Initial processing of anaerobic specimens involves inoculation of appropriate media. Table 1 lists commonly used anaerobic media. Primary plates should be freshly prepared or used within 2 weeks of preparation. Plates stored for longer periods accumulate peroxides and become dehydrated; this results in growth inhibition. Reduction of media in an anaerobic environment eliminates dissolved oxygen but has no effect on the peroxides. Prereduced, anaerobically sterilized (PRAS) media are produced, packaged, shipped, and stored under anaerobic conditions. They are commercially available from Anaerobe Systems (Morgan Hill, California) (Figure 1) and have an extended shelf life of up to 6 months.

Table1. Common Anaerobic Media

Fig1. Prereduced, anaerobically sterilized (PRAS) plated  media. (Courtesy Anaerobe Systems, Morgan Hill, Calif.)

In general, anaerobic media should include a nonselective anaerobic blood agar and one or all of the following selective media: Bacteroides bile esculin agar (BBE), laked kanamycin-vancomycin blood agar (LKV), and anaerobic phenylethyl alcohol agar (PEA). In addition, aerobic 5% sheep blood agar, chocolate agar, and Mac Conkey agar are set up because most anaerobic infections are polymicrobic and may include aerobic or facultative anaerobic bacteria. A backup broth, usually thioglycollate, is inoculated to enrich small numbers of anaerobes in tissues and other sterile specimens. Most anaerobes grow well on any of the foregoing media.

Cultures for C. difficile are plated on a special selective medium, cycloserine cefoxitin fructose agar (CCFA) or egg yolk agar (EYA). There are also selective media for certain groups of anaerobes, such as Actinomyces spp., although they are rarely used in the clinical laboratory.

Special anaerobic blood culture systems containing various media, including thioglycollate broth, thiol broth, and Schaedler’s broth, are commercially available. Although many anaerobes will grow in the aerobic blood culture bottle, it is better to use an unvented anaerobic broth when attempting to isolate these organisms from blood or bone marrow.

INCUBATION CONDITIONS AND DURATION

 Inoculated plates should be immediately incubated under anaerobic conditions at 35° to 37°C for 48 hours. In general, cultures should not be exposed to oxygen until after 48 hours’ incubation, because anaerobes are most sensitive to oxygen during their log phase of growth. Plates may be removed from the anaerobic environment at 24 hours, briefly evaluated, and returned to the anaerobic environment. Plates incubated in an anaerobe chamber or bag can be examined at 24 hours without oxygen exposure for typical colonies of B. fragilis group or Clostridium perfringens. Plates that show no growth at 48 hours should be incubated for at least 5 days before being discarded.

Thioglycollate broth can be incubated anaerobically with the cap loose or anaerobically with the cap tight. Broths should be inspected daily for 7 days.

اخر الاخبار

اخبار العتبة العباسية المقدسة

تزامنًا مع حلول شهر ربيع الأول.. العتبة العباسية المقدسة ترفع مظاهر الحزن والسواد في المرقد الطاهر

بعد انتهاء شهري المحرم وصفر.. قسم الصيانة يباشر إدامة الثريات واستبدال مصابيح المرقد الطاهر

قسم الشؤون الخدمية يشرع بإدامة آليّات النظافة عقب انتهاء زيارة الأربعين

موكب عزاء الشعراء والرواديد ينظم مسيرة عزائية في ختام شهري الأحزان المحرم الحرام وصفر

المزيد

الآخبار الصحية

العنب.. فاكهة صغيرة بمفعول "خارق" للقلب والدماغ

دراسة تحدد "الحلقة المفقودة".. تسبب ارتفاع ضغط الدم

هذه الأطعمة تحمي دماغك من الشيخوخة وتزيد حدة الذكاء

خبراء يحذرون من مخاطر "الدهون المخفية" على القلب

المزيد

الآخبار التكنلوجية

الأرصاد الجوية تلجأ إلى الذكاء الاصطناعي.. لأي غرض؟

في منزلك.. "تعديل بسيط" يخفض ضغط الدم بشكل طبيعي

"ميزة جديدة" من إنستغرام تنافس تيك توك.. طال انتظارها

غوغل في مأزق.. بيانات 2.5 مليار مستخدم بقبضة القراصنة

المزيد

مواضيع ذات صلة

Specimen Processing of Anaerobic Bacteriology

Specimen Collection and Transport of Anaerobic Bacteriology

Gonococcal Arthritis

Nongonococcal Bacterial Arthritis

Acute Bacterial Arthritis

Streptococcus pyogenes

Treatment of Staphylococci

Enzymes and Toxins of Staphylococci

Rocky Mountain Spotted Fever

Human Ehrlichiosis

Antimicrobial Susceptibility Testing and Therapy of Neisseria and Moraxella catarrhalis

Laboratory Diagnosis of Neisseria and Moraxella catarrhalis