Nosocomial klebsiella infection in a neonatal unit: identification of risk factors for gastrointestinal colonization

Blueberry Phenolics Reduce Gastrointestinal Infection of Patients with Cerebral Venous Thrombosis by Improving Depressant-Induced Autoimmune Disorder via miR-155-Mediated Brain-Derived Neurotrophic Factor

Cerebral venous thrombosis (CVT) often causes human depression, whereas depression-induced low immunity makes the patients susceptible to gastrointestinal infection. Blueberry possesses antidepressant properties which may improve autoimmunity and reduce gastrointestinal infection. Brain-derived neurotrophic factor (BDNF) performs antidepressant function and can be regulated by miR-155, which may be affected by blueberry. To explore the possible molecular mechanism, blueberry compounds were analyzed by high-performance liquid chromatography. Activity of compounds was tested by using HT22 cells. The present study tested 124 patients with CVT-induced mild-to-moderate depressive symptoms (Center for Epidemiologic Studies—Depression Scale [CES-D] ≥16) and gastrointestinal infection. Patients were randomly assigned to blueberry extract group (BG, received 10 mg blueberry extract daily) and placebo group (PG, received 10 mg placebo daily). After 3 months, depression, gastrointestinal infection and lipid profiles were investigated. Serum miR-155 and BDNF were measured using real-time quantitative polymerase chain reaction and or Western Blot. Blueberry treatment improved depressive symptoms and lipid profiles, and also reduced gastrointestinal infection in the BG group (P < 0.05) but those of the PG group (P = 1). These changes were paralleled by increase in serum levels of BDNF and miR-155 (P < 0.05). HPLC analysis showed that blueberry extracts were the main phenolic acids with 0.18, 0.85, 0.26, 0.72, 0.66, 0.4,1, and 1.92 mg/g of gentisic acid, chlorogenic acid, [2]-epicatechin, p-coumaric acid, benzoic acid, p-anisic acid, and quercetin in blueberry extracts, respectively. Phenolics in blueberry are possible causal agents in improving antidepressant activity and reducing gastrointestinal infection. Administration of blueberry increased BDNF expression and miR-155. Blueberry cannot affect BDNF level when miR-155 is overexpressed or inhibited. Phenolics from blueberry reduced gastrointestinal infection of patients with CVT by improving antidepressant activity via upregulation of miR-155-mediated BDNF.

An Outbreak of Gentamicin-ResistantEnterobacter cloacaeInfections in a Pediatric Intensive Care Unit

The intensive care unit at Children's Medical Center in Dallas is a medical-surgical unit that cares for pediatric patients of all ages. In 1978 an outbreak of infections occurred that was caused by a gentamicin-resistant strain ofEnterobacter cloacae. Thirty of the 34 patients involved in the outbreak were neonates. Six patients developed bacteremia, five of them neonates. The neonates who became infected were significantly smaller (> 1500 g) and more premature (< 35 weeks) than control patients. Neonates with bacteremia had a significantly higher incidence of congenital anomalies. In a multi-specialty pediatric intensive care unit newborn infants were the group of patients at high risk for nosocomial infection.

Risk factors for nosocomial infections in selected neonatal intensive care units in Colombia, South America

OBJECTIVE

This study was designed to identify risk factors for nosocomial infections among infants admitted into eight neonatal intensive care units in Colombia. Knowledge of modifiable risk factors could be used to guide the design of interventions to prevent the problem.

STUDY DESIGN

Data were collected prospectively from eight neonatal units. Nosocomial infection was defined as culture-proven infection diagnosed after 72 hours of hospitalization, resulting in treatment with antibiotics for >3 days. Associations were expressed as odds ratios. Logistic regression was used to adjust for potential confounders.

RESULTS

From a total of 1504 eligible infants, 80 were treated for 127 episodes of nosocomial infection. Logistic regression analysis identified the combined exposure to postnatal steroids and H2-blockers, and use of oral gastric tubes for enteral nutrition as risk factors significantly associated with nosocomial infection.

CONCLUSION

Nosocomial infections in Colombian neonatal intensive care units were associated with modifiable risk factors including use of postnatal steroids and H2-blockers.

