Abstract: Inadequate empirical antibiotic therapy for serious Pseudomonas aeruginosa infections has been linked to increased mortality. We performed a retrospective cohort study of consecutive patients with ventilator-associated pneumonia, bacteraemia or other sterile-site infections caused by P. aeruginosa occurring during Intensive Care Unit admissions. One hundred and fifty-eight episodes of serious infection with P. aeruginosa occurred in 140 patients. Empirical antibiotic therapy was microbiologically adequate in 67% of episodes of infection. Patients with P. aeruginosa isolates resistant to piperacillin/tazobactam or cefepime were more likely to have received these antibiotics in the month prior to the P. aeruginosa infection or to have had a Gram-negative bacillus resistant to these antibiotics isolated in the month prior to the P. aeruginosa infection. From these data, we have developed simple algorithms for empirical antibiotic choice in seriously ill patients with suspected P. aeruginosa infections based on prior antibiotic exposure and prior isolation of antibiotic-resistant organisms. Application of these algorithms would have improved the adequacy of empirical antibiotic therapy from 67% to 80-84%. Routine empirical addition of amikacin to the beta-lactam would have increased the adequacy of the antibiotics to 96%. We conclude that knowledge of the prior receipt of beta-lactam antibiotics with activity against P. aeruginosa and the isolation of Gram-negative bacilli resistant to such antibiotics in the recent past can readily increase the adequacy of empirical antibiotic therapy for suspected P. aeruginosa infections.
Abstract: Clostridium tertium has been increasingly reported as a human pathogen. This organism is an aerotolerant Gram-positive rod that is often mistaken for other organisms, such as Lactobacillus or Bacillus species. We describe a case of a patient with a history of intravenous drug use presenting to UCLA-Olive View Medical Center with gas gangrene of both upper extremities. The organism was initially misidentified as a Lactobacillus species on aerobic culture plates. However, terminal spore formation was detected in this isolate on a sub-cultured anaerobic culture plate and this isolate was confirmed as C. tertium biochemically and genetically by 16S rDNA sequencing. Additional DNA cloning libraries made from the formalin-fixed specimen revealed Peptoniphilus species and an uncultured Clostridium clone, but not C. tertium. C. tertium might be a causative organism of gas-producing myonecrosis but such an association has never been described. Clinicians should be aware of the phenomenon of aerotolerance of some anaerobes and need to clarify the identification of organisms if the clinical picture does not fit the isolated organism.
Abstract: The diagnosis of ventilator-associated pneumonia has been clouded by uncertainty, because a reference standard has never been established. The use of invasive procedures to obtain respiratory tract samples for culture, with quantitation of the bacteria isolated, has been the approach most commonly advocated. Quantitation of bacteria from lower respiratory tract specimens can be used to distinguish colonization from infection. We review the invasive procedures (bronchoalveolar lavage, protected specimen brushing, nonbronchoscopic bronchoalveolar lavage, and blinded bronchial sampling), the methods of quantitation used, the types of catheters used, the sample collection methods, and the criteria used as cutoffs for the quantitative cultures. Quantitation of lower respiratory tract samples is inherently unstable from a mathematical perspective, given the variability in the volume of fluid instilled and reaspirated and the magnitude and complexity of the area being sampled. We also briefly review the use of quantitation for bacterial infections other than pneumonia, including urinary tract infection and catheter-related bacteremia. The variability in both the methods and reference criteria in the studies reviewed show that the quantitation approach is neither standardized nor evidence based.
Abstract: The ideal diagnostic approach for ventilator-associated pneumonia currently is based on invasive procedures to obtain respiratory tract cultures. Given the lack of consensus and relatively poor acceptance of full bronchoscopic bronchoalveolar lavage (BAL) and protected specimen brush (PSB), less invasive procedures have been developed. We review the nonbronchoscopic procedures (nonbronchoscopic bronchoalveolar lavage, including mini-BAL, blinded protected specimen, and blinded bronchial sampling) and endotracheal aspiration. We provide a critique of the methods used, the types of catheters inserted, and the sample collection methods. Most studies were flawed in that antibiotic use before initiation of the procedure was not controlled. The variability of both the methods and the criteria for the gold standard in the numerous investigations show that these procedures are neither standardized nor proven to be accurate and often did not improve management. Pending future studies, use of endotracheal aspirates without the use of quantitation seems to be a reasonable approach for clinicians who are not committed to an invasive procedure.
