Comparison of two schedules of cefoperazone plus aztreonam in the treatment of neutropenic patients with fever

Cancer patients were randomized to receive an every 4 hour or every 8 hour schedule of cefoperazone plus aztreonam during 617 febrile episodes. The overall response rate for the 478 evaluable episodes was 76 % and there was no difference in response rate between the two schedules. The response rate was 79 % for cases of pneumonia and 63 % for cases of bacteremia. Only 50 % of the microbiologically documented infections caused by gram-positive organisms responded whereas 95 % of gram-negative infections, including all of those caused byPseudomonas aeruginosa, responded. Response rates were lower among patients whose neutrophil counts decreased during therapy than among those whose neutrophil counts increased (64 % vs. 85 %, p=0.008). Side-effects that were possibly or probably related to antibiotic therapy were observed during 11 % of the episodes. The most common side-effects were diarrhea and rashes including one case of Stevens-Johnson syndrome. Three patients developed a coagulopathy during therapy. Cefoperazone plus aztreonam proved to be an effective combination for treatment of gram-negative infections and fever of unknown origin in cancer patients and an every 8-hour schedule of administration was as effective as an every 4-hour schedule. Approximately half of the patients with gram-positive infections required additional antibiotics for successful therapy.     

Pseudomonas aeruginosa Bacteremia in Patients Infected with Human Immunodeficiency Virus Type 1

 A prospective analysis of 43 episodes of Pseudomonas aeruginosa bacteremia in HIV-1-infected subjects was performed and the results compared with the incidence and outcome of Pseudomonas aeruginosa bacteremia in other high-risk patients, such as transplant recipients, leukemia patients, or patients hospitalized in the intensive care unit. The incidence of bacteremia/fungemia as a whole and of gram-negative and Pseudomonas aeruginosa bacteremia in particular was greater in HIV-1-infected subjects than in the unselected general population admitted. In contrast, the incidence of Pseudomonas aeruginosa bacteremia in HIV-1-infected patients did not differ from that in patients with other high-risk conditions. In patients with HIV-1 infection, independent risk factors for presenting Pseudomonas aeruginosa bacteremia were nosocomial origin (OR, 2.7; 95% CI, 1.3–5.7), neutropenia (OR, 2.7; 95% CI, 1.07–6.8), previous treatment with cephalosporins (OR, 3.6; 95% CI, 1.1–11.6), and a CD4+ cell count lower than 50 cells/mm³ (OR, 3.1; 95% CI, 1.7–8.6). Primary bacteremia and pneumonia were the most common forms of presentation. Fourteen (33%) patients died as a consequence of the bacteremia. The presence of severe sepsis (OR, 17.5; 95% CI, 3.2–68) and the institution of inappropriate definitive antibiotic therapy (OR, 2.7; 95% CI, 1.1–13) were independently associated with a poor outcome. One year after the development of bacteremia, only eight (19%) patients remained alive.     

Prevalence and Drug Susceptibility of Pathogens Causing Bloodstream Infections in Northern Italy: A Two-Year Study in 16 Hospitals

The epidemiology of bacterial pathogens causing bloodstream infection was studied in 16 hospitals in Lombardy (northern Italy) over a 2-year period (1999 and 2000). Overall, 2,924 microorganisms causing significant bacteremia were collected. The most frequent isolates were Escherichia coli (n=663; 22.7%), Staphylococcus aureus (n=534; 18.3%), Staphylococcus epidermidis (n=242; 8.2%), and Pseudomonas aeruginosa (n=176; 6.0%). Unlike Escherichia coli, which was usually acquired from the community, Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa were usually acquired in hospitals. Rates of resistance to oxacillin and its associated traits were significantly higher among hospital-acquired staphylococci as compared to those of isolates from the community. Escherichia coli was highly susceptible to extended-spectrum cephalosporins, with a very low percentage of strains producing extended-spectrum ?-lactamases (ESBLs). On the contrary, production of ESBL appeared to be an important mechanism of resistance among nosocomial isolates of Klebsiella pneumoniae. Resistance to ciprofloxacin was widespread in several members of the family Enterobacteriaceae, with rates often exceeding 10%. Moreover, with regard to ciprofloxacin, there were no significant differences between rates of resistance among Enterobacteriaceae causing hospital-acquired infections versus those causing community-acquired infections. Multidrug resistance was commonly observed in Pseudomonas aeruginosa, indicating the need for new antimicrobial agents that are more active against nonfermentative gram-negative bacteria. In conclusion, epidemiological studies of the prevalence and antimicrobial susceptibility patterns of blood isolates in northern Italy appear to provide useful information for both empirical treatment of suspected infections and better management of patients. Electronic Publication     

