Pseudomonas Aeruginosa Bacteremia Research Articles

Beta-Lactam vs. Fluoroquinolone Monotherapy for Pseudomonas aeruginosa Infection: A Systematic Review and Meta-Analysis.

Introduction: Pseudomonas aeruginosa (PA) is a leading cause of healthcare-associated infections. A variety of antibiotic classes are used in the treatment of PA infections, including beta-lactams (BLs) and fluoroquinolones (FQs), given either together in combination therapy or alone in monotherapy. A systematic review and meta-analysis were performed to evaluate the therapeutic efficacy of BL agents versus FQ agents as active, definitive monotherapy in PA infections in adults. Methods: Comprehensive literature searches of the Medline and Scopus electronic databases, alongside hand searches of the Cochrane Database of Systematic Reviews, PubMed, and Google Scholar, were performed without a time restriction to identify studies published in English comparing BL and FQ agents given as monotherapy for PA infection in hospitalized adults for which mortality, bacteriological eradication, or clinical response was evaluated. One reviewer screened search results based on pre-defined selection criteria. Two reviewers independently assessed included studies for methodological quality using NIH assessment tools. Two fixed-effects meta-analyses were performed. Results: A total of 368 articles were screened, and six studies involving 338 total patients were included in the meta-analysis. Upon evaluation of methodological quality, two studies were rated good, three fair, and one poor. A meta-analysis of three studies demonstrates FQ monotherapy is associated with significantly improved survival compared to BL monotherapy for patients with PA bacteremia (OR, 3.65; 95% CI, 1.27–10.44; p = 0.02). A meta-analysis of three studies demonstrates FQ monotherapy is associated with equivalent bacteriological eradication compared to BL monotherapy for PA pneumonia or skin and soft tissue infection (RD, 0.07; 95% CI, −0.09 to 0.24; p = 0.39). Conclusion: The meta-analyses demonstrate FQ monotherapy significantly improves survival in PA bacteremia and is associated with similar rates of bacteriological eradication in pneumonia and skin and soft tissue infection caused by PA compared to BL monotherapy. However, more research is needed to make meaningful clinical recommendations.

Clinical characteristics, appropriateness of empiric antibiotic therapy, and outcome of Pseudomonas aeruginosa bacteremia across multiple community hospitals.

There is relatively little contemporary information regarding clinical characteristics of patients with Pseudomonas aeruginosa bacteremia (PAB) in the community hospital setting. This was a retrospective, observational cohort study examining the clinical characteristics of patients with PAB across several community hospitals in the USA with a focus on the appropriateness of initial empirical therapy and impact on patient outcomes. Cases of PAB occurring between 2016 and 2019 were pulled from 8 community medical centers. Patients were classified as having either positive or negative outcome at hospital discharge. Several variables including receipt of active empiric therapy (AET) and the time to receiving AET were collected. Variables with a p value of < 0.05 in univariate analyses were included in a multivariable logistic regression model. Two hundred and eleven episodes of PAB were included in the analysis. AET was given to 81.5% of patients and there was no difference in regard to outcome (p = 0.62). There was no difference in the median time to AET in patients with a positive or negative outcome (p = 0.53). After controlling for other variables, age, Pitt bacteremia score ≥ 4, and septic shock were independently associated with a negative outcome. A high proportion of patients received timely, active antimicrobial therapy for PAB and time to AET did not have a significant impact on patient outcome.

