Pathogenesis of bacterial infection and nosocomial infection

PATHOGENESIS OF BACTERIAL INFECTION AND NOSOCOMIAL

INFECTION

Regi Septian

IntroductionInfection Identification of microorganisms

in host tissue or the blood stream, and an inflammatory response to their presence.

Pathogenesis mechanism of infection and to the mechanism by which disease develops.

Host DefensesHost possesses several layers of endogenous

defense mechanism prevent microbial invasion, limit proliferation of microbes within the host, and contain or eradicate invading microbes.

Skin physical barrier.Mucus + cilia trapping and clearing

respiratory tractGastric acid kills bacteriaMacrophages, complements, immunoglobulin inflammatory response activation

Host DefensesThe magnitude of the response and eventual

outcome generally are related to several factors: (a) the initial number of microbes(b) the rate of microbial proliferation in relation to

containment and killing by host defenses(c) microbial virulence(d) the potency of host defenses. drugs or disease states that diminish any or multiple components of host defenses are associated with higher rates and potentially more grave infections.

EtiologyBacteria, Fungi, Virus

Bacteria:Major etiology of surgical infections.Gram (+) aerobic skin commensals (Staphylococcus

aureus and epidermidis and Streptococcus pyogenes) and enteric organisms such as E. faecalis and faecium

Aerobic skin commensals cause a large percentage of surgical site infections

Enterococci can cause nosocomial infections [urinary tract infections (UTIs) and bacteremia] in immunocompromised or chronically ill patients, but are of relatively low virulence in healthy individuals

BacteriaGram (-) E. coli, Klebsiella pneumoniae,

Serratia marcescens, and Enterobacter, Citrobacter, and Acinetobacter spp.

Anaerobic organism unable to grow or divide poorly in air, as most do not possess the enzyme catalase, which allows for metabolism of reactive oxygen species.

FungiFungi of relevance to surgeons include those

that cause nosocomial infections in surgical patients as part of polymicrobial infections or fungemia (e.g., C. albicans and related species), rare causes of aggressive soft tissue infections (e.g., Mucor, Rhizopus, and Absidia spp.), and so-called opportunistic pathogens that cause infection in the immunocompromised host (e.g., Aspergillus fumigatus, niger, terreus, and other spp., Blastomyces dermatitidis, Coccidioides immitis, and Cryptococcus neoformans).

VirusMost viral infections in surgical patients occur

in the immunocompromised host, particularly those receiving immunosuppression to prevent rejection of a solid organ allograft.

Relevant viruses include adenoviruses, cytomegalovirus, Epstein-Barr virus, herpes simplex virus, and varicella-zoster virus.

Surgeons must be aware of the manifestations of hepatitis B and C virus, as well as HIV infections, including their capacity to be transmitted to health care workers

Nosocomial InfectionInfections that are acquired in hospital (48

hours or more after admission)

SSI (Surgical Site Infection)UTI (Urinary Tract Infection)PneumoniaBacteremia

SSI (Surgical Site Infection)Infections of the tissues, organs, or spaces

exposed by surgeons during performance of an invasive procedure

Classification :Incisional Infections

- Superficial- Deep

Organ/Space infections

Factors related to SSI develoment :The degree of microbial contaminationThe duration of the procedureHost factors (diabetes, malnutrition, obesity,

etc.)

UTI (Urinary Tract Infection)Prolonged use of folley catheter for purpose

of urinary drainageCulture results : > 104 CFU/mL of microbes Postoperative surgical patients should have

urinary catheters removed as quickly as possible, typically within 1 to 2 days, as long as they are mobile.

Hospital Acquired PneumoniaProlonged use of ventilation tubesDiagnosis should be made using the presence

of a purulent sputum, elevated leukocyte count, fever, and new chest x-ray abnormality

Surgical patients should be weaned from mechanical ventilation as soon as feasible, based on oxygenation and inspiratory effort.

BacteremiaProlonged use of venous or arterial accessMany patients who develop intravascular

catheter infections are asymptomatic, often exhibiting an elevation in the blood WBC count.

Routine, scheduled catheter changes are associated with slightly lower rates of infection

4 Important FactorsThe hostThe microbesThe environmentTreatment

The HostPeople in hospital are already sickPoor general resistance to infectionLack of immunity age,

immunocompromisedReduced immunity diabetes, severe burnsPoor local resistance poor blood supply to

tissuesSurgery wound, suturesMedical devices catheters, prostheses,

tubing

The MicrobesNosocomial infections are often caused by

opportunistic pathogens those which do not normally cause infection in healthy people

May be a reflection of reduced defences of host or access to sites not normally colonised by organisms

May be from normal flora or environment

Opportunistic PathogensPseudomonas aeruginosaStaphylococciE. coli and other coliformsStreptococci and EnterococciBacteriodes fragilisCandida albicansHerpes simplex virusCytomegalovirus

The EnvironmentOwn normal flora (endogenous)Infected patientsTraffic of staff and visitorsBlood productsSurgical instruments

Prevention and TreatmentProphylaxis Maneuvers to diminish the

presence of exogenous (surgeon and operating room environment) and endogenous (patient) microbes

General Principles:Minimalize microflora entering the surgical

site:Gloves, gownAseptic and antisepticHair removal before the procedure

Source ControlThe primary precept of surgical infectious disease therapy

consists of drainage of all purulent material, débridement of all infected, devitalized tissue, and debris, and/or removal of foreign bodies at the site of infection, plus remediation of the underlying cause of infection

An ongoing source of contamination (e.g., bowel perforation) or the presence of an aggressive, rapidly-spreading infection (e.g., necrotizing soft tissue infection) invariably requires expedient, aggressive operative intervention, both to remove contaminated material and infected tissue (e.g., radical débridement or amputation) and to remove the initial cause of infection (e.g., bowel resection).

5 Pillars of Infection ControlIsolation and barrier precautionsDecontamination of equipmentPrudent use of antibioticsHand washingDecontamination of environment

Thank You

Harap menambahkan tentang agent infeksi: flora normal, penghasil toksin, etc

Perbedaan kolonisasi dan infeksiInfeksi jamur: dermatophyte? Saprophyte?

Mukor?