as erythromycin and cause fewer GI adverse effects. 

S. aureus accounts for the majority of infections consequently, a penicillin-resistant penicillin or first-generation cephalosporin is recommended. 

Serious infections should be treated intravenously with a penicillinase-resistant penicillin (nafcillin) or first-generation cephalosporin (cefazolin). Patients with penicillin allergies should be treated with vancomycin or clindamycin. 

Penicillinase-resistant penicillins, first-generation cephalosporins, macrolides, and clindamycin should not be used for treatment because of their poor activity against Pasteurella multocida. 

As streptococcal cellulitis is indistinguishable clinically from staphylococcal cellulitis, administration of a semisynthetic penicillin (nafrillin or oxacillin) or first-generation cephalosporin (cefazolin) is recommended until a definitive diagnosis, by skin or blood cultures, can be made (Table 47-4). If documented to be a mild cellulitis secondary to streptococci, oral penicillin VK, or intramuscular procaine penicillin may be administered. More severe streptococcal infections should be treated with IV antibiotics (such as ceftriaxone 50 to 100 mg/kg as a single dose). 

In penicillin-allergic patients, oral or parenteral clindamycin may be used. Alternatively, a first-generation cephalosporin such as cefazolin (1 to 2 g IV every 6 to 8 hours) may be used cautiously for patients who have not experienced immediate or anaphylactic penicillin reactions and are penicillin skin test negative. In severe cases in which cephalosporins cannot be used because of documented methicillin resistance or severe allergic reactions to /1-lactam antibiotics, IV vancomycin should be administered. 

Patients with noninfected bite injuries should be given prophylactic antibiotic therapy for 3 to 5 days. Amoxicillin-clavulanic acid (500 mg every 8 hours) is commonly recommended. Alternatives for penicillin-allergic patients include fluoroquinolones or trimethoprim-sulfamethoxazole in combination with clindamycin or metronidazole. First-generation cephalosporins, macrolides, clindamycin alone, or aminoglycosides are not recommended, as the sensitivity to E. corrodens is variable. 

First-generation cephalosporins (particularly cefazolin) are the preferred choice, particularly for clean surgical procedures. Antianaerobic cephalosporins (such as cefoxitin or cefotetan) are appropriate choices when broad-spectrum anaerobic and gram-negative coverage is desired. 

Thoracic surgery Vascular surgery S. aureus, S. epidermidis, Corynebaderium, enteric gram-negative bacilli Cefuroxime 750 mg IV every 8 hours x 48 hours First-generation cephalosporins are deemed inadequate and shorter durations of prophylaxis have not been adequately studied IA... 

In uncomplicated exacerbations, recommended therapy includes a mac-rolide (azithromycin, clarithromycin), second- or third-generation cephalosporin, or doxycycline. Trimethoprim-sulfamethoxazole should not be used because of increasing pneumococcal resistance. Amoxicillin and first-generation cephalosporins are not recommended because of /1-lactamase susceptibility. Erythromycin is not recommended because of insufficient activity against H. influenzae. 

Cefalexin is a first-generation cephalosporin and therefore an alternative preparation would be Zinnat tablets, which contains cefuroxime, a second-generation cephalosporin. A penicillin such as Augmentin, which contains co-amoxiclav, can be an appropriate alternative since it provides a very similar spectrum of activity. Klaricid contains clarithromycin, which is a macrolide. Utinor contains norfloxacin, which is a quinolone that is effective in uncomplicated urinary-tract infections. Rocephin contains ceftriaxone, which is a third-generation cephalosporin that is available for parenteral administration only. 

Patients allergic to penicillin may be cross-sensitive to cephalosporins. Cephalosporins (cefaclor, first-generation cephalosporin) are therefore avoided in these patients and instead macrolides (for example, erythromycin) are generally administered. Ketoconazole is an imidazole antifungal agent. 

First-generation cephalosporins, introduced into human medicine in the 1960 s and 1970 s, are basically similar in antibacterial activity and differ mainly in their pharmacokinetic properties. These include all of the currently available orally active cephalosporins, and are relatively susceptible to beta-lactamase, active against most Gram-positive bacteria and have a limited spectrum of activity against the Gram-negative organisms. 

First-generation cephalosporins (cefalotin, cefaloridin, cephalexin, cephapirin, cefa-zolin, cefadroxil, cephradine, and others) possess high biological activity with respect to staphylococci, streptococci, pneumococci, and many types of enterobacteria. 

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