Core outcome set for perinatal interventions for congenital diaphragmatic hernia

OBJECTIVE

To develop a core set of prenatal and neonatal outcomes for clinical studies evaluating perinatal interventions for congenital diaphragmatic hernia, using a validated consensus-building method.

METHODS

An international steering group comprising 13 leading maternal-fetal medicine specialists, neonatologists, pediatric surgeons, patient representatives, researchers and methodologists guided the development of this core outcome set. Potential outcomes were collected through a systematic review of the literature and entered into a two-round online Delphi survey. A call was made for stakeholders with experience of congenital diaphragmatic hernia to review the list and score outcomes based on their perceived relevance. Outcomes that fulfilled the consensus criteria defined a priori were discussed subsequently in online breakout meetings. Results were reviewed in a consensus meeting, during which the core outcome set was defined. Finally, the definitions, measurement methods and aspirational outcomes were defined in online and in-person definition meetings by a selection of 45 stakeholders.

RESULTS

Overall, 221 stakeholders participated in the Delphi survey and 198 completed both rounds. Fifty outcomes met the consensus criteria and were discussed and rescored by 78 stakeholders in the breakout meetings. During the consensus meeting, 93 stakeholders agreed eventually on eight outcomes, which constituted the core outcome set. Maternal and obstetric outcomes included maternal morbidity related to the intervention and gestational age at delivery. Fetal outcomes included intrauterine demise, interval between intervention and delivery and change in lung size in utero around the time of the intervention. Neonatal outcomes included neonatal mortality, pulmonary hypertension and use of extracorporeal membrane oxygenation. Definitions and measurement methods were formulated by 45 stakeholders, who also added three aspirational outcomes: duration of invasive ventilation, duration of oxygen supplementation and use of pulmonary vasodilators at discharge.

CONCLUSIONS

We developed with relevant stakeholders a core outcome set for studies evaluating perinatal interventions in congenital diaphragmatic hernia. Its implementation should facilitate the comparison and combination of trial results, enabling future research to better guide clinical practice. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal endoscopic tracheal occlusion reduces pulmonary hypertension in severe congenital diaphragmatic hernia

OBJECTIVE

Fetal endoscopic tracheal occlusion (FETO) is associated with increased perinatal survival and reduced need for extracorporeal membrane oxygenation (ECMO) in fetuses with severe congenital diaphragmatic hernia (CDH). This study evaluates the impact of FETO on the resolution of pulmonary hypertension (PH) in fetuses with isolated CDH.

METHODS

We reviewed retrospectively the medical records of all fetuses evaluated for CDH between January 2004 and July 2017 at a single institution. Fetuses with additional major structural or chromosomal abnormalities were excluded. CDH cases were classified retrospectively into mild, moderate and severe groups based on prenatal magnetic resonance imaging indices (observed-to-expected total fetal lung volume and percentage of intrathoracic liver herniation). Presence of PH was determined based on postnatal echocardiograms. Logistic regression analyses were performed to evaluate the relationship between FETO and resolution of PH by 1 year of age while controlling for side of the CDH, use of ECMO, gestational age at diagnosis, gestational age at delivery, fetal gender, sildenafil use at discharge and CDH severity. Resolution of PH by 1 year of age was compared between a cohort of fetuses with severe CDH that underwent FETO and a cohort that did not have the procedure (non-FETO). A subanalysis was performed restricting the analysis to isolated left CDH. Parametric and non-parametric tests were used for comparisons.

RESULTS

Of 257 CDH cases evaluated, 72% (n = 184) had no major structural or chromosomal anomalies of which 58% (n = 107) met the study inclusion criteria. The FETO cohort consisted of 19 CDH cases and the non-FETO cohort (n = 88) consisted of 31 (35%) mild, 32 (36%) moderate and 25 (28%) severe CDH cases. All infants with severe CDH, regardless of whether they underwent FETO, had evidence of neonatal PH. FETO (OR, 3.57; 95% CI, 1.05-12.10; P = 0.041) and ECMO (OR, 5.01; 95% CI, 2.10-11.96; P < 0.001) were independent predictors of resolution of PH by 1 year of age. A higher proportion of infants with severe CDH that underwent FETO had resolution of PH by 1 year after birth compared with infants with severe CDH in the non-FETO cohort (69% (11/16) vs 28% (7/25); P = 0.017). Similar results were observed when the analysis was restricted to cases with left-sided CDH (PH resolution in 69% (11/16) vs 28% (5/18); P = 0.032).

