**2.1. The high risk areas for HAI**

Nurseries, Intensive care units (ICUs), Operation theatres (OTs) and Post operative wards, Labour room, Dialysis unit, Organ transplant unit, Oncology wards, Burn units, High Dependency units (HDU) etc are mainly high risk areas for HAI.

Contact transmission : The organisms which are transmitted by contact are MRSA, VRE etc. Direct contact transmission occurs direct body surface to body surface contact and commonly occurs to HCW [16], while giving patient care. Indirect contact transmission occurs with contaminated inanimate objects e.g. needles, dressings, contaminated hands of HCW, endo‐

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Droplets are generated while coughing, sneezing, talking or performing suctioning, broncho‐ scopy etc. The droplets (large particles >5μm in size) transmitted from infected person through air (short distance ≤ 3 feet) and deposited on host's conjunctiva, nasal mucosa or mouth. But

Airborne transmission occurs by airborne droplet nuclei (small particle ≤ 5 μm in size) which are evaporated droplets containing the microorganisms that remain suspended in air for few hours or days. Mycobacterium tuberculosis, Varicella, Rubella, Influenza viruses etc can be

The organisms causing HAI are mostly antibiotic resistant, which adds to the increased

Specially Extended spectrum β – lactamase (ESBL producing) or multi / Extreme drug Resistant

**•** Enterobacteriaceae : Klebsiella pneumoniae, E.coli, Citrobacter sp., Enterobacter sp. etc.

**•** Burkholderia species, Stenotrophomonas maltophila and amongst fungi especially Fluco‐ nazole resistant Candida species are also becoming important agents causing HAI specially

scopes etc.

the droplets are not suspended in air [15].

transmitted by droplet nuclei [15].

morbidity and mortality of patients.

**•** Major Gram positive pathogens

**•** Penicillin Resistant Pneumococci **•** Major Gram negative pathogens :

Gram negative bacteria e.g. **•** Pseudomonas aeruginosa

**•** Acinetobacter baumani

in ICU patients [17].

**•** Vancomycin Resistant Enterococci (VRE)

**•** Antibiotic resistant pathogens associated with HAI are –

**•** Methicillin Resistant Staphylococcus aureus (MRSA)

**•** Vancomycin Resistant Staphylococcus aureus (VRSA) **•** Vancomycin Intermediate Staphylococcus aureus (VISA)

**•** Penicillinase producing Neisseria gonorrhoeae (PPNG)

**•** Methicillin Resistant Coagulase negative Staphylococci (MRCONS)

**2.5. Infecting agents**

#### **2.2. Host factors responsible for HAI**


#### **2.3. Source of HAI**

HAIs acquired by a patient may be endogenous (autogenous) and exogenous. Endogenous infections are caused by patient's own flora or by carrier state, whereas exogenous infections result from transmission of organisms from various sources via different routes [15]. Exoge‐ nous sources may be other patients with infectious diseases. HCWs carrying MRSA, Multidrug resistant (MDR) Gram negative organisms on hands or dresses, contaminated disinfectant solutions, environmental surfaces especially frequently – touched surfaces e.g. bed rails, furnitures, door latches, toilet seats, telephones etc and even floor, window panes, air condi‐ tioners, renovation work, inefficient sterilization of equipment and devices. Moreover, medications or devices, necessary to cure patient's primary medical condition can also predispose to HAI. The important ones are -


#### **2.4. The mode of transmission of HAI may be**

Contact (direct or indirect), droplet, airborne, common vehicle (food, water, medical devices, blood or blood products etc) and vector borne (mosquitos, flies, rats etc)

Contact transmission : The organisms which are transmitted by contact are MRSA, VRE etc.

Direct contact transmission occurs direct body surface to body surface contact and commonly occurs to HCW [16], while giving patient care. Indirect contact transmission occurs with contaminated inanimate objects e.g. needles, dressings, contaminated hands of HCW, endo‐ scopes etc.

