**2. Types of microbial and parasitic infections**

In tertiary care, the variety of disease-causing bacteria and parasites is considerable. The previously described microorganisms, including bacteria, viruses, fungi, and parasites, provide unique identification, management, and prevention challenges. Bacterial infections are a significant source of worry since they may range from minor diseases to severe and possibly deadly illnesses [1]. Viral infections, such as those caused by influenza, RSV, and SARS-CoV-2, may manifest in acute, chronic, or latent forms, offering treatment issues [2]. *Candida* and *Aspergillus* are typical fungal infections, usually opportunistic and typically seen in people with impaired immune systems [3]. Despite being uncommon in developed nations, parasitic diseases remain a cause of concern for those who have gone to or are now living in locations where such illnesses are common. The causal agents of such illnesses are often

identified as Cryptosporidium, Giardia, and certain helminths [4]. Understanding the many types of infections is the foundation for effective infection detection, treatment, and prevention in tertiary care.

#### **2.1 Bacterial infections**

The potential severity and breadth of clinical problems induced by bacterial infections remain significant concerns in tertiary care settings. Bacteria are responsible for various clinical symptoms, including but not limited to pneumonia, sepsis, skin, surgical wounds, and urinary tract infections [5]. Pneumonia, which is usually caused by bacterial agents such as *Streptococcus pneumoniae*, *Klebsiella pneumoniae*, and *Pseudomonas aeruginosa*, is a common disease among hospitalised patients, especially those on mechanical ventilation [6]. Bacterial pneumonia may cause severe morbidity and death, especially in those with impaired immune systems or pre-existing lung diseases. As a result, prompt detection and management are critical in improving patients' prognoses.

Bacteremia and sepsis are frequent bacterial diseases seen in tertiary care settings, generally due to the spread of a localised infection. According to Seymour et al. [7], the aetiology of these disorders is commonly related to pathogens such as *Staphylococcus aureus*, which includes methicillin-resistant *S. aureus* (MRSA) and different Enterobacteriaceae species. Infections' rapid development and high death rates demand prompt diagnosis and urgent treatment.

Bacterial infections, such as surgical site infections and skin and soft tissue infections, are common in tertiary care settings. Such infections, such as surgical lacerations or injuries, are frequently associated with integumentary system violations. They can be caused by various bacteria, including *S. aureus*, Streptococcus pyogenes, and several gram-negative bacteria [8]. The infections indicated above have the potential to cause significant consequences such as poor wound healing, abscess development, and, in severe cases, necrotizing fasciitis.

Urinary tract infections (UTIs) are a typical kind of bacterial infection in tertiary care, with *Escherichia coli*, *K. pneumoniae*, and *Proteus mirabilis* being the most common pathogens [9]. Although urinary tract infections (UTIs) are often considered minor, they may cause significant consequences in hospitalised patients, such as pyelonephritis and sepsis.

Healthcare-associated infections (HAIs), also known as nosocomial infections, are bacterial infections often observed in tertiary care settings. Nosocomial infections occur inside a healthcare institution and are caused by various bacterial pathogens. According to Weiner-Lastinger et al. [10], the presence of infections such as ventilator-associated pneumonia (VAP), catheter-associated urinary tract infections (CAUTIs), and central line-associated bloodstream infections (CLABSIs) presents significant challenges due to their potential severity and increased susceptibility to antimicrobial resistance.

Identification of bacterial infections needs a thorough examination of clinical symptoms and diagnostic methods performed in a laboratory environment. Microbiological cultures of various physiological fluids, such as blood, sputum, urine, and wound swabs, may be used in diagnostic investigations. Furthermore, molecular diagnostic methods like polymerase chain reaction (PCR) testing may be used. The rapid and exact identification of the etiological agent is critical in guiding antibiotic treatment.

Bacterial infections are frequently treated in tertiary care settings by administering systemic antibiotics. The proper antibiotic is chosen based on the discovered or

suspected etiological agent's susceptibility to antibiotics, the patient's overall health, and the probability of medication interactions. In severe infections, beginning empirical broad-spectrum antibiotic treatment is routine before microbiological data are available. Following identifying the causal bacterium and its antibiotic susceptibilities, the treatment may be de-escalated, according to Barlam et al. [11].

