Mercedes Sananes

Bloodstream infections in a neonatal intensive-care unit: 12 years' experience with an antibiotic control program.

OBJECTIVE To assess the prevalence of gram-positive coccal (GPC), gram-negative bacillary (GNB), and fungal blood-stream infections (BSIs) during a 12-year period in which a consistent antibiotic treatment protocol was in place; to evaluate the efficacy of these antibiotic policies in relation to treatment, to the emergence of bacterial or fungal resistance, and to the occurrence of infection outbreaks or epidemics. STUDY DESIGN Case series. METHODS Demographic, clinical, and bacteriological information from 363 infants born during 1986 through 1991 and 1992 through 1997 who developed 433 blood-culture-proven BSIs was analyzed. Early-onset BSIs were defined as those infections discovered within 48 hours of birth, and late-onset BSIs as those that occurred thereafter. Suspected early-onset BSIs were treated with ampicillin and gentamicin, and suspected late-onset BSIs with vancomycin and gentamicin. Antibiotics were changed on the basis of organism antimicrobial susceptibility. RESULTS Early-onset BSIs were noted in 52 of 21,336 live births and 40 of 20,402 live births during 1986 through 1991 and 1992 through 1997, respectively. GPC (83% due to group B streptococcus [GBS]) accounted for approximately one half of early-onset BSI cases and GNB (68% Enterobacteriaceae) for the remainder. Early-onset GBS declined from 24 to 11 cases (P=.04) and late-onset BSI increased from 111 to 230 cases (P<.01) from the first to the last study period. Sixty-eight percent of late-onset BSIs were due to GPC (primarily coagulase-negative Staphylococcus), 18% to GNB, and 14% to fungus. Over the study period, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa isolated from the newborn intensivecare unit (unlike those strains from other hospital units) remained fully susceptible to ceftazidime and gentamicin. Although the hospitalwide prevalence of methicillin-resistant Staphylococcus aureus increased, all 17 newborn BSI cases were due to methicillin-sensitive strains. Prevalence of methicillin-resistant coagulase-negative Staphylococcus increased, although all strains remained vancomycin-susceptible, as did the 16 Enterococcus faecalis isolates. All fungi recovered (from 48 patients) were susceptible to amphotericin. CONCLUSION We observed a decrease in the prevalence of early-onset BSIs due to GBS and an increase in late-onset BSIs due to GPC, GNB, and fungi. The combination of ampicillin and gentamicin for suspected early-onset BSIs and vancomycin and gentamicin for late-onset BSIs has been successful for treatment of individual patients without the occurrence of infection outbreaks or the emergence of resistance. Controlled antibiotic programs and periodic evaluations based on individual unit and not on hospitalwide antibiograms are advisable.

Comparison of a closed (Trach Care MAC) with an open endotracheal suction system in small premature infants.

OBJECTIVE:To determine whether ventilated, low birth weight infants treated with closed versus open tracheal suction in a neonatal intensive care unit (NICU) differ as to airway bacterial colonization, nosocomial pneumonia, bloodstream infection (BSI), incidence and severity of bronchopulmonary dysplasia (BPD), neonatal mortality, frequency of suction, reintubation, and nurse preference.STUDY DESIGN:A total of 175 low birth weight infants (≤1250 gm) consecutively born (1997 to 1999), intubated, and ventilated in the delivery room were randomized on admission to the NICU to a closed (Trach Care MAC) or open suction group. Closed multi-use catheters were changed daily; open catheters were changed after every use. Two-pass endotracheal suctioning (both groups) was performed every 8 hours or as needed. Side-port connectors were not used; thus open suction required disconnection from ventilators. Tracheal aspirate cultures were obtained on admission and weekly thereafter. Nosocomial BSI (occurring after 48 hours of life) was documented by positive blood cultures. Radiographs taken before, during, and after tracheal aspirate cultures or BSIs were graded using a semiquantitative system for pneumonia and a modified score for BPD. Nurse preference regarding suction method was recorded.RESULTS:Of the original 175 patients, 10 (5 from each group) died and 32 others (16 from each group) were extubated at or before 7 days of life. The study population comprised 67 patients in the closed group and 66 in the open group who were ventilated longer than 1 week. Groups were not statistically different in terms of demographic and clinical characteristics, such as birth weight (837 vs 876 gm), ventilation (27 vs 26 days), and length of stay (49 vs 40 days). Airway colonization with Gram-positive cocci occurred in the majority of patients by 2 weeks of life, regardless of group. A total of 39% of infants in the closed group and 44% of infants in the open group became airway colonized with Gram-negative bacilli; differences were statistically significant. No Gram-negative bacilli species was more likely to be associated with either suction. Nosocomial pneumonia was diagnosed in five patients from each group. Nosocomial BSIs occurred in six closed suction infants and five open suction infants. A comparable number of infants in each group developed severe BPD and were discharged from the hospital on oxygen. A total of 28% of closed suction patients and 27% of open suction patients died. Infants in the closed versus open group were suctioned on average 4.4 and 4.1 times per day and were reintubated 9.7 and 8.6 times per 100 ventilator days, respectively. A total of 40 of 44 NICU nurses considered closed suction to be easier to use, less time-consuming, and better tolerated by the patient.CONCLUSIONS:Closed suction obviates the physiological disadvantage of ventilator disconnection without increasing the rate of bacterial airway colonization, frequency of endotracheal suction and reintubation, duration of mechanical ventilation, length of hospitalization, incidence of nosocomial pneumonia, nosocomial BSI, severity of BPD, and neonatal mortality. Although slightly more expensive, closed suction is perceived by nursing staff to be easier, less time-consuming, and better tolerated by small premature infants requiring mechanical ventilation for ≥1 week.