Abstract: A total of 108 cases of candidemia detected in 3 tertiary care university hospitals in Hawaii between January 2001 and December 2002 were retrospectively reviewed. Candida albicans, Candida glabrata, and Candida tropicalis accounted for 28% of the cases. Mortality among Filipino patients was significantly higher than that among other ethnic groups (71% vs 48%; P<.05).
Abstract: The common causes of ventilator-associated pneumonia (Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter cloacae, Acinetobacter spp) are frequently resistant to multiple antibiotic classes. S aureus develops resistance to all beta-lactam antibiotics by producing a modified penicillin-binding protein. Linezolid resistance arises by way of mutations in the 23S ribosomal subunit. Antibiotic resistance in gram-negative bacilli usually arises by way of beta-lactamase production, upregulation of efflux pumps, or loss of outer membrane proteins. The ability of bacteria to develop and disseminate new mechanisms of antibiotic resistance may outstrip the availability of new antibiotic classes.
Abstract: We report a case of E. coli meningitis presented initially without nuchal rigidity. Despite intensive care treatment, CSF was not sterilized and the patient died at 17 days after his admission. Patients with an unexplained altered sensorium with fever should undergo LP to evaluate for this rare entity and to direct early antimicrobial treatment which possesses efficacy for meningeal infection.
Abstract: PATHOPHYSIOLOGY: Critical care in obstetrics has many similarities in pathophysiology to the care of nonpregnant women. However, changes in the physiology of pregnant woman necessary to maintain homeostasis for both mother and fetus, especially during critical illness, result in complex pathophysiology. Understanding the normal physiologic changes during pregnancy, intrapartum, and postpartum is the key to managing critically ill obstetric patients with underlying medical diseases and pregnancy-related complications. HEMODYNAMIC MONITORING: When the pathophysiology of critically ill obstetric patients cannot be explained by noninvasive hemodynamic monitoring and the patient fails to respond to conservative medical management, invasive hemodynamic monitoring may be helpful in guiding management. Most important, the proper interpretation of hemodynamic data is predicated on knowledge of normal values during pregnancy and immediately postpartum. Invasive hemodynamic monitoring with pulmonary artery catherization has been used in the obstetric population, particularly in patients with severe preeclampsia associated with pulmonary edema and renal failure.
Abstract: Leptospirosis is a global zoonotic disease with a variety of clinical manifestations. We report an outbreak of leptospirosis in the Yaeyama Islands, Japan, in the summer of 1999 associated with heavy rainfall. Fourteen people were diagnosed with leptospirosis and required hospitalization. All cases were found to have exposure to contaminated soil or water. A history of recreational activities involving water sports was more frequent (71%) than occupational risk factors related to agriculture or construction (29%). Fever was the primary symptom in all cases, followed by chills (93%), headache (86%), myalgias (57%) and conjunctival suffusion (57%). All cases were successfully treated with antimicrobial therapy except one patient who improved spontaneously. Jarisch-Herxheimer reactions were seen in six cases (43%). The increasing incidence of leptospirosis related to recreational sports is an important public health problem in resort areas. A high-index of suspicion, early treatment, and prevention are crucial in this latently endemic area.
Abstract: Intensive care units (ICUs) frequently are the epicenter of nosocomial infections with antibiotic-resistant bacteria. Optimization of antibiotic therapy for seriously ill patients with bacterial infections appears to have a strong influence on outcome. Laboratories can aid in provision of appropriate antibiotic therapy by providing clinicians with "antibiograms" to aid empiric antibiotic choice and by providing minimal inhibitory concentrations of key antibiotics so that antibiotic dosing is optimized to key pharmacodynamic targets. Laboratories also play a crucial role in the prevention of antibiotic resistance in the ICU. Molecular epidemiologic evidence of an oligoclonal outbreak of infections orients prevention measures toward investigation of common environmental sources of infection and prevention of patient-to-patient transmission. In contrast, evidence of polyclonality shifts prevention of antibiotic resistance to antibiotic management strategies.
