Surgical Infections Flashcards
What types of surgical infections are of concern to pediatric surgeons?
Infection continues to be a significant source of mortality and morbidity for children despite improvements in antimicrobial therapy, aseptic surgical technique, and postoperative intensive care.
Widespread unchecked antibiotic use has led to the development of more resistant organisms, leading to a rather complex and arduous process of selecting the appropriate antibiotic, especially as newer antibiotics are continually developed.
In addition, infections with uncommon organisms are becoming more frequent with diminished host resistance from immunosuppressive states such as immaturity, cancer, systemic diseases, and transplant procedures.
Surgical infections, by definition, often require some operative intervention, such as incision and drainage (I&D) of an abscess or removal of necrotic tissue, and often do not respond to antibiotics alone.
Two broad classes of infectious disease processes affect surgeons: those infectious conditions brought to the pediatric surgeon for treatment and cure, and those that arise in the postoperative period as a complication of an operation.
Therefore, a good understanding of the infectious process is important.
H&A
What are the four important components of the pathogenesis of an infection?
The evolution of infection involves a complex interaction between the host and the infectious agent.
Four components are important: virulence of the organism,
size of the inoculum,
presence of a nutrient source for the organism, and
a breakdown in the host’s defense.
1) VIRULENCE
The virulence of any microorganism depends on its ability to cause damage to the host.
Exotoxins, such as streptococcal hyaluronidase, are digestive enzymes released locally by some organisms that allow the spread of infection by breaking down host extracellular matrix proteins.
Endotoxins, such as lipopolysaccharides, are components of gram-negative cell walls that are released only after bacterial cell death.
Once systemically absorbed, endotoxins trigger a severe and rapid systemic inflammatory response by releasing various endogenous mediators such as cytokines, bradykinin, and prostaglandins.
Surgical infections occasionally may be polymicrobial, involving various interactions among the microorganisms and toxins.
2) INOCULUM
The size of the inoculum is the second important component of an infection.
The number of colonies of microorganisms per gram of tissue is the key determinant.
Predictably, any decrease in host resistance decreases the absolute number of colonies necessary to cause clinical disease.
In general, if the bacterial population in a wound exceeds 100,000 organisms per gram of tissue, an invasive infection is present.
3) NUTRIENTS
For any inoculum, the environment determines the viability and survival. Therefore, the presence of suitable nutrients for the organism is essential and comprises the third component of any clinical infection.
Accumulation of necrotic tissue, hematoma, and foreign matter is an excellent nutrient medium for continued organism growth and spread.
Of special importance to the surgeon is the concept of necrotic tissue and infection.
When present at an infected site, this tissue often needs to be debrided to restore the host–bacterial balance and lead to effective wound healing.
Neutrophils, macrophages, and cytokines can then accumulate in necrotic tissue, initiating a secondary inflammatory response.
4) HOST DEFENSE
Finally, for a clinical infection to arise, the body’s defenses must be overwhelmed.
Even highly virulent organisms can be eradicated before clinical infection occurs if the host resistance is intact.
Evolution has fortunately equipped humans with numerous mechanisms of defense, both anatomic and systemic.
H&A
What are the anatomic barriers to infection?
ANATOMIC BARRIERS
Intact skin and mucous membranes provide an effective surface barrier to infection.
These tissues barriers are not merely a mechanical obstacle, but rather possess physiologic characteristics that provide an extra layer of protection.
In the skin, thermoregulation, the constant turnover of keratinocytes, and acid secretion from sebaceous glands inhibits bacterial cell growth.
The mucosal surfaces likewise have developed advanced defense mechanisms to prevent and combat microbial invasion, where specialized epithelial layers provide resistance to infection.
In addition, mechanisms such as the mucociliary transport system in the respiratory tract and normal colonic flora in the gastrointestinal tract prevent invasion of organisms.
Any alteration in the normal function of these anatomic barriers increases the host’s susceptibility to infection.
A skin injury or a burn provides open access to the underlying soft tissues, while antibiotic use disrupts normal colonic flora.
Fortunately, such breakdowns in surface barriers are dealt with by the second line of defense, the immune system.
H&A
How does the immune response serve as a barrier to surgical infections?
IMMUNE RESPONSE
The immune system involves complex pathways and many specialized effector responses.
The initial line of defense is the more primitive and nonspecific innate system, which consists primarily of phagocytic neutrophils and the serumbased complement system.
The neutrophil is able to rapidly migrate to the source of the infection and engulf and destroy the infecting organisms by phagocytosis.
In the complement system, cytokines, low molecular weight proteins including tumor necrosis factor (TNF), and many interleukins that attract and activate neutrophils, play a significant role in mediating the inflammatory response.