Impact of healthcare-associated acquisition on community-onset Gram-negative bloodstream infection: a population-based study

We performed a population-based study to examine the influence of healthcare-associated acquisition on pathogen distribution, antimicrobial resistance, short- and long-term mortality of community-onset Gram-negative bloodstream infections (BSI). We identified 733 unique patients with community-onset Gram-negative BSI (306 healthcare-associated and 427 community-acquired) among Olmsted County, Minnesota, residents from 1 January 1998 to 31 December 2007. Multivariate logistic regression was used to examine the association between healthcare-associated acquisition and microbiological etiology and antimicrobial resistance. Multivariate Cox proportional hazards regression was used to evaluate the influence of the site of acquisition on mortality. Healthcare-associated acquisition was predictive of Pseudomonas aeruginosa (odds ratio [OR] 3.14, 95% confidence intervals [CI]: 1.59–6.57) and the group of Enterobacter, Citrobacter, and Serratia species (OR 2.23, 95% CI: 1.21–4.21) as causative pathogens of community-onset Gram-negative BSI. Healthcare-associated acquisition was also predictive of fluoroquinolone resistance among community-onset Gram-negative bloodstream isolates (OR 2.27, 95% CI: 1.18–4.53). Healthcare-associated acquisition of BSI was independently associated with higher 28-day (hazard ratio [HR] 3.73, 95% CI: 2.13–6.93) and 1-year mortality (HR 3.60, 95% CI: 2.57–5.15). Because of differences in pathogen distribution, antimicrobial resistance, and outcomes between healthcare-associated and community-acquired Gram-negative BSI, identification of patients with healthcare-associated acquisition of BSI is essential to optimize empiric antimicrobial therapy.     

Antimicrobial Susceptibility Trends and Risk Factors for Antimicrobial Resistance in Pseudomonas aeruginosa Bacteremia: 12-Year Experience in a Tertiary Hospital in Korea

BackgroundInfections caused by multidrug-resistant Pseudomonas aeruginosa (MDRPA) have been on the rise worldwide, and delayed active antimicrobial therapy is associated with high mortality. However, few studies have evaluated increases in P. aeruginosa infections with antimicrobial resistance and risk factors for such antimicrobial resistance in Korea. Here, we analyzed changes in antimicrobial susceptibility associated with P. aeruginosa bacteremia and identified risk factors of antimicrobial resistance.MethodsThe medical records of patients with P. aeruginosa bacteremia who were admitted to a tertiary hospital between January 2009 and October 2020 were retrospectively reviewed. Antibiotic resistance rates were compared among the time periods of 2009–2012, 2013–2016, and 2017–2020 and between the intensive care unit (ICU) and non-ICU setting. Empirical antimicrobial therapy was considered concordant, if the organism was susceptible to antibiotics in vitro, and discordant, if resistant.ResultsDuring the study period, 295 patients with P. aeruginosa bacteremia were identified. The hepatobiliary tract (26.8%) was the most common primary site of infection. The rates of carbapenem-resistant P. aeruginosa (CRPA), MDRPA, and extensively drug-resistant P. aeruginosa (XDRPA) were 24.7%, 35.9%, and 15.9%, respectively. XDRPA showed an increasing trend, and CRPA, MDRPA, and XDRPA were also gradually increasing in non-ICU setting. Previous exposure to fluoroquinolones and glycopeptides and urinary tract infection were independent risk factors associated with CRPA, MDRPA, and XDRPA. Previous exposure to carbapenems was an independent risk factor of CRPA. CRPA, MDRPA, and XDRPA were associated with discordant empirical antimicrobial therapy.ConclusionThe identification of risk factors for antimicrobial resistance and analysis of antimicrobial susceptibility might be important for concordant empirical antimicrobial therapy in patients with P. aeruginosa bacteremia.     