Antimicrobial resistance is becoming more concerning, particularly in tertiary care settings where potent and broad-spectrum medicines are often used. Antibiotic abuse and usage have been linked to the rise of multidrug-resistant organisms (MDROs) such as MRSA, vancomycin-resistant enterococci (VRE), and carbapenemresistant Enterobacteriaceae (CRE) [12]. Infections generated by Multidrug-Resistant Organisms (MDROs) may provide considerable treatment hurdles, possibly leading to poor patient outcomes.

#### **2.2 Viral infections**

The fast spread of viral infections, as well as the associated morbidity and death, are significant concerns in tertiary care settings. In these circumstances, the range of viral infections reported includes respiratory viruses such as influenza and respiratory syncytial virus (RSV), gastroenteric viruses such as Norovirus, and bloodborne viruses such as hepatitis B and C, as well as HIV [13].

In tertiary care settings, the transmission of respiratory viral infections is a substantial concern, especially in highly crowded hospital wards or during times of seasonal frequency. On a worldwide scale, influenza is a significant contributor to severe respiratory disease, with the potential to cause serious consequences such as respiratory failure, pneumonia, and death. According to Iuliano et al. [14], this is especially true for high-risk groups such as the elderly, immunocompromised persons, and those with chronic medical issues. Although RSV is usually associated with moderate sickness in children, it may cause severe disease in immunocompromised adults or have pre-existing lung disorders [15].

The advent of novel coronavirus strains, such as SARS-CoV-2, which caused the COVID-19 pandemic, has drawn attention to the potential dangers of viral infections in hospital settings in recent years. According to Huang et al. [16], the COVID-19 pandemic has had a significant impact on the tertiary healthcare sector owing to its rapid transmission, the range of illness severity ranging from mild symptoms to severe pneumonia and multi-organ failure, and the strain it has placed on healthcare resources.

Gastroenteric viruses, such as Norovirus, significantly cause morbidity in tertiary care settings. According to Lopman et al. [17], Norovirus is a leading cause of acute gastroenteritis and has been related to outbreaks in healthcare institutions due to its high infectivity and environmental durability.

Bloodborne viruses such as hepatitis B and C, as well as HIV, are also common in tertiary care settings. These diseases may be transmitted by contact with contaminated body fluids, typically due to unsafe injection practices or other breaches in infection control methods. According to Stanaway et al. [18], the presence of these viruses in the body might lead to serious health consequences such as liver disease and AIDS.

Identifying viral infections in tertiary care settings is often accomplished via molecular diagnostic methods such as polymerase chain reaction (PCR). This approach allows for the rapid and accurate identification of viral nucleic acids in patient specimens. According to Schuller et al. [19], serological testing for specific *Microbial and Parasitic Infections in Tertiary Care: Diagnosis, Treatment, and Prevention… DOI: http://dx.doi.org/10.5772/intechopen.112171*

viruses may be used, in which antibodies against the virus are detected in the patient's blood.

Given the lack of specific antiviral medicines for all viral strains, managing viral infections in tertiary healthcare settings may be challenging. When antiviral therapy is available, it has the potential to significantly reduce both the frequency of illness and the number of fatalities caused by it. Antiviral medication has been shown to reduce the intensity and duration of influenza infection, especially when taken early [20]. Supportive care, such as oxygen therapy or mechanical ventilation in situations of severe respiratory viruses, is seen as a critical component of treatment.

Antiviral drugs have been more widely available in recent years, covering a more extensive range of viral illnesses. For example, the administration of direct-acting antivirals has been found to achieve cure rates surpassing 90% for hepatitis C, therefore revolutionising the treatment of this hitherto difficult-to-manage illness. The use of antiretroviral medication in the treatment of HIV has dramatically changed the care of people infected with this virus, transforming a once fatal sickness into a manageable, chronic condition [21].

Avoiding viral infections in tertiary care cannot be emphasised, especially given the limited treatment options for many viral disorders. These precautions include general infection prevention tactics, such as vaccination and hand cleanliness, and specific precautions for specific viruses. For respiratory viruses, respiratory and contact precautions are required, while standard measures are advocated for bloodborne viruses [22].

#### **2.3 Fungal infections**

Fungal infections are becoming more common in tertiary care settings, particularly among patients with impaired immune systems and those who use invasive medical equipment. Fungal pathogens, such as *Candida*, *Aspergillus*, and *Cryptococcus*, are responsible for severe infections that cause significant morbidity and death [23].

