Clostridium difficile as a cause of healthcare-associated diarrhoea among children in Auckland, New Zealand: clinical and molecular epidemiology.

We aimed to determine the incidence of Clostridium difficile infection (CDI), the molecular epidemiology of circulating C. difficile strains and risk factors for CDI among hospitalised children in the Auckland region. A cross-sectional study was undertaken of hospitalised children <15 years of age in two hospitals investigated for healthcare-associated diarrhoea between November 2011 and June 2012. Stool specimens were analysed for the presence of C. difficile using a two-step testing algorithm including polymerase chain reaction (PCR). C. difficile was cultured and PCR ribotyping performed. Demographic data, illness characteristics and risk factors were compared between children with and without CDI. Non-duplicate stool specimens were collected from 320 children with a median age of 1.2 years (range 3 days to 15 years). Forty-six patients (14 %) tested met the definition for CDI. The overall incidence of CDI was 2.0 per 10,000 bed days. The percentage of positive tests among neonates was only 2.6 %. PCR ribotyping showed a range of strains, with ribotype 014 being the most common. Significant risk factors for CDI were treatment with proton pump inhibitors [risk ratio (RR) 1.74, 95 % confidence interval (CI) 1.09-5.59; p = 0.002], presence of underlying malignancy (RR 2.71, 95 % CI 1.65-4.62; p = 0.001), receiving chemotherapy (RR 2.70, 95 % CI 1.41-4.83; p = 0.003) and exposure to antibiotics (RR 1.17, 95 % CI 0.99-1.17; p = 0.03). C. difficile is an important cause of healthcare-associated diarrhoea in this paediatric population. The notion that neonatal populations will always have high rates of colonisation with C. difficile may not be correct. Several risk factors associated with CDI among adults were also found to be significant.

Phylogenetic lineages of tuberculosis isolates in New Zealand and their association with patient demographics.

SETTING: In New Zealand, the lineage genotypes of Mycobacterium tuberculosis clinical isolates and their role in the epidemiology of tuberculosis (TB) are currently unknown. OBJECTIVE: 1) To measure the relative frequency of each phylogenetic lineage of the M. tuberculosis complex in New Zealand, and 2) to examine its relationship with patient demographics and multidrug-resistant TB (MDR-TB). METHODS: All non-duplicate M. tuberculosis complex isolates recovered in 2010 and 2011 underwent large sequence polymorphism and/or single nucleotide polymorphism analyses. Mycobacterial interspersed repetitive units (MIRU) profiling was also performed for cluster identification. RESULTS: New Zealand isolates were dominated by lineage 4 (Euro-American: 37.8%, 95%CI 33.6-42.2), followed by lineage 1 (Indo-Oceanic: 22.6%, 95%CI 19.1-26.5), lineage 2 (East Asian: 19.5%, 95%CI 16.2-23.3) and lineage 3 (East-African Indian, which included Central Asian: 17.7%, 95%CI 14.5-21.3). Lineage 2 accounted for 58.1% of MDR-TB cases from 2002 to 2011. Among immigrants, the predominant lineages corresponded to high prevalence lineages in the country of origin. In New Zealand-born individuals, Maori and NZ Europeans share the same predominant lineage, lineage 4, with a higher proportion of non-unique MIRU types observed in Maori cases. Lineage 3 was more prevalent in Maori than in NZ Europeans. CONCLUSION: In New Zealand, M. tuberculosis complex phylogenetic lineage is associated with TB epidemiology in terms of ethnicity, country of origin and MDR-TB.

Comparative epidemiology of CTX-M-14 and CTX-M-15 producing Escherichia coli: association with distinct demographic groups in the community in New Zealand.

