Nosocomial infections in the neonatal intensive care unit

Expression of superantigens and the agr system in Staphylococcus epidermidis

Infections with coagulase-negative staphylococci (CoNS) can involve the production of toxins such as superantigens, which contribute to tissue degradation and inflammatory immune responses. The accessory gene regulator (agr) quorum sensing system coordinates the expression of most S. aureus virulence factors. Therefore, the aim of this study was to investigate the expression of these superantigens and the presence of the agr locus in CoNS strains isolated from blood cultures. PCR was used to detect enterotoxin and agr genes and expression was analyzed by RT-PCR. Expression of the sea gene was observed in one S. epidermidis isolate andof sec-1 in two, seg and sei were expressed concomitantly in one isolate, and sei was expressed in another isolate. The agr group I was detected in S. epidermidis expressing the sea, seg and sei genes, whereas agr group II was detected in isolates expressing thesec-1 gene. The agr groups were only expressed in strains expressing thesec-1 gene. The results show that enterotoxin genes are highly frequent in CoNS isolated from clinical specimens and confirm the toxin-producing ability of these strains. The agr group II may be associated with enterotoxin C production by S. epidermidis, increasing the virulence of strains isolated from blood cultures and consequently the severity of sepsis caused by these organisms.

Infections in a Children's Hospital autopsy population

We reviewed our Children's Hospital autopsies (1986-2009, 3-8 year groups) to determine the contribution of infections/inflammation to death and trends over time. Infections were categorized as (1) underlying cause of death, (2) mechanism of death complicating another underlying cause of death, (3) contributing (4) agonal or (5) incidental. Of 608 autopsies (44% of deaths), 401 had 691 infections (66%, 1.72 infections/infected child). In categories 1-5, there were 85 (12.3%), 237(34.3%), 231 (33.4%), 82 (11.9%) and 56(8.1%) infections. Leading infections include bronchopneumonia (188), sepsis (144- Enterococcus most common with 22), meningitis (35- Streptococcus pneumoniae most common with 10), pneumonitis (33), peritonitis (29). Sepsis declined in 2002-2009, attributed to fluid resuscitation standardization. Meningitis declined after 1993, and may be partially attributed to vaccines (Hemophilus influenza, Streptococcus pneumoniae). Despite advances in anti-microbial therapy, 66% of pediatric autopsies had inflammatory lesions, predominately as the mechanism or contributing factor rather than the underlying cause of death.

Bloodstream infections and antimicrobial resistance patterns in a South African neonatal intensive care unit

BACKGROUND

Bloodstream infections remain a leading cause of morbidity and mortality in neonatal intensive care units (NICU) worldwide. Commonly isolated NICU pathogens are increasingly resistant to standard antimicrobial treatment regimes.

OBJECTIVES

The primary aim of this study was to determine the burden of bloodstream infections (BSI) in an NICU in a low-to-middle-income country and to describe the spectrum of pathogens isolated together with their drug susceptibility patterns.

METHODS

This retrospective, descriptive study included NICU patients admitted to the Tygerberg Children's Hospital, Cape Town, between 1 January and 31 December 2008. All blood culture samples submitted to the reference laboratory were extracted and clinical data on patients were obtained by hospital record review.

RESULTS

There were 78 culture-confirmed episodes of BSI in 54/503 (11%) patients admitted; median gestational age was 31 weeks (IQR 29-37) and birth weight 1370 g (IQR 1040-2320). Common isolates included coagulase-negative Staphylococcus (22/78, 28%), Klebsiella spp. (17/78, 22%), Acinetobacter spp. (14/78, 18%), Candida spp. (9/78, 11·5%) and methicillin-resistant Staphylococcus aureus (5/78, 6%). There was a predominance of gram-negative organisms (38/78, 48·7%). All Staphylococcus aureus isolates were methicillin-resistant and 59% of Klebsiella pneumoniae isolates were extended spectrum β-lactamase (ESBL) producers. Acinetobacter baumanii isolates showed low susceptibility to the aminoglycosides, carbapenems and cephalosporins. Of 54 infants admitted to the NICU with BSI, 25 (46%) died; 9/25 deaths (36%) were attributable solely to infection.