Candida species are the most common cause of fungal infections in hospitals. Candida species may cause various illnesses, from superficial mucocutaneous infections to more invasive severe disorders, including candidemia and disseminated candidiasis. Candida is a primary etiological agent of bloodstream infections connected with healthcare institutions [24], and it can potentially cause sepsis and multi-organ failure. According to Forsberg et al. [25], the introduction of Candida auris is a reason for worry because of its antibiotic resistance, ability to cause severe disease, and high fatality rates.

*Aspergillus* is a notable fungal infection often found in tertiary care settings. *Aspergillus* typically causes pulmonary infections, which may range from the creation of an aspergilloma, a fungal aggregation in the lungs, to the development of invasive pulmonary aspergillosis. This severe condition can spread to other internal organs. According to Patterson et al. [26], the frequency of *Aspergillus* infections is exceptionally high in people with impaired immune systems, such as those with leukaemia or who have had stem cell or organ transplantation.

*Cryptococcus* is a well-known fungal infection that may cause meningitis. This yeast is persistent in people living with HIV/AIDS. Despite substantial advances in antiretroviral treatment, cryptococcal meningitis remains a leading cause of death among these people [27].

The identification of fungal infections in tertiary care settings might need to be revised. Traditional approaches, like culture and microscopy, may need to be faster and more sensitive. Recent advances in diagnostic procedures, such as antigen and molecular assays, have increased efficiency and accuracy in identifying fungal infections [28].

Antifungal drugs such as azoles, echinocandins, and polyenes are extensively used to treat fungal infections. The increasing prevalence of drug-resistant fungus, such as Candida auris, provides significant challenges for medical management [29]. Furthermore, as observed by Ashbee et al. [30], administering antifungal medication may provide issues owing to possible drug-drug interactions and adverse responses, particularly in persons with numerous comorbidities or undertaking other complex regimens.

In tertiary care, fungal infections are prevented through a mix of standard infection control measures, including hand hygiene and environmental cleaning, as well as particular interventions for high-risk patients. According to Tortorano et al. [31], these approaches may include preventive antifungal medication for select immunocompromised individuals.

#### **2.4 Parasitic infections**

The incidence of parasite diseases is a significant concern in tertiary care hospitals, particularly among patients with impaired immune systems or who have visited or relocated from locations where such illnesses are common. According to Torgerson et al. [32], parasites such as Plasmodium (the agent responsible for malaria), Toxoplasma, and several forms of helminths (worms) may cause severe sickness in individuals.

Malaria caused by Plasmodium species remains a major global health issue, with an annual report of hundreds of millions of cases and hundreds of thousands of deaths, mainly in Sub-Saharan Africa [33]. Malaria is common in people who have travelled from endemic areas to tertiary care settings. According to White et al. [34], the sickness may cause symptoms ranging from mild influenza-like symptoms to serious consequences such as cerebral malaria, severe anaemia, and multi-organ failure.

The parasite Toxoplasma gondii is responsible for Toxoplasmosis, a severe illness. Although most infections cause no or relatively moderate symptoms, those with impaired immune systems, such as those with HIV/AIDS or on immunosuppressive medication, are more likely to develop serious diseases. Toxoplasmosis may cause encephalitis, a severe brain infection, and damage to other organs in patients [35].

Helminthic infections caused by several worm species may be a significant issue in tertiary care settings. The parasitic organisms described above include soil-transmitted helminths such as hookworms, roundworms, and whipworms, as well as other helminths such as schistosomes and filarial worms. Although many helminth infections cause subtle symptoms, they can potentially cause catastrophic illnesses such as malnutrition, organ dysfunction, and severe systemic disease [36].

Identifying parasite infections may be difficult, needing specific laboratory methods such as microscopy, antigen testing, or molecular studies. Suboptimal patient outcomes may occur from diagnostic delays or mistakes [37]. Antiparasitic medicines are routinely used as part of the ordinary course of therapy for parasitic illnesses. However, the particular treatment plan may vary significantly based on several circumstances, including the kind of parasite implicated and the individual patient's features. In certain circumstances, such as helminthic infections, surgical intervention may be required [38].

