Guidelines on Prevention and Control of Hospital Associated Infections

Prevention of Hospital Associated Infections(Contd.)

Ventilation requirements for operation rooms Mechanical ventilation with air conditioning providing filtered air. 

     At least 15 air changes per hour at 22° C are recommended.

     Filters and air flow should be checked regularly.

     In some hospitals, window air conditioners are in use. These air conditioners require proper maintenance and do not guarantee air quality.

Theatre clothing

     Persons working in the operating rooms must wear clean surgical attire in place of their ordinary clothing.

     Surgical attire should be designed for maximum skin coverage; shedding of skin scales is a potential source of contamination.

     Operating theatre shoes should be washable and impervious.

     Head and facial hair should be covered.

     Personnel should wear disposable deflector masks.

     The surgical team should wear sterile gowns and gloves. A plastic apron should be worn under the sterile gown.

     Double gloving is used for protection of the team in operations on HIV, HBV or HCV positive patients. Double gloving is also used for implant surgery.

Surgical handscrub

     4% chlorhexidine or 10% povidone-iodine should be used for skin disinfection.

     Scrubbing for two minutes is as effective as scrubbing for 10 minutes.

Preparation of the surgical site

     The patient’s skin at the site of incision as well as a wide margin should be prepared with 10% povidone iodine, or 4% chlorhexidine. These should be allowed to dry before making the incision.

     The skin should be covered by impervious drapes or with sufficient thickness of pervious material to prevent fluid penetration during the surgery.

Personnel

     Unnecessary conversation and movement should be restricted.

     The number of personnel in the operation theatre should be restricted to the minimum necessary for the procedure.

Surgical procedure

     Wounds should not be drained unless absolutely necessary. A closed system of drainage should be used in cases where a drain is essential.

     The technique of surgery should ensure minimum tissue trauma for the patient.

1.      Perioperative chemoprophylaxis in surgery

Perioperative chemoprophylaxis is an essential adjunct to many surgical procedures. For some operations, there is inevitable contamination of the surgical wound following opening of a hollow viscus such as the gastrointestinal tract or the incisions through mucous membranes with a rich normal microbial flora such as the mouth, oesophagus and vagina. In other operations, the use of implants as in cardiac valve prostheses or artificial joints increases the risk of persistence of normal skin flora at the prosthetic site. In such procedures, perioperative chemoprophylaxis reduces the incidence of hospital-associated infections.

Peri-operative antimicrobial chemoprophylaxis is to be given with induction of anaesthesia and continued for not more than 24 hours. The choice, dosage and duration of antimicrobial chemoprophylaxis are important.

Choice of antimicrobial for chemoprophylaxis

The organisms involved in surgical operations are usually derived from the normal flora and are sensitive to many antibiotics. Patients admitted to hospital and operated as emergencies such as acute abdominal emergency or trauma are not colonized with multi-drug resistant hospital flora. Patients admitted within 24 hours of an elective operation are not colonized with hospital flora. Patients having repeated surgery and after antibiotic therapy are often colonized with antibiotic resistant bacteria in the gastro-intestinal tract (Klebsiella sp, Pseudomonas sp, etc.) or the skin (methicillin-resistant coagulase-negative staphylococci, Acinetobacter sp.) or mouth (Candida sp.).

The choice of antibiotics for these patients depend on the endogenous flora likely to cause the infection.

When to start; when to stop

Start of chemoprophylaxis: Given with induction of anaesthesia and second dose may be given in prolonged surgeries lasting more than three hours.

Stopping chemoprophylaxis: One or two doses only are given

     Hospital associated respiratory infections

Nosocomial pneumonia is one of the most serious hospital associated infections.

Definition: Nosocomial pneumonia is defined as a lower respiratory tract infection that appears during or after hospitalization of the patient who was not incubating the infection on admission to hospital.

The diagnostic criteria are:

     Fever, cough, development of purulent sputum;

     Radiological changes showing progressive infiltration, and

     Sputum Gram-stain showing >25 WBCs per low field and bacteria.

Specimen: sputum, tracheal aspirate or bronchoscopic aspirate are often cultured.

Results of culture should be interpreted in the light of clinical findings. In patients with tracheostomy, the presence of some WBCs does not necessarily imply pneumonia.

Positive cultures, especially those obtained from patients who are intubated, do not necessarily mean pneumonia.

Colonisation of the respiratory tract with multi-resistant hospital bacteria is very common in patients on broad spectrum antibiotics, receiving mechanical ventilation or following surgery. This can occur within the first 24 hours in a critical care unit.

