Immunocompetence requires a period of maturation. Efficient T-cell and B-cell responses require previous antigen exposure. Passive fetal immunity is imparted by maternal transfer of IgG during the third trimester (8). The level of IgG in premature infants is proportional to gestational age. Postnatally, IgG levels decline during the first 4 months. Prematurity is effectively a hypogammaglobulinemic state. These infants manifest suboptimal protection against gram-negative organisms and exhibit impaired opsonization, increasing the risk of infections from Streptococcus B, Escherichia coli, and Serratia. Serum concentrations of complement component peptides are decreased in the newborn period, but rise rapidly following birth. Low levels of complement adversely affect opsonization (8).

The fetus begins to produce IgM at 10 weeks gestation. However, at birth the infant only has 10% the normal adult level. The infant’s response to antigen is an elevation of IgM. IgA is not detected until near term and does not achieve normal levels until puberty. Diseases whose defenses depend primarily on secretory IgA, such as respiratory syncytial virus, remain prevalent throughout infancy.

Host susceptibility to infection can be predicted by the following variables: extremes of age, severity of disease, classification of physical status, presence of infection at other sites, prolonged preoperative hospitalization, malnutrition, morbid obesity, and immunosuppressive therapy, including exposure to transfusions. The Study on the Efficacy of Nosocomial Infection Control demonstrated that patients most clearly at risk for SSI are those with three or more concomitant diagnoses; those undergoing a clean-contaminated, contaminated, or dirty-infected procedure; or any procedure expected to last longer than 2 hours (3).

Many of the factors that predispose a surgical site to infection are under the control of the surgeon. Traditionally, disinfection of the patient’s skin, sterilization of surgical equipment, control of the operating room environment, use of prophylactic antibiotics, and expeditious operation have been used to prevent SSI. Preoperative shaving with a razor carries an SSI rate as high as 5.6% compared with 0.6% for those not shaved (3). Hair should not be removed unless it interferes with the operation. If hair removal is necessary, it should be done with electric clippers immediately before the procedure. An antiseptic should be used for skin preparation. Chlorhexidine gluconate achieves greater reduction in skin microflora and has longer residual activity than povidone-iodine (3). Alcohol is effective, fast acting, and inexpensive, but it is also flammable. Drying and evaporative heat loss can be problematic for small children. There is minimal evidence to support the view that antiseptic impregnated adhesive drapes or scrubbing all wounds affects the incidence of SSI.

Cleansing the hands of members of the operative team is imperative. Solutions containing chlorhexidine gluconate or an iodophor are most effective. These agents have the fewest problems with stability, contamination, and toxicity (3). Evidence suggests that a 2-minute scrub is sufficient, provided a brush is used to remove resident bacteria about the nail folds. Alcohols applied to skin are among the safest antiseptics, producing the greatest and most rapid reduction in bacterial counts on the skin. A 1-minute scrub with alcohol has been shown to be the most effective method for hand antisepsis.

Adherence to basic Halstedian principles decreases the risk for SSI. Hemostasis, sharp dissection, fine sutures, gentle tissue handling, and anatomic dissection can mitigate the development of tissue necrosis, seromas, or hematomas. Logarithmically, fewer bacteria are required to produce infection in the presence of a foreign body (i.e., suture, drain, catheter, graft, mesh) or necrotic tissue (poor hemostasis or thermal injury from electrocautery). Use of electrocautery to provide pinpoint coagulation or divide tissue under tension produces minimal tissue
destruction, no charring, and does not change the wound infection rate (9).

The surgeon and the operation are both capable of influencing the immunologic efficacy of the host. Contamination increases with time, and operations expected to last longer than 2 hours are at greater risk. Extremes of age, basal nutritional state, transfusion, and use of steroids or other immunosuppressive drugs, including chemotherapy, are associated with an increased risk for SSI (3).

Surgical antimicrobial prophylaxis refers to an agent administered prior to an operation whose function is to reduce the burden of contamination to a level manageable by host defenses. Antimicrobial prophylaxis anticipates the surgical wound class (Table 13-1). Prophylactic agents should be given 30 minutes prior to surgery to establish a bactericidal concentration of the drug in the tissues at the time of skin incision. A second dose is warranted if the operation lasts longer than 3 hours, exceeds twice the half-life of the antibiotic, or massive hemorrhage has occurred. No benefit has been demonstrated in continuing prophylaxis beyond the day of operation (3).

Prophylaxis is not indicated for clean operations, or if the operation does not involve placement of prosthetic materials. Cardiac operations, vascular procedures involving graft or stent placement, and neurosurgical operations and orthopedic procedures using hardware are notable exceptions. Clean cases that are at risk are in patients with more than three concomitant diagnoses, those whose operation will exceed 2 hours, and those whose operations are abdominal (3).