CONCLUSION

In infants with severe CDH, FETO and ECMO are independently associated with increased resolution of PH by 1 year of age. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Fetal lung volume and quantification of liver herniation by magnetic resonance imaging in isolated congenital diaphragmatic hernia

OBJECTIVE

To determine associations between fetal lung and liver herniation volumes measured by magnetic resonance imaging (MRI) and mortality/need for extracorporeal membrane oxygenation (ECMO) in cases of isolated congenital diaphragmatic hernia (CDH). A secondary objective was to compare prenatal MRI parameters with two-dimensional ultrasound lung measurements.

METHODS

A retrospective review of medical records of all fetuses with isolated CDH evaluated between January 2004 and July 2012 was performed. The following MRI parameters were measured at 20-32 weeks: observed/expected total fetal lung volume (o/e-TLV), predicted pulmonary volume (PPV), percentage of liver herniated into the fetal thorax (%LH) and the liver/thoracic volume ratio (LiTR). These were compared with the ultrasound-determined lung-to-head ratio (LHR) and the observed/expected LHR (o/e-LHR) in the same cohort. The predictive value of MRI and ultrasound parameters for mortality and the need for ECMO was evaluated by univariate, multivariate and factor analysis and by receiver-operating characteristics curves.

RESULTS

Eighty fetuses with isolated CDH were evaluated. Overall mortality was 18/80 (22.5%). Two newborns died a few hours after birth. ECMO was performed in 29/78 (37.2%) newborns, with a survival rate of 48.3% (14/29). The side of the diaphragmatic defect was not associated with mortality (P = 0.99) or the need for ECMO (P = 0.48). Good correlation was observed among o/e-TLV, PPV, LHR and o/e-LHR as well as between %LH and LiTR (r = 0.89; P < 0.01); however, fetal lung measurements and measures of liver herniation were not correlated (all P > 0.05). All parameters were statistically associated with mortality or the need for ECMO. The best combination of measurements to predict mortality was o/e-TLV and %LH, with 83% accuracy.

CONCLUSION

Mortality and the need for ECMO in neonates with isolated CDH can be best predicted using a combination of MRI o/e-TLV and %LH.

Urinary F2-isoprostanes are poor prognostic indicators for the development of bronchopulmonary dysplasia

OBJECTIVE

Oxygen toxicity is thought to contribute to the development of bronchopulmonary dysplasia (BPD). Oxidant injury leads to formation of F(2)-isoprostanes (F(2)-IsoP). We hypothesized that urinary excretion of the stable metabolite of F(2)-IsoP, 8-iso-PGF(2alpha), would be higher in infants who develop BPD than those who did not.

METHODS

Forty infants <30-weeks gestational age (GA) were enrolled, 24 infants with BPD and 16 without BPD. Urine specimens were collected weekly and stored at -80 degrees C until analyzed. Urinary 8-iso-PGF(2alpha) was measured by gas chromatography/mass spectrometry (GC-MS) and normalized to creatinine excretion.

RESULTS

GA and birth weight (BW) were lower in infants who developed BPD than those who did not. Urinary 8-iso-PGF(2alpha) levels in the first or third weeks of age were not significantly different between the two groups.

CONCLUSION

Urinary excretion of 8-iso-PGF(2alpha) in early postnatal life in preterm infants is not correlated with the development of BPD.

Evaluation of the MRSA-Screen Test in detecting oxacillin resistance in community and hospital isolates of Staphylococcus aureus

The MRSA-Screen Test (Denka Seiken Co., Japan), a latex agglutination test to detect penicillin-binding protein 2a, was compared with PCR for the detection of oxacillin resistance in Staphylococcus aureus. A total of 77 oxacillin-sensitive and 269 oxacillin-resistant (ORSA) isolates were evaluated. Of the ORSA isolates, 186 were non-multiresistant (NORSA), defined as being resistant to two or fewer antibiotics other than beta-lactams. Eighty-three were multiresistant ORSA (MORSA) strains. If PCR is considered the gold standard test, then the sensitivity, specificity, positive and negative predictive values of the MRSA-Screen Test were 100, 99, 99 and 100%, respectively. The endpoint was hard to read with NORSA strains that took longer than 60 s to react. MORSA strains took a median 12 s (range 5-60 s) to give a positive reaction with the MRSA-Screen Test, whereas NORSA strains took a median 30 s (range 5-180 s), a difference which was significantly different (P < 0.0001, two-tailed Mann-Whitney unpaired two sample test). NORSA strains had an MIC50 of 128 mg/l and MIC90 of 256mg/l, whereas MORSA strains had an MIC50 and MIC90 of >256mg/l. The time that the MRSA-Screen Test took to agglutinate with ORSA strains correlated weakly with the MIC (r2 = 0.26). Detection of methicillin resistance cost AUD$9 per isolate with the MRSA-Screen Test, compared with AUD$13 per isolate with mecA PCR. The MRSA-Screen Test gave excellent sensitivity and specificity, and was quicker and cheaper than PCR. The full 3 min should be allowed to elapse before calling a test negative. Organisms giving indeterminate reactions should be tested for the mecA gene by PCR.

