Infection Management Strategy Based on Prevention and Control of Nosocomial Infections in Intensive Care Units

Infection Management Strategy Based on Prevention and Control of Nosocomial Infections in Intensive Care Units

Sepsis, defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, is a critical condition frequently encountered in intensive care units (ICUs). Without timely and effective treatment, the incidence and mortality of sepsis remain alarmingly high. Given the pivotal role of hospital infection control in managing nosocomial infections in ICUs, this article proposes a comprehensive strategy tailored to the clinical presentation of critically ill patients, the biological characteristics of pathogenic microorganisms, and the unique ICU environment.

The evolution of sepsis definitions, from Systemic Inflammatory Response Syndrome (Sepsis 1.0) to life-threatening organ dysfunction (Sepsis 3.0), has deepened our understanding of severe infections. The Sequential Organ Failure Assessment (SOFA) score, emphasized in Sepsis 3.0, is crucial for evaluating organ damage caused by infection. A SOFA score or its acute change of ≥2 points indicates organ dysfunction or exacerbation, with the severity of infection correlating with the extent of damage. As infection is the primary cause of organ damage in critically ill patients, identifying and treating infectious lesions is paramount. The 2018 Surviving Sepsis Campaign (SSC) guidelines highlight the importance of early detection and control of infectious lesions, recommending the administration of antibiotics within one hour, a significant update from the previous three-hour window. Therefore, clinicians must assess organ function in sepsis or septic shock patients, strive to identify, control, and remove infectious lesions, and initiate early empirical use of targeted antibiotics alongside tissue perfusion-targeted hemodynamic therapy.

Advancements in diagnostic techniques have demonstrated that ultrasound is superior to bedside X-rays for diagnosing pulmonary infections. Critical ultrasound can replace or support X-ray and CT images in screening or excluding infectious lesions. For instance, ultrasound can quickly identify infections in the chest (pulmonary infection, infective endocarditis, and pleural effusion), abdominal and pelvic cavity (biliary tract infection, gastrointestinal effusion, abdominal effusion, parenchymal organ liquid lesions), and central nervous system (intracranial hypertension). Different characteristics of lung infections on CT can also be visualized through ultrasound. For example, consolidation and focal exudate, typical of lobar pneumonia and bronchopneumonia, appear as debris signs and air bronchograms on ultrasound. Interstitial pneumonia, characterized by diffuse exudative lesions in bilateral lungs, shows B-line signs in ultrasonograms. Pneumonia caused by different pathogens exhibits various imaging characteristics, aiding in pathogen identification. For instance, Pneumococcus, Staphylococcus aureus, Klebsiella pneumoniae, and Legionella cause consolidation changes, while mycoplasma, chlamydia, Pneumocystis Carinii, and Cytomegalovirus cause diffuse interstitial changes. However, hematogenous infections and urinary tract infections lack definitive ultrasound manifestations, necessitating consideration after excluding parenchyma or cavity infection. Additionally, retroperitoneal and sinus infections may be more cryptic and challenging to diagnose.

The essence of nosocomial infections lies in the opening of pathways and the destruction of barriers. Critically ill patients often require the insertion of large catheters (e.g., endotracheal intubation, central venous catheters, urinary catheters, gastric tubes, and various drainage tubes) due to the severity of their illness and complex treatment regimens. These catheters create new pathways for bacterial invasion, disrupting the body’s original mucosal and vascular barriers, thereby increasing the risk of nosocomial infections. Patient trauma, deterioration of self-defense mechanisms (e.g., weakened coughing ability and catheter placement), and barrier function impairment from treatments (e.g., surgery and trauma) further elevate infection risk. Once bacteria invade the body through any route, blood flow can facilitate the spread of infection to multiple body parts, leading to increased infection severity or delayed healing. Therefore, preventing and controlling nosocomial infections are critical to managing infections in critically ill patients.

Differentiating between colonization and infection can reduce antibiotic use and drug resistance. Colonization, a precursor to infection, does not require antibiotic intervention, making it essential for clinicians to distinguish between the two. ICUs are complex environments harboring various pathogens, and detecting pathogens in critically ill patients does not necessarily indicate infection. Misinterpreting colonization as infection can lead to antibiotic abuse and resistance. Factors to consider in distinguishing colonization from infection include qualified smears and culture results, clinical signs and symptoms (e.g., fever, rapid heart rate, rapid breathing rate, low blood pressure, and high white blood cell count), and host factors (e.g., underlying diseases, immune status, prior antibiotic treatment, and risk factors such as mechanical ventilation and duration). Preventive antibiotic use among ICU patients should be avoided, and reducing antibiotics for colonizing bacteria can decrease bacterial drug resistance. Additionally, attention to the cleanliness and care of drainage of infected lesions, as well as the skin, oral cavity, and perineum, is crucial.

Understanding the pathogenic characteristics of different pathogens is essential. Gram-negative bacteria are widespread in ICUs and are classified as fermenting or non-fermenting based on their ability to use glucose. For light-to-moderate fermentation (non-ESBL Enterobacteriaceae) infections (e.g., urinary tract infections, liver abscesses, biliary tract infections, peritonitis, and nosocomial infections), a β-lactamase inhibitor may be selected based on drug sensitivity results. Intractable ICU fermenters primarily include ESBL- and AmpC-producing Enterobacteriaceae, such as Escherichia coli, Klebsiella, Proteus mirabilis, and Enterobacter cloacae. Carbapenem antibiotics are the first choice for severe infections with ESBL-producing Enterobacteriaceae. Carbapenem-resistant Enterobacteriaceae (CRE) are a leading cause of high mortality in severe ICU infections. As fermenting bacteria are primarily derived from the human body, drainage and isolation are crucial for controlling CRE progression and spread. Tigecycline or polymyxin-based combinations with carbapenem may be suitable for such patients, but emphasis should be placed on preventing and controlling nosocomial infections. Non-fermentative bacteria, including Pseudomonas aeruginosa, Acinetobacter, Alcaligenes, Burkholderia, Flavobacterium, and Stenotrophomonas Maltophilia, are primarily conditional pathogens. The proportion of non-fermenting bacteria in gram-negative bacilli infections has increased significantly, likely due to iatrogenic factors. Improving awareness of nosocomial infection prevention and control is key to addressing this issue.

