Risk factors for carriage of antimicrobial-resistant bacteria in community dwelling-children in the Asia-Pacific region: a systematic review and meta-analysis

Background

Antimicrobial resistance is an increasingly important issue in public health as antibiotics are overused. Resistance to antimicrobial agents can pose significant challenges to infection treatment.

Objectives

To evaluate risk factors associated with carriage of antimicrobial-resistant (AMR) bacteria in children in the Asia-Pacific region to consolidate evidence for future implementation of antibiotic prescribing practice.

Methods

Three electronic databases-PubMed, EMBASE and Cochrane Library-were searched. Observational studies that investigated the risk factors for carriage of MRSA, penicillin-resistant Streptococcus pneumoniae, ESBL-producing Escherichia coli and Klebsiella pneumoniae among the paediatric population in community settings in the Asia-Pacific region were considered eligible. Summary statistics from the identified studies were pooled using meta-analyses.

Results

From the 4145 search results, 25 papers were included in this review. Sixteen papers were included in the meta-analysis based on reported risk factors. Young age of 2-6 months compared with children aged 7-60 months (OR 2.74, 95% CI: 1.75-4.29), antibiotic use within the past 3 months (OR 2.65, 95% CI: 1.70-4.12), daycare attendance (OR 1.49, 95% CI: 1.17-1.91) and hospital admission within the past 3 months (OR 3.43, 95% CI: 2.13-5.51) were found to be significant risk factors for AMR bacterial carriage, whilst breastfeeding (OR 0.69, 95% CI: 0.60-0.81) and concurrent colonization of S. pneumoniae (OR 0.59, 95% CI: 0.38-0.91) are protective factors.

Conclusions

The findings support that there are a number of significant risk factors associated with carriage of AMR bacteria in the Asia-Pacific paediatric population. To combat antimicrobial resistance in the future, these risk factors should be considered, and measures taken to mitigate associated carriage.

Surgical site infection with extended-spectrum β-lactamase-producing Enterobacteriaceae after cardiac surgery: incidence and risk factors

OBJECTIVE

To determine the incidence, microbiology and risk factors for sternal wound infection (SWI) with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) following cardiac surgery.

METHODS

We performed a retrospective analysis between January 2006 and December 2015 of prospective surveillance of a cohort of patients with cardiac surgery at a single centre (Paris, France). SWI was defined as the need for reoperation due to sternal infection. All patients with an initial surgery under extracorporeal circulation and diagnosed with an SWI caused by Enterobacteriaceae isolates were included. We compared patients infected with at least one ESBL-PE with those with SWI due to other Enterobacteriaceae by logistic regression analysis.

RESULTS

Of the 11 167 patients who underwent cardiac surgery, 412 (3.7%) developed SWI, among which Enterobacteriaceae were isolated in 150 patients (36.5%), including 29 ESBL-PE. The main Enterobacteriaceae (n = 171) were Escherichia coli in 49 patients (29%) and Enterobacter cloacae in 26 (15%). Risk factors for SWI with ESBL-PE in the multivariate logistic regression were previous intensive care unit admission during the preceding 6 months (adjusted odds ratio (aOR) 12.2; 95% CI 3.3-44.8), postoperative intensive care unit stay before surgery for SWI longer than 5 days (aOR 4.6; 95% CI 1.7-11.9) and being born outside France (aOR 3.2; 95% CI 1.2-8.3).

CONCLUSIONS

Our results suggest that SWI due to ESBL-PE was associated with preoperative and postoperative unstable state, requiring an intensive care unit stay longer than the usual 24 or 48 postoperative hours, whereas being born outside France may indicate ESBL-PE carriage before hospital admission.

Modeling Nosocomial Infections of Methicillin-Resistant Staphylococcus aureus with Environment Contamination<sup/>

In this work, we investigate the role of environmental contamination on the clinical epidemiology of antibiotic-resistant bacteria in hospitals. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in different parts of the body. It is tougher to treat than most strains of Staphylococcus aureus or staph, because it is resistant to some commonly used antibiotics. Both deterministic and stochastic models are constructed to describe the transmission characteristics of MRSA in hospital setting. The deterministic epidemic model includes five compartments: colonized and uncolonized patients, contaminated and uncontaminated health care workers (HCWs), and bacterial load in environment. The basic reproduction number R ₀ is calculated, and its numerical and sensitivity analysis has been performed to study the asymptotic behavior of the model, and to help identify factors responsible for observed patterns of infections. A stochastic epidemic model with stochastic simulations is also presented to supply a comprehensive analysis of its behavior. Data collected from Beijing Tongren Hospital will be used in the numerical simulations of our model. The results can be used to provide theoretical guidance for designing efficient control measures, such as increasing the hand hygiene compliance of HCWs and disinfection rate of environment, and decreasing the transmission rate between environment and patients and HCWs.

A prediction tool for nosocomial multi-drug Resistant Gram-Negative Bacilli infections in critically ill patients - prospective observational study

Background

The widespread use of empiric broad spectrum antibiotics has contributed to the global increase of Resistant Gram-Negative Bacilli (RGNB) infections in intensive care units (ICU). The aim of this study was to develop a tool to predict nosocomial RGNB infections among ICU patients for targeted therapy.