*Microbial and Parasitic Infections in Tertiary Care: Diagnosis, Treatment, and Prevention… DOI: http://dx.doi.org/10.5772/intechopen.112171*

Preventing parasitic infections in tertiary care settings necessitates a multifaceted approach that includes universal infection control measures, such as meticulous hand hygiene and tailored interventions based on the specific parasite in question. According to Leder et al. [39], malaria prevention in travellers includes antimalarial treatment and mosquito-bite avoidance techniques.

### **3. Diagnosis and treatment of infections**

The diagnostic and treatment procedures are critical in managing microbial and parasite illnesses in a tertiary care context. This part delves into the nuances of identifying these illnesses, the problems experienced throughout the process, the need for a timely and correct diagnosis, and the many therapy options for different infections. Furthermore, it emphasises the critical need for antibiotic stewardship, focusing on their role in a treatment strategy. To properly navigate this complex terrain, each component must be deconstructed, providing a complete understanding of the purpose and value of diagnosis and therapy in the battle against microbial and parasitic illnesses.

#### **3.1 Challenges associated with diagnosis**

Identifying and classifying microbial and parasite diseases in tertiary care settings presents several challenges. A significant worry is the wide variety of possible infections and the wide range of symptoms they might cause, which often resemble other illnesses. This characteristic may make it difficult to differentiate between infections and non-infectious diseases.

Several standard diagnostic tests, including culture and microscopy, need to be improved in terms of sensitivity, specificity, and time-consuming. The existence of these limits may result in a delay in the detection and care of medical issues, which may have negative repercussions for the patient.

According to Opota et al. [40], identifying some infections, notably certain bacteria and fungi, may be challenging owing to their complex cultivating procedure. For example, some fastidious bacteria need exact environmental parameters for multiplication, and certain varieties of fungus may take a long period to mature.

Infectious illnesses, both developing and re-emerging, are a significant source of worry. Emerging viruses, such as the SARS-CoV-2 virus that causes COVID-19, may provide problems to present diagnostic procedures, necessitating the development of innovative diagnostic tools [41].

#### **3.2 Importance of timely and accurate diagnosis**

For various reasons, accurate and timely detection of microbial and parasite diseases is critical. The timely beginning of proper therapy can reduce the severity of the disease, reduce the risk of complications, and improve patient outcomes.

A correct diagnosis helps prevent unnecessary or inappropriate treatment, such as using antibiotics for viral infections, which can contribute to antibiotic resistance [42]. Furthermore, it can potentially reduce the unnecessary use of healthcare resources.

Making an accurate diagnosis is critical in infection management and prevention. According to Siegel et al. [22], appropriate isolation and disinfection methods are critical to reducing infection inside healthcare institutions.

#### **3.3 Treatment options for different types of infections**

The treatment of microbial and parasitic diseases in tertiary care settings depends on the type of illness and the patient's unique clinical presentation. Antibiotics are the mainstay of treatment for bacterial illnesses. The type of bacterium, the location of the infection, the patient's medical history, allergies and other conditions, and the prevailing antibiotic resistance patterns in the region all influence antibiotic selection.

Antiviral medications are routinely used to treat viral infections, albeit the specific drug used depends on the kind of virus involved. Antiretroviral medication is typically used to treat HIV, but direct-acting antivirals are commonly used to treat hepatitis C.

Antifungal medications such as azoles, echinocandins, and polyenes are often used to treat fungal infections, with the exact drug chosen depending on the kind of fungus and the severity of the illness [26].

Antiparasitic medications are used to treat parasitic infections, with the kind of parasite used to choose which drug to use. According to Keiser and Utzinger [38], antimalarial medications are used to treat malaria, while antihelminthic treatments are used to treat helminth infections.

#### **3.4 Importance of appropriate use of antibiotics**

The correct use of antibiotics for bacterial infections is critical in preventing antibiotic resistance formation and spread, a significant global public health concern. According to Dellit et al. [43], practical antibiotic usage comprises only using them when essential, choosing the most appropriate antibiotic, and providing it at the proper dose and time.

Antibiotic overuse may result in the establishment of resistant bacterial strains, making future infections more difficult to treat and increasing the chance of complications and fatality [44]. Furthermore, it could encourage the spread of antibioticresistant germs inside healthcare institutions, exacerbating the problem.

