Carriage Of Gram-negative Bacilli Research Articles

Rectal Carriage of Extended-Spectrum Beta-Lactamase and Carbapenemase Producing Gram-Negative Bacilli in Intensive Care Units in Tunisia

This study was conducted to evaluate the rate of fecal carriage of Gram-negative bacilli (GNB) resistant to third-generation cephalosporins (third GC) in patients hospitalized in the intensive care unit (ICU) of Charles Nicolle Hospital of Tunis and to identify the enzymatic mechanisms involved. From February to April 2014, rectal swabs were collected from all patients (n = 38) at admission and once weekly thereafter to identify acquisition. They were cultured on desoxycholate-lactose-agar plates supplemented with cefotaxime (2 mg/L). The rate of fecal carriage of GNB resistant to third GC was 0% (0/38) at admission and the acquisition rate was 45.16% (14/31). Nineteen GNB resistant to C3G were collected from 14 patients. The major species collected were Acinetobacter baumannii (n = 5), Klebsiella pneumoniae (n = 5), and Enterobacter cloacae (n = 5). Thirteen extended-spectrum β-lactamase (ESBL) producing GNB were found; CTX-M-15 (n = 10) and CTX-M-14 (n = 1) among Enterobacteriacae and GES-12 (n = 2) among A. baumannii. Ten strains were carbapenem resistant. OXA-48 (n = 4) and NDM-1 (n = 1) were detected among Enterobacteriacae and OXA-23 (n = 5), and GES-11 (n = 1) were detected in A. baumannii. Gene encoding the ACT-16 AmpC-type-β-lactamase was detected in two isolates. All Escherichia coli isolates were assigned to group B2. Among virulence genes, prevalence of fimH, fuyA, ompT, pai, and usp were highest observed in all E. coli isolates. Among K. pneumoniae mrkD and entB were the most frequent (n = 5) followed by ybtS (n = 4) and kfu (n = 2). This study revealed a high prevalence of fecal carriage of multidrug-resistant GNB, including ESBLs, carbapenemases, and cephalosporinases producing bacteria in patients hospitalized in ICU.

Carriage of gram-negative bacilli in young Brazilian children with community-acquired pneumonia

Background: Gram-negative bacilli are not infrequently encountered as etiologic organisms of pneumonia in children in warmclimate countries. Objectives: To investigate the nasopharyngeal carriage rate and antimicrobial susceptibility patterns of gram-negative bacilli colonizing children with community-acquired pneumonia in Fortaleza, Brazil. Methods: A single nasopharyngeal specimen was collected from children 2 months to 5 years of age presenting at one of the three children's hospitals in Fortaleza and fulfilling the World Health Organization criteria for pneumonia. Randomly recruited healthy children from public daycare centers and immunization clinics served as controls. Results: The study included 912 children, 482 (53%) with pneumonia and 430 (47%) controls. Aerobic gram-negative bacilli were seen in 79 (16%) of the 482 children with pneumonia and 51 (12%) of the 430 healthy controls. Nonfermentative gram-negative bacilli were seen in 85 (18%) of children with pneumonia and 54 (13%) of healthy controls. Neither gender, nutritional status, season, previous hospital admission nor antibiotic use was associated with carriage with gram-negative bacilli. However, pneumonia was associated with increased carriage, whereas concomitant colonization with Streptococcus pneumoniae or Haemophilus influenzae was associated with decreased carriage with gram-negative bacilli. Only 36% of all Escherichia species and 76% of all Klebsiella isolates were susceptible to cotrimoxazole; 90% of all Acinetobacter species were susceptible to gentamicin. Conclusion: Nasopharyngeal carriage with gram-negative bacilli, in particular with Acinetobacter species, is common and associated with a clinical diagnosis of community-acquired pneumonia in children in Fortaleza, Brazil.

Rational Approach to the Antibiotic Treatment of Pneumonia in the Elderly

The incidence of pneumonia is highest among the aged compared with other adult populations, and causes significant morbidity and mortality among this group. Most episodes of pneumonia are caused by aspiration of oropharyngeal flora into the lungs and failure of lung defence mechanisms to eliminate the aspirated bacteria. Studies in elderly patients have shown a high rate of oropharyngeal carriage of Gram-negative bacilli and polymicrobial/mixed flora pneumonias, especially in debilitated elderly patients in nursing homes or hospitals. This information is helpful to practitioners in prescribing empirical antibiotic therapy for elderly patients with pneumonia. Because of the many additional concerns which must be considered in the rational selection of an antibiotic regimen, e.g. route of administration, compliance, drug pharmacokinetics and pharmacodynamics, drug toxicity, and drug-disease interactions, it is also helpful for practitioners to become familiar with a small number of the large group of available antibiotics. Based on these considerations and the presumed bacteriology of pneumonia in the elderly in the 3 clinical settings (community, nursing home and hospital), a limited number of antibiotics are recommended for empirical antibiotic regimens for elderly patients with pneumonia. In particular, beta-lactamase inhibitors and cotrimoxazole (trimethoprim-sulfamethoxazole) are recommended, with ciprofloxacin as an alternative agent. There is a limited role for third-generation cephalosporins and extended-spectrum penicillins. Aminoglycosides are only recommended for patients with pneumonia in the intensive care unit on mechanical ventilation. Monotherapy (single agent) should be used whenever possible.