Methods

We conducted a prospective observational study from August'07 to December'11. All adult patients who were admitted and stayed for more than 24 hours at the medical and surgical ICU's were included. All patients who developed nosocomial RGNB infections 48 hours after ICU admission were identified. A prediction score was formulated by using independent risk factors obtained from logistic regression analysis. This was prospectively validated with a subsequent cohort of patients admitted to the ICUs during the following time period of January-September 2012.

Results

Seventy-six patients with nosocomial RGNB Infection (31bacteremia) were compared with 1398 patients with Systemic Inflammatory Response Syndrome (SIRS) without any gram negative bacterial infection/colonization admitted to the ICUs during the study period. The following independent risk factors were obtained by a multivariable logistic regression analysis - prior isolation of Gram negative organism (coeff: 1.1, 95% CI 0.5-1.7); Surgery during current admission (coeff: 0.69, 95% CI 0.2-1.2); prior Dialysis with end stage renal disease (coeff: 0.7, 95% CI 0.1-1.1); prior use of Carbapenems (coeff: 1.3, 95% CI 0.3-2.3) and Stay in the ICU for more than 5 days (coeff: 2.4, 95% CI 1.6-3.2). It was validated prospectively in a subsequent cohort (n = 408) and the area-under-the-curve (AUC) of the GSDCS score for predicting nosocomial ICU acquired RGNB infection and bacteremia was 0.77 (95% CI 0.68-0.89 and 0.78 (95% CI 0.69-0.89) respectively. The GSDCS (0-4.3) score clearly differentiated the low (0-1.3), medium (1.4-2.3) and high (2.4-4.3) risk patients, both for RGNB infection (p:0.003) and bacteremia (p:0.009).

Conclusion

GSDCS is a simple bedside clinical score which predicts RGNB infection and bacteremia with high predictive value and differentiates low versus high risk patients. This score will help clinicians to choose appropriate, timely targeted antibiotic therapy and avoid exposure to unnecessary treatment for patients at low risk of nosocomial RGNB infection. This will reduce the selection pressure and help to contain antibiotic resistance in ICUs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0615-z) contains supplementary material, which is available to authorized users.

Risk of acquiring extended-spectrum β-lactamase-producing Klebsiella species and Escherichia coli from prior room occupants in the intensive care unit

OBJECTIVE. To quantify the association between admission to an intensive care unit (ICU) room most recently occupied by a patient positive for extended-spectrum β-lactamase (EBSL)-producing gram-negative bacteria and acquisition of infection or colonization with that pathogen. DESIGN. Retrospective cohort study. SETTING AND PATIENTS. The study included patients admitted to medical and surgical ICUs of an academic medical center between September 1, 2001, and June 30, 2009. METHODS. Perianal surveillance cultures were obtained at admission to the ICU, weekly, and at discharge from the ICU. Patients were included if they had culture results that were negative for ESBL-producing gram-negative bacteria at ICU admission and had an ICU length of stay longer than 48 hours. Pulsed-field gel electrophoresis (PFGE) was performed on ESBL-positive isolates from patients who acquired the same bacterial species (eg, Klebsiella species or Escherichia coli) as the previous room occupant. RESULTS. Among 9,371 eligible admissions (7,651 unique patients), 267 (3%) involved patients who acquired an ESBL-producing pathogen in the ICU; of these patients, 32 (12%) were hospitalized in a room in which the prior occupant had been positive for ESBL. Logistic regression results suggested that the prior occupant's ESBL status was not significantly associated with acquisition of an ESBL-producing pathogen (adjusted odds ratio, 1.39 [95% confidence interval, 0.94-2.08]) after adjusting for colonization pressure and antibiotic exposure in the ICU. PFGE results suggested that 6 (18%) of 32 patients acquired a bacterial strain that was the same as or closely related to the strain obtained from the prior occupant. CONCLUSIONs. These data suggest that environmental contamination may not play a substantial role in the transmission of ESBL-producing pathogens among ICU patients. Intensifying environmental decontamination may be less effective than other interventions in preventing transmission of ESBL-producing pathogens.

Antimicrobial use and resistance among Gram-negative bacilli in an Italian intensive care unit (ICU)

Gram-negative bacilli antimicrobial resistance remains a significant problem for patients in the intensive care unit (ICU). We performed a retrospective analysis of microbiological data and antibiotic consumption over a 4-year period (2000-2003) in an Italian ICU. Pseudomonas aeruginosa and Klebsiella pneumoniae represented approximately 40% of all isolates. The most significant trend in antimicrobial use was an increase in use of 3(rd )generation cephalosporins, imipenem, and ciprofloxacin. A significant trend toward an increase in resistance rates to piperacillin, 3( rd )generation cephalosporins and ciprofloxacin was observed for K. pneumoniae and a positive correlation between resistance and drug-usage was evident for K. pneumoniae and piperacillin, cefotaxime, ceftazidime, cefepime, and ciprofloxacin, but not for piperacillin/tazobactam. No statistically significant correlations were evidenced for P. aeruginosa. Trends in resistances were studied also for Serratia spp and Proteus spp. Isolation rates of extended-spectrum beta-lactamase (ESBL)-producing strains in pathogens studied were high, especially for K. pneumoniae (72%, 160/222) and Proteus spp (41%, 18/43). In conclusion, the study showed high resistance among Gram-negative organisms isolated in the ICU and significant ESBL production. A significant correlation between antibiotic consumption and increasing resistance was evident for K. pneumoniae.