Aside from choosing the appropriate antibiotic, it is critical to reassess the need for antibiotics in light of new evidence, such as culture results. According to Dellit et al. [43], using a de-escalation strategy is a realistic way to reduce antibiotic misuse and the chance of resistance.

Antibiotic stewardship plans have grown increasingly common in tertiary care settings in recent years to improve the effectiveness of antibiotic use. This is being done to address the previously identified problem. The courses in question use a multidisciplinary approach that draws on the experience of various healthcare experts, including infectious disease specialists, pharmacists, and microbiologists. According to Baur et al. [45], there is evidence that they may improve patient outcomes, reduce antibiotic resistance, and reduce healthcare costs.

### **4. Antimicrobial stewardship in tertiary care**

Given the rising frequency of antimicrobial resistance and the slow progress in the discovery of new medications, it is clear that our current arsenal of antimicrobial agents requires careful management. Recognising this reality has led to the developing and implementing antimicrobial stewardship programmes, particularly at tertiary healthcare facilities that regularly meet complex and life-threatening illnesses. This

*Microbial and Parasitic Infections in Tertiary Care: Diagnosis, Treatment, and Prevention… DOI: http://dx.doi.org/10.5772/intechopen.112171*

section aims to offer a clear description of antimicrobial stewardship, underline the need to use antibiotics responsibly, and explain the many techniques used in tertiary care settings to improve the success of these programmes.

#### **4.1 Definition of antimicrobial stewardship**

Antimicrobial stewardship refers to structured efforts to improve and assess the prudent use of antimicrobial medicines by advocating for the most appropriate antimicrobial medication regimen, dose, treatment duration, and administration method [43]. The goal is to achieve the best clinical outcomes for antimicrobial use, reduce toxicity and other adverse outcomes, reduce healthcare costs for infections, and limit the evolution of antibiotic-resistant strains [11].

#### **4.2 Importance of appropriate use of antibiotics**

The careful use of antibiotics is a critical component of antimicrobial stewardship. Given its prominence as a significant global health concern, preventing antibiotic resistance formation and spread is critical. According to Ventola [44], the overuse and misuse of antibiotics may lead to the growth of resistant bacteria, which can complicate the treatment of future infections and increase the chance of bad outcomes and death.

According to Hicks et al. [42], improper antibiotic use may result in avoidable unpleasant responses, superimposed infections, and significantly increased medical costs. As a result, ensuring prudent antibiotic use entails more than merely avoiding resistance. It is a comprehensive strategy aimed at improving patient safety and quality of treatment.

#### **4.3 Strategies for antimicrobial stewardship in tertiary care**

Antibiotic stewardship implementation in tertiary care settings is usually marked by various measures to improve antibiotic usage efficacy. According to Baur et al. [45], the treatments above include prospective measures such as audit and feedback, formulary limitation and pre-authorisation, education, recommendations and therapeutic pathways, and antimicrobial cycling.

Prospective audit and feedback comprise a thorough examination of the acceptability of antimicrobial medication after its beginning, followed by constructive comments to the physician. Prescribers must obtain authorisation before prescribing specified antimicrobial medicines due to the introduction of formulary limitations and pre-authorisation procedures.

The primary goal of education is to improve prescribers' awareness of antimicrobials and the development of resistance. Meanwhile, guidelines and therapeutic pathways provide scientifically backed recommendations for treating specific illnesses.

Antimicrobial cycling is the systematic rotation of certain antibiotic classes to minimise the selection pressure that leads to the development of resistance. Tactics are chosen based on various factors, including the incidence of resistance, accessible assets, and organisational standards.

Furthermore, using computer-based tools for prescription and decision support may help healthcare practitioners choose appropriate antimicrobial therapies while considering the patient's clinical state and regional resistance trends [46].

*Quick diagnostic assays* are a promising method that may speed pathogen identification and antibiotic susceptibility profiling. This, in turn, may allow for the rapid beginning of tailored therapy while reducing the need for broad-spectrum antimicrobials, hence improving treatment efficacy.

To achieve desired results, the strategies above must be integrated into a comprehensive antimicrobial stewardship programme supported by hospital leadership, involving all healthcare professionals involved in antimicrobial use and consistently monitoring and providing feedback on antimicrobial use and resistance to prescribers [11].
