汕头地区医院感染多重耐药铜绿假单胞菌的基因型特征分析

目的了解汕头地区ICU和非ICU医院感染多重耐药铜绿假单胞菌分离株的基因型特征。方法收集汕头地区两家三级甲等医院的医院感染铜绿假单胞菌菌株,对这些菌株的耐药性和基因型进行分析。采用纸片扩散法进行药敏试验,脉冲场凝胶电泳法对多重耐药菌株进行基因分型,电泳结果用BionumericsV4.0软件进行聚类分析。结果共分离到132株铜绿假单胞菌,其中45株分离自ICU,87株来自非ICU病房。132株菌株中,有46株多重耐药菌（耐三种抗菌素或以上）。对46株多重耐药菌（25株来自ICU,21株来自非ICU病房）进行脉冲场凝胶电泳,结果显示来自ICU病房的25株菌株具有较高程度的同源性,而来自非ICU病房的菌株则具有明显的基因多态性。结论交叉感染是ICU多重耐药铜绿假单胞菌医院感染的重要传播途径。     

Use of surveillance cultures and enteral vancomycin to control methicillin-resistant Staphylococcus aureus in a paediatric intensive care unit

This study assessed the effects of throat and gut surveillance, combined with enteral vancomycin, on gut overgrowth, transmission of methicillin-resistant Staphylococcus aureus (MRSA), infections and mortality in patients admitted to a paediatric intensive care unit (PICU). A 4-year prospective observational study was undertaken with 1241 children who required ventilation for >or=4 days. Patients identified as MRSA carriers following surveillance cultures of throat and rectum received enteral vancomycin. Twenty-nine (2.4%) children carried MRSA, 19 on admission and nine during treatment in the PICU; one patient was not able to be evaluated. Overgrowth was present in 22 (75%) of the carriers. Ten (0.8%) children developed 21 MRSA infections (15 exogenous infections in eight children at a median of 8 days (IQR 3-10.5); five primary endogenous infections at a median of 3 days (IQR 1-25) in three children when they were in overgrowth status; one child developed both types of infection). Enteral vancomycin reduced gut overgrowth significantly, completely preventing secondary endogenous infections. Transmission occurred on nine occasions over a period of 4 years. Four patients died, two (5.9%) with MRSA infection, giving a mortality (11.8%) similar to the study population (9.8%). No emergence of vancomycin-resistant enterococci or S. aureus with intermediate susceptibility to vancomycin was detected. A policy based on throat and gut surveillance, combined with enteral vancomycin, for critically-ill children who were MRSA carriers was found to be effective and safe, and challenges the recommended guidelines of nasal swabbing followed by topical mupirocin.     

An outbreak of hospital-acquired Pseudomonas aeruginosa infection caused by contaminated bottled water in intensive care units.

This study describes an outbreak of Pseudomonas aeruginosa infections caused by contaminated bottled still water (BSW) in six intensive care units (ICUs) of a German university hospital. Clinical and environmental samples from these units were cultured and genotyped by amplified fragment-length polymorphism and pulsed-field gel electrophoresis analysis. Microbiological results were reviewed on a weekly basis to determine the number of P. aeruginosa infections and colonisations of ICU patients. Clinical specimens from 19 ICU patients--15 infections and four colonisations--yielded the same strain of P. aeruginosa. Furthermore, four of 103 environmental samples also yielded P. aeruginosa. However, only a P. aeruginosa strain isolated from unopened BSW was genetically identical to the P. aeruginosa strain isolated from the patients. In the 42-week period before the outbreak, the mean weekly number of new ICU patients infected or colonised with P. aeruginosa was 46.9 (95% CI 40.7-53.1)/1000 bed-days. During the 6-week period of the outbreak, the weekly number of new patients with P. aeruginosa was 88.9 (95% CI 54.3-122.2)/1000 bed-days. This number returned to the previous level after removal of the BSW. Thus, the microbiological and epidemiological findings revealed that the outbreak was related to BSW contaminated with P. aeruginosa. It was concluded that all untested BSW should be removed from ICUs.     

