Predictors of Invasive Herpes Simplex Virus Infection in Young Infants

OBJECTIVES

To identify independent predictors of and derive a risk score for invasive herpes simplex virus (HSV) infection.

METHODS

In this 23-center nested case-control study, we matched 149 infants with HSV to 1340 controls; all were ≤60 days old and had cerebrospinal fluid obtained within 24 hours of presentation or had HSV detected. The primary and secondary outcomes were invasive (disseminated or central nervous system) or any HSV infection, respectively.

RESULTS

Of all infants included, 90 (60.4%) had invasive and 59 (39.6%) had skin, eyes, and mouth disease. Predictors independently associated with invasive HSV included younger age (adjusted odds ratio [aOR]: 9.1 [95% confidence interval (CI): 3.4-24.5] <14 and 6.4 [95% CI: 2.3 to 17.8] 14-28 days, respectively, compared with >28 days), prematurity (aOR: 2.3, 95% CI: 1.1 to 5.1), seizure at home (aOR: 6.1, 95% CI: 2.3 to 16.4), ill appearance (aOR: 4.2, 95% CI: 2.0 to 8.4), abnormal triage temperature (aOR: 2.9, 95% CI: 1.6 to 5.3), vesicular rash (aOR: 54.8, (95% CI: 16.6 to 180.9), thrombocytopenia (aOR: 4.4, 95% CI: 1.6 to 12.4), and cerebrospinal fluid pleocytosis (aOR: 3.5, 95% CI: 1.2 to 10.0). These variables were transformed to derive the HSV risk score (point range 0-17). Infants with invasive HSV had a higher median score (6, interquartile range: 4-8) than those without invasive HSV (3, interquartile range: 1.5-4), with an area under the curve for invasive HSV disease of 0.85 (95% CI: 0.80-0.91). When using a cut-point of ≥3, the HSV risk score had a sensitivity of 95.6% (95% CI: 84.9% to 99.5%), specificity of 40.1% (95% CI: 36.8% to 43.6%), and positive likelihood ratio 1.60 (95% CI: 1.5 to 1.7) and negative likelihood ratio 0.11 (95% CI: 0.03 to 0.43).

CONCLUSIONS

A novel HSV risk score identified infants at extremely low risk for invasive HSV who may not require routine testing or empirical treatment.

Prevalence of healthcare-associated infections and antimicrobial use among inpatients in a tertiary hospital in Fiji: a point prevalence survey

Background

Healthcare-associated infections (HAIs) and antimicrobial use (AMU) are important drivers of antimicrobial resistance, yet there is minimal data from the Pacific region. We sought to determine the point prevalence of HAIs and AMU at Fiji’s largest hospital, the Colonial War Memorial Hospital (CWMH) in Suva. A secondary aim was to evaluate the performance of European Centre for Diseases Prevention and Control (ECDC) HAI criteria in a resource-limited setting.

Methods

We conducted a point prevalence survey of HAIs and AMU at CWMH in October 2019. Survey methodology was adapted from the ECDC protocol. To evaluate the suitability of ECDC HAI criteria in our setting, we augmented the survey to identify patients with a clinician diagnosis of a HAI where diagnostic testing criteria were not met. We also assessed infection prevention and control (IPC) infrastructure on each ward.

Results

We surveyed 343 patients, with median (interquartile range) age 30 years (16–53), predominantly admitted under obstetrics/gynaecology (94, 27.4%) or paediatrics (83, 24.2%). Thirty patients had one or more HAIs, a point prevalence of 8.7% (95% CI 6.0% to 12.3%). The most common HAIs were surgical site infections (n = 13), skin and soft tissue infections (7) and neonatal clinical sepsis (6). Two additional patients were identified with physician-diagnosed HAIs that failed to meet ECDC criteria due to insufficient investigations. 206 (60.1%) patients were receiving at least one antimicrobial. Of the 325 antimicrobial prescriptions, the most common agents were ampicillin (58/325, 17.8%), cloxacillin (55/325, 16.9%) and metronidazole (53/325, 16.3%). Use of broad-spectrum agents such as piperacillin/tazobactam (n = 6) and meropenem (1) was low. The majority of prescriptions for surgical prophylaxis were for more than 1 day (45/76, 59.2%). Although the number of handwashing basins throughout the hospital exceeded World Health Organization recommendations, availability of alcohol-based handrub was limited and most concentrated within high-risk wards.

