Laboratory Diagnosis of Klebsiella PDF

Laboratory Diagnosis of Klebsiella Klebsiella is a genus of Gram-negative bacteria that can cause various infections in humans. Accurate diagnosis is crucial for effective treatment. Introduction to Klebsiella Gram-Negative Bacilli Facultative Anaerobes Klebsiella are Gram-negative...

Laboratory Diagnosis of Klebsiella Klebsiella is a genus of Gram-negative bacteria that can cause various infections in humans. Accurate diagnosis is crucial for effective treatment. Introduction to Klebsiella Gram-Negative Bacilli Facultative Anaerobes Klebsiella are Gram-negative bacteria, meaning they stain pink Klebsiella can survive with or under a microscope, with a without oxygen, making them characteristic capsule surrounding adaptable to different them. environments. Ubiquitous in Nature Opportunistic Pathogens These bacteria are commonly found in the environment, Klebsiella typically become including soil, water, and the pathogenic when the host's gastrointestinal tracts of humans immune system is compromised or and animals. weakened. Epidemiology and Clinical Significance Klebsiella is a prevalent bacterium found in various environments, including soil, water, and human intestines. It can cause a wide range of infections, especially in individuals with weakened immune systems. Klebsiella is a significant cause of healthcare-associated infections, particularly pneumonia, urinary tract infections, and wound infections. It is also responsible for community-acquired infections, primarily in individuals with underlying health conditions. 10% 20% 50% Hospital Infections Pneumonia Drug Resistance Klebsiella contributes to approximately 10% Klebsiella pneumonia is a common cause of Klebsiella strains have developed resistance of hospital-acquired infections. pneumonia, especially in patients with to multiple antibiotics, making treatment weakened immune systems. challenging. Klebsiella Taxonomy and Identification Genus Klebsiella Species Identification Klebsiella belongs to the family Enterobacteriaceae, a Identification of Klebsiella species relies on a diverse group of Gram-negative bacteria. These combination of phenotypic and genotypic methods. bacteria are commonly found in the environment, Traditional methods include culture characteristics, particularly in soil, water, and the gastrointestinal biochemical tests, and antimicrobial susceptibility tracts of humans and animals. testing. Molecular techniques, such as polymerase The genus Klebsiella includes several species, with chain reaction (PCR) and DNA sequencing, are Klebsiella pneumoniae being the most clinically increasingly used for accurate identification and strain significant. typing. Specimen Collection and Transport Specimen Selection Appropriate specimens are crucial for accurate diagnosis. Common specimens include respiratory secretions, blood, urine, and cerebrospinal fluid. Collection Procedures Sterile collection techniques are essential to minimize contamination and ensure accurate results. Transport Media Specimens should be transported in appropriate media to preserve viability and prevent overgrowth of contaminants. Transport Time Rapid transport is essential to ensure the integrity of specimens and minimize the risk of bacterial overgrowth. Labeling and Documentation Accurate labeling and proper documentation of specimen collection details are vital for laboratory processing and results interpretation. Gram Staining and Microscopic Examination Gram staining is a crucial initial step in the laboratory diagnosis of Klebsiella. This differential staining technique differentiates bacteria based on their cell wall composition, highlighting Klebsiella's characteristic gram-negative morphology. Microscopic examination of gram-stained smears reveals Klebsiella as short, plump, encapsulated, and often arranged in pairs or short chains. This visual identification provides a presumptive diagnosis, prompting further investigations. Culture Characteristics on Selective Media Selective Media Colony Morphology Isolation and Identification Klebsiella species are Klebsiella colonies are typically commonly isolated on selective large, mucoid, and exhibit a Isolation of pure cultures from media like MacConkey agar, distinctive pink-red color on clinical specimens is crucial for which inhibits the growth of MacConkey agar due to lactose accurate identification and most gram-positive bacteria. fermentation. antimicrobial susceptibility testing. Biochemical Identification Tests 1 1. Carbohydrate 2 2. Indole Fermentation Production Tests Klebsiella typically does Klebsiella species exhibit not produce indole, while specific patterns of some related species do. fermentation reactions. 