Disc Test for Detecting Staphylococcus aureus Strains Producing Type A and Type C ß-Lactamases.

Staphylococcus aureus can produce ß-lactamases capable of hydrolyzing penicillins and first-generation cephalosporins. The propensity of type A and type C ß-lactamase-producing S. aureus (TAPSA and TCPSA) to hydrolyze cefazolin at a high inoculum is termed the cefazolin inoculum effect (CIE). Strains with a CIE have a theoretical risk of causing treatment failure and are unable to be detected routinely by most laboratories. We developed a high-performing yet straightforward ß-lactamase disc test that identifies and differentiates both TAPSA and TCPSA and is suitable for routine diagnostic laboratory workflows. Clinical isolates of S. aureus resistant to penicillin were identified, and their blaZ genes were sequenced. MICs were determined at low and high inocula (5 × 105 CFU/mL and 5 × 107 CFU/mL), and isolates demonstrating a CIE were characterized. A semimechanistic model was established to describe differential hydrolysis patterns, and candidate models were iteratively assessed using area-under-the-curve analysis from competitor receiver operating characteristic (ROC) curves. Biomarker thresholds were derived from Youdon index-derived optimal cutoff values. Genetic analysis of 99 isolates identified 26 TAPSA isolates and 45 TCPSA isolates. The model best differentiating TAPSA from non-TAPSA utilized cefazolin-to-cephalothin ratio analysis (sensitivity, 96.2%; specificity, 98.6%). The model best differentiating TCPSA from non-TCPSA incorporated cefazolin, cephalothin, and oxacillin (sensitivity, 88.6%; specificity, 96.6%). TAPSA and TCPSA can be differentiated using three antibiotic discs on a single agar plate. The test has potential value in typing the ß-lactamase type from isolates from patients that are candidates for or have failed cefazolin therapy. IMPORTANCE The key significance of this article is that it details a straightforward method of performing a disc test that can differentiate Staphylococcus aureus isolates that are likely to be associated with a cefazolin inoculum effect and theoretical risk of cefazolin treatment failure from isolates that are less likely to be associated with a cefazolin inoculum effect.

Phage Therapy of Mycobacterium Infections: Compassionate Use of Phages in 20 Patients With Drug-Resistant Mycobacterial Disease.

BACKGROUND: Nontuberculous Mycobacterium infections, particularly Mycobacterium abscessus, are increasingly common among patients with cystic fibrosis and chronic bronchiectatic lung diseases. Treatment is challenging due to intrinsic antibiotic resistance. Bacteriophage therapy represents a potentially novel approach. Relatively few active lytic phages are available and there is great variation in phage susceptibilities among M. abscessus isolates, requiring personalized phage identification. METHODS: Mycobacterium isolates from 200 culture-positive patients with symptomatic disease were screened for phage susceptibilities. One or more lytic phages were identified for 55 isolates. Phages were administered intravenously, by aerosolization, or both to 20 patients on a compassionate use basis and patients were monitored for adverse reactions, clinical and microbiologic responses, the emergence of phage resistance, and phage neutralization in serum, sputum, or bronchoalveolar lavage fluid. RESULTS: No adverse reactions attributed to therapy were seen in any patient regardless of the pathogen, phages administered, or the route of delivery. Favorable clinical or microbiological responses were observed in 11 patients. Neutralizing antibodies were identified in serum after initiation of phage delivery intravenously in 8 patients, potentially contributing to lack of treatment response in 4 cases, but were not consistently associated with unfavorable responses in others. Eleven patients were treated with only a single phage, and no phage resistance was observed in any of these. CONCLUSIONS: Phage treatment of Mycobacterium infections is challenging due to the limited repertoire of therapeutically useful phages, but favorable clinical outcomes in patients lacking any other treatment options support continued development of adjunctive phage therapy for some mycobacterial infections.

Gauge against the machine: revisiting quality for multi-targeted serology platforms.