Conclusions

The prevalence of HAIs in Fiji was similar to neighbouring high-income countries, but may have been reduced by the high proportion of paediatric and obstetrics patients, or by lower rates of inpatient investigations. AMU was very high, with duration of surgical prophylaxis an important target for future antimicrobial stewardship initiatives.

Association of a P2RX7 gene missense variant with brachycephalic dog breeds

Missense variants are associated with various phenotypic traits and disorders in dogs. The canine P2RX7 gene, coding the ATP-gated P2X7 receptor ion channel, contains four known missense variants. The current study aimed to examine the presence of these variants in a random sample of pedigree and mixed-pedigree dogs. Exons 3, 8, 11 and 13 of the P2RX7 gene, encoding these four respective variants, in 65 dogs were assessed by Sanger sequencing and combined with existing sequencing data from another 69 dogs. The distribution of these variants was then evaluated in all 134 dogs combined and separately within individual breeds including 35 different pure breeds. The rs23314713 (p.Phe103Leu) and rs23315462 (p.Pro452Ser) variants were present in 47 and 40% of all dogs studied respectively, with the rs23314713 variant associated with brachycephalic breeds. Among pedigree dogs, the rs23314713 and rs23315462 variants were associated with brachycephalic and non-brachycephalic breeds respectively. The rs851148233 (p.Arg270Cys) and rs850760787 (p.Arg365Gln) variants were present only in dogs of Cocker Spaniel and Labrador Retriever pedigrees respectively. No other missense variants were found in exons 3, 8, 11 and 13 of the P2RX7 gene within the dogs. In conclusion, the rs23314713 and rs23315462 missense variants of the P2RX7 gene are present in a large proportion of dogs, with the rs23314713 variant associated with a number of brachycephalic breeds. However, the association of this variant with dogs of bulldog ancestry, not brachycephaly per se, cannot be excluded.

Herpes Simplex Virus Infection in Infants Undergoing Meningitis Evaluation

BACKGROUND

Although neonatal herpes simplex virus (HSV) is a potentially devastating infection requiring prompt evaluation and treatment, large-scale assessments of the frequency in potentially infected infants have not been performed.

METHODS

We performed a retrospective cross-sectional study of infants ≤60 days old who had cerebrospinal fluid culture testing performed in 1 of 23 participating North American emergency departments. HSV infection was defined by a positive HSV polymerase chain reaction or viral culture. The primary outcome was the proportion of encounters in which HSV infection was identified. Secondary outcomes included frequency of central nervous system (CNS) and disseminated HSV, and HSV testing and treatment patterns.

RESULTS

Of 26 533 eligible encounters, 112 infants had HSV identified (0.42%, 95% confidence interval [CI]: 0.35%-0.51%). Of these, 90 (80.4%) occurred in weeks 1 to 4, 10 (8.9%) in weeks 5 to 6, and 12 (10.7%) in weeks 7 to 9. The median age of HSV-infected infants was 14 days (interquartile range: 9-24 days). HSV infection was more common in 0 to 28-day-old infants compared with 29- to 60-day-old infants (odds ratio 3.9; 95% CI: 2.4-6.2). Sixty-eight (0.26%, 95% CI: 0.21%-0.33%) had CNS or disseminated HSV. The proportion of infants tested for HSV (35%; range 14%-72%) and to whom acyclovir was administered (23%; range 4%-53%) varied widely across sites.