Frequency and predictors of colonization of the respiratory tract by VIM-2-producing Pseudomonas aeruginosa in patients of a newly established intensive care unit

The aim of this study was to examine the frequency and predictors of colonization of the respiratory tract by metallo-beta-lactamase (MBL)-producing Gram-negative bacteria in patients admitted to a newly established intensive care unit (ICU) of a tertiary care hospital. Specimens of tracheobronchial aspirates for microbiological studies were obtained every day for the first 3 days of the ICU stay and subsequently every third day for the rest of the ICU stay. PCR analysis and nucleotide sequencing were performed to identify bacteria that had MBL genes. Thirty-five patients (20 male, 15 female) were hospitalized during the initial 3 month period of functioning of the ICU. Colonization of the lower respiratory tract by Gram-negative bacteria was found in 29 of 35 patients (83 %) during the first 6-20 days (median 13 days) following admission to the ICU (13 patients with Acinetobacter baumannii, ten with Pseudomonas aeruginosa, three with Enterobacter aerogenes, two with Klebsiella pneumoniae and one with Stenotrophomonas maltophilia). Six of 29 patients (21 %) colonized with Gram-negative bacteria had bla(VIM-2)-positive P. aeruginosa isolates; one of these patients developed clinical infection due to this micro-organism. Previous use of carbapenems (P=0.01) or other beta-lactams (P=0.03), as well as a stay in the ICU of >20 days (P<0.001), were associated with colonization with bla(VIM-2)-producing P. aeruginosa. In conclusion, colonization by Gram-negative bacteria of the respiratory tract of patients in this newly established ICU was common (83 %). Use of beta-lactams, including carbapenems, was associated with subsequent colonization of the respiratory tract with MBL-positive P. aeruginosa.

Red blood cell transfusions and nosocomial infections in critically ill patients

OBJECTIVE

A previous retrospective evaluation of Project Impact data demonstrated an association between red blood cell transfusions, nosocomial infections, and poorer outcomes in critically ill patients, independent of survival probability or patient age. The objective of this study was to determine whether transfused patients, independent of survival probability based on Mortality Prediction Model scores, have higher nosocomial infection rates, longer intensive care unit and hospital lengths of stay, and higher mortality rates than nontransfused patients.

DESIGN

Prospective, observational, cohort study.

SETTING

A single-center, mixed medical/surgical, closed intensive care unit.

PATIENTS

: Adults admitted to St. John's Mercy Medical Center between August 2001 and June 2003 (n = 2,085) were enrolled using Project Impact software. Both nonoperative and postoperative populations were represented, and transfusion decisions were made independently of patient study inclusion. Patients whose nosocomial infection was diagnosed before transfusion were counted as nontransfused.

INTERVENTIONS

: None.

MEASUREMENTS AND MAIN RESULTS

Nosocomial infections, mortality rates, and intensive care unit and hospital length of stay were the main outcome measures. Of the 2,085 patients enrolled, 21.5% received red blood cell transfusions. The posttransfusion nosocomial infection rate was 14.3% in 428 evaluable patients, significantly higher than that observed in nontransfused patients (5.8%; p < .0001, chi-square). In a multivariate analysis controlling for patient age, maximum storage age of red blood cells, and number of red blood cell transfusions, only the number of transfusions was independently associated with nosocomial infection (odds ratio 1.097; 95% confidence interval 1.028-1.171; p = .005). When corrected for survival probability, the risk of nosocomial infection associated with red blood cell transfusions remained statistically significant (p < .0001). Leukoreduction tended to reduce the nosocomial infection rate but not significantly. Mortality and length of stay (intensive care unit and hospital) were significantly higher in transfused patients, even when corrected for illness severity.

CONCLUSIONS

Red blood cell transfusions should be used sparingly, bearing in mind the potential risks of infection and poor outcomes in critically ill patients.

Antibiotic Resistance Pattern Among Aerobic Gram Negative Bacilli Isolated from Patients in Intensive Care Units

To study the antimicrobial resistance pattern of aerobic Gram-negative bacilli isolated from patients in intensive care units in Hamad Medical Corporation, 108 non-duplicate isolates from 60 patients with nosocomial infections were determined by Vitek machine. The minimal inhibitory concentration of 14 antimicrobials was determined by E-test and results were interpreted according to the National Committee for Clinical Laboratory Standards guidelines. The most common species was Pseudomonas aeruginosa High levels of resistance were seen to second and third generation cephalosporins, piperacillin, fi-lactam Ji-lactamase inhibitors combinations, and gentamicin. The most active agents were amikacin, meropenem and imipenem (resistance 19%, 19%, 20% respectively). We conclude that second and third generation cephalosporins, piperacillin, fi-lactam/fi-lactamase inhibitors combinations and gentamicin are not suitable drugs for empirical monotherapy for aerobic Gram-negative infections in intensive care units in Qatar.

Outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit linked to artificial nails

BACKGROUND

From April to June 2001, an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae infections was investigated in our neonatal intensive care unit.

METHODS

Cultures of the gastrointestinal tracts of patients, the hands of healthcare workers (HCWs), and the environment were performed to detect potential reservoirs for ESBL-producing K. pneumoniae. Strains of K. pneumoniae were typed by pulsed-field gel electrophoresis using XbaI. A case-control study was performed to determine risk factors for acquisition of the outbreak clone (clone A); cases were infants infected or colonized with clone A and controls (3 per case) were infants with negative surveillance cultures.

RESULTS

During the study period, 19 case-infants, of whom 13 were detected by surveillance cultures, harbored clone A. The overall attack rate for the outbreak strain was 45%; 9 of 19 infants presented with invasive disease (n = 6) or developed invasive disease (n = 3) after colonization was detected. Clone A was found on the hands of 2 HCWs, 1 of whom wore artificial nails, and on the designated stethoscope of a case-infant. Multiple logistic regression analysis revealed that length of stay per day (odds ratio [OR], 1.05; 95% confidence interval [CI95], 1.02 to 1.09) and exposure to the HCW wearing artificial fingernails (OR, 7.87; CI95, 1.75 to 35.36) were associated with infection or colonization with clone A.

CONCLUSION

Short, well-groomed, natural nails should be mandatory for HCWs with direct patient contact

Smoothing a discrete hazard function for the number of patients colonized with Methicillin-resistantStaphylococcus Aureus in an intensive care unit

A new method for estimating the time to colonization of Methicillin-resistant Staphylococcus Aureus (MRSA) patients is developed in this paper. The time to colonization of MRSA is modelled using a Bayesian smoothing approach for the hazard function. There are two prior models discussed in this paper: the first difference prior and the second difference prior. The second difference prior model gives smoother estimates of the hazard functions and, when applied to data from an intensive care unit (ICU), clearly shows increasing hazard up to day 13, then a decreasing hazard. The results clearly demonstrate that the hazard is not constant and provide a useful quantification of the effect of length of stay on the risk of MRSA colonization which provides useful insight.

Attributable costs and length of stay of an extended-spectrum beta-lactamase-producing Klebsiella pneumoniae outbreak in a neonatal intensive care unit

OBJECTIVES

To determine the costs of the interventions aimed at controlling the 4-month outbreak and to determine the attributable length of stay (LOS) associated with infection and colonization with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae.

DESIGN

A retrospective cost analysis was conducted from the hospital perspective. A micro-costing approach was employed. The LOS of four groups of hospitalized patients were compared with each other. National Perinatal Information Center criteria were used to stratify infants for severity of risk. The LOS of each group was compared with that of a national sample of similarly stratified infants.

SETTING

A level III-IV, 45-bed neonatal intensive care unit.

PATIENTS

Infant groups were infected (n = 8), colonized (n = 14), concurrent cohort (n = 54), and prior cohort (n = 486).

RESULTS

The cost of the outbreak totaled 341,751 dollars. The largest proportion of costs was related to healthcare worker time providing direct patient care (2,489 hours at a cost of 146,331 dollars). Infected and colonized neonates had longer LOS than either the concurrent cohort or the prior cohort (P < .001). Compared with the national sample, infected infants had a 48.5-day longer mean LOS (95% confidence interval [CI95], 1.7 to 95.2), whereas the prior cohort's mean LOS was 6 days shorter (CI95, -9.4 to -2.9).

CONCLUSIONS

This study increases the understanding of the burden of these multidrug-resistant organisms. Further research is needed to estimate the societal costs of these infections and the cost-effectiveness of preventive interventions.

The use of economic modeling to determine the hospital costs associated with nosocomial infections

Hospital-associated infection is well recognized as a patient safety concern requiring preventive interventions. However, hospitals are closely monitoring expenditures and need accurate estimates of potential cost savings from such prevention programs. We used a retrospective cohort design and economic modeling to determine the excess cost from the hospital perspective for hospital-associated infection in a random sample of adult medical patients. Study patients were classified as being not infected (n=139), having suspected infection (n=8), or having confirmed infection (n=17). Severity of illness and intensive unit care use were both independently associated with increased cost. After controlling for these confounding effects, we found an excess cost of $6767 for suspected infection and $15,275 for confirmed hospital-acquired infection. The economic model explained 56% of the total variability in cost among patients. Hospitals can use these data when evaluating potential cost savings from effective infection-control measures.