Diagnosis of infections of public health significance, such as leptospirosis, often present challenges for laboratories. To counter common challenges and ensure quality driven health responses, rigorous validation and verification processes are required. Despite such rigor, however, can one be certain laboratory reports are truly reflective of infection, given the risk of rare, but potentially very significant quality oversights? Here we present a real-world scenario where diagnosis of leptospirosis cases was compromised over a 6-year period despite quality measures suggesting a well performing serological assay. A subsequent investigation revealed this was attributed to the programming of an automated microtitration plate analyser, evading detection by both quality control and external quality assurance processes. The quality oversight provides insight into potential limitations in quality processes in multi-targeted serological platforms.

Predisposing factors, microbiological features and outcomes of patients with clinical presumed concomitant microbial and herpes simplex keratitis.

BACKGROUND/OBJECTIVES: To describe the predisposing factors, pathogens and outcomes in patients with clinical presumed concomitant microbial and herpes simplex keratitis (HSK) at Sydney Eye Hospital, Australia over a 5-year period. SUBJECTS/METHODS: A retrospective case review was conducted. Patients with clinical presumed concomitant microbial and HSK from 2012 to 2016 were identified from pathology and hospital coding databases. Data were extracted from the medical records. VA was converted to the logarithm of the minimum angle of resolution (logMAR). 'Poor' outcome was defined as final VA worse than 6/60, or decrease in VA during treatment, or presence of complication, or needed surgical intervention. RESULTS: 126 episodes in 121 patients were included; median age 70 years (range 18-96); 56% male. Predisposing factors included blepharitis 20/126 (16%) cases, and corneal transplantation 19 (15%). Forty-six (37%) cases had prior HSK. Coagulase-negative staphylococci 51/116 (44%), Staphylococcus aureus 11 (9%), and Pseudomonas aeruginosa 11 (9%) were the most common isolates. The median VA at initial visit was 1.7 logMAR (range 0.04-2.7) and at final visit, 0.98 logMAR (range 0-2.7) (P < 0.05). Complications occurred in 70 episodes: persistent epithelial defect in 38 (30%); intraocular pressure elevation in 15 (12%), and corneal perforation in 12 (10%). 'Poor' outcome was recorded in 46/75 (61%) episodes. CONCLUSIONS: Patients with clinical presumed concomitant microbial and HSK face significant ocular morbidity and poor visual outcome. In our setting, previous HSK, corneal and ocular surface disease, were common predisposing factors and Gram-positive bacteria were the most commonly associated organisms.

Australian Meningococcal Surveillance Programme Annual Report, 2020.

ABSTRACT: Invasive meningococcal disease (IMD) is a notifiable disease in Australia, and both probable and laboratory-confirmed cases of IMD are reported to the National Notifiable Diseases Surveillance System (NNDSS). In 2020, there were 90 notifications of IMD, the lowest number documented since records began in the NNDSS in 1991. Of these, 97% (87/90) were laboratory-confirmed cases, with 70% (61/87) confirmed by bacterial culture and 30% (26/87) by nucleic acid amplification testing. The serogroup was determined for 85/87 laboratory-confirmed cases of IMD: serogroup B (MenB) accounted for 64% of infections (54/85); MenW for 19% (16/85); MenY for 16% (14/85); and MenC 1.2% (1/85). Fine typing was available on 60/85 (71%) of cases with serogroup determined; of the typed MenW, all were PorA antigen type P1.5,2 and sequence type 11, the hypervirulent strain reported in recent outbreaks in Australia and overseas. The primary peaks of IMD notifications in Australia in 2020 were observed in infants less than 1 year (16/87, 18%) and in adults aged 45-64 years (14/87, 16%). MenB infections predominated in those aged less than 5 years and 15-19 years; MenW and MenY infections predominated in those aged 45 years or more. All 61 IMD isolates were tested for antimicrobial susceptibility: none were penicillin resistant; however, 56/61 (92%) had decreased susceptibility to penicillin. All isolates were susceptible to ceftriaxone, ciprofloxacin and rifampicin.

Australian Gonococcal Surveillance Programme Annual Report, 2019.