In vitro activities of ertapenem (MK-0826) against recent clinical bacteria collected in Europe and Australia

Ertapenem (MK-0826, L-749,345) is a 1-beta-methyl carbapenem with a long serum half-life. Its in vitro activity was determined by broth microdilution against 3,478 bacteria from 12 centers in Europe and Australia, with imipenem, cefepime, ceftriaxone, and piperacillin-tazobactam used as comparators. Ertapenem was the most active agent tested against members of the family Enterobacteriaceae, with MICs at which 90% of isolates are inhibited (MIC(90)s) of < or =1 microg/ml for all species. Ertapenem also was more active than imipenem against fastidious gram-negative bacteria and Moraxella spp.; on the other hand, ertapenem was slightly less active than imipenem against streptococci, methicillin-susceptible staphylococci, and anaerobes, but its MIC(90)s for these groups remained < or =0.5 microg/ml. Acinetobacter spp. and Pseudomonas aeruginosa were also much less susceptible to ertapenem than imipenem, and most Enterococcus faecalis strains were resistant. Ertapenem resistance, based on a provisional NCCLS MIC breakpoint of > or =16 microg/ml, was seen in only 3 of 1,611 strains of the family Enterobacteriaceae tested, all of them Enterobacter aerogenes. Resistance was also seen in 2 of 135 anaerobes, comprising 1 Bacteroides fragilis strain and 1 Clostridium difficile strain. Ertapenem breakpoints for streptococci have not been established, but an unofficial susceptibility breakpoint of < or =2 microg/ml was adopted for clinical trials to generate corresponding clinical response data for isolates for which MICs were as high as 2 microg/ml. Of 234 Streptococcus pneumoniae strains tested, 2 required ertapenem MICs of 2 microg/ml and one required an MIC of 4 microg/ml, among 67 non-Streptococcus pyogenes, non-Streptococcus pneumoniae streptococci, single isolates required ertapenem MICs of 2 and 16 microg/ml. These streptococci also had diminished susceptibilities to other beta-lactams, including imipenem as well as ertapenem. The Etest and disk diffusion gave susceptibility test results in good agreement with those of the broth microdilution method for ertapenem.

Red blood cell transfusion does not increase oxygen consumption in critically ill septic patients

BACKGROUND

Red blood cell (RBC) transfusion is commonly used to increase oxygen transport in patients with sepsis. However it does not consistently increase oxygen uptake at either the whole-body level, as calculated by the Fick method, or within individual organs, as assessed by gastric intra-mucosal pH.

AIM

This study evaluates the hemodynamic and oxygen utilization effects of hemoglobin infusion on critically ill septic patients.

METHODS

Fifteen septic patients undergoing mechanical ventilation whose hemoglobin was <10 g% were eligible. Ten patients (APACHE II: 25.5 +/- 7.6) received an infusion of 1 unit of packed RBC over 1 h while sedated and paralyzed. The remaining five control patients (APACHE II: 24.3 +/- 6.0) received a 5% albumin solution (500 ml) over 1 h. Hemodynamic data, gastric tonometry and calorimetry were obtained prior to and immediately after RBC transfusion or 5% albumin infusion.

RESULTS

Transfusion of RBC was associated with an improvement in left ventricular systolic work index (38.6 +/- 12.6 to 41.1 +/- 13.0 g/min/m2; P = 0.04). In the control group there was no significant change in the left ventricular systolic work index (37.2 +/- 14.3 to 42.2 +/- 18.9 g/min/m2). An increase in pulmonary vascular resistance index (203 +/- 58 to 238 +/- 49 dyne/cm5/m2; P = 0.04) was also observed, while no change was produced by colloid infusion (237 +/- 87.8 to 226.4 +/- 57.8 dyne/cm5/m2). Oxygen utilization did not increase either by Fick equation or by indirect calorimetry in either group. Gastric intramucosal pH increased only in the control group but did not reach statistical significance.