Long-term antibiotic resistance surveillance of gram-negative pathogens suggests that temporal trends can be used as a resistance warning system

Antibiotic resistance among Gram-negative bacteria and antibiotic consumption were investigated at the Karolinska Hospital, Stockholm, Sweden over a 12-y period. The investigation showed an increase in ciprofloxacin resistance of Escherichia coli from 0% in 1991 to 7% in 1997 and to 11% in 1999. Resistance among Pseudomonas aeruginosa isolates to ciprofloxacin increased from 2.5% in 1991 to 9.0% in 1997 and to 13% in 1999. Resistance levels for norfloxacin showed the same high statistical significance in terms of the temporal trend. A more detailed analysis showed higher resistance against norfloxacin in specific wards. Relationships between antibiotic use and antibiotic susceptibility showed different patterns. The increased ciprofloxacin resistance of E. coli and P. aeruginosa during the study period was paralleled by an increased consumption of quinolones. During the 12-y study period the total use of cephalosporins increased 2.5-fold, while the levels of E. coli resistance to cefuroxime and cefotaxime remained stable. A third pattern was seen with trimethoprim-sulfamethoxazole, namely increasing resistance of E. coli as the use of trimethoprim-sulfamethoxazole declined. The analysis of resistance levels and antibiotic consumption in the present study suggests different mechanisms for the increased resistance. The significant trend of increased resistance to antibiotics over time constitutes an important warning system.

Advances in the research and development of chemotherapeutic agents for respiratory tract bacterial infections

The activity of existing antibiotics is diminishing due to the increasing number of resistant strains and by the increase of infections with naturally resistant microorganisms. New agents are urgently needed to meet this challenge and the molecular strategies adopted for the discovery of these compounds must focus on minimizing the emergence of future resistance to them. Novel compounds can be grouped on the basis of their mechanism of action: inhibitors of nucleic acid synthesis (fluoroquinolones), inhibitors of protein synthesis (ketolides, oxazolidinones, streptogramins, and glycylcyclines), inhibitors of peptidoglycan synthesis (beta-lactams and glycopeptides), and agents interfering with membrane function (cationic peptides, and lipopeptides). Regarding the agents that are already in the research and development pipeline, only the oxazolidinones, the cationic peptides and the lipopeptide antibiotics can be truly considered as structurally novel inhibitors because the other agents are analogues of existing compounds that have been in use for many years.

Etiology of fever and opportunities for reduction of antibiotic use in a pediatric intensive care unit

OBJECTIVE

To determine the cause of fever in critically ill children and to identify opportunities for reducing antibiotic use in this population.

DESIGN

Prospective case series.

SETTING

A tertiary-care medical-surgical pediatric intensive care unit (PICU).

PATIENTS

Children admitted to the PICU who experienced fever (axillary temperature >38.3 degrees C).

MEASUREMENTS

Consecutive children who were febrile at any point in their PICU stay were investigated over two winter seasons. Etiology of the fever was determined by physical examination and routine microbiology and radiographic tests. Three subgroups were reviewed to approximate the number of antibiotic-days that could have been reduced; namely, those with an indeterminate source, those with a documented viral infection, and those receiving a prolonged course of antibiotics. A set of standards reflecting common antibiotic use then was applied to these three patient groups.

RESULTS

Of 211 subjects, the majority (83.3%) had either a definitive or suspected focus for their fever, and nearly all of these patients were judged to have an infectious etiology. The study population received a total of 2,036 antibiotic-days. Despite the high incidence of infectious causes of fever in our subjects, however, approximately 15% of total antibiotic-days could have been reduced by applying common-use standards.

CONCLUSIONS

Fever in the PICU was usually of defined focus and infectious in origin. However, among febrile patients in the PICU, substantial opportunity exists for reduction of antibiotic use. Trials determining the safety of antibiotic reduction in this population should be pursued vigorously.

Susceptibility Patterns of Select Gram-Negative Organisms after a Formulary Switch from Ceftazidime to Cefepime

Objective:

To document changes in susceptibility patterns of gram-negative organisms, including Pseudomonas aeruginosa, Enterobacter aerogenes, Acinetobacter calcoaceticus, and Serratia marcescens after a formulary switch from ceftazidime to cefepime.

Design, Setting:

Retrospective, observational study in a tertiary care, university teaching hospital.

Participants:

Adult surgical patients with culture and susceptibility data.

Main Outcome Measures:

Percent susceptible and median minimum inhibitory concentration values were evaluated for select gram-negative organisms from culture and susceptibility results. The time periods of one year before and two years after the formulary change were evaluated. Duplicate isolates were excluded. Different culture sites of infection were assessed for P. aeruginosa, including blood, urine, and lung.

Results:

A total of 957 samples from 489 patients were included. Susceptibility results after the formulary switch favored ceftazidime over cefepime for P. aeruginosa (79% vs. 54%; n = 485) and A. calcoaceticus (65% vs. 29%; n = 140). However, cefepime demonstrated greater kill rate with E. aerogenes isolates compared with ceftazidime (95% vs. 69%; n = 208). Susceptibility results were comparable with S. marcescens (100% for cefepime vs. 98% for ceftazidime). P. aeruginosa results from isolates taken from different culture sites did not differ from the overall results, as susceptibility was higher for ceftazidime compared with cefepime for all culture sites.

Conclusions:

Susceptibility to cefepime and ceftazidime is organism-specific; therefore, it may be appropriate to include both agents on the formulary and/or implement an antibiotic rotation policy.