The Australian Gonococcal Surveillance Programme (AGSP) has continuously monitored antimicrobial resistance in clinical isolates of Neisseria gonorrhoeae since 1981. In 2019, a total of 9,668 clinical isolates of gonococci from the public and private sector in all jurisdictions were tested for in vitro antimicrobial susceptibility by standardised methods. The current treatment recommendation for gonorrhoea, for the majority of Australia, continues to be dual therapy with ceftriaxone and azithromycin. Decreased susceptibility (DS) to ceftriaxone (minimum inhibitory concentration [MIC] value ≥ 0.06 mg/L) was found nationally in 1.3% of isolates. Five N. gonorrhoeae clinical isolates were ceftriaxone-resistant (MIC value ≥ 0.25 mg/L), and therefore also resistant to penicillin; all were resistant to ciprofloxacin but susceptible to azithromycin. These isolates were reported from Victoria (3), non-remote Western Australia (1) and New South Wales (1). Resistance to azithromycin (MIC value ≥ 1.0 mg/L) was found nationally in 4.6% of N. gonorrhoeae isolates, continuing a downward trend observed and reported since 2017. Isolates with high-level resistance to azithromycin (MIC value ≥ 256 mg/L) continue to be reported sporadically in Australia, with eight detected in 2019: two each from New South Wales, Queensland, and Victoria, and one each from Tasmania and non-remote Western Australia. In 2019, in Australia, 2,136 gonococcal isolates (22.1%) were penicillin resistant; however, there remains considerable variation by jurisdiction, and in some remote settings there is little resistance and this drug is recommended empiric therapy. In 2019, in the remote Northern Territory, no penicillin resistance was reported, however in remote Western Australia six out of 85 isolates (7.1%) were penicillin resistant. There was no ciprofloxacin resistance reported from isolates tested from remote regions of the Northern Territory, and ciprofloxacin resistance rates remain comparatively low (7/85; 8.2%) in remote Western Australia.

Australian Gonococcal Surveillance Programme Annual Report, 2018.

The Australian Gonococcal Surveillance Programme (AGSP) has continuously monitored antimicrobial resistance in clinical isolates of Neisseria gonorrhoeae from all states and territories since 1981. In 2018, there were 9,006 clinical isolates of gonococci from public and private sector sources tested for in vitro antimicrobial susceptibility by standardised methods. This was the highest annual total of isolates tested since the inception of the AGSP. The current treatment recommendation for gonorrhoea, for the majority of Australia, remains dual therapy with ceftriaxone and azithromycin. Decreased susceptibility to ceftriaxone (minimum inhibitory concentration (MIC) value ≥0.06 mg/L) was found nationally in 1.73% of isolates. The highest proportions were reported from Tasmania and non-remote Western Australia (7.3% and 2.1% respectively). In 2018 two extensively drug-resistant isolates were reported from Queensland patients. These two isolates, with ceftriaxone MIC values of 0.50 mg/L, high-level resistance to azithromycin (MIC ≥ 256 mg/L), and resistance to penicillin and ciprofloxacin were identified and reported to the World Health Organization as isolates of international significance. Resistance to azithromycin (MIC value ≥1.0 mg/L) was found nationally in 6.2% of isolates, lower than the 9.3% reported in 2017, but more than double the proportion reported in 2015 (2.6%). The highest proportions were reported from the Australian Capital Territory (8.7%), Victoria (8.3%), and New South Wales (6.5%). High-level resistance to azithromycin (MIC value ≥256 mg/L) was reported in nine isolates nationally in 2018: four from New South Wales, three from Victoria, and two from Queensland. The proportion of isolates resistant to penicillin in non-remote Australia ranged from 8.8% in non-remote Northern Territory to 44.1% in South Australia. In remote Northern Territory penicillin resistance rates remain low (1.9%), and higher in remote Western Australia (6.5%). The proportion of isolates resistant to ciprofloxacin in non-remote Australia ranged from 10.3% in non-remote Northern Territory to 48.3% in South Australia. Ciprofloxacin resistance rates remain comparatively low in remote Northern Territory (1.9%) and remote Western Australia (4.6%).

Antimicrobial resistance trends in bacterial keratitis over 5 years in Sydney, Australia.

