Prevention of bacterial infection and sepsis in acute severe pancreatitis.

Between 1984 and 1986 six patients with acute respiratory failure (requiring ventilation for at least 3 days) complicating acute pancreatitis were managed on the intensive care unit (median ventilation period 6 days; range 3-41 days). Between 1987 and 1989 nine similar patients were managed (median ventilation period 35 days, range 4-69 days), and a regimen of enteral tobramycin, polymyxin and amphotericin to selectively decontaminate the digestive tract (SDD) was introduced. Five of six patients treated before 1987 had serious infections (three Gram-negative, one fungal), compared with only one of nine patients treated with SDD (P < 0.05). Clinical signs of sepsis were evident for 62% of the pre-SDD period, compared with 39% of the period during SDD therapy (P < 0.001). Systemic antibiotic prescribing was reduced in the SDD group; however, mortality remained unaffected with only two patients surviving pre-SDD and three during SDD treatment. SDD reduces infection rates and sepsis in patients with acute pancreatitis and may help to improve the prognosis of this life-threatening condition.     

Methicillin-resistant Staphylococcus aureus in children with cystic fibrosis: An eradication protocol

A retrospective 12-year study (May 1988-July 2000) was undertaken in children with cystic fibrosis (CF) to evaluate 1) the magnitude of methicillin-resistant Staphylococcus aureus (MRSA) in these children; 2) the clinical impact of MRSA on CF; and 3) the efficacy of an MRSA protocol aimed at the eradication of the carrier state. The study maneuver comprised of 1) surveillance cultures of throat/rectum to detect the MRSA carrier state; 2) life-long cephradine rather than flucloxacillin to lift selection pressure; 3) topical application of oral and nebulized vancomycin for 5 days to clear the carriage of MRSA; and 4) a strict antistaphylococcal hygiene program, including handwashing and device policy. Fifteen children with CF (11 boys, with median age 117 months) positive for MRSA were enrolled. The current prevalence of MRSA among children with CF in our hospital is 6.5%. Of 15 children identified, only 12 (18 episodes of MRSA colonization) were treated according to protocol. Median age of MRSA acquisition was 73 months (interquartile range, 43-134 months). In 7 patients (55%), MRSA was eradicated. Of a total of 18 MRSA episodes, the protocol was successful in 10 episodes. The mean period of MRSA-free status was 12 months (range, 6-36 months). Pulmonary function (measured by FEV(1)) was not affected (68% of predicted before treatment, and 68% of predicted after treatment). All children were oropharyngeal carriers of both MRSA and ceftazidime-resistant P. aeruginosa. We believe that an effort has to be made to limit MRSA in CF clinics for the following reasons: 1) MRSA carriage in any individual is an abnormal condition; 2) limitation of systemic vancomycin use is desirable; 3) MRSA carriage may be a contraindication for lung transplantation; and 4) epidemiologically, a CF unit with a substantial MRSA problem functions as a source of dissemination for other patients.     

Oropharyngeal carriage and lower airway colonisation/infection in 45 tracheotomised children