CONCLUSIONS

An HSV infection was uncommon in young infants evaluated for CNS infection, particularly in the second month of life. Evidence-based approaches to the evaluation for HSV in young infants are needed.

Reported practice variation in pediatric pain management: a survey of Canadian pediatric emergency physicians

OBJECTIVES

To describe pediatric emergency medicine (PEM) physicians' reported pain management practices across Canada and explore factors that facilitate or hinder pain management.

METHODS

This study was a prospective survey of Canadian pediatric emergency physicians. The Pediatric Emergency Research Canada physician database was used to identify participants, and a modified Dillman's Total Design Survey Method was used for recruitment.

RESULTS

The survey response rate was 68% (139 of 206). Most physicians were 31 to 50 years old (82%) with PEM training (56%) and had been in practice for less than 10 years (55%). Almost all pain screening in emergency departments (EDs) occurred at triage (97%). Twenty-four percent of physicians noted institutionally mandated pain score documentation. Ibuprofen and acetaminophen were commonly prescribed in the ED for mild to moderate pain (88% and 83%, respectively). Over half of urinary catheterizations (60%) and intravenous (53%) starts were performed without any analgesia. The most common nonpharmacologic interventions used for infants and children were pacifiers and distraction, respectively. Training background and gender of physicians affected the likelihood of using nonpharmacologic interventions. Physicians noted time restraints to be the greatest barrier to optimal pain management (55%) and desired improved access to pain medications (32%), better policies and procedures (30%), and further education (25%).

CONCLUSIONS

When analgesia was reported as provided, ibuprofen and acetaminophen were most commonly used. Both procedural and presenting pain remained suboptimally managed. There is a substantial evidence practice gap in children's ED pain management, highlighting the need for further knowledge translation strategies and policies to support optimal treatment.

Ultrasound or near-infrared vascular imaging to guide peripheral intravenous catheterization in children: a pragmatic randomized controlled trial

BACKGROUND

Peripheral intravenous catheterization in children is challenging, and success rates vary greatly. We conducted a pragmatic randomized controlled trial to determine whether the use of ultrasound or near-infrared vascular imaging to guide catheterization would be more effective than the standard approach in achieving successful catheter placement on the first attempt.

METHODS

We enrolled a convenience sample of 418 children in a pediatric emergency department who required peripheral intravenous catheterization between June 2010 to August 2012. We stratified them by age (≤ 3 yr and > 3 yr) and randomly assigned them to undergo the procedure with the standard approach, or with the help of either ultrasound or near-infrared vascular imaging. The primary outcome was the proportion of patients who had successful placement of a catheter on the first attempt.

RESULTS

The rate of successful first attempts did not differ significantly between either of the 2 intervention groups and the standard approach group (differences in proportions -3.9%, 95% confidence interval [CI] -14.2% to 6.5%, for ultrasound imaging; -8.7%, 95% CI -19.4% to 1.9%, for near-infrared imaging). Among children 3 years and younger, the difference in success rates relative to standard care was also not significant for ultrasound imaging (-9.6%, 95% CI -29.8% to 10.6%), but it was significantly worse for near-infrared imaging (-20.1%, 95% CI -40.1% to -0.2%). Among children older than 3 years, the differences in success rates relative to standard care were smaller but not significant (-2.3%, 95% CI -13.6% to 9.0%, for ultrasound imaging; -4.1%, 95% CI -15.7% to 7.5%, for near-infrared imaging). None of the pairwise comparisons were statistically significant in any of the outcomes.

INTERPRETATION

Neither technology improved first-attempt success rates of peripheral intravenous catheterization in children, even in the younger group. These findings do not support investment in these technologies for routine peripheral intravenous catheterization in children.

TRIAL REGISTRATION

ClinicalTrials.gov, no. NCT01133652.

Paediatric pain management practice and policies across Alberta emergency departments

BACKGROUND

Many children requiring acute care receive suboptimal analgesia.