Antimicrobial prophylaxis is indicated for all clean-contaminated operations. Prophylaxis is appropriate for biliary procedures, including cholecystectomy (open or laparoscopic), common bile duct exploration/reconstruction, choledochal cyst excision, portoenterostomy, and pancreatic procedures. Gastroduodenal procedures warrant prophylaxis in patients with low gastric acidity, active hemorrhage, cancer, gastric ulcer, and obstruction (3). Patients undergoing procedures of the oral cavity, pharynx, and esophagus should receive preoperative antibiotics. In principle, urologic procedures in patients with sterile urine do not require antibiotics. Patients with documented urinary tract infections should be treated with culture-specific antibiotics. Gynecologic procedures are usually adequately covered with cephalosporins, tetracyclines, aqueous penicillin G, or metronidazole. In vaginal procedures, there is no added benefit to the use of a preoperative vaginal antiseptic over saline irrigation alone.

Certain clean-contaminated procedures involving the colon or rectum benefit from preoperative “bowel preparation” to reduce fecal mass and number of microorganisms. Most protocols employ mechanical cleansing, coupled with preoperative oral antibiotics or perioperative parenteral antibiotics. Mechanical cleansing can be performed by whole gut lavage using an electrolyte solution, polyethylene glycol or dietary restriction, cathartics, and enemas for several days before operation. In the pediatric population, bowel preparation may result in dehydration and electrolyte abnormalities. Infants and toddlers may require admission for intravenous hydration and monitoring.

Antibiotics are used to suppress both aerobes and anaerobes. There is no consensus on which agents to use or their route of administration. Oral regimens need to exhibit (1) rapid, highly bactericidal activity against gastrointestinal pathogens; (2), low local and systemic toxicity; and (3) limited gut absorption. Most oral regimens use neomycin and erythromycin base, or neomycin-metronidazole or kanamycin-metronidazole, given in three doses the day prior to operation (9). Parenteral antibiotics shown to be effective for elective colon resection include cefoxitin, cefotetan, and metronidazole, alone or in combination with an aminoglycoside.

Antimicrobial prophylaxis in contaminated or dirty cases is not indicated. Patients are frequently receiving therapeutic antibiotics for established infections. In colorectal procedures, a second-generation cephalosporin with activity against aerobes and anaerobes is recommended. For uncomplicated appendicitis, a single dose of cefoxitin or cefotetan, or in β-lactam allergic patients,
metronidazole, is effective. The combination of an aminoglycoside with clindamycin or metronidazole is effective for perforated appendicitis. Prophylaxis for an emergency laparotomy is best managed with an agent active against aerobes and anaerobes. When laparotomy is performed for nonpenetrating trauma, coverage for both aerobes and anaerobes is indicated and 24 hours or less of therapy is adequate. For penetrating abdominal injuries, treatment with cefoxitin, cefotetan, or a combination of agents active against both aerobes and anaerobes is recommended. Duration of use should again be limited to 24 hours. Open fractures with mild to moderate tissue damage should be managed with a first-generation cephalosporin. Combination therapy is appropriate for open fractures with gross contamination, major tissue damage or soft tissue loss. Major soft tissue injury is usually treated with parenteral cefazolin. Infected or dirty cases require a therapeutic course of antibiotics. Wounds with extensive contamination or tissue destruction should be left open for later inspection.

Patients with cardiac or vascular conditions and with intravascular prosthetic material should receive prophylactic antibiotics (9). In oral and dental procedures, viridans streptococci pose the greatest risk. The genitourinary or gastrointestinal tracts predispose to enterococcal infection (Table 13-2). Oral amoxicillin has replaced penicillin V and ampicillin because of its superior absorption and improved serum levels. In penicillin-allergic patients, clindamycin is recommended but clarithromycin, azithromycin, or cephalexin are acceptable alternatives. Exposure to enteric flora warrants parenteral ampicillin plus gentamicin. In penicillin-allergic patients, vancomycin is recommended, with gentamicin added in high-risk patients. For patients with a history of rheumatic fever, erythromycin rather than amoxocillin should be used to protect against endocarditis (9).

Appropriate surgical drain use and details of drain placement vary widely. Some general points should be emphasized. To minimize the risk of SSI, most authorities suggest placing drains through separate incisions distant from the primary wound. Closed suction drains are favored over open drains because they pose less potential for contamination and infection. Timing of drain removal is important because bacterial colonization of initially sterile drain tracts is a function of the duration of time a drain is kept in place (9).

Pneumonia is the most frequently encountered hospital-acquired infection, accounting for approximately one-third of all NI (10). The frequency of nosocomial pneumonia in pediatric patients ranges from 1% to 5% (12). In the NICU population, this rises to nearly 12%, primarily in low birth weight (less than 1,000 g) neonates (13). Specific risk factors for the development of nosocomial pneumonia include intubation and mechanical ventilation, admission to an intensive care unit (ICU), burns, immunosuppression, and central nervous system injuries.

Nosocomial respiratory tract infection is often diagnosed by clinical suspicion (i.e., new onset of purulent sputum) supported by microbiological studies (i.e., blood and sputum cultures). Chest radiography is a useful adjunct to diagnosis, especially in the absence of positive cultures. Alternative methods of diagnosis, including bronchoscopy and bronchoalveolar lavage, have not proven effective in the pediatric population (12).