The molecular test for pathogenic microorganisms utilizes polymerase chain reaction (PCR) technology to detect and identify bacterial and fungal pathogens with high sensitivity and specificity. This advanced diagnostic method targets microorganisms' genetic material (DNA), allowing for their identification even at very low concentrations. Unlike conventional culture techniques, which can be time-consuming and may fail to detect slow-growing or fastidious organisms, PCR provides rapid and precise results, making it an essential tool in modern microbiology. The test is widely used for diagnosing respiratory, gastrointestinal, bloodstream, urinary tract, and wound infections, aiding in targeted therapy and infection control.
Microorganisms Detected and Clinical Significance
- Staphylococcus aureus* – A significant cause of skin infections, pneumonia, sepsis, and antibiotic-resistant infections.
- Staphylococcus epidermidis* – A commensal skin bacterium that can cause opportunistic infections in immunocompromised patients and those with implanted medical devices.
- Staphylococcus hominis* – A skin-dwelling bacterium that may lead to bloodstream infections in hospitalized patients.
- Staphylococcus haemolyticus* – An emerging multidrug-resistant pathogen associated with catheter-related infections.
- Streptococcus pyogenes/dysgalactiae – Causes pharyngitis, scarlet fever, rheumatic fever, and necrotizing fasciitis.
- Streptococcus pneumoniae – A leading cause of pneumonia, meningitis, otitis media, and sepsis.
- Streptococcus agalactiae (Group B Streptococcus) – A significant cause of neonatal sepsis, pneumonia, and meningitis.
- Streptococcus mitis – A component of oral flora that can cause endocarditis in immunocompromised individuals.
- Streptococcus sanguinis/parasanguinis – Oral streptococci associated with infective endocarditis.
- Streptococcus milleri group (S. constellatus, S. anginosus) – Linked to deep-seated abscesses, including brain and liver infections.
- Streptococcus spp. – Encompasses various species capable of causing systemic and localized infections.
- Enterococcus faecium – A leading cause of hospital-acquired infections, including vancomycin-resistant strains (VRE).
- Enterococcus faecalis – Associated with urinary tract infections, endocarditis, and wound infections.
- Gram-positive cocci (GPCs) – Group – Includes multiple clinically relevant cocci contributing to infections.
- Listeria monocytogenes – A foodborne pathogen causing listeriosis, particularly dangerous for pregnant women and immunocompromised patients.
- Clostridium perfringens – A cause of gas gangrene, food poisoning, and soft tissue infections.
- Escherichia coli – A common cause of urinary tract infections, sepsis, and gastroenteritis.
- Klebsiella pneumoniae – A multidrug-resistant pathogen responsible for pneumonia, bloodstream infections, and UTIs.
- Klebsiella oxytoca – Associated with antibiotic-resistant infections and hemorrhagic colitis.
- Klebsiella spp. (K. pneumoniae, K. oxytoca) – Opportunistic pathogens linked to nosocomial infections.
- Salmonella enterica – A foodborne pathogen causing gastroenteritis, typhoid fever, and systemic infections.
- Enterobacter cloacae – A multidrug-resistant pathogen involved in bloodstream and respiratory infections.
- Enterobacter aerogenes – Common in hospital-acquired infections, particularly in immunosuppressed patients.
- Enterobacter spp. (E. cloacae, E. aerogenes) – Gram-negative bacteria associated with antimicrobial resistance.
- Citrobacter freundii – A cause of urinary tract infections and neonatal meningitis.
- Citrobacter spp. (C. freundii, C. koserii) – Opportunistic bacteria implicated in severe infections in immunocompromised individuals.
- Serratia marcescens/plimutica – A nosocomial pathogen causing urinary tract, wound, and bloodstream infections.
- Proteus vulgaris/penneri – Associated with complicated urinary tract infections and bacteremia.
- Proteus mirabilis – A key pathogen in urinary tract infections and urolithiasis.
- Proteus spp. (P. vulgaris, P. mirabilis, P. penneri) – Gram-negative bacteria known for their role in polymicrobial infections.
- Haemophilus influenzae – A significant cause of respiratory infections, meningitis, and otitis media.
- Haemophilus spp. (H. influenzae, H. parainfluenzae) – Includes respiratory pathogens affecting children and adults.
- Acinetobacter baumannii – A highly resistant pathogen linked to ventilator-associated pneumonia and wound infections.
- Bacteroides fragilis – A significant anaerobic pathogen involved in intra-abdominal and pelvic infections.
- Bacteroides spp. (B. fragilis, B. faecis) – Anaerobic bacteria commonly found in polymicrobial infections.
- Pseudomonas spp. (P. aeruginosa, P. putida, P. stuartii) – Opportunistic pathogens that thrive in hospital environments and cause severe infections.
- Stenotrophomonas maltophilia – A multidrug-resistant pathogen found in respiratory tract infections.
- Candida albicans – The most common fungal pathogen responsible for mucosal and systemic candidiasis.
- Candida glabrata – A yeast species with high resistance to antifungal agents.
- Candida krusei – An inherently fluconazole-resistant fungal pathogen.
- Candida spp. and fungi – Group – Encompasses clinically significant fungi responsible for invasive fungal infections.
*Including Methicillin Resistant strains
Clinical Utility
The molecular PCR test is a crucial tool in infectious disease diagnosis. It offers several advantages over traditional culture-based methods. First, it provides rapid results, often within hours, allowing for timely clinical decision-making. Additionally, PCR is highly sensitive and specific, enabling the detection of low bacterial or fungal loads, even in challenging clinical specimens.
This test is particularly valuable for:
- Early identification of resistant pathogens, facilitating appropriate antimicrobial stewardship.
- Diagnosing polymicrobial infections, where conventional methods may fail to detect all causative agents.
- Guiding targeted antimicrobial therapy reduces the need for empirical broad-spectrum antibiotics and minimizes resistance development.
- Detecting bloodstream infections and sepsis-causing pathogens is critical for managing life-threatening conditions.
- Surveillance of hospital-acquired infections, aiding in infection control measures and outbreak management.
This molecular test enhances the accuracy and speed of pathogen detection by incorporating real-time PCR and multiplex PCR technologies. Its application in respiratory, urinary tract, bloodstream, wound, and gastrointestinal infections makes it an indispensable tool in modern clinical microbiology.
