eMedicine Specialties > Infectious Diseases > Bacterial Infections

Pasteurella Multocida Infection

Alexandre Lacasse, MD, MSc, Fellow in Infectious Diseases, University of Tennessee at Memphis
Michael Gelfand, MD, FACP, Chief, Professor, Department of Internal Medicine, Division of Infectious Diseases, Methodist Healthcare of Memphis, University of Tennessee; Thomas Lafeber, MD, Consulting Staff, Wellstar Infectious Disease LLC; J Robert Cantey, MD, Chief of Infectious Disease, Veterans Affairs Medical Center, Director, Professor, Department of Medicine, Division of Infectious Diseases, Medical University of South Carolina

Updated: Jan 21, 2009

Introduction

Background

Pasteurella multocida is a small, gram-negative, nonmotile, non–spore-forming coccobacillus with bipolar staining features. P multocida often exists as a commensal in the upper respiratory tracts of many livestock, poultry, and domestic pet species, especially cats and dogs. P multocida infection in humans is often associated with an animal bite, scratch, or lick, but infection without epidemiologic evidence of animal contact may occur.

Wound infections associated with animal bites usually have a polymicrobial etiology, mandating the empiric use of broad-spectrum antimicrobials targeted at both aerobic and anaerobic gram-negative bacteria. Nevertheless, Pasteurella species are commonly isolated pathogens in most animal bites, especially in dog- and cat-related injuries. These injuries can be aggressive, with skin manifestations typically appearing within 24 hours following a bite. These wounds can exhibit a rapidly progressive soft-tissue inflammation that may resemble group A β-hemolytic Streptococcus pyogenes infections.

Deeper soft tissue can also be affected, manifesting as tenosynovitis, septic arthritis, and osteomyelitis. More-severe disseminating infections may also develop, including endocarditis or meningitis, the latter mimicking Haemophilus influenzae or Neisseria meningitides infections in young children. Fortunately, Pasteurella species are fairly sensitive organisms and can be treated with a penicillin-based regimen.

Pathophysiology

• Local: P multocida infection usually presents as an infection that complicates an animal bite or injury. Complications include rapidly progressive cellulitis, abscesses, tenosynovitis, osteomyelitis, and septic arthritis. The latter two are particularly common following cat bites because of their small, sharp, penetrative teeth.
• Respiratory: P multocida may cause upper respiratory tract infections, including sinusitis, otitis media, mastoiditis, epiglottitis, pharyngitis, and Ludwig angina.^{[1 ]}In rare cases, P multocida may also cause lower respiratory tract infections, including pneumonia, tracheobronchitis, lung abscess,^{[2 ]}and empyema,^{[3 ]}usually in individuals with underlying pulmonary disease.
• Cardiovascular: P multocida has been reported to cause native- and prosthetic-valve endocarditis,^{[4 ]}pericarditis, mycotic aneurysms, vascular graft infections, central venous catheter infections, bacteremia, sepsis, and septic shock.
• Central nervous system: P multocida is an uncommon cause of meningitis, subdural empyema, and brain abscess. P multocida meningitis has been associated with cat licks and bites occurring on the face in persons at the extremes of age.^{[5 ]}
• Gastrointestinal: P multocida rarely causes gastrointestinal problems but has been associated with appendicitis, hepatosplenic abscesses, and spontaneous bacterial peritonitis. P multocida has been isolated in patients with polymicrobial peritoneal dialysis catheter–associated peritonitis.
• Ocular: P multocida periocular abscess, conjunctivitis, corneal ulcers, and endophthalmitis have been reported.
• Genitourinary tract: P multocida pyelonephritis, renal abscess, epididymitis, and cervicitis have been reported in rare cases.

Frequency

United States

According to the American Pet Association, approximately 150 million dogs and cats live in the United States, cats currently outnumbering dogs by 13 million. Animal bites account for 1% of annual emergency department visits. The estimated cost in health care expenditures has been reported to be $30 million per year. Approximately 10% of animal bites require medical attention; 1-2% eventually require hospitalization.

The vast majority of animal bites involve dogs (85-90%), followed by cats (5-10%). Infectious complications occur in approximately 15-20% of dog-related bites and more than 50% of cat-related ones. Dog bites are associated with younger animals engaging in playful activities, mostly with children. German shepherd, pit bull, Staffordshire terrier, and mixed breeds are most commonly involved with human bites, while the golden retriever and Labrador retriever are least. Cat bites are usually provoked, typically by female felines, and occurring on the upper extremities or face. Sharp and long teeth of cats can easily penetrate human skin and create a deep puncture wound and even inoculate the periosteum component of bones. Indeed, cat-related wounds more commonly progress to more serious and deeper-tissue infections, including osteomyelitis and meningitis.

