HOSPITAL CROSS-INFECTION

Definition Cross-infection: infection that spreads from person to person. Auto-infection : is derived from the patient himself.

Types of Infection in Hospitals Infection contracted & developing outside hospital & requiring admission to hospital ( pneumonia ) Infection contracted outside hospital & becoming clinically apparent in hospital ( measles ) Infection contracted & developing inside hospital (wound infection) Infection contracted in hospital but becoming clinically apparent after discharge ( typhoid fever )

Endogenous Infections The infecting organism is derived from the patient (U.T.I. & pulmonary infections in recumbent patients ) The bacteriological detection of such infections by blood culture is needed in major cardiac surgery or transplantation.

Exogenous infections Acquired from other patients or from staff carriers (nurses, doctors, medical students) The organisms causing such infections are usually highly infectious & very resistant to many drugs.

Mechanisms of transmission of exogenous infections Direct contact with : fomites, contaminated instruments, etc. Air-borne dust & droplets. Contaminated food & eating utensils.

Surgical wound infections More frequent in emergency operations where infected tissue is likely . Lowest in special surgical units (orthopedic & cardiac units) where elective surgery is done.

Surgical infections may be: Endogenous: ( transfer of Staph.. or Strep.via patient nose, or coliform bacilli via bowel ) during operation. Exogenous, derived from other patients, healthy staff carriers, visitors, etc. We differentiate between infection occurring during an operation or post-operatively by site & extent of infection & the time firstly recognized.

Surgical wound infections may be divided into : Infection contracted in theatre during operation. Infection contracted in wards after operation.

Theatre Wound Infections Apparent within 3 days following the operation. It depends on : Virulence of infecting organism. Depth & size of wound. Duration of operation. Presence of drainage tubes. Normal flora of site. Patient age. Late localized symptoms & signs, suggest a deep, seated abscess .

Sources of theatre infection Healthy staff carriers. Unsterile textile Unsterile instruments. Air - borne theatre dust. Faulty dressing technique. Faulty theatre design.

Theatre Wounds : Modes of Transmission Surgeons hands through minute holes in gloves, or dripping of sweat on the wound. An apparatus near the wound, e.g: operation lamps or portable x-ray machine. Bacteria in laden particles of theatre air

Ward Wound Infection Predisposal factors are: Appears from the 4th day after operation. Predisposal factors are: Blood or serum seeping through drainage tubes soaking dressings Lengthy procedures (evacuation a blood clot formed in the ward ) Loose dressings Burns dressings

Cont. Factors causing cross-infection Too frequent dressings. Insufficient facilities for aseptic techniques. Shortage of staff ( delay in dressings before rounds or visits) Rapid inspection of wounds by surgeons without full re-dressing

Investigation of Hospital Wound Infections Isolate & type the infecting organism. Determine whether it is a theatre or ward infection. Swab patient nose & throat to look for an endogenous infection. Swab noses of staff & patients to determine source of infection if organisms isolated are similar. If not similar it is a waste of time to search for carriers.

Organisms Causing Hospital Infection Staph. aureus: *Commonest cause of wound infections. *Phage typing determines the strain causing infection. *Reservoir is the anterior nares, transferred by direct & indirect contact.

Staph. infections are: Wound infections . Boils,pemphigus neonatorum, carbuncles. Enterocolitis. Pneumonia. Breast abscess. U.T.I.

Strept. pyogenes: Reservoir is the throat, transferred by close direct contact ( will not survive long on skin) Gram negative intestinal bacilli: E.coli, Proteus vulgaris, Pseudomonas & Klebsiella. *Cause wound infection by auto-infection. *The anterior urethra is colonized by E.coli, Pr. vulgaris & E. fecalis.

Cont. *Bacteria can be driven into bladder during catheterization ( cystitis ) *Urinary infection due to Pseudomonas is carried by hands of attendants from urine bottles to bladder drainage apparatus *In other coliform wound infections the source of infection is septic wounds, e.g: fecal fistulae & colostomies.

Clostridia: @Reservoir is feces of man, animals , soil. @Harmless if anaerobic atmosphere is unavailable. @It causes gas gangrene @Factors predisposing to infections are:- * Faulty sterilization of dressings & ligatures. * Excessive damage of tissue. * Sepsis of wounds by other organisms.

Prevention & Control of Hospital Cross-Infections Asepsis measures: Aseptic techniques. Proper sterilization Strict “No Touch” techniques. Strict personal hygiene. Health education ( patients, nurses,other staff ) Use of disinfectants in localized sites.

b) Isolation facilities: Cubicles & single-bedded rooms , needed for carriers & high-risk patients ( extensive skin grafting & burns patients ) c) Invasive procedures : Care should be taken with cannulation, catheterization, anaethetic machines, respirators etc.

d) Personnel : *Staff with respiratory or surface infections should be prevented from nursing, treating or cutting patients. *In theatre, surgical staff must be properly gowned, masked & capped. *Thorough scrubbing & glove wearing should be a habit whenever touching a wound even in the ward . *Auxulary staff , eg: catering and household-staff should be screened to detect carriers & give treatment .

e) Ward & theatre design : *Wards should be designed with adequate space & proper ventilation. *Theatres should be separated from wards. *Accessory rooms should be separate. *Ventilation should be monitored with a positive pressure system & air should be filtered.

f) Antibiotic policy : *Antibiotics must be used with care. *Abuse may lead to production of drug resistance & multiplication of resistant organisms. *The use of wide-spectrum antibiotics as a pre-medication in bowel surgery is not important ; enema has got the same advantage. *The use of prophylactic antibiotics must be stopped to avoid emergence of resistant bacteria.

Cont. @Treatment of surgical wounds in theatre by irrigation , spraying & dusting has proved ineffective in preventing wound infections. @Adoption of a rotational antibiotic policy using different sets of antibiotics for successive periods is the best way to control hospital infections & prevent drug resistance.

g) Staff conduct : Careful cleansing & disinfection of operation site. Careful use of sterile materials & instruments. Gentle handling of tissues to avoid damage that may reduce their resistance to bacteria.

Record keeping: To detect source of infection & to point where preventive measures had been broken, we should record and register in details the:- Nature of operation. Staff involved in theatre & ward. State of wound each time dressed. The site, nature & extent of any infection arising in the wound.

i) Administration: The clinical bacteriologist should supervise services in the ward & theatre. He must be included as a member in administration of concerned hospital units e.g.: theatre , pharmacy, wards, sterilization , etc.