Early mucosal colonisation and its role in prediction of invasive infection in neonates at risk of early onset sepsis
Failid
Kuupäev
2012-02-27
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Uurimistöö peamiseks eesmärgiks oli selgitada vastsündinute varase sepsise empiiriliseks raviks kasutatavate ravirežiimide (ampitsilliin ja penitsilliin kombinatsioonis gentamütsiiniga) mõju vastsündinute rektaalse ja ninaleelu kolonisatsioonile oportunistlike mikroobidega. Lisaks sellele hinnati perinataalsete, neonataalsete ja keskkonna faktoreite osa limaskestade kolonisatsiooni tekkes; seost kolonisatsiooni ja infektsioone põhjustavate mikroobitüvede vahel; ning kaks korda nädalas kogutud järelevalvekülvide olulisust sepsise prognoosimisel.
Meetodid. Prospektivine, kahekeskuseline, klaster-randomiseeritud avatud uuring viidi läbi Tallinna Lastehaigla ja Tartu Ülikooli Kliinikumi laste- ja vastsündinute intensiivravi osakondades 02.08.2006 kuni 30.11.2007. Uuringusse kaasati 278 vastsündinut, kes olid osakonda saabudes nooremad kui 72 tundi, vajasid sepsise kahtluse või riskifaktorite olemasolu tõttu empiirilist antibakteriaalset ravi ning viibisid osakonnas vähemalt 24 tundi. Limaskestade kolonisatsiooni hindamiseks koguti nina-neelu materjal (n=1153) ja rektaalkaabe (n=1250) patsiendi osakonda saabumisel ja edaspidi kaks korda nädalas kuni osakonnas viibimise lõpuni või kuni 60-da ravipäevani. Uuringumaterjalid steriilsetest kehavedelikest (n=554) võeti patsiendi osakonda saabumisel enne antibakteriaalse ravi alustamist ja edaspidi vastavalt kliinilisele vajadusele. Materjal mikrobioloogilisteks uuringuteks külvati veri-, MacConkey ja Sabouraud agarile ning ampitsilliin-resistentsete tüvede selgitamiseks MacConkey agarile, kuhu oli lisatud 16 µg/ml ampitsilliini. Molekulaarseid uuringuid kasutati limaskestade ja invasiivsete tüvede klonaalsuse selgitamiseks. Nii emapoolsete kui ka keskkonnast ja lapsest sõltuvate kolonisatsiooni riskifaktorite (n=22) selgitamiseks kasutati ühest ja mitmest logistilist regressiooni. Järelevalvekülvide väärtuse hindamiseks sepsise prognoosimisel arvutati eraldi sensitiivsus, spetsiifilisus ning positiivne (PPV) ja negatiivne prognostiline väärtus iga võetud külvi kui ka patsiendi kohta.
Tulemused ja järeldused. Esmased seedetrakti koloniseerijad olid Gram-positiivsed bakterid, milledest ülekaalukalt domineerisid koagulaas negatiivsed stafülokokid. 49-l (17,8%) esines rektaalne kolonisatsioon Candida spp-ga. Isoleeritud rektaalsest ja nina-neelu materjalist esines vastavalt 55,8%-l ja 42,8%-l Gram-negatiivseid mikroobe. Kuigi antud kahe piirkonna mikroobne kooslus oli sarnane, esines siiski ka piirkonna valikulist mõju. Näiteks oli rektaalselt võrreldes nina-neeluga 1,5-2,5 korda suurem šanss kolonisatsiooniks enterobakteritega ja väiksem šanss (OR=0,52; 95% CI 0,30-0,89) Acinetobacter spp-ga. Selgus, et limaskestade kolonisatsiooni E. coli, K. oxytoca ja C. albicans’ga mõjutasid peamiselt emapoolsed ja perinataalsed faktorid, kusjuures kolonisatsioon K. pneumoniae, E. cloaceae, MRSA ja mitte-albicans-Candida’ga oli peamiselt tingitud haigla keskkonnast ja lapse enneaegsusest. Riskifaktorite mõju (näiteks haiglas viibimise aeg, osakond, gestatsiooni vanus, sünniviis) sooletrakti ja nina-neelu kolonisatsioonile nii antibiootikum-tundlike kui ka ravimresistentsete tüvede osas oli sarnane, omavahel tihedalt seotud ja mikroobispetsiifiline ning seetõttu on neid võimalik üldistada mõlemale piirkonnale.
Võrreldes ampitsilliini, kui laiema toimespektriga antibiootikumi mõju penitsilliiniga, võib väita, et esmamainitu toimet Gram-negatiivsele mikrofloorale ja ravimresistentsete tüvede tekkele on ilmselt ülehinnatud. Siiski esines valikulist mõju just Gram-positiivsele mikrofloorale. Näiteks koloniseeruti ampitsilliinravi korral võrreldes penitsilliiniga rohkem S. haemolyticus´e (erinevus +0,7; p=0,039) ja S. hominis´ga (+1,9, p=0,003), kuid vähem S. aureus’e (-1,9; p=0,006) ja enterokokkidega (-1,2; p<0,001). Seega peaks ravimrežiimi eelistus baseeruma lokaalsel olukorral; st millised on vastava osakonna sagedasemad infektsioonitekitajad ja nende ravimtundlikkus. Samuti tuleks arvestada enneaegsust ja muid lapsest sõltuvaid faktoreid.