Gram-positive bacteria primarily consist of Staphylococcus aureus and enterococci. Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are the main pathogens for intractable ICU infections with poor prognoses. Risk factors for MRSA infection include advanced age, ICU admission, mechanical ventilation, catheter placement, parenteral nutrition, renal replacement therapy, surgery, broad-spectrum antibiotics, hormonal applications, and drug injections. Controlling nosocomial infection is essential for managing MRSA, with vancomycin being the first-line treatment. Enterococcus, a normal flora of humans, has become multidrug-resistant due to antibiotic abuse. Risk factors for VRE infection include severe illness, prolonged ICU stays, severe immunosuppression, major surgical procedures, invasive procedures, VRE colonization, broad-spectrum antimicrobial therapy, and vancomycin treatment. VRE can be transmitted between patients and through contaminated environments and medical devices. Strict compliance with nosocomial infection control strategies, such as drainage, isolation, and aseptic procedures, is crucial for managing VRE.

Fungal infections in ICUs primarily involve yeasts and molds, with Candida being the most significant yeast. Candida albicans is the most common pathogen, but non-albicans Candida species, such as Candida glabrata, Candida tropicalis, Candida parapsilosis, and Candida krusei, are increasingly prevalent. Candida infections can arise from endogenous factors (gastrointestinal and mucous membrane colonization) and exogenous factors (contact transmission and infusion contamination). Candida’s ability to colonize multiple body sites poses a risk for candidemia. Abdominal surgery is another risk factor for candidemia, and clinicians should consider Candida infection if patients deteriorate despite antibiotic treatment. Triazoles are the first-line treatment for Candida, with echinocandins preferred for patients with renal insufficiency. Mold infections, particularly Aspergillus, are also common in ICUs. Aspergillus is spread through the air and primarily affects immunocompromised patients. Voriconazole is the first-line treatment for Aspergillus infections, and maintaining air cleanliness and proper environmental humidity is crucial for maximizing treatment efficacy.

Immunocompromised patients, including those with hematological or immune diseases, are susceptible to infections with Pneumocystis Carinii and cytomegalovirus (CMV). Pneumocystis Carinii pneumonia (PCP) is an interstitial plasma cell pneumonia caused by Pneumocystis, with increased incidence due to immunosuppressive agents and cancer chemotherapy. Clinical manifestations include dry cough, shortness of breath, difficulty breathing, high fever, and cyanosis. CT imaging shows glassiness and patchy, nodular, and reticulate appearances. Hexamin staining and PCP-DNA detection are diagnostic tools, with sulfonamides being the first-line treatment, possibly combined with caspofungin. CMV infection presents with fever, cough, muscle aches, chest pain, neutropenia, and lymphopenia, with bilateral pulmonary infections showing patchy or frosted glass and solid changes on imaging. Ganciclovir is effective for CMV infections, and the necessity of hormonal and immunoglobulin treatments requires further clinical evidence.

Atypical pathogen infections, including mycoplasma, chlamydia, and Legionella, are conditional pathogens. Mycoplasma and chlamydial infections often affect younger patients with minimal underlying disease, presenting with persistent cough, no sputum, and peripheral blood leukocytes <10×10^9/L. Imaging shows central nodules of lobules, tree-bud signs, ground-glass opacities, and bronchial wall thickening. Legionnaires' disease, more common in the elderly, presents with extra-pulmonary symptoms and glassy imaging with solid consolidation. Mycoplasma pneumoniae has high resistance to macrolides in China but remains sensitive to doxycycline, minocycline, or quinolones. Quinolones and macrolides are the first-line treatments for chlamydia and Legionella. Prevention, particularly awareness of nosocomial infections, is crucial for managing atypical pathogens.

In summary, this article proposes an ICU infection management strategy centered on the prevention and control of nosocomial infections. Based on the ICU environment, pathogenic bacteria characteristics, and the doctor-patient relationship, we map the distribution pattern of common ICU bacteria and propose hospital management strategies. These strategies include closing pathways to reduce bacterial load, enhancing drainage to improve infection focus removal, isolating and cleaning the environment to avoid cross-dissemination, and distinguishing infection from colonization to reduce unnecessary antibiotic use and drug resistance. The BEAT-Hands protocol emphasizes identifying infections and colonization of common pathogens in the body, environment, air, and oropharynx, and clarifying changes in the patient’s infection profile during medical procedures. Focusing on nosocomial infection prevention and control is essential for reducing ICU infection incidence.

In conclusion, ICU infections differ from traditional infections due to the infected population, ICU environment, and microbial characteristics. Effective ICU infection management relies on a series of measures centered on nosocomial infection prevention and control, rather than excessive antibiotic use. Emphasizing environmental and air cleanliness, preventing colonization from turning into pathogenesis, and reducing pathogenic pathways to enhance pathogen clearance are crucial. Protecting critically ill patients from new pathogens or exacerbating existing infections is the essence of ICU infection therapy and the key to addressing future serious infections and drug resistance.

doi.org/10.1097/CM9.0000000000000029

Was this helpful?

YesNo

0 / 0