Extended spectrum beta-lactamase producing E. coli (ESBL-EC) are an emerging public health issue. In New Zealand (NZ), bla (CTX-M-14) and bla (CTX-M-15) are the most common ESBL genes. Although many studies describe risk factors for ESBL-EC, few describe risk factors for specific ESBL genes. Between January 2006 and December 2007, we characterized 108 consecutive, non-duplicate isolates of ESBL-EC at the Auckland Hospital laboratory. Demographic and clinical data were recorded. Of the 108, 54.6% (59) were CTX-M-15-EC, 26.9% (29) were CTX-M-14-EC and 12.09% were CTX-M-9 (13). The remaining seven isolates carried CTX-M-3 (3; 2.7%), CTX-M-65 (2; 1.8%), CTX-M-27 (1; 0.9%) and CTX-M-57 (1; 0.9%). CTX-M-15-EC were more likely than CTX-M-14-EC to be fluoroquinolone-resistant (86.4% versus 32.4%; p=0.006) and to be non-susceptible to amoxicillin-clavulanate (84.7% versus 41.4%; p=0.0001). Patients with CTX-M-15-EC were more likely to be of Indian ethnicity (34.5% versus 0%; p=0.0012) and to have travelled recently (31.6% versus 4%; p=0.0088). Patients with CTX-M-14-EC were more likely to have Chinese or South-East Asian ethnicity (48.1% versus 5.2%; p<0.0001) and to have no history of either travel or prior hospital admission (44% versus 8.9%; p=0.0006). These data imply that CTX-M-15 and CTX-M-14 producing E. coli are associated with distinct demographic subgroups in NZ.

High rates of susceptibility to ceftazidime among globally prevalent CTX-M-producing Escherichia coli: potential clinical implications of the revised CLSI interpretive criteria.

The CTX-M family of extended-spectrum ß-lactamases (ESBLs) is a significant global public health threat. The prevalence of specific bla (CTX-M) genes varies geographically, but bla (CTX-M-15) and bla (CTX-M-14) dominate in most countries. We applied the latest Clinical Laboratory Standards Institute (CLSI) interpretive criteria (M100-S20) to a diverse collection of ESBL-producing Escherichia coli strains obtained from clinical specimens in our laboratory. Whereas under previous CLSI recommendations all isolates in this strain collection would have been reported as ceftazidime-resistant, under the new recommendations, approximately 11% of CTX-M-15-producing E. coli and 93% of CTX-M-14-producing E. coli respectively tested as ceftazidime-susceptible. We also found that, whilst many CTX-M-14-producers had minimum inhibitory concentrations (MICs) less than the breakpoint of 4 mg/L, the MIC distribution for these strains was higher than that of wild-type E. coli, with one CTX-M-14-producing isolate having an MIC of >64 mg/L. Although the new CLSI recommendations imply that ceftazidime can be safely used to treat serious infections due to CTX-M-producing E. coli, clinical outcome data are lacking. Consequently, the widespread use of ceftazidime in this setting could have profound clinical implications.

Clinical failures associated with rpoB mutations in phenotypically occult multidrug-resistant Mycobacterium tuberculosis.

SETTING: Recently, Mycobacterium tuberculosis isolates have been described that test phenotypically susceptible to rifampicin (RMP) yet harbour genotypic rpoB mutations. OBJECTIVE: 1) To investigate the impact of such mutations on clinical outcomes among RMP-susceptible isolates, and 2) to determine the prevalence of rpoB mutations among isoniazid (INH) monoresistant isolates at our laboratory and to describe the association between the presence of these mutations and clinical outcomes. METHODS: M. tuberculosis isolates were screened for mutations in the rpoB gene using the Cepheid Gene-Xpert® MTB/RIF assay. Clinical correlation was made by reviewing patient case notes. RESULTS: Isolates from 94 patients were found to have INH-resistant, RMP-susceptible profiles. Clinical information was available for 52 patients, including three whose isolates had rpoB mutations. All three of these patients had treatment failures, compared to two of 49 patients whose isolates did not have rpoB mutations (P = 0.0005). DISCUSSION: We demonstrate a significant association between the presence of rpoB gene mutations that are not detected at the current RMP critical concentration and treatment failure. We suggest that a review of the current RMP critical concentration is warranted to ensure that RMP is not used inappropriately for the treatment of phenotypically occult multidrug-resistant tuberculosis.

