Nosocomial Infections

Nosocomial infections also known as hospital acquired infections are infections not present and without evidence of incubation at the time of admission to a healthcare setting. They become evident 48 hours after admission or 48 hours after patient is discharged.

Definition of nosocomial infections

• NI - not an infection contracted by health care personnel in the course of their profession - professional infection.
• Basic feature of NI - hospital strains have higher resistance to antimicrobials and disinfection.
• Cause of higher morbidity and mortality.

Classification of nosocomial infections

By agent:

• Exogenous - the agent is introduced into the organism from outside;
• endogenous - own infectious agent from the colonized site into another system, into a wound, into serosal cavities (Blood, during surgery, invasive procedures, immunosuppressive treatment); the etiologic agent is the microflora present in the body, which is normally non-pathogenic.

According to the epidemiological point of view:

• non-specific - reflect the epidemiological situation in the catchment area of the health facility or are an indicator of the hygiene level of the facility;
• specific - a consequence of diagnostic and therapeutic procedures, their occurrence can be influenced by asepsis, sterilization, disinfection, hygiene-epidemiological regime.

According to the affected system:

• respiratory;
• catheter - from the bloodstream;
• urinary tract infections;
• gastrointestinal;
• wound infections;
• genital tract;

Process of spreading nosocomial infections

• Existence of a source of the causative agent - Transmission of the causative agent by NI - Presence of a susceptible individual - Transmission of the causative agent by NI - Presence of a susceptible individual.

Source - Nosocomial agent

• Patient - his own microflora, another patient (his microflora is in saliva, on hands, in air, dust, tools, etc.).
• Health care worker - does not appreciate his own disease.
• Visitor - least serious source, control of visitors.

Forms of nosocomial infections

• Manifest - less dangerous, easily diagnosed and treatable.
• Carriage - carriers harbor and excrete infectious agents without obvious signs of disease.

Nosocomial transmission

• Direct transmission:
  • presence of a source of infection and a susceptible individual;
  • contact (e.g., kissing/sexual contact);
  • essentially transmission by the hands of health care personnel;
  • in newborns - eye infection (direct contact with the mucous membrane of the vagina);
  • droplet infection;
  • alimentary route - preparation of milk food in the neonatal unit.
• Indirect transmission depends on:
  • the ability of the microorganism to survive outside the host body;
  • the existence of a suitable medium in which the aetiological agent multiplies and with the help of which the infection is transmitted.

Most common bacterial agents of nosocomial infections

• Staphylococcus,
• Enterococcus,
• Streptococcus pneumoniae,
• Clostridium difficile,
• Enterobacteriaceae,
• Pseudomonas aeruginosa,
• Helicobacter pylori,
• Mycobacterium species,
• mycotic agents.

Mechanism of bacterial resistance

• ATBs have been used for more than 50 years.
• ATBs are a substantial part of all drug costs.
• Adequate application of ATBs - economics and spread of resistance.
• Emergence of resistance - most in ICU and ARO settings - multiple ATB applications.

Most important microorganisms: gram-positive bacteria

• MRSA - methicillin-resistant Staphylococcus aureus.
• MRCNS - methicillin-resistant coagulase-negative staphylococcus aureus.
• VISA - Staphylococcus aureus with reduced susceptibility to vancomycin.
• PRSP - Streptococcus pneumoniae resistant to PNC.
• VRE - vancomycin-resistant enterococci.
• Enterococci with high resistance to aminoglycosides.

Most important microorganisms: gram-negative bacteria

• With production of broad-spectrum β-lactamases encoded plasmidally and chromosomally (ESBL).
• With resistance to carbapenems.
• With resistance to fluoroquinolones.
• With resistance to aminoglycosides.

Resistant strains of MRSA

• Identified in 1961.
• In the US, incidence increased from 2.4% in 1975 to 30-60% after 1990.
• Scandinavia - still 1% in 1990.
• Spain and France - more than 30%.
• 1990 in Central Europe - prevalence from 1.7% to 8.7%'.
• England - from 3% in 1989 to 34% in 1998.
• Measures - isolation and compliance with a hygiene and epidemiological regime, including hand washing.

MRSA resistance in the Czech Republic

• Exact figures are not available;
• 70 hospitals have investigated invasive isolates under the EARSS (European Antimicrobial Resistance Surveillance System) project;
• MRSA incidence - 3.8% in 2000 increased to 8.8% in 2004.