In addition, the complement system, when activated, initiates a sequential cascade that also enhances phagocytosis and leads to lysis of pathogens.
Neonates, particularly premature infants, have an immature immune system and are supported by the protective agents in human breast milk.
Humoral and Cell-Mediated Immunity
The more specialized, adaptive immune system involves a highly specific response to antigens as well as the eventual production of a variety of humoral mediators.
This specific, adaptive immunity has two major components.
The humoral mechanism (B-cell system) is based on bursa cell lymphocytes and plasma cells.
On the other hand, the cellular mechanism (T-cell system) consists of the thymic-dependent lymphocytes.
The adaptive immune system is an antigen-specific system that is regulated by the lymphocytes. A myriad of receptors on the T-cells that are matched to particular individual antigens create these specific responses. Furthermore, antibody production from B-cells enhances the antigen-specific interaction.
B-cell immunity is provided by antibodies. The first exposure of an antigen leads to the production of IgM antibodies, whereas subsequent exposure to the same antigen results in rapid production of IgG antibodies.
Humoral antibodies may neutralize toxins, tag foreign matter to aid phagocytosis (opsonization), or lyse invading cellular pathogens.
Plasma cells and non-thymic-dependent lymphocytes that reside in the bone marrow and in the germinal centers and medullary cords of lymph nodes produce the reactive components of this humoral system. These agents account for most of the human immunity against extracellular bacterial species.
The T-cell component of immunity is based on sensitized lymphocytes located in the subcortical regions of lymph nodes and in the periarterial spaces of the spleen. T-cells are specifically responsible for immunity to viruses, most fungi, and intracellular bacteria. They produce a variety of lymphokines, such as transfer factors, which further activate lymphocytes; chemotactic factors; leukotrienes; and interferons.
Immunodeficiencies
Susceptibility to infection is increased when one of the components of the host defense mechanism is absent, reduced in numbers, or dysfunctional.
Some of these derangements may be congenital in nature, although the majority are acquired as a direct result of medications, radiation, endocrine disease, surgical ablation, tumors, or bacterial toxins.
Immunodeficiencies from any cause significantly increase the risk of infection both in hospitalized and postoperative patients.
Mycotic (fungal) infections are an increasing problem, especially in immunocompromised pediatric patients.
Systemic diseases tend to cause secondary diminished host resistance by impacting the normal function of the immune system. For example, in diabetes mellitus, leukocytes often fail to respond normally to chemotaxis. Therefore, more severe, recurrent, and unusual infections often occur in diabetic patients.
In addition, malignancy and other conditions that impair hematopoiesis lead to alterations in phagocytosis, resulting in an increased predilection for infection.
Human immunodeficiency virus (HIV) infection in children is another major source of immunodeficiency. Vertical transmission from mother to child is the dominant mode of HIV acquisition among infants and children.
Finally, poor nutritional status has adverse effects on immune function owing to a wide variety of negative influences on specific defense mechanisms, including decreased production of antibodies and phagocytic function.
In patients with a primary immune defect, susceptibility to a specific infection is based on whether the defect is humoral, cellular, or a combination.
Primary immunodeficiencies are rare but important because prompt recognition can lead to lifesaving treatment or significant improvement in the quality of life.
B-cell deficiencies are associated with sepsis from encapsulated bacteria, especially pneumococcus, Haemophilus influenzae, and meningococcus.
Often a fulminating course rapidly ends in death, despite timely therapeutic measures.
Although congenital agammaglobulinemia or dysgammaglobulinemia has been widely recognized, chronic granulomatous disease (CGD) is another immunodeficiency caused by a diminished respiratory burst action of phagocytes that leads to severe and recurrent bacterial and fungal infections in early childhood.
Children with CGD are prone to develop hepatic abscesses as well as suppurative adenitis of a single node or multiple nodes, both of which may require drainage or excision.
Other secondary causes of humoral defects include radiation, corticosteroid and antimetabolite therapy, sepsis, splenectomy, and starvation.
T-cell deficiencies are responsible for many viral, fungal, and bacterial infections.
Cutaneous candidiasis is a good example of a common infection seen with a T-cell deficiency.
DiGeorge syndrome is a developmental anomaly in which both the thymus and the parathyroid glands are deficient, thus increasing the risk for infection and hypocalcemic tetany during infancy.
H&A
What are some considerations in the use of antibiotics for pediatric patients?
Antibiotics are classified based on their molecular structure, mechanism, and site of action.
The varying antibiotic classes can be divided into bacteriostatic (which inhibit bacterial growth) and bacteriocidal (which destroy bacteria).
The early initiation of the appropriate antibiotics is essential for timely and successful treatment of infections.
In addition, it is important to have sufficient knowledge of the specific susceptibility patterns in a particular hospital or intensive care unit to direct initial empirical antibiotic therapy.