OBJECTIVES

To describe paediatric pain management practices and policies in emergency departments (EDs) in Alberta.

METHODS

A descriptive survey was distributed to each of the EDs in Alberta.

RESULTS

A response rate of 67% (72 of 108) was obtained. Seventy-one percent (42 of 59) of EDs reported the use of a pain tool, 29.3% (17 of 58) reported mandatory pain documentation and 16.7% (10 of 60) had nurse-initiated pain protocols. Topical anesthetics were reported to be used for intravenous line insertion by 70.4% of respondents (38 of 54) and for lumbar puncture (LP) by 30.8% (12 of 39). According to respondents, infiltrated anesthetic was used for LP by 69.2% (27 of 39) of respondents, and oral sucrose was used infrequently for urinary catheterization (one of 46 [2.2%]), intravenous line insertion (zero of 54 [0%]) and LP (one of 39 [2.6%]).

CONCLUSIONS

Few Alberta EDs use policies and protocols to manage paediatric pain. Noninvasive methods to limit procedural pain are underutilized. Canadian paediatricians must advocate for improved analgesia to narrow this knowledge-to-practice gap.

Screening for post-traumatic stress disorder after injury in the pediatric emergency department--a systematic review protocol

BACKGROUND

Pediatric injury is highly prevalent and has significant impact both physically and emotionally. The majority of pediatric injuries are treated in emergency departments (EDs), where treatment of physical injuries is the main focus. In addition to physical trauma, children often experience significant psychological trauma, and the development of acute stress disorder (ASD) and post-traumatic stress disorder (PTSD) is common. The consequences of failing to recognize and treat children with ASD and PTSD are significant and extend into adulthood. Currently, screening guidelines to identify children at risk for developing these stress disorders are not evident in the pediatric emergency setting. The goal of this systematic review is to summarize evidence on the psychometric properties, diagnostic accuracy, and clinical utility of screening tools that identify or predict PTSD secondary to physical injury in children. Specific research objectives are to: (1) identify, describe, and critically evaluate instruments available to screen for PTSD in children; (2) review and synthesize the test-performance characteristics of these tools; and (3) describe the clinical utility of these tools with focus on ED suitability.

METHODS

Computerized databases including MEDLINE, EMBASE, CINAHL, ISI Web of Science and PsycINFO will be searched in addition to conference proceedings, textbooks, and contact with experts. Search terms will include MeSH headings (post-traumatic stress or acute stress), (pediatric or children) and diagnosis. All articles will be screened by title/abstract and articles identified as potentially relevant will be retrieved in full text and assessed by two independent reviewers. Quality assessment will be determined using the QUADAS-2 tool. Screening tool characteristics, including type of instrument, number of items, administration time and training administrators level, will be extracted as well as gold standard diagnostic reference properties and any quantitative diagnostic data (specificity, positive and negative likelihood/odds ratios) where appropriate.

DISCUSSION

Identifying screening tools to recognize children at risk of developing stress disorders following trauma is essential in guiding early treatment and minimizing long-term sequelae of childhood stress disorders. This review aims to identify such screening tools in efforts to improve routine stress disorder screening in the pediatric ED setting.

TRIALS REGISTRATION

PROSPERO registration: CRD42013004893.

Academic practice units and the School of Pharmacy, London

An independent report into pharmacy in Britain recommended that schools of pharmacy and hospitals should set up joint academic practice units to promote teaching and research. A number of such units have now been established in the south-east of England in association with the school of pharmacy, London university.