CONCLUSION

Compared with overall mortality in the NICU, that attributable solely or partly to BSI was high. Many bacterial BSI isolates were resistant to current empiric antibiotic regimens. Regular microbiological and clinical surveillance of BSI in NICUs is required to inform appropriate antibiotic protocols and monitor the impact of infection prevention strategies.

Pichia fabianii blood infection in a premature infant in China: case report

Background

Invasive fungal infections caused by uncommon fungi have increased in recent years. Hospitalized low-birth-weight infants are at high risk for neonatal fungal infections. Pichia fabianii is a rare pathogen causing blood infection, which has reportedly caused only 4 cases of fungemia and 1 case of endocarditis worldwide. Here, we describe the first case of a P. fabianii blood infection in a premature infant in China.

Case presentation

On July 28^th, a low-birth-weight (LBW, 1760 g) female infant born at 33⁺⁴ weeks of gestation was admitted to the pediatric intensive care unit with mild neonatal asphyxia. Until August 2^nd, a mechanical respirator was used to assist respiration under the Continuous Positive Airway Pressure (CPAP) model. The baby had an increased body temperature and a fever. To prevent infection, Ceftriaxone Sodium (CS) was administered intravenously for three days, after which Cefepime was administered until August 13^th. Chest X-rays showed suspected plaque-like shadows in the right lung. Blood cultures twice tested positive for fungal infection caused by Candida pelliculosa (recognized as Pichia fabianii later), which is first mis-identified by commercial kit. Hence, intravenous fluconazole was administered. However, cultures of other body fluids (e.g., urine, feces and sputum) tested negative for fungal infection. Routine tests and biochemistry of cerebrospinal fluid (CSF) were normal. Latex agglutination of Cryptococcus neoformans and fungi cultures in the CSF were also negative. After 14 days of intravenous fluconazole, blood was re-cultured, the result of which was negative. On August 30^th, intravenous fluconazole was suspended. On Sep 3^rd, the infant left the hospital in good health.

Conclusions

This is the first case of a blood infection caused by P. fabianii in a LBW premature female infant in China. Risk factors for fungal infection include premature birth, as well as mechanical invasive operation and antibacterial drug usage. Whether such risk factors necessitate prophylactic use of antifungal drugs is an important question that has yet to be fully addressed. Additionally, the pathogen P. fabianii collected in this study was resistant to amphotericin B (AMB) and itraconazole (ITR). With the exception of the azole-resistant endocarditis case, all other cases have not demonstrated such a resistance. Finally, commercial biochemical methods used in routine practice are limited in their ability to identify P. fabianii. Molecular genetic based methods are imperative for identification of uncommon fungal species from disseminated infections.

Outcomes of neonatal candidiasis: the impact of delayed initiation of antifungal therapy

Objective/Methods. To determine the outcomes of invasive neonatal candidiasis before institution of routine antifungal prophylaxis, we conducted a retrospective review of cases of invasive candidiasis in newborns in a referral-based neonatal intensive care unit located in a single tertiary academic center between January 1998 and December 2002. Results. Sixty-three newborns with invasive neonatal candidiasis were identified. Overall mortality rate was 35%. Virtually every infant had a central venous catheter (CVC), required mechanical ventilation and previous administration of antibacterial agents. Delayed institution of antifungal therapy was associated with increased mortality. In addition, length of hospitalization, duration of prior antibacterial therapy, mechanical ventilation, and CVC use, as well as evidence of end-organ disease, were associated with an adverse outcome. Conclusions. Reliance on available laboratory tools in cases of invasive neonatal candidiasis can result in delayed diagnosis and increased mortality. A risk-factor-based approach to empirical treatment could be justified in this setting.