Systemic antibiotics fail to clear multidrug-resistant Klebsiella from a pediatric ICU

STUDY OBJECTIVES

To determine the magnitude of infection rate and antimicrobial resistance in a pediatric ICU (PICU), and to evaluate the efficacy of using broad-spectrum antibiotics.

DESIGN

A 3-month, prospective, observational cohort audit.

SETTING

A 12-bed tertiary, referral PICU.

PATIENTS OR PARTICIPANTS

All children admitted to the PICU for > 72 h.

INTERVENTIONS

Surveillance cultures of throat and rectum on admission and once weekly thereafter.

MEASUREMENTS AND RESULTS

Of the 150 admissions during the 3-month period, a total of 52 patients (24 girls and 28 boys) requiring mechanical ventilation for a minimum of 3 days were enrolled in the audit. The median age and interquartile range (IQR) was 17 months (IQR, 5.8 to 63); length of stay, 6.5 days (IQR, 4 to 13); ventilation days, 5 (IQR, 3 to 11); pediatric risk of mortality score, 14 (IQR, 9 to 19); and risk of mortality, 0.03 (IQR, 0.014 to 0.087). Fifteen patients (29%) developed 21 infections, mainly lower-airway infections and septicemias. Of the 52 children, 7 children carried multidrug-resistant bacteria and 3 patients progressed to develop four infections with those resistant bacteria. Of the seven carriers, six patients carried gentamicin-resistant Klebsiella. Methicillin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae and gentamicin-resistant Pseudomonas aeruginosa each were carried by one child. Six of those nine resistant isolates were present in the admission flora. Despite the potent combination of piperacillin/tazobactam and amikacin, three children acquired the multidrug-resistant Klebsiella while in the PICU and became nosocomial carriers.

CONCLUSIONS

Only surveillance cultures allow the distinction between import of multidrug-resistance and resistant bacteria acquired while in PICU. In this study, two thirds of the resistant isolates were imported. The introduction of newer potent systemic antibiotic combinations failed to control the endemic reservoir of multidrug-resistant Klebsiella and suggests that such policies have little impact.

Hospital-acquired pneumonia: risk factors, microbiology, and treatment

Pneumonia complicates hospitalization in 0.5 to 2.0% of patients and is associated with considerable morbidity and mortality. Risk factors for hospital-acquired pneumonia (HAP) include mechanical ventilation for > 48 h, residence in an ICU, duration of ICU or hospital stay, severity of underlying illness, and presence of comorbidities. Pseudomonas aeruginosa, Staphylococcus aureus, and Enterobacter are the most common causes of HAP. Nearly half of HAP cases are polymicrobial. In patients receiving mechanical ventilation, P aeruginosa, Acinetobacter, methicillin-resistant S aureus, and other antibiotic-resistant bacteria assume increasing importance. Optimal therapy for HAP should take into account severity of illness, demographics, specific pathogens involved, and risk factors for antimicrobial resistance. When P aeruginosa is implicated, monotherapy, even with broad-spectrum antibiotics, is associated with rapid evolution of resistance and a high rate of clinical failures. For pseudomonal HAP, we advise combination therapy with an antipseudomonal beta-lactam plus an aminoglycoside or a fluoroquinolone (eg, ciprofloxacin).

Antimicrobial resistance of gram-negative isolates from intensive care units in Turkey: comparison to previous three years

Resistance rates to selected antibiotics of gram-negative bacteria isolated from intensive care units (ICU) of 16 Turkish hospitals during 1998 were evaluated and compared to data from the previous 3 years. Antibiotic susceptibilities to imipenem, ceftazidime, ceftazidime-clavulanate, cefoperazone-sulbactam, ceftriaxone, cefepime, cefodizime, cefuroxime, piperacillin-tazobactam, ticarcillin-clavulanate, gentamicin, amikacin and ciprofloxacin were determined by Etest. A total of 1,404 isolates from 1,060 patients were collected, mainly from urinary and respiratory tracts. As in the previous 3 years, Pseudomonas spp. was the most frequently isolated gram-negative species (29.7%), followed by Escherichia coli, Acinetobacter and Klebsiella spp. Imipenem was the most active in vitro agent (73.4% susceptible), followed by ciprofloxacin (60.6%), cefoperazone-sulbactam (58.7%), cefepime (56.7%), piperacillin-tazobactam (55.0%) and amikacin (54.7%). In 1996, a decline in susceptibility rates of all antibiotics was evident. With the exception of imipenem, resistance to which remained stable, rates somewhat increased in 1997. In 1998, susceptibility to imipenem and cefepime remained stable, amikacin resistance tended to increase and susceptibility rates to other antibacterials showed a favorable increase. These results may in part be due to the implementation of a surveillance program and increased understanding of the magnitude of the resistance problem.

