Incidence of fluoroquinolone-resistant and extended-spectrum ß-lactamase-producing Escherichia coli at a comprehensive cancer center in the United States.

BACKGROUND: Quinolones are used extensively for prophylaxis in high-risk cancer patients; however, increasing quinolone resistance is being reported. Extended-spectrum ß-lactamase (ESBL)-producing E. coli may be associated with increased morbidity and mortality particularly in neutropenic cancer patients. METHODS: We conducted a retrospective study of consecutive E. coli isolates from January 2009 to August 2009 at our institution. Data on antimicrobial susceptibility of E. coli isolates to commonly used antimicrobial agents and the frequency of ESBL production and fluoroquinolone resistance were gathered based on CLSI guidelines. RESULTS: There were 443 isolates of E. coli recovered. The majority were from urine cultures (308 isolates, 69.5%). Forty-one (9.2%) isolates were ESBL producing. Nine (18.3%) of the 49 isolates recovered from blood stream infections were ESBL producing. Quinolone resistance was present in 204 isolates (46%). Carbapenems and aminoglycosides retained excellent activity. E. coli resistance to quinolones increased from 13 to 46% in a period of 13 years (p = 0.001). CONCLUSION: The incidence of resistance to quinolones at our center may be increasing as a consequence of widespread use of quinolones as prophylaxis for neutropenic patients. ESBL-producing E. coli are frequent at our center and are associated with blood stream infections.

Changing trends in etiology of bacteremia in patients with cancer.

The present study was conducted to determine trends in the quantitative bacterial load patterns of bacterial bloodstream infections (BSI) caused by various bacteria in patients receiving care at a comprehensive cancer center. Bacterial loads of all consecutive quantitative blood cultures performed during 1998 and 2004 were graded quantitatively. Gram-positive bacteria (GPB) were responsible for the majority of BSI episodes in both years studied: 740 of 1,055 (73%) in 1998 and 820 of 1,025 (82%) in 2004. Compared with GPB infections, a significant proportion of infections caused by Gram-negative bacteria was associated with a high bacterial load (HBL) (11 vs 28% in 1998 and 10 vs 30% in 2004; p<0.001). In 2004, BSI episodes due to non-Pseudomonas non-fermentative GNB (Stenotrophomonas maltophilia and Acinetobacter spp) were significantly associated with a HBL compared to BSI due to Pseudomonas aeruginosa (47 vs 23%; p<0.05); this was not the case in 1998. Conversely, the HBLs commonly associated with BSI due to Staphylococcus aureus (50%) and Streptococcus spp (35%) versus coagulase-negative staphylococci (13%; p<0.0001) during 1998 were not noted during 2004 (22% Staphylococcus aureus, 20% Streptococcus spp, 21% coagulase-negative staphylococci; p>0.5). The spectrum of BSI continues to change and its prognostic implications in cancer patients needs further study.

Recent experience with Pseudomonas aeruginosa bacteremia in patients with cancer: Retrospective analysis of 245 episodes.

BACKGROUND: Pseudomonas aeruginosa bacteremia is a serious and possibly fatal condition in patients with cancer. OBJECTIVES: To ascertain the frequency, demographics, and predisposing factors for P. aeruginosa bacteremia in patients with cancer and to determine the efficacy of various therapeutic regimens. SUBJECTS AND METHODS: Patient records of the Clinical Microbiology Laboratory, The University of Texas, M. D. Anderson Cancer Center, Houston, were reviewed. From January 1, 1991, through December 31, 1995, 245 eligible cases of P. aeruginosa bacteremia were identified. We examined the patient records for the underlying malignant neoplasm and its management, symptoms and signs of infection, culture results of appropriate specimens, antibiotic therapy, and outcome. We also compared our present experience with a previous analysis from this institution covering the period from January 1, 1972, to December 31, 1981. RESULTS: The incidence of P. aeruginosa bacteremia has decreased compared with the previous study (2.8 vs 4.7 cases per 1000 admissions). It was most common in patients with acute leukemia (55 of 1000 registrations), and the frequency in this disease has not changed. Half of the patients were not in the hospital when they developed their infection. The overall cure rate was 80%, which was a significant (P<.001) increase compared with the 62% cure rate in the previous study. In this study, no significant difference in the cure rates was observed between monotherapy with a beta-lactam and combination therapy overall (P = .72), and in patients with shock (P = 1.0) and those with pneumonia (P = .60). The patients' initial neutrophil counts were not of prognostic value; however, the cure rate depended on subsequent changes in neutrophil count during therapy. CONCLUSIONS: The frequency rate of P. aeruginosa bacteremia has decreased in patients with solid tumors but has remained unchanged in patients with acute leukemia. Antibiotic regimens for empirical therapy of neutropenic patients and especially patients with acute leukemia should still provide coverage against P. aeruginosa.