Finally, awareness of interactions and adverse reactions in children from commonly used medications is also important.
Monitoring drug dosages in infants and children is important when treating them with antibiotics. The efficacy and safety of many drugs have not been established in children, especially in the newborn.
Dosages based on pediatric pharmacokinetic data offer the most rational approach.
Dosage requirements constantly change as a function of age and body weight.
Furthermore, the volume of distribution and half-life of many medications are often increased in neonates and children compared with adults for a variety of reasons.
Knowledge of a drug’s pharmacokinetic profile allows manipulation of the dose to achieve and maintain a given plasma concentration.
Newborns usually have extremely skewed drug-distribution patterns. The entire body mass can be considered as if it were a single compartment for the purposes of dose calculations.
For the majority of drugs, dose adjustments can be based on plasma drug concentration.
Administering a loading dose is advisable when rapid onset of drug action is required. For many medicines, loading doses are generally greater in neonates and young infants than in older children or adults.
However, prolonged elimination of drugs in the neonate requires lower maintenance doses, given at longer intervals, to prevent toxicity.
Monitoring serum drug concentrations is useful if the desired effect is not attained or if adverse reactions occur.
The neonate undergoing extracorporeal membrane oxygenation (ECMO) presents a special challenge to drug delivery and elimination. Because the ECMO circuit may bind or inactivate medicines and make them unavailable to the patient, dosing requires careful attention to drug response and serum levels.
On ECMO, the pharmacokinetics generally include a larger volume of distribution and prolonged elimination, with a return to baseline after decannulation.
H&A
What are methods to prevent surgical infections?
The most effective way to deal with infectious complications is to prevent their occurrence. The clinician must therefore be cognizant of the variables that increase the risk of infection and attempt to mitigate them.
The World Health Organization, American College of Surgeons, and Center for Disease Control all have recently published guidelines for prevention of surgical site infection (SSI).
PATIENT CHARACTERISTICS
In adults, comorbidities often increase the risk of a SSI. However, these chronic diseases are infrequently encountered in children.
A prospective multicenter study of wound infections in the pediatric population found that postoperative wound infections were more likely related to factors at the operation rather than to patient characteristics.
In this study of more than 800 children, the only factors associated with an increased SSI were contamination at the time of operation and the duration of the procedure.
Other investigators have similarly found that local factors at the time of operation, such as degree of contamination, tissue perfusion, and operative technique, play a more important role in initiation of an SSI than the general condition of the infant/child.
Attempting to reduce SSI with preoperative patient optimization continues to be a topic of investigation for surgeons.
Adults with positive nasal methicillin-resistant Staphylococcus aureus (MRSA) have been shown to have a higher chance of MRSA SSI; however, the rate of MRSA SSI was <2% in one study.
Recent pediatric evidence suggest there is no correlation between positive nasal swabs and wound infection for elective surgeries, and Staphylococcus aureus eradication may not be needed preoperatively.
SURGICAL PREPARATION
Preoperative preparation of the surgical site and the sterility of the surgical team are very important in reducing the risk of postoperative infection.
Hand hygiene remains the most important proactive mechanism to reduce infection by reducing the number of microorganisms present on the skin during an operation.
In the United States, the conventional method for surgical team scrubbing has been a 5-minute first scrub followed by subsequent 2- or 3-minute scrubs for subsequent cases with either 5% povidone-iodine or 4% chlorhexidine gluconate.
These scrubbing protocols can achieve a 95% decrease in skin flora.
However, newer alcohol-based antiseptic cleaners with shorter applications, usually 30 seconds, have been shown to be as effective as, or even more effective than, hand washing in decreasing bacterial contamination.
A recent Cochrane review reported no firm evidence that one type of hand antisepsis was better than the other in reducing SSI.l
Normothermia has also been suggested as a means to decrease the incidence of wound infections.
Infants and children are at particular risk for experiencing hypothermia during surgery due to an increased area-to-body weight ratio leading to greater heat loss.
Intraoperative hypothermia can potentially lead to serious complications, including coagulopathy, SSIs, and cardiac complications.
A prospective randomized trial of 200 adult patients undergoing colorectal surgery showed that intraoperative hypothermia caused delayed wound healing and a greater incidence of infections.
A number of techniques are available to warm infants and children during their operation, including warming intravenous fluids or using forced-air warming systems.
In addition, supplemental oxygen given during the perioperative period in adults has been shown to decrease the rate of wound infection by as much as 40–50%.
Finally, adequate control of glucose levels perioperatively has also been demonstrated to decrease morbidity and mortality in both adult and pediatric surgical patients, particularly in those patients undergoing cardiac surgery.
H&A
What are the classes of wound infection?