International

P multocida infections occur worldwide. Cats are involved in 60-80% of human P multocida infections. Moreover, P multocida is isolated in 50% of dog bites.

Mortality/Morbidity

It is estimated that 10-20 human deaths per year occur following an animal bite.

Infectious complications occur in approximately 15-20% of dog-related bites and more than 50% of cat-related ones. Following a bite, a rapidly progressive cellulitis may develop; deeper structures, including tendons, joints, and bones, can become affected, especially in cat-related injuries. Dissemination can occur.

Degenerative joint disease, rheumatoid arthritis, and prosthetic joints have been associated with the development of P multocida septic arthritis.

Chronic obstructive pulmonary disease is a risk factor for P multocida respiratory tract infection, which carries a mortality rate of approximately 30%. Diabetes mellitus and liver dysfunction are predisposing conditions associated with pasteurellosis and associated bacteremia.^{[6 ]}

P multocida infections during pregnancy and in utero transmission have also been reported.^{[7,8 ]}

Localized P multocida infections carry an excellent prognosis. Significant morbidity has been associated with musculoskeletal P multocida infections, especially those involving the hand. Disseminated P multocida infections carry a 25-30% overall mortality risk.

Age

All age groups can be affected by P multocida infections. Young children seem to be frequently involved in nonfatal dog bites. P multocida meningitis typically occurs in persons at the extremes of age.

Clinical

History

• A history of animal exposure, whether occupational or recreational, should alert the physician to the possibility of a zoonosis.
• A detailed pet history, including exposure to pets owned by friends or strangers, should reveal the possibility of Pasteurella infection. However, cases of Pasteurella infection occur in the total absence of an epidemiological link.

Physical

Physical findings of P multocida infection relate to the site of infection, as follows:

• Local - Erythema, warmth, pain and tenderness, purulent discharge, lymphangitis, joint swelling, decreased range of motion
• Respiratory - Sinus tenderness, hoarseness, pharyngeal erythema, rales and rhonchi upon chest auscultation, dullness to percussion, changes in vocal fremitus
• CNS - Focal neurologic deficits, signs of meningeal irritation (eg, nuchal rigidity, Brudzinski sign, Kernig sign)
• Abdominal - Abdominal tenderness, guarding and rebound, hepatosplenomegaly, costovertebral angle tenderness
• Ocular - Corneal ulcer, conjunctival injection, decreased visual acuity
• Cardiovascular - Hypotension, tachycardia, new cardiac murmur, embolic phenomenon
• Lymph nodes - Regional adenopathy

Causes

Causes of P multocida infection include the following:

• Dog bite or lick
• Cat bite, lick, or scratch
• Idiopathic (no history of pet exposure)
• Immunosuppression

Differential Diagnoses

Other Problems to Be Considered

Infective endocarditis
Osteomyelitis
Septic arthritis
Necrotizing fasciitis
Tenosynovitis
Catheter-associated bloodstream infections
Spontaneous bacterial peritonitis
Peritoneal dialysis catheter-associated peritonitis

Workup

Laboratory Studies

• Gram stain of purulent material or other fluid specimens including blood, sputum, and cerebrospinal fluid may show small, gram-negative, nonmotile, non–spore-forming pleomorphic coccobacilli.
• Haemophilus species, N meningitides, Moraxella species, and Acinetobacter species have a morphology that is similar to that of P multocida infection and can therefore be easily confused with Pasteurella species .
• Wright, Giemsa, and Wayson stains enhance bipolar staining. Some P multocida strains exhibit a mucous capsule.
• Pasteurella species are highly sensitive to several penicillins and cephalosporins. Susceptibility testing is indicated in immunocompromised patients and in the setting of treatment failure or drug allergies.

Imaging Studies

• CT scanning and/or MRI: Evaluation of tenosynovitis, septic arthritis, osteomyelitis, and meningeal enhancement, when appropriate
• Echocardiography: Evaluation of suspected endocarditis

Procedures

• Deep soft-tissue P multocida infections require debridement at times. Intraoperative cultures should be taken at time of surgery.
• Lumbar puncture should be performed if meningitis is suspected.
• Arthrocentesis should be performed if septic arthritis is suspected.
• Abdominal paracentesis is required in patients with ascites to assess the possibility of spontaneous bacterial peritonitis, especially in those with significant clinical liver disease with a history of pet exposure.

