ABSTRACT
OBJECTIVE: To determine risk factors for patients whose cultures grew Stenotrophomonas maltophilia. DESIGN: Retrospective case-control study of 60 patients with cultures positive for S maltophilia, matched by specimen site to 120 controls whose cultures grew other gram-negative aerobic bacteria. SETTING: University medical center. RESULTS: S maltophilia was identified from the following sites: respiratory (36), wound (13), urinary (6), blood (4), and cerebral spinal fluid (1). By univariate analysis, cases had a higher risk of exposure than controls for ampicillin (P < .001), gentamicin (P < .001), vancomycin (P = .001), metronidazole (P = .003), piperacillin (P = .007), cefotaxime (P = .014), ceftazidime (P = .017), ciprofloxacin (P = .030), tobramycin (P = .040), and chronic respiratory disease (P = .024). Length of time foreign objects were in place prior to positive culture differed significantly between cases and controls only for endotracheal tubes in patients with respiratory isolates (median number of days: 12.5 for cases, 5 for controls; P = .007). For patients with urinary tract infections, having a urinary catheter increased the odds of infection 10 times over controls. Exposures found by multivariate analysis to be significantly more prevalent in cases than controls included ampicillin, cefotaxime, erythromycin, gentamicin, metronidazole, piperacillin, tobramycin, chronic respiratory disease, and female gender. Odds ratios were > 1 indicating higher risk for cases, except for erythromycin, which had an odds ratio < 1. CONCLUSIONS: The primary risk factor associated with isolation of S maltophilia was antibiotic use. For patients with pulmonary infections, chronic respiratory disease and length of time an endotracheal tube was in place also contributed to the risk. This suggests that judicious use of antibiotics may prevent some cases of S maltophilia infection.
Subject(s)
Community-Acquired Infections/epidemiology , Cross Infection/epidemiology , Drug Resistance, Multiple , Xanthomonas/isolation & purification , Adult , Anti-Bacterial Agents/adverse effects , California/epidemiology , Case-Control Studies , Chronic Disease , Community-Acquired Infections/blood , Community-Acquired Infections/urine , Confidence Intervals , Cross Infection/blood , Cross Infection/urine , Female , Humans , Intubation, Intratracheal/adverse effects , Logistic Models , Male , Matched-Pair Analysis , Multivariate Analysis , Odds Ratio , Respiratory Tract Diseases/complications , Risk Factors , Time FactorsABSTRACT
Gram-negative pathogens are increasingly resistant to extended-spectrum cephalosporins (ESCs). Using a prospective, case-controlled observational study, we examined the prevalence and the risk factors for development of resistance to ESCs in group I beta-lactamase-producing organisms. Of the 386 isolates of Enterobacter species, Pseudomonas aeruginosa, Citrobacter species, and Serratia marsescens from 340 consecutive patients, 70 (18.1%) were resistant to ESCs; the highest rates of resistance were found among Citrobacter freundii (40.9%), Enterobacter cloacae (31.1%), and Enterobacter aerogenes isolates (18.9%). Patients' prior antibiotic use and the mean number of antibiotics used were significantly greater in association with resistant vs. susceptible isolates. Resistance was associated with prior use of ceftizoxime or cefotaxime (P = .008), ceftazidime (P = .004), and piperacillin (P = .001). Other antibiotics were not associated with resistance. Resistance was less frequent in patients receiving ESCs and an aminoglycoside. We conclude that prior use of ESCs is associated with the isolation of resistant group I beta-lactamase-producing organisms. Concomitant use of an aminoglycoside may decrease this risk.
Subject(s)
Cephalosporins/pharmacology , Enterobacteriaceae/drug effects , Enterobacteriaceae/enzymology , beta-Lactamases/biosynthesis , Adult , Case-Control Studies , Citrobacter/drug effects , Cross Infection/drug therapy , Cross Infection/microbiology , Drug Resistance, Microbial , Enterobacter/drug effects , Enterobacteriaceae/isolation & purification , Enterobacteriaceae Infections/drug therapy , Enterobacteriaceae Infections/microbiology , Female , Humans , Male , Middle Aged , Prospective Studies , Pseudomonas aeruginosa/drug effects , Risk Factors , Serratia marcescens/drug effectsABSTRACT
Arbitrarily primed PCR (AP-PCR) was used to type 64 clinical isolates of Stenotrophomonas maltophilia from 60 patients and the hands of one nurse. Forty-seven different patterns were observed, most patients having isolates with unique genomic fingerprints. A single pattern, however, was obtained from six of eight patients involved in an intensive care nursery outbreak, confirming the suspected nosocomial transmission of this microorganism. This strain was also found in four other patients hospitalized at the same time but in different units. AP-PCR typing results had a good correlation with the 49 patterns obtained when the isolates were typed by contour-clamped homogeneous electric field gel electrophoresis. Although AP-PCR is slightly less discriminatory than contour-clamped homogeneous electric field gel electrophoresis, it offers several advantages and should be considered as a practical option for molecular typing during investigations of outbreaks.