The infection risk for operative cases can be stratified into one of four levels (Table 9.1), with the risk of SSI increasing with each higher classification level.
Preoperative wound classification has commonly been used for SSI risk stratification, which is now used as a quality measure by hospitals and third-party payors.
Classifying the operation has also been incorporated into the routine preoperative time-out sessions.
Historically, the estimated SSI rate for the surgical wound classifications were:
1–5% (Level I),
3–11% (Level II),
10–17% (Level III), and
>27% (Level IV).
However, a recent study using the American College of Surgeon National Surgical Quality Improvement Program (ACS-NSQIP) showed that superficial SSI rates were 1.76%, 3.94%, 4.75%, and 5.16%, respectively.
In the pediatric population, surgical wound classification discrepancies have been identified in multiple common procedures, especially in laparoscopic procedures.
A multicenter study showed a total surgical wound classification concordance of 56% with variability between institutions and procedures.
Also, correlation of the wound classes with risk of surgical infection remains imprecise in children.
Although quality improvement (QI) initiatives have improved wound classification concordance, there is still a need for caution in using surgical wound classification as a quality benchmark.
H&A
What are the classes of wound infection?
WOUND CLASSIFICATION
The infection risk for operative cases can be stratified into one of four levels (Table 9.1), with the risk of SSI increasing with each higher classification level.
Preoperative wound classification has commonly been used for SSI risk stratification, which is now used as a quality measure by hospitals and third-party payors.
Classifying the operation has also been incorporated into the routine preoperative time-out sessions.
Historically, the estimated SSI rate for the surgical wound classifications were:
1–5% (Level I),
3–11% (Level II),
10–17% (Level III), and
>27% (Level IV).
However, a recent study using the American College of Surgeon National Surgical Quality Improvement Program (ACS-NSQIP) showed that superficial SSI rates were 1.76%, 3.94%, 4.75%, and 5.16%, respectively.
In the pediatric population, surgical wound classification discrepancies have been identified in multiple common procedures, especially in laparoscopic procedures.
A multicenter study showed a total surgical wound classification concordance of 56% with variability between institutions and procedures.
Also, correlation of the wound classes with risk of surgical infection remains imprecise in children.
Although quality improvement (QI) initiatives have improved wound classification concordance, there is still a need for caution in using surgical wound classification as a quality benchmark.
H&A
What is the role of antibiotic prophylaxis in pediatric surgery?
ANTIBIOTIC PROPHYLAXIS
In adults, several well-designed prospective trials have documented a decreased incidence of infection for all types of operative procedures when established antibiotic recommendations are used.
Important points for preoperative antibiotic prophylaxis include using agents that cover the most probable intraoperative contaminants for the operation, optimal timing for the initial dose of antibiotic so that bactericidal concentrations are reached at the time of incision, and maintaining the appropriate serum levels throughout the operation.
Timing of the perioperative antibiotic coverage is crucial. The first dose is generally given 30 minutes to 1 hour before the start of the operation.
In operations that take more than the half-life of the administered drug, a second dose of prophylactic antibiotics is needed to reachieve adequate serum levels.
Prophylaxis accounts for nearly 75% of antibiotic use on pediatric surgical services.
Complete compliance with antibiotic prophylaxis decreases SSI by 30%.
Yet, the rate of complete compliance has been found to be as low as 6.5%.
Prophylaxis is also the major cause of the inappropriate use of antimicrobials in children with prophylactic antibiotics being administered inappropriately 40–52% of children receiving preoperative antibiotics.
A recent retrospective database review showed that there continues to be a national variation in the overall and appropriate use of antibiotic prophylaxis.
Evidence suggests that a multidisciplinary approach to antibiotic prophylaxis guidelines can increase compliance within a children’s hospital.
In pediatric surgery, it is clear that antibiotic coverage is required during clean-contaminated, contaminated, or dirty cases.
Antibiotic prophylaxis in clean cases, such as inguinal hernias, orchiopexy, and laparoscopic pyloromyotomies, has not been shown to decrease SSI and is probably not warranted.
H&A
What are the recommendations for bowel preparation in pediatric surgery?
BOWEL PREPARATION
The current bowel prep recommendations for adults undergoing an elective colorectal operation is combined isosmotic mechanical bowel prep along with oral antibiotics.
The bowel prep includes mechanical irrigation and flushing of the colon to remove stool, oral antibiotics against colonic aerobes and anaerobes, and preoperative intravenous antibiotics that cover both common skin and colonic flora.
A recent large retrospective database study found that mechanical bowel preparation along with oral antibiotics reduced SSI, anastomotic leak, and ileus for adult elective colorectal cases in comparison to mechanical bowel preparation alone and no mechanical bowel prep.