Histologic Findings

• When available, infected tissue has features consistent with an acute purulent inflammation with neutrophilic predominance and possibly necrosis.

Treatment

Medical Care

• Because P multocida infection is mostly encountered in the setting of an injury following an animal bite, physicians must be familiar with the associated microbiological oral flora of certain animals, especially dogs and cats.
• Most animal bites are polymicrobial, with both aerobic and anaerobic bacteria. Several species can be isolated at once.
• Several Pasteurella species are associated with dog and cat bites, including P multocida subspecies multocida, P multocida subspecies septica, Pasteurella stomatis, and Pasteurella dogmatis. Pasteurella canis is associated only with dog bites.
• Other fastidious gram-negative organisms that have been associated with dog and cat bites include Capnocytophaga canimorsus and Capnocytophaga cynodegmi, especially in patients who had undergone previous splenectomy. C canimorsus infection can cause fulminant sepsis and meningitis, whereas C cynodegmi infection usually causes a milder localized inflammation.
• Several other organisms are associated with cat bites, including Bartonella henselae , Francisella tularensis, and cowpox virus.
• Medical management of animal bite wounds includes local wound care, standard-protocol tetanus prophylaxis, standard-protocol rabies prophylaxis, and either oral or intravenous empiric antimicrobial treatment.
• Antimicrobial treatment is discussed in Medication.
• Local care of bite wounds includes cleansing and removing nonviable tissue.
  • Gently cleanse the skin surrounding the bite wound with an antiseptic solution. To prevent further tissue injury, do not scrub the wound directly.
  • Soaking is of no benefit, but copious irrigation with a small-gauge catheter on a syringe helps remove debris and decreases the concentration of bacteria in contaminated wounds. Debridement and closure are discussed in Surgical Care.

Surgical Care

The initial assessment of an animal bite includes an estimation of the infection risk. Bites to the head and neck, to the distal extremities, and near joints carry the highest risk of infection. In general, persons with animals bite wounds are at a high risk for infection, especially those who present to medical attention more than 8-10 hours after the injury occurred.

Persons with underlying medical diseases, such as diabetes mellitus, chronic liver disease, asplenia, alcoholism, HIV infection, or other immunodeficiency conditions (including chronic steroid exposure), are at increased risk of infection.

• After irrigation and cleansing, sharply débride nonviable tissue to reduce the risk of infection and to allow easier suturing by providing a more even edge.
• Primary suturing of bite wounds is reserved for minor injuries, those at low risk for infection, and those that have been treated within 8-10 hours of injury.
• Leave all other wounds open until the risk of infection is reduced by cleansing, debridement, and prophylactic antibiotics.

Consultations

• General surgeon
• Orthopedic surgeon

Activity

• Elevation is of great importance in the management of limb injuries. Lack of elevation may result in excessive edema, which may produce compartment syndrome and compromise local circulation, to the extent of threatening the viability of the limb.
• Wounds on extremities should be immobilized and elevated with a sling to reduce edema, which may hamper normal activities.

Medication

Antimicrobial resistance among Pasteurella isolates is rarely reported in humans. Tetracyclines, erythromycin, and penicillin are most commonly associated with resistance. Penicillin-resistant strains have been isolated only from respiratory tract infections. Most animal-bite injuries can be treated with oral antimicrobials on an outpatient basis. Severe or partially responding infections may necessitate hospitalization and parenteral antimicrobial administration, along with surgical intervention.

Most Pasteurella isolates are susceptible to oral antimicrobials such as amoxicillin, amoxicillin/clavulanic acid, minocycline, fluoroquinolones (ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin), and trimethoprim-sulfamethoxazole. Based on in vitro susceptibility data, several antimicrobials should not be used empirically for P multocida infections, including dicloxacillin, vancomycin, cephalexin, cefaclor, cefadroxil, erythromycin, and clindamycin. Macrolide resistance is usually encountered with erythromycin. Other macrolides, including azithromycin, clarithromycin, and telithromycin (in order of decreasing susceptibility), retain in vitro activity against most Pasteurella strains. Aminoglycosides have poor activity against P multocida.