Corynebacterium diphtheriae endocarditis: a case series and review of the treatment approach.

OBJECTIVES: Infective endocarditis due to non-toxigenic Corynebacterium diphtheriae is uncommon; we report 10 cases occurring over a 14-year period in Auckland, New Zealand and review the approach for treatment. CASE SERIES: Eight of the 10 patients had known prosthetic valves or homografts in situ. Three patients required surgical intervention for infective endocarditis. Seven patients were treated with a combination of ß-lactam and aminoglycoside, and one each was treated with a combination of vancomycin and an aminoglycoside, a ß-lactam alone, and vancomycin alone. All patients survived and none relapsed. REVIEW OF LITERATURE: The antibiotic treatment of 46 previously reported cases was reviewed; patients treated with a ß-lactam and aminoglycoside (n=25), and without the addition of an aminoglycoside (n=11) were compared. The differences in length of treatment within each group make the comparison of outcome (mortality, need for surgical intervention, disease and treatment complications) difficult. However, regardless of the length of treatment, there was no difference in mortality or need for surgical intervention between the two groups in the currently published cases. CONCLUSIONS: Current evidence suggests that endocarditis of either native or prosthetic valves, caused by penicillin-susceptible C. diphtheriae, demonstrates a favorable outcome when treated with either a ß-lactam alone or in combination with an aminoglycoside. Patient-specific factors will determine which approach is more appropriate for each individual patient.

Seasonal peaks in Escherichia coli infections: possible explanations and implications.

Escherichia coli is a common cause of infections in all populations and countries of the world, causing an enormous burden of disease. In this issue of Clinical Microbiology and Infection, Al-Hasan et al. describe seasonal peaks in the incidence of E. coli bloodstream infection (BSI) during the summer for a population of 125 000 in Minnesota, USA. We discuss the probability that similar seasonal peaks in the incidence of E. coli BSI occur in other populations and geographical regions. Second, we discuss possible underlying explanations for these findings in terms of seasonal changes in human behaviour and the effect of temperature on the ability of E. coli to survive in the environment. Finally, we discuss some of the possible implications of E. coli BSI being a seasonal illness. More specifically, we discuss how better understanding the reasons for seasonality may potentially help us to better understand the dominant routes by which human populations are exposed to clonal groups of E. coli associated with urinary tract infection.

Ivan Basilevich: a gerontologist in transit.

Chance often determines the names that are recorded in history. Among an earlier generation's gerontologists, Ivan Basilevich was distinguished by the promise of his career and recognition in the USSR by his peers. The military invasion of his nation changed the pattern of his life. From a professional level in his native land, at the age of 50, he became a resident in psychiatry in Rhode Island where he continued his work on aging. He became a citizen in 1954 and by 1962 was the senior psychiatrist of his hospital's staff. His contributions to gerontology included his participation in the Kiev Congress of Aging in 1938 and a monograph in English (unpublished) on the medical aspects of natural old age. He wrote some 70 articles. In his papers on the subject of aging he heralded the transition of gerontology to its modern stage.

Albert Mueller-Deham: distinguished geriatric clinician.

Modern geriatrics is the product of notable clinicians, past and present. However, recognition has been unequal. Pioneers whose publications were pre-eminent in their time have not received adequate identification. In consequence, the field is poorer for such neglect. Albert Mueller-Deham (1881-1971) of Vienna did excellent work in geriatrics. His clinical abilities were based on long staff attendance at a major hospital and by his insistence on attendance, with his staff, at autopsies. His key textbook was published in 1937 in German. His career in Austria was disrupted by political forces but, with energy and ability, he continued it with distinction in the United States. After retirement at age 70, he turned to social writings. A bio-bibliography of this noteworthy man is based on several letters, a personal narrative that he wrote in response to questions about his years in geriatrics, notes from one of his staff, and recollections by his co-author in 1942 of the revised American edition of the book. Students of aging can benefit by recourse to his classical text with its group of clinical principles.