Avaliação do diagnóstico da sepse neonatal: uso de parâmetros laboratoriais e clínicos como fatores diagnósticos

Objetivou-se descrever e comparar as características clínicas, laboratoriais e assistenciais de RN que apresentaram sepse comprovada tardia e de RN que apresentaram sepse não comprovada tardia. Em seguida, avaliar se houve diferença entre os grupos, além de descrever os germes prevalentes na unidade neonatal estudada. Estudo descritivo, envolvendo 168 casos. Observou-se que 33,3% tiveram sepse tardia provada. A idade no momento da sepse, o tempo total de internação, a quantidade total de neutrófilos, a quantidade de neutrófilos imaturos e o valor da PC-r mostraram bons parâmetros na diferenciação entre os dois grupos quando analisados de forma isolada. A Klebisiella pneumoniae, o Staphylococcus coagulase negativo e o S. aureus foram as bactérias mais comumente isoladas.

[Prevalence of methicillin-resistant Staphylococcus spp isolated in a teaching maternity hospital in the city of Natal, State of Rio Grande do Norte]

Analyses on 1,576 clinical specimens from hospitalized patients were performed with the aim of determining the prevalence of methicillin-resistant Staphylococcus spp isolated in the Januário Cicco Teaching Maternity Hospital in Natal, Rio Grande do Norte, in 2002 and 2003. The samples were collected, processed and identified according to standard procedures, for each clinical specimen. In vitro susceptibility profiles were obtained using the Kirby-Bauer method. 188 strains of Staphylococcus spp were isolated: 105 were identified as Staphylococcus aureus and 83 as coagulase-negative Staphylococcus. Staphylococcus aureus was isolated most often in secretions, whereas coagulase-negative Staphylococcus was most prevalent in blood cultures. The high (41.5%) prevalence of methicillin-resistant Staphylococcus spp shows the need for immediate prophylactic measures aimed at impeding the dissemination of this phenomenon.

Extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in paediatric wards: a nested case-control study

AIM

A high rate (48.6%) of extended spectrum beta-lactamase production among Klebsiella pneumoniae (ESBL-KP) clinical isolates in the paediatric wards of our hospital prompted the introduction of enhanced infection control measures, and after the implementation of these measures, we instituted a prospective surveillance programme, with a nested case-control study to determine the risk factors for rectal colonisation by ESBL-KP.

METHODS

Over a 1-year period, rectal swabs from patients and samples from the environment and the hands of health-care workers were cultured. Strain typing of ESBL-KP isolates was performed using pulsed-field gel electrophoresis. Characteristics of patients who were colonised with ESBL-KP during hospital stay were compared with those of patients who remained negative for ESBL-KP. Multivariate analysis was performed with model-building using stepwise logistic regression to determine independent risk factors for ESBL-KP acquisition.

RESULTS

Forty (18.5%) of 216 patients became colonised with ESBL-KP. The strongest independent predictors of ESBL-KP colonisation were mechanical ventilation (odds ratio (OR): 4.28) and hospitalisation for longer than 14 days (OR: 6.97). Genotyping of the isolates indicated probable patient-to-patient transmission; however, we could not determine the route of this spread. During the study period, a 1.6% rate of ESBL-KP clinical infection per 500 patient admissions was observed, in contrast to a 7% rate in the previous year.

CONCLUSIONS

Prolonged length of stay and mechanical ventilation were independent predictors of ESBL-KP colonisation. Enhanced infection control measures, antimicrobial stewardship and screening for rectal carriage were associated with a substantial decrease in paediatric units.