More-severe infections may require parenteral antibiotics. Intravenous ampicillin-sulbactam, ticarcillin-clavulanate, piperacillin-tazobactam, cefoxitin, and carbapenems (imipenem-cilastatin, meropenem, ertapenem) are excellent empiric options for animal-bite injuries, providing gram-positive, gram-negative, and anaerobic coverage. The new tetracycline-derivative tigecycline also has excellent in vitro activity against P multocida and other pathogens encountered in animal and bite injuries. If P multocida is the only isolated organism, therapy may be changed to intravenous penicillin G. Once clinical improvement is noted, oral penicillin VK is an option. Patients with penicillin allergies can receive minocycline, doxycycline, fluoroquinolones, trimethoprim-sulfamethoxazole, or azithromycin.

The duration of therapy for P multocida infections has not been well established and can be tailored to clinical response. Milder soft-tissue infections usually require 7-10 days of oral therapy. More-severe cases can be treated for 10-14 days. Deep-tissue infections often require 4-6 weeks of therapy, usually intravenously at first.

Antibiotics

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Amoxicillin and clavulanate (Augmentin)

Drug combination treats bacteria resistant to beta-lactam antibiotics. For children >3 mo, base dosing protocol on amoxicillin content. Because of different ratios of amoxicillin to clavulanic acid in 250-mg tab (250:125) vs 250-mg chewable tab (250:62.5), do not use 250-mg tab until child weighs >40 kg.

Dosing

Adult

500-875 mg PO q12h or 250-500 mg PO q8h

Pediatric

<40 kg: 20-40 mg/kg/d PO divided bid
>40 kg: Administer as in adults

Interactions

Coadministration with warfarin or heparin increases risk of bleeding

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adjust dose in renal impairment; may increase risk of candidiasis

Cefuroxime (Ceftin, Zinacef)

Second-generation cephalosporin that maintains gram-positive activity of first-generation cephalosporins; adds activity against Proteus mirabilis, H influenzae, Escherichia coli, Klebsiella pneumoniae, and Moraxella catarrhalis. Condition of patient, severity of infection, and susceptibility of microorganism determine proper dose and route of administration.

Dosing

Adult

500 mg PO bid; alternatively, 750-1500 mg IV/IM q8h; not to exceed 6 g/d

Pediatric

Children: 250 mg PO bid
Adolescents: Administer as in adults

Interactions

Disulfiramlike reactions may occur when alcohol is consumed within 72 h after administration; may increase hypoprothrombinemic effects of anticoagulants; may increase nephrotoxicity in patients receiving potent diuretics (eg, loop diuretics); coadministration with aminoglycosides increase nephrotoxic potential

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Reduce dosage by half if CrCl is 10-30 mL/min and by three quarters if <10 mL/min (high doses may cause CNS toxicity); bacterial or fungal overgrowth of nonsusceptible organisms may occur with prolonged or repeated therapy

Doxycycline (Vibra-Tabs, Bio-Tab, Doryx, Vibramycin)

Inhibits protein synthesis and, thus, bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria.

Dosing

Adult

200 mg PO/IV immediately, followed by 100-200 mg PO q12h

Pediatric

<8 years: Not recommended
>8 years: 2-5 mg/kg/d PO/IV qd or divided bid; not to exceed 200 mg/d

Interactions

Bioavailability decreases with antacids containing aluminum, calcium, magnesium, iron, or bismuth subsalicylate; tetracyclines can increase hypoprothrombinemic effects of anticoagulants; tetracyclines can decrease effects of oral contraceptives, causing breakthrough bleeding and increased risk of pregnancy

Contraindications

Documented hypersensitivity; severe hepatic dysfunction

Precautions

Pregnancy

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Photosensitivity may occur with prolonged exposure to sunlight or tanning equipment; reduce dose in renal impairment; consider drug serum level determinations in prolonged therapy; tetracycline use during tooth development (last half of pregnancy through 8 y) can cause permanent discoloration of teeth; Fanconilike syndrome may occur with outdated tetracyclines

Penicillin G (Pfizerpen)

Inhibits biosynthesis of cell wall mucopeptide. Bactericidal against sensitive organisms when adequate concentrations are reached. Most effective during the stage of active multiplication. Inadequate concentrations may produce only bacteriostatic effects. Use penicillin VK for PO or penicillin G for IV.

Dosing

Adult

Penicillin VK 250-500 mg PO q6h or penicillin G sodium aqueous 2-4 million U IV q4h (not to exceed 24 million U/d)

Pediatric

50,000 U/kg IM; not to exceed 2.4 million U

Interactions

Probenecid may increase effectiveness by decreasing clearance; tetracyclines are bacteriostatic, causing a decrease in the effectiveness of penicillins when administered concurrently

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in renal impairment

Ampicillin and sulbactam (Unasyn)

Drug combination of beta-lactamase inhibitor with ampicillin. Covers skin, enteric flora, and anaerobes. Not ideal for nosocomial pathogens.

