Once organisms are grown in culture, hybridization, amplification, or RFLP analysis may be used to establish identity. Because the target nucleic acid is already amplified via microbial cultivation, sensitivity is not usually a problem for molecular identification methods. Addition ally, extensive nucleotide sequence data are available for most clinically relevant organisms, providing the required information to produce highly specific probes and primers. With neither specificity nor sensitivity as problems in this setting, other criteria regarding the application of molecular identification methods must be considered.

The criteria often considered in comparing molecular and conventional methods for microbial identification include speed, accuracy, and cost. For slow-growing organisms, such as mycobacteria and fungi, growth-based identification schemes can take weeks to months to produce a result. Molecular-based methods can identify these microorganisms almost immediately after sufficient inoculum is available, clearly demonstrating a speed advantage over conventional methods. Mycobacteria spp. may take up to several months to correctly identify. A molecular test is available that amplifies the DNA coding sequence for the 16s subunit of the rRNA, which is a genetic characteristic common to all species of mycobacteria. This provides a screening method indicating the presence of a Mycobacterium species. This procedure may then be followed by amplification of a insertion sequence (S6110) that is unique and specific for M. tuberculosis. Additional species may be identified using the differential restriction digestion patterns for the hsp65 gene present in all mycobacteria. On the other hand, phenotypic-based methods used to identify frequently encountered bacteria, such as S. aureus and beta-hemolytic streptococci, can usually provide highly accurate results within minutes and are less costly and time-consuming than any currently available molecular method. However, this is rapidly changing. Real-time PCR–based methods are commercially available for screening of MRSA upon admission to a long-term care or hospital facility. This identification provides for immediate isolation of carriers, preventing the spread of nosocomial infections throughout the facility.

Although many of the phenotype-based identification schemes are highly accurate and reliable, in some situations phenotypic profiles may yield uncertain identifications and molecular methods are providing an alternative for establishing a definitive identification. This is especially the case when a common pathogen exhibits unusual phenotypic traits (e.g., optochin-resistant Streptococcus pneumoniae).

اخر الاخبار

اخبار العتبة العباسية المقدسة

أكاديمية التطوير الإداري تقيم ورشة عن منهجية الإشراف الأكاديمي الفعّال على بحوث الطلبة

قسم الشؤونِ الخدمية يوفر ثلاثة آلاف صندوق أمانات لزائري مرقد أبي الفضل العباس (عليه السلام)

خلال عيد الفطر المبارك.. قسم الشؤون الدينية يضاعف جهوده للإجابة عن الاستفتاءات الشرعية للزائرين

قسم الشؤون الفكرية يقيم ندوةً ثقافية حول فوائد تشريع العيد في ذي قار

المزيد

الآخبار الصحية

كوب قبل النوم.. مشروب طبيعي يحارب الأرق

دون أدوية.. طريقة طبيعية لخفض ضغط الدم بفعالية مذهلة

المعكرونة ليست عدوك.. كيف تصبح جزءا من وجبة صحية متوازنة؟

دراسة: تناول القهوة يوميا يخفض خطر الإصابة بالاضطرابات النفسية

المزيد

الآخبار التكنلوجية

علماء روس يخططون لبناء منشأة للكشف عن المادة المظلمة

ثاني أكسيد الكربون ليس تهديدا للمناخ فقط.. بل لصحة الإنسان أيضا!

ديدان الأرض تكشف تلوث التربة بالمعادن الثقيلة

خبير أرصاد جوية: ظاهرة النينيو القادمة قد تكون الأقوى خلال 10 سنوات

المزيد

مواضيع ذات صلة

Direct Detection of Microorganisms

Laboratory Manifestations of Iron Overload

Differential Diagnosis of Iron Deficiency

Laboratory Manifestations of Iron Deficiency

Staining Techniques for Light Microscopy

Selection of Culture Media

Sterilization and Disinfection

Biochemical Assays for Metabolic Diseases

Laboratory Diagnosis of Urinary Tract Infections

Identification of Mycoplasma Infections

Laboratory Diagnosis of Infections of the Eyes

Laboratory Diagnosis of Central Nervous System Infections