Droplets are generated while coughing, sneezing, talking or performing suctioning, broncho‐ scopy etc. The droplets (large particles >5μm in size) transmitted from infected person through air (short distance ≤ 3 feet) and deposited on host's conjunctiva, nasal mucosa or mouth. But the droplets are not suspended in air [15].

Airborne transmission occurs by airborne droplet nuclei (small particle ≤ 5 μm in size) which are evaporated droplets containing the microorganisms that remain suspended in air for few hours or days. Mycobacterium tuberculosis, Varicella, Rubella, Influenza viruses etc can be transmitted by droplet nuclei [15].

## **2.5. Infecting agents**

**2.1. The high risk areas for HAI**

6 Infection Control

**2.2. Host factors responsible for HAI**

**i.** Repeated hospital admissions

trauma ICUs

**2.3. Source of HAI**

immune system is immature

**vi.** Patients with diabetes, malnutrition

predispose to HAI. The important ones are -

persistent infection.

**2.4. The mode of transmission of HAI may be**

**i.** Overuse or injudicious use of antimicrobials

**iii.** Improper maintenance of operation theatres and ICUs etc

blood or blood products etc) and vector borne (mosquitos, flies, rats etc)

**vii.** Patients with HIV / AIDS etc

Nurseries, Intensive care units (ICUs), Operation theatres (OTs) and Post operative wards, Labour room, Dialysis unit, Organ transplant unit, Oncology wards, Burn units, High

**ii.** Increased number of patients receiving intensive care or long term care facilities

**iv.** Increased survival of low birth weight or premature babies treated in NICUs

**iii.** Extremes of age i.e. in elderly patients the immunity is waning and in newborn the

**v.** Increased incidence of road accidents leading to head injury, spinal cord injury in

HAIs acquired by a patient may be endogenous (autogenous) and exogenous. Endogenous infections are caused by patient's own flora or by carrier state, whereas exogenous infections result from transmission of organisms from various sources via different routes [15]. Exoge‐ nous sources may be other patients with infectious diseases. HCWs carrying MRSA, Multidrug resistant (MDR) Gram negative organisms on hands or dresses, contaminated disinfectant solutions, environmental surfaces especially frequently – touched surfaces e.g. bed rails, furnitures, door latches, toilet seats, telephones etc and even floor, window panes, air condi‐ tioners, renovation work, inefficient sterilization of equipment and devices. Moreover, medications or devices, necessary to cure patient's primary medical condition can also

**ii.** Indwelling medical devices such as urinary catheters, endotracheal tubes, ventilators,

Contact (direct or indirect), droplet, airborne, common vehicle (food, water, medical devices,

artificial heart valves, joint prosthesis etc which break the body's natural barrier to infection, which can also lead to biofilm formation and form a nidus for chronic

Dependency units (HDU) etc are mainly high risk areas for HAI.

The organisms causing HAI are mostly antibiotic resistant, which adds to the increased morbidity and mortality of patients.


Specially Extended spectrum β – lactamase (ESBL producing) or multi / Extreme drug Resistant Gram negative bacteria e.g.


The terms Multidrug resistance and Extreme drug resistance in Gram negative bacteria was introduced by Falagas in 2011 [18]. Multidrug resistance (MDR) is indicated by non-suscept‐ ibility to one or more antibiotics belonging to 3 or more antibiotic classes, whereas Extreme drug resistance (XDR) is indicated by resistance to all available antibiotics.

all types of HAIs occur in HAP [26] and roughly the mortality range from 24 to 76 % in different health care settings [27]. Ventilator associated pneumonia (VAP) is the commonest cause of HAP which occurs after 48 hours of initiating mechanical ventilation [25], [28]. VAP occurs 25% of all ICU infections and caused by multidrug resistantbacteriae.g.Pseudomonasaeruginosa,AcinetobacterbaummaniorCarbepe‐ nemaseproducingEnterobacteriaceae,MRSA,VREetc.Burkholderiasp.andStenotro‐ phomonas maltophila both have a tendancy to colonize respiratory tract rather than to cause invasive disease and are mostly resistant to Carbapenems, because of produc‐ tion of metallobetalactamase(MBL). The high mortality, prolonged ICU stay and

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excessive cost associated with VAP is a real challenge to medical fraternity.