Comparison between qualitative and semiquantitative catheter-tip cultures: laboratory diagnosis of catheter-related infection in newborns

This prospective study evaluated semiquantitative and qualitative catheter-culture methods for diagnosis of catheter-related infection (CRI) in newborns. Catheter tips from newborns admitted to the Neonatal Unit of the University Hospital of the Botucatu Medical School, UNESP were included in the study. Catheter cultures were performed with both semiquantitative and qualitative techniques. For CRI diagnosis, microorganisms isolated from catheter cultures and from peripheral blood cultures were identified and submitted to agent susceptibility test. The gold standard was the certain CRI diagnosis when same microorganism (specie and profile of susceptibility to agents) was isolated from both catheter tips and peripheral blood culture. A total of 85 catheters from 63 newborns were included in the study. The semiquantitative culture method, despite presenting lower sensitivity (90%), showed higher specificity (71%) when compared to 100% of sensitivity and 60% of specificity in the qualitative method. The identification of the microorganisms obtained from the catheter cultures showed a prevalence of coagulase-negative staphylococci (CNS) species. The specie Staphylococcus epidermidis (77.5%) was the prevalent in the catheters with positive semiquantitative cultures. Among 11 episodes with CRI diagnosis, 8 (72.7%) were associated with CNS species, of which 6 were S. epidermidis. Two episodes of CRI by S. aureus and one by Candida parapsilosis were also detected. The semiquantitative catheter-culture method showed advantages for CRI diagnosis in newborns when compared to the conservative qualitative method.

Effectiveness of hand-washing teaching programs for families of children in paediatric intensive care units

AIMS

The authors developed a video-centred teaching program based on social learning principles to demonstrate hand-washing technique. A comparison was made between families who viewed the video and families who were taught the same techniques with the aid of an illustrated poster in terms of compliance and improvement in hand-washing skills.

BACKGROUND

Nosocomial infections are a significant cause of morbidity and mortality in paediatric intensive care unit patients. Hand hygiene is considered the most important preventive action against hospital-acquired infections. A number of studies have shown that increased compliance with hand-washing guidelines for health-care workers leads to decreases in nosocomial infection rates. Furthermore, recommendations have been made to ensure that parents who visit their children in intensive care units wash their hands first.

STUDY DESIGN

Quasi-experimental time series. Compliance and accuracy measurements were collected during one to five visits following the initial teaching intervention.

METHODS

A total of 123 families, who visited paediatric intensive care units, were recruited and assigned to two groups - one experimental (61 families) and the other a comparison group (62). Participants in the comparison group were taught hand-washing skills using simple illustrations. A 20-item hand-washing checklist was used to examine hand-washing compliance and accuracy.

RESULTS

No significant differences were noted in terms of demographics between the two groups. Results from a general estimated equation analysis showed that families in the experimental group had higher compliance and accuracy scores at statistically significant levels.

CONCLUSION

The video-based teaching program was effective in increasing compliance and accuracy with a hand-washing policy among families with children in intensive care units.

RELEVANCE TO CLINICAL PRACTICE

The education program is a simple, low-cost, low technology intervention for substantially reducing the incidence of nosocomial infection.

Prevention of catheter-related bloodstream infections in the neonatal intensive care setting

Nosocomial infection causes substantial morbidity and mortality among neonates treated in the neonatal intensive care setting. Colonization and subsequent infection of central venous catheters leading to catheter-related bloodstream infection is among the most common causes of nosocomial sepsis in this patient population. Prevention of catheter-related bloodstream infection is a major challenge and numerous strategies have been attempted in this context with varying success. Given the dynamic epidemiology of nosocomial infection among neonates and the emergence of antimicrobial resistance, novel prevention strategies are urgently required.

Infection in a neonate caused by Pichia fabianii: importance of molecular identification

Pichiafabianii, an uncommon yeast species recovered from clinical specimens, was documented as the cause of an infection in a 5-week-old female twin delivered at 25 and 3/7 weeks. She developed respiratory distress syndrome and necrotizing enterocolitis. At the time of the infection, she was febrile, thrombocytopenic, and still was requiring minimal ventilatory support. Blood cultures drawn on two consecutive days were positive for a germ tube negative yeast. Phenotypic methods including carbohydrate fermentations and assimilations (API 20C AUX) did not identify the yeast. Sequencing of D1/D2 domain of the large subunit rDNA was performed in one laboratory and sequencing a subunit of D2 performed in a second laboratory identified the yeast as P. fabianii. The organism was susceptible in vitro to amphotericin B, fluconazole and 5-fluorocytosinc. The patient responded to amphotericin B and removal of her vascular catheter. This case illustrates that there are an increasing number of fungi that may be pathogenic. Phenotypic tests may fail to identify them, emphasizing the need for commercially available, molecular based assays for identification.

