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 &beta;-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