Clinical Significance of Polymicrobial Versus Monomicrobial Bacteremia Involving Pseudomonas aeruginosa

 The objective of this study was to examine the clinical significance of polymicrobial bacteremia involving Pseudomonas aeruginosa. Two hundred forty-eight episodes of Pseudomonas aeruginosa bacteremia, 43 of which were polymicrobic, were studied prospectively over a 6-year period. Three sets of blood cultures were obtained for each patient. Positive results for all three blood cultures were found more frequently in patients with polymicrobial infection, who were older than those with monomicrobial infection. Patients with polymicrobial bacteremia also were worse clinically and developed shock more frequently. Crude mortality was higher in patients with polymicrobial infection. A multivariate analysis revealed three variables significantly and independently associated with polymicrobial Pseudomonas aeruginosa bacteremia: higher age, poor clinical status of the patient, and positive results for all blood cultures obtained.     

Sources and outcome of bloodstream infections in cancer patients: the role of central venous catheters

Simultaneously drawn quantitative blood cultures are used to diagnose catheter-related bloodstream infections. We conducted this study to determine the frequency with which central venous catheters were the source of bloodstream infections detected through paired positive blood cultures drawn from cancer patients and the potential for quantitative blood cultures to help predict outcome in neutropenic and non-neutropenic patients. From September 1999 to November 2000, we identified 169 patients with bloodstream infections. Of all bloodstream infections, 56% were catheter-related bloodstream infections. Gram-positive bacteremia was found to be catheter-related in 55% and 69% of patients with hematologic malignancy and solid tumors, respectively, whereas gram-negative bacteremia was catheter-related in only 19% of patients with underlying hematologic malignancy and in 60% of patients with solid tumor (P = 0.01). By multivariate analysis, poor response was associated with critical illness and persistent neutropenia (P < 0.01). In neutropenic patients with catheter-related bloodstream infections, peripheral quantitative blood cultures of ≥100 CFU/mL was also associated with poor response (P = 0.05). Central venous catheters were the major source of bloodstream infection, particularly in patients with solid tumors. In addition to critical illness and persistent neutropenia, quantitative blood cultures might be useful in predicting outcomes for neutropenic patients with catheter-related bloodstream infections.     

In vitro activity of FK-037, a novel parenteral cephalosporin,against bacterial isolates from neutropenic cancer patients

The in vitro activity of FK-037, a novel parenteral cephalosporin, was compared to that of ceftazidime, aztreonam and piperacillin (agents often used in empiric regimens in cancer patients) against recent bacterial isolates from patients with cancer. FK-037 was either equal to or 2 to 16-fold more active than the comparative agents against members of theEnterobacteriaceae. It was also active againstAcinetobacter spp.,Aeromonas spp.,Pseudomonas aeruginosa, and otherPseudomonas spp.Xanthomonas maltophilia andAlcaligenes denitrificans were relatively resistant to all four agents. FK-037 was also 4 to 16-fold more active against most gram-positive organisms (including some methicillin-resistant staphylococci) than was ceftazidime.Enterococcus spp.,Listeria monocytogenes andStaphylococcus haemolyticus were relatively resistant to FK-037 and ceftazidime. Overall, FK-037 has a broad antimicrobial spectrum that includes the majority of gram-positive and gram-negative isolates.     

The importance of a judicious and early empiric choice of antimicrobial for methicillin-resistant Staphylococcus aureus bacteraemia

The purpose of this investigation was to examine the impact of antimicrobial regimens administered for hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia on the all-cause, 14-day mortality. We retrospectively examined the characteristics of the most effective empiric antimicrobial therapy in 87 consecutive patients, hospitalised at a single institution between April 2003 and March 2008, who presented with clinically and microbiologically confirmed MRSA bacteraemia. The all-cause mortality was measured 14 days after the diagnosis was made. The administration of an effective antimicrobial against MRSA <48 h after the collection of blood cultures was the single, significant predictor of survival (odds ratio 3.85; 95% confidence interval 1.37–10.80; p = 0.01). The survival of patients treated with vancomycin versus other antimicrobial agents was similar. Among subgroups treated with vancomycin, the lowest mortality (6%) was observed among patients treated (a) within 48 h after the collection of blood cultures and (b) with doses sufficient to keep the blood concentrations in the area under the 0–24 h curve >400 μg h/ml (≥2.0 g/day). The empiric administration of antimicrobials effective against MRSA bacteraemia within 48 h after the collection of blood cultures increased the 14-day survival. If vancomycin is chosen, ≥2.0 g/day should be administered, starting within 48 h.     