Purulence and gram-negative bacilli in tracheal aspirates of mechanically ventilated very low birth weight infants.

OBJECTIVE: Tracheal aspirates (TAs) from mechanically ventilated very low birth weight (VLBW) infants are frequently obtained during the evaluation of suspected sepsis, tracheitis, or ventilator-associated pneumonia (VAP). Purulence and bacteria in Gram stain of bronchopulmonary secretions are considered signs of respiratory infection, and medical decisions are made on the assumption that they are predictors of positive bacterial tracheal cultures (TCs). The purpose of this retrospective investigation was to establish the relationship of purulence and bacteria in TA from ventilated VLBW infants with positive TC and to identify its clinical significance.STUDY DESIGN: One hundred and seventy consecutively born VLBW infants (1996 to 1998) who remained on mechanical ventilation longer than 1 week were studied. Demographic, laboratory, and clinical data were obtained from hospital medical records. Purulence, defined by the number of polymorphonuclear leukocytes (PMNs) per low power field (LPF), was reported as light (<25 PMNs/LPF) or moderate/heavy (≥25 PMNs/LPF) for every TA.RESULTS: Purulence was absent in 469 of 646 (72%) TA taken from 170 infants. Light purulence was present in 17% and moderate/heavy purulence in 11%. TCs were positive in 58% of non-purulent, 94% of light, and 100% of moderate/heavy purulent TA. Bacteria on Gram stain were present in 12% of non-purulent, 70% of light purulent, and 83% of moderate/heavy purulent TA. Moderate/heavy purulence in TA was predictive of a positive TC with Gram-negative bacilli (GNB) with 70% sensitivity, 100% specificity, 100% positive predictive value, and 67% negative predictive value. Purulence in TA, as well as GNB airway colonization, became more frequent as mechanical ventilation progressed and was not associated with a particular GNB species. There were 79 infants who never had purulent TA and 91 who, at some time during the hospitalization, did. At the time of first purulent TA, 65 (71%) of 91 infants were asymptomatic. Twenty-six infants (29%) had clinical deterioration for which they underwent sepsis work-up. Three had blood stream infection, 5 VAP, 5 tracheitis, and 13 respiratory complications of non-infectious etiology. Four of five VAP infants died; all others survived.CONCLUSION: In VLBW infants, purulence in TA is associated with prolonged endotracheal intubation and is temporally related to GNB airway colonization. At the time of the first purulent TA, the majority of mechanically ventilated VLBW infants are asymptomatic. Only a few symptomatic VLBW infants had nosocomial respiratory infection. Understanding the clinical significance of purulence and GNB in TA from this unique patient population is important for management and prognosis, and it may decrease concern for infection and the associated use of antibiotics.

Radiological Pulmonary Changes in Neonates at the Time of Nosocomial Blood Stream Infection (BSI) or during Airway Colonization with Pseudomonas Aeruginosa

Radiological Pulmonary Changes in Neonates at the Time of Nosocomial Blood Stream Infection (BSI) or during Airway Colonization with Pseudomonas Aeruginosa

Purulence and Gram Negative Bacilli in Tracheal Aspirates of Mechanically Ventilated Neonates

Purulence and Gram Negative Bacilli in Tracheal Aspirates of Mechanically Ventilated Neonates

Mechanically Ventilated Newborns: A Comparison of Two Airway Suctioning Regimens 1228