Eelnev limaskestade kolonisatsioon Gram-negatiivsete oportunistlike mikroobide ja MRSA-ga võib olla aluseks invasiivse infektsiooni väljakujunemisele. Siiski on järelevalvekülvide sensitiivsus, spetsiifilisus ja PPV invasiivse infektsiooni tekke prognoosimiseks madalad (väärtused vastavalt 27%, 66% ja 4%) ja seega on nad väheefektiivsed. Samuti on nende kogumine küllalt kulukas ja aeganõudev. Siiski on järelevalvekülve mõttekas koguda teatud spetsiifiliste mikroobide (K. pneumoniae, MRSA) poolt põhjustatud haiglainfektsioonide puhangute korral. See aitaks parandada infektsioonikontrolli meetmeid ja oleks abiks empiirilise ravi valikul.
The general aim of the study was to compare how antibiotics commonly used for empiric therapy of EOS (ampicillin or penicillin both combined with gentamicin) influence the development of gut and nasopharyngeal (NP) microbiota and to define which of the abovementioned regimens should be preferred in terms of mucosal colonisation. Besides it, the aims were also addressed to identify independent perinatal, neonatal, and environmental factors influencing the colonisation process; to identify the relatedness of microorganisms isolated from NP and rectum to isolates form sterile sites and thus characterize their potential for causing invasive disease; and to define the value of twice a week collected surveillance cultures in predicting Gram-negative late onset sepsis (LOS) in high risk neonates admitted to NICU. Study design and methods. The prospective open label two centre cluster randomised study was conducted between August 2, 2006 and November 30, 2007 in NICUs of Tartu University Hospital and Tallinn Children’s Hospital. Neonates were included in the study (n=278) if they were younger than 72 hours, needed early empiric antibiotic treatment on clinical suspicion and/or due to risk factors of infection and were expected to stay in the unit for >24 hours. Rectal (n=1250) and NP (n=1153) specimens were collected on admission and then twice a week until discharge or Day 60 whichever occurred first. From patients receiving artificial lung ventilation tracheal aspirate (n=60) instead of NP swab was collected. Normally sterile body fluids (n=554) were cultured preferably before administration of antibiotics on admission and then if clinical condition deteriorated and symptoms suggestive of neonatal sepsis. Rectal swabs were plated onto blood agar, MacConkey agar for isolation of Gram-negative bacteria, and Sabouraud agar for isolation of yeasts. NP specimens were plated onto McConkey agar. All samples were also plated onto MacConkey agar with 16 μg/ml of ampicillin for the detection of Gram-negative ampicillin-resistant (AR) strains. The molecular analysis was performed for detection relatedness of mucosal and invasive strains. The sensitivity, specificity, negative and positive predictive values of surveillance cultures of 2108 mucosal and corresponding invasive culture pairs were calculated in predicting Gram-negative late-onset sepsis. The association between colonization by different microbes and a total of 22 maternal or neonatal predefined risk factors was assessed by using univariate and multiple logistic regression analyses. Results and conclusions. The first colonizers in neonates admitted to NICU with risk factors of EOS were Gram-positive bacteria, among which coagulase negative staphylococci clearly predominated. Colonization by Gram-negatives in NP and rectal area were similar. The frequent opportunistic colonizers were also frequent causative agents of LOS. The mucosal colonisation by E. coli, K. oxytoca and C. albicans is mainly influenced by maternal and early perinatal factors, while K. pneumoniae, E. cloacae, MRSA and non-albicans Candida spp. are predominantly affected by the hospital environment and prematurity. Risk factors (e.g. duration of NICU stay, unit, gestation age, route of delivery) influencing NP and rectal colonisation including AR strains are similar and species-specific and are closely inter-related making extrapolations from one site to the other feasible. In patients with risk factors for EOS the impact of ampicillin (a broader spectrum antibacterial agent compared with penicillin) on mucosal colonisation with Gram-negative microorganisms including AR strains may have been over-estimated. The main differences between these two agents are as follows: patients receiving ampicillin containing regimen are less frequently colonised with S. aureus and Enterococcus spp. but more often colonised with S. haemolyticus and S. hominis than those treated with penicillin. Thus, the avoidance of unwanted initial gut colonisation should not be a limiting factor in choosing between ampicillin and penicillin for the empiric treatment of EOS. We suggest that the selection should be made mainly according to the local distribution of EOS causing microorganisms and their antibiotic susceptibility. Host-related factors like the degree of prematurity should also be considered. Prior mucosal colonization with Gram-negative opportunistic micro-organisms and MRSA may lead to invasive disease. However, the sensitivity, specificity and PPVs of mucosal surveillance samples in predicting invasive disease is moderate for Enterobacteriaceae and suboptimal for non-fermentative micro-organisms. So, routine and non-targeted surveillance cultures are not efficient in predicting LOS in NICU as they are of low diagnostic accuracy, expensive and time consuming. Targeted for specific organisms, surveillance cultures may prove to be useful especially during outbreaks of nosocomial infections. They may offer an opportunity to improve infection control measures, to cohort patients and to select the most appropriate empiric antibiotic regimen.
