Systems approach to improving antimicrobial susceptibility testing in clinical laboratories in the United States

Phytochemical analysis and biological activities of essential oils extracted from Origanum grossii and Thymus pallidus: in vitro and in silico analysis

The study aimed at investigating the phytochemical composition, antioxidant and antibacterial activities of essential oils (EOs) of Origanum grossii and Thymus pallidus. The selection of these plants for the study was driven by a comprehensive survey conducted in the Ribat Elkheir region of Morocco, where these plants are widely utilized. The results reflect the valorization of these plants based on the findings of the regional survey. The GC-MS phytochemical analysis revealed that the main constituents of the essential oil were carvacrol and thymol for O. grossii and T. pallidus respectively. Quantitative assays demonstrated that O. grossii exhibited higher levels of polyphenols (0.136 mg AGE/mg EO) and flavonoids (0.207 mg QE/mg EO) compared to T. pallidus. The DPPH assay indicated that O. grossii EOs possessed approximately twice the antiradical activity of T. pallidus, with IC50 values of approximately 0.073 mg/mL and 0.131 mg/mL, respectively. The antibacterial activity tests showed that both essential oils exhibited significant inhibition zones ranging from 26 to 42 mm against all tested bacterial strains. The MIC values varied among the bacteria, generally falling within the range of 0.31 to 2.44 µg/mL, demonstrating the potency of the EOs to serve as antibacterial. Molecular docking revealed that O. grossii and T. pallidus essential oils interact with antibacterial and antioxidant proteins (1AJ6 and 6QME). Key compounds in O. grossii include p-cymene, eucalyptol, and carvacrol, while T. pallidus contains potent chemicals like p-cymene, ɤ-maaliene, valencene, α-terpinene, caryophyllene, himachalene, and thymol. Notably, the most potent chemicals in Origanum grossii are p-cymene, eucalyptol, and carvacrol, while the most potent chemicals in Thymus pallidus are p-cymene, α-terpinene, and thymol. These findings suggest that these plant EOs could be used to develop new natural products with antibacterial and antioxidant activity.

Surveillance of Gram-negative bacteria: impact of variation in current European laboratory reporting practice on apparent multidrug resistance prevalence in paediatric bloodstream isolates

This study evaluates whether estimated multidrug resistance (MDR) levels are dependent on the design of the surveillance system when using routine microbiological data. We used antimicrobial resistance data from the Antibiotic Resistance and Prescribing in European Children (ARPEC) project. The MDR status of bloodstream isolates of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa was defined using European Centre for Disease Prevention and Control (ECDC)-endorsed standardised algorithms (non-susceptible to at least one agent in three or more antibiotic classes). Assessment of MDR status was based on specified combinations of antibiotic classes reportable as part of routine surveillance activities. The agreement between MDR status and resistance to specific pathogen-antibiotic class combinations (PACCs) was assessed. Based on all available antibiotic susceptibility testing, the proportion of MDR isolates was 31% for E. coli, 30% for K. pneumoniae and 28% for P. aeruginosa isolates. These proportions fell to 9, 14 and 25%, respectively, when based only on classes collected by current ECDC surveillance methods. Resistance percentages for specific PACCs were lower compared with MDR percentages, except for P. aeruginosa. Accordingly, MDR detection based on these had low sensitivity for E. coli (2-41%) and K. pneumoniae (21-85%). Estimates of MDR percentages for Gram-negative bacteria are strongly influenced by the antibiotic classes reported. When a complete set of results requested by the algorithm is not available, inclusion of classes frequently tested as part of routine clinical care greatly improves the detection of MDR. Resistance to individual PACCs should not be considered reflective of MDR percentages in Enterobacteriaceae.

Postoperative nosocomial infections among children with congenital heart disease

OBJECTIVE

To study the pathogen distribution, antimicrobial susceptibility and risk factors of postoperative nosocomial infections among children with congenital heart disease.

METHODS

Three hundreds children with congenital heart disease admitted to our hospital to receive surgeries from February 2010 to February 2013 were selected.

RESULTS

A total of 120 children were tested as positive by sputum culture, with the infection rate of 40.0%. The top five most common pathogenic microorganisms included Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus, Pseudomonas aeruginosa, and Candida albicans. S. epidermidis, S. aureus and Enterococcus were highly resistant to penicillin, azithromycin and erythromycin, moderately susceptible to levofloxacin and cefazolin, and completely susceptible to vancomycin. Multivariate Logistic regression analysis showed that hospitalization stay length, combined use of antibiotics, systemic use of hormones, mechanical ventilation and catheter indwelling were the independent risk factors of postoperative nosocomial infections (P<0.05).

CONCLUSION

Nosocomial infection, which was the most frequent postoperative complication of pediatric congenital heart disease, was predominantly induced by Gram-positive bacteria that were highly susceptible to cephalosporins and vancomycin. Particular attention should be paid to decrease relevant risk factors to improve the prognosis.

