Monotherapy with minocycline or trimethoprim/sulfamethoxazole for treatment of Stenotrophomonas maltophilia infections

Intraabdominal abscess caused by Stenotrophomonas maltophilia: A case report

INTRODUCTION

Stenotrophomonas maltophilia usually causes nosocomial infections, but intraabdominal abscesses or organ/space surgical site infection (SSI) secondary to this organism has been rarely reported. Here, we reported a rare case of SSI that presented as intraabdominal abscess caused by S. maltophilia.

PRESENTATION OF CASE

A 68-year-old woman presented to our hospital with transverse colon cancer. Further work up with abdominal computed tomography (CT) revealed left renal cell carcinoma. Transverse colon resection and left kidney partial resection were performed. On post-operative day 10, she started to have fever at 38°C and repeat abdominal CT showed intraabdominal abscess. Empiric treatment with piperacillin/tazobactam (TAZ/PIPC) was initiated. However, fever persisted and the abscess size did not change despite 10 days of antibiotic. On post-operative day 20, drainage of intraabdominal abscess was performed. TAZ/PIPC was then shifted to meropenem (MEPM). After two days, S. maltophilia was identified in the culture of the abscess, and MEPM was shifted to minocycline (MINO). Fever disappeared after 7days of treatment and abdominal CT after 14 days showed almost complete resolution of the abscess.

DISCUSSION

S. maltophilia is a multi-drug resistant, aerobic, non-glucose fermenting, non-sporulating, Gram-negative bacillus. S. maltophilia may cause a variety of infections, but intraabdominal abscesses as a manifestation of SSI due to this organism is relative rare.

CONCLUSION

Although usually a non-pathogenic organism or colonizer, S. maltophilia can cause organ/space SSI in an immunocompromised host. Therefore, clinicians should be aware of the possibility that S. maltophilia may cause organ/space SSI.

Comparison of the therapeutic efficacy of fluoroquinolone and non-fluoroquinolone treatment in patients with Elizabethkingia meningoseptica bacteraemia

Elizabethkingia meningoseptica is a non-fermentative Gram-negative bacillus that has emerged as an important pathogen in nosocomial infections and is usually associated with high mortality. E. meningoseptica is inherently resistant to many broad-spectrum antibiotics, and appropriate antibiotic selection is crucial for survival. Data about the therapeutic efficacy of fluoroquinolone in E. meningoseptica bacteraemia are limited. We retrospectively enrolled patients with E. meningoseptica bacteraemia who were treated with a single antimicrobial agent with in vitro activity against E. meningoseptica for at least 48 hours in a Taiwanese medical centre between January 2011 and June 2016. We compared the therapeutic efficacy of fluoroquinolone and non-fluoroquinolone treatment. A logistic regression and a propensity score-adjusted model were used to evaluate the risk factors for 14-day mortality. A total of 66 patients were identified, 24 who received fluoroquinolone treatment (ciprofloxacin, n = 9; levofloxacin, n = 15) and 42 who received non-fluoroquinolone treatment (piperacillin/tazobactam, n = 26; trimethoprim/sulfamethoxazole, n = 15; minocycline, n = 1). The fluoroquinolone group had significantly lower 14-day mortality than the non-fluoroquinolone group (8.3% vs. 33.3%, P = 0.023). The APACHE II score was significantly higher in the non-fluoroquinolone group than in the fluoroquinolone group. In a propensity-adjusted analysis, fluoroquinolone use was an independent factor associated with 14-day survival. After stratification using the APACHE II score, treatment with fluoroquinolone was associated with 14-day survival, but did not reach statistical significance in both groups with greater and lesser severity. Therefore, fluoroquinolone is a suitable antimicrobial agent for treating E. meningoseptica bacteraemia.

The growing threat of multidrug-resistant Gram-negative infections in patients with hematologic malignancies

Prolonged neutropenia and chemotherapy-induced mucositis render patients with hematologic malignancies highly vulnerable to Gram-negative bacteremia. Unfortunately, multidrug-resistant (MDR) Gram-negative bacteria are increasingly encountered globally, and current guidelines for empirical antibiotic coverage in these patients may not adequately treat these bacteria. This expansion of resistance, coupled with traditional culturing techniques requiring 2-4 days for bacterial identification and antimicrobial susceptibility results, have grave implications for these immunocompromised hosts. This review characterizes the epidemiology, risk factors, resistance mechanisms, recommended treatments, and outcomes of the MDR Gram-negative bacteria that commonly cause infections in patients with hematologic malignancies. We also examine the infection prevention strategies in hematology patients, such as infection control practices, antimicrobial stewardship, and targeted decolonization. Finally, we assess the strategies to improve outcomes of the infected patients, including gastrointestinal screening to guide empirical antibiotic therapy, new rapid diagnostic tools for expeditious identification of MDR pathogens, and use of two new antimicrobial agents, ceftolozane/tazobactam and ceftazidime/avibactam.

Evaluation of Trimethoprim/Sulfamethoxazole (SXT), Minocycline, Tigecycline, Moxifloxacin, and Ceftazidime Alone and in Combinations for SXT-Susceptible and SXT-Resistant Stenotrophomonas maltophilia by In Vitro Time-Kill Experiments

Background

The optimal therapy for infections caused by Stenotrophomonas maltophilia (S. maltophilia) has not yet been established. The objective of our study was to evaluate the efficacy of trimethoprim/sulfamethoxazole (SXT), minocycline, tigecycline, moxifloxacin, levofloxacin, ticarcillin-clavulanate, polymyxin E, chloramphenicol, and ceftazidime against clinical isolated S. maltophilia strains by susceptibility testing and carried out time-kill experiments in potential antimicrobials.

Methods

The agar dilution method was used to test susceptibility of nine candidate antimicrobials, and time-killing experiments were carried out to evaluate the efficacy of SXT, minocycline, tigecycline, moxifloxacin, levofloxacin, and ceftazidime both alone and in combinations at clinically relevant antimicrobial concentrations.

Results

The susceptibility to SXT, minocycline, tigecycline, moxifloxacin, levofloxacin, ticarcillin-clavulanate, chloramphenicol, polymyxin E, and ceftazidime were 93.8%, 95.0%, 83.8%, 80.0%, 76.3%, 76.3%, 37.5%, 22.5%, and 20.0% against 80 clinical consecutively isolated strains, respectively. Minocycline and tigecycline showed consistent active against 22 SXT-resistant strains. However, resistance rates were high in the remaining antimicrobial agents against SXT-resistant strains. In time-kill experiments, there were no synergisms in most drug combinations in time-kill experiments. SXT plus moxifloxacin displayed synergism when strains with low moxifloxacin MICs. Moxifloxacin plus Minocycline and moxifloxacin plus tigecycline displayed synergism in few strains. No antagonisms were found in these combinations. Overall, compared with single drug, the drug combinations demonstrated lower bacterial concentrations. Some combinations showed bactericidal activity.

Conclusions

In S. maltophilia infections, susceptibility testing suggests that minocycline and SXT may be considered first-line therapeutic choices while tigecycline, moxifloxacin, levofloxacin, and ticarcillin-clavulanate may serve as second-line choices. Ceftazidime, colistin, and chloramphenicol show poor active against S. maltophilia. However, monotherapy is inadequate in infection management, especially in case of immunocompromised patients. Combination therapy, especially SXT plus moxifloxacin, may benefit than monotherapy in inhibiting or killing S. maltophilia.