Intensive care unit design and environmental factors in the acquisition of infection

The incidence of infection in the intensive care unit (ICU) is one of the highest in the hospital and yet facilities to prevent infection are often inadequate in this important clinical area. Many antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), Serratia marcescens and vancomycin-resistant enterococci (VRE), may survive and persist in the environment leading to recurrent outbreaks. A number of professional and scientific bodies in the UK, the USA and Europe have published guidelines on the design and layout of ICUs. All emphasize the importance of adequate isolation facilities (at least one cubicle for every six beds), sufficient space around each bed (20 m2), wash hand basins between every other bed, ventilation including positive and negative pressure ventilation for high risk patients and sufficient storage and utility space. Common sense and considerations of safety and comfort should guide decisions on floors, walls etc. Appropriate cleaning and disinfection programmes are essential to render the ICU relatively pathogen free and compliance with handwashing is imperative in minimizing infection in this high-risk area. Infection control teams should support ICU personnel in their efforts to upgrade facilities and help ensure that this is a priority when resources are limited.

Assessment of the relationship between antimicrobial usage and susceptibility: differences between the hospital and specific patient-care areas

Current evidence suggests that controlling antibiotic resistance requires the monitoring of both susceptibility trends and antimicrobial usage within specific patient-care areas of the hospital. To assess the differences between antimicrobial usage-versus-susceptibility relationships found in the hospital and those relationships found in specific patient-care areas, susceptibility and antimicrobial usage data collected over a 5-year period (1992-1996) at the Medical University of South Carolina were analyzed. For each area, the relationship between drug use and susceptibility was analyzed for 8 gram-negative organisms with respect to 19 different agents and for 3 staphylococci with respect to 10 agents with use of simple linear regression. The relationships found in the hospital had a poorer overall agreement with the relationships found in the intensive care units (ICUs; <20%) than they did with the relationships found in the non-ICUs ( approximately 65%). Surveillance should include both susceptibility and drug usage patterns in individual areas within an institution.

Pulsed-field gel electrophoresis is a useful tool in the monitoring of methicillin-resistant Staphylococcus aureus epidemic outbreaks in the intensive care unit

We wished to determine how pulsed-field gel electrophoresis may be of use in monitoring methicillin-resistant Staphylococcus aureus (MRSA) outbreaks in the intensive care unit (ICU). A retrospective epidemiological analysis was conducted. All 27 ICU patients and 11 patients from other hospital wards from whom MRSA was isolated over a one year period were included in the study. Seventeen of the 27 ICU MRSA isolates were analysed by pulsed-field gel electrophoresis for clonality and compared with the 11 other hospital isolates genotypes over the same period. During three MRSA outbreaks, five MRSA genotypes were identified in ICU whilst the same five genotypes and three additional were found in the rest of the hospital. Pulsed-field gel electrophoresis analysis was useful in identifying clonality of ICU MRSA infections and establishing that they were imported from hospital wards, rather than arising de novo in ICU. We were further able to identify clonal clusters within the unit linked by temporal and geographical proximity, suggestive of cross-infection. Pulsed-field gel electrophoresis typing might be additionally useful in tracing the source of human and/or environmental factors if a genotype were persistently identified.

Colonization with broad-spectrum cephalosporin-resistant gram-negative bacilli in intensive care units during a nonoutbreak period: prevalence, risk factors, and rate of infection

OBJECTIVE

To define the epidemiology of broad-spectrum cephalosporin-resistant gram-negative bacilli in intensive care units (ICUs) during a nonoutbreak period, including the prevalence, the risk factors for colonization, the frequency of acquisition, and the rate of infection.

DESIGN

Prospective cohort study.

SETTING

Tertiary care hospital.

PATIENTS

Consecutive patients admitted to two surgical ICUs.

MAIN OUTCOME MEASUREMENTS

Serial patient surveillance cultures screened for ceftazidime (CAZ) resistance, antibiotic and hospital exposure, and infections.

RESULTS

Of the 333 patients enrolled, 60 (18%) were colonized with CAZ-resistant gram-negative bacilli (CAZ-RGN) at admission. Clinical cultures detected CAZ-RGN in only 5% (3/60) of these patients. By using logistic regression, CAZ-RGN colonization was associated with duration of exposure to cefazolin (odds ratio, 10.3; p < or = .006) and to broad-spectrum cephalosporins/penicillins (odds ratio, 2; p < or = .03), Acute Physiology and Chronic Health Evaluation III score (odds ratio, 1.2; p < or = .008), and previous hospitalization (odds ratio, 3.1; p < or = .006). Of the 100 patients who remained in the surgical ICU for > or = 3 days, 26% acquired a CAZ-RGN. Of the 14 infections caused by CAZ-RGN, 11 (79%) were attributable to the same species present in surveillance cultures at admission to the surgical ICU.

CONCLUSIONS

Colonization with CAZ-RGN was common and was usually not recognized by clinical cultures. Most patients colonized or infected with CAZ-RGN had positive surveillance cultures at the time of admission to the surgical ICU, suggesting that acquisition frequently occurred in other wards and institutions. Patients exposed to first-generation cephalosporins, as well as broad-spectrum cephalosporins/penicillins, were at high risk of colonization with CAZ-RGN. Empirical treatment of nosocomial gram-negative infections with broad-spectrum cephalosporins, especially in the critically ill patient, should be reconsidered.