Muco-cutaneous colonization and nosocomial infections caused by methicillin-resistant Staphylococcus aureus and Acinetobacter baumanii in intensive care patients

This study was designed to assess the frequency and risk factors for colonization with MRSA and A. baumanii in the intensive care unit, and to analyse the relationship between colonization and infection with MRSA or A. baumanii. During a 24-day survey period, colonization was studied weekly with nasal, throat and digit skin swabs; nosocomial infections were routinely monitored according to CDC recommendations. Clinical data and invasive procedures were registered during a one-year non-epidemic period; 103 ICU patients hospitalized for more than 7 days were prospectively included. We investigated acquired colonization and nosocomial infection with SAMR or A. baumanii for 87 patients not colonized by SAMR or A. baumanii on admission. The colonization acquisition rate was 56% for MRSA and 27% for A. baumanii. Infection incidence (cases per 1,000 patient-days) was 6.46 for MRSA and 1.61 for A. baumanii. On univariate analysis, acquired MRSA colonization was associated with longer ICU stays, longer mechanical ventilation and longer central venous catheterization. Multivariate analysis only showed an association with longer ICU stay. Acquired A. baumanii colonization was associated with SAPSII, longer mechanical ventilation, and longer central venous catheterization in univariate analysis. Multivariate analysis only showed an association with SAPSII and longer mechanical ventilation. In this study, SAMR or A. baumanii infections were not associated with colonization or clinical setting or invasive procedures.     

Microbiological surveillance in an intensive care unit of a large Roman hospital

Infection surveillance in ICU is fundamental to monitor endemic rates, to identify outbreaks on-time in order to activate control procedures implementing a correct empirical antibiotic treatment. The data collection surveillance software CIN-20002 was established in the Teaching Hospital Umberto I ICU to monitor the following site-specific infection rates: urinary tract infections (UTI), pneumonia (PNE), blood stream infections (BSI), surgical site infections (SSI). According to CDC definitions all patients developing infection 48 hours or more after ward admission were included. Furthermore risk factors (i.e. age, sex, SAPS II), invasive procedures (i.e. endotracheal intubation, vascular and urinary catheterisation), microbiological isolates and their antibiotic susceptibility were screened. Overall 279 patients (183 men and 96 women) were admitted; age 54,8 20,3 years (mean), SAPS II 44,4 17,1 (mean) and average ward stay 13,3 17,8 days. Results showed a total of 121 infection episodes (56 PNE, 51 BSI, 10 UTI e 4 SSI) in 80 patients (28,7%). Standardized infection rates associated to invasive procedures were: Urinary catheter-associated UTI rate (2.9/1000), Ventilator-associated PNE rate (20.4/1000), Vascular catheter-associated BSI rate (19.1/1000). Among the infected patients the most common microrganisms isolated were P. aeruginosa (31,8%), MRSA (14,8%), A. baumanni (12,5%) e S. maltophilia (8,5%). Considering site-specific infections: PNE (P. aeruginosa 38,3% and MRSA 18,1%), BSI (MR CNS 21,9% and P. aeruginosa 17,2%), UTI (P. aeruginosa 70,0%). The surveillance software CIN-2000 proved to be very accurate, usefull and easy to use. The results showed a high incidence of infections associated to invasive procedures and the presence of multiresistant bacteria     

Outbreak of methicillin-resistant Staphylococcus aureus in general hospital intensive care unit]

Mantes' hospital polyvalent intensive care unit (ICU) experienced an outbreak episode caused by methicillin resistant Staphylococcus aureus (MRSA). Suspicion of physicians was strengthened by observing the weekly reading of multiresistant germs and the significative increase of MRSA carriers incidence rate, compared with the number of admission in the ICU: 5.5% to 11.3%. This outbreak was surprising: it happened immediately after the installation in a new hospital and the reinforcement of nosocomial infection surveillance (systematic screening of every patient admitted to the I.U.C., his isolation if he presents risk factors to multiresistant germs, increasing of handwashing stations). The overlapping period of hospitalisation concerning the 13 patients being reported as SARM carrier, having the same antibiogram, and the epidemic curve suggested a cross contamination. The index case was a MRSA carrier the day of her admission and have had a recent hospitalisation in a high risk unit. MRSA has always been isolated in nasal swab. Six patients among the thirteen carriers developed an infection and have been treated by vancomycin: two systemic infections and four pulmonary infections. The mortality rate was 33% and only one of them seemed to be directly due to MRSA. Area samples were all negative. The clinical staff have been screened with nasal swab. We identified only one nasal MRSA carrier. The pulsed-field gel electrophoresis study showed that 9/11 which have been analysed were identical. This outbreak brought about staff, more sensibilisation to the nosocomial infection and updating of plain hygien rules leaded to its stop five months later.     

