(b)
| Type of organism | No. of isolates | |
| 1987–1993 (n = 7) | 1994–2010 (n = 32) | |
| Gram-positive obligate anaerobes | ||
| Peptococcus species | — | 3 |
| Peptostreptococcus species | 3 | 11 |
| Gram-negative obligate anaerobes | ||
| Bacteroides fragilis | 1 | 3 |
| Veillonella | — | 1 |
| Total | 4 | 18 |
| Mixed anaerobic isolates | ||
| Peptostreptococcus + B. fragilis | — | 2 |
| Prevotella melaninogenicus + Peptostreptococcus | — | 1 |
| Total | — | 3 |
| Mixed aerobic and anaerobic isolates | ||
| Pseudomonas + B. fragilis + Peptostreptococcus | — | 2 |
| Strep. pneumonia + Proteus + B. fragilis | 1 | — |
| Pseudomonas +B. fragilis | — | 2 |
| S. aureus + Peptostreptococcus | — | 1 |
| Proteus + Peptostreptococcus | — | 2 |
| S. aureus + B. fragilis | 1 | 1 |
| BH Streptococci + B. fragilis | 1 | 1 |
| Pseudomonas +Veillonella | — | 1 |
| Veillonella+ Providencia stuartii | — | 1 |
| Total | 3 | 11 |