Overview of resistance in the 1990s

The tremendous therapeutic advantage afforded by antibiotics is being threatened by the emergence of increasingly resistant strains of microbes. Selective pressure favoring resistant strains arises from misuse and overuse of antimicrobials (notably extended-spectrum cephalosporins), increased numbers of immunocompromised hosts, lapses in infection control, increased use of invasive procedures and devices, and the widespread use of antibiotics in agriculture and animal husbandry. Outside the hospital, penicillin-resistant Streptococcus pneumoniae is of greatest concern; recent reports also indicate the appearance of outpatient methicillin-resistant Staphylococcus aureus (MRSA) infections. MRSA is a significant problem in the hospital, as are vancomycin-resistant Enterococcus, oxacillin-resistant S aureus, and multidrug-resistant Gram-negative bacilli. Owing to the high rate of antibiotic use and other risk factors, a person is more likely to acquire an antibiotic-resistant infection in the ICU than anywhere else, either inside or outside the hospital. Responsible antibiotic use and stringent infection-control policies are needed to discourage the development of resistant strains.

Comparative in vitro activity of meropenem versus other routinely used antimicrobials against 18632 aerobic bacteria tested in 92 German centers

The in vitro antibacterial activity of meropenem and up to 26 other antibiotics was compared under routine conditions at 92 German centers from March to June 1995 with use of the agar diffusion method against 18632 recent isolates from ICU--hemato-oncology--and pediatric patients. Overall, meropenem was the most active drug exhibiting a higher activity against gram-negative aerobes than imipenem, but somewhat less active against staphylococci and enterocooci. The overall resistance rates of most antibiotics tested was higher compared to the recently published surveillance data of the Paul-Ehrlich-Society in Germany. The main reason for this discrepancy is the higher percentage of test strains which were recovered from intensive care unit patients in the present study. These data confirm similar results from the USA and underscore the pressing need for the implementation of a nationwide antimicrobial surveillance system which is risk-stratified by hospital size, ICU- versus non-ICU-patients, and body site from which the isolates are recovered.

A computer simulation model for the spread of nosocomial infections caused by multidrug-resistant pathogens

A Monte Carlo simulation model was developed for the spread of antibiotic-resistant bacteria in hospital units. The model allows for the representation of every patient and staff member. Staff-patient interactions, staff handwashing compliance, admission of colonized patients, and antibiotic use are included in the model. The simulation model provides colonization curves for patients and staff and offers the possibility of simulating different kinds of hospital units. Simulation of the spread of an antibiotic-resistant pathogen in an intensive care unit was performed. We studied the impact of handwashing compliance on colonization. The importance of handwashing in preventing colonization and the influence of admission of colonized patients in perpetuating an epidemic were confirmed by the model. The model offers a new approach to modeling the spread of nosocomial pathogens in hospital units. It allows one to study the impact of infection control measures and represents a valuable educational tool for staff.

The contribution of antibiotic use on the frequency of antibiotic resistance in hospitals

Abundant evidence suggests a relationship between antibiotic resistance and use, including animal models, consistent associations between resistance and antibiotic use in hospitals, concomitant variation in resistance as antibiotic use varies, and a dose-response relationship for many pathogen/antibiotic combinations. Much of the evidence has come from studies performed in single hospitals. Most multicentre studies on resistance have not included data on antibiotic usage. Despite this substantial body of evidence, some studies have failed to demonstrate an association between antibiotic resistance and use, suggesting other contributing factors such as cross-transmission, inter-hospital transfer of resistance, a community contribution to resistance, or a complex relationship between resistance and the use of a variety of antibiotics. A multicentre study, project ICARE (Intensive Care Antimicrobial Resistance Epidemiology), implemented in 1994 by Centers for Disease Control and Prevention and Rollins School of Public Health, Emory University, has found dramatic differences in the patterns of antibiotic usage and resistance in US hospitals. The findings suggest that antibiotic usage is the major risk factor in development of antibiotic resistance in hospitals but the relationship can be complex with additional factors involved. Understanding the problem of antibiotic resistance in a hospital cannot be achieved without knowledge of the hospital's pattern of antibiotic use.

Vancomycin resistance: when failure becomes an opportunity for leadership

OBJECTIVE

To discuss the emergence of the enterococci as significant nosocomial pathogens and reports of glycopeptide resistance as demonstrating the failure of healthcare professionals to limit the clinical impact of these organisms.

BACKGROUND

The enterococci have long occupied a peculiar position in medical and surgical patients. A component of the normal gastrointestinal tract, these organisms exhibit little overt pathogenicity in healthy hosts, but are frequently recovered in patients with severe debilitative or immunosuppresive disorders. While the enterococci have always demonstrated intrinsic resistance to a broad range of antiinfective agents, recent findings of moderate to high-level glycopeptide resistance potentially threaten the limited therapeutic options for methicillin-resistant gram-positive cocci.

FINDINGS

The emergence and dissemination of vancomycin-resistant enterococci are signs of much greater problems, which include incomplete success of formulary controls, unreliable detection and identification of resistant microorganisms within the hospital environment, and poor fundamental infection control practices by all healthcare professionals.

CONCLUSIONS

The Hospital Infection Control Practices. Advisory Committee Recommendations for the Prevention and Spread of Vancomycin Resistance are an important step in resolving these issues through the elements of collegiality and shared leadership.