Amoxicillin 200

Rash may occur with administration of any penicillin.

Patients are over twice as likely to develop a rash while receiving ampicillin or amoxicillin (5-10%) versus the other penicillins (2%) (138). The ampicillin rash is maculopapular and is often self-limited. Patients who have infectious mononucleosis, cytomegalovirus infection, chronic lymphocytic leukemia, or are on concurrent allopurinol are at increased risk of development of such a rash. Neutropenia can occur with administration of any penicillin at an estimated incidence of 3-8%. Risk factors include high doses for a prolonged (> 10 day) period of time (166,В 176) and hepatic impairment (212).

The mechanism may be due to immune complex deposition on the neutrophil cell membranes (198). Patients should be monitored for this adverse effect if prolonged treatment courses are used.

Inhibition of platelet aggregation can occur due to alterations in adenosine diphosphate responses, particularly with ticarcillin and carbenicillin.

Prolonged bleeding times can result, along with actual bleeding (2,В 4,В 82,В 226).

Patients with thrombocytopenia and/or azotemia appear to be at increased risk. Increased bleeding times were seen in a study of 156 patients receiving ticarcillin (73%), piperacillin (43%), mezlocillin (25%), or cefotaxime (17%). Though some patients were receiving chemotherapy, which could confound results, the trend remained after those patients were removed from the analysis. Bleeding occurred in 34%, 17%, and 2% of patients receiving ticarcillin, piperacillin, and mezlocillin, respectively (82). This effect generally reverses upon drug discontinuation.

Increased doses and resultant serum concentrations of penicillin G have been associated with encephalopathy, particularly in patients with severe renal impairment (30).

Seizures can also be induced with elevated CSF concentrations of any penicillin (208).

Predisposing factors include renal impairment, a history of a seizure disorder, meningitis, or intraventricular antibiotic administration (15).

If neurologic symptoms develop, the dose of penicillin should be reduced or discontinued.

If seizures develop, benzodiazepines may be effective as treatment.

Hypokalemia has been reported with the penicillins (39), possibly due to effects on renal tubules and subsequent potassium loss.

This effect is more common with the carboxypenicillins.

Hyperkalemia can result from use of penicillin G potassium, and reports of death have occurred (

240

Patients with renal impairment should be monitored for potential electrolyte disturbances.

Hepatitis or cholestasis can occur with high dose oxacillin and is generally reversible upon drug discontinuation (38).

В Intravenous administration of penicillin G, nafcillin, oxacillin, and methicillin can cause thrombophlebitis.

Tissue necrosis can occur with extravasation of nafcillin.

If extravasation occurs, hyaluronidase can be used as a local antidote at the site of injury.

This reaction occurs in patients being treated with a penicillin (usually penicillin G) for a spirochetal infection (usually syphilis, but can include leptospirosis, Lyme disease, and others) and is a result of release of pyrogens from infecting organisms (268).

In patients with syphilis, the incidence is 50% in primary syphilis and rises to 75% in patients with secondary syphilis. The reaction usually begins within 2 hours of initiating syphilis treatment and it consists of fever, chills, sweating, tachycardia, hyperventilation, flushing, and myalgia. The duration is about 1 day and it can be treated with aspirin or prednisone (238).

When procaine penicillin G is used intramuscularly, 0.03 Вµg/mL for at least 7 days (114).

If serum concentrations fall to below the MIC for 18-24 hours, spirochetal regrowth will occur (74).

There is concern that BPG does not achieve adequate concentrations in the CSF to eradicateВ T. pallidum , therefore the CNS would not be treated appropriately (144,В 239).

It may be, however, that the treponemal burden is low early in the disease process in immunocompetent patients and treatment with BPG may be sufficient (114,В 271). Some clinicians may wish to use more aggressive therapy, however.

Patients with HIV infection and early syphilis mayВ fail treatmentВ with BPG and develop neurosyphilis (96) therefore these patients should be treated as if they had neurosyphilis, particularly in the later stages of HIV infection. In patients with neurosyphilis, failure of high-dose penicillin may occur (96). Infants with congenital syphilisВ may be treated with either intravenous penicillin G or PPG.

The data suggests, however that CSF concentrations achieved with intravenous penicillin G are significantly higher than that achieved with PPG (12), therefore intravenous penicillin G may be preferred.

Penicillins are commonly used are treatment forВ skinВ andВ soft tissue infections.

Impetigo is commonly caused by eitherВ group A streptococciВ or Staphylococcus aureus В and can occasionally result in acute glomerulonephritis.

BPG (1.2 mu in adults), penicillin VK, or amoxicillin have been used as treatment, but treatment failure may occur if the causative organism isВ Staphylococcus aureus В (62). Use of a penicillinase-resistant oral penicillin (e.g.

Bullous impetigo, usually caused byВ Staphylococcus aureus , may be treated with an oral penicillinase-resistant penicillin.

Staphylococcal scalded skin syndrome should be treated with an intravenous penicillinase-resistant penicillin. Erysipelas,commonly caused byВ group A streptococci, is a type of superficial cellulitis which may be treated successfully with oral penicillin VK (250-500mg q6h) (27). If the infection is more severe, intravenous penicillin G may be used.В CellulitisВ is a more extensive infection, which may be due to a number of different streptococci orВ Staphylococcus aureus . A penicillinase-resistant penicillin should be used empirically, either orally or intravenously, depending upon the severity of infection.

More severe skin infections, including necrotizing fasciitis, can be caused by group A streptococcus (streptococcal gangrene), along with other organisms, such as anaerobes and gram-negative rods.