CONCLUSION

Hemoglobin increase does not improve either global or regional oxygen utilization in anemic septic patients. Furthermore, RBC transfusion may hamper right ventricular ejection by increasing the pulmonary vascular resistance index.

Mitochondrial glutathione and oxidative stress: implications for pulmonary oxygen toxicity in premature infants

Administration of supplemental oxygen, despite being an important clinical therapy, can cause significant lung damage. Because they have underdeveloped lungs, prematurely born human infants frequently require supportive therapies that employ elevated oxygen concentrations, which put them at risk for developing pulmonary oxygen toxicity. This risk is made even greater by the immaturity of their cellular antioxidant defenses. Although the exact mechanisms of oxygen toxicity are still not fully defined, cellular damage is probably mediated by increased production of chemically reactive oxygen species (ROS) in the mitochondria. Cellular protection against ROS is provided by a variety of antioxidant molecules and enzymes, including the glutathione (GSH)-dependent antioxidant system. The GSH-dependent antioxidant enzyme system provides vital cellular protection against ROS, particularly hydrogen peroxide and certain organic hydroperoxides, under pathological and toxicological conditions, by using selenium-dependent and -independent peroxidases to reduce hydrogen peroxide or lipid peroxides to water or the respective alcohols, with the concurrent oxidation of GSH to glutathione disulfide (GSSG). In the mitochondria, limitations of GSH synthesis and transmembrane transport suggest that optimal functioning of the mitochondrial GSH system, and maintenance of adequate thiol-disulfide redox tone is essential to protect against the injurious effects of ROS. Manipulation of endogenous GSH concentrations can alter cellular responses to oxidant injury. Beneficial effects are evident when intracellular GSH concentrations are increased. In conditions that increase mitochondrial production of ROS, such as exposure to high concentrations of oxygen, therapies based on enhancing mitochondrial GSH concentrations could be highly beneficial.

Cardiac troponin: a new serum marker of myocardial injury in sepsis

OBJECTIVE

Echocardiogram-derived left ventricular ejection fraction (LVEF) is usually utilized to evaluate left ventricular function, including that of septic patients. However, LVEF is greatly influenced by afterload. The aim of this study was to test the hypothesis that troponin I, a serum marker of myocardial injury, may be able to detect left ventricular involvement by the septic process, being at least as sensitive an indicator of left ventricular dysfunction as LVEF in these patients.

DESIGN

Comparison of echocardiogram-derived LVEF with serum levels of troponin I in ten critically ill septic patients.

SETTING

General intensive care unit in a tertiary care private hospital.

PATIENTS

Ten critically ill septic patients with no previous documented heart disease.

MEASUREMENTS AND RESULTS

Patients were simultaneously submitted to a two-dimensional echocardiogram and troponin I determinations. LVEFs and troponin I levels were analyzed in a two-by-two table in order to validate troponin I as a new biochemical marker of myocardial injury in sepsis. All the patients whose LVEF was < 0.5 had elevated troponin I levels (kappa = 0.61, p = 0.035).

CONCLUSIONS

Identification of myocardial dysfunction in septic patients has been a challenging task. Troponin I, a serum marker of myocardial injury, may be of great help in the recognition of myocardial involvement by sepsis in a noninvasive and readily available way.

A national collaborative study of the in vitro activity of oral cephalosporins and loracarbef (LY 163892). Australian Group for the Study of Antimicrobial Resistance (AGAR)

A national collaborative study involving the laboratories of 17 Australian hospitals examined the in vitro activity of loracarbef, cefaclor, cephalexin, amoxycillin and amoxycillin/clavulanate against 2661 recently isolated common bacterial pathogens. Loracarbef was the most active agent against Escherichia coli (MIC90 = 1 mg/l) and had activity comparable to other agents against Klebsiella pneumoniae and Proteus mirabilis. Like the oral cephalosporins, it had no activity against species of Enterobacter and Serratia. beta-lactamase-producing Staphylococcus aureus and Haemophilus influenzae were moderately sensitive to loracarbef (MIC90 = 8 mg/l for both species). Streptococcus pneumoniae was moderately sensitive to loracarbef (MIC90 = 2 mg/l) but strains which were insensitive to penicillin were often highly resistant.