IMPORTANCE: Antimicrobial resistance (AMR) patterns in bacterial keratitis may fluctuate in a geographic location over time. BACKGROUND: To investigate any change in AMR patterns in Sydney, Australia. DESIGN: Retrospective case series. PARTICIPANTS: All patients with microbial keratitis who underwent a corneal scrape and culture from 2012 to 2016 at the Sydney Eye Hospital. METHODS: Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry identified organisms. The Calibrated Dichotomous Susceptibility method determined antibiotic susceptibilities. MAIN OUTCOME MEASURES: Isolated organisms and antibiotic susceptibilities. RESULTS: There were 1084 corneal scrapes from 957 patients. The mean age was 54 years (range 18-100) and 52% were male. Cultures were positive in 711 of 1084 scrapes (66%), with 884 organisms identified. Of the bacteria isolated, 685 of 884 (78%) were Gram-positive and 199 of 884 (22%) were Gram-negative. Overall, the most common bacteria were coagulase-negative Staphylococci (CoNS) (405/884, 46%). Methicillin-resistance was detected in 7% of Staphylococcus aureus isolates (7/103). Methicillin-resistance in CoNS (ie, also cefalotin resistance) was reported in 19% of isolates and ciprofloxacin 8%. For methicillin-sensitive S aureus (MSSA), 5% of isolates were resistant to ciprofloxacin. For Corynebacterium spp., 34% of isolates were resistant to chloramphenicol and 9% to ciprofloxacin. The most common Gram-negative bacteria was Pseudomonas aeruginosa (109/199, 55%). One case was resistant to ciprofloxacin. CONCLUSIONS AND RELEVANCE: Coagulase-negative staphylococcal species were the most frequently suspected of causing bacterial keratitis. Increased resistance to cefalotin was identified for CoNS and to ciprofloxacin for Corynebacterium spp., MSSA and P aeruginosa compared to a previous study in Sydney in 2002 to 2003.

Australian Meningococcal Surveillance Programme annual report, 2017.

In 2017, there were 374 laboratory-confirmed cases of invasive meningococcal disease (IMD) analysed by the Australian National Neisseria Network. This was the highest number of laboratory-confirmed cases since 2003. Probable and confirmed cases of IMD are notifiable in Australia; there were 379 IMD cases notified to the National Notifiable Diseases Surveillance System in 2017, the highest number reported since 2005. Meningococcal sero-grouping was determined for 98% (367/374) of laboratory-confirmed IMD cases. Serogroup B infections accounted for 137 cases (37%). The number of serogroup W infections (141 cases, 38%) in 2017 was the highest since the Australian Meningococcal Surveillance Programme (AMSP) began. In addition, the number and proportion of serogroup Y infections (75 cases, 20%) was also the highest recorded by the AMSP. Molecular typing results were available for 315 of the 374 IMD cases (83%). Of the serogroup W IMD strains that were able to be genotyped, 97% (125/129) had the PorA antigen encoding gene type P1.5,2 and of these, 59% (74/125) were sequence type 11, the same type as the hypervirulent serogroup W strain that has been circulating in the UK and South America since 2009. The primary IMD age peak was observed in adults aged 45 years or more, whilst secondary disease peaks were observed in those aged less than 5 years. Serogroup B infections predominated in the age group 15-19 years. Serogroup W infections predominated in those aged 65 years or more. Serogroup Y infections were predominately seen in adults aged 45 years or more. Of the IMD isolates tested for antimicrobial susceptibility, 5.1% (14/276) were resistant to penicillin; decreased susceptibility to penicillin was observed in a further 89% (247/276) of isolates. All isolates tested were susceptible to ceftriaxone; two isolates were less susceptible to ciprofloxacin; and one isolate was resistant to rifampicin.

Systematic review and survey of Neisseria gonorrhoeae ceftriaxone and azithromycin susceptibility data in the Asia Pacific, 2011 to 2016.

