Multilaboratory Comparison of Omadacycline MIC Test Strip to Broth Microdilution MIC against Gram-Negative, Gram-Positive, and Fastidious Bacteria.

The performance of the Liofilchem omadacycline MIC Test Strip (MTS) was evaluated in a multisite study. Three testing sites collected/tested clinical isolates and one site tested challenge isolates that totaled 175 S. aureus, 70 S. lugdunensis, 121 E. faecalis, 100 E. faecium, 578 Enterobacterales, 142 Haemophilus spp., 181 S. pneumoniae, 45 S. anginosus group, 35 S. pyogenes,and 20 S. agalactiae. MIC testing was performed by CLSI broth microdilution (BMD) and MTS. Fastidious isolates testing included BMD and MTS testing with both CLSI and EUCAST Mueller-Hinton Fastidious (MH-F). In addition, each site performed reproducibility for nonfastidious and fastidious isolates and QC by MTS and BMD. All BMD and MTS results for the QC strains were within expected ranges, with exception of one MTS HTM result for H. influenzae ATCC 49247. Among reproducibility isolates, omadacycline MTS results were within one dilution of the modal MIC for 95.2% of nonfastidious Gram-positive, 100% of Gram-negative, 99.3% and 98.5% of fastidious isolates tested on CLSI and EUCAST media, respectively. MTS results for all study isolates were within one doubling dilution of the CLSI BMD MIC for 98.9% of S. aureus, 100% of S. lugdunensis, 98.3% of E. faecalis, 100% of E. faecium, and 99.6% of Enterobacterales. Essential agreement rates for CLSI and EUCAST MH-F agar compared to CLSI BMD were 98.2% and 98.2%, for H. influenzae, 91.1% and 73.6%, for S. pneumoniae and 100% and 85-91.7% for other streptococcus species, respectively. Based on CLSI media, all categorical errors were minor errors and categorical agreement rates were >90% with exception of C. freundii, S. lugdunensis, E. faecalis, S. anginosus and S. constellatus.

Evaluation of the performance of DiaSorin molecular Pneumocystis jirovecii-CMV multiplex real-time PCR assay from bronchoalveolar lavage samples.

The aim of this study was to evaluate the performance of the DiaSorin Molecular PJ-CMV multiplex real-time PCR (PJ-CMV PCR) assay (DiaSorin Molecular LLC, USA) in bronchoalveolar lavage (BAL) samples compared to direct immunofluorescence assay (IFA) for the detection of Pneumocystis jirovecii and assess CMV and P. jirovecii co-infection rate in immunosuppressed patients with suspected pneumonia. A total of 125 BAL samples from immunosuppressed patients submitted for PJP-IFA were tested. Surplus samples were saved and further tested by using the PJ-CMV PCR assay. Among the 125 samples, P. jirovecii was detected in 31.2% (39/125) and in 40% (50/125) of the specimens using IFA and PJ-CMV PCR respectively. Eleven of the PJ-CMV PCR positive samples were negative by direct IFA for P. jirovecii. All samples positive by direct IFA were also positive by PJ-CMV PCR. Using the direct IFA as a gold standard, the PJ-CMV PCR sensitivity, specificity, positive predictive value and negative predictive value for detection of P. jirovecii were 100%, 87.2%, 78% and 100%, respectively. However, after reviewing the clinical diagnosis, the specificity and PPV increased to 100%. Of the 50 P. jirovecii samples positive by PJ-CMV PCR, 18 (36%) were also positive for CMV by the PJ-CMV PCR. The co-infection rate was found to be 37.5% (6/16) and 35.2% (12/34) in HIV infected and non-HIV infected patients. This study indicated that the DiaSorin Molecular PJ-CMV multiplex real-time PCR assay has higher sensitivity than direct IFA for detection of P. jirovecii and provides rapid detection of PJ and CMV infection in BAL samples.

Multilab evaluation of delafloxacin MIC Test Strip against Gram-negative and Gram-positive organisms.