Multi-centre collaborative study for the in vitro evaluation of new macrolides dirithromycin and erythromycylamine. Australian Group for Antimicrobial Resistance (AGAR)

A national study was conducted to determine the in vitro activity of 2 newer macrolides, dirithromycin and erythromycylamine compared with that of erythromycin, tetracycline and penicillin. Nineteen major teaching hospitals participated in the study. Minimal Inhibitory Concentrations (MICs) were determined by agar dilution, mostly using Iso-Sensitest Agar and an inoculum of 10(4) cells per spot. 2284 clinically significant strains were isolated in late 1991 and early 1992, comprising 1736 Gram-positive cocci, 355 Haemophilus influenzae, 97 Moraxella catarrhalis, 32 Listeria monocytogenes, 25 Neisseria meningitidis and 39 Neisseria gonorrhoeae were tested. The study indicates that dirithromycin and erythromycylamine possess antibacterial activity equivalent to that of erythromycin against most Gram-positive cocci and M. catarrhalis. Strains resistant to erythromycin were also resistant to dirithromycin and to erythromycylamine. Tetracycline was as active as the macrolides against both penicillin-resistant and penicillin-susceptible strains of Staphylococcus aureus. Coagulase-negative penicillin-resistant staphylococci, compared with tetracycline, were relatively resistant to the macrolides. H. influenzae was less susceptible than the Gram-positive cocci.

Erythropoietin in very preterm infants

Three neonates (a male and two females of gestational ages 27, 27 and 29 weeks with birthweight 985, 660 and 1130 g), born to parents who are Jehovah's Witnesses, were admitted to our neonatal intensive care unit over a 2 month period in 1992. Human recombinant erythropoietin (rHuEpo, 200 u/kg sc. on alternate days for 6-8 weeks) was started early in conjunction with strict control of blood sampling in an attempt to avoid the need for blood transfusion. The lowest haemoglobin recorded was 95 g/L at 35 days of age in the first infant. The amount of blood withdrawn for sampling was 21.4 mL, 20.7 mL and 5.5 mL, respectively. All were discharged near their expected birthdate, never having received a blood transfusion in the Nursery. It is possible to manage sick, very preterm, very low birthweight neonates in a neonatal intensive care setting without the use of blood transfusions by the early use of rHuEpo in conjunction with strict control of blood sampling.

Clinical profile of severe birth asphyxia

In this retrospective analysis, 56 babies with Apgar score 3 and less were studied. In 33, successful bag-mask ventilation was carried out. Seventeen babies received endotracheal IPPV. In 9 out of them bag-mask ventilation was never tried whereas in 8 bag-mask ventilation had failed. In 6 babies physical stimulation and blast of oxygen on the face was adequate. Following this experience, in the subsequent years, endotracheal intubation was required mainly in extremely low birth weight babies or babies with Apgar score 0 at birth. During the study period, drugs were used in about 50% babies. In subsequent years this figure has come down to 10%, that too in special situations. This study helped us to evolve a policy in resuscitations severely asphyxiated babies. Bag-mask ventilation is the first choice. Failure to achieve progressively improving Apgar score by 1 minute, usually 4-5, is an indication for endotracheal intubation. Drugs are required in special situations only.

In vitro studies of ciprofloxacin and survey of resistance patterns in current isolates

We studied the activity of ciprofloxacin and other antibiotics against both routine and multiresistant (multi-R) clinical isolates. Ciprofloxacin inhibited more than 98% of most species of Enterobacteriaceae at a concentration of 2 micrograms/ml. Only Acinetobacter calcoaceticus, and to a much lesser degree, Providencia and Serratia, were resistant. Most Pseudomonas aeruginosa isolates were susceptible. Only 1% of staphylococci were resistant; the test panel included 1200 MRSA. For most species of streptococci, the MIC90 was 1 microgram/ml; for enterococci, it was 2 micrograms/ml. We also surveyed resistance in our current isolates. Resistance to ciprofloxacin has increased in A. calcoaceticus and Providencia, and in Streptococcus pneumoniae and group B streptococci. Ciprofloxacin-resistant isolates tended to show increased resistance to other antibiotics, including aminoglycosides and, later, cephalosporins.