**iii.** Surgical site infections (SSI) – SSIs are the most common nosocomial infection. SSIs are

considered as a performance indicator for quality of health care provided.

**iv.** Catheter Related Blood Stream Infections (CR – BSIs) – These accounts for 50% of all

ICU related bacteremias. CR – BSIs specially central line associated blood stream infections (CLABSIs) in ICU have been reported from USA as 1.8 to 5.2 per 1000 CVC catheter days where as studies from 8 developing countries reported the incidence as 12.5/1000 catheter days [33]. CR – BSIs are actually defined as bacteriaemia or fungiaemia in a patient who has an intravascular devise and a positive result of blood culture from peripheral vein, clinical manifestations and no other apparent source for BSI. The causative agents are Staphylococcus aureus even MRSA, Coagulase negative Staphylococci (CONS), Enterococcus species even VRE, Candida species, Pseudomonas aeruginosa, ESBL and Carbapenemase producing E.coli and Klebsiel‐ la, Burkholderia species etc. Candida species are known to cause CRBSIs in Neonatal ICU (NICU). Traditionally, Amphotericin B and Fluconazole are the only treatment options for invasive fungal disease in the neonate. Though C.albicans is mostly sensitive to Fluconazole, but Fluconazole resistant Candida species and toxicity with

caused by MRSA, VRSA, VISA, VRE, Pseudomonas aeruginosa, Acinetobacter baumani, ESBL and AmpC β – lactamase producing E.coli, Klebsiella, Proteus etc and also by MBL and Klebsiella pneumoniae carbapenemase (KPC) producing Gram negative bacilli. SSIs occur when microorganisms gain access to areas of the body, exposed during surgical procedures and then multiply in the tissues. Mangram et al havedefinedSSIswhichmanifestswithin30daysofa surgicalprocedureorwithinone year if the implant is left in place during the operative procedure and affect either the incision or deep tissue at the site of operation [29]. The intraoperative factors as proper skin preparation, following sterile techniques, traffic in the operating room contrib‐ ute more to SSIs compared to patient related factors e.g. diabetes mellitus, pre exist‐ ing colonization with MRSA etc [30]. SSIs are most commonly reported from surgical ward and CDC in US requires 16 wound and patient characteristics to define SSIs [31]. Though SSIs are preventable, about one fifth (approx. 22%) of all health care associat‐ ed infections are due to SSIs (CDC report). Kirkland et al reported that 60% of pa‐ tientswithSSIsareICUpatients,averagelengthof stayinhospitalis>5daysand5times more likely to be readmitted in hospitals [32]. Hence, rates of SSIs are increasingly

In 2009, Peterson et al used the acronym ESCAPE for MDR organism causing HAI [19].


10-12 % of all HAIs are caused by Enterococci which is the 3rd most common cause of blood stream infection in hospitalized patients. Vancomycin resistant Enterococci (VRE) was first isolated in vitro in 1969 and was described clinically in 1988. The main mechanism is alteration of cell wall precursors. Several resistant genotypes have been detected, of which vanA and vanB are most clinically significant. Vancomycin resistance is transferable to Staphylococcus aureus in vitro. As a life saving measure, treatment option with MDRO is very selective. MRSA strains can be treated by Vancomycin and Linezolid, VRE can be treated by Linezolid; ESBL producers can be treated by β – lactamase inhibitors; both ESBL and AmpC producers can be treated by Carbapenems. But Carbapenem resistant organisms can be treated by Colistin.

Recent studies in India have reported ESBL in 70 – 90% of Enterobacteriaceae, 29% Pseudo‐ monas aeruginosa and 26% of Acinetobacter spp. which is a serious problem [20]. Recently from our hospital prevalence of AmpC β – lactamase and metallobetalactamase (MBL) producing P.aeruginosa strains have been reported as 19.3% in 2009 and 11.4% in 2010 respectively [21], [22].