Selective decontamination of the digestive tract in the intensive care unit: current status and future prospects.

To evaluate the available data on selective decontamination of the digestive tract. This therapy aims to prevent infection in critically ill patients admitted to ICUs. Microbial carriage in the oropharynx, stomach, and gut; infection; mortality rate; and antibiotic resistance are the outcome events that are being reviewed. Published indices, abstract booklets, and conference proceedings up to the end of 1990. Sixteen controlled trials of selective decontamination were identified. None of these trials was conducted as a randomized, placebo-controlled, double-blind trial. Each of the three authors independently conducted a meta-analysis (thorough review) of the data from the 16 studies. Of the 16 trials, 15 show significant reduction of acquired infection among patients who received selective decontamination. Of the 14 studies that consider carriage of disease-causing microorganisms as an outcome event, 13 demonstrate a reduction in carriage of Gram-negative bacilli. Only ten studies consider mortality as an end-point, of which four demonstrate that the administration of selective decontamination is associated with decreased mortality rates in certain subgroups but not in the overall mortality rate. Of 11 studies that provide data about antibiotic resistance during selective decontamination, ten reported no increase in resistant microorganisms. Selective decontamination has been reported to be effective in controlling an outbreak of multi-resistant microorganisms. There is a general consensus about the efficacy of selective decontamination in diminishing microbial carriage and acquired infection rates, although conclusions about benefits related to mortality rates vary. Differences in mortality rate are found in the selective decontamination studies of patients with curable diseases, including multitrauma and cardiovascular patients. More data on resistance, collected over a longer period of time, are needed. Practical problems of blinding and the major ecological effect of selective decontamination may explain the lack of a randomized, placebo-controlled, double-blind trial.

Bacteria in a hospital nursery: laboratory and clinical studies.

SummaryTwo hundred and twenty-two infants and fifty-one staff were examined for carriage ofStaphylococcus pyogenesand Gram-negative bacilli, and the presence of these bacteria in the ward environment was also investigated. Staphylococci were phage-typed and tested for sensitivity to antibiotics. Assessment of clinical infection caused by these bacteria was made.Infant carriage ofStaphylococcus pyogeneswas maximal on the sixth day, 73·1 % of umbilical swabs yielding significant growth. Carriage of Gram-negative bacilli was maximal on the fifth day, 31·7% of umbilical swabs being positive. Where special nursing was enforced, i.e. premature baby unit, isolation of Gram-negative bacilli was very infrequent.The low nasal carriage of staphylococci seen in infants and nursing staff is attributed to traces of penicillinase-resistant penicillins in the ward air.Staphylococcus pyogeneswas recovered from 23 % of ward surfaces, and constituted 0·7% of the air-borne flora. In contrast, Gram-negative bacilli were recovered from 4·7 % of surfaces, and composed only 0·15% of the air-borne flora.Phage group I constituted 73·0, 44·9 and 41·2% of strains from infants, staff and ward environment respectively.Antibiograms were grouped into three categories, A, B and C. Category A (sensitive to chloramphenicol, erythromycin and methicillin but penicillin-resistant) composed 79·0% of infants' strains, being found mostly in group I, but was rare among staff strains.Of 54 specimens taken from 40 infants showing evidence of infection,Staphylococcus pyogeneswas isolated from 16, of which 14 were category A. Gram-negative bacilli were isolated 7 times. Only 21 infants required antibiotic therapy (9·3%) and none were infected with Gram-negative bacilli—this contrasts with the frequency of these bacilli in nursery infection today.Ward air is considered to be the maindepotofStaphylococcus pyogenes. Infant ‘dispersers’ are probably the principalsourceof the air-borne staphylococci. Infants and staff abstract from the air those staphylococci which become their colonizing strains. No transfer is thought to occur from the staff to the infants. Transmission of Gram-negative bacilli is similar in that the infants are the principal source and the air the maindepotof these bacteria. Nasal colonization by Gram-negative bacilli is low, this is possibly due to poor colonizing properties. Infant umbilical carriage almost certainly results from endogenous faecal spread.We are grateful to Dr J. C. Gould, Director, Central Microbiological Laboratories, Edinburgh, for his continued interest and advice, and to Mr J. C. Ferguson and Mrs M. M. Winton for skilled technical assistance. This study would not have been completed without the co-operation of Sisters McCartney and Struthers and their nursing staff.