Respiratory secretions should be disposed in a safe way i.e. treatment with sodium hypochlorite, incineration or autoclaving. Linen and waste should be treated as infected.

Nosocomial respiratory tract infections may occur in several different patient groups. In some cases such as hospital-acquired infection with Legionella, the hospital environment may play a significant role.

Colonization of mouth and respiratory passages by hospital bacteria

Multidrug resistant gram negative rods and MRSA can be acquired during tracheal toilet. Sometimes colonization progresses to pneumonia. The clinical outcome of positive cultures from the trachea should be carefully assessed before deciding to start therapy. Patients on broad-spectrum antibiotics may suffer replacement of the normal oral flora by resistant gram-negative rods. This is usually contamination, not infection.

Prevention of aspiration pneumonia in hospital

     Comatose patients must be positioned on their side to limit the potential for aspiration.

     Oral feeds should be avoided in patients with neurological or swallowing abnormalities.

     Medications which impair consciousness (sedatives, narcotics) must be limited.

Prevention of pneumonia after surgical procedures

     All invasive devices used during anaesthesia must be sterile. 

     Anaesthetists must use gloves and mask when undertaking invasive tracheal care.

     Disposable filters (for individual use) for endotracheal intubation effectively prevent the transmission of micro-organisms among patients by ventilators.

     Preoperative physiotherapy helps to prevent nosocomial pneumonia in patients with chronic respiratory disease.

     Urinary tract infections

Urinary tract infections are the most frequent nosocomial infections. The great majority of these infections are associated with an indwelling urethral catheter.

Definition: An infection of the urinary tract that was not incubating at the time of admission.

The diagnostic criteria are:

     Clinical symptoms of fever, suprapubic tenderness, frequency and dysuria.

     Presence of bacteria in the urine in significant quantity, i.e. more than 105 per ml.

Specimen for culture: Urine should be collected aseptically for culture by needle aspiration from the catheter. Catheter tips and specimens from urine bags are generally unsuitable for culture because the results are hard to interpret.

     Intravascular catheter related infections

Definitions:

     Exit site infections: Infections with erythema, tenderness, induration or purulence within 2 cm of the skin at the exit site of the catheter. These are commonly caused by Staph. aureus and coagulase-negative staphylococci.

     Bloodstream infections may follow colonization of peripheral or central venous line catheters. Growth of >15 (semi-quantitative) or >103 (quantitative) CFU from a catheter segment in the absence of accompanying clinical symptoms signifies colonization. Likely organisms include: Staph aureus, coagulase-negative staphylococci, Candida sp. and diphtheroids (CDC JK group).

     Contaminated infusions can lead to bacteraemia or systemic infection and are mainly caused by gram negative rods. Infusate and intravascular medications can cause primary blood stream infection if they are contaminated. Aseptic technique in preparation of infusate and of single unit dose IV medications are highly recommended.

Key practices for all vascular catheters include:

     Avoiding indwelling intravenous catheterization unless there is a medical indication;

     Limiting the use of catheters to as short a duration as possible; 

     Preparing fluids aseptically and immediately before use, and

     Training of personnel in catheter insertion and care

Peripheral Vascular Catheters

     Short peripheral venous catheters are not usually associated with infections.

     There is no significant difference in infection rates amongst the various types of catheter materials.

     A high level of aseptic technique should be used for insertion and handling of catheters.

     Hands must be washed before all catheter care, using hygienic hand wash or rub. 

     Skin at the insertion site must be washed and disinfected with an antiseptic solution. 

     A dressing change is not normally necessary, unless it is visibly soiled.

     If local infection or phlebitis occurs, the catheter should be removed or re-sited immediately.

     Intravenous lines need not be changed more frequently than catheters themselves, except after the transfusion of blood or intralipids, and for discontinuous perfusions. 

Central Vascular Catheters

     Mask, cap, sterile gloves and gown must be worn for insertion. 

     Sterile gauze or transparent dressing should be used to cover the catheter site.

     A surgical hand wash or rub is required before insertion of the catheter and the subsequent catheter dressings. 

     The dressing should be changed at the time of the change of lines, using surgical asepsis techniques.

Antimicrobial impregnated central venous catheters are associated with fewer line infections. Devices incorporating silver sulphadiazine or chlorhexidine-silver sulphadiazine are less likely to promote emergence of resistance than antibiotic impregnated catheters. However, careful evaluation of these devices is needed to determine the relative benefits of reduction of infections compared with the future risk of antimicrobial resistance.