Recurrent Pseudomonas aeruginosa Bacteremia

Introduction As part of an institutional review board–approved quality improvement project reviewing 10 years of experience (2009–2018) with Pseudomonas aeruginosa bacteremia (PAB) at our institution, we identified 15 patients with recurrent Pseudomonas bacteremia. Because recurrent P. aeruginosa bacteremia (RPAB) is uncommon, we reviewed our patients with PAB to evaluate its occurrence, epidemiology, clinical characteristics, and outcomes of care. Methods This was an institutional review board–approved quality improvement project. We reviewed the medical records of all patients with PAB from January 1, 2009, to December 31, 2018, and identified the subset of patients with RPAB. We report the incidence, epidemiology, source of bacteremia, comorbid conditions, treatment, and outcome for patients with RPAB. We compare these data to previously published series of PAB patients with RPAB. Results We identified 268 episodes of PAB. One patient with 6 occurrences of PAB secondary to injection drug use–associated tricuspid valve endocarditis was excluded because of noncompliance with therapy. This left 262 episodes of PAB for evaluation. Fifteen patients had a total of 19 episodes of RPAB: 13 patients had 2 episodes (1 recurrence each), 1 patient had 3 episodes (2 recurrences), and 1 patient had 5 episodes (4 recurrences). The recurrence rate was 7.3% (19/262). The mean and median ages for patients with RPAB were 59 and 58 years, respectively. The time between episodes of PAB ranged from 26 to 688 days with a mean and median of 166 and 97 days, respectively. There were 3 patients (16%) with different sources of bacteremia for consecutive episodes of PAB: 1 with neutropenic sepsis followed by acute mastoiditis, 1 with cellulitis of the leg followed by an infected sacral pressure ulcer, and 1 with pneumonia and then an infected arteriovenous graft. The source of the recurrent episode was the same as the prior episode in 16 instances (84%): (1) skin and soft tissue infection (7 episodes), (2) central venous catheter infection (3 episodes), (3) genitourinary infection (2 episodes), (4) pneumonia (1 episode), (5) infected aortic vascular graft (1 episode), (6) obstructive cholangitis (1 episode), and (7) primary bacteremia (1 episode). All but 2 patients had multiple comorbid conditions, and all but 1 patient with RPAB had ≥1 of 5 risk factors for PAB as reported in the literature. Six (32%) of 19 episodes of RPAB resulted in death. Five of 6 patients with fatal RPAB received appropriate antimicrobial therapy at the initial presentation to the hospital for the second/fatal episode. Infectious disease consultation was obtained in all but 1 episode of RPAB. Conclusions Recurrent PAB accounted for 19 (7.3%) of 262 episodes of PAB in our 10-year study. It was associated with multiple comorbid conditions. The recurrent episode was usually from the same source as the prior episode of PAB. Sources of RPAB were diverse (as discussed previously), and mortality was 32% despite appropriate antipseudomonal antimicrobial therapy in all but 1 episode of those who died. We review the literature for patients with RPAB and compare these patients with those in our patient population.

The relationship between clinical outcomes and empirical antibiotic therapy in patients with community-onset Gram-negative bloodstream infections: a cohort study from a large teaching hospital.

Antibiotic-resistant Gram-negative bacteraemias (GNB) are increasing in incidence. We aimed to investigate the impact of empirical antibiotic therapy on clinical outcomes by carrying out an observational 6-year cohort study of patients at a teaching hospital with community-onset Escherichia coli bacteraemia (ECB), Klebsiella pneumoniae bacteraemia (KPB) and Pseudomonas aeruginosa bacteraemia (PsAB). Antibiotic therapy was considered concordant if the organism was sensitive in vitro and discordant if resistant. We estimated the association between concordant vs. discordant empirical antibiotic therapy on odds of in-hospital death and ICU admission for KPB and ECB. Of 1380 patients, 1103 (79.9%) had ECB, 189 (13.7%) KPB and 88 (6.4%) PsAB. Discordant therapy was not associated with increased odds of either outcome. For ECB, severe illness and non-urinary source were associated with increased odds of both outcomes (OR of in-hospital death for non-urinary source 3.21, 95% CI 1.73-5.97). For KPB, discordant therapy was associated with in-hospital death on univariable but not multivariable analysis. Illness severity was associated with increased odds of both outcomes. These findings suggest broadening of therapy for low-risk patients with community-onset GNB is not warranted. Future research should focus on the relationship between patient outcomes, clinical factors, infection focus and causative organism and resistance profile.

Bacteraemia due to extensively drug-resistant Pseudomonas aeruginosa sequence type 235 high-risk clone: Facing the perfect storm