Molecular epidemiology of gram-negative bacilli from infected neonates and health care workers' hands in neonatal intensive care units

We sought to characterize the molecular epidemiology of gram-negative bacilli (GNB) causing infections in infants and associated with carriage on nurses' hands after hand hygiene was performed. From March 2001 to January 2003, GNB caused 192 (34%) of 562 hospital-acquired infections in the 2 participating neonatal intensive care units (NICUs) and were isolated from the hands of 45 (38%) of 119 nurses. Five species--Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens and Enterobacter cloacae, all of which were typed by pulsed-field gel electrophoresis--caused 169 (88%) of 192 of GNB infections. Overall, 58% of infections were caused by unique strains not cultured from other infants or nurses, and 31% of infections were part of unrecognized molecular clusters. In contrast, only 9% of strains that caused infections were cultured from nurses' hands. These data suggest that practices in addition to hand hygiene are needed to prevent horizontal transmission of GNB in the NICU.

Risk factors for hospital-acquired infections in the neonatal intensive care unit

Infants in the neonatal intensive care unit (NICU) have many risk factors for infection. Compared with older children and adults, infants, particularly premature infants, are relatively immunocompromised. Patients in the NICU have intrinsic risk factors for infections due to immunological "deficiencies" or inadequate development of mechanical barriers such as skin and gastrointestinal tract mucosa. Like other ICU populations, NICU patients have extrinsic risk factors for infection such as prolonged hospitalization, invasive procedures, instrumentation, medical treatments and concomitant medical conditions. Compared with healthy full-term infants, patients in the NICU develop abnormal flora, which is generally acquired in the NICU from patient-to-patient transmission via hand carriage of healthcare workers. This flora is frequently multidrug-resistant as it has developed under the selective pressure of antibiotics and can cause invasive disease. An understanding of the risk factors that are associated with hospital-acquired infections is essential to design preventive strategies.

A simultaneous outbreak on a neonatal unit of two strains of multiply antibiotic resistant Klebsiella pneumoniae controllable only by ward closure

Two aminoglycoside-resistant strains of Klebsiella pneumoniae caused an outbreak on the neonatal unit at St Thomas' Hospital. One, which affected 18 patients, was capsular type K18 and resistant to newer cephalosporins by the production of the extended-spectrum beta-lactamase SHV-2; the other, which colonized four patients, was capsular non-typeable and did not produce extended-spectrum beta-lactamase. Both strains were probably brought into the unit by carrier patients; the probable carrier of the non-typeable strain was transferred from another hospital but was negative on a single admission screen; the probable carrier of the K18 strain was not screened on admission because he had been born at St Thomas', but his mother had been transferred from another hospital. Despite intensive efforts to control the outbreak by standard methods of hand washing, screening, patient isolation and environmental cleaning, a total of 22 neonates on the unit eventually became colonized or infected. One of three patients with bacteraemia died. A small proportion of samples of expressed breast milk, electronic thermometers and oxygen saturation probes were contaminated by the K18 strain and may have contributed to some of the cross-infection, but this did not explain the extent of the outbreak. The outbreak was controlled only by opening a temporary ward for colonized neonates and another for newly born babies, which allowed the closure and cleaning of the main neonatal unit. Multiply antibiotic resistant klebsiellas may be highly epidemic and cause serious, difficult-to-control outbreaks on neonatal units. All patients, regardless of their admission history, should be screened on admission for carriage of multiply resistant enterobacteria by a sensitive method, and units should have plans for temporary ward closure should outbreaks occur.

Reduction in colonization and nosocomial infection by multiresistant bacteria in a neonatal unit after institution of educational measures and restriction in the use of cephalosporins

INTRODUCTION

Previous administration of third-generation cephalosporins predisposes to colonization and infections by multiresistant Enterobacter sp. The emergence of multiresistant bacteria infections in a neonatal unit during 1995, especially Enterobacter cloacae, stimulated this study.

OBJECTIVE

To evaluate the efficacy of measures to control colonization and nosocomial infection by multiresistant bacteria in a neonatal unit.

SETTING

A tertiary care university hospital.

