Severe cellulitis/myositis caused by Stenotrophomonas maltophilia.
OBJECTIVE
To present a case of cellulitis/myositis due to Stenotrophomonas maltophilia in the absence of trauma and to discuss a potentially novel treatment option.


METHODS
A 57-year-old white man, having undergone an allogeneic bone marrow transplant, developed myositis with S. maltophilia of the left soleus muscle; there had been no trauma. Risk factors for infection included neutropenia, prolonged hospitalization and intensive care unit stay, and broad-spectrum antibiotic exposure. The affected area of muscle was resected and the patient successfully treated with trimethoprim/sulfamethoxazole (TMP/SMX), ticarcillin/clavulanate, and aztreonam.


CONCLUSIONS
In severe myositis/cellulitis caused by S. maltophilia, TMP/SMX is considered the drug of choice. However, bacteriostatic agents such as TMP/SMX are less than ideal in neutropenic patients. The combination of ticarcillin/clavulanate plus aztreonam has been shown to improve activity in vitro against this organism compared with TMP/SMX. This is likely due to inhibition of the 2 beta-lactamases this organism produces by clavulanate and aztreonam. In our study of clinical isolates of S. maltophilia, this combination reduced the minimum inhibitory concentration at 90% by 128-fold and was synergistic against 10 of 12 isolates tested in time-kill analysis.


CONCLUSIONS
S. maltophilia is emerging as an important pathogen in patients with compromised immunity, leading to severe infections that are difficult to treat. Based on in vitro synergy studied, we recommend considering ticarcillin/clavulanate plus aztreonam as a potential treatment option in immunocompromised patients with S. maltophilia infection.
Downhour
Nathan P
NP
Infectious Diseases Section, Department of Medicine, College of Medicine, University of Arizona, Tucson, AZ, USA.
Petersen
Eskild A
EA
Krueger
Todd S
TS
Tangella
Krishnarao V
KV
Nix
David E
DE
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001398:Aztreonam / Q000627:therapeutic use; D016026:Bone Marrow Transplantation / Q000009:adverse effects; D002481:Cellulitis / Q000188:drug therapy / Q000382:microbiology*; D019818:Clavulanic Acid / Q000627:therapeutic use; D004359:Drug Therapy, Combination / Q000627:therapeutic use; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008997:Monobactams / Q000627:therapeutic use; D018482:Muscle, Skeletal / Q000382:microbiology / Q000601:surgery; D009220:Myositis / Q000188:drug therapy / Q000382:microbiology*; D010406:Penicillins / Q000627:therapeutic use; D012307:Risk Factors; D020615:Stenotrophomonas maltophilia; D013982:Ticarcillin / Q000627:therapeutic use; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D008997:Monobactams; D010406:Penicillins; D019818:Clavulanic Acid; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D013982:Ticarcillin; D001398:Aztreonam