Nosocomial Infections

Nosocomial Infections I.

Pathophysiology A.

Factors predisposing NICU infants to nosocomial infections include each of the following: 1.

Immaturity of humoral and cellular immune defense mechanisms

2.

Breach of natural mucous membrane and skin barrier defense barriers

3.

Instrumentation with foreign bodies (endotracheal tubes, intravascular catheters)

4.

Alteration of"normal" flora through antimicrobial pressure (frequent use of empiric antibiotics)

5.

Overgrowth of Candida spp. Promoted by use of steroids and broad spectrum antibiotics

6.

High census, crowding, suboptimal nurse: patient ratios that promote transmission of nosocomial organism from one infant to another through poor handwashing

7. B.

Environmental contamination

Universal precautions have been renamed "standard precautions," because these precautions are recommended for all patients to protect health care workers from infectious body fluids. These apply to all body fluids, secretions, and excretions, non-intact skin and mucous membranes. The following techniques are included:

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1.

Hand washing (whether or not gloves are worn)

2.

Gloves should be worn when touching blood, body fluids, secretions, excretions, and items contaminated with these fluids.

3.

Masks, eye protection and face shields if eyes, nose, and mouth are likely to be sprayed during patient care activities

4.

Non-sterile gowns during procedures

5.

Patient care equipment should be handled in a manner that prevents skin and mucous membrane exposures and contamination of clothing

6.

Blood-borne pathogen exposure should be avoided

7.

Mouthpieces, resuscitation bags, and other ventilation devices should be available (no mouth to mouth)

C.

Appropriate precautions for MRSA infections include: 1.

Isolation in a separate room (private room or isolation unit)

2.

Contact precautions to control transmission which includes (1) gloves at all times, (2) hand washing with an antimicrobial agent after glove removal, (3) gowns at all times

3.

Contact transmission, the most important and frequent route of transmission in nosocomial infections, has two modes: direct and indirect

D.

Airborne precautions are used for M. tuberculosis, rubeola and varicella including:

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E.

1.

Private room

2.

Negative air-pressure ventilation (minimum: 6 changes per hour)

3.

Masks at all times

4.

Respirator masks for pulmonary tuberculosis

Droplet precautions should be used when organisms from infected person (sneezing, coughing) are propelled a short distance and deposited on health care worker's mucosa (eg, N. meningitidis, diphtheria, pertussis, respiratory viruses, rubella, streptococcal pharyngitis or scarlet fever). Specific precautions to be used are:

F.

1.

Private room (preferred)

2.

Use of a mask if within 3 feet of patient

Strategies for controlling the outbreak would be to encourage the following: 1.

Adherence to hand washing policy and other contact precautions

2.

Minimize number of persons with access to infected patients

3.

Surveillance of all NICU infants for MRSA infection

4.

Isolation of MRSA infected infants

5.

Cohorting of admissions into "clean" areas

6.

Dedicate specific health-care workers to provide one-on-one care for infected infants

7.

Educate all personnel caring for NICU patients as to the importance of control measures for MRSA

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8.

Ensure sufficient space between infant beds (4 to 6 ft)

9.

Diminish census and optimize nurse:infant ratios

10. Monitor compliance with control measures References 1.

American Academy of Pediatrics. Infection control for hospitalized children. In: Peter G (ed), 1997 Red Book: Report of the Committee on Infectious Diseases. 24th ed. Elk Grove Village, IL 1997:100-107.

2.

Donowitz LG. Pediatric infection control. In: Principles and Practice of Infectious Diseases. Long SS, Pickering LK, Prober CG (eds). New York: Churchill Livingstone, 1997:19-31.

Varicella Exposure II.

Infection Control A.

Employee illnesses that preclude work include conjunctivitis, diarrhea and vesicular rashes.

B.

All pediatric health care workers should be screened by history and/or serologic testing to document their immune status to specific infectious agents. Vaccination should be provided for all employees who are nonimmune to specific agents and who do not have contraindications to receiving a specific vaccine. These infectious agents are diphtheria, tetanus, hepatitis A and B, mumps, polio, rubella, rubeola and varicella. Tuberculosis screening and assessment at regular intervals should be included. Annual

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influenza vaccination also is indicated for all pediatric health care workers. C.

