Re-exploring the value of surveillance cultures in predicting pathogens of late onset neonatal sepsis in a tertiary care hospital in southern Sri Lanka.

OBJECTIVE: To identify the validity of surveillance cultures in predicting causative organism(s) of late onset neonatal sepsis. RESULTS: Prospective analytical study was conducted from January to April 2011 at the Neonatal Intensive Care Unit, Teaching Hospital, Karapitiya, Galle, Sri Lanka. Fifty neonates were screened on admission and weekly thereafter for colonization with potential pathogens. On suspicion of infection, relevant samples were cultured and tested for antibiotic sensitivity. There were 55 episodes of clinically suspected infections including 33 nosocomial infections. One-third (17/55) of all clinically suspected infections were culture positive. Out of 55, only 33 episodes were clinically suspected nosocomial infections. Clinically suspected nosocomial infection rate was 50/1000 patient-days. Culture proven nosocomial infection rate was 13.61/1000 patient-days. Coliforms were the commonest clinical isolate (76%) and 2/3 of them produced extended spectrum ß lactamase. More than 80% of the isolates causing late onset sepsis were sensitive to carbapenems and aminoglycosides. Sensitivity, specificity, positive predictive value and negative predictive value of surveillance cultures were 77.8, 37.5, 31.8 and 81.8%, respectively. Surveillance samples can be used to predict pathogens of late-onset sepsis. Broad-spectrum antibiotics (carbapenems, aminoglycosides) are recommended as empirical therapy for late-onset neonatal sepsis.

Applications of novel direct bioautography tests for analysis of antimicrobials: a review.

TLC coupled to direct bioautography detection can be applied to the analysis of various antimicrobial agents in complex matrixes. Because of the lack of commercially available microbiological detection methods, two direct bioautography tests were developed in our laboratory to be used after TLC separation. One method was based on Gram-positive bacteria, Bacillus subtilis, and the other on Gram-negative bacteria, Escherichia coli. These tests can be used for detection and determination of wide spectrum of antimicrobials as well as for other, nontypical purposes, such as choosing the best sample preparation method before the analysis. Some of the more interesting applications of the newly developed tests are described in this paper.

Daptomycin Etest MICs for methicillin-resistant Staphylococcus aureus vary among different media.

For optimum activity of daptomycin (DAP) in vitro, medium supplemented with calcium ions at physiological concentration (i.e., 50 mg/l) is required for determination of DAP minimum inhibitory concentration (MIC) in the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) method. However, our literature review found that Mueller-Hinton agar (MHA) brands used for the DAP Etest had different calcium ion (Ca²âº) concentrations among the reports. For 98 clinical methicillin-resistant Staphylococcus aureus isolates previously unexposed to DAP, MICs were assessed by use of the Etest with MHA plates with different media (MHA-A, MHA-B, and MHA-C) and compared with those from the CLSI reference BMD method. The instructions for the Etest recommend MHA with Ca²âº of 25-40 mg/l for DAP MIC testing; Ca²âº concentrations for each type of MHA were 20.4 mg/l in MHA-A, 45.2 mg/l in MHA-B, and 52.0 mg/l in MHA-C. When the MIC50/MIC90 of the clinical isolates were studied, the Etest MICs for MHA-A were 1-fold dilution higher than for the BMD value. In contrast, for MHA-B they were 1-fold dilution lower, and for MHA-C MIC50 was 1.5-fold dilution lower and MIC90 was 2-fold dilution lower. MICs measured in MHA with higher Ca²âº tended to be lower. Comparison of MICs between BMD and the Etest for each MHA showed they were significantly different (p < 0.0001). The correlation coefficient was 0.6258 (p < 0.0001) for MHA-A, 0.4224 (p < 0.0001) for MHA-B, and 0.2504 (p = 0.0129) for MHA-C. Our results suggest there are differences in DAP MICs between MIC testing methods and differences between Ca²âº concentrations in MHA. For more objective and accurate measurement of DAP MICs, there should be discussion about standardization of Ca²âº in MHA.

Certification of TB culture and drug susceptibility testing laboratories through the Revised National Tuberculosis Control Programme (RNTCP).

The RNTCP is implementing the Programmatic Management of Drug Resistant Tuberculosis (PMDT) for detecting and treating drug resistant tuberculosis (DR-TB). Diagnostic services for DR-TB is provided through a network of RNTCP certified Culture and Drug Susceptibility Testing (C&DST) laboratories.This paper describes about the process involved in certification of C&DST laboratories for different technologies used in RNTCP.

[Central inter-laboratory quality control for microscopic diagnosis of tuberculosis in Madagascar in 2000]. / Contrôle de qualité inter-laboratoires centraux pour le diagnostic microscopique de la tuberculose à Madagascar en 2000.

Since June 1997, a quarterly quality control of sputum smear exam for the tubercle diagnosis, depending on double reading of slides, was implemented between both central laboratories of the Mycobacteria National Reference Centre in Madagascar (mycobactoria laboratories of Institut Pasteur Madagascar [IPM] and Institut Hygiène Sociale [IHS]--Health Ministry). In 2000, four controls were done, in the course of which 240 slides were coloured by auramine, coming both from IPM and IHS, and another 80 slides from IHS were coloured by Ziehl-Neelsen. All the results were in agreement for the samples stained with auramine, while two false negatives were found for the samples stained with Ziehl-Neelsen. The maintenance of this quality control between the two laboratories is necessary to insure the reliability of their results and the controls that they make for the peripheral laboratories.