Delay in Administering the First Dose of Antibiotics in Patients Admitted to Hospital with Serious Infections

 The interval from the time of admission to the emergency room until the administration of antibiotics in patients presenting with a serious infectious disease was analysed. Fifty patients presumptively diagnosed in the emergency room as having a serious infection (respiratory tract, urinary tract, erysipelas, fever with neutropenia or bacteremia) needing immediate empirical antibiotic treatment were enrolled in the study. A median interval from time of admission to administration of antibiotics of 5 hours was determined (range 0.6–13.3 h). The interval was significantly shorter in patients admitted at night than in patients admitted during office hours (3.7 vs. 6.0 h, P<0.05). There was no difference with respect to the presenting features, body temperature, laboratory values at presentation or number of cultures performed. In 41 of the 50 patients blood samples were taken for culture. More than 80% of the patients received an antibiotic chosen in accordance with hospital guidelines. The analysis revealed that the median delay of 5 hours before patients received their initial dose of antibiotic depended on several factors. Attempts to provide optimal antimicrobial therapy should thus concentrate not only on the correct choice and dosage of a drug but also on prompt institution of therapy.     

Twenty-five year review ofPseudomonas aeruginosa bacteremia in a burn center

The incidence ofPseudomonas aeruginosa bacteremia was examined in 5,882 burn patients consecutively admitted over a 25-year period to one burn center. The population examined had an average burn size of 33.8 % of the body surface and an average age of 26.3 years.Pseudomonas aeruginosa bacteremia occurred in 540 patients. These patients had an average burn size of 54.2 % and average age of 28 years. Mortality was 77 %. Bacteremia with other organisms occurred during hospitalization of all but 128 of the 540 patients. Comparison of predicted mortality based on burn size and age to observed mortality showedPseudomonas aeruginosa bacteremia to be associated with a 28 % increase in mortality. Examination of mortality as a function of time showed no significant change over the 25-year period. The incidence ofPseudomonas aeruginosa colonization and infection was examined in 400 recently admitted burn patients. Colonization occurred in 107 and 34 infections were recorded in 27 of the colonized patients.     

Rates,predictors and mortality of community-onset bloodstream infections due to Pseudomonas aeruginosa: systematic review and meta-analysis

BackgroundPseudomonas aeruginosa is mostly a nosocomial pathogen affecting predisposed patients. However, community-onset bloodstream infections (CO-BSI) caused by this organism are not exceptional.ObjectivesTo assess the predisposing factors for CO-BSI due to P. aeruginosa (CO-BSI-PA) and the impact in mortality of inappropriate empirical antimicrobial therapy.Data sourceA systematic literature search was performed in the Medline, Embase, Cochrane Library, Scopus and Web of Science databases.Study eligibility criteria and participants: Articles published between 1 January 2002 and 31 January 2018 reporting at least of 20 adult patients with CO-BSI due to P. aeruginosa were considered.InterventionEmpiric antimicrobial therapy for CO-BSI-PA.MethodsA systematic review and a meta-analysis were conducted for risk factors and to evaluate if inappropriate empiric antimicrobial therapy increased mortality in CO-BSI-PA using a Mantel-Haenszel effects model.ResultsTwelve studies assessing data of 1120 patients were included in the systematic review. Solid tumour (33.1%), haematologic malignancy (26.4%), neutropenia (31.7%) and previous antibiotic use (44.8%) were the most prevalent predisposing factors. Septic shock was present in 42.3% of cases, and 30-day crude mortality was 33.8%. Mortality in meta-analysis (four studies) was associated with septic shock at presentation (odds ratio, 22.31; 95% confidence interval, 3.52–141.35; p 0.001) and with inappropriate empiric antibiotic therapy (odds ratio, 1.83; 95% confidence interval, 1.12–2.98l p 0.02).ConclusionsCO-BSI-PA mostly occurred in patients with predisposing factors and had a 30-day mortality comparable to hospital-acquired cases. Inappropriate empirical antibiotic therapy was associated with increased mortality. Appropriate identification of patients at risk for CO-BSI-PA is needed for empirical treatment decisions.     

Rhodococcus equi and Nocardia brasiliensis Infection of the Brain and Liver in a Patient with Acute Nonlymphoblastic Leukemia

 Resolution of neutropenia is usually followed by resolution of fever in patients with febrile neutropenia. However, in some cases fever continues even when the patient is no longer neutropenic. Described here is a case of acute myeloblastic leukemia complicated by brain abscess, pulmonary nodules, and hepatic lesions. The patient's fever had continued after the neutropenia resolved; brain and hepatic cultures grew Rhodococcus equi and Nocardia brasiliensis. Although Rhodococcus infections occur frequently in patients with HIV infection, they are uncommon in patients with acute leukemia.     