The following control measures are recommended after inadvertent nosocomial exposure to a health care worker infected with varicella: 1.

Personnel and patients who have been exposed and are susceptible to varicella should be identified.

2.

Varicella-zoster immune globulin (VZIG) should be administered to appropriate candidates.

3.

All exposed and susceptible patients should be discharged as soon as possible.

4.

Exposed susceptible patients who cannot be discharged should be placed in strict isolation from day 8 through 21 after exposure (day 28 if VZIG given).

5.

Exposed susceptible health care workers should be furloughed or excused from patient contact from day 8 through 21 after exposure (day 28 if VZIG is given).

6.

Varicella vaccine is recommended for susceptible personnel if varicella does not develop from the exposure.

D.

Candidates for VZIG after a significant exposure has occurred include: 1.

Immunocompromised children without history of chickenpox (including HIV-infected)

2.

Susceptible, pregnant women.

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3.

Newborn infants whose mothers had onset of varicella within the 5 days before or within 48 hours after delivery.

4.

Hospitalized premature infants (>28 weeks of gestation) whose mothers have no history of varicella or who are seronegative.

5.

Hospitalized premature infants (< 28 weeks of gestation or <1,000 grams), regardless of maternal history.

E.

Exposure is defined as face-to-face contact with an infectious person. Experts differ in the duration of contact that warrants administration of VZIG, some suggesting five or more minutes and others one or more hours.

F.

Respiratory secretions are a common mode of transmission for viral pathogens in the hospital environment. Adenovirus, influenza viruses, RSV, enteroviruses and varicella viruses, among others, are transmitted by respiratory secretions. Direct contact also may transmit infection in the cases of lesion secretions from varicella and purulent-exudates from adenovirus conjunctivitis. Fecal pathogens, such as rotavirus or enteroviruses may be spread by contact with feces.

Catheter-induced Infection: Narrative I.

Clinical Evaluation A.

The clinical manifestations of infections associated with CNS catheters include:

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1.

Frequent: fever and non-specific symptoms (irritability, headache, malaise), CNS shunt malfunction.

2.

Uncommon: local suppuration or cellulitis at insertion site, abdominal complaints (localized pain, distention).

3. B.

Rare: seizures.

The clinical manifestations of infections associated with intravascular catheters include: 1.

Frequent: fever (the hallmark of intravascular infection).

2.

Common: catheter dysfunction.

3.

Uncommon: insertion site suppuration or cellulitis; embolic phenomena (retina, skin, etc.).

4.

Rare: organ dysfunction due to immune complex deposition (ie, nephritis).

C.

The clinical manifestations of infections associated with urinary catheters are: 1.

Frequently asymptomatic.

2.

Uncommon: dysuria, urgency, frequency, enuresis, or cloudy urine.

3.

Fever if upper tract infection or this is the origin of hematogenous dissemination.

D.

The following are useful in confirming the diagnosis of CNS catheter infection:

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1.

Examination and culture of ventricular fluid (pleocytosis may be lacking; normal WBC in 17-35% of children; elevated protein; glucose usually normal).

2.

Blood culture (usually sterile unless VA shunt).

3.

Culture of suppurative material at insertion site or in wound (if present).

4. E.

Abdominal ultrasonography if pseudocyst suspected.

The following are useful in confirming the diagnosis of intravascular catheter infection: 1.

Blood cultures (peripheral and through each port of the catheter).

2.

Quantitative culture of catheter tip (>15 colonies on rolled agar surface).

F.

3.

Ultrasonography if thrombosis or endocarditis suspected.

4.

Direct straining of blood from catheter EM of catheter tip.

The diagnosis of urinary catheter infection is defined as: 1.

Isolation of a pathogen from urine (> 103 cfu/ml) (may need to be confirmed by repeat culture). Note: Pyuria is uncommon.

G.

The etiologic agents associated with CNS catheter infections are: 1.

Frequent: Coagulase-negative staphylococci (~70%); Staphylococcus aureus (-20%) (pathogenesis: inoculation at insertion or manipulation).

2.

Uncommon: other skin flora; gram-negative enteric bacilli or

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anaerobes (if abdominal symptoms). 3.

Rare: age-specific hematogenous pathogens (S. pneumoniae, N. meningitidis, GBS).

H.

Etiologic agents to be considered in patients with intravascular catheter infections include: 1.