Predictors of mortality and the impact of multidrug resistance and virulence on patients with Pseudomonas aeruginosa (PA) bacteraemia were evaluated. Patients with PA bacteraemia in a 12-month period were retrospectively analysed. Carbapenemase production, molecular typing and identification of virulence factor ExoU were carried out. The activity of ceftolozane-tazobactam and ceftazidime-avibactam was also investigated. The primary endpoint was 30-day crude mortality. Of 64 patients with bacteraemia, 24 (37.5%) were caused by extensively drug-resistant PA (XDR-PA): 10 (41.7%) cases involved the VIM-2 carbapenemase-producing ST175 clone, 11 (45.8%) the GES-5 carbapenemase-producing ST235 clone, and 3 (12.5%) were non-carbapenemase producers. The exoU genotype was detected in all ST235 strains and in 6 (15%) of the non-XDR isolates. Ceftazidime-avibactam (58.3%) showed greater activity than ceftolozane-tazobactam (12.5%) against XDR-PA isolates, particularly in GES-5 producers (100%). The 30-day crude mortality rate in patients with XDR-PA bacteraemia was higher than in cases caused by susceptible strains (62.5% vs. 30%; P=0.02). Multivariate analysis showed that independent risk factors associated with 30-day crude mortality were Pitt score ≥2 (OR, 42.31; 95% CI, 4.88-366.7; P=0.001) and respiratory source of bacteraemia (OR, 49.13; 95% CI 3.89-620.5; P=0.003). Stratified analysis adjusting for respiratory source revealed a non-significant trend towards higher mortality in patients with bacteraemia caused by the ST235 clone and exoU-producing isolates. These data support the notion that the XDR phenotype associated with the GES-5 carbapenemase-producing ST235 clone and the exoU-positive genotype adversely affects the outcome of patients with PA bacteraemia, particularly those with respiratory tract infections and a severe clinical presentation.

Successful Treatment of Multi-Drug Resistant Pseudomonas aeruginosa Bacteremia with the Recommended Renally Adjusted Ceftolozane/Tazobactam Regimen.

IntroductionCeftolozane/tazobactam (C/T) is a novel antibiotic approved for complicated intra-abdominal and urinary tract infections caused by Gram-positive and Gram-negative organisms, including some MDR strains. Little is known about the use of this agent for treatment of bacteremia and even less so about the appropriateness of the renally defined regimens. We describe a case of a 66-year-old man with a history of chronic kidney disease (baseline Cr = 3–4 mg/dl) and recurrent nephrolithiasis with bilateral stents who had positive concurrent urine and blood cultures for MDR Pseudomonas aeruginosa (PSA), susceptible only to amikacin and colistin. Due to the MDR phenotype and his underlying kidney disease, the 375 mg (250 mg/125 mg) dose of C/T was given as monotherapy every 8 h for his bloodstream infection.MethodsOnce steady state was anticipated, blood was obtained at the end of infusion (1 h), and at 3, 5 and 8 h for drug concentration determination using a validated high-performance liquid chromatography method at the Center for Anti-Infective Research and Development, Hartford Hospital, Hartford.ResultsThe minimum inhibitory concentration (MIC) for the PSA was 2/4 for C/T, indicating susceptibility. Concentration of ceftolozane of 21.87 µg/ml at 8 h indicated that serum concentrations were maintained above the MIC throughout the dosing interval. The patient was given 25 days of C/T and experienced a successful clinical outcome. Blood cultures obtained at 1 and 3 weeks after completion of treatment remained sterile. No adverse events were attributed to C/T.ConclusionIn this patient, the renally adjusted dose of C/T was safe and provided sufficiently high drug concentrations that exceeded the MIC of the infecting organism over the course of therapy. More data are required to determine the clinical utility of C/T in the setting of MDR PSA bacteremia.

Risk factors associated with unfavorable short-term treatment outcome in patients with documented Pseudomonas aeruginosa infection.

Invasive infections with Pseudomonas aeruginosa (PA) are associated with significant morbidity and mortality. While risk factors for mortality have been identified, their influence on short-term outcomes impacting treatment selection has not been reported. The objective of this study was to evaluate the relationship between select patient- and treatment-related factors and short-term outcomes in patients with PA pneumonia and/or bacteremia. Large academic medical center in the United States. This IRB-approved single-center, retrospective case-cohort study included patients >18 years of age with culture-confirmed PA bacteremia and/or pneumonia receiving antimicrobial agent(s) active against PA. Risk of unfavorable short-term treatment result. The population consisted of 117 patients (40 [34 %] and 77 [66 %] in the unfavorable and not-unfavorable groups, respectively). Baseline characteristics including age (mean of 63 years), gender (55 % male), Charlson score, creatinine clearance, and body mass index were comparable between groups. Piperacillin/tazobactam was the most common monotherapy antibiotic (46 and 33 % in unfavorable and not-unfavorable groups, respectively). Combination therapy primarily consisted of a beta-lactam plus ciprofloxacin in both unfavorable (10 %) and not-unfavorable (20 %) outcome groups. The preliminary regression model indicated that SIRS, direct ICU admission, and vasopressor therapy were associated with an unfavorable outcome. In addition, patients who received more than two active antimicrobials had a reduced risk of an unfavorable outcome. The final regression model revealed that vasopressor therapy (odds ratio [OR] 6.0; 95 % confidence interval [95 % CI] 2.3, 17) was associated with an unfavorable outcome, while receipt of greater than two active antibiotics was associated with a reduced risk of an unfavorable outcome (OR 0.26; 95 % CI 0.07, 0.83). Treatment with more than two agents with activity against PA was associated with a reduced risk of an unfavorable short-term treatment outcome in patients with bacteremia and/or pneumonia.