BACKGROUND: Antimicrobial resistance in Neisseria gonorrhoeae is a global concern, with the ongoing emergence of ceftriaxone and azithromycin resistance threatening current treatment paradigms. To monitor the emergence of antimicrobial resistance in N. gonorrhoeae, the World Health Organization (WHO) Gonococcal Antimicrobial Surveillance Programme (GASP) has operated in the Western Pacific and South East Asian regions since 1992. The true burden of antimicrobial resistance remains unknown. In response, the objective of this study was to survey ceftriaxone and azithromycin susceptibility in N. gonorrhoeae across the western Pacific and south-east Asia, and interlink this data with systematically reviewed reports of ceftriaxone and azithromycin resistance. METHODS AND FINDINGS: The WHO Collaborating Centre for Sexually Transmitted Infections and Antimicrobial Resistance, Sydney, coordinated annual surveys of gonococcal susceptibilities with participating laboratories, and additionally undertook a systematic review of reports detailing gonococcal ceftriaxone and azithromycin susceptibility data for locations geographically in the Asia Pacific from 2011 to 2016. It was found that surveillance of gonococcal antimicrobial resistance remains limited in the Asia Pacific, with weaker surveillance of azithromycin versus ceftriaxone. Ninety-three published reports were identified (including national reports) which documented susceptibility data for ceftriaxone and azithromycin. GASP survey data was available for 21 countries, territories or areas, and suggested MICs are increasing for ceftriaxone and azithromycin. Between 2011 and 2016, the percentage of locations reporting >5% of gonococcal isolates with MICs to ceftriaxone meeting WHO's definition of decreased susceptibility (MIC ≥ 0.125 mg/L) increased from 14.3% to 35.3% and the percentage of locations reporting >5% of gonococcal isolates with azithromycin resistance (MIC ≥ 1 mg/L) increased from 14.3% to 38.9%. Published reports were available for several countries that did not provide GASP surveillance responses for ceftriaxone (n = 5) and azithromycin (n = 3) respectively. Over the study period, there was a 183% increase in the number of countries providing surveillance data for GASP for both ceftriaxone and azithromycin, and a 30.6% increase in ceftriaxone MIC testing across the Asia Pacific facilitated by this project. CONCLUSION: This study provides the first comprehensive illustration of increasing MICs to ceftriaxone in the Asia Pacific. The survey and literature review additionally detail increasing resistance to azithromycin. Further surveillance system strengthening is required to monitor these trends in order to address and curb gonococcal AMR in the region.

Australian Gonococcal Surveillance Programme Annual Report, 2017

The Australian Gonococcal Surveillance Programme (AGSP) has continuously monitored antimicrobial resistance in clinical isolates of Neisseria gonorrhoeae from all states and territories since 1981. In 2017, there were 7,835 clinical isolates of gonococci from public and private sector sources tested for in vitro antimicrobial susceptibility by standardised methods. Current treatment recommendations for gonorrhoea for the majority of Australia, is a dual therapeutic strategy of ceftriaxone and azithromycin. Decreased susceptibility to ceftriaxone (Minimum Inhibitory Concentration or MIC value 0.06-0.125 mg/L) was found nationally in 1.06% of isolates, which is lower than that reported in the AGSP Annual Report 2016 (1.7%). The highest proportions were reported from Victoria and Western Australia (urban and rural) (2.1% and 1.4% respectively). Resistance to azithromycin (MIC value ≥1.0 mg/L) was found nationally in 9.3% of isolates, which is approximately double the proportion reported in 2016 (5.0%) and more than three times the proportion reported in 2015 (2.6%). The highest proportions were reported from Victoria (13.5%), South Australia (12.8%) and New South Wales (9.3%). High level resistance to azithromycin (MIC value ≥256 mg/L) was reported in 4 strains nationally in 2017, 2 from Victoria, one from New South Wales, and one from Queensland. The proportion of strains resistant to penicillin in non-remote Australia ranged from 10.3% in non-remote Northern Territory to 44.1% in Tasmania. In remote Northern Territory, penicillin resistance rates remain low (2.5%). In remote Western Australia, penicillin resistance rates continue to increase (6.7%) compared to the previous years, however, there were relatively low numbers of strains available for isolate based testing (n=12). To address this and to monitor resistance and inform treatment guidelines, widespread molecular testing for penicillin resistance in Western Australia is in place, and these data are included in the AGSP. The proportion of strains resistant to ciprofloxacin in non-remote Australia ranged from 17.2% in non-remote Northern Territory to 61% in Tasmania. Ciprofloxacin resistance rates remain comparatively low in remote Northern Territory (1.3%) and remote Western Australia (5.0%).

Epidemiology of Late and Very Late Onset Group B Streptococcal Disease: Fifteen-Year Experience From Two Australian Tertiary Pediatric Facilities.