PATIENTS AND METHODS

This study was conducted from October 1995 through December 1999 in 4 phases: a cross-sectional study, a longitudinal study with intervention measures, monthly cross-sectional studies, and determination of nosocomial infections caused by multiresistant bacteria (oxacillin-resistant Staphylococcus aureus and gram-negative bacteria resistant to either aminoglycosides or third-generation cephalosporins). Specimens for surveillance culture were obtained through umbilical and rectal swabs, and tracheal aspirates from intubated babies. The intervention measures were as follows: (1) appropriated training of the whole health care team, emphasizing measures to reduce cross-colonization, and the importance of rational usage of antibiotics and (2) suppression of usage of third-generation cephalosporins. Risk factors were analyzed through univariate and multivariate logistic regression.

RESULTS

In the first phase, 32% (10/31) of the patients were colonized by multiresistant bacteria (29% by multiresistant E cloacae ). In the second phase, 342 patients were evaluated; 33% of them were colonized by E cloacae, and a multiresistant strain was isolated in 10.8% (37/342) of the babies. A logistic regression model indicated parenteral nutrition and antibiotic usage as risk factors for colonization by multiresistant E cloacae. In the third phase, for 6 months, only 2 patients were colonized by multiresistant E cloacae. In the fourth phase, the analysis of bacterial resistance profile indicated a reduction of nosocomial infections due to multiresistant bacteria from 18 cases in 1995 to 2 cases per year until 1999.

CONCLUSION

These results have shown that the measures adopted were effective.

An antibiotic policy to prevent emergence of resistant bacilli

BACKGROUND

Fear of infection in neonatal intensive care units (NICUs) often leads to early use of empiric broad-spectrum antibiotics, a strategy that selects for resistant bacteria. We investigated whether the emergence of resistant strains could be halted by modifying the empiric antibiotic regimens to remove the selective pressure that favours resistant bacteria.

METHODS

Two identical NICUs were assigned to different empiric antibiotic regimens. On unit A, penicillin G and tobramycin were used for early-onset septicaemia, flucloxacillin and tobramycin were used for late-onset septicaemia, and no broad-spectrum beta-lactam antibiotics, such as amoxicillin and cefotaxime were used. In unit B, intravenous amoxicillin with cefotaxime was the empiric therapy. After 6 months of the study the units exchanged regimens. Rectal and respiratory cultures were taken on a weekly basis.

FINDINGS

There were 436 admissions, divided equally between the two regimens (218 in each). Three neonates treated with the penicillin-tobramycin regimen became colonised with bacilli resistant to the empirical therapy used versus 41 neonates on the amoxicillin-cefotaxime regimen (p<.0001). The relative risk for colonisation with strains resistant to the empirical therapy per 1000 patient days at risk was 18 times higher for the amoxicillin-cefotaxime regimen compared with the penicillin-tobramycin regimen (95% CI 5.6-58.0). Enterobacter cloacae was the predominant bacillus in neonates on the amoxicillin-cefotaxime regimen, whereas Escherichia coli predominated in neonates on the penicillin-tobramycin regimen. These colonisation patterns were also seen when the units exchanged regimens.

INTERPRETATION

Policies regarding the empiric use of antibiotics do matter in the control of antimicrobial resistance. A regimen avoiding amoxicillin and cefotaxime restricts the resistance problem.

Risk factors for nosocomial sepsis in newborn intensive and intermediate care units

A multicentre prospective study was performed to estimate the incidence of hospital infections and to identify the most relevant risk factors for sepsis in a large and unselected population of high-risk newborns. The study involved 49 neonatal intensive care units and 17 neonatal intermediate care units in Italy. Newborns were followed up from admittance to the units until discharge. Data on demographics and clinical characteristics, exposure to the principal invasive procedures, and onset of infectious complications were prospectively collected. Only infections developing after 48 h from admittance to the unit were recorded. A multiple logistic regression was performed to identify which factors were independently associated with sepsis. Among the 8263 newborns included in the analysis, the incidence of infected newborns was 14.4 per 100 newborns and 0.9/100 days of stay. The incidence of infections was 19.1/100 newborns and 1.2/100 days of stay. Sepsis represented 15.4% of all infections (incidence 2.9/100 newborns and 0.2/100 days of stay). The following factors were independently associated with sepsis: umbilical catheterization, both through the vein and the artery for more than 5 days; mechanical ventilation for more than 5 days; necrotizing enterocolitis; birth weight equal to or less than 2500 g; nasogastric tube; total parenteral nutrition; and transfer from other hospitals. Umbilical catheters accounted for the highest proportion of sepsis (62%), followed by arterial catheters (31%), nasopharyngeal cannulae (26%), tracheal cannulae (20%), and nasal cannulae (20%). The population attributable risk for the other procedures was less than 10%.