The performance of the delafloxacin MIC Test Strip (MTS) was evaluated. Three testing sites collected/tested clinical isolates, and 1 site tested challenge isolates that together total 224 S. aureus, 36 S. haemolyticus, 23 S. lugdunensis, 105 E. faecalis, 308 Enterobacteriales, and 140 P. aeruginosa. MIC testing was performed by broth microdilution (BMD) and MTS. Each site also tested 20 common isolates in triplicate on 3 days by MTS and 20 replicates of 4 QC strains by MTS and BMD. MTS results for consolidated clinical/challenge isolates were within 1 doubling dilution of the BMD MIC for 96.9% of S. aureus; 100% of S. haemolyticus, S. lugdunensis, and E. faecalis; 98.4% of Enterobacteriales; and 97.9% of P. aeruginosa. All reproducibility results were within 1 dilution of the modal MIC. All BMD and MTS results for the QC strains were within expected ranges. Overall, the delafloxacin MTS performed similar to BMD.

Clinical and microbiological implications of time-to-positivity of blood cultures in patients with Gram-negative bacilli bacteremia.

Time-to-positivity (TTP) is defined as the length of time from the beginning of culture incubation to the detection of bacterial growth by an automated system. The objective of this study was to assess the clinical and microbiological implications of TTP among patients with Gram-negative bacilli (GNB) bacteremia. This was a prospective, single-center, observational study. Patients aged 18 years or older with one or more blood cultures growing GNB were included and followed until hospital discharge or death. Patients were excluded if they were without symptoms of infection, if they had polymicrobial culture, or if the culture was positive with an obligate anaerobe. A multivariate logistic regression analysis was performed to determine the predictors of in-hospital mortality, including TTP (primary endpoint), demographics, disease severity, comorbidities, pathogen type, source of infection, time to symptom resolution, hospital/intensive care unit (ICU) length of stay, adequacy of empiric antibiotics, and presence of an extended-spectrum beta-lactamase (ESBL)-producing bacteria. One hundred consecutive patients with GNB bacteremia were enrolled. TTP was an independent predictor of mortality; for every hour that TTP was shorter, the risk of mortality increased by 10% [odds ratio (OR) 1.10, 95% confidence interval (CI) 1.00-1.21, p = 0.049]. Other predictors of mortality included severity of illness, ESBL-producing GNB, and ICU admission within 24 h before culture. Mortality was highest among patients with inadequate empiric therapy (56% vs. 14%, p < 0.001) and TTP <11 h (23.1% vs. 8.3%, p = 0.18). Lactose-fermenting GNB had a shorter mean TTP than non-lactose fermenters (11.4 vs. 17.9 h, p = 0.001). Among patients with bacteremia due to GNB, TTP values are inversely associated with mortality risk.

Bordetella bronchiseptica in a paediatric cystic fibrosis patient: possible transmission from a household cat.

Bordetella bronchiseptica is a zoonotic respiratory pathogen commonly found in domesticated farm and companion animals, including dogs and cats. Here, we report isolation of B. bronchiseptica from a sputum sample of a cystic fibrosis patient recently exposed to a kitten with an acute respiratory illness. Genetic characterization of the isolate and comparison with other isolates of human or feline origin strongly suggest that the kitten was the source of infection.

Blood drawn through valved catheter hub connectors carries a significant risk of contamination.

Infection Control became concerned when bloodstream infection (BSI) rates increased after implementing a needleless valved hub connector. During a 21-month period three different needleless catheter hub connectors were evaluated by quantitatively culturing blood drawn through hub connectors that would have ordinarily been discarded (DBC). DBC drawn through Clearlink™ catheter hub connectors were found to be twice as likely to be positive as DBC drawn through Clave® or Q-syte™ hub connectors (P < 0.04). DBC grew pathogens 46% of the time and skin organisms 54% of the time. Patients with positive DBC were three times more likely to meet Centers for Disease Control (CDC) BSI criteria by DBC cultures than by physician-ordered blood cultures (CBC; P < 0.001). For patients growing pathogens in DBC, 64% had no CBC drawn, the average temperature was lower than for patients with pathogens in CBC (99.3 ± 1.5 ve 100.6 ± 1.9, P = 0.015), and 92% of discharged patients (11 out of 12) were not treated with an antibiotic active against the DBC pathogen. Drawing BC through a catheter hub connector carries a risk of false-positives that could increase BSI rates by up to 3-fold. Further work is necessary to evaluate this concern.