Dosing

Adult

1.5 (1 g ampicillin + 0.5 g sulbactam) to 3 g (2 g ampicillin + 1 g sulbactam) IV/IM q6h; not to exceed 4 g/d sulbactam or 8 g/d ampicillin

Pediatric

3 months to 12 years: 100-200 mg ampicillin/kg/d (150-300 mg Unasyn) IV divided q6h
>12 years: Administer as in adults; not to exceed 4 g/d sulbactam or 8 g/d ampicillin

Interactions

Probenecid and disulfiram elevate ampicillin levels; allopurinol decreases ampicillin effects and has additive effects on ampicillin rash; may decrease effects of oral contraceptives

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adjust dose in renal failure; evaluate rash and differentiate from hypersensitivity reaction

Ticarcillin and clavulanate (Timentin)

Inhibits biosynthesis of cell wall mucopeptide and is effective during stage of active growth. Antipseudomonal penicillin plus beta-lactamase inhibitor that provides coverage against most gram-positive organisms, most gram-negative organisms, and most anaerobes.

Dosing

Adult

3.1 g (3 g ticarcillin and 0.1 g clavulanate) IV q6h

Pediatric

75 mg/kg IV q6h

Interactions

Tetracyclines may decrease effects of ticarcillin; high concentrations of ticarcillin may physically inactivate aminoglycosides if administered in same IV line; effects are synergistic when administered concurrently with aminoglycosides; probenecid may increase penicillin levels

Contraindications

Documented hypersensitivity; severe pneumonia, bacteremia, pericarditis, emphysema, meningitis, and purulent or septic arthritis should not be treated with oral penicillin during acute stage

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Perform CBC count prior to initiation of therapy and at least weekly during therapy; monitor for liver function abnormalities by measuring AST and ALT during therapy; exercise caution in patients with hepatic insufficiencies; perform urinalysis and BUN and creatinine determinations during therapy and adjust dose if values become elevated; monitor blood levels to avoid possible neurotoxic reactions

Ciprofloxacin (Cipro)

Mode of action of all quinolones involves inhibition of bacterial DNA synthesis by blocking the enzyme DNA gyrase

Dosing

Adult

250-500 mg PO bid

Pediatric

<18 years: Not recommended
>18 years: Administer as in adults

Interactions

Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism of fluoroquinolones; reduces therapeutic effects of phenytoin; probenecid may increase serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy

Amoxicillin (Trimox, Amoxil)

Interferes with synthesis of cell wall mucopeptides during active multiplication, resulting in bactericidal activity against susceptible bacteria.

Dosing

Adult

1 g PO q8h; not to exceed 3 g/d

Pediatric

20-50 mg/kg/d PO divided q8h; not to exceed 2 g/dose

Interactions

Reduces efficacy of oral contraceptives

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adjust dose in renal impairment; may increase risk of candidiasis

Levofloxacin (Levaquin)

For pseudomonal infections and infections due to multidrug-resistant gram-negative organisms.

Dosing

Adult

500-750 mg PO qd

Pediatric

<18 years: Not recommended
>18 years: Administer as in adults

Interactions

Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism of fluoroquinolones; reduces therapeutic effects of phenytoin; probenecid may increase serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy

Ampicillin (Principen, Omnipen)

Bactericidal activity against susceptible organisms. Alternative to amoxicillin when unable to take medication PO.

Dosing

Adult

250-500 mg PO q6h
2 g IV/IM q4h
Not to exceed 12 g/d

Pediatric

50-100 mg/kg/d PO divided q4-6h
100-400 mg/kg/d IV/IM divided q4-6h

Interactions

Probenecid and disulfiram elevate levels; allopurinol decreases effects and has additive effects on ampicillin rash; may decrease effects of oral contraceptives

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adjust dose in renal failure; evaluate rash and differentiate from hypersensitivity reaction

Piperacillin and tazobactam sodium (Zosyn)

Inhibits biosynthesis of cell wall mucopeptide and is effective during stage of active multiplication.