BACKGROUND: A study was undertaken to determine the oropharyngeal carrier state of potentially pathogenic microorganisms (PPM) and the magnitude of colonisation and infection rates of the lower airways with these PPM in children requiring long term ventilation first transtracheally and afterwards via a tracheotomy. METHODS: A 5 year, prospective, observational cohort study was undertaken in 45 children (33 boys) of median age 6.4 months (range 0-180) over a 5 year period at the Royal Liverpool Children's NHS Trust of Alder Hey, a university affiliated tertiary referral centre. The children were first admitted to the 20-bed paediatric intensive care unit (PICU) and, following placement of a tracheotomy, they were transferred to a four bedded respiratory ward. The two main indications were neurological disorders and airway obstruction. All children were ventilated transtracheally for a median period of 12 days (range 0-103) and, after placement of the tracheotomy, for a similar period of 12 days (range 1-281). Surveillance cultures of the oropharynx were taken on admission to the PICU and on the day of placement of the tracheotomy. Throat swabs were taken twice weekly during ventilation, both transtracheal and via the tracheotomy. Tracheal aspirates were taken once weekly and when clinically indicated (in cases where the lower airway secretions were turbid). RESULTS: Twenty five patients (55%) had abnormal flora, mainly aerobic Gram negative bacilli (AGNB), particularly Pseudomonas aeruginosa, while the community PPM Staphylococcus aureus was present in the oropharynx of 37% (17/45) of the study population. The lower airways were sterile in six children; the other 39 patients (87%) had a total of 82 episodes of colonisation. "Community" PPM significantly increased once the patients received a tracheotomy, independent of the number of patients enrolled, episodes of colonisation/infection, and the number of colonised/infected patients. "Hospital" PPM significantly decreased after tracheotomy only when episodes were compared. CONCLUSIONS: While P aeruginosa present in the admission flora caused primary endogenous colonisation/infection during mechanical ventilation on the PICU, S aureus not carried in the throat was responsible for the exogenous colonisation/infection once the patients had a tracheotomy. This is in sharp contrast to adult studies where exogenous infections are invariably caused by AGNB. This discrepancy may be explained by chronic underlying conditions such as diabetes, alcoholism, and chronic obstructive pulmonary disease which promote AGNB, whereas the children were recovering following tracheotomy.     

The effects of intravenous epidermal growth factor on bacterial translocation and central venous catheter infection in the rat total parenteral nutrition model

 Sepsis is a major complication of total parenteral nutrition (TPN) in children. Gut mucosal atrophy (GMA) and bacterial translocation (BT) occur in patients receiving TPN, and the translocated enteric organisms may cause central venous catheter (CVC) infection. Epidermal growth factor (EGF) has a trophic effect on the gut mucosa and may reduce BT, thereby reducing catheter infection. Using a rat TPN model, the relationship between GMA, BT, and catheter sepsis was examined and the effect on these of intravenous EGF was studied. There were four experimental groups. Group 1 had no CVC, Groups 2, 3, and 4 had a continuous central venous infusion as follows: group 2, saline; group 3, TPN; group 4, TPN with EGF. Groups 1 and 2 had free access to chow, groups 3 and 4 had no enteral feeds. After killing at 1 week, blood, tissue, and catheter specimens were cultured and mucosal morphology analysed. BT was defined as the presence of the same organism in cultures from the gut lumen and mesenteric lymph nodes (MLN). TPN only (group 3) resulted in GMA and BT, and 5 of 12 animals with BT had the same gut bacteria in blood and/or catheter cultures. The addition of EGF to the TPN significantly reduced GMA, BT to the MLN, and blood and/or catheter infections (P =< 0.05). In animals carrying enterococci, there was a significant reduction in translocation of enterococci (group 3: 8/14; group 4: 0/11; P < 0.05) and catheter infection by enterococci was prevented (group 3: 3/14; group 4: 0/11). EGF thus reduced GMA, BT, and blood and/or catheter infection when given IV to rats receiving TPN. Enterococcal translocation and subsequent blood and/or catheter infection was completely prevented, suggesting a selective effect of EGF. Accepted: 13 December 1999     

Control of imported and acquired methicillin-resistant Staphylococcus aureus (MRSA) in mechanically ventilated patients: a dose-response study of enteral vancomycin to reduce absolute carriage and infection

This study aimed to quantify the animate source provided by the patients using the concept of "absolute carriage" by multiplying the carrier rate by the level of carriage; and to compare the impact of a low and high dose of an oropharyngeal vancomycin gel on the absolute MRSA carriage and infection. In all, 265 patients were included, 126 were MRSA positive. Fifty-five patients received 2% vancomycin gel during the first year whilst 4% vancomycin gel was given to 50 patients during the second year. Surveillance swabs of throat and rectum were obtained from all eligible patients on admission and then twice weekly. The vancomycin protocol was started as soon as the surveillance cultures were positive for MRSA. Those patients received one gram of enteral vancomycin daily, divided into four doses. During the first year 2% vancomycin gel 4 ml (80 mg) was applied in the oropharynx in four doses in addition to the enteral solution (Group A). During the second year 4% vancomycin gel 4 ml (160 mg) was used (Group B). The absolute carriage was high during both periods: 3.6 for Group A, and 3.2 for Group B. The 4% vancomycin protocol significantly reduced the absolute carriage, compared to the 2% vancomycin protocol: 2.6 versus 1.5 (P < 0.01). Significant reduction in secondary endogenous infections was found in the second year: seven versus 15 patients (P < 0.05). A total of 3,588 microbiological samples were processed. Neither Staphylococcus aureus with intermediate sensitivity to vancomycin (VISA) nor vancomycin-resistant enterococci (VRE) were detected.     