Antimicrobial combination treatment including ciprofloxacin decreased the mortality rate of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> bacteraemia: a retrospective cohort study

Ineffective antimicrobial therapy of Pseudomonas aeruginosa bacteraemia increases mortality. Recent studies have proposed the use of antimicrobial combination therapy composed of a beta-lactam with either ciprofloxacin or tobramycin. To determine if combination therapy correlates to lower mortality and is superior compared to monotherapy, we investigated the effect of antimicrobial treatment regimens on 30-day mortality in a cohort with Pseudomonas aeruginosa bacteraemia. All cases of P. aeruginosa bacteraemia (n?=?292) in southwest Skåne County, Sweden (years 2005–2010, adult population 361,112) and the whole county (2011–2012, 966,130) were identified. Available medical and microbiological records for persons aged 18 years or more were reviewed (n?=?235). Antimicrobial therapy was defined as empiric at admission or definitive after culture results and was correlated to 30-day mortality in a multivariate regression model. The incidence and mortality rates were 8.0 per 100,000 adults and 22.9% (67/292), respectively. As expected, multiple comorbidities and high age were associated with mortality. Adequate empiric or definitive antipseudomonal treatment was associated with lower mortality than other antimicrobial alternatives (empiric p?=?0.02, adj. p?=?0.03; definitive p?<?0.001, adj. p?=?0.007). No difference in mortality was seen between empiric antipseudomonal monotherapy or empiric combination therapy. However, definitive combination therapy including ciprofloxacin correlated to lower mortality than monotherapy (p?=?0.006, adj. p?=?0.003), whereas combinations including tobramycin did not. Our results underline the importance of adequate antipseudomonal treatment. These data also suggest that P. aeruginosa bacteraemia should be treated with an antimicrobial combination including ciprofloxacin when susceptible.     

Respiratory viruses,a common microbiological finding in neutropenic children with fever

BackgroundFebrile neutropenia is a common complication in children undergoing chemotherapy for malignancies. A microbial agent is only identified in 15–30% of the fever episodes and corresponds mostly to bacterial findings.ObjectiveTo investigate viral infections as possible etiologic agents in episodes of febrile neutropenia.Study designNasopharyngeal aspirates (NPAs) from patients presenting with neutropenic fever at two pediatric oncology wards in Sweden and Australia were analyzed with a conventional virus-diagnostic approach and RT-PCR. Coupled blood samples were analyzed for the detection of CMV, EBV, adenovirus and erythrovirus. Bacterial blood culture was performed routinely.ResultsConventional virus-diagnostic approach coupled to routinely performed bacterial analyzes revealed an infectious agent in 29% compared to 60% when using PCR. By adding PCR, a viral pathogen was detected in 46% of the NPAs and in 4% of the blood samples collected. In half of the patients with bacteremia, respiratory tract viruses were co-detected.ConclusionRespiratory viruses were frequently detected in NPAs suggesting a significant role of viral infections in children presenting with neutropenic fever. The meaning of these findings needs to be further evaluated but has the potential to individualize infection treatment and to reduce the extensive use of antibiotics in immunocompromised children with neutropenia.     

Prognostic Evaluation of Bacteremia and Fungemia in Patients with Acquired Immunodeficiency Syndrome

The incidence of bacterial infections in general and of bacteremia in particular is high among patients with acquired immunodeficiency syndrome (AIDS). The factors influencing the prognosis of bacteremia in these patients are not well known. In order to better define those factors associated with a poor prognosis, all episodes of bacteremia or fungemia in patients with AIDS who were hospitalized in four general hospitals between 1 September 1987 and 31 December 1996 were studied prospectively. Among 1,390 patients diagnosed with AIDS, 238 (17.1%) developed 274 episodes of bacteremia or fungemia. Mortality related to bacteremia was 21.3%. Variables associated with high mortality were fungemia (odds ratio [OR], 6.19; 95% confidence interval [CI], 1.99–19.28), hypotension (OR, 19.65; 95%CI, 7.42–52.07), inappropriate antimicrobial treatment (OR, 16.94; 95%CI, 4.92–58.32), and unknown origin of bacteremia (OR, 3.93; 95%CI, 1.58–9.76). The mortality rate among patients with at least one of these factors was 46.7%, whereas in patients without any of these factors, the rate was 4.9% (P<0.001). Bacteremic episodes of unknown origin were significantly more frequently associated with community acquisition (P=0.001), inappropriate antimicrobial treatment (P=0.04), and etiology by gram-negative microorganisms or fungi (P<0.001) and were significantly less frequently associated with the presence of a previous intravenous catheter (P=0.004), resulting in peculiar etiologic and epidemiological profiles. The factors that influence the outcome of AIDS patients who develop bacteremia are sometimes avoidable or known during the first days after admission. Therefore, knowledge about these factors could improve the prognosis of bloodstream infections in this population. Electronic Publication     