The general aim of the study was to compare how antibiotics commonly used for empiric therapy of EOS (ampicillin or penicillin both combined with gentamicin) influence the development of gut and nasopharyngeal (NP) microbiota and to define which of the abovementioned regimens should be preferred in terms of mucosal colonisation. Besides it, the aims were also addressed to identify independent perinatal, neonatal, and environmental factors influencing the colonisation process; to identify the relatedness of microorganisms isolated from NP and rectum to isolates form sterile sites and thus characterize their potential for causing invasive disease; and to define the value of twice a week collected surveillance cultures in predicting Gram-negative late onset sepsis (LOS) in high risk neonates admitted to NICU. Study design and methods. The prospective open label two centre cluster randomised study was conducted between August 2, 2006 and November 30, 2007 in NICUs of Tartu University Hospital and Tallinn Children’s Hospital. Neonates were included in the study (n=278) if they were younger than 72 hours, needed early empiric antibiotic treatment on clinical suspicion and/or due to risk factors of infection and were expected to stay in the unit for >24 hours. Rectal (n=1250) and NP (n=1153) specimens were collected on admission and then twice a week until discharge or Day 60 whichever occurred first. From patients receiving artificial lung ventilation tracheal aspirate (n=60) instead of NP swab was collected. Normally sterile body fluids (n=554) were cultured preferably before administration of antibiotics on admission and then if clinical condition deteriorated and symptoms suggestive of neonatal sepsis. Rectal swabs were plated onto blood agar, MacConkey agar for isolation of Gram-negative bacteria, and Sabouraud agar for isolation of yeasts. NP specimens were plated onto McConkey agar. All samples were also plated onto MacConkey agar with 16 μg/ml of ampicillin for the detection of Gram-negative ampicillin-resistant (AR) strains. The molecular analysis was performed for detection relatedness of mucosal and invasive strains. The sensitivity, specificity, negative and positive predictive values of surveillance cultures of 2108 mucosal and corresponding invasive culture pairs were calculated in predicting Gram-negative late-onset sepsis. The association between colonization by different microbes and a total of 22 maternal or neonatal predefined risk factors was assessed by using univariate and multiple logistic regression analyses. Results and conclusions. The first colonizers in neonates admitted to NICU with risk factors of EOS were Gram-positive bacteria, among which coagulase negative staphylococci clearly predominated. Colonization by Gram-negatives in NP and rectal area were similar. The frequent opportunistic colonizers were also frequent causative agents of LOS. The mucosal colonisation by E. coli, K. oxytoca and C. albicans is mainly influenced by maternal and early perinatal factors, while K. pneumoniae, E. cloacae, MRSA and non-albicans Candida spp. are predominantly affected by the hospital environment and prematurity. Risk factors (e.g. duration of NICU stay, unit, gestation age, route of delivery) influencing NP and rectal colonisation including AR strains are similar and species-specific and are closely inter-related making extrapolations from one site to the other feasible. In patients with risk factors for EOS the impact of ampicillin (a broader spectrum antibacterial agent compared with penicillin) on mucosal colonisation with Gram-negative microorganisms including AR strains may have been over-estimated. The main differences between these two agents are as follows: patients receiving ampicillin containing regimen are less frequently colonised with S. aureus and Enterococcus spp. but more often colonised with S. haemolyticus and S. hominis than those treated with penicillin. Thus, the avoidance of unwanted initial gut colonisation should not be a limiting factor in choosing between ampicillin and penicillin for the empiric treatment of EOS. We suggest that the selection should be made mainly according to the local distribution of EOS causing microorganisms and their antibiotic susceptibility. Host-related factors like the degree of prematurity should also be considered. Prior mucosal colonization with Gram-negative opportunistic micro-organisms and MRSA may lead to invasive disease. However, the sensitivity, specificity and PPVs of mucosal surveillance samples in predicting invasive disease is moderate for Enterobacteriaceae and suboptimal for non-fermentative micro-organisms. So, routine and non-targeted surveillance cultures are not efficient in predicting LOS in NICU as they are of low diagnostic accuracy, expensive and time consuming. Targeted for specific organisms, surveillance cultures may prove to be useful especially during outbreaks of nosocomial infections. They may offer an opportunity to improve infection control measures, to cohort patients and to select the most appropriate empiric antibiotic regimen.
Kirjeldus
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Märksõnad
enneaegsed lapsed, vastsündinud, sepsis, limaskest, kolonisatsioon, aeroobsed bakterid, antimikroobne ravi, premature infants, newborns, antimicrobial therapy, aerobic bacteria, colonization, sepsis