In infants and children, protocols for bowel preparation have largely been extrapolated from the adult colorectal literature.
Unfortunately, there continues to be variability in the use and type of bowel preparation used at children’s hospitals and among pediatric surgeons.
Only 9–19% of patients are receiving a mechanical bowel prep with oral antibiotics.
Recent randomized trials comparing mechanical bowel preparation versus no prep found no increased risk of infectious complications and postoperative outcomes.
However, none of the studies included an arm that used mechanical bowel prep and oral antibiotics.
Future studies should focus on comparing the current recommendations versus no preparation to determine whether bowel preparation is necessary in children.
If bowel preparation is used in infants and children, care must be taken to avoid dehydration.
H&A
How do you manage postoperative surgical site infections?
POSTOPERATIVE SURGICAL SITE INFECTION
Despite meticulous technique and perioperative antibiotics, infectious complications still occur.
Postoperative wound infections can be divided into superficial or deep.
Early diagnosis and prompt intervention help to avoid morbidity and occasional mortality.
Erythema, fever, leukocytosis, tenderness, crepitus, and suppuration are concerning diagnostic signs but are not always present.
When confronted with one or more of these signs, clinical judgment is important.
Treatment may include oral or intravenous antibiotics, I&D, or extensive surgical debridement with supportive wound care.
An abscess is a localized collection of pus in a cavity formed by an expanding infectious process.
Pus is a combination of leukocytes, necrotic material, bacteria, and extracellular fluid.
The usual cause is the staphylococcal species, especially methicillin-susceptible Staphylococcus aureus and MRSA.
The Infectious Diseases Society of America (IDSA) practice guidelines recommend I&D for purulent skin and soft tissues infections.
Historically, I&D procedures included wound packing, which can be painful and anxiety provoking for children.
Current evidence suggest that several techniques (stab incisions and placement of a drain, placement of Wound V.A.C.© , and even no packing) have been found to have similar resolution of an abscess with a low recurrence rate while avoiding cumbersome wound care when compared with packing.
IDSA guidelines currently do not recommend antibiotic therapy after abscess drainage for “mild” infections.
However, they do recommend antibiotics after drainage if the abscess is associated with systemic signs of infection or the patient is immunocompromised.
A phlegmon is an area of diffuse inflammation with little pus and some necrotic tissue. A phlegmon can often be treated with antibiotics, although it can progress to an abscess, which may require I&D.
Streptococcal soft tissue infections are probably the most virulent and can arise within a few hours after a surgical procedure. High fever, delirium, leukocytosis, and severe pain are hallmarks of these infections.
Bacillus infections are the next most virulent infection. Inspection of the wound will show dark, mottled areas, as opposed to the bright pink of a streptococcal cellulitis.
Fewer than half of patients with Bacillus infections have detectable gas crepitation.
Severe pain is the most telling clinical symptom of this type of infection.
High doses of penicillin and operative debridement of the necrotic tissue are the hallmarks of treatment for these patients.
H&A
How do you manage nosocomial infections?
NOSOCOMIAL INFECTION
Nosocomial infections are defined as those infections that are hospital acquired.
As such, they are a potential threat to all hospitalized patients and significantly increase morbidity and mortality.
Their incidence appears to be increasing as surgical care becomes more complicated and patients survive longer.
The recent focus on patient safety has made prevention of nosocomial infections increasingly important.
One report describing 676 operative procedures in 608 pediatric patients showed a nosocomial infection rate of 6.2%.
The infectious complications included septicemia, pulmonary, urinary tract, abdominal, and diarrhea.
The highest overall occurrence of infection was in the infant group.
The most common isolates were Staphylococcus epidermidis from septic patients and gram-negative enteric bacteria from organ and wound infections.
Infection was associated with impaired nutrition, multiple disease processes, and multiple operations.
In addition, ECMO use has been shown to correlate with an increased incidence of nosocomial infection, as does the length of the preoperative hospitalization and exposure to invasive medical devices.
Pneumonia can be a lethal nosocomial infection, with mortality ranging from 20–70%, and accounting for 10–15% of all pediatric hospital-acquired infections (HAIs).
The mortality rate is dependent on the causative organism.
The risk factors for nosocomial pneumonia in the pediatric population include serious underlying illness, immunosuppression, and length of time on a ventilator.
Measures to prevent ventilator-associated pneumonia in children include elevating the head of the bed, daily assessment of readiness for extubation, and age-appropriate mouth care.
Clostridium difficile is a well-recognized cause of infectious diarrhea that develops after antibiotic therapy in many patients, although it likely accounts for only 15–25% of antibiotic-associated diarrhea.
It is a very common cause of HAI, and its incidence is increasing in frequency with associated increasing mortality.
The best method of prevention is the judicious and appropriate use of antibiotics.