Dosing

Adult

3/0.375 g (piperacillin 3 g and tazobactam 0.375 g) IV q6h

Pediatric

<12 years: Not established
>12 years: Administer as in adults

Interactions

Tetracyclines may decrease effects of piperacillin; high concentrations of piperacillin may physically inactivate aminoglycosides if administered in same IV line; effects when administered concurrently with aminoglycosides are synergistic; probenecid may increase penicillin levels; high-dose parenteral penicillins may result in increased bleeding risk

Contraindications

Documented hypersensitivity; severe pneumonia, bacteremia, pericarditis, emphysema, meningitis and purulent or septic arthritis should not be treated with an oral penicillin during the acute stage

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Perform CBC counts prior to initiation of therapy and at least weekly during therapy; monitor for liver function abnormalities by measuring AST and ALT during therapy; exercise caution in patients diagnosed with hepatic insufficiencies; perform urinalysis and BUN and creatinine determinations during therapy and adjust dose if values become elevated; monitor blood levels to avoid possible neurotoxic reactions

Ertapenem (Invanz)

Bactericidal activity results from inhibition of cell wall synthesis and is mediated through ertapenem binding to penicillin-binding proteins. Stable against hydrolysis by various beta-lactamases including penicillinases, cephalosporinases, and extended-spectrum beta-lactamases. Hydrolyzed by metallo-beta-lactamases.

Dosing

Adult

1 g qd for 14 d if IV and 7 d if IM; infuse over 30 min if IV
CrCl <30 mL/min/1.73 m²: 500 mg IV qd

Pediatric

<3 months: Not established
3 months to 12 years: 15 mg/kg IV q12h; not to exceed 1 g/d
>12 years: Administer as in adults

Interactions

Probenecid may reduce renal clearance of ertapenem and increase half-life but benefit is minimum and does not justify coadministration

Contraindications

Documented hypersensitivity to drug or amide type anesthetics

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Pseudomembranous colitis may occur; seizures and CNS adverse reactions may occur; when using with lidocaine to administer intramuscularly, avoid inadvertent injection into blood vessel; decrease dose in renal failure; serious and occasionally fatal hypersensitivity reactions may occur with beta lactams, caution with previous hypersensitivity reactions to penicillin, cephalosporins, other beta lactams, or other allergens; do not mix or coinfuse in same IV line as other medications; do not mix with dextrose-containing diluents

Imipenem and cilastatin (Primaxin)

For treatment of multi-organism infections in which other agents do not have wide-spectrum coverage or are contraindicated because of potential for toxicity.

Dosing

Adult

Base initial dose on severity of infection and administer in equally divided doses; dose may range from 250-500 mg q6h IV for a maximum of 3-4 g/d
Alternatively, 500-750 mg q12h IM or intra-abdominally

Pediatric

Infants >3 months and children <12 years: 15-25 mg/kg/dose IV q6h
Fully susceptible organisms: not to exceed 2 g/d
Infections with moderately susceptible organisms: not to exceed 4 g/d
>12 years: Administer as in adults

Interactions

Coadministration with cyclosporine may increase CNS side effects of both agents; coadministration with ganciclovir may result in generalized seizures

Contraindications

Documented hypersensitivity; known hypersensitivity to amide local anesthetics; children with CNS infections (increased seizure risk); children <30 kg with renal impairment (lack of data)

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Adjust dose in renal insufficiency (adult adjustments)
CrCl (mL/min) 80-50: 0.5 g q6-8h
CrCl 50-10: 0.5 g q8-12h
Hemodialysis (HD): 0.25-0.5 g after HD, then q12h
Adjust dose in renal insufficiency; avoid use in children <12 y with CNS infections
Caution with history of seizures, hypersensitivity to penicillins, cephalosporins, or other beta-lactam antibiotics

Minocycline (Dynacin, Minocin)

Treats infections caused by susceptible gram-negative and gram-positive organisms, in addition to infections caused by susceptible Chlamydia, Rickettsia, and Mycoplasma species.

Dosing

Adult

100 mg PO bid

Pediatric

<8 years: Not recommended
>8 years: 4 mg/kg PO initially, followed with 2 mg/kg q12h

Interactions

Bioavailability decreases with antacids containing aluminum, calcium, magnesium, iron, or bismuth subsalicylate; can decrease effects of oral contraceptives, causing breakthrough bleeding and increased risk of pregnancy; tetracyclines can increase hypoprothrombinemic effects of anticoagulants

Contraindications

Documented hypersensitivity; severe hepatic dysfunction

Precautions

Pregnancy

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Photosensitivity may occur with prolonged exposure to sunlight or tanning equipment; reduce dose in renal impairment; consider drug serum level determinations in prolonged therapy; tetracycline use during tooth development (last one-half of pregnancy through age 8 y) can cause permanent discoloration of teeth; Fanconilike syndrome may occur with outdated tetracyclines; hepatitis or lupuslike syndromes may occur

Cefoxitin (Mefoxin)

Second-generation cephalosporin with activity against some gram-positive cocci, gram-negative rod infections, and anaerobic bacteria. Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins; inhibits final transpeptidation step of peptidoglycan synthesis, resulting in cell wall death.
Infections caused by cephalosporin- or penicillin-resistant gram-negative bacteria may respond to cefoxitin.