CONCLUSION

This study demonstrates that in a large and unselected newborn population, several host factors and invasive procedures are independently associated with an increased risk of sepsis. After adjustment for clinical severity, intravascular catheterization and assisted ventilation were found to be responsible for a considerable proportion of observed sepsis. They should therefore be considered as priorities for interventions, aimed both at reducing unnecessary use and promoting more strict compliance with aseptic practices.

Epidemic gram-negative bacteremia in a neonatal intensive care unit in Guatemala

BACKGROUND

Nosocomial bloodstream infection is an important cause of morbidity and mortality among neonates. From September 1 through December 5, 1990 (epidemic period), gram-negative bacteremia developed in 26 neonates after their admission to the neonatal intensive care unit (NICU) of Hospital General, a 1000-bed public teaching hospital in Guatemala with a 16-bed NICU. Twenty-three of the 26 patients (88%) died.

METHODS

To determine risk factors for and modes of transmission of gram-negative bacteremia in the NICU, we conducted a cohort study of NICU patients who had at least one blood culture drawn at least 24 hours after admission to the NICU and performed a microbiologic investigation in the NICU.

RESULTS

The rate of gram-negative bacteremia was significantly higher among patients born at Hospital General, delivered by cesarian section, and exposed to selected intravenous medications and invasive procedures in the NICU during the 3 days before the referent blood culture was obtained. During the epidemic period, the hospital's chlorinated well-water system malfunctioned; chlorine levels were undetectable and tap water samples contained elevated microbial levels, including total and fecal coliform bacteria. Serratia marcescens was identified in 81% of case-patient blood cultures (13/16) available for testing and from 57% of NICU personnel handwashings (4/7). Most S. marcescens blood isolates were serotype O3:H12 (46%) or O14:H12 (31%) and were resistant to ampicillin (100%) and gentamicin (77%), the antimicrobials used routinely in the NICU.

CONCLUSIONS

We hypothesize that gram-negative bacteremia occurred after invasive procedures were performed on neonates whose skin became colonized through bathing or from hands of NICU personnel.

Spread of Klebsiella in a neonatal ward

The colonization of infants with Klebsiella pneumoniae was prospectively studied. Samples were taken from nose, throat, umbilicus and rectum on the day of arrival and thereafter once a week. Phage typing was performed the first time K. pneumoniae was found at any of these sites. Settle plates were exposed in the incubators and in the patient rooms 5 h/day. The study lasted for 32 weeks. The first 15 weeks was a control period with no information to the staff, the following 4 weeks was a period of intervention and education and the last 13 weeks was a second control period. In all, 603 infants were investigated. The number of infants nursed per week and severity of their disease was comparable in the 3 periods. The colonization rates were 65, 34 and 58%, respectively. The acquisition of new strains was 1.4 per infant in the first and last periods, but only 0.4 in the period of intervention. Thus, colonization rates decreased only during the period of continuous education in hygiene.

Nosocomial infection in neonatal intensive care units

Nosocomial infection rates in neonatal intensive care units range from 5% to 25%. Both endemic and epidemic infections have been documented, with causative agents including gram-positive cocci, gram-negative bacilli, and viruses. This paper reviews the host, maternal, and environmental factors that influence susceptibility of neonates. Usual preventive measures, such as nursery design, staff apparel, handwashing, employee health, and neonatal care, as well as epidemic control measures to minimize infection risks and limit transmission of infectious organisms, are discussed.