Susceptibilidad antifúngica de Candida albicans recuperadas de pacientes con SIDA y candidiasis orofaríngea y esofágica. Experiencia con Etest / Antifungal susceptibility for Candida albicans isolated from AIDS patients with oropharyngeal and esophageal candidiasis: experience with Etest

BACKGROUND: Oropharyngeal candidiasis (OPC) and esophageal candidiasis (EPC) are frequent complications in AIDS patients. The use of Fluconazole, an effective and a low toxicity drug, has been associated to the emergency of secondary resistant strains. For this reason, in vitro antifungal susceptibility tests are necessary to predict a therapeutic failure. Etest is an easy to perform alternative test, that has showed a good agreement with the broth microdilution reference method (NCCLS, document M27-A). AIM: To measure the susceptibility of C. albicans isolates from AIDS patients complicated with OPC and EPC to Amphotericin B (AmB) and Fluconazole (Flu) using Etest. MATERIAL AND METHODS: Twenty strains from 20 AIDS patients were studied. AmB was tested in RPMI 1640 agar and Flu in Casitone agar. RESULTS: All studied strains showed minimal inhibitory concentrations (MICs) < 1 mg/mL for AmB. A highly resistant strain to Flu (> 256 mg/mL) was isolated from a patient previously treated with Flu. CONCLUSIONS: In AIDS patients with OPC and EPC, the susceptibility to Flu of the isolates should be screened, to detect resistant strains. Etest is a reliable alternative in these cases, for laboratories that cannot use the reference method.

Prevalence of beta-lactamase production in H. influenzae isolated in Latin America in 1998-1999: results of the LASER study.

The objective of this study was to assess the prevalence of beta-lactamase production in Haemophilus influenzae clinical isolates obtained throughout Latin America and the West Indies in 1998-1999. Isolates were collected from 15 centres (seven countries), identified by standard methods and grouped by patient age. The overall prevalence of beta-lactamase production was 17.8% (270/1513 isolates). The prevalence of beta-lactamase positive strains varied between countries, with the highest prevalence detected in Panama (23.4%, 29/124) and the lowest in the West Indies (10.5%, 4/38). beta-Lactamase-positive strains were more frequently isolated from children aged < or =3 years (22.0%) and from adults aged > or =65 years (26.5%). The high prevalence of beta-lactamase production found should be considered when choosing empirical antibiotic therapy where H. influenzae is suspected.

Activities of a new fluoroketolide, HMR 3787, and its (des)-fluor derivative RU 64399 compared to those of telithromycin, erythromycin A, azithromycin, clarithromycin, and clindamycin against macrolide-susceptible or -resistant Streptococcus pneumoniae and S. pyogenes.

Activities of HMR 3787 and RU 64399 were compared to those of three macrolides, telithromycin, and clindamycin against 175 Streptococcus pneumoniae isolates and 121 Streptococcus pyogenes isolates. HMR3787 and telithromycin were the most active compounds tested against pneumococci. Telithromycin and RU 64399 were equally active against macrolide-susceptible (MICs, 0.008 to 0.06 microg/ml) and -resistant S. pyogenes isolates, but HMR 3787 had lower MICs for ermB strains.

The crisis of resistant pathogens in respiratory tract infections--use of pharmacodynamic principles.

Infectious disease experts and public health officials continue to warn the medical community and the public that more strains of respiratory tract pathogens are becoming resistant to the antibiotics commonly used to eradicate them. The inappropriate use of antibiotics to treat viral infections has contributed to the development of multidrug resistance in the 3 key bacterial pathogens that cause respiratory tract infections: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Traditionally, susceptibility of pathogens to antibiotics has been evaluated with in vitro testing by minimum inhibitory concentration (MIC) determination, which has also been used to establish breakpoints between susceptible and resistant organisms based on MIC distributions. However, a more clinical approach has been developed based on the correlation of pharmacokinetics (PK) and pharmacodynamics (PD) of antimicrobials with MICs and clinical studies, thereby establishing the new concept of PK/PD breakpoints. New guidelines for outpatient management of respiratory tract infections have been based on PD parameters.

High prevalence of carriage of antibiotic-resistant Streptococcus pneumoniae in children in Kampala Uganda.