Frequent: coagulose-negative Staphylococcus aureus, C. albicans.

2.

Common: Enteric rods, P. aeruginosa, and other gram-negative bacilli, Enterococcus, and Candida spp.

3.

Occasional: Bacillus spp., atypical mycobacteria, and other commensals.

I.

The etiologic agents in patients with urinary catheter infections include: 1.

Frequent: gram-negative enteric rods (pathogenesis: inoculation at insertion with endogenous perineal flora).

2.

Common: Pseudomonas aeruginosa, Serratia marcescens, other nosocomial gram negatives, Enterococcus, Candida albicans or other Candida species (pathogenesis: inoculation at insertion with endogenous perineal flora often "created" by gut overgrowth).

J.

The principles of management of catheter-related infections are: 1.

In a febrile patient with an indwelling catheter always suspect

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catheter-related infection. 2.

Malfunction of the catheter should be attributed to infection unless proved otherwise.

3.

Repeated cultures are essential to guide therapy.

4.

Catheter removal is the optimal method to cure the infection, usually with antimicrobial therapy.

5. K.

Antibiotic therapy without catheter removal is sometimes curative.

The specific methods useful in managing CNS catheter infections include: 1.

Appropriate initial antimicrobial therapy (vancomycin) (add a third generation cephalosporin or expanded spectrum penicillin if abdominal symptoms).

2.

Repeated CSF cultures to ensure cure or control of infection.

3.

Refine antimicrobial therapy depending upon agent, susceptibility, and clinical and microbiologic response.

4.

Remove CNS device immediately if: (1) it is no longer needed or doesn't work, (2) there is suppuration at the insertion site, (3) infection is caused by yeast, atypical mycobacteria, or is polymicrobial, or (4) CSF cultures do not sterilize promptly.

5.

Continue treatment for 7 to 10 sterile CSF culture days before replacing device.

L.

The specific methods useful in managing intravascular catheter

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infections include: 1.

Exit site infection: catheter removal and local care.

2.

Subcutaneous tunnel infection: catheter must be removed and antibiotic therapy is given.

3.

Catheter-related sepsis: catheter removal ideal but often not practical.

4.

In-situ therapy: (1) initiate appropriate antimicrobial(s) (vancomycin often with aminoglycoside or a third generation cephalosporin), (2) daily blood cultures (should be sterile within 3-4 days or catheter removal is indicated),(3) refine antimicrobial agent based on identification and susceptibility results.

5.

Indications for immediate intravascular catheter removal: (1) ongoing sepsis, (2) endocarditis, (3) isolation of yeast or atypical mycobacteria,(4) isolation of Pseudomonas aeruginosa or other gram-negative bacilli in neutropenic patients, (4) failure of in-situ therapy.

6.

Duration of therapy:

Prompt resolution and catheter removal

- 3 to 5 days. S.aureus and gram negative bacilli - 14 days minimum. In-situ therapy - 7 to 10 days after sterilization of blood. M.

The specific methods useful in managing urinary catheter infections include:

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1.

Removal (replacement) of the catheter, if possible.

2.

If removal is not possible, if infection doesn't resolves spontaneously, or if there is clinical evidence of ascending infection, initiate appropriate antimicrobial therapy (optimal duration?).

N.

Specific methods that may prevent CNS catheter infections: 1.

Good surgical technique.

2.

Antibiotic prophylaxis limited to immediate pre- and postoperative periods.

3. O.

Optimal prophylaxis regimen not defined

Specific methods that might prevent intravascular device infections include: 1.

Optimal sterile technique at insertion.

2.

Optimal catheter care (minimize manipulation, avoid transparent dressings, specialized care team, handwashing, replace IV delivery systems every 48-72 hours, prepare hub prior to injection or aspiration, minimize use of stopcock).

P.

3.

Catheter design (skin tunnel, cuff, disinfectant coated).

4.

Remove catheter as soon as possible.

Specific methods to prevent urinary catheter infection include: 1.

Aseptic technique during insertion.

2.

Removal of catheter as soon as possible.

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3.

Optimal catheter care (handwashing, closed system, minimizing entry into system, good drainage to avoid urine reflux).

4.

Avoid urethral meatal care and minimize perineal care (avoid catheter manipulation).

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