Antibiotic Therapy and Clinical Outcomes of Pseudomonas Aeruginosa (PA) Bacteraemia

Pseudomonas aeruginosa (PA) bacteraemia is associated with high morbidity and mortality. We assessed clinical outcomes in patients with PA bacteraemia treated with piperacillin-tazobactam (TZP) versus other antibiotics, and monotherapy versus combination, all with proven activity by disc testing without minimum inhibitory concentration (MIC) data. All patients with PA bacteraemia in 2007 to 2008 were reviewed for demographic, comorbidity, clinical, laboratory, treatment and outcome data. Primary outcome was 30-day mortality. Secondary outcomes included microbiological clearance, clinical response and length of stay (LOS). Median age for 91 patients was 65 years. Median Simplified Acute Physiology Score (SAPS) II score was 30. Monotherapy was used in 77 cases: 42 on ceftazidime, 17 on TZP, 10 on carbapenems, and 8 on other antipseudomonal antibiotics. The 30-day mortality was 20.9%, and similar between ceftazidime and TZP versus other antibiotics respectively. More patients in combination versus monotherapy group had cardiovascular diseases, diabetes mellitus and vascular access as source of bacteraemia. Patients on monotherapy had higher 30-day mortality (24.7% vs 0%, P = 0.037). Multivariate analysis identified SAPS II score (OR = 1.097, 95% CI, 1.032 to 1.166, P = 0.003) and cancer (OR = 4.873, 95% CI, 1.235 to 19.223, P = 0.024) as independent predictors of 30-day mortality. TZP appeared to be an effective culture-guided antibiotic for PA bacteraemia. High 30-day mortality in monotherapy might be confounded by comorbidity, illness severity and sample size. Cancer patients and a high SAPS II score were independent predictors of 30-day mortality.

Pseudomonas Aeruginosa Bacteremia in Patients Supported with a Left Ventricular Assist Device Is Associated with an Increased Risk of Hemorrhagic Stroke

Pseudomonas Aeruginosa Bacteremia in Patients Supported with a Left Ventricular Assist Device Is Associated with an Increased Risk of Hemorrhagic Stroke

Pseudomonas aeruginosa Ventilator-associated Pneumonia. Predictive Factors of Treatment Failure

The predictive factors of treatment failure for ventilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa (PA) remain uncertain. To describe PA-VAP recurrence prognosis and to identify associated risk factors in a large cohort of intensive care unit patients with PA-VAP. From the multicenter OUTCOMEREA database (1997-2011), PA-VAP onset and recurrence were recorded. All suspected cases of VAP were confirmed by a positive quantitative culture of a respiratory sample. Multidrug-resistant PA strains were defined by the resistance to two antibiotics among piperacillin, ceftazidime, imipenem, colistine, and fluoroquinolones (FQ). An extensively resistant PA was defined by resistance to piperacillin, ceftazidime, imipenem, and FQ. A treatment failure was defined as a PA-VAP recurrence or by the death occurrence. A total of 314 patients presented 393 PA-VAP. Failure occurred for 112 of them, including 79 recurrences. Susceptible, multidrug resistant, and extensively resistant PA represented 53.7%, 32%, and 14.3% of the samples, respectively. Factors associated with treatment failure were age (P = 0.02); presence of at least one chronic illness (P = 0.02); limitation of life support (P = 0.0004); a high Sepsis-Related Organ Failure Assessment score (P < 0.0001); PA bacteremia (P = 0.003); and previous use of FQ before the first PA-VAP (P = 0.0007). The failure risk was not influenced by the strain resistance profile or by the biantibiotic treatment, but decreased in case of VAP treatment that includes FQ (subdistribution hazard ratio, 0.5 [0.3-0.7]; P = 0.0006). However, the strain resistance profile slowed down the intensive care unit discharge hazard (subdistribution hazard ratio, 0.6 [0.4-1.0]; P = 0.048). Neither resistance profile nor biantibiotic therapy decreased the risk of PA-VAP treatment failure. However, the profile of PA resistance prolonged the length of stay. Better evaluation of the potential benefit of an initial treatment containing FQ requires further randomized trials.

