**Abstract**

*Pseudomonas aeruginosa*, as a gram-negative aerobic rod, is still one of the most resistant agents of nosocomial infections. It is used for the development of respiratory, urinary and wound infections. It causes bacteremia, especially in patients who are hospitalized for anesthesiology and resuscitation department or ICU, who often have respiratory insufficiency and hemodynamic instability and require artificial lung ventilation. Mechanical ventilation itself is a significant risk factor for the development of pseudomonad pneumonia. *Pseudomonas aeruginosa* has enzymes that are encoded on both chromosomes and plasmids, often in combination with other mechanisms of resistance, such as reducing the permeability of the outer or cytoplasmic membrane. Due to carbapenemases, *Pseudomonas aeruginosa* loses sensitivity to carbapenem and becomes resistant to this antibiotic. It also becomes resistant to aminoglycosides, cephalosporins and ureidopenicillins. It is also resistant to Quaternary disinfectants. The reservoir of pseudomonas nosocomial infection is hospital water, taps, shower roses, swimming pools, healing waters and others. The intervention of anti-epidemic measures in the case of infections caused by pseudomonad strains has not yet reached such sophistication as in the case of MRSA for time, personnel and economic reasons. In the absence of an epidemic, intervention in sporadic cases consists of informing nursing staff of the occurrence of a multidrug-resistant agent, including providing all patient demographics and relieving careful adherence to the barrier treatment, cleansing, disinfection and isolation regimen.

**Keywords:** nosocomial infections, respiratory insufficiency, pnemonia, lung ventilation, resistance

## **1. Introduction**

Nosocomial infections (NI) are a global problem in hospital care. This is a significant complication that worsens the prognosis of the underlying disease, increases mortality, prolongs hospitalization, worsens the quality of life of patients and increases the cost of treatment, so NI pays special attention. In the United States, the Center for Disease Control and Prevention (CDC) is the leading authority in this area. CDC procedures and guidelines are the most widely used standard worldwide. In the USA, a nationwide NI surveillance system has been organized since the 1970s. The United Kingdom also has a long tradition in the control of NI, which is organized in the system of laboratory service of the British public health service (Public Health Laboratory Service). The main guarantor, which organizes congresses dedicated to NI, is the Hospital Infection Society (HIS), which publishes a globally

important and recognized journal - the Journal of Hospital Infection [1]. The aim of the journal is to publish high-quality research and information related to the prevention and control of NI [2]. NIs need to be diagnosed and treated in time, but the most important thing is their prevention in various hospital wards, especially in intensive care units. Infections acquired in connection with hospitalization can lead to significant morbidity and mortality, but preventive anti-infective measures can significantly affect these results. Equally important is prevention in hospital staff in order to reduce the risk of infections spreading to other patients and staff. In this way, it is possible to prevent the absence of staff from work, which can have a positive effect on the skills of the staff of the intensive care unit. Nosocomial infections are also associated with financial expenses, which include hospital expenses, reduced productivity of sick staff as well as their income due to absence from work.

*Pseudomonas aeruginosa*, as a gram-negative aerobic rod, is still one of the most resistant agents of nosocomial infections. *P. aeruginosa* causes 10-11% of all NI. This result is due to the resistance of this microorganism to desinfectants and many antimicrobials. It is involved in the development of respiratory, urinary and wound infections. It causes bacteremia, especially in patients who are hospitalized at anesthesiology and resuscitation department or ICU, who often have respiratory insufficiency and hemodynamic instability and require artificial lung ventilation. Mechanical ventilation itself is a significant risk factor for the development of pseudomonad pneumonia. *P. aeruginosa* has enzymes that are encoded on both chromosomes and plasmids, often in combination with other mechanisms of resistance, such as reducing the permeability of the outer or cytoplasmic membrane. Due to carbapenemases, *P. aeruginosa* loses sensitivity to carbapenem and becomes resistant to this antibiotic. It also becomes resistant to aminoglycosides, cephalosporins and ureidopenicillins. It is also resistant to Quaternary desinfectants. The reservoir of pseudomonas nosocomial infection is hospital water, taps, shower roses, swimming pools, healing waters and others. It occurs in sinks, humidifiers, anesthesia machines, inhalers, hand brushes and other places that meet suitable conditions, which means ambient humidity. Pseudomonads contaminate lubricating gels and disinfectants [3].

The intervention of anti-epidemic measures in the case of infections caused by pseudomonad strains has not yet reached such sophistication as in the case of MRSA for time, personnel and economic reasons. In the absence of an epidemic, intervention in sporadic cases consists of informing nursing staff of the occurrence of a multidrug-resistant agent, including providing all patient demographics and relieving careful adherence to the barrier treatment, cleansing, desinfection and isolation regimen [3].

