METHODOLOGY: A follow-up in prospective cohort surveillance was conducted on patients admitted to an adult medical-surgical ICU of a university hospital and two governmental hospitals in Malaysia from October 2003 to December 2006. VAP was detected using CDC criteria which included clinical manifestation and confirmed endotracheal secretion culture results.
RESULTS: In total, 215 patients (2,306 patient-days) were enrolled into the study. The incidence of ICU-acquired device-related NI was 29.3 % (n = 63). The device-related VAP infection rate was 27.0 % (n = 58), with a mechanical ventilator utilization rate of 88.7%. The death rate due to all ICU-acquired NI including sepsis was 6.5%. The most common causative pathogen was Klebsiella pneumoniae (n = 27). Multivariate analysis using Cox regression showed that the risk factors identified were aspiration pneumonia (HR = 4.09; 95% CI = 1.24, 13.51; P = 0.021), cancer (HR = 2.51; 95% CI = 1.27, 4.97; P = 0.008), leucocytosis (HR=3.43; 95% CI= 1.60, 7.37; P=0.002) and duration of mechanical ventilation (HR=1.04; 95% CI = 1.00, 1.08; P = 0.030). Age, gender and race were not identified as risk factors in the multivariable analysis performed.
CONCLUSION: The incidence of VAP was comparable to that found in the National Nosocomial Infection Surveillance (NNIS) System report of June 1998. The incidence of VAP was considered high for the three hospitals studied.
RECENT FINDINGS: Optimal antibiotic treatment is challenging in critically ill patients with nosocomial pneumonia; most dosing guidelines do not consider the altered physiology and illness severity associated with severe lung infections. Antibiotic dosing can be guided by plasma drug concentrations, which do not reflect the concentrations at the site of infection. The application of aggressive dosing regimens, in accordance to the antibiotic's pharmacokinetic/pharmacodynamic characteristics, may be required to ensure rapid and effective drug exposure in infected lung tissues.
SUMMARY: Conventional antibiotic dosing increases the likelihood of therapeutic failure in critically ill patients with nosocomial pneumonia. Alternative dosing strategies, which exploit the pharmacokinetic/pharmacodynamic properties of an antibiotic, should be strongly considered to ensure optimal antibiotic exposure and better therapeutic outcomes in these patients.
MATERIALS AND METHODS: Three hundred and four isolates of E. coli and Klebsiella sp. had been selected via convenient sampling. These isolates were identified using conventional laboratory methods and their antimicrobial susceptibilities were determined using disc diffusion method. Those isolates were then proceeded with ESBL confirmatory test, cloxacillin-containing Muller Hinton confirmatory test, modified double disk synergy test and AmpC disk test.
RESULTS: Out of 304 isolates, 159 isolates were E. coli and 145 were Klebsiella sp. The prevalence of organisms which co-produced AmpC β-lactamase and ESBL enzymes were 3.0%. Besides that, 39 cefoxitin resistant and three cefoxitin susceptible isolates (13.8%) were proven to produce AmpC β-lactamase through AmpC disk test. Through the CLSI confirmatory test, 252 (82.9%) isolates were identified as ESBLs producers and the prevalence increased slightly when cloxacillin-containing Muller Hinton were used. Only three ESBLs positive organisms were positive for modified double disk synergy test.
CONCLUSION: Distinguishing between AmpC β-lactamase and ESBL-producing organisms has epidemiological significance as well as therapeutic importance. Moreover, AmpC β-lactamase and ESBLs co-producing organisms can lead to false negative ESBL confirmatory test. Therefore, knowing the local prevalence can guide the clinician in navigating the treatment.