Stem cell biology in the lung and lung cancers: using pulmonary context and classic approaches

Classic stem cell biology approaches tailored specifically with lung biology in mind are needed to bring the field of lung stem cell biology up to speed with that in other tissues. The infrequent cellular turnover, the diversity of cell types, and the necessity of daily cell function in this organ must be considered in stem cell studies. Previous work has created a base from which to explore transplantation, label retention, and more sophisticated lineage-tracing schemes to identify and characterize stem cell populations in the normal lung. These approaches are also imperative for building on precedents set in other tissues in the exploration of the cancer stem cell hypothesis in lung cancers. Additionally, recent studies provide key leads to further explore the molecular mechanisms that regulate lung homeostasis. Here, we discuss strategies to advance the field of lung stem cell biology with an emphasis on developing new, lung-specific tools.

A randomized controlled trial of sucrose and/or pacifier as analgesia for infants receiving venipuncture in a pediatric emergency department

Background

Although sucrose has been accepted as an effective analgesic agent for procedural pain in neonates, previous studies are largely in the NICU population using the procedure of heel lance. This is the first report of the effect of sucrose, pacifier or the combination thereof for the procedural pain of venipuncture in infants in the pediatric emergency department population.

Methods

The study design was a double (sucrose) and single blind (pacifier), placebo-controlled randomized trial – factorial design carried out in a pediatric emergency department. The study population was infants, aged 0 – 6 months. Eighty-four patients were randomly assigned to one of four groups: a) sucrose b) sucrose & pacifier c) control d) control & pacifier. Each child received 2 ml of either 44% sucrose or sterile water, by mouth. The primary outcome measure: FLACC pain scale score change from baseline. Secondary outcome measures: crying time and heart rate change from baseline.

Results

Sucrose did not significantly reduce the FLACC score, crying time or heart rate. However sub-group analysis revealed that sucrose had a much greater effect in the younger groups. Pacifier use reduced FLACC score (not statistically significant), crying times (statistically significant) but not heart rate. Subgroup analysis revealed a mean crying time difference of 76.52 seconds (p < 0.0171) (0–1 month) and 123.9 seconds (p < 0.0029) (1–3 month). For subgroup age > 3 months pacifier did not have any significant effect on crying time. Age adjusted regression analysis revealed that both sucrose and pacifier had significant effects on crying time. Crying time increased with both increasing age and increasing gestational age.

Conclusion

Pacifiers are inexpensive, effective analgesics and are easy to use in the PED for venipuncture in infants aged 0–3 months. The benefits of sucrose alone as an analgesic require further investigation in the older infant, but sucrose does appear to provide additional benefit when used with a pacifier in this age group.

Trial registration

Current Controlled Trials ISRCTN15819627

Invasive group A streptococcal infection in injecting drug users and non-drug users in a single UK city

OBJECTIVES

Injecting drug users (IDU) represent an increasing proportion of patients with invasive group A streptococcal (GAS) disease. Our aims were to characterise the clinical presentation and strains causing GAS bacteremia in IDU from a single UK city (Brighton and Hove), and to compare this patient group with non-drug users (non-DU) with GAS bacteremia.

METHODS

Consecutive GAS blood culture isolates from twenty-two IDU and twenty-two non-DU presenting to the city hospital were studied. Clinical features, strain emm typing and superantigen toxin genotyping were investigated.

RESULTS

GAS invasive disease presented differently in IDU compared to non-DU with a predominance of injection site abscesses and lower mortality in IDU. GAS strains from IDU were predominantly emm82 and emm83 types, which are uncommon in the UK and emm82 strains appeared clonal. The non-DU GAS strains demonstrated a broader range of emm types including most frequently emm1 and emm89. There was no major difference in superantigen gene profile between the isolate groups.

CONCLUSION

The distinct presentation of invasive GAS disease in IDU compared with non-DU was associated with distinct emm types, a predominance of abscesses, and low mortality, although the small numbers preclude definitive conclusions. Further study is required to establish if these findings reflect strain differences or epidemiological differences in colonisation patterns and injecting practice.

Case of the month: Cutaneous myiasis in a returning traveller from the Algarve: first report of tumbu maggots, Cordylobia anthropophaga, acquired in Portugal

A 61 year old woman returning to the UK from the Algarve and complaining of boil-like lesions was found to have cutaneous myiasis caused by tumbu maggots, Cordylobia anthropophaga. This is apparently the first report of acquisition of this form of myiasis in Portugal.