Effect of Adequate Single-Drug vs Combination Antimicrobial Therapy on Mortality in Pseudomonas aeruginosa Bloodstream Infections: A Post Hoc Analysis of a Prospective Cohort

Empirical combination therapy is recommended for patients with known or suspected Pseudomonas aeruginosa (PA) infection as a means to decrease the likelihood of administering inadequate antimicrobial treatment, to prevent the emergence of resistance, and to achieve a possible additive or even synergistic effect. We performed a post hoc analysis of patients with PA bloodstream infections from a published prospective cohort. Mortality was compared in patients treated with adequate empirical and definitive combination therapy (AECT, ADCT), and adequate empirical and definitive single-drug therapy (AESD, ADSD). Confounding was controlled by Cox regression analysis, and a propensity score for receiving AECT or ADCT was also used. The final cohort comprised 593 patients with a single episode of PA bacteremia. The 30-day mortality was 30% (176 patients); 76 patients (13%) died during the first 48 hours. The unadjusted probabilities of survival until day 30 were 69.4% (95% confidence interval [CI], 59.1-81.6) for the patients receiving AECT, 73.5% (95% CI, 68.4%-79.0%) for the AESD group, and 66.7% (95% CI, 61.2%-72.7%) for patients who received inadequate empirical therapy (P = .17, log-rank test). After adjustment for confounders, the AESD group (adjusted hazard ratio [AHR], 1.17; 95% CI, .70-1.96; P = .54) and patients who received ADSD (AHR, 1.34; 95% CI, .73-2.47; P = .35) showed no association with 30-day mortality compared with the AECT and ADCT groups, respectively. These results suggests that treatment with combination antimicrobial therapy did not reduce the mortality risk compared with single-drug therapy in PA bloodstream infections.

Epidemiology of bacteremia caused by uncommon non-fermentative gram-negative bacteria

BackgroundPrevalence of bacteremia caused by non-fermentative gram-negative bacteria (NFGNB) has been increasing over the past decade. Although many studies have already investigated epidemiology of NFGNB bacteremia, most focused only on common NFGNB including Pseudomonas aeruginosa (PA) and Acinetobacter baumannii (AB). Knowledge of uncommon NFGNB bacteremia is very limited. Our study aimed to investigate epidemiology and identify factors associated with uncommon NFGNB bacteremia.MethodsThis observational study was conducted at a university hospital in Thailand during July 1, 2007-Dec 31, 2008. All patients who had at least one blood culture positive for NFGNB and met the criteria for systemic inflammatory response syndrome within 24 hours before/after obtaining the blood culture were enrolled. The NFGNB isolates that could not be satisfactorily identified by the standard biochemical assays were further characterized by molecular sequencing methods. To identify factors associated with uncommon NFGNB bacteremia, characteristics of patients in the uncommon NFGNB group were subsequently compared to patients in the common NFGNB group (AB and PA bacteremia).ResultsOur study detected 223 clinical isolates of NFGNB in 221 unique patients. The major causative pathogens were AB (32.7%), followed by PA (27.8%), Stenotrophomonas maltophilia (5.4%), Acinetobacter lwoffii (4.9%) and Burkholderia pseudomallei (2.7%). Infection-related mortality was 63.0% in the AB group, 40.3% in the PA group and 17.4% in the uncommon NFGNB group. Factors associated with uncommon NFGNB bacteremia (OR [95% CI]; p-value) were male sex (0.28 [0.14-0.53]; p < 0.001), hospital-acquired infection (0.23 [0.11-0.51]; p < 0.001), recent aminoglycosides exposure 0.23 [0.06-0.8]; p = 0.01), primary bacteremia (6.43 [2.89-14.2]; p < 0.001]), catheter related infection (4.48 [1.54-13.06]; p < 0.001) and recent vancomycin exposure (3.88 [1.35-11.1]; p = 0.02).ConclusionsOur distribution of causative pathogens was slightly different from other studies. The common NFGNB group had a remarkably higher ID-mortality than the uncommon NFGNB group. Knowledge of factors associated with uncommon NFGNB bacteremia would help physicians to distinguish between low vs. high risk patients.