Development of early neutropenic fever, with or without bacterial infection, is still a significant complication after reduced-intensity stem cell transplantation.

Little information is available on the clinical characteristics of infectious complications that occur in the early period after reduced-intensity stem cell transplantation (RIST). We retrospectively investigated the clinical features of neutropenic fever and infectious episodes within 30 days after RIST in 76 patients who had received fluoroquinolones as part of their antibacterial prophylaxis. Preparative regimens included cladribine 0.66 mg/kg or fludarabine 180 mg/m2 plus busulfan 8 mg/kg. All but 1 patient survived 30 days after transplantation, and 75 patients (99%) became neutropenic within a median duration of 9 days. Neutropenic fever was observed in 29 patients (38%), and bacterial infection was confirmed in 15 (20%) of these, including bacteremia (n = 13), bacteremia plus pneumonia (n = 1), and urinary tract infection (n = 1). The causative organisms were gram-positive (n = 9) and gram-negative organisms (n = 7), with a mortality rate of 6%. Neither viral nor fungal infection was documented. Multivariate analysis showed that the presence of neutropenia at the initiation of preparative regimens was an independent risk factor for subsequent documented bacterial infections (P =.026; 95% confidence interval, 1.25-35.1). We conclude that neutropenic fever and bacteremia remain common complications in RIST.     

Value of measurement of C-reactive protein in febrile patients with hematological malignancies

The maximum serum levels of C-reactive protein (CRP) in 126 patients with hematological malignancies who had 554 febrile episodes were analyzed retrospectively with regard to documented infections and fever of unknown origin. The CRP levels were significantly higher when the blood culture was positive than when it was negative (p=0.002). The CRP levels were significantly higher when the infection focus was identified than when it was not (p=0.010). In patients with fever of unknown origin the CRP was significantly lower than in patients with microbiologically documented infections (p<0.001). Cytotoxic treatment neither reduced nor enhanced the CRP reaction. The serial measurement of CRP is a reliable and readily available means for differentiating between bacterial infections and other causes of fever in patients with hematological malignancies, also during neutropenia and after cytotoxic treatment.     

Persistence of a Multidrug-Resistant Pseudomonas aeruginosa Clone in an Intensive Care Burn Unit

Long-term colonization of various body sites with a multidrug-resistant Pseudomonas aeruginosa clone (resistant to piperacillin, cefoperazone, ceftazidime, aztreonam, imipenem, cefepime, cefpirome, ofloxacin, ciprofloxacin, minocycline, and aminoglycosides) with subsequent severe infections in burn patients has not been reported previously. Thirty-nine isolates of multidrug-resistant P. aeruginosa (resistant to ceftazidime and at least three of the agents listed above) recovered from various clinical samples from three patients in an intensive care burn unit from April 1997 to May 1997 and seven preserved isolates recovered from six patients in other medical wards at National Taiwan University Hospital from April 1996 to May 1997 were studied for their epidemiological relatedness. The epidemic could be attributed to a multidrug-resistant P. aeruginosa clone belonging to serogroup O:F (serogroup O:4) by means of antimicrobial susceptibility testing, O serogrouping, and analysis of the randomly amplified polymorphic DNA patterns generated by arbitrarily primed PCR of the isolates. The epidemic strain persisted in the three patients for weeks to months; in the meantime, these patients had received multiple antimicrobial agents for the management of intervening episodes of invasive infections (bacteremia, ventilator-associated pneumonia, and/or catheter-related sepsis) caused by this strain, as well as concomitant infections due to other organisms. The strain had been isolated only once previously, from a burn patient who was on the unit in December 1996. The present report, describing a small outbreak due to P. aeruginosa, documents the fact that a single clone of multidrug-resistant P. aeruginosa can cause long-term persistence in different body sites of burn patients and that the colonization can subsequently result in various severe infections.