Handwashing in the intensive care unit: a big measure with modest effects

Handwashing is widely accepted as the cornerstone of infection control in the intensive care unit. Nosocomial infections are frequently viewed as an indicator of poor compliance of handwashing. The aim of this review is to evaluate the effectiveness of handwashing on infection rates in the intensive care unit, and to analyse the failure of handwashing. A literature search identified nine studies that evaluated the impact of handwashing or hand hygiene on infection rates, and demonstrated a low level of evidence for the efforts to control infection with handwashing. Poor compliance cannot be blamed as the only reason for the failure of handwashing to control infection. Handwashing on its own does not abolish, but only reduces transmission, as it is dependent on the bacterial load on the hand of healthcare workers. Finally, recent studies, using surveillance cultures of throat and rectum, have shown that, under ideal circumstances, handwashing can only influence 40% of all intensive care unit infections. A randomised clinical trial with the intensive care as randomisation unit is required to support handwashing as the cornerstone of infection control.     

RSV outbreak in a paediatric intensive care unit

The Royal Liverpool Children's Hospital-Alder Hey paediatric intensive care unit (PICU) usually has a low rate of nosocomial respiratory syncytial virus (RSV) infection. We report and analyse a major outbreak of nosocomial (acquired) RSV infection on the PICU during a RSV season. All children admitted to the PICU were studied during the six-month winter period 1 October 2002 to 31 March 2002. Nasopharyngeal aspirates were tested using an in vitro enzyme-linked immunoassay (ELISA) membrane test for RSV antigen. PICU-acquired RSV infection was considered to have occurred when a child admitted to the PICU was RSV negative, or from whom no samples were taken as they did not exhibit signs of bronchiolitis, but was RSV positive five or more days after the admission. Fifty-four patients tested RSV positive using the ELISA on the PICU. All the patients were ventilated. Thirty-nine children were RSV positive using the ELISA on admission to the PICU ('imported' cases) and 15 became RSV positive whilst on the PICU ('acquired' cases). The source of the acquired RSV infection accounting for the first peak/outbreak in nosocomial cases were RSV-positive children in isolation cubicles. Acquired cases of RSV infection subsided with reinforcement of traditional methods of barrier precautions. The source of the second peak in nosocomial cases were persistent shedders of RSV. Seventy-three percent (11/15) of the acquired RSV cases had one or more of the following co-morbidities: congenital heart disease, chronic lung disease, airways abnormalities or immunosuppression. Droplet precautions (strict handwashing, use of gloves if handling body fluids, single-use aprons, education) rather than the physical barrier of the cubicle itself played a more important role in curtailing nosocomial spread. Persistent shedders of RSV are an important potential source of nosocomial RSV infection within a PICU. Patients with co-morbidities are at increased risk of nosocomial RSV infection.     

Long-term prophylaxis of infection by selective decontamination in leukopenia and in mechanical ventilation

The autochthonous anaerobic bacterial flora in the mucosal layer of the gastrointestinal tract limits colonization by aerobic potential pathogens. This effect is called colonization resistance. Colonization of the digestive tract by potentially pathogenic microorganisms precedes infection in patients with leukopenia and in cases of mechanical ventilation and can be prevented by long-term administration of antimicrobial agents that spare the autochthonous anaerobic bacterial flora of the mucous membranes, a concept known as selective decontamination. Antimicrobial agents active against anaerobic flora reduce colonization resistance, permitting colonization by and overgrowth of potentially pathogenic microorganisms and possibly leading to infections with resistant microorganisms. A distinction can be made between antimicrobial agents that reduce colonization resistance and those that leave it intact by examining the effect of antimicrobial agents on aerobic intestinal flora of mice and humans.