Epidemiologic characterization of Pseudomonas aeruginosa in patients with cystic fibrosis

Objective   To determine persistence and variability of colonization with Pseudomonas aeruginosa in cystic fibrosis patients over long time periods, and to look for possible cross-colonization.
Methods   In total, 469 Pseudomonas aeruginosa isolates were obtained from 30 patients during the period from April 1994 to April 1996. The sources were mainly sputum and a few deep throat swabs. All grown strains dissimilar in macromorphology were processed separately. Typing with PFGE was carried out by contour-clamped homogeneous electric field electrophoresis. Genomic DNA was subjected to the rare-cutting restriction enzyme Spe I. For pyocin typing, the procedure described by Fyfe was applied.
Results   After typing with PFGE, we observed 40 restriction profiles. Eighteen different pyocin types were found. The most frequent pyocin type was type 3, followed by types 1 and 5. Twenty-two patients were persistently colonized by one clone specific and different for each patient, and four were co-colonized by a second clone also different for each of these patients. Cross-colonization had apparently been rare in the cystic fibrosis center of Leipzig.
Conclusions   Typing with PFGE is well suited for detailed investigations of colonization with Pseudomonas aeruginosa in cystic fibrosis patients. Pyocin typing can provide additional information for epidemiologic purposes.     

Incidence of and risk factors for community-associated methicillin-resistant Staphylococcus aureus acquired infection or colonization in intensive-care-unit patients

The incidence of and risk factors for acquiring community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) among patients staying in intensive care units (ICUs) remain unclear. We enrolled patients staying in two ICUs at the Far Eastern Memorial Hospital during the period of 1 September 2008 to 30 September 2009 to clarify this issue. Surveillance cultures for MRSA were taken from nostril, sputum or throat, axillae, and the inguinal area in all enrolled patients upon admission to the ICU, every 3 days thereafter, and on the day of discharge from the ICU. For each MRSA isolate, we performed multilocus sequence typing, identified the type of staphylococcal cassette chromosome mec, detected the presence of the Panton-Valentine leukocidin gene, and conducted drug susceptibility tests. Among the 1,906 patients who were screened, 203 patients were carriers of MRSA before their admission to the ICU; 81 patients acquired MRSA during their stay in the ICU, including 31 who acquired CA-MRSA. The incidence rates of newly acquired MRSA and CA-MRSA during the ICU stay were 7.9 and 3.0 per 1,000 patient-days, respectively. Prior usage of antipseudomonal penicillins and antifungals and the presence of a nasogastric tube were found to be independent risk factors for acquiring CA-MRSA during the ICU stay when data for CA-MRSA carriers and patients without carriage of MRSA were compared (P=0.0035, 0.0330, and 0.0262, respectively). Prior usage of carbapenems was found to be a protective factor against acquiring CA-MRSA when data for patients with CA-MRSA and those with health care-associated MRSA acquired during ICU stay were compared (P=0.0240).     

天津地区某基层医院铜绿假单胞菌的5年耐药变迁

目的 观察天津地区某基层医院铜绿假单胞菌的临床分布及其耐药情况和近5年的耐药变化趋势,为临床抗感染治疗的经验用药和合理使用抗生素提供理论依据。方法 收集2013年1月~2017年12月我院住院患者细菌培养标本分离的铜绿假单胞菌,分析其科室分布及菌株对临床常用抗菌药物的耐药率和耐药变迁。结果 5年内共分离到铜绿假单胞菌542株,其分布主要以呼吸内科、ICU以及普通外科为主。铜绿假单胞菌对氨曲南、左氧氟沙星、头孢他啶、亚胺培南、美罗培南、哌拉西林他唑巴坦、阿米卡星的耐药率分别为28.80%、17.30%、15.40%、13.30%、15.30%、8.30%、3.60%。结论 铜绿假单胞菌是基层三级综合医院临床科室最常见的革兰阴性非发酵菌,分离人群主要以呼吸内科、ICU和普通外科为主。我院分离的铜绿假单胞菌对大多数临床常用抗菌药物均有较好的体外敏感性。因此,临床使用这些药物治疗铜绿假单胞菌感染通常可获得良好的疗效。但由于该细菌易产生获得性耐药,且近年来少数抗菌药物的耐药率波动范围较大。因此建议临床医生关注实验室药敏结果报告和细菌耐药监测报告。     