Collisional studies of some C3H 7O (+) ions

The C3H7O(+) ions of nominal structures 1, 2, 3, and 4, produced by protonation of acetone, propanal, propylene oxide, and oxetan, respectively, have been studied by a variety of collisional techniques. The nominal isomers 2 and 3 give, within experimental error, identical high-energy collision-induced dissociation (CID) mass spectra. In addition, the breakdown graphs for the two isomers obtained from low, variable energy CID are identical, as are the neutrahzation-reionization mass spectra. The results are consistent with a facile isomerization of 3 to 2. By contrast, the ions of nominal structures 1 and 4 are shown by each technique to be distinct stable species in the gas phase. While the differences in the highenergy CID mass spectrum of 4 compared to 2 and 3 are relatively small, these differences are more pronounced in the low-energy CID mass spectra and become very large in the neutralization-reicnization mass spectra.

Haemoprotein b-590 (Escherichia coli); redesignation of a bacterial 'cytochrome a1'

A 'soluble' fraction from anaerobically grown Escherichia coli contains a haemoprotein with spectral properties, notably an alpha-band in the reduced form at 585 to 595 nm, similar to cytochrome a1. Haem extraction of either the soluble preparation or whole cells yields haem b, but not haem a. In view of this, and the spectral similarities of the a1-like component to well-known high-spin haem b proteins, we propose that the name 'haemoprotein b-590' be used to describe cytochrome a1-like pigments in bacteria.

Purification of penicillin-binding protein 2 of Escherichia coli

Penicillin-binding protein 2 (PBP-2) of Escherichia coli K-12 was purified by covalent affinity chromatography using 6-aminopenicillanic acid covalently coupled to carboxymethyl-Sepharose (6-APA-CM-Sepharose). Purification of PBP-2 was accomplished by prebinding the methoxy cephalosporin, cefoxitin, to the Triton X-100-solubilized PBPs of E. coli and then incubating the PBPs with 6-APA-CM-Sepharose. Cefoxitin readily binds to all the E. coli PBPs except PBP-2 and, thus, in the presence of cefoxitin, only PBP-2 could bind to the 6-APA-CM-Sepharose. The purification of a mixture of all of the PBPs of E. coli by affinity chromatography is also described.

Mutational evidence for identity of penicillin-binding protein 5 in Escherichia coli with the major D-alanine carboxypeptidase IA activity

The defect in D-alanine carboxypeptidase IA activity in the dacA11191 mutant of Escherichia coli was correlated with a defect in the release of penicillin G from penicillin-binding protein 5. The results suggest that penicillin-binding protein 5 catalyzes the major D-alanine carboxypeptidase IA activity of the wild type and that the mutation results in a defect in the deacylation step catalyzed by this enzyme.

Effects of sulfhydryl reagents on the binding and release of penicillin G by D-alanine carboxypeptidase IA of Escherichia coli

Purified D-alanine carboxypeptidase IA of Escherichia coli is inhibited by penicillin G and binds penicillin G reversibly. The binding of penicillin to the enzyme is relatively insensitive to sulfhydryl reagents, while release of penicillin from the enzyme is severely inhibited by these reagents. The inhibition of release parallels the inhibition of carboxypeptidase activity by the sulfhydryl reagents. In the presence of the sulfhydryl reagent p-chloromercuribenzoate, an acyl-enzyme intermediate, produced by the reaction of carboxypeptidase IA with diacetyl-L-lysyl-D-alanyl-D-alanine, accumulates and can be isolated. These results indicate that binding of penicillin to carboxypeptidase IA occurs by an acylation step of the carboxypeptidase reaction, while penicillin release occurs by a deacylation step of the reaction. Only the latter is inhibited by sulfhydryl reagents.