The impact of early adequate antimicrobial therapy on 14-day mortality in patients with monomicrobial Pseudomonas aeruginosa and Acinetobacter baumannii bacteremia

The impact of colistin therapy for early adequate antimicrobial therapy on clinical outcomes has rarely been evaluated in patients with Pseudomonas aeruginosa bacteremia (PAB) or Acinetobacter baumannii bacteremia (ABB). We investigated the impact of early adequate antimicrobial therapy on 14-day mortality in 149 patients with monomicrobial PAB and ABB at two medical centers where colistin treatment was frequently used. Patients who survived the first 14 days of PAB/ABB received adequate antimicrobial therapy within 3 days of bacteremia more frequently than those who died (53.3 vs. 38.6%), although this finding is not statistically significant (p = 0.10). After excluding patients who received adequate colistin therapy, the difference was statistically significant (94.6 vs. 58.8%, p = 0.001). In a multiple regression model excluding patients who received colistin therapy, adequate antimicrobial therapy within 3 days of bacteremia was a preventive factor for 14-day mortality (adjusted OR = 0.23, 95% CI = 0.07-0.80, p = 0.02). In another multiple regression model including patients who received colistin, compared to inadequate antimicrobial therapy, adequate non-colistin therapy was a preventive factor for 14-day mortality (aOR = 0.22, 95% CI = 0.07-0.78, p = 0.019), but adequate colistin therapy was not (aOR = 8.20, 95% CI = 1.07-62.90, p = 0.043). The favorable impact of early adequate antimicrobial therapy on 14-day mortality in patients with monomicrobial PAB/ABB may be lessened in the clinical practice of using colistin frequently. Further studies may be needed to evaluate the clinical impact of colistin therapy in patients with PAB or ABB.

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Introduction: Pseudomonas aeruginosa (PA) represents an important cause of bacteremia in critically ill patients and can result in substantial mortality. Initially appropriate antibiotic therapy (IAAT) is a key determinant of outcome in bacteremia. One component of IAAT reflects the in vitro activity of the antibiotic against the culprit pathogen. Administration of an agent to which the organism is not susceptible(NonSus) per se defines inappropriate therapy. Recently, the break points defining NonSus have changed for PA relative to piperacillin/tazobactam(PT). It is unclear how this alteration will change potential rates of IAAT for PA bacteremia. Hypothesis: We hypothesized that the new rubric defining NonSus for PA to PT would significantly decrease the rate of IAAT with empiric PT use. Methods: We retrospectively identified all cases of PA bacteremia at our institution between Jan 2010 and May 2012. We only included first episodes of bacteremia and excluded all duplicate isolates. The minimum inhibitory concentration 90 (MIC90) of the PA to PT was determined via disk diffusion by trained lab personnel. MIC90s were defined as NonSus based on both the older and now more recent recommendations of the Clinical Laboratory Standard Institute (CLSI). Under the older system, organisms with an MIC90 of >64/4 mg/dl were deemed NonSus while with the newer rubric isolates with an MIC90 of >16/4 mg/dl are categorized as NonSus. Rates of NonSus served as our primary endpoint. We conducted a subgroup analysis in those isolates that were recovered from critically ill patients. Results: The cohort included 98 cases of bacteremia. The median MIC90 to PT was 8/4 mg/dl. Under the older CLSI scheme, 13.3% of isolates were NonSus to PT compared to 20.4% with the new criteria. This approximate 7% absolute increase in rates of NonSus and thus potentially inappropriate therapy was not significant(p=0.252). Among critically ill subjects(n=49) rates of NonSus would increase from 16.3% to 19.7% (p=0.805). Conclusions: The newer CLSI approach to defining the breakpoints for PA to PT does not alter the proportion of patients classified as having NonSus isolates, irrespective of patient severity of illness. This suggests that rates of IAAT with empiric PT for PA bacteremia are unlikely to be altered purely because of the recent changes proposed by CLSI.