The bacterial flora of neonates in intensive care-monitoring and manipulation

Unlike healthy babies, newborns hospitalized in the neonatal intensive care unit (NICU) are colonized with bacterial flora that reflects their exposure to pathogens in the NICU, not bacterial acquired from mother in the perinatal period. For example, nosocomial Gram-negative bacilli, such as klebsiella, enterobacter, and citrobacter but not Escherichia coli tend to colonize the gastrointestinal tract. Colonization with Gram-negative bacilli generally is a prerequisite for nosocomial infection with these pathogens, but surveillance cultures may not be a cost effective approach to predicting which babies will ultimately become ill. However, screening cultures to detect the emergence of antibiotic-resistant Gram-negative bacilli facilitate containment and guide empiric antibiotic therapy, and surveillance cultures are necessary to detect colonized babies when nosocomial Gram-negative bacilli become epidemic in the NICU. Such cultures are inexpensive and easy to perform if appropriate selective media are used. Surveillance cultures to detect coagulase-negative staphylococci, which numerous investigators claim are increasingly important NICU pathogens, are of little value since colonization is virtually universal in the first week of life. Documentation of colonization with group B streptococci or Staphylococcus aureus also cannot be justified on a routine basis. Screening for methicillin-resistant S. aureus, however, may be indicated since early detection of these strains can limit dissemination in the NICU. Research aimed at restoring colonization resistance with elements of normal bacterial flora or preventing colonization by nosocomial pathogens is in its infancy.

The epidemiology of nosocomial infections caused by Klebsiella pneumoniae

Klebsiella pneumoniae causes serious epidemic and endemic nosocomial infections. We conducted a literature review to characterize the epidemiology of epidemic K. pneumoniae outbreaks. Eighty percent of the outbreaks (20/25) involved infections of the bloodstream or urinary tract. Person-to-person spread was the most common mode of transmission, and nearly 50% of the outbreaks occurred in neonatal intensive care units. No one serotype predominated, and no association was found between serotype and either the site of infection or antimicrobial susceptibility pattern. We used data reported to the Centers for Disease Control (CDC) by hospitals participating in the National Nosocomial Infections Study (NNIS) to describe the epidemiology of endemic K. pneumoniae infections. In the 8-year period from 1975 through 1982 the nosocomial K. pneumoniae infection rate was 16.7 infections per 10,000 patients discharged. The rate of infection at medical school-affiliated hospitals was significantly greater than at nonaffiliated hospitals; furthermore, the rate of infection at large affiliated hospitals was greater than at small affiliated hospitals. The rate of infection varied by service, with the highest rate found on the medicine service. During the 8-year period, 184 deaths were caused by nosocomial K. pneumoniae infections (184 deaths/16,969 infections, case-fatality ratio 1.1%), with higher ratios in pediatrics (5%) where there was a 12% mortality in children infected with an aminoglycoside-resistant strain.

Effect of an expanded physical facility on nosocomial infections in a neonatal intensive care unit

Fifty-two months' data were reviewed to assess the effect of a threefold increase in space per infant in a neonatal intensive care unit on rates of nosocomial infections (NIs) and colonization with Staphylococcus aureus (39 months in a crowded 18-bed unit and 13 months in a spacious 32-bed unit). Mean length of stay, survival rates, mean birth weights, and other parameters indicated that infant populations in the old and new units were similar. NI rates were not significantly different in the old and new units (11.7% and 9.6%, respectively; p = 0.17) nor were rates of colonization of anterior nares with S. aureus (11.7% and 10.7%; p = 0.5). NI rates, but not S. aureus colonization rates, were significantly higher during months of high patient turnover (p less than 0.01). Sites of infection were similar in the old and new units. There was, however, a significant change in bacterial species causing NI. Klebsiella pneumoniae and Pseudomonas aeruginosa caused 20.4% of NIs in the old unit, but only 2.1% in the new unit (p less than 0.001) and NIs caused by S. epidermidis increased from 4.7% to 14.9% (p = 0.02) in the new unit. There was also a marked decrease in the numbers of clusters of NI occurring in the new unit, indicating that cross-infections between infants were probably minimized.