Duration of hospital admission and the need for empirical antipseudomonal therapy

To reduce selective pressure for antimicrobial resistance, empirical use of antipseudomonal antibiotics is often reserved for patients with late-onset hospital-acquired infections. We examined the likelihood of isolating Pseudomonas aeruginosa as a function of time from hospital admission. We conducted a retrospective cohort study of all positive bacterial cultures in a tertiary-care hospital between March 2010 and November 2011. The primary outcome was the proportion of positive cultures yielding P. aeruginosa. Multivariable logistic regression was employed to assess the impact of time from admission on the likelihood of isolating P. aeruginosa, after adjusting for other important risk factors. A total of 7,668 positive cultures were obtained from 4,108 unique patients during the study interval, including 633 (8.3%) yielding P. aeruginosa. The probability of isolating P. aeruginosa increased linearly from 79/2,044 (3.9%) positive cultures obtained on admission to 153/664 (23%) in the 10th week of admission or beyond. The unadjusted odds ratio was 1.002/day (95% confidence interval [CI], 1.0016 to 1.0028; P < 0.0001); the adjusted odds ratio (aOR) was 1.0007/day (95% CI, 1.0001 to 1.0013; P = 0.02). Other important predictors of P. aeruginosa isolation included respiratory specimen type (aOR, 13.8; 95% CI, 9.1 to 21.1), recent hospital admission (aOR,1.8; 95% CI, 1.4 to 2.3), prior P. aeruginosa isolation during current admission (aOR, 4.9; 95% CI, 3.7 to 6.4), and prior antipseudomonal (aOR, 1.9; 95% CI, 1.4 to 2.5) or nonantipseudomonal (aOR, 1.8; 95% CI, 1.4 to 2.4) antibiotic exposure. It was determined that as time from admission increases, there is a linear increase in the likelihood of P. aeruginosa isolation. Any guidelines which distinguish early from late hospital-acquired infection must consider the implications of time point selection on the likelihood of inadequate P. aeruginosa empirical coverage.     

Antimicrobial resistance patterns among aerobic Gram-negative bacilli isolated from patients in intensive care units: results of a multicenter study in Russia

Objective: To determine the antimicrobial resistance patterns among aerobic Gram-negative bacilli isolated from patients in intensive care units (ICUs) in different parts of Russia.
Methods: During 1995–96, 10 Russian hospitals from different geographic areas were asked to submit 100 consecutive Gram-negative isolates from patients with ICU-acquired infections. Minimal inhibitory concentrations (MICs) of 12 antimicrobials were determined by Etest and results were interpreted according to National Committee for Clinical Laboratory Standards (NCCLS) guidelines.
Results: In total, 1005 non-duplicate strains were obtained from 863 patients. The most common species were Pseudomonas aeruginosa (28.8%), Escherichia coli (21.4%), Klebsiella pneumoniae (16.7%), Proteus mirabilis (9.7%), Enterobacter spp. (8.2%) and Acinetobacter spp. (7.7%). High levels of resistance were seen to second- and third-generation cephalosporins, ureidopenicillins, β-lactam/β-lactamase inhibitor combinations and gentamicin. The most active agents were imipenem (no resistance in Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter spp. and Acinetobacter spp., 7% resistance in Pseudomonas aeruginosa ), amikacin (7% resistance in Pseudomonas aeruginosa and Acinetobacter spp., 4% in Enterobacter spp., 1% in Escherichia coli and Proteus mirabilis, no resistance in Klebsiella pneumoniae ) and ciprofloxacin (15% resistance in Pseudomonas aeruginosa, 5% in Enterobacter spp. and Proteus mirabilis, 2% in Klebsiella pneumoniae, 1% in Escherichia coli ).
Conclusions: Second- and third-generation cephalosporins, ureidopenicillins, β-lactam/β-lactamase inhibitor combinations and gentamicin cannot be considered as reliable drugs for empirical monotherapy for aerobic Gram-negative infections in ICUs in Russia.     