Origins and development of the National Laboratory System for public health testing

Although not recognized as such, a National Laboratory System (NLS) has existed since the inception of public health laboratory (PHL) testing more than a century ago. The NLS has always relied upon the participation of clinical laboratories, both to report test results that represent public health threats and to submit specimens and isolates to PHLs for additional or confirmatory testing. Historically, a number of factors have hindered the strengthening of the relationships between clinical laboratories and PHLs, but the reality of bioterrorism and subsequent focus on strengthening public-private relationships has stimulated the development of a more robust NLS. Since 2002, there has been substantial strengthening of the NLS through the sharing of lessons learned from several demonstration projects. There is a growing emphasis on defining critical elements of the NLS, including the State Public Health Laboratory System (SPH Laboratory System) and the functions of the Laboratory Program Advisor, a position that every state should have at the center of its laboratory system's capacity-building. Additional strengthening of the NLS is occurring through (1) national biennial measurement of state PHLs' abilities to meet the Core Functions and Capabilities of State PHLs, (2) the new Laboratory System Improvement Program (L-SIP) for the SPH Laboratory System, and (3) sharing ideas to integrate and improve the SPH Laboratory System (e.g., using the L-SIP Online Resource Center). Public health emergencies, such as the recent H1N1 epidemic, illustrate and reinforce the need for a strong NLS within which federal, public health, and clinical (i.e., hospital and private reference) laboratories function in close collaboration.

A veterinary perspective on methicillin-resistant staphylococci

OBJECTIVE

To familiarize the reader with the epidemiology, diagnosis, and infectious and zoonotic potential of methicillin-resistant staphylococci.

DATA SOURCES

Original research publications, scientific reviews and abstracts, case reports, and conference proceedings.

HUMAN DATA SYNTHESIS

Staphylococcus aureus is a common human commensal organism; acquisition of genes encoding an altered penicillin-binding protein confers resistance to beta-lactam antimicrobial drugs. Methicillin-resistant S. aureus (MRSA) are often resistant to non-beta-lactam antimicrobial drugs as well. Originally described as an important cause of nosocomial infection, MRSA colonization and infection are now often identified in humans outside healthcare settings. Like other S. aureus, MRSA may be present without clinical illness. However, when they do cause infection the consequences can be extremely serious.

VETERINARY DATA SYNTHESIS

The major domestic animal species, including pets and livestock, may become contaminated, colonized, or infected with methicillin-resistant staphylococci, including MRSA. Dogs and cats are more likely to be colonized/infected with Staphylococcus pseudintermedius than S. aureus, but this pathogen can acquire genes encoding methicillin resistance (ie, MRSP). Diagnosis of MRSA or MRSP has implications not only for treatment of infected animals, but for potential zoonotic transmission.

CONCLUSIONS

MRSA infection is an important cause of morbidity and mortality in humans. Animals may be contaminated, colonized, or infected with MRSA, with implications for the animal's health and as a potential reservoir for human infection. Staphylococci other than S. aureus may also acquire genes for methicillin resistance, and these species can also result in animal and occasionally human morbidity or mortality.

Systematic review of antibiograms: A National Laboratory System approach for improving antimicrobial susceptibility testing practices in Michigan

OBJECTIVES

Public health surveillance is often dependent on sentinel testing performed in clinical microbiology laboratories, and recognition of emerging/ unusual antimicrobial resistance is especially challenging. We obtained cumulative antibiograms from hospitals to determine whether clinical laboratories recognized unusual resistance or reported antimicrobials inappropriate for various bacterial species, as measured before and after public health laboratory (PHL) educational and technical-support interventions.

METHODS

We compared cumulative antibiogram data from 81 clinical laboratories servicing 86 hospitals in Michigan from 2000 through 2005 with a standardized checklist derived from Clinical and Laboratory Standards Institute (CLSI) antimicrobial susceptibility testing (AST) documents. We considered the reporting of unlikely percent-susceptible results and/or inappropriate antimicrobials serious errors, and we calculated error rates for each data year. We used CLSI-recommendation compliance as a measure to determine whether laboratories were implementing changes.

RESULTS

Ninety-five of 239 (28%) cumulative antibiograms examined had one or more serious errors. The annual number of cumulative antibiograms with serious errors did not change radically (range: 10-13); however, when expressed as a percentage of cumulative antibiograms received, the occurrence of these errors declined from 59% in 2000 to 19% in 2005. The reporting of misleading or dangerous antimicrobial-organism combinations occurred less frequently than the reporting of unlikely percent-susceptible results. Compliance with new CLSI recommendations did not improve significantly.

CONCLUSIONS

AST is complex and nuanced. PHL programs can provide resources, guidance, and technical support to help clinical microbiologists differentiate questionable AST results from true emerging antimicrobial resistance.