BACKGROUND: Group B Streptococcus (GBS) is a recognized cause of sepsis and meningitis, particularly in infants. Early onset (<7 days) GBS disease has been well characterized, whereas the epidemiology of late onset disease (LOD, 7-89 days) and very late onset disease (VLOD, ≥90 days) is less well understood. The aims of this study were to assess risk factors, presentation, management and outcome for GBS LOD and VLOD. METHODS: Microbiology laboratory databases and hospital diagnostic coding for Sydney Children's Hospital and the Children's Hospital at Westmead were investigated for patients ≥7 days of age diagnosed with GBS bloodstream infection or meningitis from January 1, 2000 to December 31, 2014 (15 years). Subjects' medical records were reviewed to confirm diagnosis and analyze risk factors, presentation, management and outcome. RESULTS: Eighty-seven cases of LOD and 28 cases of VLOD were identified, including 49 cases of bloodstream infection and 66 cases of meningitis. No significant differences in risk factors or presentation were identified between LOD and VLOD. Patients with LOD were more likely to develop sequelae compared with VLOD [odds ratio (OR): 3, 95% confidence interval (CI): 1.03-8.77]. Female sex was the only significant risk factor identified for GBS meningitis (OR: 3.5, 95% CI: 1.5-8.1). GBS meningitis was significantly associated with neurodevelopmental impairment or death compared with bloodstream infection (OR: 30, 95% CI: 6.4-140.6). CONCLUSIONS: GBS LOD and VLOD are encountered in similar at-risk populations, with LOD associated with higher morbidity. Infants presenting with meningitis are at significantly higher risk of sequelae compared with bloodstream infection.

Prolonged second diagnostic window for human immunodeficiency virus type 1 in a fourth-generation immunoassay: are alternative testing strategies required?

Diagnosis of acute HIV is done by patient history and examination and testing of RNA, proviral DNA, and serology using fourth-generation antigen/antibody detection assays. We describe an HIV-1 primary infection with a second diagnostic window of 18 to 34 days on a fourth-generation immunoassay, which would have been missed using some current algorithms. Caution must be exercised when fourth-generation HIV-1 immunoassays are interpreted in isolation, and additional testing should be considered depending on patient risk assessment.

Development of the idea of chronic renal failure.

Ancient literature contained suggestions of references to people whom we might now speculate suffered from chronic renal failure; however, the first glimmerings of an understanding of the subject arose out of the clinico-pathological correlations that a number of 18th and 19th century observers drew. The concurrent studies by chemists of circulating and urinary levels of urea, creatinine, urate, phosphate, potassium, sodium and hydrogen ions expanded those correlations to a pathophysiological domain, especially in the late 19th and early 20th centuries. With the subsequent development of ideas about circulating hormones and the development of techniques for their measurement during the 20th century, the contemporary idea of chronic renal failure developed. The development of methods for quantifying tests of renal function enhanced that undertaking. Then, in the latter half of the 20th century, the development of effective dialytic techniques for the treatment of patients who suffer from chronic renal failure brought a renewed focus upon the mechanisms involved and problems posed by existing ideas. Nevertheless, the continuing high morbidity and mortality of patients who require such treatment suggest that existing ideas remain quite imperfect.

The contribution of nephrology to the development of current concepts of disease.

Historians and philosophers of science rarely comment upon nephrological contributions to the development of general concepts of disease. In the present study, I examine this topic by starting from the premises that an idea of disease pervades most human societies, that received explanations of disease vary between people, societies and eras, and that an understanding of renal disease has often reflected general explanatory trends. Traditionally, most students of disease have belonged to one of four schools: descriptive, causal, mechanistic, or statistical. Descriptivists have tended to focus on manifestations, be these of a symptomatic, a structural, or a functional type. Causationists have focussed upon identification of the origins of diseases. Mechanists have emphasised pathogenetic processes. Statisticians have calculated mathematical differences of parameters from the mean ('the normal'), without explaining the reasons for these. Mechanists currently appear to hold the ascendancy in nephrology through their focus upon the links that connect causes with manifestations. As, however, all schools of thought have historically waxed and waned, I question the wisdom of granting any of them hegemony. Rather, I promote an event idea of disease that encompasses the causal, mechanistic and descriptive schools. Such considerations should assist nephrologists both to treat disease and to identify those of their predecessors who most advanced knowledge.