Involvement of the glucose enzymes II of the sugar phosphotransferase system in the regulation of adenylate cyclase by glucose in Escherichia coli

The nature of the interaction of glucose with toluene-treated cells of Escherichia coli leading to inhibition of adenylate cyclase was examined by the use of analogues. Those analogues with variations of the substituents about carbon atoms 1 or 2 (e.g. alpha-methylglucoside or 2-deoxyglucose) are inhibitory, and they are also substrates of the phosphoenolpyruvate-dependent sugar phosphotransferase system. Analogues with changes in other parts of the molecule (e.g. 3-O-methylglucose or galactose), L-glucose and several disaccharides and pentoses, do not inhibit adenylate cyclase and are not substrates of the phosphotransferase system. This correlation suggests some functional relationship between the adenylate cyclase and phosphotransferase systems. Further studies were done with mutants defective in glucose enzymes II of the phosphotransferase system (designated GPT and MPT); these two activities are measured by phosphorylation of alpha-methyl-glucoside and 2-deoxyglucose, respectively. The wild-type parent phosphorylates both analogues, and both inhibit adenylate cyclase. In the GPT- mutant, alpha-methylglucoside does not inhibit adenylate cyclase and is not phosphorylated, while 2-deoxyglucose is inhibitory and phosphorylated. In the GPT- MPT- double mutant, adenylate cyclase activity is present, but neither alpha-methylglucoside nor 2-deoxyglucose inhibits adenylate cyclase, and neither sugar is phosphorylated. These studies demonstrate that glucose inhibition of adenylate cyclase in toluene-treated cells requires an interaction of this sugar with either the GPT or mpt enzyme II of the phosphotransferase system.

Phosphorylation of D-glucose in Escherichia coli mutants defective in glucosephosphotransferase, mannosephosphotransferase, and glucokinase

Genetic studies show that Escherichia coli has three enzymes capable of phosphorylating glucose: soluble adenosine 5'-triphosphate-dependent glucokinase, which plays only a minor role in glucose metabolism; an enzyme II, called glucosephosphotransferase, with high specificity for the D-glucose configuration; and another enzyme II, called mannosephosphotransferase, with broader specificity. The former enzyme II is active on glucose and methyl-alpha-glucopyranoside, whereas the latter is active on D-glucose, D-mannose, 2-deoxy-D-glucose, D-glucosamine, and D-mannosamine. Mutations leading to loss of glucosephosphotransferase activity and designated by the symbol gpt are between the purB and pyrC markers in a locus previously called cat. The locus of mutations to loss of mannosephosphotransferase, mpt, is between the eda and fadD genes. Mutations to loss of glucokinase, glk, are between the ptsI and dsd genes.

Mechanism of energy coupling for transport of D-ribose in Escherichia coli

In Escherichia coli ML 308-225, d-ribose is transported into the cell by a constitutive active transport system of high activity. The activity of this transport system is severely reduced in cells subjected to osmotic shock, and the system is not present in membrane vesicles. The mechanism by which metabolic energy is coupled to transport of ribose was investigated. Substrates which generate adenosine 5'-triphosphate primarily through oxidative phosphorylation are poor energy sources for ribose uptake in DL-54, a mutant of ML 308-225 which lacks activity for the membrane-bound Ca(2+), Mg(2+)-dependent adenosine triphosphatase required for oxidative phosphorylation. Arsenate severely inhibits ribose uptake, whereas, under the same conditions, uptake of l-proline is relatively insensitive to arsenate. Anaerobiosis does not significantly inhibit ribose uptake in ML 308-225 or DL-54 when glucose is the energy source. A significant amount of ribose uptake is resistant to uncouplers of oxidative phosphorylation such as 2,4-dinitrophenol. These results indicate that the phosphate bond energy of adenosine 5'-triphosphate, rather than an energized membrane state, couples energy to ribose transport in ML 308-225.