There are few data on antibiotic-resistant Streptococcus pneumoniae in Uganda. A total of 191 healthy children in Kampala, Uganda were screened for nasopharyngeal carriage of S. pneumoniae; 118 (62%) of the children were carriers. Antimicrobial susceptibility and serotype of 115 strains was determined. Ninety-six (83.5%) of the isolates were of intermediate resistance to penicillin and 19 (16.5%) were susceptible. All strains were susceptible to cefotaxime. The rates of resistance to other drugs were trimethoprim-sulphamethoxazole (83.5%), tetracycline (28.7%) and chloramphenicol (10.4%). All strains were susceptible to rifampicin, erythromycin and clindamycin. Serogroups 6, 9, 14, 19 and 23 accounted for 80% of the isolates. These data show that the rate of carriage of antibiotic-resistant pneumococci by children is high in Kampala, Uganda.

Prevalence and mechanisms of macrolide resistance in Streptococcus pyogenes in Santiago, Chile.

Thirty-two macrolide-resistant Streptococcus pyogenes isolates were found among 594 clinical isolates collected from 1990 to 1998 in Santiago, Chile, for an overall prevalence of 7.2%. Among the 32 resistant isolates, 28 (87.5%) presented the M phenotype and 4 (12. 5%) presented the MLS(B) phenotype. Serotyping and pulsed-field gel electrophoresis analysis showed genetic diversity among the resistant isolates.

HLA and celiac disease in Argentina: involvement of the DQ subregion.

A population of 62 unrelated homogeneous Argentinian celiac pediatric patients were typed for HLA-A,B,C,DR, and DQ antigens. The association between celiac disease and the DR3 and DR7 antigens was confirmed. The specificity DQw2 was present in 95.2 per cent of the patients. Nevertheless, it was of interest that the most significant phenotypes observed were DR3/DR7, DR7/DR5, and DR3/DR5. The significance of these findings is discussed.

Restriction fragment length polymorphism in HLA class II genes of Latin-American Caucasian celiac disease patients.

In the present study Latin-American celiac disease patients were analyzed for the frequency of certain HLA class II restriction fragment length polymorphisms in order to investigate whether they exhibited the normal associated alleles or showed unusual class II variants. A DPB/RsaI 4.0-kb fragment that was shown to be significantly increased among North Americans celiac disease patients of the DR3,DQw2 haplotype was found with similar frequency in Latin-American control and celiac disease individuals. A DPA/BglII 3.7-kb fragment previously shown to be increased among British celiac disease patients was also present with similar frequency among Latin-American control and celiac disease individuals. These results show that the frequency of the HLA-DP region-derived restriction fragment length polymorphisms linked to celiac disease differs between Caucasian populations of different ethnic backgrounds (Anglo-Saxon and Latin-American). On the other hand, DNA samples from 13 patients and 14 controls bearing the DR5/DR7 phenotype (which is significantly associated with celiac disease in Latin populations) were investigated for the presence of particular restriction fragment length polymorphisms disproportionally present in celiac disease individuals. No significant differences were found between controls and patients when the DNA was analyzed with 10 different restriction enzymes and probes for DRB, DQA, DQB, and DPB HLA class II sequences.

[HLA and disease in Argentina. Serologic and genomic polymorphism]. / HLA y enfermedad en la Argentina. Polimorfismo serológico y genómico.

In this report we discuss the results of the association of chronic active hepatitis (B virus) and coeliac disease with HLA class I and class II antigens, in patients of Latin American Caucasian origin. Evidence is presented showing that the alleles involved differ from those reported in other Caucasian populations of different ethnic background. Differences were observed both at the serology and at the DNA (RFLP) level. The relevance of these findings regarding the clinical implications as well as the molecular mechanisms involved in the associations are discussed.

HLA y enfermedad en la Argentina: polimorfismo serológico y genómico / HLA and disease in Argentina: serological and genomic polymorphism

En este trabajo se describen los resultados de dos estudios de asociación de patologías a determinados alelos de clase I y clase II del sistema HLA en pacientes caucásicos argentinos: la hepatitis crónica activa (virus B) y la enfermedad celíaca. Se presentan evidencias que muestran para ambas patologías que los alelos HLA involucrados no son los mismos que los hallados para otros grupos éticos. Estas diferencias residen tanto a nivel serológico como a nivel del DNA (evaluable por RFLP). Estos hallazgos son relevantes tanto en lo referente a las aplicaciones clínicas de las asociaciones descriptas (por ejemplo la tipificación de hermanos o hijos de pacientes celíacos para identificar a los portadores de los alelos de riesgo), como así también para invetigar las bases moleculares de las maismas (AU)