2016~2018年某院ICU 医院感染目标性监测及干预

目的 分析我院ICU医院感染现状,为医院感染管理提供依据。方法 制定ICU医院感染目标性监测方案,采用前瞻性监测方法对我院2016~2018年ICU患者进行目标性监测,每季度根据监测结果进行实时干预。结果 通过监测及干预,连续三年ICU医院感染发病率、医院感染例次发病率、日感染发病率、调整医院感染发病率、调整医院感染例次发病率以及调整日感染发病率均呈逐年下降趋势（P＜0.05）。神经系统和呼吸系统疾病类ICU住院患者的医院感染发病率分别为10.83%、3.31%。ICU医院感染部位以呼吸道为主,占70.67%。呼吸机、导尿管、中心静脉导管的使用率分别为33.90%、71.92%、22.73%,三管相关发病率分别为10.00‰、1.49‰、1.81‰。呼吸机使用率与VAP发病率有相关性（r=1.00,P＜0.001）。医院感染前3位病原菌分别为肺炎克雷伯菌（占30.23%）、鲍曼不动杆菌（占23.26%）、铜绿假单胞菌（占10.47%）。结论 持续开展ICU医院感染目标性监测,有利于针对高危因素及薄弱环节及时采取干预措施,从而有效降低医院感染发病率。神经系统疾病类和呼吸系统疾病类患者是院感防控关注的重点人群,器械相关性感染（特别是VAP）、多重耐药菌感染是干预的重点环节。     

Colistin treatment in patients with ICU-acquired infections caused by multiresistant Gram-negative bacteria: the renaissance of an old antibiotic

A retrospective case series study was performed in a 30-bed general intensive care unit (ICU) of a tertiary care hospital to assess the effectiveness and safety of colistin in 43 critically ill patients with ICU-acquired infections caused by multiresistant Gram-negative bacteria. Various ICU-acquired infections, mainly pneumonia and bacteraemia caused by multiresistant strains of Pseudomonas aeruginosa and/or Acinetobacter baumannii, were treated with colistin. Good clinical response (cure or improvement) was noted in 74.4% of patients. Deterioration of renal function occurred in 18.6% of patients during colistin therapy. Nephrotoxicity was elevated significantly in those patients with a history of renal failure (62.5%). All-cause mortality amounted to 27.9%. In this group of critically ill patients, an age of >50 years (OR, 5.4; 95% CI 1.3-24.9) and acute renal failure (OR, 8.2; 95% CI 2.9-23.8) were independent predictors of mortality. Colistin should be considered as a treatment option in critically ill patients with infection caused by multiresistant Gram-negative bacilli.     

Infections in patients after thoracic surgery

Purpose of this paper was estimation of occurrence of postoperative complications caused by most common infection agents. Research covered 1662 hospitalised patients during 2000-2001. Clinical records of patients and results from bacteriological research were analysed. Analysis of etiological agents were based on 779 clinical samples. In postoperative period infection was observed in 138 patients (9.2%). Among them 158 episodes of infection occurred. Totally for 138 patients, 158 infections were observed in postoperative period. 9% of all (1662)-operated patients had postoperative infections. In that number were: 98 (6.5%)--bronchopulmonary infection, 25 (1.7%)--empyema, 21 (1.4%)--wound infections, 10 (0.7%)--urinary tract infection, 4 (0.3%)--sepsis. All those complications caused 14 deaths. CONCLUSIONS: 1. Thoracic surgeries were connected with quite high risk of postoperative infections. 2. The most common postoperative complication was bronchopneumonia. 3. The most common etiological agent in thoracic surgery infections was Pseudomonas aeruginosa.     