Staphylococcal skin infections in children: rational drug therapy recommendations

Staphylococcus aureus remains one of the most common and troublesome of bacteria causing disease in humans, despite the development of effective antibacterials and improvement in hygiene. The organism is responsible for over 70% of all skin and soft tissue infections in children and accounts for up to one-fifth of all visits to pediatric clinics. Skin and soft tissue infections that are predominantly caused by S. aureus include bullous and non-bullous impetigo, folliculitis, furunculosis, carbunculosis, cellulitis, surgical and traumatic wound infections, mastitis, and neonatal omphalitis. Other skin and soft tissue infections may also be caused by S. aureus but are often polymicrobial in origin and require special consideration. These include burns, decubitus ulcers (particularly in the perianal region), puncture wounds of the foot, as well as human and mammalian bites. Treatment of staphylococcal skin infections varies from topical antiseptics to prolonged intravenous antibacterials, depending on severity of the lesions and the health of the child. The treatment of choice for oral antibacterials remains the penicillinase-resistant penicillins such as flucloxacillin. Cefalexin and erythromycin are suitable cost-effective alternatives with broader cover, although care must be taken with the use of macrolides because of development of resistance to multiple families of antibacterials, particularly the lincosamides. Other cephalosporins such as cefadroxil and cefprozil are also effective, can be given once daily and have a better tolerability profile -- while azithromycin has a further advantage of a 3-day course. However, all of these agents are more expensive. Although the antibacterials have been given for 10 days in most clinical trials, there is no evidence that this duration is more effective than a 7-day course. In children requiring intravenous therapy, ceftriaxone has a major advantage over other antibacterials such as sulbactam/ampicillin and cefuroxime in that it can be given once daily and may, therefore, be suitable for outpatient treatment of moderate-to-severe skin infections. Newer-generation cephalosporins and loracarbef are also effective and have a broader spectrum of activity, but do not offer any added benefit and are significantly more expensive. Skin and soft tissue infections due to methicillin-resistant S. aureus (MRSA) are still relatively uncommon in children. Well children with community-acquired MRSA infections can be treated with clindamycin or trimethoprim-sulfamethoxazole (cotrimoxazole), but must be observed closely for potentially severe adverse effects. In severe infections, vancomycin remains the treatment of choice, while intravenous teicoplanin and clindamycin are suitable alternatives. Linezolid and quinupristin/dalfopristin are currently showing great promise for the treatment of multi-resistant Gram-positive infections. While the choice of antibacterial is important, supportive management, including removal of any infected foreign bodies, surgical drainage of walled-off lesions, and regular wound cleaning, play a vital role in ensuring cure.

Investigation of the clonal dissemination of Klebsiella pneumoniae isolates producing extended-spectrum beta-lactamases in a neonatal ward, Sousse, Tunisia

This study was designed to investigate the spread of extended-spectrum beta-lactamase producing Klebsiella pneumoniae (ESBL-Kp) strains in Sousse hospital, during 7-month period by using phenotypic and genotypic markers. A total of 57 clinical isolates of ESBL-Kp, 22 strains recovered from seriously infected neonates and 35 strains recovered from colonized neonates and hospitalized in the neonatal ward of Sousse hospital, Tunisia, was subjected to 99 carbon source utilization tests, ribotyping and pulse-field gel electrophoresis (PFGE) profiles of total genomic DNA. Biotyping, ribotyping and PFGE typing showed that four different clones circulated in the neonatal ward between January and July 1997 and suggested that the epidemic strain belonged to the same biotype, ribotype and PFGE pattern, and was represented by 18 isolates from infected neonates and 28 isolates from colonized neonates. Biotyping, ribotyping and PFGE typing appeared to be reliable methods for distinguishing K. pneumoniae strains. Biotyping, which has the advantage of simplicity and rapidity, may be used as a first screening method.