To decrease HAI, the Centers for Medicare and Medicaid Services (CMS) released a proposal in 2008 to expand the list of hospital-acquired conditions that will not be reimbursed by Medicare.
These have been termed “Never Events” and include SSIs after specific elective surgeries, extreme glycemic aberrancies, ventilator-associated pneumonia, and C. difficile-associated diseases, among others.
Under this proposal, CMS will not reimburse hospitals for treatment (medical or surgical treatment) of these nosocomial entities.
H&A
How do you manage catheter infections?
CATHETER INFECTIONS
Central venous catheters (CVCs) are essential for managing critically ill patients.
CVCs include peripherally inserted CVC (PICC), nontunneled/ tunneled CVC, and venous access ports.
The use of CVCs in infants and children has increased as prolonged vascular access has become increasingly necessary to provide parenteral nutrition, chemotherapy, antimicrobial therapy, and hemodynamic monitoring.
However, central-line associated blood stream infections (CLABSIs) are common, despite considerable effort to reduce their occurrence, and are associated with increased hospital costs, length of stay, and morbidity/mortality.
CLABSIs are manifested as erythema at the site of insertion, tachycardia, and/or leukocytosis.
Rates of infection are influenced by patient-related factors, by type and severity of illness, and by catheter-related parameters (catheter type, purpose, and conditions under which it was placed).
Coagulase-negative staphylococci, followed by Staphylococcus aureus, were the most frequently isolated causes of hospital-acquired blood stream infections in a report from the National Nosocomial Infections Surveillance System.
A number of factors are associated with the development of CLABSIs, including the sterility of the insertion technique, type of solution being administered through the line, care of the catheter once inserted, proximity of the catheter to another wound, and the presence of another infection elsewhere.
Updated guidelines for the prevention of intravascular catheter-related infections were published in 2014.
For catheters that will remain for a long time, tunneling the catheter has been shown to significantly reduce the risk of catheter-related infection.
Absolute sterile techniques should be maintained in all instances of line insertion whenever possible.
Emergency situations may necessitate less-than-sterile technique.
The use of maximal sterile barriers, including sterile gown, gloves, and a large sterile sheet, has been shown in adults to greatly reduce the risk of CLABSI.
The single most important factor in preventing CLABSI is hand hygiene. Standardized hand hygiene programs in neonatal care units have been found to decrease CLABSI rates.
Studies suggest that chlorhexidine, compared with povidone-iodine, significantly reduces the incidence of CLABSI and microbial colonization, and 2% chlorhexidine preparations with alcohol are now recommended for skin antisepsis.
Chlorhexidine is frequently used in the neonatal intensive care unit (NICU) even though the safety and efficacy of chlorhexidine in infants <2 months is not known.
In infants, the most common adverse effect of chlorhexidine is skin irritation. However, in a small study Chapman et al. reported no skin irritation after chlorhexidine exposure.
Even with chlorhexidine being used with increased frequency in infants, further studies are needed to strengthen the evidence for its efficacy in this patient population.
The skin and catheter hub are the most common sites/ sources of colonization and infection. Thus, various methods have been used to combat these risks.
Chlorhexidine bathing has been shown to decrease CLABSI rates in the NICU, but its efficacy is unknown for children in the nonICU setting.
There is also some evidence to suggest that the use of medication-impregnated dressings reduce CLABSI in comparison to other type of dressings.
Silver ions have broad antimicrobial activity, and silver-impregnated cuffs have been designed as a preventive measure.
Such antimicrobial and antiseptic impregnated catheters and cuffs may decrease the incidence of catheter-related infections.
However, in one study, chlorhexidine dressing/alcohol skin cleansing in newborn infants only reduced catheter colonization with no difference in CLABSI.
Catheters have been coated with chlorhexidine/silver sulfadiazine as well as minocycline/rifampin along with other agents.
The use of these antibacterial-coated catheters has been approved by the U.S. Food and Drug Administration for use in patients weighing >3 kg.
It is likely that the efficacy for reducing infection decreases after being in place for longer than 3 weeks because of a decrease in the antimicrobial activity.
These impregnated catheters and sponge dressings can be used if the infection rate is not decreasing with other measures.
The interval between dressing changes around CVC and its association with CLABSI has been another contentious issue.
Current recommendations allow less frequent dressings changes in selected NICUs to reduce the risk of catheter dislodgement.
A recent Cochrane review, however, found inconclusive evidence with regard to length of interval between dressing changes and the CLABSI rate.
The routine use of prophylactic antibiotics with CVC placement is also controversial.
No studies in adults have demonstrated a benefit for systemic antibiotic prophylaxis after insertion of a CVC.
Studies in high-risk neonates and children have demonstrated conflicting results.