Tracheal suctioning (TS) although clinically necessary may cause hypoxemia, bradycardia, bacteremia and airway colonization. We hypothesize that some reduction of TS frequency will not adversely affect newborn care. In our NICU, TS was done q4h, but since in August 1997 the frequency was changed to q8h or as needed, a comparison of these two regimens was undertaken. TS (2 passes) was preceded by the instillation of 0.2 ml saline. Consistency, amount and color of secretions was documented. Data from 24 (q4h) and 24 (q8h) infants(bwgt. ≤1500g) on conventional ventilation for ≥7 days were analyzed. Variables studied included: reintubations (RTUB), postural drainages (PD), the incidence of bloodtinged secretions and airway colonization with Gram Positive Cocci (GPC) or Gram Negative Bacilli (GNB). Demographic and perinatal factors among the groups were similar. Infants in the q4h group (bwgt. 900g, 27w GA, 23 survivors) were comparable to those of the q8h group (bwgt. 952g, 27w GA, 23 survivors). Average number of TS/pt/d was 6 and 4.6 for q4h and q8h groups, respectively. Similar differences in TS frequency were noted at 7, 14 and 21days (p<0.01). Two pts. in the q8h group experienced nosocomial bloodstream infection (1 GPC, 1 GNB) unrelated to airway colonization. During hospitalization, newborns from both groups were RTUB on average 2.6 times, while 9 pts. (q4h) and 10 pts. (q8h) needed PD due to either atelectasis(often related to endotracheal tube malposition) or changes in quality/quantity of airway secretions. Blood-tinged secretions but not frank hemorrhage were noted during routine TS in 6 pts. (4 from q4h) and following RTUB in another 6 (5 from q8h). Eighteen pts. from each group were ventilated for at least 14 days. All but one had GPC (S.hemolyticus and/or S.epidermidis) and 22 of the 36 (q4h/q8h combined pts.) had GNB colonization. Equally distributed between the groups were:P.aeruginosa (7), H.influenzae (1), A.baumannii(2), K.pneumoniae (7), E.cloacae (1) and E.coli(4) isolates. Conclusion: A significant reduction in TS can be accomplished without affecting neonatal mortality, number of RTUB, need for PD, and timing and type of airway colonization. Significant cost benefits may be anticipated when comparable changes in the frequency of tracheal suctioning are implemented.

Epidemiology of Gram Negative Bacilli (GNB) Airway Colonization in an NICU 1203

GNB airway colonization occurs in one-third of newborns who are mechanically ventilated for longer than 2 weeks. This colonization is associated with significant morbidity and mortality. To ascertain their origin and potential modes of transmission, 52 GNB isolates from 14 ventilated newborns were analyzed by pulsed-field gel electrophoresis (PFGE). These isolates were from 41 serial tracheal cultures obtained (July-October 1997) at the NICU where pts. were located in four contiguous rooms. Routine bacteriology showed that five neonates were colonized with two different GNB and one was colonized with three. PFGE analysis revealed that one pt. acquired two strains and one subtype of Klebsiella (A1,E, E1), and another harbored multiple subtypes of Klebsiella(A,A1,A2,A3). For the remaining pts., colonizations were due to unrelated strains. Table

Failure to Eradicate Gram Negative Bacilli (GNB) Airway Colonization in Mechanically Ventilated Newborns. † 1229

GNB airway colonization in mechanically ventilated neonates is associated with significant morbidity and mortality. We reviewed our experience (1991-97) with antibiotic treatment for GNB airway colonization defined by the presence of these organisms in two or more tracheal cultures (TC). One-hundred forty infants (96% survival, of an average 975g bwgt., 28w GA, 37d on ventilator, 64d hospitalization) born in our Medical Center became GNB airway colonized after the second week of life. No patient experienced GNB nosocomial blood stream infection (BSI). Forty-six infants did not have TCs after Tx, therefore were excluded. For 80 of the remaining 94 neonates, the decision to treat colonization was made by the attending in 14/15 P. aeruginosa, 5/5 S. marcescens, 2/3 A.baumannii, 22/24 K. pneumoniae, 4/4 C.koseri, 13/17 E. coli, 20/26E. cloacae cases. Antibiotic selection (at standard recommended doses) included: gentamicin 55 pts, ceftazidime alone or with gentamicin 18 pts., tobramycin, ampicillin-sulbactam, clindamycin or mezlocillin for the remaining 7 pts. One K.pneumoniae and one E. coli colonized pt. was treated with ceftazidime and gentamicin respectively and became TC negative. All others remained TC positive. In 4 of these pts. repeated Tx also failed to eradicate GNB. During the same period, 59 of approximately 6000 other NICU infants experienced 62 GNB nosocomial BSI due to A. baumannii (1), P. aeruginosa (5), S. marcescens (5), K. pneumonia (18), E.cloacae (13) and E. coli (20). All pseudomonas and 3 of the klebsiella cases died; the remaining infants responded to treatment. At the time of the positive blood cultures, 28% of the patients were airway colonized with the same GNB and 44% of the uncolonized infants became TC positive. Following Tx, half of the latter became TC negative and the other half remained airway colonized. During the study period, antibiotic susceptibilities were greater for GNB isolates obtained from blood than for those isolates from TC. Conclusion: standard antibiotic Tx cannot eradicate GNB airway colonization, but satisfactory responses to Tx can be expected in the majority of BSI. GNB airway colonization will follow BSI in about one-fourth of the cases. Failure to eradicate organisms may be due to low antibiotic concentration in the airway, reduced susceptibility of colonizing strains or persistent GNB translocation from the gastrointestinal tract.