MSc Med, Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences,University of the Witwatersrand, 2009 / Anaerobic bacteria cause serious life-threatening infections such as endocarditis, sepsis,
intra abdominal, pleuro-pulmonary and central nervous systems infections. Most infections
are polymicrobial and involve aerobes and anaerobes. Empiric therapy is generally based
on the expected pathogens and the particular type of infection. Even when specimens are
cultured and anaerobes identified, not all laboratories perform susceptibility testing. The
clinician often relies on published surveillance data when selecting treatment regimens.
Antimicrobial susceptibility of anaerobic bacteria is becoming increasingly unpredictable.
Resistance can vary significantly and patterns differ geographically, and even within units
of the same hospital.
From June 2005 until February 2007, 180 consecutive anaerobes isolated from relevant,
non- repetitive clinical specimens were tested routinely with the E test method for
susceptibility to amoxicillin/ clavulanate (XL), clindamycin (Cm), metronidazole (Mz),
penicillin (Pg), ertapenem (Etp), cefoxitin (Fx), ceftriaxone (Tx), chloramphenicol (Cl),
and piperacillin/tazobactam (Ptc). The results were read after 48hr incubation in anaerobic
conditions. Specimen distribution was as follows: abdominal fluid (3), abscess (7),
abdominal abscess (4), aspirates (3), blood cultures (27), bone (3), breast (3), drainage
fluid (2), empyema (1), fluids (36), other (4), placental (1), pleural fluid (2), pus (41),
tissues (34), umbilicus (1) and unknown sites (8).
Bacteroides fragilis was isolated from 81 (45%) clinically significant specimens, followed
by Clostridium perfringens 23 (13%), Peptostreptococcus anaerobius 15 (8%) and
Prevotella melaniniogenicus 15 (8%). B. fragilis demonstrated a 97.5% resistance to
penicillin and 12.3% resistance to metronidazole. C. perfringens exhibited no resistance to
penicillin and metronidazole while P. anaerobius had 40% resistance to penicillin and no
resistance to metronidazole. P. melaninogenicus was resistant to penicillin in 60% and
6.7% to metronidazole. Overall, chloramphenicol, piperacillin/tazobactam, ertapenem and
amoxicillin/clavulanate demonstrated the highest activity to anaerobic isolates, 100%,
99.4%, 97.2% and 96.7%, respectively. Among the 180 tested anaerobes a total of 8.9%
resistance has been observed with metronidazole and 81.7% sensitivity with clindamycin.
Periodic surveillance to monitor the susceptibility profile of the B. fragilis group and other
anaerobic organisms is recommended to create empirical guidelines for appropriate use of
antimicrobial agents.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/7987 |
| Date | 15 April 2010 |
| Creators | Naidoo, Sudeshni |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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