Dosing

Adult

1-2 g IV/IM q6-8h or 1-2 g IV/IM q4h in severe cases

Pediatric

Infants and children: 80-160 mg/kg/d IV divided q4-6h; higher doses for severe or serious infections; not to exceed 12 g/d

Interactions

Probenecid may increase effects of cefoxitin; coadministration with aminoglycosides or furosemide may increase nephrotoxicity (closely monitor renal function)

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adjust dose in severe renal insufficiency (high doses may cause CNS toxicity); superinfections and promotion of nonsusceptible organisms may occur with prolonged use or repeated therapy

Sulfamethoxazole and trimethoprim (Bactrim, Bactrim DS, Septra, Septra DS)

Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid.
Antibacterial activity of TMP-SMZ includes common urinary tract pathogens, except Pseudomonas aeruginosa.

Dosing

Adult

160 mg TMP/800 mg SMZ (1 tab DS) PO q12h for 10-14 d

Pediatric

<2 months: Do not administer
>2 months: 10-20 mg TMP/kg/d PO/IV divided tid/qid for 14 d

Interactions

May increase PT when used with warfarin (perform coagulation tests and adjust dose accordingly); coadministration with dapsone may increase blood levels of both drugs; coadministration of diuretics increases incidence of thrombocytopenia purpura in elderly patients; phenytoin levels may increase with coadministration; may potentiate effects of methotrexate in bone marrow depression; hypoglycemic response to sulfonylureas may increase with coadministration; may increase levels of zidovudine

Contraindications

Documented hypersensitivity; megaloblastic anemia due to folate deficiency; age <2 mo

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Do not use during last trimester of pregnancy because of potential toxicity to newborn (eg, jaundice, hemolytic anemia, kernicterus)
Dosage adjustments (adult adjustments)
CrCl (mL/min) 80-50: Recommended IV dose q18h
CrCl 50-10: Recommended IV dose q24h
CrCl <10: Not recommended
HD: 4-5 mg/kg after HD
During peritoneal dialysis: 0.16-0.8 g q48h
Discontinue at first appearance of skin rash or sign of adverse reaction; obtain CBC counts frequently; discontinue therapy if significant hematologic changes occur; goiter, diuresis, and hypoglycemia may occur with sulfonamides; prolonged IV infusions or high doses may cause bone marrow depression (if signs occur, give 5-15 mg/d leucovorin); caution in folate deficiency (eg, chronic alcoholics, elderly, those receiving anticonvulsant therapy, or those with malabsorption syndrome); hemolysis may occur in G-6-PD deficient individuals; AIDS patients may not tolerate or respond to TMP-SMZ; caution in renal or hepatic impairment (perform urinalyses and renal function tests during therapy); give fluids to prevent crystalluria and stone formation

Azithromycin (Zithromax)

Acts by binding to 50S ribosomal subunit of susceptible microorganisms and blocks dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Nucleic acid synthesis is not affected.
Concentrates in phagocytes and fibroblasts as demonstrated by in vitro incubation techniques. In vivo studies suggest that concentration in phagocytes may contribute to drug distribution to inflamed tissues.
Treats mild-to-moderate microbial infections.

Dosing

Adult

500 mg PO qd

Pediatric

<6 months: Not established
>6 months:
Day 1: 10 mg/kg PO once; not to exceed 500 mg/d
Days 2-5: 5 mg/kg PO qd; not to exceed 250 mg/d

Interactions

May increase toxicity of theophylline, warfarin, and digoxin; effects are reduced with coadministration of aluminum and/or magnesium antacids; nephrotoxicity and neurotoxicity may occur when coadministered with cyclosporine

Contraindications

Documented hypersensitivity; hepatic impairment; do not administer with pimozide

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Site reactions can occur with IV route; bacterial or fungal overgrowth may result from prolonged antibiotic use; may increase hepatic enzymes and cholestatic jaundice; caution in patients with impaired hepatic function or prolonged QT intervals

Tigecycline (Tygacil)

A glycylcycline antibiotic that is structurally similar to tetracycline antibiotics. Inhibits bacterial protein translation by binding to 30S ribosomal subunit and blocks entry of amino-acyl tRNA molecules in ribosome A site. Complicated intra-abdominal infections caused by C freundii, E cloacae, E coli, K oxytoca, K pneumoniae, E faecalis (vancomycin-susceptible isolates only), S aureus (methicillin-susceptible isolates only), S anginosus group (includes S anginosus, S intermedius, and S constellatus), B fragilis, B thetaiotaomicron, B uniformis, B vulgatus, C perfringens, and P micros.