Eficacia de la monoterapia con piperacilina/tazobactám en infecciones de piel y partes blandas / Effectiveness of monotherapy with piperacillin/tazobactam in skin and soft tissue infections

Introducción. Se evaluaron la eficacia clínica por intención de tratar y la seguridad de piperacilina/tazobactám (monoterapia) en las infecciones de piel y partes blandas, así como los efectos secundarios ocasionados por dicho fármaco. Pacientes y métodos. Se realizó un estudio multicéntrico, prospectivo, observacional, en el que se incluyeron 160 pacientes con infección de piel y partes blandas, procedentes de los 15 centros participantes. Tras estandarizar los criterios diagnósticos, los pacientes fueron sometidos al protocolo de inclusión y se administró el fármaco indicado, por vía intravenosa, a dosis de 4/0,5 g cada 8 h. Se realizó control bacteriológico al inicio y al final del tratamiento. Resultados. La edad media de los pacientes fue de 57,3 años, con un porcentaje de varones afectados del 60,7 por ciento. La mayor parte de las infecciones fueron extrahospitalarias, y la diabetes fue el factor predisponente en más de la mitad de casos. El 43,8 por ciento de los procesos fue catalogado como grave. Se aisló el microorganismo responsable de la infección en el 59,3 por ciento de los casos, siendo la mayor parte monomicrobianas. Se suspendió el protocolo en 18 casos (11,2 por ciento) y aparecieron 8 casos de reacciones adversas relacionadas con el fármaco. La evaluación clínica indicó una respuesta favorable del 88,8 por ciento a la monoterapia con piperacilina/tazobactám, y la erradicación o presunta erradicación bacteriana alcanzó el 63,8 por ciento de pacientes. Conclusiones. En nuestra experiencia, la eficacia de piperacilina/tazobactám permite utilizar este antibiótico de forma empírica en monoterapia en infecciones graves de piel y partes blandas (AU)

Laboratory diagnosis and oral treatment of CAPD peritonitis.

The laboratory diagnosis of 50 consecutive episodes of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was studied. The technique which yielded the highest rate (84%) of positive bacteriological diagnoses was inoculation and subculture of thioglycollate broth. Cloudiness of fluid to the naked eye was an accurate predictor of a raised white cell count. A minimum laboratory protocol for the bacteriological diagnosis of CAPD peritonitis was devised and has been in use satisfactorily since the completion of the study. Antibiotic treatment was given orally in the first instance in 43 episodes and was successful in 34.

Factors influencing detection of salmonellae in rendered animal by-products.

Detection of salmonellae in animal by-products is influenced by the enrichment and plating media and by quantity of product tested, and is related to the total plate count. A linear relationship exists between detection of salmonellae and total plate counts from 10(4) through 10(7) per gram.

Interfering effect of incubation in carbon dioxide on the identification of pneumococci by optochin discs.

Incubation of pneumococci in a CO(2) environment decreases the zone sizes produced by optochin discs, with the result that pneumococcal-like organisms require further study.

Anaerobic roll tube media for nonselective enumeration and isolation of bacteria in human feces.

Medium 10 (M10), developed for rumen bacteria and containing small amounts of sugars, starch, volatile fatty acids, hemin, Trypticase, yeast extract, cysteine, and sulfide, plus agar, minerals and CO(2)-HCO(3)-buffer, was used with the Hungate anaerobic method as a basal medium to evaluate the efficacy of various ingredients. Three-day-old colony counts from adults on normal diets (17 samples) were 0.55 x 10(11) to 1.7 x 10(11) per g (mean, 1.15 x 10(11)) for M10. Single deletion of volatile fatty acids, Trypticase, yeast extract, or sulfide did not reduce counts. Deletion of hemin or both Trypticase and yeast extract significantly lowered counts. Addition of fecal extract, rumen fluid, 1% dehydrated Brain Heart Infusion (BHI) or 2 to 6% liver infusion did not increase counts; 1% dehydrated bile or 3.7% BHI markedly depressed them. Decreasing the gas-phase CO(2) concentration from 100 to 5% with N(2) and correspondingly lowering the HCO(3) had little effect. Counts in supplemented Brewer Thioglycollate (Difco), BHI, and Trypticase soy agar were similar or lower than in M10; ease in counting was best in M10. Comparison of features of 88 predominant strains of fecal bacteria randomly isolated indicated that M10 supported growth of as many or more species of bacteria as compared to supplemented BHI. The results suggest that predominant bacteria of human feces, in general, are not as nutritionally fastidious as rumen bacteria and indicate that media for counts or isolation containing large amounts of rich organic materials are neither necessary nor desirable when adequate anaerobic techniques are used.

Comparison of Schaedler agar and trypticase soy-yeast extract agar for the cultivation of anaerobic bacteria.

Schaedler agar (SA) and Trypticase soy-yeast extract agar (TSYEA), both supplemented with rabbit blood (5%, v/v) and menadione (0.5 mg/liter), were compared with respect to quantitative recovery, quality of growth, and rapidity of growth of selected anaerobic bacteria. The media were stored for 2 to 4 days prior to use in an anaerobic glove box, where all subsequent bacteriological procedures were performed. After 24 hr of incubation, colonies of Clostridium cadaveris (C. capitovale), C. haemolyticum, C. novyi A, and C. perfringens were larger on SA than on TSYEA, and the appearance of C. novyi B colonies on SA at 24 hr antedated their appearance on TSYEA. Quantitative recovery of C. novyi B was improved on SA; recovery of the other clostridia tested was comparable on the two media (inconclusive results were obtained with C. novyi A). Rough colonial types of some of the clostridia emerged on SA. No appreciable differences in results with the two media were noted for Bacteroides fragilis, B. melaninogenicus, or Fusobacterium fusiforme.