3 3. Citrate 4 4. Urease Test Utilization Test Klebsiella species Klebsiella species utilize produce urease, an citrate as a carbon enzyme that hydrolyzes source. urea. Biochemical reaction Laboratory diagnosis 1. Sugar fermentation Specimen : urine, pus, CSF, blood, with production of acid sputum 1. Direct smear stained and gas with Gram stain 2. Indole negative 2. Culture on MacConkey’s 3. Methyl red negative 4. TSI; A/A medium 5. H2S –ve 3. On blood agar: string test 7. Citrate positive 4. The colonies are identified by 8. Urease positive morphology and biochemical reactions Antimicrobial Susceptibility Testing Antibiotic Susceptibility Testing Minimum Inhibitory Concentration (MIC) This determines the effectiveness of antibiotics The MIC is the lowest concentration of an against isolated Klebsiella strains. The Kirby- antibiotic that inhibits visible bacterial growth. It Bauer disk diffusion method or broth provides a quantitative measure of antibiotic microdilution methods are used to assess sensitivity. antibiotic sensitivity. Antibiotic Resistance Mechanisms Klebsiella can exhibit various resistance mechanisms like beta-lactamases, aminoglycoside modifying enzymes, and efflux pumps. Molecular Techniques for Identification 1 1. Polymerase Chain 2 2. Real-Time PCR Reaction (PCR) Quantitative real-time PCR provides rapid identification PCR amplifies specific DNA and quantification of target sequences for detection and genes. characterization of Klebsiella species. 3 3. Sequencing 4 4. Multiplex PCR DNA sequencing, including Multiplex PCR assays detect whole-genome sequencing, multiple virulence factors provides comprehensive simultaneously, providing a genetic information for comprehensive picture of accurate identification. Klebsiella's virulence potential. Klebsiella Pneumoniae Subspecies Identification Klebsiella pneumoniae subsp. Klebsiella pneumoniae subsp. ozaenae pneumoniae Klebsiella pneumoniae subsp. pneumoniae is the most Klebsiella pneumoniae subsp. ozaenae is less common subspecies, responsible for various infections, commonly encountered, associated with chronic, foul- including pneumonia, urinary tract infections, and smelling nasal infections (ozena). bacteremia. It lacks the typical capsule produced by K. pneumoniae It produces a capsule that contributes to its virulence subsp. pneumoniae, which may explain its different and helps evade the host's immune system. clinical manifestations. Klebsiella Oxytoca Subspecies Identification Biochemical Testing Molecular Methods Antibiotic Susceptibility K. oxytoca can be distinguished from PCR assays targeting specific genes K. oxytoca is often more resistant to K. pneumoniae by its ability to can be used to confirm the antibiotics than K. pneumoniae. produce indole and its sensitivity to identification of K. oxytoca. the antibiotic colistin. Emerging Klebsiella Species and Variants Klebsiella pneumoniae Klebsiella oxytoca Klebsiella aerogenes Klebsiella pneumoniae is a leading Klebsiella oxytoca is commonly It is an opportunistic pathogen, cause of healthcare-associated found in the environment, commonly found in hospital infections. particularly in water. environments, and can cause infections in the respiratory tract, urinary tract, and bloodstream Diseases caused by Klebsiella 1. Klebsiella pneumoniae causing pneumonia 2. Klebsiella aerogenes cause urinary tract infection 3. Klebsiella rhinoscleromatis cause granuloma of mucous membrane of the nose Reporting and Interpretation of Results Colony Morphology and Microscopic Examination Antibiotic Susceptibility Growth Laboratory reports detail Klebsiella The report includes details about The report lists antibiotics tested colony characteristics, including Gram stain results, such as and their associated sensitivity or size, shape, color, and growth morphology, arrangement, and resistance patterns, providing patterns on specific media. presence of capsules. crucial information for treatment decisions.