Streptococcus faecium outbreak in a neonatal intensive care unit

An outbreak of bacteremia and meningitis in a neonatal intensive care unit is described. Seven cases occurred in premature infants with severe underlying diseases. An epidemiological investigation failed to document the reservoir of the epidemic strain but suggested that its transmission among the infants was via the hands of hospital personnel. All patients had nasogastric tubes and multiple intravascular devices, and the portal of entry may have been either the gastrointestinal tract or the sites of the intravascular devices. Conventional biotyping of isolates failed to differentiate between isolates from infected patients and isolates recovered from prevalence surveys and from the environment. However, rapid identification systems (API-20S [Analytab Products, Plainview, N.Y.] and the AutoMicrobic system [Vitek Systems, Inc., Hazelwood, Mo.]) were able to distinguish isolates recovered from infected patients and hands of hospital personnel from isolates recovered during prevalence and environmental surveys and 29 isolates from widespread geographical areas. This is the first known report of a nosocomial neonatal outbreak of bacteremia and meningitis due to Streptococcus faecium; it underscores the importance of identifying streptococci to species level.

An outbreak of gentamicin-resistant Klebsiella pneumoniae: analysis of control measures

In April 1978, a strain of gentamicin-resistant Klebsiella pneumoniae (GRK) was introduced into the neonatal intensive care unit of Henry Ford Hospital. An additional ten cases of GRK occurred over the subsequent 16 months and intestinal colonization occurred in up to 91% of admissions per month. All GRK were susceptible to amikacin and were capsular serotype 19. Though hand contamination of hospital personnel with GRK was documented, increased handwashing practices did not reduce colonization rates of neonates with the epidemic strain. Intestinal carriage persisted for up to ten months and could not be eradicated by administering oral colistin sulfate. Discontinuation of gentamicin and utilization of amikacin were associated with a significant reduction in colonization with GRK (p less than 0.05). However, the only control measure that prevented both new cases and colonization with the epidemic strain was the utilization of a strict cohort system.

Epidemic Serratia marcescens in a neonatal intensive care unit: importance of the gastrointestinal tract as a reservoir

Between a March and December of 1979, and outbreak of infections due to multiply antibiotic resistant Serratia marcescens took place in a 50-bed neonatal intensive care unit. Fifteen neonates suffered major infections (sepsis, meningitis and pneumonia) with one death, and 20 suffered minor infections (conjunctivitis, cystitis, wound infections). Epidemiologic investigation failed to reveal a common source; S. marcescens, however, ws isolated from an employee's hand, emollient skin cleanser, suction tubing, and three in-use manual infant resuscitation bags. The skin cleanser and equipment-cleaning agents were ineffective against S. marcescens. Asymptomatic, colonized infants were the major reservoir of S marcescens. These infants were identified by daily cultures of the nose, umbilicus and rectum. The rectal swab most commonly (76%) yielded first-positive cultures in previously uncolonized infants, and was ultimately positive in 92% of colonized infants. A control program was begun by: 1) removing all inanimate sources of S. marcescens; and 2) cohorting patients and staff into a S. marcescens-exposed group and a new patient group. The new patient group of infants was surveyed by daily triple-site cultures for colonization and subsequent transfer to the S. marcescens-exposed group. After four months, the epidemic was controlled and the organism eradicated from the neonatal intensive care unit.

Nursery epidemic due to multiply-resistant Klebsiella pneumoniae: epidemiologic setting and impact on perinatal health care delivery

Gram-negative bacilli frequently cause epidemics in high-risk newborn intensive care units. Recently, an epidemic caused by a multiply-resistant K. pneumoniae, serotype 21, occurred in the Vanderbilt University intensive care nursery. The background of this outbreak included an increasing endemic nosocomial sepsis rate, operation of the facility in excess of rated capacity, and increasingly inadequate nurse-to-patient staffing ratios. The epidemic lasted 11 weeks; 26 (12%) of the 232 infants at risk in the unit became colonized. Five infants developed systemic illness and one died. Cohorting, reinforcement of strict handwashing and isolation procedures, and closure of the unit to outborn admissions resulted in rapid termination of the outbreak. Followup studies performed on infants colonized with the epidemic bacterium demonstrated persistent fecal shedding up to 13 months following discharge from the hospital. This epidemic had a detrimental influence on high-risk newborn and obstetric health care delivery in an area encompassing portions of three states. Under a system of progressively more sophisticated referral units, nosocomial infections occurring at a tertiary center can have an impact on other hospitals within the network.