Dosing

Adult

Infuse each dose over 30-60 min
100 mg IV once, then 50 mg IV q12h
Severe hepatic impairment (ie, Child Pugh class C): 100 mg IV once, then 25 mg IV q12h

Pediatric

<18 years: Not established
>18 years: Administer as in adults

Interactions

Coadministration decreases warfarin clearance and increases warfarin C_max and AUC (monitor aPTT and INR); coadministration of antibiotics with oral contraceptives may decrease contraceptive effect

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Caution in severe hepatic impairment (reduce dose); may adversely effect tooth development; may permit clostridia overgrowth, resulting in antibiotic-associated colitis; may have adverse effects similar to tetracyclines (eg, photosensitivity, pseudotumor cerebri, pancreatitis, antianabolic action)

Follow-up

Further Outpatient Care

• Careful follow-up evaluations of extensive bites or deep puncture wounds from cat bites are mandatory for early diagnosis of tenosynovitis, septic arthritis, and osteomyelitis.

Complications

• Abscesses and tenosynovitis are the most common complications of P multocida soft-tissue infection. Septic arthritis and osteomyelitis are less common. CNS involvement with meningitis can occur. Dissemination is rare.

Prognosis

• Soft-tissue P multocida infections carry an excellent prognosis. Deeper wounds, especially hand infections, may be associated with prolonged morbidity.
• P multocida pulmonary infections, CNS involvement, bacteremia, and endocarditis carry a mortality rate of approximately 30%.

Patient Education

• For excellent patient education resources, visit eMedicine's Infections Center. Also, see eMedicine's patient education article Tetanus.

Miscellaneous

Special Concerns

• P multocida should be considered a potential etiologic agent of any local infection following cat and dog bites or licks and cat scratches.

Multimedia

Media file 1: Pasteurella multocida infection.

References

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Keywords

Pasteurella multocida infection, P multocida infection, pasteurellosis, coccobacillus, coccobacilli, bacterial infection, dog bite, cat bite, cat scratch, bite wound, animal bite wound, cat lick, pet wound, pet bite, meningitis, tetanus, rabies

Contributor Information and Disclosures

Author

Alexandre Lacasse, MD, MSc, Fellow in Infectious Diseases, University of Tennessee at Memphis
Alexandre Lacasse, MD, MSc is a member of the following medical societies: American College of Physicians, American Medical Association, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Coauthor(s)

Michael Gelfand, MD, FACP, Chief, Professor, Department of Internal Medicine, Division of Infectious Diseases, Methodist Healthcare of Memphis, University of Tennessee
Michael Gelfand, MD, FACP is a member of the following medical societies: American College of Physicians, American Medical Association, American Society for Microbiology, Infectious Diseases Society of America, and Southern Medical Association
Disclosure: Nothing to disclose.

Thomas Lafeber, MD, Consulting Staff, Wellstar Infectious Disease LLC
Thomas Lafeber, MD is a member of the following medical societies: American Medical Association, American Society of Transplantation, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

J Robert Cantey, MD, Chief of Infectious Disease, Veterans Affairs Medical Center, Director, Professor, Department of Medicine, Division of Infectious Diseases, Medical University of South Carolina
J Robert Cantey, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Society for Clinical Investigation, American Society for MOHS Surgery, Infectious Diseases Society of America, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Medical Editor

Larry I Lutwick, MD, Professor of Medicine, State University of New York, Downstate Medical School; Director, Infectious Diseases, Veterans Affairs New York Harbor Health Care System, Brooklyn Campus
Larry I Lutwick, MD is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Aaron Glatt, MD, Professor of Clinical Medicine, New York Medical College; President and CEO, Former Chief Medical Officer, Departments of Medicine and Infectious Diseases, New Island Hospital
Aaron Glatt, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physician Executives, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Association, American Society for Microbiology, American Thoracic Society, American Venereal Disease Association, Infectious Diseases Society of America, International AIDS Society, and Society for Healthcare Epidemiology of America
Disclosure: Nothing to disclose.

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

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