However, concern exists for the emergence of antibiotic resistance with the routine use of antimicrobial prophylaxis.
Catheter-associated urinary tract infection (CAUTI) is the most common overall type of catheter related infection, but with a low incidence in children (0.2–1.3%).
The most common pathogen is Escherichia coli followed by Candida albicans.
Children on average stayed 2 days longer in the hospital and with an average hospital cost of $7200 due to CAUTI.
A recent QI project reduced CAUTI rates by implementing a prevention bundle.
Similar to central lines, adding an ethanol lock to urinary catheters has been shown to be safe, and further studies are needed to evaluate if the ethanol lock reduces the rate of CAUTI.
H&A
How do you manage necrotizing soft tissue infections?
Necrotizing Soft Tissue Infection
Necrotizing soft tissue infection (NSTI) is a rapidly progressing infection of the fascial tissues and overlying skin, with a hospital mortality of 7%.
Although these infections can occur as a postoperative complication or as a primary infection, necrotizing fasciitis is more likely in immunocompromised patients.
However, in the pediatric population, necrotizing fasciitis often affects previously healthy children and infants.
Because the diagnosis is often not obvious, the physician must look for clinical clues such as edema beyond the area of erythema, crepitus, skin vesicles, or cellulitis refractory to intravenous antibiotics.
Skin necrosis is generally a late sign and is indicative of thrombosis of vessels in the subcutaneous tissue.
Necrotizing fasciitis often occurs in the truncal region in children as opposed to adults, in whom infection in the extremities is most common.
A validated NSTI scoring system called the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) was developed to objectively diagnose NSTI.
However, this score was derived from adult data and is not widely used in children.
Putnam et al. recently developed the pediatric LRINEC scoring system, which showed a C-reactive protein >20 mg/L as the most sensitive value and a sodium level <135 mEq/L as the most specific laboratory values for improving the diagnostic accuracy of NSTI in children.
Although infections with a single organism often occur in adults with necrotizing fasciitis, polymicrobial infections predominate in children.
Prompt surgical intervention, including wide excision of all necrotic and infected tissue, along with the institution of broad-spectrum antibiotics, is important to avoid progression and mortality.
Necrotizing fasciitis can also occur as a complication of chickenpox.
In neonates, necrotizing fasciitis is seen secondary to omphalitis, balanitis, and fetal monitoring.
H&A
How do you manage sepsis in the pediatric patient?
Sepsis Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection.
The 2012 Surviving Sepsis Campaign guidelines included special considerations for children with sepsis.
The diagnostic criteria for sepsis differ for the pediatric population and are defined as:
signs and symptoms of inflammation plus
infection with hypo- or hyperthermia, tachycardia, and organ dysfunction (altered mental status, hypoxemia, increased serum lactate, or bounding pulses).
Although there has been a decrease in the mortality rate among children with sepsis, the prevalence of severe sepsis in children has risen.
Neonatal sepsis is defined as a generalized bacterial infection accompanied by a positive blood culture within the first month of life.
Neonatal sepsis occurring during the first week of life is caused primarily by maternal organisms transferred during delivery.
Maternal contamination can be transmitted through the placenta to the newborn via the birth canal or by direct contamination of the amniotic fluid.
The mortality of this early onset sepsis approaches 50%.
Late-onset neonatal sepsis is primarily nosocomial and is most often secondary to indwelling catheters or bacterial translocation from the gut.
In the surgical neonate, three factors promote bacterial translocation and sepsis:
(1) intestinal bacterial colonization and overgrowth,
(2) compromised host defenses, and
(3) disruption of the mucosal epithelial barrier.
The mortality associated with lateonset sepsis approaches 20%.
The clinician must be alert for the subtle signs and symptoms of neonatal sepsis, which include lethargy, irritability, temperature instability, and a change in respiratory or feeding pattern.
Neonates may not demonstrate leukocytosis.
Empirical broad-spectrum coverage may be started, pending the results of blood and other cultures.
H&A
A patient presents with fever, chills, and extreme pain 48 hours after cutting his hand. His hand is purplish in color with bullae, putrid discharge, and decreased sensation. In addition to starting empiric antibiotics, what is the most appropriate management of this patient?
Choices:
1. CT scan of the hand
2. Serial examinations to assess for progression
3. Surgical exploration
4. Incision and drainage to send specimen for culture and Gram stain
Answer: 3 - Surgical exploration
Explanations:
• This is a case of necrotizing fasciitis. It is a rapidly spreading infection along deep fascial planes with subcutaneous tissue necrosis.
It typically is caused by Streptococcus pyogenes or Staphylococcus aureus, but anaerobes and Clostridium species may also be present.
• Urgent surgical exploration is indicated with aggressive debridement and should not be delayed for culture or radiographic results.
