Incidence and molecular characterization of extended-spectrum beta-lactamase (ESBL)-producing Salmonella enterica and Escherichia coli of avifauna origin in Pakistan

Members of Enterobacteriaceae are known to produce extended-spectrum beta-lactamases (ESBL) which hydrolyze the beta-lactam group of antibiotics. The existence of ESBL-producing Salmonella enterica (S. enterica) and Escherichia coli (E. coli) harbored by urban avifauna was investigated in this study. Dropping samples (n= 180) were collected from six different bird species in the district Jhang, Punjab province, Pakistan. Isolation and identification of ESBL isolates were made by using cefotaxime- (4 mg/L) supplemented MacConkey agar and double disc synergy test (DDST). Polymerase chain reaction (PCR) was performed for the detection of four different ESBL genes including blaCTX-M, blaTEM, blaSHV and blaOXA. A total of 42.69% isolates were confirmed as ESBL via DDST including 30.64% S. enterica and 49.54% E. coli. The incidence of ESBL S. enterica and ESBL E. coli was found highest in egret (Ardea alba) and pigeon (Columba livia) as 64.28% and 78.95%, respectively. The blaCTX-M gene was detected in 57.89% and 64.81% of isolates of S. enterica and E. coli, respectively. Among other genes in S. enterica and E. coli, blaTEM (21.05%, 20.4%); blaSHV (15.78%, 9.26%), and blaOXA (5.26%, 5.56%) were detected, respectively. All of the tested isolates were found resistant to at least one of the thirteen antimicrobial agents except meropenem. To the best of our knowledge, this is the first study reporting the incidence and genetic diversity of ESBL bacteria associated with urban avifauna in Pakistan. The urban avifauna can serve as a potential subject of bio-surveillance to monitor the emergence of antimicrobial-resistant bacteria.

Challenges in confirming a varicella outbreak in the two-dose vaccine era

BACKGROUND

A second dose of varicella vaccine was recommended for U.S. children in 2006. We investigated a suspected varicella outbreak in School District X, Texas to determine 2-dose varicella vaccine effectiveness (VE).

METHODS

A varicella case was defined as an illness with maculopapulovesicular rash without other explanation with onset during April 1-June 10, 2011, in a School District X student. We conducted a retrospective cohort in the two schools with the majority of cases. Lesion, saliva, and environmental specimens were collected for varicella-zoster virus (VZV) PCR testing. VE was calculated using historic attack rates among unvaccinated.

RESULTS

In School District X, 82 varicella cases were reported, including 60 from Schools A and B. All cases were mild, with a median of 14 lesions. All 10 clinical specimens and 58 environmental samples tested negative for VZV. Two-dose varicella vaccination coverage was 66.4% in Schools A and B. Varicella VE in affected classrooms was 80.9% (95% CI: 67.2-88.9) among 1-dose vaccinees and 94.7% (95% CI: 89.2-97.4) among 2-dose vaccinees in School A, with a second dose incremental VE of 72.1% (95% CI: 39.0-87.3). Varicella VE among School B students did not differ significantly by dose (80.1% vs. 84.2% among 1-dose and 2-dose vaccinees, respectively).

CONCLUSION

Laboratory testing could not confirm varicella as the etiology of this outbreak; clinical and epidemiologic data suggests varicella as the likely cause. Better diagnostics are needed for diagnosis of varicella in vaccinated individuals so that appropriate outbreak control measures can be implemented.

Ocular findings in sleep apnoea patients using continuous positive airway pressure

PURPOSE

To describe ocular findings in patients with established obstructive sleep apnoea hypopnoea syndrome (OSAHS) using continuous positive airway pressure (CPAP).

METHODS

hundred and fifteen referrals investigated for OSAHS were included. Patients with OSAHS were compared with those with normal sleep study controls. Subgroup analysis for CPAP users and non-users was also carried out.

RESULTS

OSAHS patients (n=89) compared with the controls (n=26) had higher ocular irritation symptoms (P<0.001), abnormal tear break-up time (P<0.05) with increased upper (P<0.001) and lower (P<0.001) lid laxity. Floppy eyelid syndrome (FES) was noted in 31.5% (28/89) OSAHS patients vs 3.8% (1/26) controls (P=0.005). Open angle glaucoma prevalence in OSAHS patients (3/89, 3.4%) was similar to the controls (1/26, 3.8%) (P=0.92). Sixty-seven (75.3%) OSAHS patients were using CPAP (average duration: 19.6+/-15.3 months). All CPAP users maintained a supine sleep posture to prevent mask edge leaks. A fifth of CPAP users (14/67) had experienced earlier episodes of conjunctivitis secondary to leaks. CPAP users had similar upper and lower lid laxity (P=0.746 and 0.633) to non-CPAP users, but a better tear film (P=0.029) and less ocular irritation (P=0.134).

CONCLUSION

OSAHS patients showed increased ocular irritation, abnormal tear film, lid laxity, and FES. The prevalence of glaucoma in our series was similar to normal population data of 2%, P=0.429, and may relate to use of CPAP in majority of the patients. More stable tear film in CPAP users was probably secondary to the supine sleep postures necessarily adopted with CPAP use.