Prevention and treatment of nosocomial sepsis in the NICU

Nosocomial sepsis is a serious problem for neonates who are admitted for intensive care. It is associated with an increase in mortality, morbidity, and prolonged length of hospital stay. Thus, both the human and fiscal costs of these infections are high. Although the rate of nosocomial sepsis increases with the degree of both prematurity and low birth weight, no specific lab test has been shown to be very useful in improving our ability to predict who has a "real" blood-stream infection and, therefore, who needs to be treated with a full course of antibiotics. As a result, antibiotic use is double the rate of "proven" sepsis and we are facilitating the growth of resistant organisms in the neonatal intensive care unit. The purpose of this article is to describe simple changes in process, which when implemented, can reduce nosocomial infection rates in neonates and improve outcomes.

Late-onset infection and the role of antibiotic prescribing policies

PURPOSE OF REVIEW

Late-onset infection is a significant cause of morbidity and mortality in low-birth-weight and premature infants. Empirical antibiotic treatment is used as infants can deteriorate rapidly without treatment. Current data on the epidemiology of late-onset infection, the types of antibiotics used, duration of antibiotic use, and antibiotic prescribing policies are reviewed.

RECENT FINDINGS

Epidemiological data on late-onset sepsis is dominated by information concerning developed countries; large prospective data collections have been set up in many such countries. Recent data indicate that late-onset sepsis occurs in one-fifth of very-low-birth-weight infants. There are increasing concerns regarding antibiotic resistance. Antibiotic regimens that do not include third-generation cephalosporins produce less resistance. Strategies of antibiotic rotation have not been documented as producing a marked effect on the development of resistant micro-organisms, but there is a lack of randomized trials. Recommendations for preventing the spread of vancomycin-resistant enterococci, produced by the Hospital Infection Control Practices Advisory Committee, have been shown to be effective in a number of situations. Recent reports have documented the success of multidisciplinary, systems-orientated approaches for reducing neonatal nosocomial infection.

SUMMARY

Antibiotic prescribing policies have an important role to play in the treatment of late-onset neonatal infection. There is enough evidence to state that narrow-spectrum antibiotics should be used wherever possible and that potent broad-spectrum antibiotics should be kept in reserve. Ongoing prospective surveillance of infection rates, micro-organisms, resistance and antibiotic use is essential.

Adsorbed poly(ethyleneoxide)-poly(propyleneoxide) copolymers on synthetic surfaces: spectroscopy and microscopy of polymer structures and effects on adhesion of skin-borne bacteria

Poly(ethyleneoxide)-copoly(propyleneoxide) (PEO-PPO) polymer coatings were evaluated for their resistance to the attachment of the marker organism Serratia marcescens and the skin-borne bacteria Staphylococcus epidermidis. The copolymers were adsorbed onto poly(styrene) films-chosen as simplified physicochemical models of skin surfaces-and their surface characteristics probed by contact angle goniometry, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). These functional surfaces were then presented to microbial cultures, bacterial attachment was assessed by fluorescence microscopy and AFM, and the structures of the polymer films examined again spectroscopically. Surface characterization data suggest that the adsorbed copolymer was partially retained at the surface and resisted bacterial attachment for 24 h. Quantitative evaluation of cell attachment was carried out by scintillation counting of (14)C-labeled microorganisms in conjunction with plate counts. The results show that a densely packed layer of PEO-PPO copolymer can reduce attachment of skin commensals by an order of magnitude, even when the coating is applied by a simple adsorptive process. The work supports the hypothesis that adhesion of microorganisms to biological substrates can be reduced if a pretreatment with an appropriate copolymer can be effected in vivo.