Acquisition of resistant microorganisms and infections in HIV-infected patients admitted to the ICU

Whether critically ill human immunodeficiency virus (HIV)-infected patients are at risk of acquiring nosocomial infections and resistant or potentially resistant microorganisms (RPRMs) remains to be clarified. The aim was to compare the acquisition of RPRMs, infections and mortality in critically ill HIV-infected and non-infected patients. An observational, prospective cohort study of patients admitted to a medical intensive care unit (ICU) was undertaken. Swabbing of nares, pharynx and rectum, and culture of respiratory secretions were obtained within 48 h of admission and thrice weekly thereafter. Clinical samples were obtained as deemed necessary by the attending physician. Clinical variables, severity scores on admission and exposures during ICU stay were collected. Logistic regression was used to evaluate ICU mortality. Out of the 969 included patients, 64 (6.6 %) were HIV-infected. These patients had a higher Acute Physiology and Chronic Health Evaluation (APACHE) II score on admission (19.5?±?6.6 vs. 21.1?±?5.4, p?=?0.02), stayed longer in the care unit and were more exposed to several invasive devices and antibiotics. There were no differences in the rate of acquisition of RPRMs and the only difference in ICU-acquired infections was a significantly higher incidence of catheter-related bacteraemia (3 % vs. 9 %, p?=?0.03). The ICU-related mortality was similar in both groups (14 % vs. 16 %, p?=?0.70) and in HIV-infected patients, it tended to be associated with a lower CD4 cell count (p?=?0.06). Despite a longer ICU stay, critically ill HIV-infected patients did not show a higher rate of RPRMs acquisition. The rate of ICU-acquired infection was similar between HIV-infected and non-infected patients, except for catheter-related bacteraemia, which was higher in the HIV-infected population. Mortality was similar in both groups.     

Pseudomonas aeruginosa: antibiotic susceptibility and genotypic characterization of strains isolated in the intensive care unit

A prospective study was carried out to assess the incidence and the local antibiotic susceptibility of Pseudomonas aeruginosa in intensive care units (ICUs) and to characterize cross-transmission by using pulsed-field gel electrophoresis as an epidemiologic tool. For this purpose, we screened surveillance cultures and routine clinical cultures from patients admitted to two adult ICUs during a 2-year period. Antibiotic susceptibility was determined by a disk diffusion method. The overall incidence of P. aeruginosa was 19.1 cases per 100 patients. Our findings concerning the antibiotic resistance of clinical isolates were concordant with those of other studies. Genotyping revealed that approximately 53.5% of P. aeruginosa colonization was acquired via cross-transmission; the other cases probably originated from endogenous sources. Cross-colonization seems to make a large contribution to the spread of P. aeruginosa in ICUs.     

Quinolone therapy in the management of infection after irradiation.

Ionizing radiation increases the recipient's susceptibility to local and systemic infection by endogenous and exogenous microorganisms. Most infections involve fatal Gram-negative septicemia, but those associated with trauma may be polymicrobial. The use of quinolone antimicrobial agents in the treatment of these infections in irradiated mice is reviewed. Quinolones were effective in controlling systemic endogenous Gram-negative infection following irradiation. Supplementation of quinolone therapy with penicillin prevented treatment failures due to Streptococci, and increased survival. Quinolones were found also to be effective in management of systemic exogenous infections due to orally ingested Klebsiella pneumoniae and Pseudomonas aeruginosa. A 21-day course of therapy of K. penumoniae infection was superior to a 7-day therapy. The effectiveness of quinolones in the management of these infections may be attributed to local inhibition of the offending organism's growth within the gut lumen, while preserving the anaerobic gut flora and their systemic antibacterial activity. Administration of agents effective against anaerobic bacteria may be required for the management of polymicrobial infections. Supplementing antianaerobic therapy with a quinolone can control the Gram-negative bacterial component of the infection and prevent Enterobacteriaceae translocation and mortality. The availability of an oral, as well as parenteral, route of administration, the advantage of achieving selective inhibition of potential pathogens in the gut, and the ability to treat systemic infection make the quinolones promising agents for the therapy of endogenous and exogenous infections after irradiation.     