Antibiotic resistance in Australia with special reference to sulbactam/ampicillin

A survey of antibiotic resistance in Australian states was undertaken by the Microbiology Quality Assurance Program of the Royal College of Pathologists of Australasia. Data were obtained from hospitals and private pathology laboratories serving both in-patients and out-patients at community hospitals. The study showed that resistance varied from state to state; it was highest in the Eastern states of New South Wales, Victoria, and Queensland, and lowest in Tasmania and Western Australia. In South Australia, isolates of Escherichia coli demonstrated a high degree of cefoxitin resistance. Western Australia and Tasmania showed high levels of gentamicin resistance for Klebsiella spp., as well as trimethoprim resistance in Proteus mirabilis. The relationship between erythromycin resistance and clindamycin resistance also differed among various states. These studies demonstrated the activity of sulbactam/ampicillin against a wide variety of common pathogenic bacteria in which resistance was mediated by beta-lactamase.

In vitro activity of A-56619 and A-56620 against multi-resistant and routine clinical isolates

A-56619 and A-56620 are two new quinolone compounds that are currently being studied. They were found to be active against multi-resistant and routine isolates of Staphylococcus aureus, enterobacteria, aminoglycoside-sensitive and resistant strains of Pseudomonas aeruginosa. Most of the enterobacteria were inhibited by 0.5-1 mg/l of A-56620. A-56619 was less active, concentrations of 1-4 mg/l being needed for 90% inhibition. Both the compounds were active at concentrations of 0.5-1 mg/l against staphylococci, including multi-resistant S. aureus. The MIC90 for P. aeruginosa was 1-2 mg/l for A-56620 and 8 mg/l for A-56619.

In vitro antibacterial activity of enoxacin (CI-919)

Antibacterial activity of enoxacin was evaluated against more than 3,700 clinical isolates using the agar-dilution method and an inoculum of 10(4)-10(5) cells per site. For comparison other antibiotics appropriate for each species were also included. For most enterobacteria and for Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa, the MIC90 of enoxacin was below 2 mg/l. Serratia marcescens was more resistant; the MIC90 being 4 mg/ml. Enoxacin also showed high activity against Campylobacter jejuni and Neisseria gonorrhoeae. Streptococci were comparatively resistant, 32 mg/l to 64 mg/l of the compound being required to inhibit 90% of strains.

Comparative antibacterial activities of new beta-lactam antibiotics against Pseudomonas aeruginosa

In vitro activity of nine new cephalosporins and penicillins was determined against 417 isolates of Pseudomonas aeruginosa. Carbenicillin, ticarcillin, gentamicin, tobramycin and netilmicin were also included in the study. Imipenem showed highest activity. More than 90% of the isolates were susceptible to ticarcillin, piperacillin, azlocillin, cefoperazone, cefsulodin and to tobramycin. 57 isolates included in the study were resistant to gentamicin (MIC greater than 4 mg/l); of these, none were resistant to imipenem, and more than 80% were susceptible to piperacillin, azlocillin, cefoperazone and cefsulodin.

A replicator method for the combined determination of minimum inhibitory concentration and minimum bactericidal concentration

Minimal bactericidal concentrations (MBCs) of nine antimicrobial agents were determined for clinical isolates by a replica plating method. Membranes were placed on the antibiotic-containing plates and the organisms replicated onto the membranes. After 18 h incubation the minimal inhibitory concentrations (MICs) were determined, the membranes were transferred to antibiotic-free plates and incubated a further 18 h and the MBCs determined. MICs and MBCs were also determined in broth. The reproducibility of the 'membrane' method and the agreement of these results for MIC and MBC with the agar and/or broth methods was satisfactory for most antibiotics, within one two-fold dilution. With sulphamethoxazole, trimethoprim and co-trimoxazole the results were less satisfactory, especially with Gram-negative rods, but agreement within two dilutions could be achieved.

An evaluation of recently developed antibiotics

A number of newer antibiotics, broad-spectrum penicillins and cephalosporins, have been evaluated against Gram-negative rods. The organisms were selected for multi-resistance and transferable resistance factors. None of the broad-spectrum penicillins was much use against most of the organisms. Ceftriaxone, cefotaxime, latamoxef (moxalactam) and N-formimidoyl thienamycin were all highly effective against most multi-resistant Gram-negative bacilli; cefoperazone being inferior to them. Enterobacter and Serratia strains were relatively resistant to all the agents mentioned and against Acinetobacter only N-formimidoyl thienamycin showed much activity. Thus, use of these drugs may increase the proportion of infections due to organisms such as Serratia or Acinetobacter.