C2 Deficiency Presenting as Pseudomonas Aeruginosa Bacteremia

C2 deficiency (C2D) is the most common homozygous complement deficiency, leading to susceptibility to infection with encapsulated bacteria due to defective opsonization. Pseudomonas aeruginosa is not a typical encapsulated bacterium, although reports have indicated that it can activate the complement system. Here we present an infant with Pseudomonas aeruginosa bacteremia who subsequently was diagnosed with C2D. Immunoglobulins, CH50, C2 level and function and C4 level were performed by the National Jewish Health Complement Laboratory and ARUP Laboratories. A 10-month-old Hispanic male with no significant past medical history presented to the hospital with a 2 day history of vomiting, diarrhea and fever to 102oF. Because of his progressive illness, he was admitted to the hospital for infectious workup. His blood culture grew Pseudomonas aeruginosa after 24hrs while urine and CSF cultures were negative. He was treated with ceftazidime without any complications. An immunodeficiency evaluation revealed normal immunoglobulin levels and normal sweat chloride test. His CH50 = 0 (60-144), C4 = 12 mg/dL (16-47), C2 = 2.8 mcg/mL (22.2-39.8), and C2 function = 21084 Units/mL (15354-46242). C2 levels for his father and mother were 15.1 and 16.9, respectively. C2D can present with Pseudomonas aeruginosa bacteremia. One study has demonstrated that the serum of a patient with C2 defect showed weak bactericidal activity against Pseudomonas aeruginosa strains as compared to normal serum. This case illustrates the importance of C2 in protecting from non-encapsulated bacteria that can evade the complement system. Complement system should be evaluated in patients with Pseudomonas bacteremia.

Prevalence of Type III Secretion Protein Exoenzymes and Antimicrobial Susceptibility Patterns from Bloodstream Isolates of Patients with Pseudomonas aeruginosa Bacteremia

The purpose of this study was to determine the prevalence of two type III secretion effector proteins, exoU and exoS from bloodstream isolates of hospitalized patients with Pseudomonas aeruginosa (PSA) bacteremia, to characterize antimicrobial susceptibility patterns, and to compare mortality rates.PSA bloodstream isolates and antibiotic susceptibility profiles were collected from a university-affiliated hospital. exoS and exoU genes were detected by polymerase chain reaction. Hospital mortality was assessed by medical chart review.119 of 122 (97.5%) PSA bloodstream isolates contained either the exoS or exoU genes. exoS was the most prevalent (n=86; 70.5%) followed by exoU (n=31; 25.4%), both genes (n=2; 1.6%) or neither gene (n=3; 2.5%). Isolates containing the exoU gene were significantly more likely to be resistant to cefepime, ceftazidime, piperacillintazobactam, carbapenems, fluoroquinolones, and gentamicin (p<0.05 for all). Mortality was high in patients with PSA bacteremia and did not differ among patients infected with the exoS isolates (n=37; 43%) or exoU isolates (n=11; 35%).One of two type III secretion effector proteins were almost universally present in PSA bloodstream isolates. Isolates containing the exoU gene were more likely to be resistant to multiple antibiotics.

PSEUDOMONAS AERUGINOSA: EPIDEMIOLOGY OF BACTEREMIA AND ANTIMICROBIAL SUSCEPTIBILITY PATTERN IN A TEACHING HOSPITAL IN KUALA LUMPUR

A cross-sectional study of 109 patients with Pseudomonas aeruginosabacteremia from the University of Malaya Medical Centre (UMMC) in the years 2000 and 2001 was conducted to describe epidemiological features, underlying diseases, possible source of infection, early mortality among patients as well as the antibiotic susceptibility pattern of patients' isolates. Further analysis of the 87 patient records that were available revealed that the mean age was 48.5 years (SD ' 25.1). Fifty-two per cent of cases were male and 48% female. Seventy-nine per cent of infections were nosocomially acquired, 33% of bacteremias were polymicrobial, 47% of patients had a continuous bladder drainage catheter (CBD) in situ, 33% had a central venous catheter (CVL) present at the time of bacteremia and 30% were ventilated. Sixty-eight per cent of patients had an underlying immunosuppressed state and 26% had undergone surgery involving general anesthesia in the week prior to isolating P. aeruginosa. Among the 23 patients with early mortality, 61% were on inappropriate antimicrobials. Most of the patients' isolates were sensitive to imipenem (86%), ciprofloxacin (81%), ceftazidime (79%), gentamicin (78%) and cefoperazone (77%). Among the community acquired strains, however, there was 100% sensitivity to imipenem, ceftazidime, cefoperazone and ciprofloxacin.