Anaerobic bacteria commonly colonize the lower airways of intubated ICU patients

Objectives  To investigate respiratory tract colonization by aerobic and anaerobic bacteria in mechanically ventilated patients.
Methods  Bacterial colonization of the stomach and the respiratory tract was qualitatively and quantitatively analyzed over time in 41 consecutive mechanically ventilated patients in a Swedish intensive care unit (ICU), with special emphasis on elucidation of the role of anaerobic bacteria in the lower respiratory tract. Samples were taken from the oropharynx, gastric juice, subglottic space and trachea within 24 h (median 14 h) of intubation, and then every third day until day 18 and every fifth day until day 33.
Results  The patients were often heavily colonized with microorganisms not considered to belong to a healthy normal oropharyngeal and gastric flora on admission to the ICU. A majority harbored enterococci, coagulase-negative staphylococci and Candida spp. in at least one site on day 1. Anaerobic bacteria, mainly peptostreptococci and Prevotella spp., were isolated from subglottic and/or tracheal secretions in 59% of the patients. Different routes of tracheal colonization for different groups of microorganisms were found. Primary or concomitant colonization of the oropharynx with staphylococci, enterococci, enterobacteria and Candida was often seen, while Pseudomonas spp., other non-fermenting Gram-negative rods and several anaerobic species often primarily colonized the trachea, indicating exogenous or direct gastrointestinal routes of colonization.
Conclusions  Mechanically ventilated patients were heavily colonized in their lower airways by potential pathogenic microorganisms, including a high load of anaerobic bacteria. Different routes of colonization were shown for different species.     

The changing epidemiology of severe infections in the ICU

Data on the epidemiology of severe infection in the intensive care unit (ICU) can be used to monitor the effect of preventive measures and changes in policy or procedures. The most common risk factors associated with ICU-acquired infection include length of stay, antibiotic usage, catheterization and use of other invasive devices. The most frequent infections encountered in ICU patients include lower respiratory tract infections (especially pneumonia) and bacteremia, in addition to urinary tract infections and wound infections. Streptococcus pneumoniae, Haemophilus influenzae , methicillin susceptible Staphylococcus aureus and Enterobacteriaceae are most often implicated in community-acquired and early onset ICU-acquired infections, whereas late onset infection is more likely to be caused by pathogens which are more refractory to treatment, such as Enterobacter spp., Serratia spp., Pseudomonas aeruginosa, Acinetobacter spp. and methicillin-resistant S. aureus (MRSA). The pathogen spectrum also varies according to the site of infection, with Gram-positive bacteria being most frequently isolated in bacteremia and wound infections, whereas Gram-negative bacteria are prevalent in late-onset pneumonia and urinary tract infections. The prevalence of Gram-positive pathogens in bacteremia has increased over the past 20 years, mainly because of the increased isolation of coagulase-negative staphylococci (CNS) and enterococci. This is most probably due to the selective pressure exerted by the use of broad-spectrum antibiotics, such as the third-generation cephalosporins and fluoroquinolones, which are generally more potent against Gram-negative than Gram-positive bacteria, and to the increased use of invasive devices.
The increasing isolation frequency of Gram-positive pathogens in severe ICU infections has resulted in greater usage of vancomycin, which may account for the rising incidence of vancomycin-resistant enterococci.     

Epidemiology of carbapenem resistant Klebsiella pneumoniae colonization in an intensive care unit

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged during recent years in several intensive care units. The objective of our study was to determine the incidence of CRKP and the risk factors associated with acquisition during intensive care unit (ICU) stay. This prospective cohort study was conducted between May 2007 and April 2008 in a medical-surgical ICU at a tertiary medical center. Rectal surveillance cultures were obtained from patients on admission and twice weekly. Of screened patients, 7.0% (21/299) were CRKP colonized on admission to the ICU. One hundred eighty (81%) patients were screened at least twice. Of these, 48 (27%) patients acquired CRKP during ICU stay. Of the 69 CRKP colonized patients (both imported and ICU acquired), 29% (20/69) were first identified by microbiologic cultures, while screening cultures identified 49 patients (71%). Of these, 23 (47%) subsequently developed clinical microbiological cultures. Independent risk factors for CRKP acquisition included recent surgery (OR 7.74; CI 3.42-17.45) and SOFA score on admission (OR 1.17; CI 1-1.22). In conclusion, active surveillance cultures detected a sizable proportion of CRKP colonized patients that were not identified by clinical cultures. Recent surgical procedures and patient severity were independently associated with CRKP acquisition.