In skin infections caused by streptococcus, aggressive therapy with penicillin G has been utilized yet is still associated with morbidity and mortality (27).

It is thought that the high organism inoculum seen in these infections is indicative of an increased number of organisms that are not actively replicating, against which penicillin is less effective (224).

There is experimental data to suggest that penicillin in combination with clindamycin may be more effective, since clindamycin’s mechanism of action is cell cycle independent (223,В 224).

Gas gangrene is a complication of a surgical or traumatic wound that can result in severe pain, skin discoloration, and edema.В Clostridium perfringens В and other Clostridial species are the common causative organisms. WhileВ surgical debridementВ is a cornerstone of therapy, antibiotic treatment is essential.

The drug of choice is penicillin G intravenously 10-24 mu daily in divided doses (57).

Decreased susceptibility ofВ Clostridium perfringens В has been seenВ in vitro В however (151), and some animal model studies have demonstrated poorer results in the penicillin treated animals versus animals that received other antibiotics such asВ metronidazoleВ or clindamycin (222).

The clinical significance of these findings is unclear, but some clinicians are using combinations of penicillin G and another agent for treatment of this serious

infection

Intravenous penicillin G (1MU q 4-6 hours) has been demonstrated to effectively result in negative cultures of previously positive blister fluid (196) and is considered the treatment of choice. Oral penicillin VK is often used in patients after receiving an animal bite, particularly a cat bite.

Antimicrobial prophylaxis is often indicated after such bites as the infection rate is high and is often caused byВ Pasteurella multocida В (143).

Penicillin VK’s coverage against this organism is good and a dosage of 250-500 mg every 6 hours for 10 days is often utilized. The oral flora of a cat or dog can also includeВ Staphylococcus aureus В and anaerobes; therefore some clinicians may choose amoxicillin/clavulanic acid to cover other possible organisms adequately.

Human oral flora includesВ Staphylococcus aureus ,В Eikenella corrodens , and anaerobes, therefore these bites should be treated with amoxicillin/clavulanic acid.

Other traumatic wounds may require antimicrobial prophylaxis, as well.

In a study of 599 patients with traumatic wounds of the hands or feet with underlying bone, tendon, or joint lesions, a penicillin G injection was compared with 6 days of oral penicillin VK or no treatment. Patients receiving intravenous penicillin G were significantly less likely to develop infection versus no treatment and patients receiving oral therapy had more gastrointestinal complaints.

A single dose of penicillin G may be a useful alternative as prophylaxis in these patients (146).

Treatment of acute pyelonephritis depends upon urine gram-stain and culture results.В AmoxicillinВ may be used for treatment ofВ enterococcalВ infection, but cephalosporins are probably a better choice for coverage ofВ Staphylococcus В (e.g.В Staphylococcus saprophyticus ).

In the past,В ampicillinВ and amoxicillin were drugs of choice for treatment of E.

coli В infection, however it is reported that 25-35% of isolates are now resistant (112). If use of a penicillin compound is desired, a combination beta-lactam/beta-lactamase inhibitor can be used (either orally or intravenously). Lower urinary tract infection can be treated with single dose therapy and amoxicillin 3g is a regimen that has been used (173), but because of increasing resistance, other agents may be more desirable.

Some experts suggest that with single dose or a 3-day course of therapy, the beta-lactams are inferior to other agents such asВ trimethoprim-sulfamethoxazoleВ at early and late follow-up (215). Penicillin G can be used as an adjunct to therapy for the treatment ofВ inhalational,В gastrointestinal, or oropharyngeal anthraxВ resulting from bioterrorism, however it should not be used as a sole agent (115). Data from an outbreak in late 2001 resulting from intentional anthrax infection noted that the isolates ofВ Bacillus anthracis were producers of constitutive and inducible beta-lactamases and non betalactamase stable penicillins, and are not likely to be clinically effective (46).

Penicillin G continues to be indicated for naturally occurring infections (10). Amoxicillin may also be used as an option for completion of therapy for cutaneous anthrax after treatment withВ ciprofloxacinВ orВ doxycyclineВ and after clinical improvement is documented (115).

Amoxicillin may be used for completion of a 60-day course of anthrax post exposure prophylaxis at a dosage of 500 mg three times daily in patients who have received a fluoroquinoloneВ or doxycycline for 14-21 days and if there are contraindications to use of those drugs, e.g. In infants and young children with sickle cell disease, oral penicillin VK is recommended as prophylaxis againstВ pneumococcal infectionВ at a dose of 125mg twice daily, starting before the child is 4 months of age. Oral penicillin VK is also recommended for children with functional or anatomical asplenia (7). Yaws, causedВ byВ Treponema pallidum , subspeciesВ pertenue В effects persons in tropical or subtropical areas and is characterized by skin and bone lesions.

Treatment of choice is a single dose of BPG 1.2 mu for individuals aged 10 or over and 600,000u for younger children.

Other treponemal diseases includeВ pinta, which manifests as unsightly skin lesions, and bejel, or endemic syphilis, which causes lesions of skin and bone and is not transmitted by sexual contact. BPG 1.2MU as a single dose is effective for both these

diseases

Mild disease can be treated with oral ampicillin (500-750mg q6h), amoxicillin (500mg q6h), or doxycycline (81). In moderate to severe disease, intravenous penicillin G (1.5mu q6h) has been shown to improve symptoms and shorten hospital stay (251). For prophylaxis, doxycycline, but not penicillin, is recommended (81).

Lyme disease, caused byВ Borrelia burgdorferi , is

treated

manifests