• A CT scan will not reveal anything new that can change surgical management.
• The patient must be aggressively resuscitated and undergo aggressive debridement. A second-look procedure may be required in 24 to 48 hours.
Statpearls
A patient presents with fever, chills, and extreme pain 48 hours after cutting his hand. His hand is purplish in color with bul-lae, putrid discharge, and decreased sensation. In addition to starting empiric antibiotics, what is the most appropriate management of this patient?
Choices:
1. CT scan of the hand
2. Serial examinations to assess for progression
3. Surgical exploration
4. Incision and drainage to send specimen for culture and Gram stain
Answer: 3 - Surgical exploration
Explanations:
• This is a case of necrotizing fasciitis. It is a rapidly spreading infection along deep fascial planes with subcutaneous tissue necrosis.
It typically is caused by Streptococcus pyogenes or Staphylococcus aureus, but anaerobes and Clostridium species may also be present.
• Urgent surgical exploration is indicated with aggressive debride-ment and should not be delayed for culture or radiographic results.
•A CT scan will not reveal anything new that can change surgical management.
•The patient must be aggressively resuscitated and undergo aggressive debridement. A second-look procedure may be required in 24 to 48 hours.
StatPearls
What is the treatment for hydatid disease?
Hydatid disease is generally caused by infection with the larval stage of the dog tapeworm Echinococcus granulosis.
The ingested ova burrow through the intestinal mucosa and travel to the liver through the mesenteric veins.
A few ova may bypass the liver and be trapped in the lung.
The reported peak incidence of echinococcal infection in children is between 5 and 15 years of age.
The liver is involved in about 60% of the cases, the lung in about 20%, and other organs (kidney, brain, bone, or muscle) in about 20% of the cases. A solitary cyst will develop in one organ about 80% of the time.
The host organ separates itself from the parasite by forming a pericyst, which is a capsule of native connective tissue. For most surgical procedures, the pericyst is left behind and the intraluminal contents of the cyst are removed.
The usual presenting symptoms include right upper quadrant pain, a mass, and right pleuritic type chest pain in about one half of the patients. Interestingly, about a fourth of the patients are asymptomatic at presentation. Untreated cysts tend to grow until they reach the surface of the liver, where they can then spontaneously rupture, resulting in dissemination of the parasite into the peritoneal cavity and possible anaphylaxis.
In one fourth of the cases, the cyst can become secondarily infected with bacteria.
Echinococcal liver abscess is best diagnosed by serologic testing. The indirect hemagglutination assay is the most specific test, but it lacks sensitivity for echinococcal disease. Results are considered positive for tissue invasion at a titer of 1:512, suspicious at a titer of 1:128, and negative at a titer of 1:32. Additional tests include an enzyme-linked immunosorbent assay (ELISA), which has been reported to be positive in 96% of patients, or a compliment fixation test, which has an 89% positivity rate.
Sunita and colleagues have also reported excellent results using urine and saliva for ELISA antibody testing. The combination of two positive serologic tests provides a laboratory diagnosis in more than 94% of patients with echinococcal disease.
Diagnostic aspiration is indicated if there is concern that the cyst could be a pyogenic or amebic abscess, but it is not indicated for echinococcal disease. Abdominal US or CT is the diagnostic imaging modality of choice.
A plain film of the abdomen or abdominal CT may show calcification of the rim of an echinococcal cyst or daughter cysts that is not found in amebic liver abscess.
The definitive treatment of hepatic hydatid disease is surgical. Medical treatment of hydatid cyst includes the second-generation anthelmintic albendazole. Albendazole has been shown to be most effective in decreasing recurrent disease when it is given both preoperatively and postoperatively.
Successful operative management starts with isolation of the liver from the rest of the abdomen, usually with sponges soaked in hypertonic saline or a povidone-iodine (Betadine) solution to prevent spillage of the cyst material. The cyst fluid is then aspirated. The cyst is then opened 2 to 3 cm and the remaining contents including the laminated membrane are removed. The cavity is then flushed with 20% saline; however, the effectiveness of this step has been questioned.
The cavity then needs to be obliterated using one of several different techniques: closed suction drainage (cystostomy with drainage), obliteration with absorbable sutures (cystostomy with capitonnage), placement of an omental flap over the residual cavity (cystostomy with omentoplasty), or total excision of the entire cyst (cystectomy).
When cystostomy is performed, the cyst wall needs to be carefully inspected for any open biliary radicals. If found, they are individually sutured closed.
Recurrence rates after surgical excision of hepatic hydatid cysts have been reported to range from 1.1% to 9.6%.
When surgery and albendazole treatment are combined, the hepatic recurrence rate can be lowered to 2%.
Coran