If we add eye, ear, nose, and throat infections to pneumonia, then respiratory tract infections are the most common site of nosocomial infections for almost all age groups in pediatric JIS [4]. Much attention has been paid to ventilator-associated pneumonia (VAP) as the most common and potentially preventable nosocomial infection. Other nosocomial respiratory infections include sinusitis, otitis media and tracheitis. Contamination of the patient's respiratory tract may come from a device with which the patient has been in direct contact, namely an endotracheal tube, nasogastric tube, aspiration catheters, bronchoscopes, but also from a device with which he has not been in direct contact, such as a mechanical ventilator, ventilator hose, nebulizers and devices that supply oxygen. The human vector that most likely transmits infection to a patient is hospital staff. The most common risk factors are poor hand hygiene, insufficient isolation of patients and contaminated objects such as stethoscopes. Family members and other patients may also transmit the infection to patients hospitalized in a pediatric ICU. All of these factors must be considered and controlled to minimize the occurrence of nosocomial respiratory tract infections [2].

**23**

*Pseudomonas aeruginosa* as a Cause of Nosocomial Infections

Nosocomial pneumonia is the second most common nosocomial infection in pediatric ICUs after catheter infections of the bloodstream. Nosocomial infection can occur in any patient, but is most common in infants, young children, and patients over 65 years of age. Patients in pediatric ICUs who are most at risk for pneumonia are patients who have been intubated and mechanically ventilated. The risk increases due to the circumvention and alteration of the host's defenses, as the vocal cords remain open and the risk of aspiration of gastrointestinal contents increases. The risk of nosocomial pneumonia is 6-20 times higher in ventilated patients compared to nonventilated patients. Ventilator-associated pneumonia (VAP) is defined as the development of new pneumonia for at least 48 hours after the start of mechanical ventilation. Independent risk factors for the development of VAP in children are immunodeficiency, immunosuppression and neuromuscular blockade. Other risk factors are genetic syndromes with neuromuscular weakness, burns, steroid administration and total parenteral nutrition [2]. Children have a higher risk of VAP with antibiotics, with a longer stay in the ICU, with catheters in place with a risk of haematogenous spread, treatment with H2-receptor blockers, reintubation and transport outside the ICU during intubation. The presence of a nasogastric tube increases the risk as it provides a direct pathway from the upper gastrointestinal tract to the oropharynx. In-line nebulizers and manipulation of the ventilator circuit can affect the risk of nosocomial pneumonia. VAP in children accounts for 10-26% of nosocomial infections. The incidence of pediatric nosocomial pneumonia within the hospital is highest at the neonatal JIS, followed by the pediatric JIS, and the pediatric ward. Nosocomial pneumonia has the highest mortality of all pediatric nosocomial infections and ranges from 20–70%. Although the duration of endotracheal intubation increases the risk of nosocomial pneumonia, the highest risk is during the first 2 weeks of intubation. Almost all intubated children have a colonized endotracheal tube with nosocomial microorganisms within 5 days [2]. The most frequently identified bacteria in pediatric JIS are gram-negative bacilli, especially *P. aeruginosa*. Mortality is higher with gramnegative microorganisms. *P. aeruginosa* is one of the leading causes of ventilatorassociated pneumonia (VAP) in the US and Europe [5–7]. VAP due to *P. aeruginosa* is increasing in incidence and poses unique challenges for its clinical management.

The diagnosis of VAP in children can be made on a clinical basis without the use of bronchoscopy. A set of clinical diagnostic criteria and alternative criteria that vary with age are given in the table (**Table 1**). The presence of pneumatoceles on chest X-rays in children under 12 months of age meets the radiographic criteria for pneumonia, which are listed in the table. The diagnosis of VAP can be made based on clinical and radiographic criteria. Identification of the causative microorganism is essential for targeted antibiotic therapy. Identification of the microorganism is difficult because endotracheal tube culture is inaccurate due to colonization of the endotracheal tube and upper airways by gram-negative bacilli and staphylococci, which occurs within a few days after intubation. In adult and older children, bronchoalveolar lavage and protected swab specimens have been used successfully. In young children, it is not possible to obtain a protective sample for the size of the required bronchoscope, and the bronchoalveolar lavage performed has a high incidence of contamination. Methods for determining the causative microorganism are positive blood culture that cannot be explained by other sources, positive pleural fluid cultures, and a positive bronchoalveolar lavage sample despite its limitations, >5% of bronchoalveolar lavage cells containing intracellular bacteria and positive

*DOI: http://dx.doi.org/10.5772/intechopen.95908*

**2. Ventilator-associated pneumonia**

**2.1 Symptoms and diagnosis of VAP**