Resistance is caused by

• The production of bacterial enzymes that disrupt or modify the structure of the ATB;
• Alteration of the bacterial wall - reduction of its permeability;
• modification of the target sites of ATBs;
• increased excretion of ATB from bacterial cells to prevent its intracellular accumulation.

Suppression of nosocomial infections

• Knowledge of all data and information on the emergence and spread of NN is a prerequisite;
• Data collection is integrated into the "Surveillance" programme;
• Decree 195/2005 Coll. - lists infectious diseases for which isolation in inpatient facilities is ordered and treatment is mandatory;
• Act on the Protection of Public Health and on Amendments to Certain Related Acts - 258/2000 Coll., last amended - Act No. 274/2003 Coll.

Repressive measures

• Tasks:
  • eradication of an outbreak of an already established disease;
  • reporting of an outbreak of NI;
  • treatment of a patient with NI, isolation;
  • barrier nursing care;
  • search for contacts and source of infection;
  • disinfection - in the outbreak area;
  • increasing the immunity of susceptible patients;
  • control of the measures ordered, including thorough documentation.

Nosocomial urinary tract infections

• Account for 30-40% of UTIs;
• 60-90% - association with indwelling urinary catheter;
• 10% - urological-endoscopic intervention;
• Less costly NI, but prolonged hospitalization increases cost of treatment.

Prevention

• Always use a sterile catheter;
• thorough disinfection of the periurethral area;
• hand disinfection, use of sterile gloves;
• catheter fixation - prevention of movement in the urethra.

Surgical site infection

• Third most common NI - 14-20% CDC:

• • superficial IMCHV;
  • deep incisional IMCHV;
  • Organ/space IMCHV.

Clinical picture of IMCHV

• Redness,
• serous secretions;
• purulent secretion from a small area of the wound;
• purulent secretion from the whole wound area, eventually its disintegration - dehiscence.

Prevention in the preoperative period

• The shortest possible hospitalization before surgery;
• Thorough bath and shower;
• for elective procedures, overtreat other infections;
• attention to shaving the surgical site;
• antibiotic prophylaxis.

Intraoperative prophylaxis

• Principles of asepsis and barrier nursing techniques;
• use of protective equipment by theatre staff;
• disposable drapes;
• disinfection of the surgical field site with proper exposure to disinfectant;
• precise surgical technique;
• minimizing the number of staff in the operating room;
• efficient ventilation and air conditioning in the operating room.

Postoperative interventions

• Cover the incision with a sterile dressing for 24-48 hours;
• principles of asepsis during dressings;
• Educate family and patient about proper wound care and symptoms of wound infection.

Respiratory tract - pneumonia

• 10-20% of all nosocomial infections;
• incidence in ICUs can be as high as 65% with mortality rate above 25%;
• prolong hospitalization;
• persons at risk are over 70 years of age.

Specific risk factors

• Internal- age, smoking, alcoholism, malnutrition, obesity, lung disease, severe general illness, and microbial flora of the oropharynx.
• External - length of hospitalization, immunosuppression, drug administration, thoracic and abdominal surgery, tracheotomy, ET, bronchoscopy, ventilators, nebulizers.

General principles of prevention

• maintaining proper personal hygiene and hand washing
• sterilisation of hospital equipment
• providing clean and sanitary environment
• existence of infection control team
• regular, close observation of high-risk units .e.g intensive care
• development of policies on areas such as isolation, disinfection and antibiotic usage

Links

Sources

• KOLEKTIV AUTORŮ,. Základy ošetřování nemocných. 1. vydání. Praha : Karolinum, 2005. 145 s. ISBN 80-246-0845-6.

• MIKŠOVÁ, Z, et al. Kapitoly z ošetřovatelské péče I.. 2. vydání. Praha : Grada, 2006. 248 s. ISBN 80-247-1442-6.

• MIKŠOVÁ, Z, et al. Kapitoly z ošetřovatelské péče II.. 2. vydání. Praha : Grada, 2006. 171 s. ISBN 80-247-1443-4.

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• WORKMAN, B a C., L. BENNETT. Klíčové dovednosti sester. 1. vydání. Praha : Grada, 2006. 259 s. ISBN 80-247-1714-X.
• MANDAL, BK. Lecture Notes : Infectious Diseases. 6th edition. Wiley-Blackwell, 2004. 280 pp. ISBN 978-1-4051-0820-1.